Study On The Effects And Mechanism Of Liver ZNRF3/RNF43 In Regulating Energy Metabolism

The liver is a key organ involved in the energy metabolism in the body.Besides,liver,as a secretory organ,can secrete hepatokines and regulate metabolism of other tissues through paracrine or endocrine pathways,and then influence systemic energy metabolism.ZNRF3(zinc and ring finger 3)and RNF43(ring finger protein 43)belong to the single transmembrane E3 ubiquitin ligase family,containing a signal peptide,an extracellular domain,a transmembrane domain and an intracellular ring domain.ZNRF3/RNF43 can induce ubiquitination degradation of Wnt signaling pathway receptor,and negatively regulate the Wnt signaling pathway.Wnt signaling pathway is closely related to energy metabolism.Since ZNRF3 and RNF43 are highly homologous in structure and similar in function,they have similar impact on the Wnt signaling pathway.Importantly,we need to investigate ZNRF3 and RNF43 together because they will compensate the other if one of them is knocked out.The goal of this study is to elucidate the regulatory effects of ZNRF3/RNF43 on glucose and lipid metabolism.We knock out liver ZNRF3/RNF43 gene by using the lox P-cre recombinant enzyme system.In our research,we found that ZNRF3/RNF43 double knockout could reduce the weight,increase the body temperature and increase the basal metabolic rate of mice.Through the glucose tolerance test and serum insulin,liver triglyceride measurement,we also found ZNRF3/RNF43 double knockout could improve liver insulin resistance,inhibit gluconeogenesis,reduce liver lipid deposition and reduce inflammation.In addition,we detected the content of adipose tissue and analyzed some protein and gene related to energy metabolism,and found that ZNRF3/RNF43 double-knockout mice can reduce the lipid synthesis,reduce the inflammation of adipose tissue,and induce WAT browning.Finally,metabolomics and genomic sequence analysis suggested that ZNRF3/RNF43 may affect metabolites and the expression of hepatokines.In summary,our research found that ZNRF3/RNF43 double knockout can improve systemic insulin resistance by regulating metabolites and hepatokines,reducing lipid synthesis,promoting browning to increase energy consumption,and provide new clues for the treatment of obesity and type 2 diabetes.On the other hand,obesity leads to lipid metabolism disorder and ectopic lipid deposition.We use db/db obese mice and C2C12 cells to explore the effects of berberine on skeletal muscle ectopic lipid deposition and skeletal muscle cell mitochondrial function.The experimental results showed that berberine could reduce the content of triglyceride in skeletal muscle,increase the number of mitochondria in skeletal muscle cells,and enhance the function of mitochondria.Besides berberine can promote the expression of transcription factor PGC1 a through AMPK pathway.In addition,berberine could increase the maximum oxygen consumption rate of C2C12 cells,indicating that berberine could enhance the mitochondrial oxidation function.Our research proved that berberine can reduce ectopic lipid deposition in skeletal muscle,enhance mitochondrial function,and improve basal metabolic rate.