TY - JOUR
T1 - Mutants of 11-hydroxysteroid dehydrogenase (11-hsd2) with partial activity
T2 - Improved correlations between genotype and biochemical phenotype in apparent mineralocorticoid excess
AU - Nunez, B. Scott
AU - Rogerson, Fraser M.
AU - Mune, Tomoatsu
AU - Igarashi, Yoshio
AU - Nakagawa, Yuichi
AU - Phillipov, George
AU - Moudgil, Asha
AU - Travis, Luther B.
AU - Palermo, Mario
AU - Shackleton, Cedric
AU - White, Perrin C.
PY - 1999/10
Y1 - 1999/10
N2 - Mutations in the kidney isozyme of human 11-hydroxysteroid dehydrogenase (11-HSD2) cause apparent mineralocorticoid excess, an autosomal recessive form of familial hypertension. We studied 4 patients with AME, identifying 4 novel and 3 previously reported mutations in the HSD11B2 (HSD11K) gene. Point mutations causing amino acid substitutions were introduced into a pCMV5/11HSD2 expression construct and expressed in mammalian CHOP cells. Mutations L179R and R208H abolished activity in whole cells. Mutants S180F, A237V, and A328V had 19%, 72%, and 25%, respectively, of the activity of the wild-type enzyme in whole cells when cortisol was used as the substrate and 80%, 140%, and 55%, respectively, of wild-type activity when corticosterone was used as the substrate. However, these mutant proteins were only 0.6% to 5.7% as active as the wild-type enzyme in cell lysates, suggesting that these mutations alter stability of the enzyme. In regression analyses of all AME patients with published genotypes, several biochemical and clinical parameters were highly correlated with mutant enzymatic activity, demonstrated in whole cells, when cortisol was used as the substrate. These included the ratio of urinary cortisone to cortisol metabolites (R2=0.648, P<0.0001), age at presentation (R2=0.614, P<0.0001), and birth weight (R2=0.576, P=0.0004). Approximately 5% conversion of cortisol to cortisone is predicted in subjects with mutations that completely inactivate HSD11B2, suggesting that a low level of enzymatic activity is mediated by another enzyme, possibly 11-HSD1.
AB - Mutations in the kidney isozyme of human 11-hydroxysteroid dehydrogenase (11-HSD2) cause apparent mineralocorticoid excess, an autosomal recessive form of familial hypertension. We studied 4 patients with AME, identifying 4 novel and 3 previously reported mutations in the HSD11B2 (HSD11K) gene. Point mutations causing amino acid substitutions were introduced into a pCMV5/11HSD2 expression construct and expressed in mammalian CHOP cells. Mutations L179R and R208H abolished activity in whole cells. Mutants S180F, A237V, and A328V had 19%, 72%, and 25%, respectively, of the activity of the wild-type enzyme in whole cells when cortisol was used as the substrate and 80%, 140%, and 55%, respectively, of wild-type activity when corticosterone was used as the substrate. However, these mutant proteins were only 0.6% to 5.7% as active as the wild-type enzyme in cell lysates, suggesting that these mutations alter stability of the enzyme. In regression analyses of all AME patients with published genotypes, several biochemical and clinical parameters were highly correlated with mutant enzymatic activity, demonstrated in whole cells, when cortisol was used as the substrate. These included the ratio of urinary cortisone to cortisol metabolites (R2=0.648, P<0.0001), age at presentation (R2=0.614, P<0.0001), and birth weight (R2=0.576, P=0.0004). Approximately 5% conversion of cortisol to cortisone is predicted in subjects with mutations that completely inactivate HSD11B2, suggesting that a low level of enzymatic activity is mediated by another enzyme, possibly 11-HSD1.
KW - Hydrocortisone
KW - Hydroxysteroid dehydrogenases
KW - Hypertension
KW - Metabolism
KW - Mineralocorticoids
KW - Mutation
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U2 - 10.1161/01.HYP.34.4.638
DO - 10.1161/01.HYP.34.4.638
M3 - Article
C2 - 10523339
AN - SCOPUS:0033211082
SN - 0194-911X
VL - 34
SP - 638
EP - 642
JO - Hypertension
JF - Hypertension
IS - 4
ER -