The Role Of FKBP51 In Resisting High Fat - Induced Obesity

[Objectives]Steroid hormones are essential to the growth, development, differentiation, and reproduction in mammals. They can regulate gene expression by binding specific steroid receptor as the intracellular signaling transduction and transcription factor. Glucocorticoid receptor (GR) belongs to the steroid receptor superfamily, widely expressed in vivo, and mediated glucocorticoid to regulating the function of behavior and energy metabolism. In recent years, research has shown that GR has great significance in metabolism regulation in vivo.FKBP51 is a TPR-containing immunophilin with peptidyl-prolyl cis-trans isomerase (PPIase) activity. As a cochaperone, FKBP51 can directly bind Hsp90/70 via its respective tetratricopeptide repeat (TPR) domains, and enter into SR complexes at the final stage of assembly. FKBP51 is a negative regulator of SR transcriptional activity, such as Glucocorticoid receptor(GR). Studies point to FKBP51 plays an important role in adipogenesis. In this study we are going to analyze the phenotype of FKBP51 gene knockout mice to study the relationship between FKBP51 and obesity.[Methods] 1) Phenotype analysis. The experiment mice were divided into four groups:NWT (wild type mouse fed with normal diet)、NKO (FKBP51 KO mouse fed with normal diet)、HF WT (wild type mouse fed with hight fat diet)、HF KO (FKBP51 KO mouse fed with hight fat diet). Record the body weight and food intake of the four groups mice from 4-week to 10-week.2) Fat content analysis. Magnetic resonance imaging analysis the HF WT and HF KO mice, and calculate relative area of the fat.3) Histopathological observation in liver. To study the histopathological change in liver, we do paraffin sections stained with hematoxylin and eosin (H&E)% cryosections with oil red O staining and embedding in epon/araldite for electron microscopy of the four group mice.4) Energy metabolism analysis. The energy expenditure (O2 consumption, CO2 production, respiratory exchange ratio, and heat production) of each group was monitored using the MM-100 metabolism cages system for 24 hours.5) RNA sequencing. We extracted RNA of liver tissue in the four group mice NWT, NKO, HFWT and HFKO.Using the second-generation sequencing technology, the samples of RNA sequencing were analysis. We tried to find some genes related to hepatic lipid metabolism according to sequence results.6) Real-time PCR and western blot. This result can further validate the expression of some lipid metabolism and autophagy related genes among the four group mice.7) In vitro Adipocyte differentiation. Induction of adipocyte differentiation of immortalized MEF cells from WT and FKBP51 KO mice were used to observe the effect of FKBP51 gene on lipogenesis in vitro.[Results] 1) Compared to HFWT mice, HFKO mice have less weight increment with no difference on food consumption.2) By magnetic resonance imaging analysis, HFKO mice has less fat accumulation than HF WT mice.3) Histopathological analysis of liver. Compared to HFWT mice, HFKO mice have less lipid accumulation in the liver, and it was also found autophagosome increased in KO mice. The result of real-time PCR and western blot further evaluated the expression of some autophagy related genes.4) By analysis the metabolic cages, FKBP51 KO mice have a high level of energy metabolism compared to WT mice.5) The results of RNAseq showed that lacking of FKBP51 gene might cause some energy metabolism and lipid metabolism related gene expression significantly changed. And the result of real-time PCR and western blot futhur confirmed two lipid metabolism genes,ATPase and LPL upregulated in FKBP51 KO mice.6) From in vitro adipocyte differentiation, we found that FKBP51 KO MEF cells has less lipid droplets compared toWT MEF cells.[Conclusions] 1) FKBP51 gene knock-out mice resistant to high fat diet-induced obesity.2) The liver of FKBP51 gene knock-out mice had few lipid droplet accumulation and autophagosome increased.3) FKBP51 gene knock-out mice had a high level of energy metabolism,and the expression of LPL、UCP-1、ATPase increased.4) Adipocyte differentiation the of FKBP51 gene knock-out mice MEF cells were blocked.