Liver sexual dimorphism in key signaling pathways across the rat life course
Ontology highlight
ABSTRACT: Introduction: At the molecular level, cellular aging involves changes in multiple gene pathways, which can produce many aging phenotypes. In the liver, senescence changes lead to impaired hepatic function. We hypothesized that the natural hepatic aging process is driven by sex-dependent mechanisms. Purpose: We studied our well-established model of aging in which we have previously determined aging of metabolism, reproduction and endocrine systems. We performed liver transcriptomics (RNA-seq) on male and female rats at 110 and 650 days (d) fed with normal rat chow to determine changes key signaling pathways related to senescence processes. Methods: To identify the functional F1 liver changes due to natural aging processes, we evaluated the differentially expressed genes (DEGs) between 650d and 110d in males and females, with separate pairwise comparisons due to the marked differences. Genes were filtered based on ?1.4 fold change (FC) and nominal P value <0.05 (Studentエs t-test). Results: We found that the natural liver aging process shows sex-differences. RNA-seq revealed more male (3,967) than female (283) differentially expressed genes (DEG) and pathways over the 110d to 650d period studied. Cell cycle pathway signaling in males was accompanied by decreased protein and gene expression of key genes (CDK2, CDK4, Cycd and PCNA) and an increase of p57 at 650d vs. 110d. In females, protein and gene expression of cell growth regulators such as p15 and p21, that inhibit cell cycle G1 progression were increased. Moreover, additionally the cell senescence pathway showed sexual dimorphism in liver gene regulation. Conclusions: Our results demonstrate how the natural aging process affects the liver transcriptome signature in a sex-dependent manner, specifically in cell cycle and cell senescence pathways, pathways that contribute in a major fashion to the development of aging-induced liver diseases. Understanding cellular senescence pathways involved in the natural aging process will aid evaluation of mechanisms associated with altered aging and frailty trajectories.
Project description:Immune checkpoint bloackade (ICB)-based or natural cancer immune responses largely eliminate tumours. Yet, they require additional mechanisms to arrest those cancer cells that are not rejected. Cytokine-induced senescence (CIS) can stably arrest cancer cells, suggesting that interferon-dependent induction of senescence-inducing cell cycle regulators is needed to control those cancer cells that escape from killing. Here we report in two different cancers sensitive to T cell-mediated rejection, we show that deletion of the senescence-inducing cell cycle regulators p16Ink4a/p19Arf (Cdkn2a) or p21Cip1 (Cdkn1a) in the tumour cells abrogated both, the natural and the ICB-induced cancer immune control. Also in humans, melanoma metastases that progressed rapidly during ICB have losses of senescence-inducing genes and amplifications of senescence inhibitors. Metastatic cells also resist CIS. Such genetic and functional alterations are infrequent in metastatic melanomas regressing during ICB. Thus, activation of tumour-intrinsic, senescence-inducing cell cycle regulators is required to stably arrest those cancer cells that escape from eradication.
Project description:Cellular senescence disables the proliferation of damaged cells and it is relevant for cancer and aging. Here, we show that cellular senescence occurs during mammalian embryonic development. Specifically, we have focused on the mouse regressing mesonephros and the endolymphatic sac of the inner ear. Senescence is characterized by SAM-NM-2G activity, heterochromatinization, and proliferative arrest. Mechanistically, developmentally-programmed senescence at the mesonephros and endolymphatic sac is strictly dependent on p21, but independent of DNA damage, p53 or other cell cycle inhibitors, and it is regulated by the TGFM-NM-2/SMAD and PI3K/FOXO pathways. Developmentally-programmed senescence is followed by macrophage infiltration and clearance of senescent cells. Abrogation of senescence by p21 deletion is only partially compensated by apoptosis and originates detectable developmental abnormalities. Importantly, high levels of p21 are also associated to the regressing mesonephros and endolymphatic sac in human embryos. These findings place cellular senescence as a relevant morphogenic process during embryonic development. We microdissected mesonephric tubules from senescent (WT) and non-senescent (p21-null) embryos to get information about this new senescence that occurs during embryogenesis.
Project description:A heterozygous missense mutation producing a variant of the islet β-cell-enriched MAFA transcription factor (p.Ser64Phe (S64F)) was identified in patients who developed adult-onset, β-cell dysfunction (diabetes or insulinomatosis), with men more prone to diabetes than women. This mutation engenders increased stability to the normally unstable MAFA protein. To obtain insight into how this variant impacts β cell function, we developed a mouse model expressing S64F MafA and found sex-dependent phenotypes, with heterozygous mutant males (MafAS64F/+) displaying impaired glucose tolerance while females were slightly hypoglycemic with improved blood glucose clearance. Only MafAS64F/+ males showed transiently higher MafA protein levels preceding the onset of glucose intolerance and sex-dependent, differential expression of genes involved in Ca2+ signaling, DNA damage, aging, and senescence. Functional changes in islet Ca2+ handling and signs of islet aging and senescence processes were uniquely observed in male animals. In addition, MAFAS64F production in male human β cells accelerated cellular senescence and increased production of senescence-associated secretory proteins compared to cells expressing MAFAWT. Together, these results implicate a conserved mechanism of accelerated islet aging and senescence in promoting diabetes in MAFAS64F carriers in a sex-dependent manner.
Project description:Aging is a slow and progressive natural process that compromises the normal functions of cells, tissues, organs and systems. The aging of the hypothalamic median eminence (ME), a structural gate linking neural and endocrine systems, may impair hormone release, energy homeostasis and central sensing of circulating molecules, leading to systemic and reproductive aging. However, the molecular and cellular features of ME aging remain largely unknown. Here we describe the transcriptional landscape of young and middle-aged mouse ME at single-cell resolution, revealing the common and cell-type-specific transcriptional changes with age. The transcriptional changes in cell-intrinsic programs, cell-cell crosstalk and cell-extrinsic factors highlight five molecular features of ME aging and also implicate several potentially druggable targets at cellular, signaling and molecular levels. Importantly, our results suggest that vascular and leptomeningeal cells may lead the asynchronized aging process among diverse cell types and drive local inflammation and cellular senescence via a unique secretome. Together, our study uncovers how intrinsic and extrinsic features of each cell type in the hypothalamic ME are changed by the aging process, which will facilitate our understanding of brain aging and provide clues for efficient anti-aging intervention at the middle-aged stage.
Project description:Cellular senescence is a dynamic tumor suppression mechanism that limits the proliferation of impaired cells, by executing a stable cell cycle arrest. Understanding the molecular pathways and regulatory circuits that are involved in the process of senescence is presently incomplete. In this study, we determined the changes in gene expression during the establishment of replicative senescence, by comparing the expression profiles of young and senescent human umbilical vein endothelial cells (HUVECs). Exploration of array data using ingenuity pathway analysis showed that genes involved in cell cycle regulation, cellular assembly and organization, DNA replication, recombination and repair were significantly down regulated during senescence.
Project description:Senescence is a well-known cellular event characterized by specific markers like a permanent cell proliferation arrest and the secretion of messenger molecules forming the Senescence-Associated Secretory Phenotype (SASP). The SASP composition depends on many factors such as the cell type or the nature of the stress that induced senescence. Since the skin constitutes a barrier with the external environment, it is particularly subjected to different types of stresses and thus to premature cellular aging. The dicarbonyl compounds glyoxal and methylglyoxal are precursors of Advanced Glycation End-products (AGEs), known to be a feature of normal and pathological aging. In this study, we have demonstrated that glyoxal provokes oxidative stress by increasing ROS and AGEs levels and can induce senescence in human keratinocytes. An “early-stage” senescence phenotype characterized by a cell cycle arrest mediated by the AKT-FOXO3-p27KIP1 pathway and a “late-stage” senescence maintained by the p16INK4/pRb pathway were evidenced. Moreover, we characterized the resulting secretory phenotype during early senesecence by mass spectrometry. Our study provides evidence that glyoxal can affect keratinocyte function and act as a driver of human skin aging. Hence, senotherapeutics aimed at modulating glyoxal-associated senescence phenotype could be relevant to prevent the aging process in skin.
Project description:Cellular senescence is a program of permanent cell cycle arrest, apoptosis resistance, and cytokine release induced by stress exposure in mammalian cells. Landmark studies in laboratory mice have established master senescence regulators, including p16INK4a, p21, NF-kB, p53, and C/EBPβ. To discover other molecular players in cellular senescence, we developed an approach that harnessed the natural divergence between distant mouse species. We found that senescent primary cells from the Algerian mouse Mus spretus expressed a distinct, and largely muted, regulatory program relative to that of laboratory M. musculus. We pinpointed which of these interspecies expression changes during senescence were under cis-regulatory control, via allele-specific expression profiling. Then, in silico, we associated the latter with sequence variants in transcription factor binding sites. Among the emergent candidate senescence regulators, we chose a little-studied cell cycle factor, USF2, for molecular validation. In acute irradiation experiments, cells lacking USF2 exhibited compromised DNA damage repair and response. Longer-term senescent cultures without USF2 mounted an exaggerated senescence regulatory program—shutting down cell cycle and DNA repair pathways, and turning up cytokine expression, more avidly than wild-type. We interpret these findings under a model of pro-repair, anti-senescence regulatory function by native USF2. Our study affords new insights into the mechanisms by which cells commit to senescence, and serves as a validated proof of concept for natural variation-based regulator screens.
Project description:Aging, a risk factor for many diseases, is largely attributable to cell senescence and impaired mitochondrial function. Here, we used connectivity map (CMAP) to predict the anti-aging effects of drugs based on age-related transcriptomic signatures. We found the kinase inhibitor GW8510 can extend lifespan of yeast, and C57BL/6J or ICR mice by 92.18%, 31.9%, and 142.9%, respectively. Mechanistically, GW8510 can ameliorate cellular senescence by enhancing mitochondrial function, decreasing SA-β-gal staining, p21 and SASP marker expression, and rescues age-related histomorphological changes in mouse hippocampus, heart, kidney and liver. In yeast, the action of GW8510 is dependent on STE20, and in human cells, GW8510 acts through various pathways such as SRC, PAKs, and JAKs. Furthermore, inhibiting these genes can delay cellular senescence. This work provides a valuable resource for mechanistic aging studies and suggests strong clinical potential for GW8510.
Project description:Verlingue2016 - Signalling pathway that
control S-phase entry and geroconversion - Boolean Model
This model is described in the article:
A comprehensive approach to
the molecular determinants of lifespan using a Boolean model of
geroconversion.
Verlingue L, Dugourd A, Stoll G,
Barillot E, Calzone L, Londoño-Vallejo A.
Aging Cell 2016 Sep; :
Abstract:
Altered molecular responses to insulin and growth factors
(GF) are responsible for late-life shortening diseases such as
type-2 diabetes mellitus (T2DM) and cancers. We have built a
network of the signaling pathways that control S-phase entry
and a specific type of senescence called geroconversion. We
have translated this network into a Boolean model to study
possible cell phenotype outcomes under diverse molecular
signaling conditions. In the context of insulin resistance, the
model was able to reproduce the variations of the senescence
level observed in tissues related to T2DM's main morbidity and
mortality. Furthermore, by calibrating the pharmacodynamics of
mTOR inhibitors, we have been able to reproduce the
dose-dependent effect of rapamycin on liver degeneration and
lifespan expansion in wild-type and HER2-neu mice. Using the
model, we have finally performed an in silico prospective
screen of the risk-benefit ratio of rapamycin dosage for
healthy lifespan expansion strategies. We present here a
comprehensive prognostic and predictive systems biology tool
for human aging.
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Project description:Here we found Rosa roxburghii fruit extracts effectively increase TERT expression and telomerase activity in cultured human mesenchymal stem cells. Both Rosa roxburghii fruit extracts by freeze drying and spray drying methods increase the activity of telomerase. Rosa roxburghii fruit freeze drying extracts is able to reduce reactive oxygen species levels, enhance SOD activity and resistance to oxidative stress, and reduce DNA damage caused by oxidative stress or radiation. Rosa roxburghii fruit extracts promoted cell proliferation, improved senescent cell morphology, delayed replicative cellular senescence, attenuated cell cycle supressors and alleviated the senescence-associated secretory phenotype. Transcriptome and metabolic profilings found that Rosa roxburghii fruit extract promote cell proliferation and DNA repair pathways, decreased triglycerides as well. Overall, we provided a theoretical basis for the application of Rosa roxburghii fruit as an anti-aging natural product.