Characterization of 11 beta-HSD1B gene expression and enzymatic activity.
Nuclease protection analysis has been used to study the distribution of an mRNA that has been predicted to give rise to a truncated form of the enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD1B). The 11 beta-HSD1B mRNA was found exclusively in the kidney, predominantly localized within the medulla with low amounts of the message in the cortex. Neither the renal papilla nor a range of peripheral and central tissues showed evidence of 11 beta-HSD1B mRNA. Expression of the whole (11 beta-HSD1A) and truncated enzymes in COS cells resulted in immunoreactive 34 kDa and 26 kDa proteins respectively, while kidney homogenates showed 34 kDa and 40 kDa species. The 11 beta-HSD1A enzyme converted corticosterone and cortisol to their respective 11-dehydro metabolites with an absolute dependence on NADP as co-factor, while the 26 kDa 11 beta-HSD1B protein was unable to metabolize either steroid. These results suggest that transcription of the 11 beta-HSD1B mRNA is associated with a mechanism down-regulating production of 11 beta-HSD1 activity.
Mercer
W
W
Laboratory of Molecular Hypertension, Baker Institute of Medical Research, Melbourne, Australia.
Obeyesekere
V
V
Smith
R
R
Krozowski
Z
Z
D042842:11-beta-Hydroxysteroid Dehydrogenases; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D003345:Corticosterone / Q000378:metabolism; D004247:DNA / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D006854:Hydrocortisone / Q000378:metabolism; D006913:Hydroxysteroid Dehydrogenases / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D007672:Kidney Cortex / Q000201:enzymology; D007679:Kidney Medulla / Q000201:enzymology*; D008970:Molecular Weight; D009249:NADP / Q000378:metabolism; D009928:Organ Specificity; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013379:Substrate Specificity
D007527:Isoenzymes; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D009249:NADP; D004247:DNA; D006913:Hydroxysteroid Dehydrogenases; D042842:11-beta-Hydroxysteroid Dehydrogenases; D003345:Corticosterone; D006854:Hydrocortisone