Study On The Regulation Mechanism Of Gsc On Preadipocyte Differentiation And Its Expression Difference In Adipose Tissue Of Obese People

Obesity is the result of excess energy due to diet,exercise and genetic predisposition.Adipose tissue is a highly plastic organ and plays a key role in regulating energy metabolism throughout the body.In the case of chronic overnutrition,adipose tissue expands by increasing adipocyte size(hypertrophy)and/or adipocyte number(hyperplasia).Adipocyte hypertrophy causes fibrosis and inflammation,which promotes metabolic disease.Proliferative growth,mediated by the differentiation of progenitor cells into new adipocytes,is crucial for maintaining adipose tissue function and preventing metabolic diseases.Currently,the mechanisms controlling healthy adipose tissue expansion and obesity-driven metabolic syndrome remain poorly understood.Therefore,it is important to establish the lineage of adipose progenitor cells and study the regulation of adipose differentiation to comprehensively understand the normal or abnormal biological functions of adipocytes.This study consists of two parts.Part I The effect of Gsc on the differentiation of adipose progenitor cells in miceObjective:sc RNA-seq was used to identify multiple cell types of mouse adipose stromal vascular fraction and identify specific subtypes with high differentiation potential.To find the transcription factor with high expression in this subtype,and explore the mechanism of the transcription factor on preadipocyte differentiation.Methods:Epididymal white adipose tissue(eWAT)and inguinal white adipose tissue(i WAT)and brown adipose tissue of interscapular(BAT)were isolated from SVF by collagenase digestion,and then the precipitated cells were analyzed by Drop-seq.Highthroughput single-cell transcriptome studies and unsupervised clustering of gene expression profiles identified different subtypes of adipocytes.The "Find Marker" was used to select the top 200 highly expressed genes without bias,and then the top genes were classified according to the gene family to find the target gene Gsc.To investigate the possible mechanism of the effect on adipose differentiation in mice by detecting Gsc expression level under physiological state,reference transcriptome sequencing analysis,transcription and protein expression.Results:There were 20 different subtypes of adipocyte progenitor cells.Genes related to adipocyte differentiation were highly expressed in specific subtypes,mainly concentrated in Cluster 11,and Gsc was highly expressed in Cluster 11.Compared with mice on a normal diet,the expression level of Gsc in white adipose tissue of mice fasted for 48 hours decreased significantly.Cold stimulation inhibited Gsc expression in white adipose tissue of mice.The expression level of Gsc in white adipose tissue of mice was significantly increased by short-term high-fat diet,while the expression level of Gsc was significantly inhibited by long-term high-fat diet.A total of 332 differentially expressed genes,including 144 up-regulated genes and 188 downregulated genes,were found between Gsc overexpressed samples and control samples by reference transcriptome study.Through GO analysis,it can be seen that differential genes after Gsc overexpression are mainly enriched in development,cell differentiation and other related functions.KEGG analysis showed that the differential genes were mainly enriched in insulin signaling pathway and insulin resistance pathway.GSEA analysis of differential genes mainly focused on mitochondrial translation and respiratory chain electron transfer pathway.The level of phosphorylated SDHB subunit protein increased.During SVF differentiation,Gsc expression level was higher in adipocyte progenitor cells and lower in mature adipocytes.Conclusions:Through single-cell transcriptome studies,we identified an unknown transcription factor Gsc that may influence adipose differentiation.The expression level of Gsc in physiological state was significantly correlated with promoting or inhibiting adipogenesis.After Gsc overexpression,mitochondrial translation,oxidative phosphorylation and electron transport phase genes in respiratory chain are upregulated,which may be the key factors promoting adipose differentiation.obese people and its correlation with clinical indicators Part II The expression level of GSC in adipocytes ofObjective:To investigate the expression level of GSC in visceral adipose tissue and subcutaneous adipose tissue of obese people and its correlation with clinical indicators.Methods:This study was a cross-sectional study.Gender,age,physical examination,and laboratory examination,were collected from patients who underwent laparoscopic sleeve gastrectomy in the department of metabolic surgery for bariatric diabetes in Shanghai Tenth People’s Hospital from February 2019 to October 2020.The indications and contraindications for surgery were evaluated according to the Chinese Guidelines for the Surgical Treatment of Obesity and Type 2 Diabetes,and the patients’ informed consent was obtained.Subcutaneous and visceral adipose tissues were collected under general anesthesia during surgery.RNA was extracted from adipose tissue and the relative expression level of GSC m RNA was detected by real-time fluorescence quantitative PCR.The expression of GSC in visceral adipose tissue and subcutaneous adipose tissue and its correlation with clinical indicators were analyzed.Results:A total of 62 obese patients were included in the study,including 19 males and 43 females,aged 16-64 years,with an average BMI of 39.55±6.10kg/m2.There were no significant differences between men and women in age,BMI or fat content,but women had larger waist and hip circumference than men.Men had higher levels of blood pressure,triglycerides,fasting insulin,uric acid,alanine aminotransferase and aspartate aminotransferase than women.The expression level of GSC in visceral adipose tissue was higher than that in subcutaneous adipose tissue.When HOMA-IR was less than 8,there was no difference in GSC expression between subcutaneous adipose tissue and visceral adipose tissue.However,when HOMA-IR was greater than 8,GSC expression level in visceral adipose tissue was higher than that in subcutaneous adipose tissue.There was no difference in GSC expression between subcutaneous adipose tissue and visceral adipose tissue in the non-acanthosis nigricans group(NAN),while GSC expression in visceral adipose tissue was higher than that in subcutaneous adipose tissue in the acanthosis nigricans group(AN).In subcutaneous adipose tissue,GSC was associated with neck circumference(r =0.468,p =0.024),waist circumference(r =0.564,p=0.005),total cholesterol(r =0.415,p =0.025),low density lipoprotein cholesterol(r =0.371,p =0.047),free fatty acids(r =0.429,p=0.029).In visceral adipose tissue,GSC was correlated with waist circumference(r=-0.555,p =0.006),triglyceride(r=0.539,P =0.003)and HOMA-IR(r=0.683,P =0.048).No significant correlation was observed for other metabolic indicators.Conclusion: GSC expression level is different in visceral adipose tissue and subcutaneous adipose tissue,and the difference is more obvious in insulin resistance.GSC was correlated with waist circumference,lipid metabolism and HOMA-IR.