Genes to Cells最新文献

Type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatohepatitis (MASH) frequently coexist and are mechanistically linked via insulin resistance, lipotoxicity, and chronic inflammation. Cholic acid (CA), a primary bile acid (BA), modulates metabolic and immune pathways by influencing BA composition and the gut microbiota. In this study, we examined the role of dietary CA in the modulation of T2DM and MASH in Tsumura Suzuki obese diabetes (TSOD) mice, a model of spontaneous obesity and diabetes. Mice were fed a high-fat, high-cholesterol diet with or without CA (iHFC and CA(−) iHFC diets, respectively). CA supplementation significantly improved hyperglycemia and hyperinsulinemia, independent of adipose tissue inflammation. These metabolic benefits were associated with an increased intestinal abundance of Akkermansia muciniphila and elevated ileal expression of fibroblast growth factor 15 (FGF-15), suggesting activation of the FXR–FGF-15 axis. However, CA also exacerbated MASH, accompanied by increased hepatic inflammation, fibrosis, and accumulation of hepatotoxic BAs, including deoxycholic acid and taurodeoxycholic acid. The removal of CA mitigated these hepatic changes while abolishing glycemic improvement. Accordingly, CA can exert opposing effects in TSOD mice—ameliorating T2DM while worsening MASH—highlighting the need for caution when targeting BA pathways in metabolic diseases.

Cellular senescence is caused by various stresses, including DNA damage, oxidative stress, oncogene activation, and telomere shortening. However, the detailed molecular mechanisms of cellular senescence have yet to be elucidated. Recently, using comparative transcriptomics and quantitative PCR, we identified several genes that are specifically upregulated in senescent cells in a p53-dependent manner, including Epsin 3 (EPN3). However, the functional relevance of EPN3 to senescence has not yet been defined. Here, we performed functional analyses to investigate the relationship between EPN3 and the senescence program. We found that EPN3 knockdown suppressed senescent phenotypes induced by DNA damage. Furthermore, ectopic expression of EPN3 induced senescence accompanied by increased reactive oxygen species (ROS) and accumulation of DNA damage. Furthermore, EPN3-induced DNA damage was suppressed by genetic and pharmacological inhibition of Rac1. Finally, treatment with ROS scavengers, N-acetyl-l-cysteine (NAC) and l-Ascorbic Acid (LAA), prevented EPN3-induced DNA damage, and a Rac1 inhibitor reduced ROS levels in EPN3-expressing stable clones. These results indicate that EPN3 induces DNA damage and promotes senescence via Rac1 activity and ROS generation.

Primary human hepatocytes (PHHs) are currently the gold standard for developing human-relevant in vitro liver cell culture models for studies of pathological conditions, compound screening, and metabolism and toxicity testing in the drug discovery process. However, PHHs exhibit variable adhesiveness to culture vessels, which limits their utility. In this study, we investigated the cause of this unstable adhesiveness of PHHs. We observed that non-adhering PHHs have some kind of extracellular matrix (ECM) on the surface, and these ECMs inhibit cell adhesion to culture vessels. Removal of ECMs from the cell surface of non-adhering PHHs improved the attachment of the cells to culture vessels. Our findings yield a method to generate stable adhesion cultures of PHHs and contribute to developing hepatocyte research by expanding hepatocyte applications.

Lysosomes are acidic organelles that degrade a diverse range of substrates, and lysosome-associated membrane protein (LAMP)-1 and LAMP-2 are the major lysosomal membrane components. Three LAMP-2 splice variants have been identified, namely, LAMP-2A, LAMP-2B, and LAMP-2C. We previously demonstrated that when mouse LAMP-2C was stably expressed in HEK293 cells, a portion of it was present on the plasma membrane. LAMP-2C possesses a tyrosine-based motif that functions as a signal for lysosomal targeting and clathrin-mediated endocytosis (CME). However, whether cell surface LAMP-2C is indeed internalized via CME has not been clearly defined. If this occurs, it is unknown whether internalized LAMP-2C returns to the cell surface and/or moves to lysosomes from early endosomes. In this study, we found that cell surface LAMP-2C was internalized, and its internalization was impaired by knockdown of the clathrin heavy chain or the medium subunit of adaptor protein complex 2. Internalized LAMP-2C was transported to early endosomes, and a portion of the internalized LAMP-2C was recycled back to the plasma membrane. Furthermore, immunofluorescence and subcellular fractionation showed that the internalized LAMP-2C was transported to lysosomes. These results suggest that cell surface LAMP-2C is internalized by CME and that internalized LAMP-2C enters the recycling and lysosomal pathways.

Hepatocellular carcinoma (HCC) is a prevalent and deadly cancer worldwide, characterized by poor prognosis, multiple therapeutic challenges, and considerable heterogeneity among patients with diverse etiologies. This heterogeneity contributes to resistance to chemotherapies and molecularly targeted agents, posing a major therapeutic challenge. Therefore, there is an increasing need for treatment strategies targeting HCC across various biological processes. miR-192-5p has been reported to function as a tumor suppressor in HCC, but its target genes remain largely unknown. In this study, we aimed to identify novel target genes of miR-192-5p in HCC using RNA sequencing and 3′-untranslated region analysis. As a result, eight genes—EFEMP1, DLG5, PPP1CA, FAM234B, RPL4, SEC23B, ELOVL1, and CBFB—were identified as novel target genes of miR-192-5p, all of which were significantly upregulated in HCC tissues. Notably, three genes—CBFB, SEC23B, and RPL4—were also validated as novel targets of miR-194-5p, which clusters with miR-192-5p. These findings suggest that miR-192-5p exerts its tumor-suppressive function by inhibiting a novel gene network that may contribute to HCC progression. This study provides new insights into the molecular mechanisms underlying HCC heterogeneity and highlights miR-192-5p-regulated networks as potential therapeutic targets for HCC.