Expression of endoplasmic reticulum stress proteins during skeletal muscle disuse atrophy.
Disuse atrophy of skeletal muscle leads to an upregulation of genes encoding sarcoplasmic reticulum (SR) calcium-handling proteins. Because many of the proteins that are induced with endoplasmic reticulum (ER) stress are ER calcium-handling proteins, we sought to determine whether soleus muscle atrophy was associated with a prototypical ER stress response. Seven days of rat hindlimb unloading did not alter expression of ubiquitous ER stress proteins such as Grp78, calreticulin, and CHOP/GADD-153, nor other proteins that have been shown to be activated by ER stressors such as vinculin, the type I D-myo-inositol 1,4,5-trisphosphate receptor, or protein kinase R, a eukaryotic initiation factor 2 alpha kinase. On the other hand, expression of heme oxygenase-1 (HO-1), an antioxidant ER stress protein, was significantly increased 2.2-fold. In addition, unloading led to an increase in calsequestrin, the muscle-specific SR calcium-binding protein, at both the mRNA (68%) and protein (24%) levels. Although disuse atrophy is associated with a significant remodeling of muscle-specific proteins controlling SR calcium flux, it is not characterized by a prototypical ER stress response. However, the upregulation of HO-1 may indicate ER adaptation to oxidative stress during muscle unloading.
Hunter
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RB
Department of Health Sciences, Boston University, Boston, Massachusetts 02215, USA.
Mitchell-Felton
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H
Essig
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DA
Kandarian
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SC
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001284:Atrophy; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D037282:Calreticulin; D002155:Calsequestrin / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism; D051547:Heme Oxygenase-1; D007103:Immobilization; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000473:pathology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D016596:Vinculin / Q000235:genetics / Q000378:metabolism; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism
D000975:Antioxidants; D022762:CCAAT-Enhancer-Binding Proteins; D002135:Calcium-Binding Proteins; D037282:Calreticulin; D002155:Calsequestrin; D002352:Carrier Proteins; C497251:Ddit3 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D014157:Transcription Factors; D016596:Vinculin; D051742:Transcription Factor CHOP; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D019892:eIF-2 Kinase