Study On The Molecular Mechanism Of Metabolic Disorders Induced By Pathogenic Mutations In LPL Using A Knock-in Mouse Model

OBJECTIVE: A LPL mutant gene was discovered in the earlier stage of this research group.It is intended to study the relationship between the mutant genotype and phenotype at the animal level,and conduct in-depth research on the molecular mechanisms involved in the pathogenesis.Providing accurate diagnosis also provides a strong basis for the development of targeted gene therapy drugs.Methods: The mouse tissues were extracted for DNA detection and genotypes were identified by one-generation sequencing.The wild-type and mutant mice were distinguished and grouped for feeding.By taking the mouse serum,the basal glucolipid metabolism index was measured.IPGTT was used to observe the expression of glucose tolerance in mice.The effect of mutation on the expression of bip and Akt in myocardium and liver tissue was detected by western blot.The effect of mutation on the ultrastructure of myocardium and skeletal muscle was observed by TEM.Results: Genotypes of mice were identified by one-generation sequencing,and wild-type and mutant mice were obtained.Compared with wild-type mice,there was no significant change in serum lipid metabolism in the mutant mice,but there were differences in glucose metabolism.The serum insulin level in the mutant group was significantly higher,and the mice in the IPGTT mutant group had faster blood glucose elevation and higher peak values.At the same time,we observed significant lipid deposition in the liver by oil red o staining.By western blot,it was found that compared with the wild-type mouse,the marked protein bip of endoplasmic reticulum stress in mice with myocardial mutation was significantly increased,but there was no significant difference in bip expression between the two groups of mice in the liver.This indicates that endoplasmic reticulum stress has occurred in the mutant group.In addition,in the myocardial tissue,the phosphorylated Akt levels in the mutant mice were significantly lower than those in the control mice,but there was no significant difference in the total Akt levels between the two groups.Indicates the occurrence of insulin resistance.Electron microscopy showed changes in mitochondria in the myocardium and skeletal muscles.CONCLUSIONS: We used the LPL mutant gene knock-in model to find that the LPL C310 R mutation resulted in significant glucose tolerance abnormalities,and that significant lipid deposition in the liver occurred,which may be the main reason leading to impaired glucose tolerance.At the same time,we found that LPL mutations caused myocardial endoplasmic reticulum stress and insulin resistance,exacerbated abnormal myocardial metabolism,LPL mutations may produce protein toxicity,resulting in endoplasmic reticulum stress and insulin resistance,and then affecting the entire body glucose and lipid metabolism disorder.