Calpain-10 gene and protein expression in human skeletal muscle: effect of acute lipid-induced insulin resistance and type 2 diabetes.
OBJECTIVE
Our objective was to investigate the effect of lipid-induced insulin resistance and type 2 diabetes on skeletal muscle calpain-10 mRNA and protein levels.


METHODS
In the first part of this study, 10 healthy subjects underwent hyperinsulinemic euglycemic (4.5 mmol/liter) clamps for 6 h with iv infusion of either saline or a 20% Intralipid emulsion (Fresenius Kabi AG, Bad Homburg, Germany). Skeletal muscle biopsies were taken before and after 3- and 6-h insulin infusion and analyzed for calpain-10 mRNA and protein expression. In the second part of the study, muscle samples obtained after an overnight fast in 10 long-standing, sedentary type 2 diabetes patients, 10 sedentary, weight-matched, normoglycemic controls, and 10 age-matched, endurance-trained cyclists were analyzed for calpain-10 mRNA and protein content.


RESULTS
Intralipid infusion in healthy subjects reduced whole body glucose disposal by approximately 50% (P<0.001). Calpain-10 mRNA (P=0.01) but not protein content was reduced after 6-h insulin infusion in both the saline and Intralipid emulsion trials. Skeletal muscle calpain-10 mRNA and protein content did not differ between the type 2 diabetes patients and normoglycemic controls, but there was a strong trend for total calpain-10 protein to be greater in the endurance-trained athletes (P=0.06).


CONCLUSIONS
These data indicate that skeletal muscle calpain-10 expression is not modified by insulin resistance per se and suggest that hyperinsulinemia and exercise training may modulate human skeletal muscle calpain-10 expression.
Norton
L
L
Centre for Integrated Systems Biology and Medicine, School of Biomedical Sciences, Nottingham University, Nottingham, NG7 2UH, United Kingdom.
Parr
T
T
Chokkalingam
K
K
Bardsley
R G
RG
Ye
H
H
Bell
G I
GI
Pelsers
M M A L
MM
van Loon
L J C
LJ
Tsintzas
K
K
D000328:Adult; D002154:Calpain / Q000032:analysis / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D005217:Fat Emulsions, Intravenous / Q000494:pharmacology*; D051275:Glucose Transporter Type 4 / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis
D005217:Fat Emulsions, Intravenous; D051275:Glucose Transporter Type 4; D007328:Insulin; D012333:RNA, Messenger; C495692:SLC2A4 protein, human; D002154:Calpain; C415197:calpain 10