Cell Death & Disease最新文献

Dysregulated mitochondrial fusion and fission has been implicated in the pathogenesis of numerous diseases. We have identified a novel function of the p53 family protein TAp73 in regulating mitochondrial dynamics. TAp73 regulates the expression of Optic Atrophy 1 (OPA1), a protein responsible for controlling mitochondrial fusion, cristae biogenesis and electron transport chain function. Disruption of this axis results in a fragmented mitochondrial network and an impaired capacity for energy production via oxidative phosphorylation. Owing to the role of OPA1 in modulating cytochrome c release, TAp73^-/- cells display an increased sensitivity to apoptotic cell death, e.g., via BH3-mimetics. We additionally show that the TAp73/OPA1 axis has functional relevance in the upper airway, where TAp73 expression is essential for multiciliated cell differentiation and function. Consistently, ciliated epithelial cells of Trp73^-/- (global p73 knock-out) mice display decreased expression of OPA1 and perturbations of the mitochondrial network, which may drive multiciliated cell loss. In support of this, Trp73 and OPA1 gene expression is decreased in chronic obstructive pulmonary disease (COPD) patients, a disease characterised by alterations in mitochondrial dynamics. We therefore highlight a potential mechanism involving the loss of p73 in COPD pathogenesis. Our findings also add to the growing body of evidence for growth-promoting roles of TAp73 isoforms.

Glioblastoma is one of the most common and aggressive primary brain tumors. The aberration of metabolism is the important character of GBM cells and is tightly related to the malignancy of GBM. We mainly verified the regulatory effects of KHDRBS1, SNORD51 and ZBED6 on pentose phosphate pathway and malignant biological behavior in glioblastoma cells, such as proliferation, migration and invasion. KHDRBS1 and SNORD51 were upregulated in GBM tissues and cells. But ZBED6 had opposite tendency in GBM tissues and cells. KHDRBS1 may improve the stability of SNORD51 by binding to SNORD51, thus elevating the expression of SNORD51. More importantly, SNORD51 can competitively bind to WDR33 with 3'UTR of ZBED6 pre-mRNA which can inhibit the 3' end processing of ZBED6 pre-mRNA, thereby inhibiting the expression of ZBED6 mRNA. ZBED6 inhibited the transcription of G6PD by binding to the promoter region of G6PD. Therefore, the KHDRBS1/SNORD51/ZBED6 pathway performs an important part in regulating the pentose phosphate pathway to influence malignant biological behavior of GBM cells, providing new insights and potential targets for the treatment of GBM.

Asthenoteratozoospermia is a major cause of male infertility. Thus far, the identified related genes can explain only a small share of asthenoteratozoospermia cases, suggesting the involvement of other genes. The transmembrane protein TMEM232 is highly expressed in mouse testes. In the present study, to determine its function of TMEM232 in testes, we constructed a Tmem232-null mouse model using CRISPR-Cas9 technology. Tmem232 knockout (KO) male mice was completely infertile, and their sperm were immotile, with morphological defects of the flagellum. Electron microscopy revealed an aberrant midpiece-principal junction and the loss of the fourth outer microtubule doublet in the sperm of Tmem232^-/- mice. Sperm cells presented an 8 + 2 conformation and an irregular arrangement of the mitochondrial sheath. Proteomic analysis revealed altered expression of proteins related to flagellar motility, sperm capacitation, the integrity and stability of sperm structure, especially an upregulated expression of multiple ribosome components in TMEM232-deficient spermatids. Additionally, TMEM232 was observed to be involved in autophagy by interacting with autophagy-related proteins, such as ATG14, to regulate ribosome homeostasis during spermiogenesis. These results suggest that TMEM232, as a potential scaffold protein involving in the correct assembly, distribution, and stability maintenance of certain functional complexes by recruiting key intracellular proteins, is essential for the formation of a highly structured flagellum and plays an important role in the autophagic elimination of cytosolic ribosomes to provide energy for sperm motility.

Enhancer of zeste homolog 2 (EZH2), a key protein implicated in various cancers including hepatocellular carcinoma (HCC), is recognized for its association with epigenetic dysregulation and pathogenesis. Despite clinical explorations into EZH2-targeting therapies, the mechanisms underlying its role in gene suppression in HCC have remained largely unexplored. Here, we integrate epigenomic and transcriptomic analyses to uncover the transcriptional landscape modulated by selective EZH2 inhibition in HCC. By reanalyzing transcriptomic data of HCC patients, we demonstrate that EZH2 overexpression correlates with poor patient survival. Treatment with the EZH2 inhibitor tazemetostat restored expression of genes involved in cysteine-methionine metabolism and lipid homeostasis, while suppressing angiogenesis and oxidative stress-related genes. Mechanistically, we demonstrate EZH2-mediated H3K27me3 enrichment at cis-regulatory elements of transsulfuration pathway genes, which is reversed upon inhibition, leading to increased chromatin accessibility. Among 16 EZH2-targeted candidate genes, BHMT and CDO1 were notably correlated with poor HCC prognosis. Tazemetostat treatment of HCC cells increased BHMT and CDO1 expression while reducing levels of ferroptosis markers FSP1, NFS1, and SLC7A11. Functionally, EZH2 inhibition dose-dependently reduced cell viability and increased lipid peroxidation in HCC cells. Our findings reveal a novel epigenetic mechanism controlling lipid peroxidation and ferroptosis susceptibility in HCC, providing a rationale for exploring EZH2-targeted therapies in this malignancy.

The liver regenerates after injury; however, prolonged injury can lead to chronic inflammation, fatty liver disease, fibrosis, and cancer. The mechanism involving the complex pathogenesis of the progression of liver injury to chronic liver disease remains unclear. In this study, we investigated the dynamics of gene expression associated with the progression of liver disease. We analyzed changes in gene expression over time in a mouse model of carbon tetrachloride (CCl₄)-induced fibrosis using high-throughput RNA sequencing. Prolonged CCl₄-induced liver injury increased the expression levels of genes associated with the unfolded protein response (UPR), which correlated with the duration of injury, with substantial, progressive upregulation of muscle, intestine, and stomach expression 1 (Mist1, bhlha15) in the mouse fibrosis model and other liver-damaged tissues. Knockdown of MIST1 in HepG2 cells decreased tribbles pseudokinase 3 (TRIB3) levels and increased apoptosis, consistent with the patterns detected in Mist1-knockout mice. MIST1 expression was confirmed in liver tissues from patients with metabolic dysfunction-associated steatohepatitis and alcoholic steatohepatitis (MASH) and correlated with disease progression. In conclusion, MIST1 is expressed in hepatocytes in response to damage, suggesting a new indicator of liver disease progression. Our results suggest that MIST1 plays a key role in the regulation of apoptosis and TRIB3 expression contributing to progressive liver disease after injury.

The function of PD-1/PD-L1 axis have been intensively studied for immune escape of various cancers. However, the underlying function of PD-L2 remains poorly understood. Here, we demonstrate that PD-L2 is majorly expressed in exosomes with surface localization by clear cell renal cell carcinoma (ccRCC) cells. Tumor cell-derived exosome PD-L2 (TDE-PD-L2) exhibits high expression compared with TDE-PD-L1 in various cancers. In the absence of adaptive immune, TDE-PD-L2 suppresses tumor growth and metastasis. Under immune competence condition, TDE-PD-L2 is hijacked by immune cells in a PD-1-dependent manner to systematically dampen function of T cells via the increased proportion of the regulatory T cells and the decreased proportion of cytotoxic CD8⁺ T cells in both tumor-infiltrating T cells and spleen. The effects of TDE-PD-L2 on tumor is restored by antibodies targeting PD-L2. Collectively, we demonstrate that PD-1/TDE-PD-L2 axis systematically suppresses T cell functions, representing a potentially therapeutic strategy for ccRCC treatment.

The TAp63α protein is highly expressed in primordial follicle oocytes, where it typically exists in an inactive dimeric form. Upon DNA damage, TAp63α undergoes hyperphosphorylation, transitioning from a dimeric to a tetrameric structure, which initiates oocyte apoptosis by upregulating pro-apoptotic gene. Our results demonstrate that cisplatin, an alkylating anti-cancer agent, predominantly produced the TAp63α dimer rather than the tetramer. We further observed that TAp63α protein accumulation occurred in primordial follicle oocytes following cisplatin treatment, and this accumulation was significantly reduced by cycloheximide, a protein synthesis inhibitor. These findings suggest that TAp63α accumulation is driven primarily by de novo protein synthesis in response to DNA damage. Notably, cycloheximide protected oocytes from cisplatin-induced apoptosis, as evidenced by reduced levels of both PUMA, a known pro-apoptotic target gene of TAp63α, and TAp63α itself. Additionally, TAp63α turnover appears to be regulated by ubiquitination and proteasome degradation, as evidenced by TAp63α accumulation without oocyte death when treated with PYR-41, a pharmacological inhibitor. However, when TAp63α was stabilized by PYR-41 and subsequently activated by cisplatin, oocyte death occurred, marked by increased γH2AX and Cleaved PARP. Moreover, the Casein kinase 1 inhibitor PF-670462 effectively blocked cisplatin-induced oocyte death, indicating that CK1-mediated phosphorylation is essential for TAp63α activation, even in the absence of tetramer formation. The ATR inhibitor BEZ235 prevented cisplatin-induced TAp63α accumulation, suggesting that TAp63α accumulation precedes its phosphorylation-driven activation. Collectively, our study reveals a novel mechanism of cisplatin-induced apoptosis in primordial follicle oocyte through TAp63α stabilization and accumulation, independent of tetramerization.

Intra-tumor immune infiltration plays a pivotal role in the interaction with tumor cells in hepatocellular carcinoma (HCC). However, its phenotype and related spatial structure remained elusive. To address these limitations, we conducted a comprehensive study combining spatial data (38,191 spots from eight samples) and single-cell data (56,022 cells from 20 samples). Our analysis revealed two distinct infiltration patterns: immune exclusion and immune activation. Plasma cells emerged as the primary cell type within intra-tumor immune clusters. Notably, we observed the co-location of CCL19+ fibroblasts with plasma cells, which secrete chemokines and promote T-cell activation and leukocyte migration. Conversely, in immune-exclusion samples, this co-location was primarily observed in the adjacent normal area. This co-localization correlated with T cell infiltration and the formation of tertiary lymphoid structures, validated by multiplex immunofluorescence conducted on twenty HCC samples. Both CCL19+ fibroblasts and plasma cells were associated with favorable survival outcomes. In an immunotherapy cohort, HCC patients who responded favorably exhibited higher infiltration of CCL19+ fibroblasts and plasma cells. Additionally, we observed the accumulation of DKK1+ tumor cells within the tumor area in immune-exclusion samples, particularly at the tumor boundary, which inhibited the infiltration of CCL19+ fibroblasts and plasma cells into the tumor area. Furthermore, in immune-exclusion samples, the SPP1 signaling pathway demonstrated the highest activity in communication between tumor and immune clusters, and CCL19-CCR7 played a pivotal role in the self-communication of immune clusters. This study elucidates immune exclusion and immune activation patterns in HCC and identifies relevant factors contributing to immune resistance.

RE-1 silencing transcription factor (REST) is a key repressor of neural genes. REST is upregulated under stress signals, aging and neurodegenerative diseases, but although it is upregulated, its function is lost in Alzheimer's Disease. However, why it becomes inactive remains unclear. Here, we show that the NAD-dependent deacetylase SIRT6 regulates REST expression, location and activity. In the absence of SIRT6, REST is overexpressed but mislocalized, leading to a partial loss of its activity and causing it to become toxic. SIRT6 deficiency abrogates REST and EZH2 interaction, perturbs the location of REST to the heterochromatin Lamin B ring, and leads to REST target gene overexpression. SIRT6 reintroduction or REST methyl-mimic K494M expression rescues this phenotype, while an acetyl-mimic mutant loses its function even in WT cells. Our studies define a novel regulatory switch where, depending on SIRT6 presence, the function of REST is regulated by post-translational modifications on K494 (Ac/me), affecting neuronal gene expression. In WT cells (left), REST functions as a repressor due to its methylation, which allows proper localization and interaction with EZH2. In SIRT6 KO cells (right), REST is overexpressed, but it is mislocalized and acetylated instead of methylated, impairing its interaction with EZH2. REST localizes in the cytoplasm in autophagosomes. The overall increase in REST without SIRT6 results in non-functional and toxic REST proteins. During aging, SIRT6 declines in the brain, while REST is upregulated to protect it. In pathological aging, where SIRT6 levels are very low, the increase in REST without SIRT6 results in non-functional and toxic REST.

Osteoporosis is a major degenerative metabolic bone disease that threatens the life and health of postmenopausal women. Owing to limitations in detection methods and prevention strategy awareness, the purpose of osteoporosis treatment is more to delay further deterioration rather than to fundamentally correct bone mass. We aimed to clarify the pathogenesis of postmenopausal osteoporosis and optimize treatment plans. Our experiments were based on previous findings that oxidative stress mediates bone metabolism imbalance after oestrogen deficiency. Through energy metabolism-targeted metabolomics, we revealed that purine metabolism disorder is the main mechanism involved in inducing oxidative damage in bone tissue, which was verified via the use of machine-learning data from human databases. Xanthine and xanthine oxidase were used to treat osteoblasts to construct a purine metabolism disorder model. The activity and differentiation ability of osteoblasts decreased after X/XO treatment. Transcriptomic sequencing indicated that autophagic flux damage was involved in purine metabolism-induced oxidative stress in osteoblasts. Additionally, we performed serum metabolomics combined with network pharmacology to determine the pharmacological mechanism of metformin in the treatment of postmenopausal osteoporosis. HPRT1 was the potential target filtered from the hub genes, and FoxO1 signalling was the key pathway mediating the effect of metformin in osteoblasts. We also revealed that SIRT3-mediated deacetylation promoted the nuclear localization of FoxO1 to increase the expression of HPRT1. HPRT1 upregulation promoted purine anabolism and prevented the accumulation of ROS caused by purine catabolism to reverse oxidative damage in osteoblasts. We propose that purine metabolism disorder-induced oxidative stress is important for the pathogenesis of postmenopausal osteoporosis. The therapeutic mechanism of metformin should be confirmed through subsequent drug optimization and development studies to improve bone health in postmenopausal women.