Biochemistry and Cell Biology最新文献

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.

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.

Galanthamine, an alkaloid derived from the Amaryllidaceae family, serves as an acetylcholinesterase inhibitor. Due to its central cholinergic properties, this compound is being actively studied as a potential treatment for Alzheimer's disease. However, the broader scope of its biological effects remains poorly understood. In this study, we explored the therapeutic potential of galanthamine in promoting neuronal differentiation and enhancing neurite outgrowth in neural stem and progenitor cells (NSPCs). Our detailed analysis demonstrated notable changes in neuronal morphology and complexity during maturation following galanthamine exposure. Notably, the compound significantly increased the proportion of neurons with multiple neurites, indicating its ability to stimulate neurite formation and foster the development of complex neuronal networks. Furthermore, galanthamine treatment led to a marked rise in the number of mature-appearing neurons, distinguished by elongated and intricate dendrites, highlighting its potential to enhance neural plasticity and repair mechanisms. Importantly, we also identified that galanthamine facilitates neuronal differentiation in NSPCs by up-regulating the insulin-like growth factor 2 signaling pathway. Collectively, these findings provide valuable insights into galanthamine's role in Alzheimer's disease and emphasize its promise as a therapeutic agent for this neurodegenerative disorder.

Chromatin remodeling plays a crucial role in gene expression. Chromatin architecture is governed by the interaction of a variety of proteins and transcription factors, including histones and non-histone chromatin-binding factors. Non-histone proteins, such as high mobility group-associated proteins High Mobility Group A (HMGA), are key players in this process. They do not have transcriptional activity per se but comprise flexible intrinsically disordered proteins (IDP) that interact with nucleosomes to change the compaction of chromatin at enhancers and promoters, thereby modulating the process of transcription. HMGA proteins have attained significant attention for their role in the regulation of gene expression during development, cell differentiation and in cellular senescence. Their molecular interactions are controlled by posttranslational modifications which determine nucleoprotein complex formation and function. This review highlights the role of HMGA proteins in nuclear organization, at telomeres and centromere regions and in senescence-associated heterochromatin foci and links these spatiotemporal chromatin architectural functions to the molecular domain structure of HMGA proteins in fine-tuning dynamic chromatin states.

Recently, proteomics analyses using databases of unannotated ORFs revealed that ubiquitin (Ub) variants can be encoded and expressed from pseudogenes. One such pseudogene, UBBP4, produces Ub^KEKS, which contains four substitutions (Q2K, K33E, Q49K, and N60S) relative to canonical Ub. Unlike Ub, Ub^KEKS does not promote proteasomal degradation through K48 linkages and instead modifies a distinct set of proteins. To elucidate the structural basis of this divergence, we solved the NMR solution structure of Ub^KEKS and characterized its backbone dynamics by 15N-relaxation. While Ub^KEKS retains the overall helix-grip fold, we observed significant rearrangements and amplified motions in residues governing the Ub pincer mode, a conformational switch that determines whether UIMs engage the canonical I44 interface or the α1-β3 edge. Specifically, Q2K and K33E cooperate to enhance motions on both fast (ps-ns) and slow (µs-ms) timescales within α1, the β1-β2 loop, and β5-regions central to pincer mode regulation. In addition, Q49K, adjacent to I44, perturbs UIM recognition and likely interferes with K48 chain formation and binding to the proteasomal receptor S5a. Collectively, our findings identify structural and dynamical determinants that explain Ub^KEKS's distinct substrate profile and inability to target proteins for degradation.

The most common medical therapy for endometriosis suppresses ovulation, which is a barrier for patients planning pregnancy. To address this issue, we focused on the cell proliferation-suppressing effects of lactoferrin, which reportedly in various malignant tumours. Despite being a benign disease, endometriotic cells have similar characteristics to malignant tumours, which may be involved in its onset and progression. Endometriotic and endometrial stromal cells were obtained from patients with endometriosis. After culture with 1 mg/mL of bovine lactoferrin, cell proliferation was significantly suppressed in endometriotic stromal cells compared to controls, but this remained unchanged in endometrial stromal cells. Bovine lactoferrin also significantly increased the number of endometriotic stromal cells in the G0/G1 phase and significantly decreased those in the S phase, and suppressed the protein expression of phosphorylated-AKT, phosphorylated-mTOR, phosphorylated-S6K, and cyclin D1. Bovine lactoferrin inhibits the transition from the G1 to the S phase by suppressing the PI3K/Akt/mTOR pathway and reducing the synthesis of cyclin D1, thereby arresting the cell cycle at the G1 phase. Bovine lactoferrin suppressed the proliferation of endometriotic stromal cells without suppressing the proliferation of endometrial stromal cells. Lactoferrin, which allows for pregnancy and lactation during administration, has potential as a novel therapeutic candidate for endometriosis.

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 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.