Search Results (155)

Sarcopenia is characterized by a reduction in muscle function and skeletal muscle mass relative to that of healthy individuals. In older adults and those who are less resistant to sarcopenia, glucocorticoid secretion or accumulation during treatment exacerbates muscle protein degradation, potentially causing sarcopenia. This study assessed the preventive effects and mechanisms of heat-killed Lactobacillus plantarum postbiotic beLP-K (beLP-K) against dexamethasone (DEX)-induced sarcopenia in C2C12 myotubes and Sprague-Dawley rats. The administration of beLP-K did not induce cytotoxicity and mitigated cell damage caused by DEX. Furthermore, beLP-K significantly reduced the expression of forkhead box O3 α (FoxO3α), muscle atrophy f-box (MAFbx)/atrogin-1, and muscle RING-finger protein-1 (MuRF1), which are associated with muscle protein degradation. DEX induced weight loss in rats; however, in the beLP-K group, weight gain was observed. Micro-computed tomography analysis revealed that beLP-K increased muscle mass, correlating with weight and grip strength. beLP-K alleviated the DEX-induced reduction in grip strength and increased the mass of hind leg muscles. The correlation between beLP-K administration and increased muscle mass was associated with decreased expression levels of muscle degradation-related proteins such as MAFbx/atrogin-1 and MuRF1. Therefore, beLP-K may serve as a treatment for sarcopenia or as functional food material. Full article

We identified Murashka, a RING finger protein, in an oogenesis screen as a regulator of Drosophila ovary germline stem cell niche development. Mutant alleles of murashka exhibited an enlarged niche phenotype reminiscent of increased Notch signalling and displayed genetic interactions with Notch alleles, and with polychaetoid, a regulator of Notch during niche development. These interactions uncovered both positive and negative impacts on Notch in different genetic backgrounds. In S2 cells, Murashka formed a complex with Notch and colocalised with Notch in the secretory pathway. Murashka expression in S2 cells down-regulated Notch signalling levels but could result in increased fold induction due to the proportionally greater decrease in basal ligand-independent activity. In vivo Murashka expression had different outcomes on different Notch target genes. We observed a decrease in the expression of vestigial along the anterior/posterior boundary of the wing imaginal disc, but not of wingless at the dorsal/ventral boundary. Instead, weak ectopic wingless was observed, which was synergistically increased by the coexpression of Deltex, a positive regulator of ligand-independent signalling. Our results identify a novel developmental role for murashka, a gene previously only associated with a function in long-term memory, and indicate a regulatory role for Murashka through a physical interaction with Notch that has context-dependent outcomes. Murashka adds to a growing number of ubiquitin ligase regulators which interact with Notch at different locations within its secretory and endocytic trafficking pathways. Full article

Background/Objectives: Sarcopenia is an age-related disease resulting in muscle mass deterioration and declining strength and functional ability. Muscle protein degradation pathways are activated through the ubiquitin–proteasome system, which is integral to the pathogenesis of sarcopenia. This study examined the capability of Lactobacillus plantarum beLP1 as a postbiotic ingredient of kimchi that prevents sarcopenia. Methods: We evaluated cell viability and measured diameters in a C2C12 myotube damage model and muscle volume, muscle weight, muscle strength, and the expression of muscle degradation proteins MuRF1 and Atrogin-1 in dexamethasone-induced sarcopenic model rats using a heat-killed beLP1 strain. Results: beLP1 had no cytotoxic effects on C2C12 and prevented dexamethasone-induced cellular damage, suggesting its role in muscle protein degradation pathways. beLP1 treatment significantly prevented the dexamethasone-induced reduction in myotube diameter. In a dexamethasone-induced sarcopenic rat model, oral beLP1 significantly mitigated muscle mass decline and prevented grip strength reduction. Microcomputed tomography demonstrated that beLP1 reduced dexamethasone-induced muscle volume loss. beLP1 treatment reduced Atrogin-1 and Muscle RING-finger protein-1 (MuRF1) and the transcription factor Forkhead box O3 alpha (FoxO3α), which triggers muscle protein breakdown. beLP1 exerts protective effects by inhibiting the ubiquitin-proteasome system and regulating FoxO3α signaling. It increased AKT (Ser473) phosphorylation, which affected muscle protein synthesis, degradation, and cell survival, suggesting its potential to prevent sarcopenia. Conclusions: Heat-killed Lactobacillus plantarum beLP1 alleviates muscle mass wasting and weakness in a dexamethasone-induced sarcopenia model by regulating muscle protein degradation pathways and signaling molecules. Thus, postbiotics may be functional ingredients in sarcopenia prevention. Full article

RNA-binding E3 ubiquitin ligases (RBULs) provide a link between RNA metabolic processes and the ubiquitin proteasome system (UPS). In humans, RBULs are involved in various biological processes, such as cell proliferation and differentiation, as well as sexual development. To date, little is known about their role in the protozoan parasite Plasmodium falciparum, the causative agent of malaria tropica. We previously identified a novel P. falciparum RBUL, the RING finger E3 ligase PfRNF1, which is highly expressed during gametocyte development. Here, we conducted BioID-based proximity interaction studies to unveil the PfRNF1 interactome. We show that in immature gametocytes, PfRNF1 forms an interaction network that is mainly composed of RNA-binding proteins, including the translational repressors DOZI and CITH and members of the CCR4-NOT complex, as well as UPS-related proteins. In particular, PfRNF1 interacts with recently identified regulators of sexual development like the zinc finger protein PfMD3, with which it shares the majority of interactors. The common interactome of PfRNF1 and PfMD3 comprises several uncharacterized proteins predominantly expressed in male or female gametocytes. Our results demonstrate that PfRNF1 engages with RNA-binding proteins crucial for sex determination in gametocytes, thereby linking posttranscriptional regulation with the UPS. Full article

This overview explores the complex relationship between environmental factors, particularly obesity, and the timing of puberty, with a focus on how hormonal and genetic interactions are influenced by external conditions. Puberty (gonadarche) is characterised by the activation of the hypothalamic–pituitary–gonadal (HPG) axis. The onset and progression of puberty vary significantly among individuals, primarily due to genetic factors, with key genes like kisspeptin 1 (KISS1) and makorin ring finger protein 3 (MKRN3) playing a crucial role. Cohesively, this paper emphasises that environmental factors, particularly obesity and exposure to endocrine-disrupting chemicals (EDCs), have become significant influences on the timing of puberty. Childhood obesity has risen significantly in recent decades and the age of pubertal onset has declined over the same period. Obesity greatly disrupts hormone regulation in pre-pubertal children. Leptin accelerates the onset of puberty in girls but not in boys. The underlying mechanism is proposed to be the increase in Kiss1/GnRH signalling. On the contrary, excess leptin in boys suppresses testosterone production by increasing oestrogen conversion. Low adiponectin in obese girls may contribute to earlier puberty due to a reduced inhibition of Kiss1/GnRH signalling. Low adiponectin in boys is linked to delayed puberty due to its role in maintaining insulin sensitivity and testosterone production. Hyperinsulinemia influences pubertal timing through central and peripheral mechanisms. Insulin acting synergistically with leptin promotes the earlier onset of puberty in girls but not in boys. The effects of exposure to certain EDCs—mostly obesogenic chemicals that mimic the action of natural hormones—on the timing of puberty remain unclear; hence, further research on this topic is needed. Addressing and preventing obesity in children could potentially mitigate these alterations in pubertal timing. Full article

MuRF1 [muscle RING (Really Interesting New Gene)-finger protein-1] is an ubiquitin-protein ligase (E3), which encode by TRIM63 (tripartite motif containing 63) gene, playing a crucial role in regulating cardiac muscle size and function through ubiquitylation. Among hypertrophic cardiomyopathy (HCM) patients, 24 TRIM63 variants have been identified, with 1 additional variant linked to restrictive cardiomyopathy. However, only three variants have been previously investigated for their functional effects. The structural impacts of the 25 variants remain unexplored. This study investigated the effects of 25 MuRF1 variants on ubiquitylation activity using in vitro ubiquitylation assays and structural predictions using computational approaches. The variants were generated using site-directed PCR (Polymerase Chain Reaction) mutagenesis and subsequently purified with amylose affinity chromatography. In vitro ubiquitylation assays demonstrated that all 25 variants compromised the ability of MuRF1 to monoubiquitylate a titin fragment (A168-A170), while 17 variants significantly impaired or completely abolished auto-monoubiquitylation. Structural modelling predicted that 10 MuRF1 variants disrupted zinc binding or key stabilising interactions, compromising structural integrity. In contrast, three variants were predicted to enhance the structural stability of MuRF1, while six others were predicted to have no discernible impact on the structure. This study underscores the importance of functional assays and structural predictions in evaluating MuRF1 variant pathogenicity and provides novel insights into mechanisms by which these variants contribute to HCM and related cardiomyopathies. Full article

Muscle atrophy leads to decreased muscle mass, weakness, inactivity, and increased mortality. E3 ubiquitin ligases, key regulators of protein degradation via the ubiquitin–proteasome system, play a critical role in atrophic mechanisms. This meta-analysis followed Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, and its objective was to evaluate the association between E3 ligases Muscle Atrophy F-box (MAFbx)/Atrogin-1 (Fbxo32) and Muscle RING-finger protein 1 (MuRF-1) (TRIM63) E3 ligase mRNA levels, reductions in skeletal muscle CSA measures, and atrophy conditions. We examined papers published on PubMed^®, Scopus, and Web of Science that studied E3 ligase gene expression signatures for Fbxo32 (MAFbx/Atrogin-1) and Trim63 (MuRF1) in different types of muscle atrophy and hypertrophy murine models. Twenty-nine studies selected by two independent raters were analyzed. Standardized mean differences (SMDs)/effect sizes (ESs) and 95% confidence intervals (CIs) were calculated for the outcomes using fixed-effects models. We found that 6- and 4.8-fold upregulation, respectively, of Fbxo32 and Trim63 was sufficient to reduce the ES to −3.89 (95% CI: −4.45 to −3.32) for the muscle fiber cross-sectional area and the development of skeletal muscle atrophy. I² and Q test statistics did not indicate heterogeneous data. There was a low probability of bias after both the funnel plot and Egger’s test analyses. These results were sustained independently of the atrophic model and muscle type. Therefore, the magnitude of the increase in muscle Fbxo32 and Trim63 mRNA is a feasible, reliable molecular marker for skeletal muscle atrophy in mice. The next step for the Ubiquitin-proteasome system (UPS) field involves elucidating the targets of E3 ligases, paving the way for diagnostic and treatment applications in humans. Full article

Metabolic-associated fatty liver disease (MAFLD) is a chronic liver condition with limited therapeutic options. To identify novel drug targets, we integrated bioinformatics, Mendelian randomization (MR), and colocalization analyses. Using the Gene Expression Omnibus (GEO) database, we identified differentially expressed genes and constructed protein–protein interaction (PPI) networks, pinpointing 10 hub genes. MR and colocalization analyses revealed that Ubiquitin-like with PHD and ring finger domains 1 (UHRF1) is causally associated with MAFLD and driven by the same causal variant locus, suggesting its potential as a therapeutic target. Molecular docking identified disogenin as a candidate small-molecule drug targeting UHRF1. Drug affinity responsive target stability (DARTS) assays confirmed direct binding between UHRF1 and disogenin. In vitro, disogenin significantly reduced UHRF1 mRNA and protein levels induced by free fatty acids (FFA) in AML12 and HepG2 cells, accompanied by decreased cellular total cholesterol (TC) and triglyceride (TG) levels. In vivo, disogenin administration alleviated hepatic lipid accumulation, inflammation, and fibrosis in methionine/choline-deficient (MCD)-diet-fed mice. This study identifies UHRF1 as a promising therapeutic target for MAFLD and validates disogenin as a potential therapeutic agent, providing a foundation for further investigation. Full article

B30.2 domains, sometimes referred to as PRY/SPRY domains, were originally identified by sequence profiling methods at the gene level. The B30.2 domain comprises a concanavalin A-like fold consisting of two twisted seven-stranded anti-parallel β-sheets. B30.2 domains are present in about 150 human and 700 eukaryotic proteins, usually fused to other domains. The B30.2 domain represents a scaffold, which, through six variable loops, binds different unrelated peptides or endogenous low-molecular-weight compounds. At the cellular level, B30.2 proteins engage in supramolecular assemblies with important signaling functions. In humans, B30.2 domains are often found in E3-ligases, such as tripartite motif (Trim) proteins, SPRY domain-containing SOCS box proteins, Ran binding protein 9 and −10, Ret-finger protein-like, and Ring-finger proteins. The B30.2 protein recognizes the target and recruits the E2-conjugase by means of the fused domains, often involving specific adaptor proteins. Further well-studied B30.2 proteins are the methyltransferase adaptor protein Ash2L, some butyrophilins, and Ryanodine Receptors. Although the affinity of an isolated B30.2 domain to its ligand might be weak, it can increase strongly due to avidity effects upon recognition of oligomeric targets or in the context of macromolecular machines. Full article

Diabetic kidney disease (DKD) is a prevalent complication associated with diabetes in which podocyte dysfunction significantly contributes to the development and progression of the condition. Ring finger protein 183 (RNF183) is an ER-localized, transmembrane ring finger protein with classical E3 ligase activity. However, whether RNF183 is involved in glomerular podocyte dysfunction, which is the mechanism of action of DKD, is still poorly understood. In this study, we first demonstrated that RNF183 expression in glomerular podocytes of patients with DKD decreased as the disease progressed. Additionally, our transcriptome sequencing analysis of kidney tissues from diabetic mice revealed a significant reduction in RNF183 expression within the kidney cortex. Similarly, the expression of RNF183 was significantly reduced both in the kidneys of diabetic mice and in human podocytes exposed to high glucose conditions. The downregulation of RNF183 resulted in a suppression of autophagic activity, an increase in apoptotic cell death, and reduced expression of cellular markers in HPC cells. We found that RNF183 was modified via N6-methyladenosine (m6A) RNA methylation. Meanwhile, treatment with meclofenamic acid 2 (MA2), an m6A demethylase inhibitor, resulted in the upregulation of RNF183 expression in HPC cells cultured in high glucose conditions. Furthermore, high glucose treatment decreased the transcription and protein levels in both the m6A writer methyltransferaselike3 (METTL3) and the m6A reader insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2). IGF2BP2 assisted with METTL3, which is jointly involved in the transcription of RNF183. Furthermore, we confirmed that RNF183 directly ubiquitinates M2 pyruvate kinase (PKM2) through co-immunoprecipitation (Co-IP) and liquid chromatography–mass spectrometry (LC-MS) experiments. The level of PKM2 ubiquitination was increased following RNF183 overexpression, leading to enhanced PKM2 protein degradation and subsequently alleviating high glucose-induced podocyte damage. The results of this study indicated that RNF183 was regulated via m6A methylation modification and that RNF183 expression was reduced in HPC cells treated with high glucose, which resulted in decreased PKM2 ubiquitination levels and subsequently aggravated podocyte injury. The findings suggest that RNF183 may serve as a potential therapeutic target for diabetic kidney injury, offering new insights into its role in the progression of DKD. Full article

Background/Objectives: Muscle-specific RING finger protein 1 (MuRF-1) is a pivotal regulator of muscle protein breakdown, an essential process for post-exercise muscle adaptation. This systematic review aimed to evaluate the effects of physical exercise on MuRF-1 mRNA expression in humans. Methods: A literature search was conducted in PubMed, Scopus, Cochrane Library, Google Scholar, and Web of Science following the PRISMA guidelines. The search was limited to studies published from 1 January 2001 to 1 December 2024. The inclusion and exclusion criteria were defined using the PICOS strategy. Two investigators independently performed the study selection, data extraction, and assessment of methodological quality, with any disagreements resolved by a third investigator. The PEDro scale was used to evaluate the risk of bias. Results: Forty-six studies met the eligibility criteria and were included. The findings evidenced that physical exercise significantly modulates MuRF-1 mRNA expression in humans. Resistance exercise induces transient increases, typically peaking between 1 and 4 h, whereas endurance exercise elicits similar responses within 40 min to 4 h post-exercise. Combined exercise protocols that include resistance and endurance exercises significantly increased MuRF-1 mRNA expression at 3 h post-exercise. The effects of physical exercise on MuRF-1 mRNA expression are influenced by factors such as exercise order, intensity, contraction mode, age, sex, and fitness level. Conclusions: This systematic review shows that MuRF-1 mRNA expression is significantly modulated by physical exercise in humans and is sensitive to different exercise modalities. These findings suggest that this key protein involved in muscle protein breakdown and turnover is essential for exercise-induced adaptations, contributing to skeletal muscle recovery and remodeling after exercise. Full article

ORF2p (open reading frame 2 protein) is a multifunctional multidomain enzyme that demonstrates both reverse transcriptase and endonuclease activities and is associated with the pathophysiology of cancer. The 3D structure of the entire seven-domain ORF2p complex was revealed with the recent achievements in structural studies. The different arrangements of the CTD (carboxy-terminal domain) and tower domains were identified as the “closed-ring” and “open-ring” conformations, which differed by the hairpin position of the tower domain, but the structural diversity of these complexes has the potential to be more extensive. To study this, we performed sub-microsecond all-atom molecular dynamics simulations of the entire ORF2p complex with different starting configurations. The obtained molecular dynamic trajectories frames were assigned to several clusters following the dimension reduction to three principal components of the 1275 distances feature matrix. Five and six clusters were obtained for the “open” and “closed” ring models, respectively. While the fingers–palm–thumb core retains its rigid configuration during the MD (molecular dynamics) simulations, all other domains display the complicated dynamic behavior not observed in the experimental structures. The EN (endonuclease) and CTD domains display significant translations and rotations while their internal structures stay rigid. The CTD domain can either form strong contacts with the tower or be far apart from it for both formal “open” and “closed” ring states because the tower hairpin position is not the only determining factor of the protein complex configuration. While only the “thumb up” conformation is observed in all the trajectories, the active site can be obstructed by the movement of the CTD domain. Thus, molecular modeling and machine learning techniques provide valuable insights into the dynamical behavior of the ORF2p complex, which is hard to uncover with experimental methods, given the complexity and size of the object. Full article

The objective of this study was to examine whether fucosterol, a phytosterol of marine algae, could ameliorate skeletal muscle atrophy in tumor necrosis factor-alpha (TNF-α)-treated C2C12 myotubes and in immobilization-induced C57BL/6J mice. Male C57BL6J mice were immobilized for 1 week to induce skeletal muscle atrophy. Following immobilization, the mice were administrated orally with saline or fucosterol (10 or 30 mg/kg/day) for 1 week. Fucosterol significantly attenuated immobilization-induced muscle atrophy by enhancing muscle strength, with a concomitant increase in muscle volume, mass, and myofiber cross-sectional area in the tibialis anterior (TA) muscle in mice. In both the TNF-α-treated C2C12 myotubes and the TA muscle of immobilized mice, fucosterol significantly prevented muscle protein degradation, which was attributed to a reduction in atrogin-1 and muscle ring finger 1 gene expression through an increase in forkhead box O3α (FoxO3α) phosphorylation. Continuously, fucosterol stimulated muscle protein synthesis by increasing the phosphorylation of the mammalian target of the rapamycin (mTOR), 70 kDa ribosomal protein S6 kinase, and 4E binding protein 1, which was mediated through the stimulation of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. Thus, fucosterol alleviated skeletal muscle atrophy in TNF-α-treated C2C12 myotubes and immobilized C57BL/6J mice through the regulation of the Akt/mTOR/FoxO3α signaling pathway. Full article

Background: Altered gene expression in cancers holds great potential to improve the diagnostics and differentiation of primary and metastatic liver cancers. In this study, the expression of the protein-coding genes ring finger protein 135 (RNF135), ephrin-B2 (EFNB2), ring finger protein 125 (RNF125), homeobox-C 4 (HOXC4), actin-binding LIM protein 1 (ABLIM1) and oncostatin M receptor (OSMR) and the long non-coding RNAs (lncRNA) prospero homeobox 1 antisense RNA 1 (PROX1-AS1) and leukemia inhibitory factor receptor antisense RNA 1 (LIFR-AS1) was investigated in hepatocellular carcinoma, cholangiocarcinoma, colorectal liver metastases and pancreatic ductal adenocarcinoma liver metastases. Methods: This study included 149 formalin-fixed, paraffin-embedded samples from 80 patients. After RNA isolation, quantification, reverse transcription and preamplification, real-time qPCR was performed. The gene expression between different groups was calculated relative to the expression of the reference genes using the ∆∆Cq method and statistically analyzed. The expression of the genes was additionally analyzed using the AmiCA and UCSC Xena platforms. Results: In primary cancers, our results showed differential expression between primary tumors and healthy tissues for all the genes and lncRNA examined. Moreover, we found downregulation of RNF135 in hepatocellular carcinoma, downregulation of OSMR in colorectal liver metastases and upregulation of HOXC4 in cholangiocarcinoma compared to primary liver cancers and metastatic cancers. The major finding is the upregulation of ABLIM1 in cholangiocarcinoma compared to hepatocellular carcinoma, colorectal liver metastases, pancreatic ductal adenocarcinoma liver metastases and healthy liver tissue. We propose ABLIM1 as a potential biomarker that differentiates cholangiocarcinoma from other cancers and healthy liver tissue. Conclusions: This study emphasizes the importance of understanding the differences in gene expression between healthy tissues and primary and metastatic cancers and highlights the potential use of altered gene expression as a diagnostic biomarker in these malignancies. Full article

Multiple Sclerosis (MS) is an autoimmune neurodegenerative disease affecting approximately 3 million people globally. Despite rigorous research on MS, aspects of its development and progression remain unclear. We utilized a publicly available RNA-seq dataset (GSE138614) consisting of the post-mortem white matter tissues of five donors without any neurological disorders and ten MS patient donors. We investigated gene expression levels correlated with tissue inflammation and alternative splicing to identify possible pathological isoforms in MS tissues. We identified RNA-binding motifs, differentially expressed RNA-binding proteins, and single-nucleotide polymorphisms (SNPs) to unravel possible mechanisms of alternative splicing. Genes with expression changes that were positively correlated with tissue inflammation were enriched in the immune system and receptor interaction pathways. Genes showing a negative correlation were enriched in nervous system development and in metabolic pathways. A comparison of normal-appearing white matter (NAWM) and active or chronic active lesions within the same donors identified genes playing roles in immunity, white matter injury repair, and remyelination. We identified exon skipping events and spontaneous SNPs in membrane-associated ring-CH-type finger-1 (MARCHF1), UDP glycosyltransferase-8 (UGT8), and other genes important in autoimmunity and neurodegeneration. Overall, we identified unique genes, pathways, and novel splicing events that can be further investigated as potential novel drug targets for MS treatment. Full article