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Research Article Free access | 10.1172/JCI116665

Tissue distribution and ontogeny of steroid 5 alpha-reductase isozyme expression.

A E Thigpen, R I Silver, J M Guileyardo, M L Casey, J D McConnell, and D W Russell

Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.

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Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.

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Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.

Find articles by Guileyardo, J. in: JCI | PubMed | Google Scholar

Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.

Find articles by Casey, M. in: JCI | PubMed | Google Scholar

Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.

Find articles by McConnell, J. in: JCI | PubMed | Google Scholar

Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas 75235.

Find articles by Russell, D. in: JCI | PubMed | Google Scholar

Published August 1, 1993 - More info

Published in Volume 92, Issue 2 on August 1, 1993
J Clin Invest. 1993;92(2):903–910. https://doi.org/10.1172/JCI116665.
© 1993 The American Society for Clinical Investigation
Published August 1, 1993 - Version history
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Abstract

The synthesis of dihydrotestosterone is catalyzed by steroid 5 alpha-reductase isozymes, designated types 1 and 2. Mutation of type 2 results in male pseudohermaphroditism, in which the external genitalia are phenotypically female at birth. Two striking and unexplained features of this disorder are that external genitalia of affected males undergo virilization during puberty and that these individuals have less temporal hair regression. The tissue-specific and developmental expression patterns of the 5 alpha-reductase isozymes were investigated by immunoblotting. The type 1 isozyme is not detectable in the fetus, is transiently expressed in newborn skin and scalp, and permanently expressed in skin from the time of puberty. There was no qualitative difference in 5 alpha-reductase type 1 expression between adult balding vs. nonbalding scalp. The type 2 isozyme is transiently expressed in skin and scalp of newborns. Type 2 is the predominant isozyme detectable in fetal genital skin, male accessory sex glands, and in the prostate, including benign prostatic hyperplasia and prostate adenocarcinoma tissues. Both isozymes are expressed in the liver, but only after birth. These results are consistent with 5 alpha-reductase type 1 being responsible for virilization in type 2-deficient subjects during puberty, and suggest that the type 2 isozyme may be an initiating factor in development of male pattern baldness.

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