Bone mass declines with age, and the anabolic effects of skeletal loading decrease. While much research has focused on gene transcription, how bone ages and loses its mechanoresponsiveness at the protein level remains unclear.
Researchers Christopher J. Chermside-Scabbo, John T. Shuster, Petra Erdmann-Gilmore, Eric Tycksen, Qiang Zhang, R. Reid Townsend, Matthew J. Silva from Washington University School of Medicine and Washington University in St. Louis, MO, share their findings which underscore the need for complementary protein-level assays in skeletal biology research.
In this study, the tibias of young-adult and old mice were analyzed using proteomics and RNA-seq techniques, while the femurs were examined for age-related changes in bone structure. A total of 1,903 proteins and 16,273 genes were detected through these analyses. Multidimensional scaling demonstrated a clear separation between the young-adult and old samples at both the protein and RNA levels. Furthermore, 93% of the detected proteins were also identifiable by RNA-seq, and the abundance of these shared targets showed a moderately positive correlation. Additionally, differential expression analysis revealed 183 age-related differentially expressed proteins and 2,290 differentially expressed genes between young-adult and old bone samples.
Proteomic and RNA-seq analyses were conducted on paired tibias from young-adult and old mice to study age-related differences and the effects of mechanical loading on bone formation. The results showed distinct differences in protein and gene expression between the two age groups. Many of the significantly upregulated and downregulated proteins and genes in old bone have been associated with bone phenotypes in genome-wide association studies (GWAS). The study also identified age-related differentially expressed proteins and genes involved in bone phenotypes and aging processes. Integrated analysis with GWAS data revealed eight targets that may be relevant to human disease, including Asrgl1 and Timp2. Furthermore, co-expression analysis identified an age-related module indicating baseline differences in TGF-beta and Wnt signaling. Baseline age-related differences in ECM/MMPs and TGF-beta signaling were detected in both the proteome and transcriptome. Following mechanical loading, the proteome showed distinct pathway, protein class, and process enrichments, with temporal differences observed between young-adult and old mice.
Overall, the findings provide valuable insights into the molecular mechanisms underlying age-related changes and the response to mechanical loading in mouse long bones.
DISCUSSION
This study aimed to compare the proteome and transcriptome of tibias from young-adult and old mice under baseline conditions and analyze changes in the bone proteome in response to mechanical loading. The researchers successfully developed a proteomics method to detect protein-level changes in cortical bone and used it to perform proteomic and RNA-seq analyses on tibias from both young-adult and old mice. They observed a moderately positive correlation between the proteome and transcriptome in bone tissue. Age-related differences were detected at both the protein and RNA levels, with altered TGF-beta signaling and changes in extracellular matrix (ECM) and matrix metalloproteinases (MMPs) protein and transcript levels in old bones. The researchers identified Tgfb2 as the most reduced Tgfb transcript in old bone, predominantly expressed by osteocytes. Proteomic analysis of the loading response showed modest changes compared to age-related differences, with fewer protein-level changes in old bones. The findings suggest that proteomics is a valuable tool for studying bone biology and can provide insights into protein-specific changes in aging.
The data obtained from the analysis were subjected to various statistical and data exploration techniques. Differential expression analysis was performed to compare protein abundance between different groups. Total RNA was extracted from the bones using TRIzol, and its integrity and concentration were measured. The bones were also processed for paraffin sectioning and RNA in situ hybridization.
Overall, the study involved the collection and analysis of bone samples from female mice to investigate age-related changes and loading responses in the skeletal system.
Click here to read the full research paper in Aging.
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Aging is indexed by PubMed/Medline (abbreviated as “Aging (Albany NY)”), PubMed Central, Web of Science: Science Citation Index Expanded (abbreviated as “Aging‐US” and listed in the Cell Biology and Geriatrics & Gerontology categories), Scopus (abbreviated as “Aging” and listed in the Cell Biology and Aging categories), Biological Abstracts, BIOSIS Previews, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science).
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“[…] our results suggest that sharing housing with others in early life might influence whole-life attributes, potentially leading to specific life history traits beyond the typical relationship between the growth rate and lifespan.”
A study on African turquoise killifish examined the impact of housing density on juvenile growth. Newly hatched fish were kept in different densities ranging from 1 to 40 fish per tank. It was found that lower housing densities resulted in faster growth, with fish in single housing growing significantly larger than those in group housing. Additionally, single-housed fish reached sexual maturity earlier compared to group-housed fish at higher densities. Comparisons between group-housed and single-housed fish showed that housing conditions in the juvenile stage did not affect the appearance changes during sexual maturation.
As the fish progressed to middle-aged adults, the rate of increase in body length slowed down, while body weight continued to increase. Differences in body weight between group-housed and single-housed fish persisted into old age, suggesting potential differences in body composition. Surprisingly, single-housed fish had a longer mean adult lifespan compared to group-housed fish, contradicting the commonly held belief that faster growth leads to shorter lifespan. Lower housing densities during the juvenile stage were also found to extend adult lifespan, further challenging the inverse correlation between growth rate and lifespan. These findings suggest that lower housing densities promote accelerated growth in the juvenile stage of African turquoise killifish.
The study also found that single-housed fish had a longer adult lifespan compared to group-housed fish. This led to the suspicion that the egg-laying period of single-housed fish might also be longer. To investigate this, the researchers conducted weekly monitoring of the number of eggs laid until the old adult stage. In group-housed fish, the number of eggs laid was high for the first two weeks, followed by a medium level for the subsequent five weeks, and then decreased. In contrast, single-housed fish showed a medium level of egg-laying for the first nine weeks, followed by a decrease. The cumulative number of live embryos was found to be lower in single-housed fish compared to group-housed fish. These findings suggest that while the number of eggs laid is not very high, single-housed fish have a longer egg-laying period than group-housed fish.
To investigate the potential reasons behind the reduction in offspring number and longer egg-laying period in single-housed fish, the researchers conducted RNA sequencing analysis of testes or ovaries at four life stages. These stages included the onset of sexual maturity, young adult, mature adult, and middle-aged adult. Interestingly, the analysis revealed that single-housed fish showed higher similarity to group-housed fish at earlier life stages compared to group-housed fish at the same life stage. For instance, in the testes, single-housed fish at stage II exhibited the highest similarity to group-housed fish at stage I. Similarly, in the ovaries, single-housed fish at stage II and III showed higher similarity to group-housed fish at stage I. These findings suggest that the rate of gonadal transcriptional change with life stage progression is slower in single-housed fish compared to group-housed fish.
The researchers identified differentially expressed genes (DEGs) between stage I and stage IV in group- and single-housed fish. In the testes, ribosome-related genes and cilium-related genes were highly enriched in DEGs with higher expression in stage I compared to stage IV, suggesting a link between life stage progression, testes development, and spermatogenesis. In the ovaries, growth-related genes and translation-related genes were highly enriched in DEGs with higher expression in stage I compared to stage IV, indicating a link between life stage progression, ovarian development, oogenesis, and aging. Comparing group-housed and single-housed fish at different stages, there were differences in the PC1 values, suggesting that single-housed fish exhibited slower progression of gametogenesis and gonadal maturation relative to life stage progression compared to group-housed fish.
To further investigate this, the researchers focused on specific genes related to spermatogenic differentiation, oocyte development, oocyte construction, and female gonad development. The expression of these genes showed slower changes with life stage progression in single-housed fish compared to group-housed fish in both the testes and ovaries. This suggests that single-housed fish may have slower rates of gametogenesis and gonadal maturation, leading to a lower proportion of mature sperm and oocytes in their gonads. Overall, the results indicate that, at the transcriptional level, the progression of gonadal maturation and ovarian aging is slower in single-housed fish compared to group-housed fish. This slower progression may explain the medium fecundity and extended egg-laying period observed in single-housed fish.
The liver was chosen for analysis as it plays a central role in organismal metabolic processes. Gene expression profiles of the livers were compared between group- and single-housed fish at two different ages: 7 weeks post-hatching (wph) and 14 wph. Surprisingly, despite the 2-week age difference, the correlation coefficients showed that group- and single-housed fish at 14 wph were highly similar. The researchers identified 1588 age-related differentially expressed genes (DEGs) between the two age groups. Hierarchical clustering based on the expression changes of these age-related genes demonstrated that the expression profiles of group- and single-housed fish were similar at 14 wph.
IN CONCLUSION
In summary, juvenile single housing in African turquoise killifish promotes faster growth, longer egg-laying periods, and extended lifespans compared to group housing. These findings challenge traditional assumptions about the relationship between growth and lifespan and shed light on the impact of early-life environmental conditions on overall life history.
Overall, the experiments involved maintaining and rearing the fish, measuring their body length and weight, analyzing RNA sequencing data, measuring lifespan, and counting the number of eggs laid. Statistical analysis was conducted to assess significant differences between groups.
Click here to read the full research paper in Aging.
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Aging is indexed by PubMed/Medline (abbreviated as “Aging (Albany NY)”), PubMed Central, Web of Science: Science Citation Index Expanded (abbreviated as “Aging‐US” and listed in the Cell Biology and Geriatrics & Gerontology categories), Scopus (abbreviated as “Aging” and listed in the Cell Biology and Aging categories), Biological Abstracts, BIOSIS Previews, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science).
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Researchers introduce SINGULAR, a cell rejuvenation atlas that provides a unified analysis framework to study the effects of rejuvenation strategies at the single-cell level.
Various strategies, including lifestyle changes, gene therapies, and surgical procedures, have shown promise in improving aging markers and increasing lifespan in model organisms. These interventions often have limitations, however, such as not achieving comprehensive functional improvement across tissues or facing challenges in clinical translation. To address these limitations, the researchers characterized and compared rejuvenation interventions at different biological levels. The paper introduces SINGULAR, a cell rejuvenation atlas that provides a unified analysis framework to study the effects of rejuvenation strategies at the single-cell level. By examining gene regulatory networks, intracellular signaling, cell-cell communication, and cellular processes, the atlas identifies master regulators and common targets across immune cells. SINGULAR has the potential to inform future advancements in human age reversal and aid in the selection of drugs that mimic the effects of rejuvenation interventions.
RESULTS
The authors propose a unified multiscale analysis pipeline for characterizing and comparing the effects of rejuvenation interventions. This process begins by filtering low-quality cells, normalizing expression profiles, and identifying optimal cell clustering. The data is then analyzed at various biological levels, including differential gene expression, transcriptional regulatory networks, signaling cascades, and intercellular communication.
Nine previously published single-cell RNA-seq datasets from different rejuvenation interventions were collected and analyzed, revealing technical variability that highlights the need for a standardized data processing pipeline. The analysis showed heterogeneous gene expression responses across different cell types and organs. Systemic interventions had consistent effects on multiple organs, while metformin had minimal impact. Interestingly, exercise produced the largest transcriptional effects in the liver, artery, and spinal cord, even though it primarily targets muscles.
Transcriptional regulatory networks (TRNs) were reconstructed to explore the regulatory mechanisms behind these gene expression changes. The TRNs, which averaged 72 genes, were highly hierarchical, indicating the presence of ‘master regulators’ that explain significant portions of gene expression changes.
To demonstrate the practical application of SINGULAR, the study investigated the identification of drugs that could target transcription factor (TF) master regulators and key signaling molecules. Drug-target relationships from DrugBank were analyzed to find drugs that could activate master regulators or mimic the effects of rejuvenation interventions. Interestingly, only 17 out of 239 TFs could be activated by drugs, primarily nuclear receptors, with notable exceptions like AP-1 complex proteins and Trp53. Some of these drugs, such as Curcumin and Vitamin D3, have shown rejuvenating effects on lifespan in model organisms. Key signaling molecules were found to be more druggable, with several drugs targeting specific molecules, though none targeted both genes.
The study aimed to identify master regulators and their downstream effects in rejuvenation interventions. By simulating the activation of transcription factors (TFs) within the network, the researchers quantified the number of genes regulated by each TF. They discovered 493 TFs with non-zero activity across various conditions, though most acted as master regulators in only a few cases. The study also highlighted key differences between TFs involved in aging-related activity changes and those regulating rejuvenation. Notably, the AP-1 complex, consisting of Fos and Jun, emerged as a common master regulator across multiple interventions. The researchers also identified TFs linked to aging and validated their potential rejuvenating effects experimentally. They also explored crosstalk between TFs and signaling pathways, finding negative enrichment of aging gene sets in several integrated networks. Overall, the findings offer valuable insights into the regulatory mechanisms and potential rejuvenating effects of master regulators and signaling molecules involved in rejuvenation interventions.
CONCLUSION
In conclusion, this study employed a unified analysis pipeline, SINGULAR, to compare the effects and mediators of various rejuvenation interventions. Key master regulators, including Arntl, AP-1 complex proteins, NFE2L2, and MAF, were identified as playing crucial roles in rejuvenation. The analysis revealed distinct differences between aging-related transcriptional changes and rejuvenation regulators. Immune and skin cell types were highlighted as potential intervention targets, with the possibility of additive or synergistic effects by targeting non-overlapping master regulators. Some limitations were noted, such as biases in cell type comparisons, reliance on ligand-receptor interactions for cell-cell communication analysis, and the risk of false negatives in differential expression testing. Despite these limitations, SINGULAR offers valuable insights into rejuvenation mechanisms and the identification of agents for anti-aging strategies. It provides a robust framework for understanding the mechanisms behind various interventions and offers a wide range of potential target genes for a comprehensive anti-aging approach.
Click here to read the full research paper in Aging.
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Aging is indexed by PubMed/Medline (abbreviated as “Aging (Albany NY)”), PubMed Central, Web of Science: Science Citation Index Expanded (abbreviated as “Aging‐US” and listed in the Cell Biology and Geriatrics & Gerontology categories), Scopus (abbreviated as “Aging” and listed in the Cell Biology and Aging categories), Biological Abstracts, BIOSIS Previews, EMBASE, META (Chan Zuckerberg Initiative) (2018-2022), and Dimensions (Digital Science).
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In this study, researchers reinforce knowledge about an age-related alteration in the synthesis of major proteins linked to the migratory and contractile functions of dermal human fibroblasts.
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Dermal fibroblasts orchestrate the synthesis and degradation of extracellular matrix components, which is crucial for skin homeostasis. Alterations in the expression of components such as collagens and enzymes can lead to reduced mechanical cutaneous tension and impaired skin wound healing during aging.
Researchers Françoise Boismal, Sandy Peltier, Sophie Ly ka so, Guillaume Chevreux, Loïse Blondel, Kévin Serror, Niclas Setterblab, Elina Zuelgaray, David Boccara, Maurice Mimoun, Christelle Guere, Armand Benssussan, Marie Dorr, Gallic Beauchef, Katell Vie, and Laurence Michel from Saint-Louis Hospital, Paris; Paris University, Paris Cité; Jacques-Monod Institute, Paris; and Clarins Laboratories, Pontoise, aimed to better understand the molecular alterations in fibroblasts during aging by comparing secretomic and proteomic signatures of fibroblasts from young (<35years) and aged (>55years) skin donors, in quiescence or TGF-stimulated conditions, using HLPC/MS.
Dermal fibroblasts were obtained from healthy, sun-protected skin of young (<35 years) and aged (>55 years) healthy women undergoing breast reduction surgery. Peptides were loaded using an online preconcentration method and separated by chromatography. RNA extraction, reverse transcription, quantitative PCR, and blot quantification were performed, along with immunostaining on fibroblasts seeded on culture chamber slides.
To identify key molecules involved in the role of human dermal fibroblasts during wound healing and skin aging, a comparative analysis of the secretome and proteome of 12 fibroblast cultures, freshly isolated from young and mature skin, was conducted using HPLC/MS. This analysis was performed in both quiescence and TGF-β1-treated conditions, without senescence-inducing factors, as described in previously reported aging models. Importantly, the analyses were conducted in the absence of serum in the culture medium 24 hours before and during cell stimulation to avoid serum protein contamination in the secretomic and proteomic assays
This study revealed a significant decrease in fibroblast protein secretion with age, while cytoplasmic protein accumulation increased by over 60%. Proteins related to actin and ECM (extracellular matrix) organization were the two main categories altered during aging. An in-depth analysis of actin-related proteins highlighted the involvement of CFL1, CORO1C, the ARP2/3 complex, FLNB, and ACTC1 in cytoskeleton organization and fibroblast migration. These findings offer potential new targets to slow key features of skin aging.
“Our present data reinforce knowledge about an age-related alteration in the synthesis of major proteins linked to the migratory and contractile functions of dermal human fibroblasts.” Read the full research paper, published in Aging.
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Aging is an open-access, traditional, peer-reviewed journal that publishes high-impact papers in all fields of aging research. All papers are available to readers (at no cost and free of subscription barriers) in bi-monthly issues at Aging-US.com.
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In this study, researchers use neuroimaging to see how menopause alters brain structure and connectivity in postmenopausal women.
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Menopause marks the beginning of the next biological chapter in a woman’s life. Characterized by the natural ebb of reproductive hormones (particularly estrogen), menopause ushers in a new season of aging. This hormonal shift not only signifies a transition in fertility but also influences systemic health. The menopause-associated decline in estrogen has been associated with various health issues, including alterations in brain structure and function. However, the mechanics of this phenomenon are still poorly understood. A greater understanding of how menopause alters the brain could aid in the early detection, and possible prevention, of neurodegenerative disease.
“To the best of our knowledge, no comparative neuroimaging study on alterations in the brain volume and functional connectivity, especially focusing on the thalamic subnuclei in premenopausal vs. postmenopausal women has been reported.”
The Study
The decline in estrogen levels during menopause has been linked to an elevated risk of neurodegenerative diseases, notably Alzheimer’s disease (AD). Estrogen plays a pivotal role in modulating neurotransmitter systems, neurotrophins, and brain cytoarchitecture, and there is evidence that these interactions also affect mood, memory, and cognition. The biological mechanisms underlying the increased AD risk in postmenopausal women are not fully understood.
In this study, 21 premenopausal women and 21 postmenopausal women were subjected to magnetic resonance imaging (MRI). The researchers utilized T1-weighted MRI and resting-state functional MRI data to assess differences in brain volume and seed-based functional connectivity. For statistical analysis, they employed multivariate analysis of variance, factoring in age and whole brain volume as covariates, to compare the surface areas and subcortical volumes between the two groups.
Results
Postmenopausal women showed significantly smaller cortical surface, especially in the left medial orbitofrontal cortex (mOFC), right superior temporal cortex (STC), and right lateral orbitofrontal cortex, compared to premenopausal women. These findings suggest that diminished brain volume may be linked to menopause-related symptoms caused by lower sex hormone levels.
In addition to structural changes, the functional connectivity between the brain regions also showed changes. The study found significantly decreased functional connectivity between the left mOFC and the right thalamus in postmenopausal women — reinforcing the hypothesis that the left orbitofrontal-bilateral thalamus connectivity is associated with cognitive impairment. Although postmenopausal women did not show volume atrophy in the right thalamus, the volume of the right pulvinar anterior (PuA), a significant thalamic subnuclei, was significantly decreased. Decreased PuA volume in postmenopausal women is closely related to decreases in female sex hormone levels following menopause.
Expectedly, the study found a significant difference in age and sex hormone levels between premenopausal and postmenopausal women. Postmenopausal women had lower total estrogen and estradiol (E2) levels and higher follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels than premenopausal women. Estrogen levels were positively correlated with the surface area of the left mOFC, right STC, and right lOFC, as well as the volume of the right PuA.
“Concerning the close connection between the estrogen level and STC volume, our findings support a potential role of decreases in sex hormones following menopause due to the correspondent brain structural atrophy. However, further study is needed to elucidate the specific cognitive and emotional implications in connection with these structural changes.”
Conclusions & Future Directions
Postmenopausal women showed significantly lower left mOFC, right lOFC, and right STC surface areas, reduced right PuA volume, and decreased left mOFC-right thalamus functional connectivity compared to premenopausal women. These findings provide novel insight into the structural and functional changes in the brain associated with menopause. However, further research is needed to validate these findings in a larger cohort and to understand the potential cognitive implications of these changes.
“Our findings provide novel insight into the structural and functional changes in the brain associated with menopause.”
Click here to read the full research paper published in Aging.
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Aging is an open-access, traditional, peer-reviewed journal that publishes high-impact papers in all fields of aging research. All papers are available to readers (at no cost and free of subscription barriers) in bi-monthly issues at Aging-US.com.
Click here to subscribe to Aging publication updates.
In Aging’s Volume 14, Issue 15, cover paper, researchers hypothesized that multidimensional well-being may prolong mobility-limitation-free survival and longevity among older adults.
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The Trending With Impact series highlights Aging publications (listed as “Aging (Albany NY)” by Medline/PubMed and “Aging-US” by Web of Science) that attract higher visibility among readers around the world online, in the news, and on social media—beyond normal readership levels. Look for future science news about the latest trending publications here, and at Aging-US.com.
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The word “well-being” is commonly used in workplace environments, therapy sessions, doctor’s offices, books, online, and elsewhere. However, the definition of this word seems to differ across varying contexts, cultures, traditions, values, and even biological sexes. Below are four definitions of well-being:
“noun: [Well-being is] the state of being comfortable, healthy, or happy.” — Oxford English Dictionary
“The meaning of WELL-BEING is the state of being happy, healthy, or prosperous : welfare.” — Merriam-Webster Dictionary
“Well-being, or wellbeing, also known as wellness, prudential value or quality of life, refers to what is intrinsically valuable relative to someone. So the well-being of a person is what is ultimately good for this person, what is in the self-interest of this person.” — Wikipedia
Based on these definitions, one could argue the root meaning of well-being may be distilled down to individual happiness and prosperity that contributes to healthy aging. However, this prosperity and happiness is not anchored to only one domain of well-being. There are three domains of being well, which include behavioral, social and psychological well-being.
Aging & Well-Being
“Successful aging is a multidimensional construct covering behavioral, social, and psychological domains of well-being, all amenable to individual actions and public health interventions [1–4].”
“Despite the rising evidence supporting a multidimensional construct of successful aging, most longitudinal studies still fail to cover well-being indicators belonging to different domains, as shown by the disproportionate amount of literature focusing exclusively on lifestyle factors [45–48].”
Three Domains of Well-Being: 10 Indicators
In their current study, the researchers selected 10 indicators of behavioral, social and psychological well-being: 1) Behavioral: Mediterranean diet, smoking, physical leisure activities, and mental leisure activities; 2) Social: Social leisure activities (i.e., social participation), social connections and socialsupport; 3) Psychological: life satisfaction, negative affect and positive affect.
“Blue zones” are areas around the world with high concentrations of centenarians, or people who live to be over 100 years old. A prevalent diet among people living in blue zones is the Mediterranean diet. The Mediterranean diet consists of fruits, vegetables, whole grains, beans, nuts/seeds, lean poultry, fish, seafood, dairy, eggs, and extra virgin olive oil. This diet has been closely studied as a protective factor of healthy aging.
The psychological well-being indicator listed as “negative affect” refers to the degree to which a person feels guilt, anger and fear, and the following features are considered: distressed, upset, scared, nervous, and afraid. “Positive affect” considers the extent to which a person is active, inspired, determined, alert, and enthusiastic. For additional explanations, the remaining indicators of well-being used in this study are expounded in thorough detail within the research paper itself.
Aging & Mobility
“Mobility decline precedes disability and premature death, and is therefore considered an optimal early indicator of physical function decay among older adults [34].”
The simple ability to exercise, complete day-to-day chores and maintain personal hygiene all rely on a minimum range of physical mobility. A sedentary lifestyle is a well-recognized risk factor for chronic diseases, such as obesity, type 2 diabetes, cardiovascular disease, and some forms of cancer. Furthermore, mobility limitations are associated with social isolation, depression and cognitive decline. The researchers in this study aimed to identify well-being profiles and their association with mobility-limitation-free survival.
“The specific aims of this study were: 1) to identify distinct well-being profiles among men and women separately, by using latent class analysis; 2) to determine which of these profiles are associated with the greatest benefit in terms of mobility-limitation-free survival; and 3) to quantify these potential benefits in absolute terms by calculating differences in median age at onset of mobility limitation or death across profiles.”
The Study
The study population consisted of 1488 functionally healthy individuals (after all exclusion criteria were applied to the ongoing Swedish National Study on Aging and Care in Kungsholmen (SNAC-K) population-based study). In addition to collecting self-reported data on the 10 indicators of behavioral, social and psychological well-being listed above, the researchers included data on the participants’ covariates. Covariates included age, education, number of chronic diseases, mini-Mental State Examination score (MMSE), and NEO Five-Factor Inventory (NEO-FFI) questionnaire. At the beginning of the study (baseline), the average age in the cohort was 69 years old (with a standard deviation of +/- 8.3 years). Ninety-one percent of participants had at least a high-school-level of education. Females (59%) composed the majority of the cohort.
“In this study, we used latent class analysis to detect data-driven subgroups of people with similar well-being profiles according to behavioral (diet, smoking, and physical and mental leisure activities), social (social participation, connections, and support) and psychological (life satisfaction, positive and negative affect) well-being indicators, as defined by the Centers for Disease Control and Prevention (CDC) [25].”
Since men and women tend to behave differently when it comes to multiple factors of well-being, the researchers stratified their analyses by sex. They scheduled regular followed-ups with these participants over the course of 15 years. Well-being profiles were derived from the 10 well-being indicators using latent class analysis. Endpoints were defined as mobility-limitation-free survival, limited mobility or death. Limited mobility was defined as having a walking speed below 0.8 meters per second.
“A composite endpoint, considered to be an indicator of mobility-limitation-free survival, was operationalized by taking into account the time from study entry until the development of mobility limitation (i.e., walking speed <0.8m/s) or death, whichever occurred first.”
Results
At baseline, the researchers identified three well-being profiles among both men and women that followed a clear gradient in all behavioral, social and psychological indicators throughout the study. Participants categorized in the best well-being profile had high adherence to the Mediterranean diet, the lowest proportion of current smokers, high engagement with leisure activities, and the highest levels of social and psychological well-being. Those in the intermediate well-being profile had low/moderate adherence to the Mediterranean diet, a higher proportion of former/never smokers, and moderate levels of social and psychological well-being. (Men in the intermediate well-being profile had a low/moderate engagement in leisure activities, while women had moderate/high engagement levels.) Participants in the worst well-being profile had low adherence to the Mediterranean diet, a higher proportion of former/never smokers, the lowest levels of leisure activity engagement, and the lowest levels of social and psychological well-being.
To examine the association between these well-being profiles and the incidence of mobility limitation or death, the researchers used Cox and Laplace regression models and applied sensitivity analyses to the data.
“In agreement with the Cox regressions, results from Laplace regressions showed that men in the intermediate and best profiles survived 1 and 3 years longer without mobility limitations, respectively, compared to those in the worst profile after adjustment for potential confounders (Figure 2). Women in the intermediate and best profiles lived 2 and 3 years longer without mobility limitations, respectively, compared to those in the worst profile.”
Conclusion
The well-being profiles of older adults are associated with their risk of developing mobility limitations and death. Those in the best well-being profile had the lowest risk, while those in the worst well-being profile had the highest risk. These findings suggest that interventions to improve multi-domain well-being in older adults may improve longevity and help reduce the incidence of mobility limitations in old age. Although this study has many strengths, the researchers were forthcoming about its limitations. Future studies are recommended to confirm these findings.
“While theoretical insights into different models of successful aging are on the rise, empirical evidence from population-based longitudinal data on the complex interplay among the distinct well-being domains and their association with person-centered outcomes, such as mobility-limitation-free survival, is currently lacking. This study addresses such an important gap and provides further evidence to better understand and promote functional independence in community-dwelling older adults through primary prevention multi-domain interventions.”
Click here to read the full research paper published by Aging.
Agingis an open-access journal that publishes research papers bi-monthly in all fields of aging research. These papers are available at no cost to readers on Aging-us.com. Open-access journals have the power to benefit humanity from the inside out by rapidly disseminating information that may be freely shared with researchers, colleagues, family, and friends around the world.
In the cover paperpublished inAging-US Volume 14, Issue 10, researchers investigated a potential therapeutic intervention to reduce chronic inflammation in age-related macular degeneration (AMD).
The Trending With Impact series highlights Aging (Aging-US) publications that attract higher visibility among readers around the world online, in the news, and on social media—beyond normal readership levels. Look for future science news about the latest trending publications here, and at Aging-US.com.
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One of the leading causes of vision loss among aging populations in the United States, and worldwide, is age-related macular degeneration (AMD). The progression of this disease is known to be driven by inflammatory processes. However, the exact inflammation-associated proteins and the mechanisms that drive them have not yet been fully elucidated.
“Inflammation plays a crucial role in the etiology and pathogenesis of AMD (Age-related Macular Degeneration).”
“Our discovery is novel and may contribute to the development of therapeutics/ tools for reducing inflammation to alleviate AMD disease pathology.”
The Study
Humanin G (HNG) is a naturally produced peptide that may play a pivotal role in tissue homeostasis and normal functioning throughout the body—including the eyes. Previous studies have shown that high-intensity exercise and resistance training positively correlate with protein levels of Humanin G in human plasma and skeletal muscle. Studies have also shown that Humanin G protein levels negatively correlate with aging. In this study, researchers investigated the impact of exogenous Humanin G on markers of inflammation in AMD cells.
“Moreover, treatment with exogenous Humanin G is known to reduce the expression of markers associated with aging-related disorders [32]. Therefore, we tested the effects of Humanin G on inflammatory markers in this study.”
First, the researchers measured levels of inflammation-associated proteins (including cell adhesion molecules, cytokines and chemokines) among samples of AMD plasma and normal (control) plasma. AMD plasma showed higher protein levels of inflammation markers compared to control plasma samples. Next, the researchers used the ELISA assay to measure Humanin G protein levels in the plasma of both AMD patients and normal subjects. They found that, in AMD patients, protein plasma levels of Humanin G were significantly lower compared to normal subjects.
“In the current study, we found that the plasma levels of endogenous Humanin protein were significantly lower by 36.58 % in AMD patients compared to that in age-matched normal subjects.”
Exogenous Humanin G was then added to AMD and normal (control) cybrids derived from clinically characterized AMD patients and normal (control) subjects. Cell lysates were extracted from untreated and Humanin G-treated AMD and normal cybrids. Levels of inflammatory proteins were measured using the Luminex XMAP multiplex assay. The researchers observed that protein levels of inflammation markers previously elevated in AMD cells were reduced after Humanin G treatment.
“To our knowledge, this is the first report that confirms the protective role of Humanin G against inflammation in AMD RPE transmitochondrial cybrid cells and it is significant because reducing ocular inflammation could alleviate its damaging effects observed in the RPE cells that eventually lead to retinal degeneration in AMD pathogenesis.”
Conclusion
“In conclusion, we present novel findings that: A) show reduced Humanin protein levels in AMD plasma vs. normal plasma; B) suggest the role of inflammatory markers in AMD pathogenesis, and C) highlight the positive effects of Humanin G in reducing inflammation in AMD.”
Results in this study are significant because treatment with exogenous Humanin G may be able to revert the abnormal levels of inflammatory proteins that are found in AMD patients back to (or near) normal ranges. These findings may lead to novel therapeutics that can improve AMD disease trajectory.
“Further studies are required to gain an in-depth understanding of the mechanisms underlying Humanin G-mediated suppression of inflammation in AMD and to establish Humanin G’s therapeutic potential as an inhibitor of AMD-associated inflammation. Furthermore, in addition to administration of Humanin G, knockdown or knock-out of the studied inflammatory markers using siRNA or CRISPR editing, may present a new line of treatment for AMD.”
Click here to read the full research paper published by Aging (Aging-US).
Aging (Aging-US) is an open-access journal that publishes research papers bi-monthly in all fields of aging research. These papers are available at no cost to readers on Aging-us.com. Open-access journals have the power to benefit humanity from the inside out by rapidly disseminating information that may be freely shared with researchers, colleagues, family, and friends around the world.
Patients over the age of 50 years old who have been diagnosed with pancreatic cancer have a poorer rate of survival compared to younger patients. This means that pancreatic cancer is a disease associated with aging. The most common type of pancreatic cancer is pancreatic ductal adenocarcinoma (PDAC) and it is frequently diagnosed in its later stages. PDAC is often refractive to chemotherapies and develops resistance to inhibitors and other drugs. Therefore, there is a critical need for researchers to discover novel strategies to overcome drug resistance in PDAC cells.
One potential strategy is to focus on a key gene known for its involvement in many cell processes, including drug resistance and metabolism: TP53. The TP53 gene is often mutated or deleted in cancer cells, which can lead to drug resistance and cancer metastasis. In PDACS, this tumor suppressor gene has been shown to be mutated in 50–75% of patients.
“Many genes have been implicated in PDAC including KRAS, TP53, CDKN2A, SMAD4 and PDGFβR [3, 8, 9, 18–22].”
In these in vitro studies, the researchers cultured two different PDAC cell lines. One cell line had a gain of function (GOF) TP53 mutation (MIA-PaCa-2) and the other had a loss of TP53 (PANC-28). Both PDAC cell lines also have activating mutations in the KRAS gene. Next, the team introduced either wild-type TP53 (WT-TP53) or a control vector into both PDAC cell lines. Effects from this experiment were analyzed using 26 clinically approved agents.
The chemotherapeutic drugs included: Docetaxel, 5-fluorouracil (5-FU), gemcitabine, Aclacinomycin, Doxorubicin, and Cisplatin. The signal transduction inhibitors included: ARS-1620, PD0325901, LY294002, Pifithrin-μ, 6-bromoindirubin-30-oxime (BIO), SB415286, CHIR99021, Rapamycin, AG1498, Gilteritinib, Sorafenib, OTX008, Tiplaxtinin, Verapamil, and Vismodegib. The natural products included: Cyclopamine, Parthenolide2, Isoliquiritin2, Genistein2, and Daidzein2. The researchers also illustrated the effects of WT-TP53 and mutant TP53 on PDAC cell metabolism with metformin and rapamycin.
“An overview of the effects of WT and mutant TP53 on metabolic properties, together with the effects of metformin and rapamycin, and drugs used to inhibit pancreatic cancer growth, is presented in Figure 16.”
Figure 16.Influences of mutant and WT-TP53 on mitochondrial activity and glucose metabolism and effects of rapamycin and metformin. The effects of WT and mutant TP53 on key enzymes important in glycolysis and how they can influence metabolism and PDAC tumor growth. In our studies, we have examined the effect of GOF mutant TP53 and in some cases WT TP53. In addition, sites of interaction of the type 2 diabetes drug metformin and the immunosuppressive drug rapamycin and their effects on AMPK and mTORC1 are indicated. TP53 can induce mitochondrial apoptosis pathway by regulating the expression of PUMA and other proteins.
The Results
The researchers found that, in the presence of chemotherapeutic drugs, PDAC clonogenicity was decreased by the restoration of WT-TP53. Overall, the restoration of WT-TP53 in PDAC cells increased sensitivity/decreased resistance to various chemotherapeutic drugs, inhibitors and natural products. WT-TP53 also influenced PDAC cell metabolic properties, including their metabolism. The authors also noted that the activity of mTORC1 (target of rapamycin), which is important in cellular growth and metabolism, can be affected by mutant TP53. They found that GOF mutated TP53 may render PDAC cells more resistant to rapamycin.
“Rapamycin and metformin can interfere with some of the important pathways in the mitochondria, some of which are regulated by TP53 [96–98].”
Conclusion
Overall, these results suggest that WT-TP53 can play a key role in PDAC cell sensitivity to multiple drugs used to treat pancreatic cancer. Further studies are needed to better understand the mechanisms underlying the effects of TP53 on drug resistance and metabolism in PDAC cells, as well as its clinical implications.
“Regardless of which of the above processes contributes more to the reduction of mitochondrial metabolism in comparison with the same cells that only express GOF TP53, together the observed changes suggest restoration of WT-TP3 activity confers increased sensitization to various drugs and therapeutic molecules, natural products as well as nutraceuticals.”
Click here to read the full research paper published by Aging (Aging-US).
Aging (Aging-US) is an open-access journal that publishes research papers bi-monthly in all fields of aging research. These papers are available at no cost to readers on Aging-us.com. Open-access journals have the power to benefit humanity from the inside out by rapidly disseminating information that may be freely shared with researchers, colleagues, family, and friends around the world.
Researchers used PandaOmics software to identify potential drug targets that could treat both aging and age-related diseases.
The Trending With Impact series highlights Aging (Aging-US) publications that attract higher visibility among readers around the world online, in the news, and on social media—beyond normal readership levels. Look for future science news about the latest trending publications here, and at Aging-US.com.
The PandaOmics platform is a software based on an enormous database of research that is constantly being updated and refined. The database consists of over 1,500 diseases and 10,000 disease subtypes, approximately 1.9 trillion data points derived from over 10 million samples with microarrays, RNA sequencing, proteomes, methylomes, and other data types, 1.3 million drug compounds and biologics, and information embedded from over 40 million text-based sources and documents. This evolving omics database is then used to inform an intricate AI algorithm designed to identify patterns within the data.
The Hallmarks of Aging
While the underlying molecular mechanisms of aging are still technically in debate, researchers have basically agreed upon a consistent series of biochemical changes that have been identified in the aging process, known as the hallmarks of aging. There are nine classic hallmarks of aging, as well as three newer additions, which include: 1) altered intercellular communications, 2) cellular senescence, 3) deregulated nutrient signaling, 4) epigenetic shift, 5) genomic instability, 6) impaired proteostasis, 7) mitochondrial dysfunction, 8) stem cell exhaustion, 9) telomere attrition, 10) inflammation, 11) extracellular matrix stiffness, and 12) retrotransposons.
Researchers have observed that substantial overlap exists between genes involved in the hallmarks of aging and in age-associated diseases (AADs). The goal of this study was to use the PandaOmics platform and the hallmarks of aging to identify dual-purpose drug targets that can be used to treat both aging and AADs.
“Hence, identifying potential targets that are implicated in multiple age-associated diseases, and also play a role in the basic biology of aging, may have substantial benefits.”
The Study
In this study, the researchers used the PandaOmics platform to generate a list of promising new or traditional aging-associated targets that may be used for drug discovery and repurposing. The team started by investigating genes that are dysregulated in multiple aging-associated diseases, as well as in aging itself. The researchers decided only to analyze 33 diseases. This decision was based on whether or not age is a strong risk factor for the disease’s onset, if there are strong confounding factors and on the availability of public datasets. Cancers and cardiovascular diseases were excluded from this list of selected diseases (this list can be found in the study).
The selected diseases were separated into AADs (n=14) and non-age-associated diseases (NAADs) (n=19). The team then programmed the PandaOmics platform to identify aging-associated patterns by prioritizing the top dysregulated genes in these diseases based on their involvement in the hallmarks of aging. The researchers compared the top-AAD and -NAAD genes and identified 145 overlapping common targets.
Results
“In this study, we used a variety of target identification and prioritization techniques offered by the AI-powered PandaOmics platform, to propose a list of promising novel aging-associated targets that may be used for drug discovery. We also propose a list of more classical targets that may be used for drug repurposing within each hallmark of aging.”
They found that most aging-associated targets were not specific to a single hallmark but were instead involved in multiple hallmarks. The team also found that most of the top targets played a role in the 10) inflammation and 11) extracellular matrix stiffness hallmarks of aging. Four targets were connected to all 12 hallmarks; these targets were AKT1, MTOR, SIRT1, and IGF1. Primary conclusions drawn from the study were that the hallmarks of aging are implicated in multiple AADs and NAADs, and that these hallmarks can be used to identify aging-associated targets for drug discovery and repurposing.
Figure 3.Targets associated with hallmarks of aging.
Conclusion
The researchers were forthcoming about limitations in this study. Nevertheless, this exciting research provides valuable insight into the use of AI-powered discovery engines to uncover novel aging-associated targets for drug discovery. The PandaOmics platform is a valuable resource for aging researchers and offers the potential to identify new or traditional targets for the treatment of aging and age-related diseases.
“In conclusion, we successfully established an approach to identify potential dual-purpose targets for aging and AADs, enabling biologists and clinicians to further investigate their therapeutic potential in a cost-saving and time-efficient manner for drug discovery. These promising results underscore the ability of PandaOmics to identify novel targets not only for specific disorders, but across multiple types of diseases.”
Click here to read the full cover paper published in Aging (Aging-US).
Aging (Aging-US) is an open-access journal that publishes research papers bi-monthly in all fields of aging research. These papers are available at no cost to readers on Aging-us.com. Open-access journals have the power to benefit humanity from the inside out by rapidly disseminating information that may be freely shared with researchers, colleagues, family, and friends around the world.
Researchers investigated the functional significance of Muc4 in intestinal homeostasis and colorectal cancer progression.
Figure 3. Absence of Muc4 alters other mucins expression.
The Trending With Impact series highlights Aging (Aging-US) publications that attract higher visibility among readers around the world online, in the news, and on social media—beyond normal readership levels. Look for future science news about the latest trending publications here, and at Aging-US.com.
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With age, humans undergo bodily changes which include a decline in organ and tissue function. The average age men and women are diagnosed with colorectal cancer (CRC) is 68 and 72 years old, respectively. Healthy intestinal epithelial cells are usually lined with a sufficient layer of mucus; important components in this mucus layer, called mucins, help to maintain physiological homeostasis. While transmembrane mucin 4 (Muc4) has been found to be overexpressed in pancreatic, ovarian and breast cancers, Muc4 expression is decreased in patients with CRC. The functional role and implications of Muc4 in CRC’s intestinal pathology have not yet been adequately investigated.
“Therefore, to understand the functional significance of MUC4 in intestinal homeostasis and CRC progression, we developed a GEM model by crossing mice carrying a conditional mutation of Apc [adenomatous polyposis coli] gene with colon-specific caudal type homeobox transcription factor 2 (Cdx2)-Cre fused with estrogen receptor.”
The Study
The researchers first conducted an analysis of CRC patients using The Cancer Genome Atlas. They found that CRC patients had decreased Muc4 levels compared to normal patients and that lower Muc4 expression is associated with a worse prognosis in CRC patients. In CRC, the most frequent mutations were found to occur in the Apc gene. Therefore, the researchers tested control mice and two mouse models in this study. The AMC GEM model had an Apc mutation, and Muc4 was knocked out. The AC GEM model was AMC’s contemporary littermate control and had only the Apc mutation—Muc4 was not knocked out. Tamoxifen was then intraperitoneally administered to exert conditional control of gene expression in the mice.
Next, the team conducted mucin staining to characterize goblet cell function. Goblet cells protect the intestine by secreting mucins. In addition to Apc mutations, many CRC patients have Kras gene mutations. Therefore, the researchers also crossed the AMC mouse model with a mutated Kras mouse model. Finally, the researchers examined two human CRC cell lines in vitro. They performed a knockdown of Muc4 and conducted a cellular fractionation study of the cell lines.
“Knockdown (KD) of MUC4 increased the expression of β-catenin, cyclin-D1, and CD44 at the transcript level in LS-180 and HCT-8 cells (Supplementary Figure 3C).”
The Results
The researchers found that Muc4 deletion in the AMC mice resulted in more colorectal tumors with high-grade dysplasia compared to AC and normal mice. Immunohistochemistry staining revealed that AMC and AC mice did not produce any visible goblet cells.
“We observed that in both AMC and AC mice, there was a complete absence or loss of staining in the goblet cells of colon adenoma (Figure 2E), suggesting that disruption of goblet cell function alters the mucin production.”
Muc4 knock-out in AMC mice was associated with an upregulation of Muc13 and a significant loss of Muc2 and Fam3D in CRC tissues. The researchers observed that Muc4 deletion resulted in defective mucus barrier function, reduced intestinal homeostasis and up-regulated β-catenin signaling. In the Kras/AMC mice, they found that the addition of the Kras mutation further aggravated tumors and reduced survival.
Conclusion
The research team found that, in the AMC GEM model (lacking mucin expression), there was an increase in inflammation, DNA damage, tumor burden, and CRC cell proliferation. The study’s findings provide evidence that Muc4 expression is essential for the proper maintenance of the mucus layer and intestinal homeostasis. Furthermore, this research suggests that reduced expression of Muc4 may be associated with aging and a predisposition to colorectal cancer.
“In conclusion, our study suggests that Muc4 has a protective role in CRC progression in an Apc mutant GEM mice model. Muc4 maintains the intestinal homeostasis by upregulation of Muc2 and Fam3D (guardians of the gut) and downregulation of cancer-promoting mucin (Muc13). Additionally, presence of Muc4 prevents the invasion of microbiota and reduction of proinflammatory cytokines and decrease in epithelial cell proliferation by inhibiting β-catenin, c-Myc and CD44 expression. Additional studies are needed to understand the role of Muc4 in conditional KO mouse models and various sub-types of CRC.”
Click here to read the full priority research paper published by Aging (Aging-US).
Aging (Aging-US) is an open-access journal that publishes research papers bi-monthly in all fields of aging research. These papers are available to read at no cost to readers on Aging-us.com. Open-access journals offer information that has the potential to benefit our societies from the inside out and may be shared with friends, neighbors, colleagues, and other researchers, far and wide.
