FKBP51 Null Mice Resist To Diet-Induced Obesity By Increasing Mitocphagy

[Objectives]Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health,such as diabetes,cardiovascular disease,cancers and so on.As a member of the immunophilin family of proteins,the FK506-binding protein 51(FKBP51)is rapidly emerging as an important regulator of immunity,steroidal physiology,and basic cellular processes of protein folding and trafficking.Our previous studies found that in FKBP51 knockout mice the synthesis of adipocyte was blocked,and the mice with high-fat diets resist fat accumulation.Based on the successful establishment of high-fat diet induced model,in this study we will explore the role of FKBP51 in lipid metabolism,and wish to find the new targets for preventing obesity.[Methods]The four-week-old mice were divided into the following four groups according to their genotypes:normal diet wild male(RD WT),high-fat diet wild male(HF WT),normal diet FKBP51-knockout male(RD KO),and high-fat diet FKBP51-knockout males(HF KO),6 mice per group.1)Measurement of body weights:The initial body weight of the mice was weighed before grouping,and the body weight of the mice was measured once a week from forth week to tenth week.2)The glucose metabolism in FKBP51 WT and KO mice under high-fat diet was measured by PET-CT.3)The total mRNA from livers of high-fat diet treated or regular diet treated animal was extracted and sequenced using the next generation sequencing technique approach in BGI.Genes which were differentially expressed between KO and WT were analyzed with the functional annotation tool of the DAVID bioinformatics resources 6.7(http://david.abcc.ncifcrf.gov).4)The mRNA expression of GCK,Cyp21al,Cyp4a10,and Cyp4a14 were detected using the real-time PCR.5)The mitochondria morphology was observed by electron microscopy,and the mitochondrial size was measured by NIH-ImageJ software.6)The expression of autophagy and mitochondrial autophagy-related genes were detect by western blot.7)Using Co-IP experiment,the interaction between FKBP51 and Parkin was performed.8)Detection of Parkin changes by interference and overexpression of FKBP51 gene in cell lines.[Results]1)Statistical analysis of weekly weight changes in mice revealed that under high-fat diet conditions,the body weight of HF KO mice was significantly lower than that of HF WT mice;2)PET-CT results showed the level of glucose metabolism is high in FKBP51 KO mice in vivo;3)RNA-seq analysis results show that:Knockout of FKBP51 mainly leads to changes in gene expression related to metabolic processes in the liver;4)Detection of relevant molecular pathways of metabolic pathways by Real-time PCR,found the expression level of GCK was significantly higher in RD KO group than that of RD WT group.The expression levels of Cyp21a1,Cyp4al0,and Cyp4a14 were significantly lower than those of RD WT group.These results showed that when the FKBP51 gene was knocked out,the metabolic levels of the mice increased;5)The mitochondrial deformation,enlarged or even ruptured destruction was observed in HF WTgroup observed by transmission electron microscopy,but mitochondrial damage was not obvious in HF KO mice;Mitochondrial area measurements showed that liver mitochondria of the KO group was greater than those of the WT group;Further study found the mitochondrial autophagy in the HF KO mice has become more severe than that in the HF WT observed by high magnification electron microscope;6)Western blot results showed that the expression of autophagy and mitophagy related proteins were higher in FKBP51 KO group than WT group;7)Co-IP experiments showed that there was a direct interaction between FKBP51 and Parkin in protein level;8)Downregulation FKBP51 cause Parkin increased in SY5Y cell lines,upregulation FKBP51 cause Parkin decreased in H293 cell lines.[Conclusions]In FKBP51 knockout male mice,deletion of the FKBP51 gene affectes the expression of metabolically related genes,altered the size of the mitochondria and the level of autophagy in the liver,and thus resisted high-fat-induced obesity.