Cellular & Molecular Biology Letters最新文献

Colorectal cancer (CRC) ranks among the most common malignant cancers of the digestive system, and its initiation and progression are closely related to both genetic and epigenetic mechanisms. Three major forms of modifications, viz. DNA methylation, RNA m6A methylation, and histone methylation, play important roles in regulating gene expression at various stages of transcription and translation. These methylation processes are dynamic and reversible, relying on the functions of methyltransferases, demethylases, and methylation-binding proteins. Extensive studies have shown that DNA, RNA m6A, and histone methylation significantly impact multiple pathological and physiological processes in CRC, including carcinogenesis, recurrence, metastasis, resistance to both radiotherapy and chemotherapy, as well as immune regulation. Advances in high-throughput sequencing and laboratory techniques have facilitated the identification of methylation regulation enzymes with aberrant expression at the DNA, RNA, and protein levels, revealing their clinical potential for early diagnosis and treatment of CRC. The upstream regulatory mechanisms controlling these methylation regulation enzymes are crucial for understanding alterations in methylation patterns. Current evidence identifies several key mechanisms, including posttranslational modifications, epigenetic regulation, and genetic alterations, which collectively influence the expression, activity, and stability of methyltransferases, demethylases, and binding proteins. These mechanisms thereby modulate the dynamic methylation landscape across various biological contexts. Furthermore, the complex crosstalk among DNA, RNA m6A, and histone methylation is increasingly being elucidated, highlighting a need for further investigation in CRC. In this review, we systematically summarize the molecular mechanisms, clinical applications, and crosstalk involving DNA methylation, RNA m6A methylation, and histone methylation, along with their related enzymes in the development of CRC. This review aims to provide new insights and directions that underscore the significant role of epigenetic methylation modifications and their associated enzymes in CRC.

Background: Ovarian aging-induced decline in oocyte quality has been a main issue in women of advanced maternal age. However, the potential mechanism remains elusive, and there are no effective strategies to ameliorate aged oocyte quality. The lipid metabolism of oocytes has drawn great attention, but the intrinsic regulation of oocyte quality by metabolites, metabolic enzymes, and intracellular mediators is less well-characterized.

Methods: Targeted lipidomics was employed to detect the neutral lipids in oocytes during maturation. We used 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY 493/503) and Filipin to stain cholesteryl ester and free cholesterol, respectively. The Cholesterol/Cholesteryl Ester Quantification Assay kit was used further to quantify cholesterol-related metabolites. Western blotting was performed to evaluate acyl-coenzyme A: cholesterol acyltransferase 1/2 (ACAT1/2) expression. Immunofluorescence and quantitative real-time polymerase chain reaction (qRT-PCR) were conducted to validate the knockdown efficiency of ACAT1. Avasimibe treatment and ACAT1 small interfering RNA (siRNA) microinjection were performed to investigate the effect of impaired cholesterol-cholesteryl ester metabolism on oocyte quality. Single-oocyte RNA sequencing was conducted to explore the mechanism. Mitochondrial membrane potential (MMP), adenosine triphosphate (ATP) production, reactive oxygen species (ROS), and mitochondrial autophagosomes were detected to evaluate mitochondrial function and mitophagy.

Results: There is a profound increase in the conversion of cholesterol to cholesteryl ester in oocytes during maturation, which depends on ACAT1. Conversely, disturbing the homeostasis of cholesterol-cholesteryl ester metabolism by manipulating ACAT1 impairs oocyte quality, primarily manifested as decreased polar body extrusion (PBE), increased meiotic defects, and abnormal early embryonic development. Mechanistically, the impaired conversion of cholesterol to cholesteryl ester reduces oocyte mitophagy, leading to mitochondrial dysfunction, including reduced MMP and ATP production, and excessive accumulation of ROS. Notably, we also reveal that this metabolic homeostasis is impaired in aged oocytes, accompanied by decreased ACAT1 levels. Moreover, cholesteryl ester supplementation via cholesterol conjugated to methyl-β-cyclodextrin (CCM) can effectively ameliorate aged oocyte quality by enhancing mitophagy.

Conclusions: This study reveals the mechanism by which cholesterol-cholesteryl ester metabolism regulates oocyte quality and thus participates in the process of oocyte aging by influencing mitophagy and mitochondrial function.

Background: Obesity is an important risk factor for osteoarthritis (OA), but the mechanisms associated with OA progression are still not fully understood. The aim of this study was to investigate the role of cyclin-dependent kinase 5 (CDK5) in regulating the peroxisome proliferator-activated receptor gamma (PPARγ)/nuclear factor-κB (NF-κB) signaling pathway and its effect on obesity-related OA.

Methods: By analyzing tissue samples from obese and nonobese patients with OA in conjunction with a high-fat diet (HFD)-induced obese mouse model of OA, we investigated the expression level of CDK5 and its effects on inflammation and apoptosis. The role of CDK5 in macrophage polarization and chondrocyte apoptosis was further explored by gene knockdown and pharmacological intervention.

Results: CDK5 levels were found to be significantly elevated in obese patients with OA, promoting M1 macrophage infiltration and chondrocyte apoptosis. In the model, CDK5 knockdown attenuated cartilage damage and inhibited PPARγ phosphorylation and NF-κB signaling. In vitro experiments showed that overexpression of CDK5 facilitated M1 macrophage polarization and chondrocyte apoptosis, and PPARγ agonists reversed these effects. Mechanically, CDK5 binds to PPARγ to regulate the NF-κB signaling pathway.

Conclusion: CDK5 promotes the progression of obesity-associated OA through the PPARγ/NF-κB pathway and is a potential therapeutic target in OA, especially in obese patients.

Background: Radiotherapy for malignant tumor treatment and irradiation (IR)-related diagnosis damage lymphocytes, which inevitably suppresses immunity and leads to unwanted clinical outcomes. However, a few agents have been approved by the Food and Drug Administration (FDA) to alleviate IR-induced injury. Here, the radioprotective effect and underlying mechanism of a new steroidal compound optimized from estradiol (E0703) were investigated.

Methods: Mice were exposed to γ-ray IR to establish an in vivo model of radiation injury, and human peripheral blood B lymphocytes (AHH-1) were employed to investigate injury in lymphocytes. Protein level changes in cell and tissue samples were detected by western blot and immunofluorescence. DNA damage was assessed by the comet assay and γH2AX staining. RNA sequencing was used to screen the critical genes mediating the radioprotective effect of E0703. To determine the direct target of E0703, cellular thermal shift (CETSA), drug affinity responsive target stability (DARTS), molecular docking, and surface plasmon resonance (SPR) assays were adopted. GLI3 transactivation by estrogen receptor β (ERβ) was determined by the chromatin immunoprecipitation (ChIP) assay, while protein interactions were detected by coimmunoprecipitation (Co-IP). IP products were subjected to label-free proteomics assay to screen GLI3 conjugates.

Results: E0703 significantly improved survival and tissue injury in mice exposed to IR damage. In lymphocytes, IR-induced DNA damage was ameliorated with E0703 in an ataxia-telangiectasia mutated protein (ATM)-checkpoint kinase 2 (CHK2)-dependent manner. ERβ but not ERα was a direct target of E0703, wherein ERβ enhancement on the promoter region of GLI3 triggered by E0703 could sustain its protein expression. The interaction between GLI3 and eIF4G1 favored by E0703 was critical for the formation of the eIF4F translation-initiation complex. eIF4F assembly was indispensable for the stimulation of ATM-CHK2 signaling involved in DNA damage repair.

Conclusions: E0703 alleviated IR-induced DNA damage in lymphocytes by selectively targeting ERβ. The formation of the eIF4F complex in a GLI3-dependent manner was critical for ATM-CHK2 activation triggered by E0703. Our study provides an alternative countermeasure to alleviate IR-induced lymphopenia in individuals undergoing radiotherapy or IR-related diagnosis.

The human Y chromosome (ChrY), which confers male sex determination, contains a relatively small number of protein-coding genes compared to other chromosomes; consequently, its functional impact on adult physiology was once severely unappreciated. While the repetitive structure of the ChrY once impeded sequencing, technological advances have now made it possible to identify its contents. Despite the historical view of ChrY as a virtual wasteland, we now know that it encodes a variety of genes which are hugely consequential to both human health and disease. The extreme downregulation of ChrY gene expression, resulting from partial or total loss of ChrY (LOY), is a common characteristic observed in various disease states in men, including cardiovascular, neurodegenerative, immunological health issues, and ,most notably, cancer. Additionally, mosaic LOY (mLOY) is sometimes found in primary cancerous tissues and is associated with poorer clinical outcome. Although, the reasons for these associations were once elusive, they are now understood to be linked to the activity of several ChrY genes, as well as the pleiotropic effects of their loss. In this review, we critically analyze contemporary and historic scientific literature which evaluate the clinical LOY trends seen in male exclusive/predominant cancers as well as explore the now identified mechanisms of ChrY alteration in cancer initiation, progression, and metastasis. Moreover, we discuss recent research studies which have uncovered novel mechanisms through which LOY may induce the physiological and molecular changes in the tumor microenvironment (TME) associated with malignant transformation and the evasion of innate immunity. Interestingly, the TME formed by malignant cells with LOY appears to contribute to early T cell exhaustion in infiltrating immune cells and consequent compromised tumor clearance; a phenomenon which has been profusely observed in patient samples. Furthermore, we describe the tumor-suppressive activities of the ChrY demonstrated in previous studies, as well as its newly identified roles in cancer immunology.