Biochemistry and Cell Biology最新文献

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.

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.

This study used a modified flapless (FLT) version of tannase from Lactobacillus plantarum, (LpTan) to explore the effects of "stacking" site mutations predicted by Protein Repair One Stop Shop (PROSS) to increase stability. Four different LpTan structural-state models (including apo, substrate- and product- bound as well as FLT) were comparatively applied, yielding 143 predicted mutations. Of these, eight mutations (including Q63T, A65D, A184Y, A257D, V276Y, T321G, G421D, and G439D (FLT numbering)) were selected to stack, based on conservation of the prediction across all four structural states. Combinatorial screening of the arising 256-member library yielded a selection of possible hits, of which four were further characterized. Variant P6H7 contained 7 of the 8 mutations (excluding V276Y) and showed the highest significant k_cat, 17% higher than FLT and 30% higher than LpTan, and a 4.5 °C increase in T_m . Variant P8E5 with 6 of 8 mutations (excluding A257D and G439D), yielded a 6.5 °C increase in T_m compared to FLT. The two other variants showed more moderate increases, albeit still greater than FLT or LpTan. Overall, the ability to design thermal stabilized versions of a tannase is emphasized. Putative mechanisms underlying the stabilization imparted by the highlighted variations are discussed.

Recruitment of faculty members in academic departments shapes the department for decades in research and teaching arenas. A diverse department is beneficial for all students as representation of underrepresented minority groups in the professoriate can inspire a greater diversity of students to pursue higher levels of education or research-focused careers. Increased diversity benefits research directly as diverse teams have been shown to have better ideas and outcomes. In 2020, our department had lower gender diversity than expected based on the pool of qualified personnel in Canada. Therefore, we altered our hiring process, primarily by redacting applications, for recruitment into entry-level tenure-track faculty positions. This resulted in the increased hiring of women (17% to 80%) with no substantial change in hiring of racially diverse individuals (50% to 40%). Overall, combined with retirements, the percentage of women faculty in the department went from 25% to 50% and the percentage of racialized faculty went from 38% to 44%. Thus, our intervention was successful in increasing the diversity of our department within a short timeframe. Our experience could provide other departments with a template for making substantive change, even in the absence of internal expertise in the area.

The hexosamine biosynthetic pathway (HBP) is upregulated in many cancer cell types leading to upregulation of post-translational modification of proteins by β-N-acetylglucosamine (O-GlcNAc), the product of HBP. However, our knowledge of the identity of proteins that undergo O-GlcNAcylation in cancer cells and consequently their roles is very limited. We investigated the O-GlcNAcylation of epidermal growth factor receptor (EGFR) and glucose transporter 1 (GLUT1) in T47D and MDA-MB-231 breast cancer cell models. We examined the effect of the loss of putative O-GlcNAcylation sites in EGFR and GLUT1 on cell-signaling pathways and their functional consequences on cell cycle progression and cell metabolism using fluorescence-activated cell sorting analysis and in vitro assays. EGFR and GLUT1 undergo O-GlcNAcylation in T47D and MDA-MB-231 breast cancer cells, which enhances their functions and prevents their intrinsic downregulation. This appears to involve an interplay between phosphorylation, O-GlcNAcylation, and ubiquitination in both proteins. Importantly, perturbing the putative O-GlcNAcylation sites in both proteins adversely affected their stability, functions, and metabolic status of breast cancer cells, including glucose uptake and lactate production. In conclusion, the reprogrammed metabolism in cancer cells extends beyond energy and macromolecule requirements and contributes to cell-signaling events that support the stability and function of cancer promoting proteins.

The XVIth International Conference on Lactoferrin, held in Rome in November 2023, showcased cutting-edge research on the multifunctional glycoprotein lactoferrin (Lf). Known for its broad antimicrobial, anti-inflammatory, and immunomodulatory properties, Lf continues to challenge the one-protein-one-function paradigm. Presentations highlighted its evolving therapeutic applications, including anti-biofilm strategies, modulation of immune responses, iron homeostasis, gut health, and cancer inhibition. Studies emphasized the importance of Lf source, iron saturation, and formulation, including recombinant and peptide derivatives. The collection underscores the expanding biomedical relevance of Lf and sets the stage for continued exploration at the upcoming XVIIth Conference in Mazatlán, Mexico.

Filamins are dimeric actin-binding protein that play a critical role in mechanical signaling. They contain a mechanosensory region (MSR) that naturally folds into a globular closed conformation. Under mechanical stress, the MSR unfolds into an open conformation, exposing binding sites for numerous proteins. Filamins are involved in diverse cellular functions, and their mechanical binding targets are highly context-dependent. In this study, we employed AlphaFold2 modelling for screening proteins that specifically recognize the open conformation of filamins. We focused on the Drosophila melanogaster filamin, Cheerio, and conducted a biased screen to identify mechanical binding proteins. We selected the top 132 hits from the initial screening for further characterization. All identified binding proteins specifically recognize the open conformation of the MSR and not the closed conformation. Interestingly, the binding regions of these proteins lack obvious sequence similarity. While some false positives were identified, they could be effectively filtered out based on the secondary structure formed at the binding interface. This study provides a framework for identifying specifically filamin interactions in mechanosignaling.

Recently, several antimicrobial peptides (AMPs), varying in length from 12 to 37 residues, have been shown to act as antibiofilm agents. Here, we report a study of 23 hexapeptides modeled after four different Trp- and Arg-rich AMPs, including the RRWQWR-NH₂ peptide, derived from bovine lactoferrin. They were tested against the pathogenic Gram-negative Pseudomonas aeruginosa PAO1 strain and a Gram-positive Staphylococcus aureus MRSA strain. Both strains were engineered to express the green fluorescent protein (GFP) protein, and fluorescence detection was used to measure the ability of the peptides to prevent biofilm formation (minimum biofilm inhibitory concentration (MBIC)) or to cause the breakdown of established biofilms (minimum biofilm eradication concentration (MBEC)). Similar antibiofilm activities were obtained with the standard crystal violet dye assay. Most Trp- and Arg-rich hexapeptides displayed a potent antibiofilm activity against the Gram-positive S. aureus MRSA strain. In particular, hexapeptides with 3 Arg and 3 Trp were very effective, especially when they contained the three Trp in sequence. Somewhat unexpectedly, the antimicrobial (MIC) values correlated with the MBIC and MBEC values, which has not been seen for several other AMP/antibiofilm peptides. Our results demonstrate that short Trp- and Arg-rich peptides merit further studies as antibiofilm agents that could be deployed to address part of the antimicrobial resistance problem.

Pediatric infections account for approximately one-third of all deaths in children under 5 years 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 in population under 18 years old. The primary outcomes were infection-associated outcomes: late onset sepsis (LOS), diarrhea, and upper respiratory infections (URIs). We also analyzed mortality among LOS studies. Of 1594 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 (odds ratio (OR): 0.60; 95% confidence interval (CI): 0.42-0.86), with fewer patients with diarrhea compared to placebo in children (OR: 0.56; 95% CI: 0.41-0.75), and no significant fewer patients with URI (OR: 0.61; 95% CI: 0.27-1.40). 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.

E2F transcription factor 8 (E2F8) is an important regulator of the cell cycle. In this study, we first assessed the expression of E2F8 in bladder cancer and examined its effects in the malignant phenotypes of bladder cancer cell lines. We found that E2F8 was upregulated in bladder cancer tissues, and the increased expression was positively associated with higher clinical stage. E2F8 knockdown suppressed bladder cancer cell proliferation, accompanied by the performance of G1 phase arrest and the upregulated Cyclin D1 protein expression. The migrative and invasive capability was reduced in E2F8-depleted bladder cancer cells. Cisplatin resistance is an important cause of bladder cancer relapse. E2F8 downregulation facilitated cisplatin-induced apoptosis of bladder cancer cells. MCM7 is regulated by E2F and has been shown to participate in bladder cancer. There was a positive correlation between E2F8 and MCM7 expression in bladder cancer. We confirmed that E2F8 bound to the promoter region of MCM7 and activated MCM7 transcription. MCM7 overexpression abrogated the suppressive effects of E2F8 knockdown on malignant phenotypes of bladder cancer cells. We also demonstrated that E2F8 knockdown suppressed bladder cancer progression in vivo. In conclusion, we verify that E2F8 functioned in bladder cancer, and might exert its function via MCM7.