Senescence-related signatures predict prognosis and response to immunotherapy in colon cancer.

Background: Colorectal cancer (CRC) is one of the most common cancers. Cellular senescence plays a vital role in carcinogenesis by activating many pathways. In this study, we aimed to identify biomarkers for predicting the survival and recurrence of CRC through cellular senescence-related genes. Methods: Utilizing The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, RNA-sequencing data and clinical information for CRC were collected. A risk model for predicting overall survival was established based on five differentially expressed genes using least absolute shrinkage and selection operator-Cox regression (LASSO-Cox regression), receiver operating characteristic (ROC), and Kaplan-Meier analyses. The study also delved into both the tumor microenvironment and the response to immunotherapy. Moreover, we gathered clinical sample data from our center in order to confirm the findings of public database analysis. Results: Through ROC and Kaplan-Meier analyses, a risk model was developed using five cellular senescence-related genes [i.e., CDKN2A, SERPINE1, SNAI1, CXCL1, and ETS2] to categorize patients into high- and low-risk groups. In the TCGA-colon adenocarcinoma (COAD) and GEO-COAD cohorts, the high-risk group was associated with a bleaker forecast (P<0.05), immune cell inactivation, and insensitivity to immunotherapy in IMvigor210 database (http://research-pub.gene.com/IMvigor210CoreBiologies/). Clinical samples were then used to confirm that ETS2 and CDKN2A could serve as independent prognostic biomarkers in CRC. Conclusions: Gene signatures related to cellular senescence, specifically involving CDKN2A and ETS2, are emerging as promising biomarkers for predicting CRC prognosis and guiding immunotherapy.

Hsa-miR-134-5p predicts cardiovascular risk in circulating mononuclear cells and improves angiogenic action of senescent endothelial progenitor cells.

This research explores the role of microRNA in senescence of human endothelial progenitor cells (EPCs) induced by replication. Hsa-miR-134-5p was found up-regulated in senescent EPCs where overexpression improved angiogenic activity. Hsa-miR-134-5p, which targeted transforming growth factor ß-activated kinase 1-binding protein 1 (TAB1) gene, down-regulated TAB1 protein, and inhibited phosphorylation of p38 mitogen-activated protein kinase (p38) in hsa-miR-134-5p-overexpressed senescent EPCs. Treatment with siRNA specific to TAB1 (TAB1si) down-regulated TAB1 protein and subsequently inhibited p38 activation in senescent EPCs. Treatment with TAB1si and p38 inhibitor, respectively, showed angiogenic improvement. In parallel, transforming growth factor Beta 1 (TGF-ß1) was down-regulated in hsa-miR-134-5p-overexpressed senescent EPCs and addition of TGF-ß1 suppressed the angiogenic improvement. Analysis of peripheral blood mononuclear cells (PBMCs) disclosed expression levels of hsa-miR-134-5p altered in adult life, reaching a peak before 65 years, and then falling in advanced age. Calculation of the Framingham risk score showed the score inversely correlates with the hsa-miR-134-5p expression level. In summary, hsa-miR-134-5p is involved in the regulation of senescence-related change of angiogenic activity via TAB1-p38 signalling and via TGF-ß1 reduction. Hsa-miR-134-5p has a potential cellular rejuvenation effect in human senescent EPCs. Detection of human PBMC-derived hsa-miR-134-5p predicts cardiovascular risk.

Identifying and evaluating a disulfidptosis-related gene signature to predict prognosis in colorectal adenocarcinoma patients.

Disulfidptosis, a regulated form of cell death, has been recently reported in cancers characterized by high SLC7A11 expression, including invasive breast carcinoma, lung adenocarcinoma, and hepatocellular carcinoma. However, its role in colon adenocarcinoma (COAD) has been infrequently discussed. In this study, we developed and validated a prognostic model based on 20 disulfidptosis-related genes (DRGs) using LASSO and Cox regression analyses. The robustness and practicality of this model were assessed via a nomogram. Subsequent correlation and enrichment analysis revealed a relationship between the risk score, several critical cancer-related biological processes, immune cell infiltration, and the expression of oncogenes and cell senescence-related genes. POU4F1, a significant component of our model, might function as an oncogene due to its upregulation in COAD tumors and its positive correlation with oncogene expression. In vitro assays demonstrated that POU4F1 knockdown noticeably decreased cell proliferation and migration but increased cell senescence in COAD cells. We further investigated the regulatory role of the DRG in disulfidptosis by culturing cells in a glucose-deprived medium. In summary, our research revealed and confirmed a DRG-based risk prediction model for COAD patients and verified the role of POU4F1 in promoting cell proliferation, migration, and disulfidptosis.

Wheat NAC transcription factor NAC5-1 is a positive regulator of senescence.

Wheat (Triticum aestivum L.) is an important source of both calories and protein in global diets, but there is a trade-off between grain yield and protein content. The timing of leaf senescence could mediate this trade-off as it is associated with both declines in photosynthesis and nitrogen remobilization from leaves to grain. NAC transcription factors play key roles in regulating senescence timing. In rice, OsNAC5 expression is correlated with increased protein content and upregulated in senescing leaves, but the role of the wheat ortholog in senescence had not been characterized. We verified that NAC5-1 is the ortholog of OsNAC5 and that it is expressed in senescing flag leaves in wheat. To characterize NAC5-1, we combined missense mutations in NAC5-A1 and NAC5-B1 from a TILLING mutant population and overexpressed NAC5-A1 in wheat. Mutation in NAC5-1 was associated with delayed onset of flag leaf senescence, while overexpression of NAC5-A1 was associated with slightly earlier onset of leaf senescence. DAP-seq was performed to locate transcription factor binding sites of NAC5-1. Analysis of DAP-seq and comparison with other studies identified putative downstream target genes of NAC5-1 which could be associated with senescence. This work showed that NAC5-1 is a positive transcriptional regulator of leaf senescence in wheat. Further research is needed to test the effect of NAC5-1 on yield and protein content in field trials, to assess the potential to exploit this senescence regulator to develop high-yielding wheat while maintaining grain protein content.

Stretch-induced damage in endothelial monolayers.

Endothelial cells are constantly exposed to mechanical stimuli, of which mechanical stretch has shown various beneficial or deleterious effects depending on whether loads are within physiological or pathological levels, respectively. Vascular properties change with age, and on a cell-scale, senescence elicits changes in endothelial cell mechanical properties that together can impair its response to stretch. Here, high-rate uniaxial stretch experiments were performed to quantify and compare the stretch-induced damage of monolayers consisting of young, senescent, and aged endothelial populations. The aged and senescent phenotypes were more fragile to stretch-induced damage. Prominent damage was detected by immunofluorescence and scanning electron microscopy as intercellular and intracellular void formation. Damage increased proportionally to the applied level of deformation and, for the aged and senescent phenotype, induced significant detachment of cells at lower levels of stretch compared to the young counterpart. Based on the phenotypic difference in cell-substrate adhesion of senescent cells indicating more mature focal adhesions, a discrete network model of endothelial cells being stretched was developed. The model showed that the more affine deformation of senescent cells increased their intracellular energy, thus enhancing the tendency for cellular damage and impending detachment. Next to quantifying for the first-time critical levels of endothelial stretch, the present results indicate that young cells are more resilient to deformation and that the fragility of senescent cells may be associated with their stronger adhesion to the substrate.

Long-term culture of patient-derived mammary organoids in non-biogenic electrospun scaffolds for identifying metalloprotein and motor protein activities in aging and senescence.

We recently identified TMEM230 as a master regulator of the endomembrane system of cells. TMEM230 expression is necessary for promoting motor protein dependent intracellular trafficking of metalloproteins for cellular energy production in mitochondria. TMEM230 is also required for transport and secretion of metalloproteinases for autophagy and phagosome dependent clearance of misfolded proteins, defective RNAs and damaged cells, activities that decline with aging. This suggests that aberrant levels of TMEM230 may contribute to aging and regain of proper levels may have therapeutic applications. The components of the endomembrane system include the Golgi complex, other membrane bound organelles, and secreted vesicles and factors. Secreted cellular components modulate immune response and tissue regeneration in aging. Upregulation of intracellular packaging, trafficking and secretion of endosome components while necessary for tissue homeostasis and normal wound healing, also promote secretion of pro-inflammatory and pro-senescence factors. We recently determined that TMEM230 is co-regulated with trafficked cargo of the endomembrane system, including lysosome factors such as RNASET2. Normal tissue regeneration (in aging), repair (following injury) and aberrant destructive tissue remodeling (in cancer or autoimmunity) likely are regulated by TMEM230 activities of the endomembrane system, mitochondria and autophagosomes. The role of TMEM230 in aging is supported by its ability to regulate the pro-inflammatory secretome and senescence-associated secretory phenotype in tissue cells of patients with advanced age and chronic disease. Identifying secreted factors regulated by TMEM230 in young patients and patients of advanced age will facilitate identification of aging associated targets that aberrantly promote, inhibit or reverse aging. Ex situ culture of patient derived cells for identifying secreted factors in tissue regeneration and aging provides opportunities in developing therapeutic and personalized medicine strategies. Identification and validation of human secreted factors in tissue regeneration requires long-term stabile scaffold culture conditions that are different from those previously reported for cell lines used as cell models for aging. We describe a 3 dimensional (3D) platform utilizing non-biogenic and non-labile poly ε-caprolactone scaffolds that supports maintenance of long-term continuous cultures of human stem cells, in vitro generated 3D organoids and patient derived tissue. Combined with animal component free culture media, non-biogenic scaffolds are suitable for proteomic and glycobiological analyses to identify human factors in aging. Applications of electrospun nanofiber technologies in 3D cell culture allow for ex situ screening and the development of patient personalized therapeutic strategies and predicting their effectiveness in mitigating or promoting aging.

Topical application of a BCL-2 inhibitor ameliorates imiquimod-induced psoriasiform dermatitis by eliminating senescent cells.

BACKGROUND: Psoriasis is an inflammatory skin disease with unclear pathogenesis and unmet therapeutic needs. OBJECTIVE: To investigate the role of senescent CD4+ T cells in psoriatic lesion formation and explore the application of senolytics in treating psoriasis. METHODS: We explored the expression levels of p16INK4a and p21, classical markers of cellular senescence, in CD4+ T cells from human psoriatic lesions and imiquimod (IMQ)-induced psoriatic lesions. We prepared a senolytic gel using B-cell lymphoma 2 (BCL-2) inhibitor ABT-737 and evaluated its therapeutic efficacy in treating psoriasis. RESULTS: Using multispectrum immunohistochemistry (mIHC) staining, we detected increased expression levels of p16INK4a and p21 in CD4+ T cells from psoriatic lesions. After topical application of ABT-737 gel, significant alleviation of IMQ-induced psoriatic lesions was observed, with milder pathological alterations. Mechanistically, ABT-737 gel significantly decreased the percentage of senescent cells, expression of T cell receptor (TCR) α and ß chains, and expression of Tet methylcytosine dioxygenase 2 (Tet2) in IMQ-induced psoriatic lesions, as determined by mIHC, high-throughput sequencing of the TCR repertoire, and RT-qPCR, respectively. Furthermore, the severity of psoriatic lesions in CD4creTet2f/f mice was milder than that in Tet2f/f mice in the IMQ-induced psoriasis model. CONCLUSION: We revealed the roles of senescent CD4+ T cells in developing psoriasis and highlighted the therapeutic potential of topical ABT-737 gel in treating psoriasis through the elimination of senescent cells, modulation of the TCR αß repertoire, and regulation of the TET2-Th17 cell pathway.

Cardiac and skeletal muscle manifestations in the G608G mouse model of Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS) is a rare premature aging disorder resulting from de novo mutations in the lamin A gene. Children with HGPS typically pass away in their teenage years due to cardiovascular diseases such as atherosclerosis, myocardial infarction, heart failure, and stroke. In this study, we characterized the G608G HGPS mouse model and explored cardiac and skeletal muscle function, along with senescence-associated phenotypes in fibroblasts. Homozygous G608G HGPS mice exhibited cardiac dysfunction, including decreased cardiac output and stroke volume, and impaired left ventricle relaxation. Additionally, skeletal muscle exhibited decreased isometric tetanic torque, muscle atrophy, and increased fibrosis. HGPS fibroblasts showed nuclear abnormalities, decreased proliferation, and increased expression of senescence markers. These findings provide insights into the pathophysiology of the G608G HGPS mouse model and inform potential therapeutic strategies for HGPS.

Empagliflozin attenuates epithelial to mesenchymal transition through senescence in peritoneal dialysis.

BACKGROUND: Epithelial to mesenchymal transition (EMT) is considered as one of the senescence processes; reportedly, anti-senescence therapies effectively reduce EMT. Some models have shown anti-senescence effects with the use of sodium-glucose cotransporter-2 (SGLT2) inhibitor. Therefore, our study investigated the anti-senescence effects of empagliflozin as a SGLT2 inhibitor in a peritoneal fibrosis model and their impact on EMT inhibition. METHODS: For in vitro study, human peritoneal mesothelial cells (HPMCs) were isolated and grown in a 96-well plate. The cell media were exchanged with serum-free M199 medium with D-Glucose, with or without empagliflozin. All animal experiments were carried out in male mice. Mice were randomly classified into three treatment groups based on peritoneal dialysis (PD) or empagliflozin. We evaluated changes in senescence and EMT markers in HPMCs and PD model. RESULTS: HPMCs treated with glucose transformed from cobble stone to spindle shape, resulting in EMT. Empagliflozin attenuated these morphologic changes. Reactive oxygen species production, DNA damage, senescence, and EMT markers were increased by glucose treatment; however, co-treatment with glucose and empagliflozin attenuated these changes. For the mice with PD, an increase in thickness, collagen deposition, staining for senescence or EMT markers of the parietal peritoneum was observed, which however, was attenuated by co-treatment with empagliflozin. p53, p21, and p16 increased in mice with PD compared to that in the control group; however, these changes were decreased by empagliflozin. CONCLUSION: Empagliflozin effectively attenuated glucose-induced EMT in HPMCs through a decrease in senescence. Co-treatment with empagliflozin improved peritoneal thickness and fibrosis in PD.

Inhibitory immune checkpoints suppress the surveillance of senescent cells promoting their accumulation with aging and in age-related diseases.

The accumulation of pro-inflammatory senescent cells within tissues is a common hallmark of the aging process and many age-related diseases. This modification has been called the senescence-associated secretory phenotype (SASP) and observed in cultured cells and in cells isolated from aged tissues. Currently, there is a debate whether the accumulation of senescent cells within tissues should be attributed to increased generation of senescent cells or to a defect in their elimination from aging tissues. Emerging studies have revealed that senescent cells display an increased expression of several inhibitory immune checkpoint ligands, especially those of the programmed cell death protein-1 (PD-1) ligand-1 (PD-L1) proteins. It is known that the PD-L1 ligands, especially those of cancer cells, target the PD-1 receptor of cytotoxic CD8+ T and natural killer (NK) cells disturbing their functions, e.g., evoking a decline in their cytotoxic activity and promoting their exhaustion and even apoptosis. An increase in the level of the PD-L1 protein in senescent cells was able to suppress their immune surveillance and inhibit their elimination by cytotoxic CD8+ T and NK cells. Senescent cells are known to express ligands for several inhibitory immune checkpoint receptors, i.e., PD-1, LILRB4, NKG2A, TIM-3, and SIRPα receptors. Here, I will briefly describe those pathways and examine whether these inhibitory checkpoints could be involved in the immune evasion of senescent cells with aging and age-related diseases. It seems plausible that an enhanced inhibitory checkpoint signaling can prevent the elimination of senescent cells from tissues and thus promote the aging process.

Soybean ethylene response factors GmENS1 and GmENS2 promote nodule senescence.

The final phase in root nodule development is nodule senescence. The mechanism underlying the initiation of nodule senescence requires further elucidation. Here, we investigated the intrinsic signals governing soybean (Glycine max L. Merr.) nodule senescence, uncovering ethylene as a key signal in this intricate mechanism. Two AP2/ERF transcription factor genes, GmENS1 and GmENS2 (Ethylene-responsive transcription factors required for Nodule Senescence), exhibit heightened expression levels in both aged nodules and nodules treated with ethylene. Overexpression of either GmENS1 or GmENS2 accelerated senescence in soybean nodules, whereas the knockout or knockdown of both genes delayed senescence and enhanced nitrogenase activity. Furthermore, our findings indicated that GmENS1 and GmENS2 directly bind to the promoters of GmNAC039, GmNAC018, and GmNAC030, encoding three NAC transcription factors essential for activating soybean nodule senescence. Notably, the nodule senescence process mediated by GmENS1 or GmENS2 overexpression was suppressed in the soybean nac039/018/030 triple mutant compared with the wild-type control. These data indicate GmENS1 and GmENS2 as pivotal transcription factors mediating ethylene-induced nodule senescence through the direct activation of GmNAC039/GmNAC018/GmNAC030 expression in soybean.

Roles of pigment epithelium-derived factor in exercise-induced suppression of senescence and its impact on lung pathology in mice.

Senescent cells contribute to tissue aging and underlie the pathology of chronic diseases. The benefits of eliminating senescent cells have been demonstrated in several disease models, and the efficacy of senolytic drugs is currently being tested in humans. Exercise training has been shown to reduce cellular senescence in several tissues; however, the mechanisms responsible remain unclear. We found that myocyte-derived factors significantly extended the replicative lifespan of fibroblasts, suggesting that myokines mediate the anti-senescence effects of exercise. A number of proteins within myocyte-derived factors were identified by mass spectrometry. Among these, pigment epithelium-derived factor (PEDF) exerted inhibitory effects on cellular senescence. Eight weeks of voluntary running increased Pedf levels in skeletal muscles and suppressed senescence markers in the lungs. The administration of PEDF reduced senescence markers in multiple tissues and attenuated the decline in respiratory function in the pulmonary emphysema mouse model. We also showed that blood levels of PEDF inversely correlated with the severity of COPD in patients. Collectively, these results strongly suggest that PEDF contributes to the beneficial effects of exercise, potentially suppressing cellular senescence and its associated pathologies.

Modulating in vitro lung fibroblast activation via senolysis of senescent human alveolar epithelial cells.

Idiopathic pulmonary fibrosis (IPF) is an age-related disease with poor prognosis and limited therapeutic options. Activation of lung fibroblasts and differentiation to myofibroblasts are the principal effectors of disease pathology, but damage and senescence of alveolar epithelial cells, specifically type II (ATII) cells, has recently been identified as a potential trigger event for the progressive disease cycle. Targeting ATII senescence and the senescence-associated secretory phenotype (SASP) is an attractive therapeutic strategy; however, translatable primary human cell models that enable mechanistic studies and drug development are lacking. Here, we describe a novel system of conditioned medium (CM) transfer from bleomycin-induced senescent primary alveolar epithelial cells (AEC) onto normal human lung fibroblasts (NHLF) that demonstrates an enhanced fibrotic transcriptional and secretory phenotype compared to non-senescent AEC CM treatment or direct bleomycin damage of the NHLFs. In this system, the bleomycin-treated AECs exhibit classical hallmarks of cellular senescence, including SASP and a gene expression profile that resembles aberrant epithelial cells of the IPF lung. Fibroblast activation by CM transfer is attenuated by pre-treatment of senescent AECs with the senolytic Navitoclax and AD80, but not with the standard of care agent Nintedanib or senomorphic JAK-targeting drugs (e.g., ABT-317, ruxolitinib). This model provides a relevant human system for profiling novel senescence-targeting therapeutics for IPF drug development.

Mutant androgen receptor induces neurite loss and senescence independently of ARE binding in a neuronal model of SBMA.

Spinal and bulbar muscular atrophy (SBMA) is a slowly progressing neuromuscular disease caused by a polyglutamine (polyQ)-encoding CAG trinucleotide repeat expansion in the androgen receptor (AR) gene, leading to AR aggregation, lower motor neuron death, and muscle atrophy. AR is a ligand-activated transcription factor that regulates neuronal architecture and promotes axon regeneration; however, whether AR transcriptional functions contribute to disease pathogenesis is not fully understood. Using a differentiated PC12 cell model of SBMA, we identified dysfunction of polyQ-expanded AR in its regulation of neurite growth and maintenance. Specifically, we found that in the presence of androgens, polyQ-expanded AR inhibited neurite outgrowth, induced neurite retraction, and inhibited neurite regrowth. This dysfunction was independent of polyQ-expanded AR transcriptional activity at androgen response elements (ARE). We further showed that the formation of polyQ-expanded AR intranuclear inclusions promoted neurite retraction, which coincided with reduced expression of the neuronal differentiation marker ß-III-Tubulin. Finally, we revealed that cell death is not the primary outcome for cells undergoing neurite retraction; rather, these cells become senescent. Our findings reveal that mechanisms independent of AR canonical transcriptional activity underly neurite defects in a cell model of SBMA and identify senescence as a pathway implicated in this pathology. These findings suggest that in the absence of a role for AR canonical transcriptional activity in the SBMA pathologies described here, the development of SBMA therapeutics that preserve this activity may be desirable. This approach may be broadly applicable to other polyglutamine diseases such as Huntington's disease and spinocerebellar ataxias.

Yeast Npl3 regulates replicative senescence outside of TERRA R-loop resolution and co-transcriptional processing.

Eukaryotic cells without telomerase experience progressively shorter telomeres with each round of cell division until cell cycle arrest is initiated, leading to replicative senescence. When yeast TLC1, which encodes the RNA template of telomerase, is deleted, senescence is accompanied by increased expression of TERRA (non-coding telomere repeat-containing RNA). Deletion of Npl3, an RNA-processing protein with telomere maintenance functions, accelerates senescence in tlc1Δ cells and significantly increases TERRA levels. Using genetic approaches, we set out to determine how Npl3 is involved in regulating TERRA expression and maintaining telomere homeostasis. Even though Npl3 regulates hyperrecombination, we found that Npl3 does not help resolve RNA:DNA hybrids formed during TERRA synthesis in the same way as RNase H1 and H2. Furthermore, Rad52 is still required for cells to escape senescence by telomere recombination in the absence of Npl3. Npl3 also works separately from the THO/TREX pathway for processing nascent RNA for nuclear export. However, deleting Dot1, a histone methyltransferase involved in tethering telomeres to the nuclear periphery, rescued the accelerated senescence phenotype of npl3Δ cells. Thus, our study suggests that Npl3 plays an additional role in regulating cellular senescence outside of RNA:DNA hybrid resolution and co-transcriptional processing.

The caspase-activated DNase promotes cellular senescence.

Cellular senescence is a response to many stressful insults. DNA damage is a consistent feature of senescent cells, but in many cases its source remains unknown. Here, we identify the cellular endonuclease caspase-activated DNase (CAD) as a critical factor in the initiation of senescence. During apoptosis, CAD is activated by caspases and cleaves the genomic DNA of the dying cell. The CAD DNase is also activated by sub-lethal signals in the apoptotic pathway, causing DNA damage in the absence of cell death. We show that sub-lethal signals in the mitochondrial apoptotic pathway induce CAD-dependent senescence. Inducers of cellular senescence, such as oncogenic RAS, type-I interferon, and doxorubicin treatment, also depend on CAD presence for senescence induction. By directly activating CAD experimentally, we demonstrate that its activity is sufficient to induce senescence in human cells. We further investigate the contribution of CAD to senescence in vivo and find substantially reduced signs of senescence in organs of ageing CAD-deficient mice. Our results show that CAD-induced DNA damage in response to various stimuli is an essential contributor to cellular senescence.

Neuregulin 1 mitigated prolactin deficiency through enhancing TRPM8 signaling under the influence of melatonin in senescent pituitary lactotrophs.

The age-related alterations in pituitary function, including changes in prolactin (PRL) production contributes to the systemic susceptibility to age-related diseases. Our previous research has shown the involvement of Nrg1 in regulating the expression and secretion of PRL. However, the precise role of Nrg1 in mitigating the senescence of pituitary lactotrophs and the underlying mechanisms are yet to be comprehended. Here, data from the GEPIA database was used to evaluate the association between transient receptor potential cation channel subfamily M member 8 (TRPM8) and PRL in normal human pituitary tissues, followed by immunofluorescence verification using a human pituitary tissue microarray. TRPM8 levels showed a significant positive association with PRL expression in normal human pituitary tissues, and both TRPM8 and PRL levels declined during aging, suggesting that TRPM8 may regulate pituitary aging by affecting PRL production. It was also found that treatment with exogenous neuregulin 1 (Nrg1) markedly delayed the senescence of GH3 cells (rat lactotroph cell line) generated by D-galactose (D-gal). In addition, melatonin reduced the levels of senescence-related markers in senescent pituitary cells by promoting Nrg1 / ErbB4 signaling, stimulating PRL expression and secretion. Further investigation showed that Nrg1 attenuated senescence in pituitary cells by increasing TRPM8 expression. Downregulation of TRPM8 activation eliminated Nrg1-mediated amelioration of pituitary cell senescence. These findings demonstrate the critical function of Nrg1 / ErbB signaling in delaying pituitary lactotroph cell senescence and enhancing PRL production via promoting TRPM8 expression under the modulation of melatonin.

The Changes of Mitochondria during Aging and Regeneration.

Aging and regeneration are opposite cellular processes. Aging refers to progressive dysfunction in most cells and tissues, and regeneration refers to the replacement of damaged or dysfunctional cells or tissues with existing adult or somatic stem cells. Various studies have shown that aging is accompanied by decreased regenerative abilities, indicating a link between them. The performance of any cellular process needs to be supported by the energy that is majorly produced by mitochondria. Thus, mitochondria may be a link between aging and regeneration. It should be interesting to discuss how mitochondria behave during aging and regeneration. The changes of mitochondria in aging and regeneration discussed in this review can provide a timely and necessary study of the causal roles of mitochondrial homeostasis in longevity and health.