Differential Expression Analysis Of Fast And Slow Skeletal Muscles

Skeletal muscle can be categorized into two muscle fiber types:fast muscle and slow muscle, which differ largely in their structure and function. In this study, differential gene expression between fast muscle (longissimus dorsi) and slow muscle (soleus) was detected using pig mRNA expression profile chip of Affymetrix AFF-900623, in order to further understand the molecular mechanism underlying the difference of two muscle fiber types. The pig microarray contains 23937 probe sets representing 20201 genes. The longissimus dorsi and soleus were sampled from three 5-month-old Meishan gilts, respectively. Total cDNA of three longissimus dorsi and three soleus samples was used to hybridize with six gene chips, and the data were analyzed using Genespring 10.0. The results showed that 550 differential expressed transcripts were identified between longissimus dorsi and soleus with fold change of at least 1.5 and p value of<0.05. Of 550 differentially expressed transcripts, the 323 transcripts were up-regulated expression in soleus and 227 up-regulated in longissimus dorsi. The fold changes of 159 transcripts are greater than 2 with the significance of p<0.05, with 107 up-regulated and 52 down-regulated in soleus. Twelve genes (a-Actin, ART3, FHL1C, GATA-6, HMOX1, HSP, MYBPH, OCA2, SLC12A4, TGFβ1, TGFβ3 and TNX) were selceted and validated using quantitative real time polymerase chain reaction (QRT-PCR) to detect the reliability of the results of gene chips. The mRNA expression tendency of 12 genes in QRT-PCR and gene chips was same and their correlations were significant, indicating that the results of gene chips are credible. Pathway, gene ontology, gene correlation and transcription factor analysis of 550 differential expressed genes were conducted using MAS 3.0 and these results laid the basis for the subsequent functional researches.