The Mechanism Of MPC1 On Energy Metabolism

MPC,which is called mitochondrial pyruvate carrier,is a complex protein located in mammalian mitochondrial membrane.It consists of two subunits,MPC1 and MPC2.This protein is mainly responsible for transporting pyruvate from the cytosolic glycolysis into the mitochondrial matrix and plays an important role in the energy metabolism.Since the lack of MPC1 and MPC2 leads to embryonic lethality,it is impossible to generate homozygous gene knockout mouse model.Heterozygous or tissue-specific knockout animal models are usually used in research.In this study,one mpc1 knockdown mouse model was generated by CRISPR/Cas9 technology.By studying the changes of energy metabolism phenotype in this model,and using Omics,qPCR and Western blot techniques to explore the molecular regulation mechanism of energy compensation after MPC1 injury,we provide a scientific basis for further exploration of the role of MPC1 in energy metabolism.(1)An ideal mouse model that can be stably inherited was successfully constructed by CRISPR/Cas9 technology.Western blot analysis showed that the expression of MPC1 protein in MPC1+/-mouse was significantly reduced by 60%.(2)The MPC1+/-mice were subjected to a 24-week feeding experiment.The energy metabolism phenotype study showed that MPC1+/-mice presented reduced body weight,activity,gluconeogenesis and fat accumulation.In the case of fasting and cold stimulation,the brown adipose tissue activity of MPC1+/-mice was decreased and the lipid degradation ability was enhanced.After administration of a high-fat diet,VPC1+/-mice returned to the metabolic level of normal mice.The results indicated that in order to compensate for the lack of energy metabolism caused by MPC1 deficiency,MPC1+/-mice utilized fatty substances instead of carbohydrates to provide energy.(3)The liver is an important organ for glycolipid metabolism in the body.To further explore the molecular mechanisms of changes in the energy metabolism in the liver of MPC1+/-mice,proteomics and transcriptomics analysis were performed on the liver.The trend of energy metabolism pathway revealed by the two omics results was consistent.The lipid oxidative degradation ability of MPC11+/-mice was enhanced,and the ability of lipid synthesis and differentiation was weakened.This result further confirmed the finding in the phenotypic study.(4)Phenotypic studies found a significant reduction in fat accumulation in MPC1+/-mice.The white adipose tissue and brown adipose tissue were further selected for transcriptomic analysis.The results showed the same trend in energy metabolism of the two types of adipose tissue in transcriptomics,which was mainly manifested by the enhanced lipid oxidizing ability and weakened synthesis and differentiation ability of MPC1+/-mice.This result is consistent with the results of omic analysis of liver tissue.(5)This study explored the molecular mechanism of energy regulation in MPC1+/-mice by qPCR and Western-blot methods.When the actiAity of MPC1 protein is decreased,the expression of enzymes involved in fat synthesis such as ATP citrate lyase(ALCY),fatty acid synthase(FASN)and acetyl-CoA carboxylase(ACC)were down-regulated and the lipid synthesis and fat accumulation were reduced by inhibiting PPAR? and C/EBPs signaling pathways.By activating the PPARa signaling pathway,the expression of fatty triglyceride lipase(ATGL),hormone-sensitive esterase(HSL)and perilipines was increased to promote fat catabolism.In this study,the MPC1 whole-body knockdown mouse model was generated by CRISPR/Cas9 system,and the effect of MPC1 deficiency on the energy metabolism of the body was studied.The results showed that MPC1+/-mice used an alternative way to the carbohydrates metabolism to supply energy by reducing body fat accumulation and enhancing fatty acid metabolism.This study provides a new theoretical basis for further exploration of the physiological functions of MPC1,and also provides new ideas and targets for the treatment of cancer and other chronic metabolic diseases.