Heat shock proteins and cellular senescence in humans: A systematic review

CRISPR/Cas9-Mediated Knockout of BmGDAP2 in the Silkworm, Bombyx mori: Extended Lifespan and Altered Gene Expression Impacting Developmental Pathways

Ganglioside-induced differentiation-associated protein 2 (GDAP2) is a gene involved in hereditary cerebellar ataxia. At present, little is known about the function of GDAP2 in insects. In this study, BmGDAP2 was detected to be highly expressed in the head, epidermis, midgut, and anterior silk glands of silkworms. We generated a knockout mutant, BmGDAP2 (BmGDAP2KO), using the CRISPR/Cas9 system. Compared with that of the wild-type, the growth cycle of BmGDAP2KO larvae was significantly prolonged, while their body size was reduced. Furthermore, we found 149 differentially expressed genes (DEGs) between BmGDAP2KO and the wild-type, including 106 upregulated and 43 downregulated genes. GO annotation analysis indicated that BmGDAP2 primarily influences structural and molecular activities, as well as catalytic and binding functions. KEGG pathway analysis revealed that the differentially expressed genes were mainly enriched in pathways related to peroxidase activity, hormone synthesis, apoptosis, and longevity regulation. Further investigation focused on candidate genes related to these pathways. We found that the expression levels of MAD2L1, which can inhibit cell proliferation and promote apoptosis, and Aurka-b, which plays a crucial role in cell cycle regulation, were significantly reduced in BmGDAP2KO silkworms. These changes may interfere with the normal functions of cell division, leading to the prolonged developmental cycle observed in BmGDAP2KO larvae. Our findings demonstrate that knockout of BmGDAP2 significantly prolongs the life cycle of Bombyx mori by affecting genes related to autophagy, apoptosis, and hormone regulation.

Comparative analysis of transcriptomic profiles of mesenchymal stem cells at the onset of senescence and after exposure to acute exogenous oxidative stress

Cellular senescence can be triggered by a wide range of stress-inducing factors, including environmental and internal damaging events, such as oxidative stress. Moreover, stressed and senescent cells exhibit modifications in their transcriptional expression profile, but little is known regarding the common genes and pathways regulating these processes. Here, we analyzed the effects of long-term culture as well as exogenous acute oxidative stress on the transcriptional program of Wharton's jelly mesenchymal stem cells (WJ-MSCs). We demonstrate that, exposure to H2O2 compromised genomic stability and mitochondrial function in early passage WJ-MSCs, potentially initiating senescence to prevent cellular transformation. On the other hand, prolonged in vitro expansion of WJ-MSCs activated processes linked to integrins and extracellular matrix organization, possibly indicating the unfavorable consequences that senescence has on tissue integrity. Additionally, cells entering senescence and oxidative stressed young WJ-MSCs over-activated transcription factors related to permanent proliferative arrest and suppressed anti-senescence factors. Common differentially expressed genes in the late passage and H2O2-treated WJ-MSCs were implicated in DNA damage response and cell cycle arrest, which are known to trigger a senescent phenotype. Notably, the TP53INP1 gene emerged as a significantly upregulated gene in both late passage and H2O2-treated young WJ-MSCs, marking it as a potent senescence indicator. Silencing TP53INP1 mitigated the senescent phenotype, a role that appeared to be facilitated by autophagy regulation. Taken together, our results shed light on how transcriptomic changes govern MSCs' senescence program and identify key molecular drivers that could prove crucial for WJ-MSCs-based clinical applications.

Cellular Stress Responses and Associated Diseases: A Focus on Heat Shock Proteins

Cellular stress response is the response of the cell at molecular level in order to combat various environmental stressors / viral infections. These stressors can be either intra or extracellular. In the beginning of the insult cell tries to recoup from these adverse events by various mechanism like heat shock protein response, unfolded protein response, mitochondrial stress signaling, DNA damage response etc. However, if these stressors exceed the cellular capacity to coup with it, it leads to programmed cell death and senescence. Also, chronic stress and cortisol released in response to cellular stress decreases telomerase activity which is needed to replenish telomeres which are protective casing at the end of a strand of DNA. Too low telomeres lead to cell death or cell become pro-inflammatory leading to aging process and other health associated risks like cardiovascular diseases neurodegenerative diseases, autoimmune diseases, cancers etc.

Luteolin-mediated phosphoproteomic changes in chicken splenic lymphocytes: Unraveling the detoxification mechanisms against ammonia-induced stress

Long-term exposure to high ammonia concentrations could severely impact chicken health. On the other hand, luteolin has been shown to protect against ammonia poisoning. Although phosphorylation is critically involved in toxicity induction, the specific role of phosphorylated proteins in ammonia poisoning remains unclear. Herein, we constructed an in vitro model to study chicken ammonia poisoning and also analyzed the protective effects of luteolin. Specifically, a combined series of organic techniques such as protein extraction, enzyme digestion, modified peptide enrichment, Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) analysis, and bioinformatics analysis were employed for a quantitative omics study of phosphorylation modification in three groups of samples. Our findings revealed thousands of Differentially Expressed Proteins (DEPs). The differentially expressed modified proteins were subjected to GO classification, KEGG pathway analysis, cluster analysis, and protein interaction analysis, revealing the detoxification mechanism encompassed mitochondrial maintenance, signal transduction, transcriptional regulation, and cytoskeleton regulation. In the process, mitochondria and Golgi apparatus were the key organelles. Furthermore, the AKT1/FOXO signaling pathway and Heat Shock Proteins (HSPs) were the key core modifiers of the proteins. We hope that our findings will provide a theoretical basis and experimental support for future research on luteolin's detoxification mechanism against ammonia poisoning.

Cellular senescence in acute kidney injury: Target and opportunity

Acute kidney injury (AKI) is a common clinical disease with a high incidence and mortality rate. It typically arises from hemodynamic alterations, sepsis, contrast agents, and toxic drugs, instigating a series of events that culminate in tissue and renal damage. This sequence of processes often leads to acute renal impairment, prompting the initiation of a repair response. Cellular senescence is an irreversible arrest of the cell cycle. Studies have shown that renal cellular senescence is closely associated with AKI through several mechanisms, including the promotion of oxidative stress and inflammatory response, telomere shortening, and the down-regulation of klotho expression. Exploring the role of cellular senescence in AKI provides innovative therapeutic ideas for both the prevention and treatment of AKI. Furthermore, it has been observed that targeted removal of senescent cells in vivo can efficiently postpone senescence, resulting in an enhanced prognosis for diseases associated with senescence. This article explores the effects of common anti-senescence drugs senolytics and senostatic and lifestyle interventions on renal diseases, and mentions the rapid development of mesenchymal stem cells (MSCs). These studies have taken senescence-related research to a new level. Overall, this article comprehensively summarizes the studies on cellular senescence in AKI, aiming is to elucidate the relationship between cellular senescence and AKI, and explore treatment strategies to improve the prognosis of AKI.

Neuronal CBP-1 is required for enhanced body muscle proteostasis in response to reduced translation downstream of mTOR

Background

The ability to maintain muscle function decreases with age and loss of proteostatic function. Diet, drugs, and genetic interventions that restrict nutrients or nutrient signaling help preserve long-term muscle function and slow age-related decline. Previously, it was shown that attenuating protein synthesis downstream of the mechanistic target of rapamycin (mTOR) gradually increases expression of heat shock response (HSR) genes in a manner that correlates with increased resilience to protein unfolding stress. Here, we investigate the role of specific tissues in mediating the cytoprotective effects of low translation.

Methods

This study uses genetic tools (transgenic C. elegans , RNA interference and gene expression analysis) as well as physiological assays (survival and paralysis assays) in order to better understand how specific tissues contribute to adaptive changes involving cellular cross-talk that enhance proteostasis under low translation conditions.

Results

We use the C. elegans system to show that lowering translation in neurons or the germline increases heat shock gene expression and survival under conditions of heat stress. In addition, we find that low translation in these tissues protects motility in a body muscle-specific model of proteotoxicity that results in paralysis. Low translation in neurons or germline also results in increased expression of certain muscle regulatory and structural genes, reversing reduced expression normally observed with aging in C. elegans . Enhanced resilience to protein unfolding stress requires neuronal expression of cbp-1 .

Conclusion

Low translation in either neurons or the germline orchestrate protective adaptation in other tissues, including body muscle.

Insulin and aging - a disappointing relationship

Experimental studies in animal models of aging such as nematodes, fruit flies or mice have observed that decreased levels of insulin or insulin signaling promotes longevity. In humans, hyperinsulinemia and concomitant insulin resistance are associated with an elevated risk of age-related diseases suggestive of a shortened healthspan. Age-related disorders include neurodegenerative diseases, hypertension, cardiovascular disease, and type 2 diabetes. High ambient insulin concentrations promote increased lipogenesis and fat storage, heightened protein synthesis and accumulation of non-functional polypeptides due to limited turnover capacity. Moreover, there is impaired autophagy activity, and less endothelial NO synthase activity. These changes are associated with mitochondrial dysfunction and oxidative stress. The cellular stress induced by anabolic activity of insulin initiates an adaptive response aiming at maintaining homeostasis, characterized by activation of the transcription factor Nrf2, of AMP activated kinase, and an unfolded protein response. This protective response is more potent in the long-lived human species than in short-lived models of aging research resulting in a stronger pro-aging impact of insulin in nematodes and fruit flies. In humans, resistance to insulin-induced cell stress decreases with age, because of an increase of insulin and insulin resistance levels but less Nrf2 activation. These detrimental changes might be contained by adopting a lifestyle that promotes low insulin/insulin resistance levels and enhances an adaptive response to cellular stress, as observed with dietary restriction or exercise.

Meta-analysis of senescent cell secretomes to identify common and specific features of the different senescent phenotypes: a tool for developing new senotherapeutics

DNA damage resulting from genotoxic injury can initiate cellular senescence, a state characterized by alterations in cellular metabolism, lysosomal activity, and the secretion of factors collectively known as the senescence-associated secretory phenotype (SASP). Senescence can have beneficial effects on our bodies, such as anti-cancer properties, wound healing, and tissue development, which are attributed to the SASP produced by senescent cells in their intermediate stages. However, senescence can also promote cancer and aging, primarily due to the pro-inflammatory activity of SASP.Studying senescence is complex due to various factors involved. Genotoxic stimuli cause random damage to cellular macromolecules, leading to variations in the senescent phenotype from cell to cell, despite a shared program. Furthermore, senescence is a dynamic process that cannot be analyzed as a static endpoint, adding further complexity.Investigating SASP is particularly intriguing as it reveals how a senescence process triggered in a few cells can spread to many others, resulting in either positive or negative consequences for health. In our study, we conducted a meta-analysis of the protein content of SASP obtained from different research groups, including our own. We categorized the collected omic data based on: i) cell type, ii) harmful agent, and iii) senescence stage (early and late senescence).By employing Gene Ontology and Network analysis on the omic data, we identified common and specific features of different senescent phenotypes. This research has the potential to pave the way for the development of new senotherapeutic drugs aimed at combating the negative consequences associated with the senescence process. Video Abstract.