Biochemistry and Cell Biology最新文献

The chromatin remodeler SRCAP plays a critical role in depositing the histone variant H2A.Z, which is essential for transcriptional regulation, chromatin accessibility, and neurodevelopmental processes. Despite its known importance, the mechanisms by which SRCAP regulates H2A.Z dynamics during neuronal differentiation remain poorly understood. Here, we investigated the impact of Srcap knockdown on H2A.Z incorporation and transcriptional regulation in N2A cells. Chromatin immunoprecipitation (ChIP) revealed reduced H2A.Z occupancy at activity-dependent and neurodevelopmental genes upon Srcap knockdown, confirming Srcap's role in H2A.Z deposition. Interestingly, CBP recruitment and global histone H3 acetylation were unaffected by Srcap knockdown at steady-state conditions, suggesting an H2A.Z-specific function of Srcap. We also observed that retinoic acid-induced neuronal differentiation leads to dynamic changes in H2A.Z levels at developmental loci, which are disrupted in Srcap-deficient cells. Gene expression analysis revealed altered expression of neurodevelopmental genes in the absence of Srcap, correlating with reduced H2A.Z occupancy. Together, these findings demonstrate that Srcap is essential for regulating H2A.Z dynamics and gene expression during neuronal differentiation, offering new insights into its role in chromatin remodelling and its potential involvement in neurodevelopmental disorders.

Estrogen (E2) regulates the differentiation and proliferation of mammary progenitor cells by modulating the transcription of multiple genes. One of the genes that is downregulated by E2 is SOX2, a transcription factor associated with stem and progenitor cells that is overexpressed during breast tumourigenesis. To elucidate the mechanisms underlying E2-mediated SOX2 repression, we investigated epigenome and transcriptome changes following short- and long-term E2 exposure in breast cancer cells. We found that short-term E2 exposure reduces chromatin accessibility at the downstream SOX2 SRR134 enhancer, decreasing SOX2 expression. In contrast, long-term E2 exposure completely represses SOX2 transcription while maintaining accessibility at the SRR124-134 enhancer cluster, keeping it poised for reactivation. This repression was accompanied by widespread epigenome and transcriptome changes associated with commitment towards a more differentiated and less invasive luminal phenotype. Finally, we identified a role for the transcription factor NFIB in this process, suggesting it collaborates with the estrogen receptor to mediate SOX2 repression and genome-wide epigenome accessibility changes.

WD repeat domain 4 (WDR4) has been reported to promote tumor metastasis in various cancers. However, its precise function in colorectal cancer (CRC) have not been reported yet. Herein, the expression pattern of WDR4 in CRC were determined by analyzing Gene Expression Omnibus datasets (GSE110225, GSE127069, GSE156355, and GSE184093) and GEPIA online dataset. In vitro and in vivo experiments, including CCK-8, colony formation, flow cytometry, wound healing, transwell assays, and xenograft mouse models, were used to investigate the role of WDR4 in CRC. Firstly, data from Kaplan-Meier database showed that high expression of WDR4 was associated with the poor prognosis of CRC patients. Then, upregulation of WDR4 was confirmed in clinical CRC tissues. in vitro functional experiments suggested that overexpression of WDR4 promoted cell proliferation, migration and invasion, while knockdown of WDR4 has the opposite effects. Also, the oncogenic role of WDR4 was also verified in in vivo experiments. CO-IP-LC/MS analysis uncovered that GSK3β is the central protein that binds to WDR4. Mechanistically, WDR4 activated the β-catenin pathway by promoting GSK3β phosphorylation. This study demonstrates that WDR4 promotes CRC progression through activating GSK3β/β-catenin pathway, indicating that WDR4 might be a potential therapeutic target for CRC treatment.

Pediatric infections account for approximately one-third of all deaths in children under 5 globally. Lactoferrin (LF) supplementation has the potential to reduce infection-related morbidity due to its antimicrobial, anti-inflammatory and immunoregulatory properties. We conducted a systematic review and meta-analysis of oral LF supplementation randomized controlled trials (RCT) in population under 18 years old. The primary outcomes were infection-associated outcomes: late onset sepsis (LOS), diarrhea, and upper respiratory infections (URI). We also analyzed mortality among LOS studies. Of 1,594 citations identified, 25 studies met eligibility criteria, including 10 studies of LOS, 14 of diarrhea and 8 of URI. LF supplementation was associated with fewer patients with culture-proven or probable neonatal LOS compared to placebo (OR: 0.60; 95% CI: 0.42 to 0.86), with fewer patients with diarrhea compared to placebo in children (OR: 0.56; 95% CI: 0.41 to 0.75), and no significant fewer patients with URI (OR: 0.61; 95% CI: 0.27 to 1.40). Before LF can be used as a public health intervention, it is necessary to refine some aspects of the design of future trials. Ideally these trials should be conducted in countries with the highest burden of infections, where the potential benefit is expected to have the largest impact.

DFAT cells represent an attractive source of stem cells in tissue engineering and in the potential treatment of several clinical conditions. Our objective was to determine whether DFAT cells originate from mature adipocytes and address whether contamination from the stromal vascular fraction (SVF) could be as a source for these cells. A murine adiponectin-creERT;mT/mG model was used with the excision of the cassette induced by tamoxifen injection for the cells expressing adiponectin (adipoq). This model allows distinguishing of mature adipocytes (green fluorescence) from other SVF cell types (red fluorescence) based on the fluorescent protein expressed. Mature adipocytes and SVF cells were isolated from adipose tissues by collagenase digestion. Ceiling cultures were imaged by time-lapse microscopy. Confocal microscopy was used to follow cells over 21 days. Time-lapse microscopy experiments showed liposecretion occurring in mature adipocytes displaying green fluorescence. Confocal imaging allowed the identification of a heterogeneous cell population expressing green but also red fluorescence after 21 days of culture. Asymmetrical division of mature adipocytes was not observed. In conclusion, liposecretion of mature adipocytes is a phenomenon that can be observed in vitro and DFAT cells do originate from mature adipocytes. However, the population of DFAT cells is heterogenous.

This study aims to explore the role of 1-deoxynojirimycin (DNJ) in high glucose-induced β-cells and to further explore the molecular mechanism of DNJ effect on β-cells through network pharmacology. In the study, high glucose treatment of mouse INS-1 cells inhibited cell proliferation and insulin secretion, decreased the expression of Bcl-2 protein and Ins1 and Ins2 genes, promoted apoptosis, and increased cleaved caspase-3 and cleaved caspase-9 expression levels as well as intracellular reactive oxygen species production. DNJ treatment significantly restored the dysfunction of INS-1 cells induced by high glucose, and DNJ showed no toxicity to normal INS-1 cells. Silencing CEBPA promoted, while overexpression of CEBPA relieved the dysfunction of pancreatic β-cells induced by high glucose. DNJ treatment partially restored the pancreatic β-cell dysfunction caused by silencing CEBPA. In conclusion, DNJ can inhibit high glucose-induced pancreatic β-cell dysfunction by promoting the expression of CEBPA.

TRIM3 is widely recognized as a tumor suppressor gene. However, its precise role in cervical squamous cell carcinoma (CESC) remains elusive. Here, we observed a significant decrease in the expression of TRIM3 in CESC cells. Overexpression of TRIM3 suppresses cell proliferation and clonal formation. Through the establishment of cisplatin (cDDP)-resistant CESC cell lines, we discovered that the expression of TRIM3 was further downregulated in cDDP-resistant cells, while overexpression of TRIM3 enhanced cellular sensitivity to cDDP. Mechanistic investigations revealed that TRIM3 directly interacts with GRP78, a crucial protein involved in endoplasmic reticulum stress (ERS) pathway, promoting its ubiquitination degradation. Under cDDP treatment, the overexpression of TRIM3 in cDDP-resistant cells suppressed cell proliferation and downregulated the expression of drug-resistant genes, while simultaneously enhancing the activation of apoptosis signaling pathways. However, co-expression of TRIM3 and GRP78 restored cellular sensitivity to cDDP back to normal levels. Consequently, overexpressing TRIM3 in drug-resistant cells facilitates PERK activation and subsequent induction of apoptosis through inhibition of GRP78, ultimately suppressing drug resistance and inducing apoptosis in CESC cells. In conclution, our study suggests that the TRIM3/GRP78 axis regulates cDDP resistance in CESC cells by modulating the downstream apoptotic pathway of ERS.

Transcription factors (TFs) are specialized proteins that bind DNA in a sequence-specific manner and modulate RNA polymerase II (Pol II) in multiple steps of the transcription process. Phase separation is a spontaneous or driven process that can form membrane-less organelles called condensates. By creating different liquid phases at active transcription sites, the formation of transcription condensates can reduce the water content of the condensate and lower the dielectric constant in biological systems, which in turn alters the structure and function of proteins and nucleic acids in the condensate. In RNA Pol II transcription, phase separation formation shortens the time at which TFs bind to target DNA sites and promotes transcriptional bursting. RNA Pol II transcription is engaged in developing several diseases, such as cardiovascular disease, by regulating different TFs and mediating the occurrence of phase separation. This review aims to summarize the advances in the molecular mechanisms of RNA Pol II transcriptional regulation, in particular the effect of TFs and phase separation. The role of RNA Pol II transcriptional regulation in cardiovascular disease will be elucidated, providing potential therapeutic targets for the management and treatment of cardiovascular disease.

G protein-coupled receptor (GPCR) signaling regulates a wide range of pathophysiological cell functions via G protein α and βγ subunits. Small molecules targeting the subunits of Gα and Gβγ have been developed as cancer therapeutics. We have previously reported that transforming growth factor-α (TGF-α) induces the migration of human hepatocellular carcinoma (HCC) HuH7 cells through the activation of AKT, p38 mitogen-activated protein kinase (MAPK), Rho-kinase, and c-Jun N-terminal kinase (JNK). This study aims to determine whether Gβγ subunits regulate the TGF-α-induced migration of HCC HuH7 cells using gallein, a Gβγ subunits inhibitor. The Janus family of tyrosine kinase/signal transducer and activator of transcription 3 (STAT3) signaling pathway was also involved in the regulation of the migration. Gallein significantly reduced the TGF-α-induced cell migration. In contrast, fluorescein, a gallein-related compound that has no effect on Gβγ subunits, failed to affect the cell migration. Gallein suppressed the TGF-α-stimulated phosphorylation of JNK without affecting the phosphorylation of epidermal growth factor receptor, AKT, p38 MAPK, target protein of Rho-kinase, and STAT3. Conversely, fluorescein did not attenuate the phosphorylation of JNK. These results strongly suggest that Gβγ subunits act as positive regulators in TGF-α-induced migration of HCC cells via the JNK signaling pathway.