11Beta hydroxysteroid dehydrogenase type 1 is expressed and is biologically active in human skeletal muscle.
OBJECTIVE
No data exist regarding the distribution and oxoreductase enzyme activity of 11beta hydroxysteroid dehydrogenase type 1 (11beta HSD-1) in fresh human skeletal muscle. We aimed to investigate the mRNA and protein expression of 11beta HSD-1 in fresh skeletal muscle, confirm its biological activity and determine its relationship with hexose-6-phosphate dehydrogenase (H6PDH). We also examined the muscle fibre localization of 11beta HSD-1.


METHODS
Eleven non-diabetic community volunteers underwent muscle biopsy of vastus lateralis.


METHODS
(i) 11beta HSD-1 and H6PDH mRNA expression by quantitative reverse transcription polymerase chain reaction (RT-PCR); (ii) protein localization and fibre type specificity by immunohistochemistry; and (iii) enzyme oxoreductase activity by percentage conversion of 3H cortisone to cortisol.


RESULTS
11beta HSD-1 mRNA was expressed at low levels compared to human liver. Mean DeltaCT of skeletal muscle in 11 subjects was 19.57 (range 18.40-20.79) compared to DeltaCT of 12.75 in human liver, which equates to an approximate 100-fold higher level of expression. H6PDH mRNA was also detected with a mean DeltaCT of 14.46 (range 13.13-16.60), approximately 35-fold more abundant than 11beta HSD-1 in skeletal muscle. There was a significant correlation between 11beta HSD-1 and H6PDH (r = 0.67, P = 0.03). 11beta HSD-1 immunostaining was present in all muscle specimens, with similar distribution among fast and slow twitch fibres. 11beta HSD-1 oxoreductase activity was demonstrated, with mean conversion of cortisone to cortisol of 17.7% per 200 mg of muscle per 24 h (range 7.1-29.5%).


CONCLUSIONS
11beta HSD-1 mRNA and protein is expressed in fresh human skeletal muscle along with readily demonstrable oxoreductase activity. 11beta HSD-1 localization is not muscle fibre type specific. High levels of skeletal muscle H6PDH should ensure that oxoreductase activity predominates in vivo.
Jang
Christina
C
Department of Endocrinology and Diabetes, St Vincent's Hospital, Melbourne, Victoria, Australia. christina.jang@svhm.org.au
Obeyesekere
Varuni R
VR
Dilley
Rodney J
RJ
Alford
Frank P
FP
Inder
Warrick J
WJ
D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1 / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000368:Aged; D001681:Biological Assay / Q000379:methods; D003348:Cortisone / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000201:enzymology*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
D012333:RNA, Messenger; D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1; D003348:Cortisone; D006854:Hydrocortisone