Biochemistry and Cell Biology最新文献

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.

Cadherin-related family member 5 (CDHR5) is an adhesion molecule that is highly enriched in the microvilli found on the surface of transporting epithelial cells of the gut and kidney. CDHR5 localizes to the distal tips of these microvilli as part of an adhesion complex that drives assembly of microvilli into a cohesive apical brush border, a hallmark feature of polarized transporting epithelial cells. Loss of CDHR5 correlates with poor prognosis of colon cancer patients, while forced over-expression of CDHR5 in colorectal cancer cell lines blocks their ability to form tumors in mice. Despite acting as an apparent tumor suppressor, how CDHR5 targets to the apical domain of transporting epithelial cells to exert its tumor suppressor effects is poorly understood. Here, we show that CDHR5 is expressed as three dominant splice isoforms in intestinal epithelial cells that differ only in the presence and composition of a membrane-proximal extracellular mucin-like domain. When present in the CDHR5 ectodomain, this mucin-like domain restricted targeting of the cadherin to apical microvilli. Importantly, we show that this restriction could be bypassed through apparent hetero-oligomer formation between the splice isoforms that have the mucin-like domain and the isoform that does not.

Parkinson's disease (PD) is one of the most commonly affecting neurodegenerative disorder prevalent in our society. The inherited autosomal recessive PD/parkinsonism occurs due to mutations in six genes including, the gene for PTEN (phosphatase and tensin homologue)-induced putative kinase1 (PINK1). The pathophysiology and development of disorders associated with the mitochondria occur simultaneously with the dysregulation of PINK1. The activation/regulation of PINK1 through autophagy regulators can reduce PD condition. This study focused on exploring the possibility of 2062 phytochemicals as autophagy regulators. In silico docking and simulation studies are performed to identify their binding with the PINK1. Our studies highlight the phytochemicals like Proanthocyanidin A-6, Withanolide Q, and pseudo-ginsenoside F11 that showed higher binding energy and stable interactions during the course of simulation. This study opens avenues for testing these compounds as positive modulators of PINK1 kinase activity using in vitro and in vivo methods and use of these compounds as phytotherapeutic for the treatment of PD.

Immune checkpoint inhibitors (ICIs)-related myocarditis, a severe complication characterized by elevated cardiac troponin I, poses significant clinical challenges in distinguishing it from acute myocardial infarction (AMI). Our study aimed to identify plasma protein biomarkers that differentiate ICIs-myocarditis from AMI. Plasma samples from 5 ICIs-myocarditis patients (with paired baseline and diagnosis samples) and 5 angiography-confirmed AMI patients, matched for age, gender, smoking history, and pre-existing heart disease, were analyzed using label-free liquid chromatography-mass spectrometry proteomics. A total of 1521 plasma proteins were identified, with 1325 quantifiable. Proteomic profiling revealed differentially expressed proteins (DEPs) in ICIs-myocarditis associated with myocardial contraction, proteasome activity, NF-κB signaling, immunoregulation, and amino acid metabolism. Through validation in animal models of ICIs-myocarditis and AMI, two plasma proteins-MYOM3 (myomesin 3) and galectin-1 (LGALS1)-were identified as potential biomarkers linked to the onset of ICIs-related myocarditis. Further validation using expanded clinical cohorts confirmed their differential expression. These findings highlight MYOM3 and galectin-1 as promising biomarkers for distinguishing ICIs-related myocarditis from AMI, providing insights for clinical diagnosis and mechanistic research into immune-related cardiotoxicity.

Dictyostelium discoideum is a single-celled protist that undergoes multicellular development in response to nutrient deprivation. For close to a century, D. discoideum has been used as a model system for studying conserved cellular and developmental processes such as chemotaxis, cell adhesion, and cell differentiation. In the later decades of the 20th century, intensive research efforts examined the synthesis, trafficking, and activity of lysosomal enzymes in D. discoideum. Subsequent work revealed that lysosomes are essential for all stages of the D. discoideum life cycle and the genome encodes dozens of homologs of human lysosomal enzymes, including those associated with lysosomal storage diseases. Additionally, protocols for examining the trafficking and activity of lysosomal enzymes in D. discoideum are well-established. Here, we provide a comprehensive up-to-date review that summarizes our current knowledge of lysosomal enzyme processing and trafficking in D. discoideum, with an eye towards re-establishing D. discoideum as a model eukaryote for studying the functions of conserved lysosomal enzymes and the pathways that regulate their trafficking.

Antibiotics, specifically clindamycin (Clin), cause intestinal dysbiosis, reducing the microbiota with anti-inflammatory properties. Furthermore, Clin can induce alterations in the immune responses and oxidative stress. Lactoferrin, among other activities, participates in the maintenance of intestinal homeostasis and reduces dysbiosis induced by antibiotic treatment. The aim of this study was to analyze the effect of native and iron-saturated bovine LF in a murine model of dysbiosis induced by Clin. Six groups of male C57BL/6 mice were treated with saline (control), Clin, native lactoferrin (nLF), iron-saturated lactoferrin (sLF), nLF/Clin, or sLF/Clin. Oxidation caused in the intestinal cells of the ileum of animals subjected to different treatments was analyzed, focusing on lipid peroxidation and protein carbonyl content. The expression of inflammatory mediators was determined by qRT-PCR. Treatment with Clin did not modify lipid peroxidation, but significantly increased protein carbonyl levels up to almost 5-fold respect to the control, an effect that was reversed by orally administering sLF to mice. Furthermore, Clin increased the expression of interleukin-6 and TNF-α by 1- and 2-fold change, respectively. This effect was reversed by treatment with nLF and sLF, decreasing the expression to basal levels. In conclusion, this study indicates that lactoferrin can prevent some of the effects of Clin on intestinal cells and their associated immune system.

Human zyxin is a key component of the focal adhesion complex, playing a role in mediating cell-cell adhesion and cytoskeletal dynamics. Moreover, zyxin shuttles between the cytoplasm and the nucleus, where it contributes to regulating gene expression. Although identified over 30 years ago, zyxin's nuclear functions, particularly in relation to cancer, remain largely unexplored. In this study, we profiled zyxin binding to chromosomal DNA using metastatic prostate carcinoma PC3M cells as a model. Our ChIP-Seq results revealed that zyxin binds to chromosomal DNA, with mitochondrial pseudogenes as the primary targets. Furthermore, we demonstrated that the LIM domains of zyxin are sufficient for DNA binding and that zyxin knockdown leads to transcriptional changes in mitochondrial pseudogenes. Additionally, zyxin knockdown impacted several other genes associated with mitochondrial integrity and apoptosis, resulting in disturbances in MTCO2P2 RNA localization, mitochondrial membrane potential, increased reactive oxygen species, alterations in the cell cycle, and progression towards apoptosis. Overall, our work shows that zyxin directly interacts with nuclear DNA and regulates the transcription of mitochondrial pseudogenes, emphasizing its role in modulating mitochondrial function.

Pseudogenes, traditionally considered non-functional gene copies, have garnered attention due to emerging evidence of their transcription and translation. Ubiquitin is canonically expressed from UBA52 and RPS27A genes as fusion proteins, with additional polyubiquitin precursors encoded by UBB and UBC. Several pseudogenes of these loci are annotated as non-functional. Here, we report that the RPS27A pseudogene, RPS27AP5, expresses two proteins: a ubiquitin variant (UbP5) and a ribosomal protein variant (S27aP5). These proteins mature through cleavage and exhibit localization and biochemical characteristics similar to their parental counterparts. S27aP5 integrates into ribosomes, and its overexpression leads to an increased 80S monosome fraction. Using affinity purification and polysome profiling, we show that S27aP5-containing ribosomes exhibit altered mRNA associations. The findings suggest that RPS27A, a processed pseudogene, can give rise to a ribosomal protein variant capable of integrating into monosomes and influencing mRNA association aligns with growing evidence that ribosomes may exhibit functional diversity.

Our previous study showed antitumor activity of the complex formed by iron-free recombinant human lactoferrin (apo-recHLF) and oleic acid (OA) (1:8 molar ratio) in a model of murine hepatoma 22a inoculated to C3HA mice. Taken alone, apo-recHLF was less efficient; i.e., the tumor growth index was 0.14 for recHLF-8OA and 0.63 for recHLF as compared with 1.0 in the control animals. In the present study, we evaluated antitumor activity of iron-saturated recHLF per se and of the complexes formed by OA with apo-recHLF and holo-recHLF. Balb/c mice with solid myeloma Sp2/0 were subjected to the 10-day treatment with daily intraperitoneal (i/p) injections of 10 mg iron-saturated recHLF with OA (1:8) per animal (0.4 g/kg). In 15 days, the tumor growth was substantially inhibited. Mean tumor mass was 93% lower as compared with the control value (p < 0.01). I/p injections of apo-recHLF/OA complex did not inhibit the tumor growth. Holo-recHLF used without OA had less pronounced antitumor effect as compared with their complex.