No abstract

Depression and obesity have high concurrence within individuals, which may be explained by sharing the same risk factors, including disruption of the intestinal microbiota. However, evidence that delineated the causal connections is extremely scarce. Methods: Mice lacking fat mass- and obesity-associated gene ( Fto ) were generated. Fto -deficient and wild-type control mice were subjected to novel conditions with or without chronic unpredictable mild stress (CUMS) for 6 weeks. Some mice were treated with antibiotics via their drinking water for 6 weeks in order to deplete their microbiota. Behavioral tests were performed to evaluate anxiety- and depression-like behaviors. 16S rRNA amplicon and metagenomic sequencing were employed to analyse fecal microbiota. Plasma levels of inflammatory cytokines and lipopolysaccharides (LPS) were also compared. Results: Deletion of Fto led to lower body weight and decreased anxiety- and depression-like behaviors, Fto +/- mice were also less susceptible to stress stimulation, highlighting the essential role of Fto in pathogenesis of depression. With regard to gut microbiota, Fto deficiency mice harbored specific bacterial signature of suppressing inflammation, characterized with higher abundance of Lactobacillus , lower Porphyromonadaceae and Helicobacter . Critically, behavioral alterations of Fto +/- mice are mediated by shift in gut microbiota, as such changes can be partially attenuated using antibiotics. Exposure to CUMS increased serum IL-6 level while Fto deficiency reduced its level, which may be explained by a lower LPS concentration. Conclusion: Together, our findings uncover the roles of Fto on depression and provide insights into microbiota-related biological mechanisms underlying the association between obesity and depression.

Cryptococcus neoformans is an important opportunistic fungal pathogen in humans. Recent studies have demonstrated that metals are critical factors for the regulation of fungal virulence in hosts. In this study, we systemically investigated the function of C. neoformans magnesium transporters in controlling the intracellular Mg balance and virulence‐associated factors. We identified three Mg transporters in C. neoformans: Mgt1, Mgt2, and Mgt3. While we could not detect a Mg2+‐related growth phenotype in mgt1 and mgt3 knockout strains, a GAL7p‐Mgt2 strain showed significant Mg‐dependent growth defects in the presence of glucose. Further analysis demonstrated that MGT2 is a homolog of MNR2 in Saccharomyces cerevisiae, which is localized to the vacuolar membrane and participates in intracellular Mg transport. Interestingly, a transcriptome analysis showed that Mgt2 influenced the expression of 19 genes, which were independent of Mg2+. We showed that melanin synthesis in C. neoformans required Mg2+ and Mgt2, and that capsule production was negatively regulated by Mg2+ and Mgt2. Repressing the expression of MGT2‐induced capsule, which resulted in an increased fungal burden in the lungs. Cumulatively, this study sets the stage for further evaluation of the important role of Mg homeostasis in the regulation of melanin and capsule in C. neoformans.

Wnt/β-catenin signaling is a conserved pathway crucially governing development, tissue homeostasis and oncogenesis in metazoan. Through screening, we identified a deubiquitinase (DUB) USP10 as a novel modulator of Wnt/β-catenin signaling. Mechanistically, USP10 binds to Axin1 via conserved motifs and stabilizes Axin1 through K48-linked deubiquitination. And in parallel, USP10 tethers Axin1 and β-catenin physically, via stabilizing the phase separation of Axin1 through its intrinsically-disordered regions, which is regardless of its enzymatic activity. Functionally, we show USP10 prominently regulates zebrafish embryonic development and murine intestinal homeostasis by antagonizing Wnt/β-catenin signaling. Additionally in human colorectal cancer, USP10 substantially represses cancer growth and correlates with Wnt/β-catenin magnitude clinically. Collectively, we discovered USP10 functioning in multiple biological processes through repressing Wnt/β-catenin signaling and unearthed a novel DUB-dependent and -independent dual-regulating mechanism by which USP10 utilizes in Wnt regulation context-dependently. Our study also suggested the potential of USP10 inhibitor in treating Wnt-related diseases.