Chloride intracellular channels in oncology as potential novel biomarkers and personalized therapy targets: a systematic review.

Background: The chloride intracellular channels (CLICs) family includes six ion channels (CLIC1-CLIC6) expressed on the cellular level and secreted into interstitial fluid and blood. They are involved in the physiological functioning of multiple systems as well as the pathogenetic processes of cancer. CLICs play essential roles in the tumor microenvironment. The current systematic review aimed at identifying and summarizing the research of CLICs in oncology on clinical material to assess CLICs' potential as novel biomarkers and personalized therapy targets. Materials and methods: The authors systematically searched the PubMed database for original articles concerning CLIC research on clinical material of all types of cancer - fluids and tissues. Results: Fifty-three articles investigating in summary 3944 clinical samples were qualified for the current review. Studied material included 3438 tumor samples (87%), 437 blood samples (11%), and 69 interstitial fluid samples (2%). Studies investigated 21 cancer types, mostly hepatocellular carcinoma, colorectal, ovarian, and gastric cancer. Importantly, CLIC1, CLIC2, CLIC3, CLIC4, and CLIC5 were differently expressed in cancerous tissues and patients' blood compared to healthy controls. Moreover, CLICs were found to be involved in several cancer-associated signaling pathways, such as PI3K/AKT, MAPK/ERK, and MAPK/p38. Conclusion: CLIC family members may be candidates for potential novel cancer biomarkers due to the contrast in their expression between cancerous and healthy tissues and secretion to the interstitial fluid and blood. CLICs are investigated as potential therapeutic targets because of their involvement in cancer pathogenesis and tumor microenvironment.

MASLD does not affect fertility and senolytics fail to prevent MASLD progression in male mice.

Senescent cells have been linked to the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD). However, the effectiveness of senolytic drugs in reducing liver damage in mice with MASLD is not clear. Additionally, MASLD has been reported to adversely affect male reproductive function. Therefore, this study aimed to evaluate the protective effect of senolytic drugs on liver damage and fertility in male mice with MASLD. Three-month-old male mice were fed a standard diet (SD) or a choline-deficient western diet (WD) until 9 months of age. At 6 months of age mice were randomized within dietary treatment groups into senolytic (dasatinib + quercetin [D + Q]; fisetin [FIS]) or vehicle control treatment groups. We found that mice fed choline-deficient WD had liver damage characteristic of MASLD, with increased liver size, triglycerides accumulation, fibrosis, along increased liver cellular senescence and liver and systemic inflammation. Senolytics were not able to reduce liver damage, senescence and systemic inflammation, suggesting limited efficacy in controlling WD-induced liver damage. Sperm quality and fertility remained unchanged in mice developing MASLD or receiving senolytics. Our data suggest that liver damage and senescence in mice developing MASLD is not reversible by the use of senolytics. Additionally, neither MASLD nor senolytics affected fertility in male mice.

The role of cellular senescence in ovarian aging.

This review explores the relationship between ovarian aging and senescent cell accumulation, as well as the efficacy of senolytics to improve reproductive longevity. Reproductive longevity is determined by the age-associated decline in ovarian reserve, resulting in reduced fertility and eventually menopause. Cellular senescence is a state of permanent cell cycle arrest and resistance to apoptosis. Senescent cells accumulate in several tissues with advancing age, thereby promoting chronic inflammation and age-related diseases. Ovaries also appear to accumulate senescent cells with age, which might contribute to aging of the reproductive system and whole organism through SASP production. Importantly, senolytic drugs can eliminate senescent cells and may present a potential intervention to mitigate ovarian aging. Herein, we review the current literature related to the efficacy of senolytic drugs for extending the reproductive window in mice.

Impact of repeated ovarian hyperstimulation on the reproductive function.

One of six couples (17.5 % of the adult population) worldwide is affected by infertility during their lifetime. This number represents a substantial increase in the prevalence of this gynecological condition over the last decade. Ovulatory dysfunction and anovulation are the main causes of female infertility. Timed intercourse, intrauterine insemination, and assisted reproductive technology (ART), such as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), are the most common interventions for infertile couples. Ovulation induction protocols for IVF/ICSI routinely use supraphysiological doses of gonadotropins to stimulate many preovulatory follicles. Animal and human studies suggested that ovarian hyperstimulation, alone or repeatedly, for ART cycles can induce changes in the immune response and increase the oxidative stress (OS) in the ovarian microenvironment. The consequences of repeated ovarian hyperstimulation on the human ovary remain poorly understood, particularly in relation to the effects of ovarian stimulation on the immune system and the potential for ovarian stimulation to cause OS. Animal studies have observed that repeated cycles of ovarian hyperstimulation can accelerate ovarian aging. Changes in ovarian hormone levels, accelerated loss of ovarian reserve, disorders in ovarian ultrastructure, ovarian senescence, and decreased reproductive performance represent possible long-term effects of repeated ovarian hyperstimulation. The short and long-term impact of the combination of antioxidant agents in ovarian hyperstimulation protocols in women undergoing ART must urgently be better understood. The recent increase in the number of ART and fertility preservation cycles may accelerate ovarian aging in these women, promoting consequences beyond the reproductive function and including health deterioration.

Calorie restriction and life-extending mutation downregulate miR-34a to facilitate lipid metabolism in the liver.

Ames dwarf mice (df/df) display delayed aging relative to their normal (N) siblings, living approximately 40-60 % longer. As such, investigating the mechanisms that enable these organisms to have extended lifespan is useful for the development of interventions to slow aging and deter age-related disease. Nonalcoholic fatty liver disease (NAFLD) is a condition that is characterized by the accumulation of excess adipose tissue in the liver. Previous studies highlight the potential of calorie restriction (CR) in promoting longevity, but little is known about its effects on the biomolecular processes that govern NAFLD. In this study, we examined the role of 6-month CR on genes regulating lipid metabolism in the livers of long-living df/df mice and their N littermates. Importantly, our findings showed significant downregulation of miR-34a-5p in N-CR mice and df/df mice regardless of dietary regimen. Alongside, our RT-PCR results indicated that downregulation of miR-34a-5p is correlated with the expression of metabolism-associated mRNAs involved in modulating the processes of de novo lipogenesis (DNL), fatty acid oxidation (FAO), very-low density lipoprotein transport (VLDL-T), and reverse cholesterol transport (RCT). To further verify the role of miR-34a-5p in regulating metabolic processes, we transfected the human liver cancer (HepG2) cell line with miR-34a mimic, and studied its effect on direct targets Sirt1, Ampk, and Ppara as well as downstream lipid transport regulating genes. Our findings suggest that CR and df/df life extending mutation are robust drivers of the miR-34a-5p signaling pathway and prevent the pathogenesis of age-related diseases by improving overall lipid homeostasis.

Circulating microRNA profile of long-lived Okinawans identifies novel potential targets for optimizing lifespan and health span.

Nonagenarians and centenarians serve as successful examples of aging and extended longevity, showcasing robust regulation of biological mechanisms and homeostasis. Given that human longevity is a complex field of study that navigates molecular and biological mechanisms influencing aging, we hypothesized that microRNAs, a class of small noncoding RNAs implicated in regulating gene expression at the post-transcriptional level, are differentially regulated in the circulatory system of young, middle-aged, and nonagenarian individuals. We sequenced circulating microRNAs in Okinawan males and females <40, 50-80, and >90 years of age accounting for FOXO3 genetic variations of single nucleotide polymorphism (SNP) rs2802292 (TT - common vs. GT - longevity) and validated the findings through RT-qPCR. We report five microRNAs exclusively upregulated in both male and female nonagenarians with the longevity genotype, play predictive functional roles in TGF-ß, FoxO, AMPK, Pi3K-Akt, and MAPK signaling pathways. Our findings suggest that these microRNAs upregulated in nonagenarians may provide novel insight into enhanced lifespan and health span. This discovery warrants further exploration into their roles in human aging and longevity.

Early life interventions metformin and trodusquemine metabolically reprogram the developing mouse liver through transcriptomic alterations.

Recent studies have demonstrated the remarkable potential of early life intervention strategies at influencing the course of postnatal development, thereby offering exciting possibilities for enhancing longevity and improving overall health. Metformin (MF), an FDA-approved medication for type II diabetes mellitus, has recently gained attention for its promising anti-aging properties, acting as a calorie restriction mimetic, and delaying precocious puberty. Additionally, trodusquemine (MSI-1436), an investigational drug, has been shown to combat obesity and metabolic disorders by inhibiting the enzyme protein tyrosine phosphatase 1b (Ptp1b), consequently reducing hepatic lipogenesis and counteracting insulin and leptin resistance. In this study, we aimed to further explore the effects of these compounds on young, developing mice to uncover biomolecular signatures that are central to liver metabolic processes. We found that MSI-1436 more potently alters mRNA and miRNA expression in the liver compared with MF, with bioinformatic analysis suggesting that cohorts of differentially expressed miRNAs inhibit the action of phosphoinositide 3-kinase (Pi3k), protein kinase B (Akt), and mammalian target of rapamycin (Mtor) to regulate the downstream processes of de novo lipogenesis, fatty acid oxidation, very-low-density lipoprotein transport, and cholesterol biosynthesis and efflux. In summary, our study demonstrates that administering these compounds during the postnatal window metabolically reprograms the liver through induction of potent epigenetic changes in the transcriptome, potentially forestalling the onset of age-related diseases and enhancing longevity. Future studies are necessary to determine the impacts on lifespan and overall quality of life.

Skin assessment in congenital untreated isolated GH deficiency.

PURPOSE: The separation between the inside and outside through the skin was fundamental for the evolution of prevertebrates, which grow through extrapituitary circuits, to vertebrates, which grow through the somatotrophic axis, namely pituitary growth hormone (GH). and circulating IGF1.Individuals with untreated isolated growth hormone (GH) deficiency (IGHD) due to a mutation in the GH-releasing hormone receptor (GHRH) gene, residing in Itabaianinha, Brazil, are vulnerable to skin cancer and have reduced sweating. However other aspects of their skin physiology are still unknown. Our objectives were to evaluate the number of skin cancers, skin aging, and functional aspects of the skin in this IGHD cohort. METHODS: Twenty-six IGHD individuals and 26 controls matched by age, sex, ethnicity, and occupation were submitted to a biochemical, dermatological and a functional skin assessment by the Multi Probe Adapter Cutometer® MPA 580. RESULTS: There was no difference in the number of skin cancers and in the degrees of photodamage between the groups. The melanin content in the forearm was similar between the groups but was lower in the buttocks (p = 0.005), as well as skin resistance (p < 0.0001) and elasticity (p = 0.003), lower in the IGHD. There was no difference in hydration and sebum content between the two groups. CONCLUSION: IGHD is apparently associated with a neutral profile in terms of skin cancer and photodamage, with similar melanin on the forearm and lower buttocks, lower skin resistance and elasticity, with hydration and sebum similar to controls.

Senolytics prevent age-associated changes in female mice brain.

PURPOSE: Considering that the combination of dasatinib and quercetin (D + Q) demonstrated a neuroprotective action, as well as that females experience a decline in hormonal levels during aging and this is linked to increased susceptibility to Alzheimer's disease, in this study we evaluated the effect of D + Q on inflammatory and oxidative stress markers and on acetylcholinesterase and Na+, K+-ATPase activities in brain of female mice. METHODS: Female C57BL/6 mice were divided in Control and D (5 mg/kg) + Q (50 mg/kg) treated. Treatment was administered via gavage for three consecutive days every two weeks starting at 30 days of age. The animals were euthanized at 6 months of age and at 14 months of age. RESULTS: Results indicate an increase in reactive species (RS), thiol content and lipid peroxidation followed by a reduction in nitrite levels and superoxide dismutase, catalase and glutathione S-transferase activity in the brain of control animals with age. D+Q protected against age-associated increase in RS and catalase activity reduction. Acetylcholinesterase activity was increased, while Na+, K+-ATPase activity was reduced at 14 months of age and D+Q prevented this reduction. CONCLUSION: These data demonstrate that D+Q can protect against age-associated neurochemical alterations in the female brain.

Senolytic treatment fails to improve ovarian reserve or fertility in female mice.

Senescent cell number increases with age in different tissues, leading to greater senescent cell load, proinflammatory stress, and tissue dysfunction. In the current study, we tested the efficacy of senolytic drugs to reduce ovarian senescence and improve fertility in reproductive age female mice. In the first experiment, 1-month-old C57BL/6 female mice were treated every other week with D + Q (n = 24) or placebo (n = 24). At 3 and 6 months of age, female mice were mated with untreated males to evaluate pregnancy rate and litter size. In the second experiment, 6-month-old C57BL/6 female mice were treated monthly with D + Q (n = 30), fisetin (n = 30), or placebo (n = 30). Females were treated once a month until 11 months of age, then they were mated with untreated males for 30 days to evaluate pregnancy rate and litter size. In the first experiment, D + Q treatment did not affect pregnancy rate (P = 0.68), litter size (P = 0.58), or ovarian reserve (P > 0.05). Lipofuscin staining was lower in females treated with D + Q (P = 0.04), but expression of senescence genes in ovaries was similar. In the second experiment, D + Q or fisetin treatment also did not affect pregnancy rate (P = 0.37), litter size (P = 0.20), or ovarian reserve (P > 0.05). Lipofuscin staining (P = 0.008) and macrophage infiltration (P = 0.002) was lower in fisetin treated females. Overall, treatment with D + Q or fisetin did not affect ovarian reserve or fertility but did decrease some senescence markers in the ovary.

Fisetin modulates the gut microbiota alongside biomarkers of senescence and inflammation in a DSS-induced murine model of colitis.

Colitis, a subtype of inflammatory bowel disease (IBD), is a multifactorial disorder characterized by chronic inflammation of the colon. Among various experimental models used in the study of IBD, the chemical colitogenic dextran sulfate sodium (DSS) is most commonly employed to induce colitis in vivo. In the search for new therapeutic strategies, Fisetin, a flavonoid found in many fruits and vegetables, has recently garnered attention for its senolytic properties. Female mice were administered 2.5% DSS in sterile drinking water and were subsequently treated with Fisetin or vehicle by oral gavage. DSS significantly upregulated beta-galactosidase activity in colonic proteins, while Fisetin remarkably inhibited its activity to baseline levels. Particularly, qPCR revealed that the senescence and inflammation markers Vimentin and Ptgs2 were elevated by DSS exposure with Fisetin treatment inhibiting the expression of p53, Bcl2, Cxcl1, and Mcp1, indicating that the treatment reduced senescent cell burden in the DSS targeted intestine. Alongside, senescence and inflammation associated miRNAs miR-149-5p, miR-96-5p, miR-34a-5p, and miR-30e-5p were significantly inhibited by DSS exposure and restored by Fisetin treatment, revealing novel targets for the treatment of IBDs. Metagenomics was implemented to assess impacts on the microbiota, with DSS increasing the prevalence of bacteria in the phyla Bacteroidetes. Meanwhile, Fisetin restored gut health through increased abundance of Akkermansia muciniphila, which is negatively correlated with senescence and inflammation. Our study suggests that Fisetin mitigates DSS-induced colitis by targeting senescence and inflammation and restoring beneficial bacteria in the gut indicating its potential as a therapeutic intervention for IBDs.

Effects of calorie, protein, and branched chain amino acid restriction on ovarian aging in mice.

Calorie restriction (CR) is an intervention that promotes longevity and preserves the ovarian reserve. Some studies have observed that the positive impacts of CR can be linked to restriction of protein (PR) and branched-chain amino acids (BCAAs) independent of calorie intake. The aim of this study was to compare the effects of protein and BCAA restriction to 30% CR on the ovarian reserve of female mice. For this, 3 month-old C57BL/6 female mice (n = 35) were randomized into four groups for four months dietary interventions including: control group (CTL; n = 8), 30% CR (CR; n = 9), protein restriction (PR; n = 9) and BCAA restriction (BCAAR; n = 9). Body mass gain, body composition, food intake, serum levels of BCAAs, ovarian reserve and estrous cyclicity were evaluated. We observed that CR, protein and BCAA restriction prevented weight gain and changed body composition compared to the CTL group. The BCAA restriction did not affect the ovarian reserve, while both PR and CR prevented activation of primordial follicles. This prevention occurred in PR group despite the lack of reduction of calorie intake compared to CTL group, and CR did not reduce protein intake in levels similar to the PR group. BCAA restriction resulted in increased calorie intake compared to CTL and PR mice, but only PR reduced serum BCAA levels compared to the CTL group. Our data indicates that PR has similar effects to CR on the ovarian reserve, whereas BCAA restriction alone did not affect it.

Effect of calorie restriction on redox status during chemically induced estropause in female mice.

In females, there is a continuous decline of the ovarian reserve with age, which results in menopause in women or estropause in mice. Loss of ovarian function results in metabolic alterations in mice and women. Based on this, we aimed to evaluate the effect of caloric restriction (CR) on redox status and metabolic changes in chemically induced estropause in mice. For this, mice were divided into four groups (n = 10): cyclic ad libitum (AL), cyclic 30% CR, AL estropause, and estropause 30% CR. Estropause was induced using 4-vinylcyclohexene diepoxide (VCD) for 20 consecutive days in 2-month-old females. The CR protocol started at 5 months of age and the treatments lasted for 4 months. The CR females gained less body weight than AL females (p < 0.001) and had lower glycemic curves in response to glucose tolerance test (GTT). The AL estropause females had the highest body weight and body fat, despite having lower food intake. However, the estropause females on 30% CR lost the most body weight and had the lowest amount of body fat compared to all groups. The effect of 30% CR on redox status in fat and liver tissue was similar for cyclic and estropause females. Interestingly, estropause decreased ROS in adipose tissue, while increasing it in the liver. No significant effects of CR on redox status were observed. Chemically induced estropause did not influence the response to 30% CR on glucose tolerance and redox status; however, weight loss was exarcebated compared to cyclic females.

Chronological and reproductive aging-associated changes in resistance to oxidative stress in post-reproductive female mice.

Effort toward reproduction is often thought to negatively influence health and survival. Reproduction has been shown to influence metabolism, but the pathways and mechanisms have yet to be thoroughly elucidated. In the current experiments, our aim was to dissect the role of young and old ovarian tissues in the response to oxidative stress, through changes in liver oxidative stress response proteins. Liver proteins were analyzed in control mice at 4, 13, and 27 months of age and compared to 23-month-old mice which received young ovarian tissue transplants (intact or follicle-depleted) at 13 months of age. In control mice, of the 29 oxidative stress response proteins measured, 31% of the proteins decreased, 52% increased, and 17% were unchanged from 13 to 27 months. The greatest changes were seen during the period of reproductive failure, from 4 to 13 months of age. In transplanted mice, far more proteins were decreased from 13 to 23 months (93% in follicle-containing young ovary recipients; 62% in follicle-depleted young ovary recipients). Neither transplant group reflected changes seen in control mice between 13 and 27 months. Estradiol levels in transplant recipient mice were not increased compared with age-matched control mice. The current results suggest the presence of a germ cell- and estradiol-independent ovarian influence on aging-associated changes in the response to oxidative stress, which is manifest differently in reproductive-aged adults and post-reproductive-aged mice. The results presented here separate chronological and ovarian aging and the influence of estradiol in the response to aging-associated oxidative stress and support a novel, estradiol-independent role for the ovary in female health and survival.

Unique trans-kingdom microbiome structural and functional signatures predict cognitive decline in older adults.

The prevalence of age-related cognitive disorders/dementia is increasing, and effective prevention and treatment interventions are lacking due to an incomplete understanding of aging neuropathophysiology. Emerging evidence suggests that abnormalities in gut microbiome are linked with age-related cognitive decline and getting acceptance as one of the pillars of the Geroscience hypothesis. However, the potential clinical importance of gut microbiome abnormalities in predicting the risk of cognitive decline in older adults is unclear. Till now the majority of clinical studies were done using 16S rRNA sequencing which only accounts for analyzing bacterial abundance, while lacking an understanding of other crucial microbial kingdoms, such as viruses, fungi, archaea, and the functional profiling of the microbiome community. Utilizing data and samples of older adults with mild cognitive impairment (MCI; n = 23) and cognitively healthy controls (n = 25). Our whole-genome metagenomic sequencing revealed that the gut of older adults with MCI harbors a less diverse microbiome with a specific increase in total viruses and a decrease in bacterial abundance compared with controls. The virome, bacteriome, and microbial metabolic signatures were significantly distinct in subjects with MCI versus controls. Selected bacteriome signatures show high predictive potential of cognitive dysfunction than virome signatures while combining virome and metabolic signatures with bacteriome boosts the prediction power. Altogether, the results from our pilot study indicate that trans-kingdom microbiome signatures are significantly distinct in MCI gut compared with controls and may have utility for predicting the risk of developing cognitive decline and dementia- debilitating public health problems in older adults.

Dasatinib and quercetin increase testosterone and sperm concentration in mice.

Cellular senescence is a defense mechanism to arrest proliferation of damaged cells. The number of senescent cells increases with age in different tissues and contributes to the development of age-related diseases. Old mice treated with senolytics drugs, dasatinib and quercetin (D+Q), have reduced senescent cells burden. The aim of this study was to evaluate the effects of D+Q on testicular function and fertility of male mice. Mice (n = 9/group) received D (5 mg kg-1) and Q (50 mg kg-1) via gavage every moth for three consecutive days from 3 to 8 months of age. At 8 months mice were breed with young non-treated females and euthanized. The treatment of male mice with D+Q increased serum testosterone levels and sperm concentration and decreased abnormal sperm morphology. Sperm motility, seminiferous tubule morphometry, testicular gene expression and fertility were not affected by treatment. There was no effect of D+Q treatment in ß-galactosidase activity and in lipofuscin staining in testes. D+Q treatment also did not affect body mass gain and testes mass. In conclusion, D+Q treatment increased serum testosterone levels and sperm concentration and decreased abnormal sperm morphology, however did not affect fertility. Further studies with older mice and different senolytics are necessary to elucidate the effects in the decline of sperm output (quality and quantity) associated with aging.

Cellular senescence in skin-related research: Targeted signaling pathways and naturally occurring therapeutic agents.

Despite the growing interest by researchers into cellular senescence, a hallmark of cellular aging, its role in human skin remains equivocal. The skin is the largest and most accessible human organ, reacting to the external and internal environment. Hence, it is an organ of choice to investigate cellular senescence and to target root-cause aging processes using senolytic and senomorphic agents, including naturally occurring plant-based derivatives. This review presents different aspects of skin cellular senescence, from physiology to pathology and signaling pathways. Cellular senescence can have both beneficial and detrimental effects on the skin, indicating that both prosenescent and antisenescent therapies may be desirable, based on the context. Knowledge of molecular mechanisms involved in skin cellular senescence may provide meaningful insights for developing effective therapeutics for senescence-related skin disorders, such as wound healing and cosmetic skin aging changes.

Ovarian aging in humans: potential strategies for extending reproductive lifespan.

Ovarian reserve is a term used to estimate the total number of immature follicles present in the ovaries. Between birth and menopause, there is a progressive decrease in the number of ovarian follicles. Ovarian aging is a continuous physiological phenomenon, with menopause being the clinical mark of the end of ovarian function. Genetics, measured as family history for age at the onset of menopause, is the main determinant. However, physical activity, diet, and lifestyle are important factors that can influence the age of menopause. The low estrogen levels after natural or premature menopause increased the risk for several diseases, resulting in increased mortality risk. Besides that, the decreasing ovarian reserve is associated to reduced fertility. In women with infertility undergoing in vitro fertilization, reduced markers of ovarian reserve, including antral follicular count and anti-Mullerian hormone, are the main indicators of reduced chances of becoming pregnant. Therefore, it becomes clear that the ovarian reserve has a central role in women's life, affecting fertility early in life and overall health later in life. Based on this, the ideal strategy for delaying ovarian aging should have the following characteristics: (1) be initiated in the presence of good ovarian reserve; (2) maintained for a long period; (3) have an action on the dynamics of primordial follicles, controlling the rate of activation and atresia; and (4) safe use in pre-conception, pregnancy, and lactation. In this review, we therefore discuss some of these strategies and its feasibility for preventing a decline in the ovarian reserve.

microRNA-449a reduces growth hormone-stimulated senescent cell burden through PI3K-mTOR signaling.

Cellular senescence, a hallmark of aging, has been implicated in the pathogenesis of many major age-related disorders, including neurodegeneration, atherosclerosis, and metabolic disease. Therefore, investigating novel methods to reduce or delay the accumulation of senescent cells during aging may attenuate age-related pathologies. microRNA-449a-5p (miR-449a) is a small, noncoding RNA down-regulated with age in normal mice but maintained in long-living growth hormone (GH)-deficient Ames Dwarf (df/df) mice. We found increased fibroadipogenic precursor cells, adipose-derived stem cells, and miR-449a levels in visceral adipose tissue of long-living df/df mice. Gene target analysis and our functional study with miR-449a-5p have revealed its potential as a serotherapeutic. Here, we test the hypothesis that miR-449a reduces cellular senescence by targeting senescence-associated genes induced in response to strong mitogenic signals and other damaging stimuli. We demonstrated that GH downregulates miR-449a expression and accelerates senescence while miR-449a upregulation using mimetics reduces senescence, primarily through targeted reduction of p16Ink4a, p21Cip1, and the PI3K-mTOR signaling pathway. Our results demonstrate that miR-449a is important in modulating key signaling pathways that control cellular senescence and the progression of age-related pathologies.

GH deficiency confers protective advantages against Alzheimer's disease through rescued miRNA expression profile in APP/PS1 mice.

Alzheimer's disease (AD) is the most common form of dementia, affecting approximately 6.5 million Americans age 65 or older. AD is characterized by increased cognitive impairment and treatment options available provide minimal disease attenuation. Additionally, diagnostic methods for AD are not conclusive with definitive diagnoses requiring postmortem brain evaluations. Therefore, miRNAs, a class of small, non-coding RNAs, have garnered attention for their ability to regulate a variety of mRNAs and their potential to serve as both therapeutic targets and biomarkers of AD. Several miRNAs have already been implicated with AD and have been found to directly target genes associated with AD pathology. The APP/PS1 mice is an AD model that expresses the human mutated form of the amyloid precursor protein (APP) and presenilin-1 (PS1) genes. In a previous study, it was identified that crossing long-living growth hormone (GH)-deficient Ames dwarf (df/df) mice with APP/PS1 mice provided protection from AD through a reduction in IGF-1, amyloid-ß (Aß) deposition, and gliosis. Hence, we hypothesized that changes in the expression of miRNAs associated with AD mediated such benefits. To test this hypothesis, we sequenced miRNAs in hippocampi of df/df, wild type (+ / +), df/ + /APP/PS1 (phenotypically normal APP/PS1), and df/df/APP/PS1 mice. Results of this study demonstrated significantly upregulated and downregulated miRNAs between df/df/APP/PS1 and df/ + /APP/PS1 mice that suggest the df/df mutation provides protection from AD progression. Additionally, changes in miRNA expression with age were identified in both df/df and wild-type mice as well as df/df/APP/PS1 and APP/PS1 mice, with predictive functional roles in the Pi3k-AKT/mTOR/FOXO pathways potentially contributing to disease pathogenesis.