Proteome Analysis Of Atrophy By Hindlimb Suspension In Rat Skeletal Muscle

Objective:The aim of the work was to identify major proteins responding significantly to the disuse atrophy during hindlimb and reloading in rat skeletal muscle using proteomics analysis. Understanding the molecular mechanism involved in disuse atrophy muscle can provide the scientific basis for clinically preventing and curing disuse muscle atrophy.Methods:We established the model of disuse muscle atrophy by 2-week hindlimb suspension in female SD rats. The total proteins were extracted from the normal(C), the 2-week hindlimb suspension(S) and the 2-week reloading(R) muscle tissues by the TCA/acetone precipitation and direct lysis methods. Protein content was determined by the Bradford protein assay, Then run IEF electrophores as the first dimension, the SDS-PAGE as the second dimension, staining by Coomassie Brilliant Blue and Silver stain. The protein spots were analyzed by PDQuest software to find differences between groups. The differentially expressed proteins were identified preliminary through the reference map in the SWISS-2D PAGE database, combined with a large number of published literatures on protein of rat skeletal muscle maps.Results:1.This study established the proteomic technique system of rat skeletal muscle and provided a matchset for S and R groups.2.Compared with unsuspended controls, S group animals had 25 proteins altered significantly. The levels of contractile proteins decreased such as Tropomyosin alpha, beta chain, myosin regulatory light chain 2, myosin light chain 1, troponinⅠ, desmin, CAPzb protein, while myosin light chain 3 was increased during unloading, all these contractile proteins didn't returned to the control levels in R group. Metabolic proteins increased inα,βenolase, Glycerol 3-P dehydrogenase, Creatine kinase, M chain, ATP-synthase beta chain, mitochondrial precursor, Peroxiredoxin 6, Carbonic anhydrase III in S group, while Triosephosphate isomerase 1 was decreased. The levels of heat shock proteins (Hsp27, p20, Hspβ-6, Alpha crystallinβchain) increased in S group and still increased in R group except Alpha crystallinβchain. The levels of serum albumin, serotransferrin precursor(beta 1 metal binding globulin), DJ-1 protein decreased in S group but returned to control levels in R group.3. These results showed that 2-week hindlimb suspension can cause disuse muscle atrophy significantly, and didn't recovery in 2-week reloading.Discussion:The present study has successfully established 2-DE technology system in rat skeletal muscle. It can prove that 2-DE is a very powerful way to analyze the overall levels of skeletal muscle proteins. In this study, differentially expressed proteins were mainly grouped into different classes including metabolic proteins, contractile proteins, stress proteins, transport proteins. These changes may be the marker of the skeletal muscle disuse atrophy and may be important to the depth study of pathogenesis and pathological physiological processes. In this analysis, however, other classes of proteins such as transcription factors and signal transduction molecules were not detected on 2D-PAGE gels. Thus further analysis would be necessary to analyze these low-abundance proteins to find new features of muscle tissues.