Project description:Abstract: Interruption of bile acid recirculation through inhibition of the apical sodium-dependent bile acid transporter (ASBT) is a promising strategy to alleviate hepatic cholesterol accumulation in non-alcoholic steatohepatitis, and improve the metabolic aspects of the disease. Putative disease-attenuating effects of the ASBT inhibitor volixibat (5, 15, and 30 mg/kg) were investigated in high-fat diet (HFD)-fed Ldlr-/-.Leiden mice over 24 weeks. Plasma and fecal bile acid levels, plasma insulin, lipids, and liver enzymes were monitored. Final analyses included liver histology, intrahepatic lipids, mesenteric white adipose tissue mass, and liver gene profiling. Consistent with its mechanism of action, volixibat significantly increased total bile acid excretion. At the highest dose, volixibat significantly attenuated the HFD-induced increase in hepatocyte hypertrophy, hepatic triglyceride and cholesteryl ester levels, and mesenteric white adipose tissue deposition, while total plasma bile acid levels remained constant. Non-alcoholic fatty liver disease activity score was significantly lower in volixibat-treated mice than in the HFD controls. Gene profiling showed that volixibat reversed the inhibitory effect of the HFD on metabolic master regulators, including peroxisome proliferator-activated receptor-γ coactivator-1β, insulin receptor, and sterol regulatory element-binding transcription factor 2. Volixibat may have beneficial effects on physiological and metabolic aspects of non-alcoholic steatohepatitis pathophysiology.
Project description:Apical sodium-dependent bile acid transporter inhibition with volixibat improves metabolic aspects and components of non-alcoholic steatohepatitis in Ldlr-/-.Leiden mice
Project description:Cholestasis may cause cholemic nephropathy that can be modelled in common bile duct ligated (CBDL) mice. We aimed to explore the therapeutic efficacy and mechanisms of norursodeoxycholic acid (norUDCA) in cholemic nephropathy. To determine whether norUrsodeoxycholic acid (norUDCA) prevents cholemic nephropathy in long-term CBDL mice, a norUDCA-enriched diet (0.125% w/v, corresponding to 200 mg/kg/day for a mouse of 25 g body weight eating about 4g daily) or a standard mouse diet (Sniff, Soest, Germany) were started 5 days prior to CBDL and were continued until harvesting 3 weeks thereafter. For transcriptional profiling using microarray technology, we compared sham-operated (SOP) mice and 3-week CBDL mice that were either fed 0.125% norUDCA-enriched or standard mouse diets.
Project description:<p>The central nervous system has been implicated in the age-induced reduction in adipose tissue lipolysis. SLC7A14 is a lysosomal membrane protein highly expressed in the brain. Herein, we investigated the possible role of hypothalamic SLC7A14 in the age-induced lipolysis reduction. In this study, we demonstrated the expression of SLC7A14 was reduced in proopiomelanocortin (POMC) neurons of aged mice. Overexpression of SLC7A14 in POMC neurons alleviated the age-induced reduction in white adipose tissue (WAT) lipolysis, whereas SLC7A14 deletion mimicked the age-induced lipolysis impairment. Moreover, POMC SLC7A14 regulated WAT lipolysis independently of sympathetic nerves in WAT. Metabolomics analysis revealed that POMC SLC7A14 increased the primary bile acid taurochenodeoxycholic acid (TCDCA) content, which mediated the SLC7A14 knockout- or age-induced WAT lipolysis impairment. Furthermore, SLC7A14-increased TCDCA content is dependent on intestinal apical sodium-dependent bile acid transporter (ASBT), which is regulated by intestinal sympathetic afferent nerves. Finally, SLC7A14 regulated the intestinal sympathetic afferent nerves by inhibiting mTORC1 signaling through inhibiting TSC1 phosphorylation. Collectively, our study suggests the function for central SLC7A14 and an upstream mechanism for the mTORC1 signaling pathway. Moreover, our data provides insights into the brain-gut-adipose tissue crosstalk in age-induced lipolysis impairment.</p>
Project description:Tight control of both extracellular and intracellular inorganic phosphate (Pi) levels is critical to the normal functioning of virtually all biochemical and physiological processes. The kidney participates in Pi homeostasis by controlling Pi reabsorption from the primary urine. Pi is freely filtered at the kidney glomerulus and is reabsorbed in the renal tubule by the action of the apical sodium-dependent phosphate transporters NaPi-IIa/NaPi-IIc/Pit2. The molecular identity of transporter(s) involved in the basolateral Pi efflux remains unknown. Recent evidence has suggested that the retroviral receptor XPR1 might be a candidate for this role. Here we show that conditional inactivation of Xpr1 in the renal tubule in mice results in impaired renal Pi reabsorption associated with a generalized proximal tubular dysfunction, or Fanconi syndrome, characterized by glycosuria, aminoaciduria, calciuria and albuminuria. Bone histomorphometry showed that the Xpr1-deficient mice develop hypophosphatemic osteomalacia secondary to the renal dysfunction. The analysis of Pi transport in primary culture of the proximal tubular cells revealed that the Pi efflux was significantly affected in cells devoid of Xpr1. These results identify XPR1 as a major player in Pi homeostasis and as a potential therapeutic target in bone and kidney disorders.
Project description:Single-Cell Analysis of the Liver Epithelium Reveals Dynamic Heterogeneity and an Essential Role for YAP in Homeostasis and Regeneration The liver is an essential organ with compartmentalized metabolic processes and significant regenerative capabilities. Repopulation of the liver parenchyma can transpire from both main epithelial cell types, hepatocytes and biliary epithelial cells (BECs). Here, we harness high-throughput single-cell RNA sequencing (scRNA-seq) to dissect the transcriptional heterogeneity and cellular diversity of these epithelial compartments in homeostasis and injury. Our data argue against the idea of a rigidly defined liver progenitor cell in BECs, finding instead that heterogeneity in homeostatic BECs is principally distinguished by a YAP-dependent program that defines a dynamic cellular state. We report that this cellular state dynamically fluctuates between BECs and can be induced in the majority of BECs in response to environmental stimuli and injury. Functional studies demonstrate that YAP is distinctly required for BEC survival in homeostasis, uncovering a tight physiological necessity for YAP signaling in BECs compared to other tissues. YAP is also essential for hepatocyte reprogramming towards a ductal progenitor fate upon injury. Finally, our data demonstrate that this YAP-driven cellular state is highly responsive to injury by physiological exposure to bile acids (BAs) via apical sodium-bile acid transporter, and that sequestration of endogenous BAs rescues the cell loss phenotype associated with homeostatic Yap deletion. Together, our findings uncover previously undescribed molecular heterogeneity within the ductal epithelium and highlight a distinct and potent role for YAP as a protective rheostat and regenerative regulator in the mammalian liver.
Project description:Renal tubulointerstitial fibrosis is the pathological feature of AAN. Aristolochic acid nephropathy (AAN)was induced by a one-time intraperitoneal injection of aristolochic acid in PBS. By RNA sequencing analysis in AAN mice, we observed the significant changes of genes important in regulating cell cycle.
Project description:Hypertensive nephropathy is a common complication of hypertension that places a heavy burden on society. SGLT2 inhibitors are a new class of hypoglycemic agents that have been shown to have specific protective effects on the kidneys. This study aimed to investigate the early changes in renal transcription spectrum in spontaneously hypertensive rats and the effects of DAPA, a sodium-glucose cotransporter 2 inhibitor, on the remission of hypertensive nephropathy and its underlying molecular mechanisms. We furthermore show thatSGLT2 inhibitors may reduce inflammation and improve energy metabolism by regulating the expression of SLC9a3, Zbtb20, Trim50 and Ccnl2.
Project description:The study used a clinically relevant mouse model of chronic aristolochic acid nephropathy (AAN) to investigate the responses of proximal tubular cells during kidney fibrosis by single-nucleus RNA sequencing. The experiment involved 4 mice with AAN induced chronic renal fibrosis and 4 naive controls.