Identification Of Genes Associated With Sarcopenia Based On Bioinformatic Analysis

Objective The aim of this study was to explore the candidate genes related to sarcopenia based on bioinformatics methods,and to provide a theoretical basis for the study of the pathogenesis of sarcopenia.Methods The sarcopenia-related data sets GSE1428 and GSE8479 were downloaded from the Gene Expression Omnibus database.The gene names were extracted using R language,and the two datasets were merged using Perl software.The"limma"package of R was used for batch correction and screening for differentially expressed genes(DEGs)between skeletal muscle of elderly patients with sarcopenia and that of young adults.Gene ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes pathway were analyzed using the DAVID online tool.The STRING database were used to analyze the interaction of differentially encoded proteins and the protein interactions were visualized using Cytoscape software.The"Cytohubba"plug-in was used to select the hub genes by the node degree and stress.The diagnostic effect of each hub gene was evaluated using receiver operating characteristic curve.Muscle specimens were collected from young and elderly patients without and with sarcopenia undergoing the spinal surgery.Then,we used q PCR to perform a preliminary validation of these hub genes.Results1.DEGs were defined as genes log₂ fold change(log|FC|)>0.5,and adjusted P value<0.05.A total of 121 DEGs were screened out,including 69 up-regulated genes and 52down-regulated genes.The top six DEGs with the highest log|FC|value were SLPI(log FC=1.233),MYH8(log FC=1.079),CDKN1A(log FC=1.075),GADD45G(log FC=-1.190),SLC38A1(log FC=-1.168),and HOXB2(log FC=-1.079,all P<0.001).2.Gene ontology was mainly associated with terms such as cell growth regulation,response to peptide hormones,response to mechanical stimuli and senescence.Kyoto genes and genomic encyclopedia pathways were mainly enriched in six pathways such as glycolysis/glycogenesis and p53 signaling pathway.3.A total of nine hub genes,including CDKN1A,LDHA,TPI1,LUM,ACTA2,CYCS,MYH11,TIMP1 and CTGF,were derived by protein interaction network module analysis.Among them,TPI1 and LDHA were localized in the glycolysis/gluconeogenesis,and CYCS and CDKN1A were localized in the p53 signaling pathway.4.Receiver operating characteristic curve showed that the efficacy of each hub gene was evaluated in the order of HOXB2,CDKN1A,SLPI,TPI1,SLC38A1,LDHA,MYH8,GADD45G and CYCS.5.The results of real-time quantitative PCR of muscle tissue showed that HOXB2mRNA expression was significantly decreased in both male and female elderly patients with sarcopenia compared to those young patients without sarcopenia(P<0.05).In addition,TPI1 mRNA expression was decreased in male patients(P<0.05)and MYH8mRNA expression was increased in male patients(P<0.05).TPI1 mRNA expression was downregulated by 48%in male patients with sarcopenia compared to elderly controls without sarcopenia(P=0.008).The trends of TPI1 mRNA and MYH8 mRNA in the female sarcopenia group were the same as those in males,but the differences were not statistically significant.Conclusion There are gender differences in the expression of pathogenic genes associated with sarcopenia.HOXB2,TPI1 and the glycolytic/gluconeogenic signaling pathway may be the key components of the pathogenesis of sarcopenia.MYH8 is expected to serve as a new marker of male sarcopenia.