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Critical Reviews™ in Eukaryotic Gene Expression
Fator do impacto: 1.841 FI de cinco anos: 1.927 SJR: 0.649 SNIP: 0.516 CiteScore™: 1.96

ISSN Imprimir: 1045-4403
ISSN On-line: 2162-6502

Critical Reviews™ in Eukaryotic Gene Expression

DOI: 10.1615/CritRevEukarGeneExpr.v5.i2.30
pages 157-176

Androgen Action

Arun K. Roy
Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78284
Bandana Chatterjee
Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78284

RESUMO

Androgens are C-19 steroids that provide major regulatory influences on male reproductive function. Testosterone, the principal androgenic steroid, is secreted by the Leydig cells of the testes. Both testosterone and its 5α reduced derivative 5α-dihydrotestosterone (DHT) are physiological ligands for the androgen receptor (AR). Ligand-activated AR acts as a nuclear transcription factor and mediates androgen action. AR, along with receptors for a number of C-21 steroids such as glucocorticoid, mineralocorticoid, and progesterone, share the same 15 base pair consensus element composed of 5’-GGA/TACAnnnTGTTCT-3’. Despite this cross-reactivity at the level of the DNA, physiologically, androgens regulate their target genes with a high degree of receptor specificity. Such a regulatory specificity appears to be due to multiphasic interactions involving enzymatic activation/inactivation of the steroid ligand, interaction with specific receptor-associated nuclear factors on or around the hormone response element, and differential regulation of the receptor gene expression. Conversion of testosterone to 5α-dihydrotestosterone in target cells is a widespread activation mechanism that amplifies the androgenic signal. Unlike the testosterone-AR complex, DHT-activated AR has a longer half-life, and thus prolongs androgen action. Oxido-reduction of androgens by 17β-hydroxysteroid dehydrogenase and sulfurylation by androgen sulfotransferase are two major pathways of androgen inactivation in target cells. Prenatal deprivation of androgen action, due to mutations in either the AR or the 5α-reductase gene, results in developmental abnormalities of male reproductive tissues and also cause partial or complete androgen-insensitivity syndromes. Elucidation of various molecular steps in androgen action is allowing development of improved therapeutic agents for the management of disorders of androgen action such as the prostatic hypertrophy and neoplasia.


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