Kotlinowski, J. | Search bioRxiv

bioRxiv2020

Role of Mcpip1 in obesity-induced hepatic steatosis as determined by myeloid and liver-specific conditional knockouts.

Monocyte chemoattractant protein-induced protein 1 (MCPIP1, alias Regnase1) is a negative regulator of inflammation, acting through cleavage of transcripts coding for proinflammatory cytokines and by inhibition of NF{kappa}B activity. Moreover, it was demonstrated, that MCPIP1 regulates lipid metabolism both in adipose tissue and hepatocytes. In this study, we investigated the effects of tissue-specific Mcpip1 deletion on the regulation of hepatic metabolism and development of non-alcoholic fatty liver disease (NAFLD). We used knock-in control Mcpip1fl/fl mice and animals with deletion of Mcpip1 in myeloid leukocytes (Mcpip1fl/flLysMCre) and in hepatocytes (Mcpip1fl/flAlbCre), which were fed chow or a high-fat diet (HFD) for 12 weeks. Mcpip1fl/flLysMCre mice were fed a chow diet were characterized by a significantly reduced hepatic expression of genes regulating lipid and glucose metabolism, which subsequently resulted in hypoglycemia and dyslipidemia. These animals also displayed systemic inflammation, demonstrated by increased concentrations of cytokines in the plasma. On the other hand, there were no significant changes in phenotype in Mcpip1fl/flAlbCre mice. Although we detected a reduced hepatic expression of genes regulating glucose metabolism and {beta}-oxidation in these mice, they remained asymptomatic. Upon feeding them a HFD, Mcpip1fl/flLysMCre mice did not develop obesity, glucose intolerance, nor hepatic steatosis, but were characterized by hypoglycemia and dyslipidemia, along with proinflammatory phenotype with symptoms of cachexia. Mcpip1fl/flAlbCre animals, following a HFD, became hypercholesterolemic, but accumulated lipids in the liver at the same level as Mcpip1fl/fl mice, and no changes in the level of soluble factors tested in the plasma were detected. In conclusion, we have demonstrated that Mcpip1 protein plays an important role in the liver homeostasis. Depletion of Mcpip1 in myeloid leukocytes, followed by systemic inflammation, has a more pronounced effect on controlling liver metabolism and homeostasis than the depletion of Mcpip1 in hepatocytes.

molecular biology↗

bioRxiv2020

Deletion of Mcpip1 in Mcpip1AlbKO mice recapitulates the phenotype of human primary biliary cholangitis

Background & AimsPrimary biliary cholangitis (PBC) is an autoimmune disease characterized by progressive destruction of the intrahepatic bile ducts. The immunopathology of PBC involves excessive inflammation; therefore, negative regulators of inflammatory response, such as Monocyte Chemoattractant Protein-1-Induced Protein-1 (MCPIP1, alias Regnase1) may play important roles in the development of PBC. The aim of this work was to verify whether Mcpip1 expression protects against development of PBC. MethodsGenetic deletion of Zc3h12a was used to characterize the role of Mcpip1 in the pathogenesis of PBC. 6-52-week-old Mcpip1fl/fl and Mcpip1AlbKO mice were used for immunohistochemical, biochemical and molecular tests. ResultsWe found that Mcpip1 deficiency in the liver recapitulates most of the features of human PBC, in contrast to mice with Mcpip1 deficiency in myeloid cells (Mcpip1LysMKO mice), which present with robust myeloid cell-driven systemic inflammation. In Mcpip1AlbKO livers, intrahepatic bile ducts displayed proliferative changes with inflammatory infiltration, bile duct destruction, and fibrosis leading to cholestasis. In plasma, increased concentrations of IgG, IgM, and AMA autoantibodies (anti-PDC-E2) were detected. Interestingly, the phenotype of Mcpip1AlbKO mice was robust in 6-week-old and 52-week-old mice, but milder in 12-24-week-old mice, suggesting early prenatal origin of the phenotype and age-dependent progression of the disease. Hepatic transcriptome analysis of 6-week-old and 24-week-old Mcpip1AlbKO mice showed 812 and 8 differentially expressed genes (DEGs), respectively, compared with age-matched control mice, and revealed a distinct set of genes compared to those previously associated with development of PBC. ConclusionsThe phenotype of Mcpip1AlbKO mice recapitulates most of the features of human PBC, and demonstrates early prenatal origin and age-dependent progression of PBC. Therefore, Mcpip1AlbKO mice provide a unique model for the study of PBC. Lay summaryDeletion of hepatic Mcpip1 in Mcpip1AlbKO mice leads to development of PBC that recapitulates phenotype of human patients. These animals, show early prenatal origin and age-dependent progression of the disease. Thus, Mcpip1AlbKO mice provide a unique model for studying PBC.

pathology↗