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Journal ArticleDOI

Male pseudohermaphroditism caused by mutations of testicular 17β-hydroxysteroid dehydrogenase 3

TL;DR: Four substitution and two splice junction mutations were identified in the 17βHSD3 genes of five unrelated male pseudohermaphrodites that severely compromised the activity of the 17 β–HSD type 3 isozyme.
Abstract: Defects in the conversion of androstenedione to testosterone in the fetal testes by the enzyme 17β–hydroxysteroid dehydrogenase (17β–HSD) give rise to genetic males with female external genitalia. We have used expression cloning to isolate cDNAs encoding a microsomal 17β–HSD type 3 isozyme that shares 23% sequence identity with other 1 7β–HSD enzymes, uses NADPH as a cofactor, and is expressed predominantly in the testes. The 17βHSD3 gene on chromosome 9q22 contains 11 exons. Four substitution and two splice junction mutations were identified in the 17βHSD3 genes of five unrelated male pseudohermaphrodites. The substitution mutations severely compromised the activity of the 17β–HSD type 3 isozyme.
Citations
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Journal ArticleDOI
TL;DR: Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.
Abstract: Steroidogenesis entails processes by which cholesterol is converted to biologically active steroid hormones. Whereas most endocrine texts discuss adrenal, ovarian, testicular, placental, and other steroidogenic processes in a gland-specific fashion, steroidogenesis is better understood as a single process that is repeated in each gland with cell-type-specific variations on a single theme. Thus, understanding steroidogenesis is rooted in an understanding of the biochemistry of the various steroidogenic enzymes and cofactors and the genes that encode them. The first and rate-limiting step in steroidogenesis is the conversion of cholesterol to pregnenolone by a single enzyme, P450scc (CYP11A1), but this enzymatically complex step is subject to multiple regulatory mechanisms, yielding finely tuned quantitative regulation. Qualitative regulation determining the type of steroid to be produced is mediated by many enzymes and cofactors. Steroidogenic enzymes fall into two groups: cytochrome P450 enzymes and hydroxysteroid dehydrogenases. A cytochrome P450 may be either type 1 (in mitochondria) or type 2 (in endoplasmic reticulum), and a hydroxysteroid dehydrogenase may belong to either the aldo-keto reductase or short-chain dehydrogenase/reductase families. The activities of these enzymes are modulated by posttranslational modifications and by cofactors, especially electron-donating redox partners. The elucidation of the precise roles of these various enzymes and cofactors has been greatly facilitated by identifying the genetic bases of rare disorders of steroidogenesis. Some enzymes not principally involved in steroidogenesis may also catalyze extraglandular steroidogenesis, modulating the phenotype expected to result from some mutations. Understanding steroidogenesis is of fundamental importance to understanding disorders of sexual differentiation, reproduction, fertility, hypertension, obesity, and physiological homeostasis.

1,665 citations

Journal ArticleDOI
TL;DR: This review presents a detailed description of the enzymes involved in the biosynthesis of active steroid hormones, with emphasis on the human and mouse enzymes and their expression in gonads, adrenal glands, and placenta.
Abstract: Significant advances have taken place in our knowledge of the enzymes involved in steroid hormone biosynthesis since the last comprehensive review in 1988. Major developments include the cloning, identification, and characterization of multiple isoforms of 3β-hydroxysteroid dehydrogenase, which play a critical role in the biosynthesis of all steroid hormones and 17β-hydroxysteroid dehydrogenase where specific isoforms are essential for the final step in active steroid hormone biosynthesis. Advances have taken place in our understanding of the unique manner that determines tissue-specific expression of P450aromatase through the utilization of alternative promoters. In recent years, evidence has been obtained for the expression of steroidogenic enzymes in the nervous system and in cardiac tissue, indicating that these tissues may be involved in the biosynthesis of steroid hormones acting in an autocrine or paracrine manner. This review presents a detailed description of the enzymes involved in the biosynthe...

1,533 citations

Journal ArticleDOI
TL;DR: In the combined SDR superfamily, only one residue is strictly conserved and ascribed a crucial enzymatic function (Tyr 151 in the numbering system of human NAD(+)-linked prostaglandin dehydrogenase), and such a function is supported by chemical modifications, site-directed mutagenesis, and an active site position in those tertiary structures that have been characterized.
Abstract: Short-chain dehydrogenases/reductases (SDR) constitute a large protein family. Presently, at least 57 characterized, highly different enzymes belong to this family and typically exhibit residue identities only at the 15-30% level, indicating early duplicatory origins and extensive divergence. In addition, another family of 22 enzymes with extended protein chains exhibits part-chain SDR relationships and represents enzymes of no less than three EC classes. Furthermore, subforms and species variants are known of both families. In the combined SDR superfamily, only one residue is strictly conserved and ascribed a crucial enzymatic function (Tyr 151 in the numbering system of human NAD(+)-linked prostaglandin dehydrogenase). Such a function for this Tyr residue in SDR enzymes in general is supported also by chemical modifications, site-directed mutagenesis, and an active site position in those tertiary structures that have been characterized. A lysine residue four residues downstream is also largely conserved. A model for catalysis is available on the basis of these two residues. Binding of the coenzyme, NAD(H) or NADP(H), is in the N-terminal part of the molecules, where a common GlyXXXGlyXGly pattern occurs. Two SDR enzymes established by X-ray crystallography show a one-domain subunit with seven to eight beta-strands. Conformational patterns are highly similar, except for variations in the C-terminal parts. Additional structures occur in the family with extended chains. Some of the SDR molecules are known under more than one name, and one of the enzymes has been shown to be susceptible to native, chemical modification, producing reduced Schiff base adducts with pyruvate and other metabolic keto derivatives. Most SDR enzymes are dimers and tetramers. In those analyzed, the area of major subunit contacts involves two long alpha-helices (alpha E, alpha F) in similar and apparently strong subunit interactions. Future possibilities include verification of the proposed reaction mechanism and tracing of additional relationships, perhaps also with other protein families. Short-chain dehydrogenases illustrate the value of comparisons and diversified research in generating unexpected discoveries.

1,187 citations

Journal ArticleDOI
TL;DR: Some of the many actions of estradiol may not be caused by est radiol per se, but may result from the formation of active estrogen metabolite(s) which function as local mediators or may activate their own unique receptors or effectors.
Abstract: Cytochrome P450 enzymes that metabolize estrogens are expressed in the mammary gland, uterus, brain and other target tissues for estrogen action, and this results in the formation of hydroxylated estrogens in these tissues. Estradiol metabolites formed in target tissues at or near estrogen receptors may either be inactive or have important biological effects, and changes in the activities of estrogen-metabolizing enzymes in target tissues may profoundly influence estrogen action. Although some active estrogen metabolites exert hormonal effects in target tissues by interaction with the classical estrogen receptor, other metabolites appear to elicit unique biological responses that are not associated with activation of this receptor. Therefore, some of the many actions of estradiol may not be caused by estradiol per se, but may result from the formation of active estrogen metabolite(s) which function as local mediators or may activate their own unique receptors or effectors. This is an important area in need of more research. The present paper represents a review of the literature and perspectives by the authors on the functional role of estrogen metabolism in target tissues.

960 citations

Journal ArticleDOI
TL;DR: The 11β-hydroxysteroid dehydrogenase (11βHSD) as mentioned in this paper was found to protect the nonselective mineralocorticoid receptor from occupation by glucocorticity, and to modulate access of glucoc Corticoid to glucoc corticoid receptors resulting in protection of the fetus and gonads.

678 citations

References
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Book
15 Jan 2001
TL;DR: Molecular Cloning has served as the foundation of technical expertise in labs worldwide for 30 years as mentioned in this paper and has been so popular, or so influential, that no other manual has been more widely used and influential.
Abstract: Molecular Cloning has served as the foundation of technical expertise in labs worldwide for 30 years. No other manual has been so popular, or so influential. Molecular Cloning, Fourth Edition, by the celebrated founding author Joe Sambrook and new co-author, the distinguished HHMI investigator Michael Green, preserves the highly praised detail and clarity of previous editions and includes specific chapters and protocols commissioned for the book from expert practitioners at Yale, U Mass, Rockefeller University, Texas Tech, Cold Spring Harbor Laboratory, Washington University, and other leading institutions. The theoretical and historical underpinnings of techniques are prominent features of the presentation throughout, information that does much to help trouble-shoot experimental problems. For the fourth edition of this classic work, the content has been entirely recast to include nucleic-acid based methods selected as the most widely used and valuable in molecular and cellular biology laboratories. Core chapters from the third edition have been revised to feature current strategies and approaches to the preparation and cloning of nucleic acids, gene transfer, and expression analysis. They are augmented by 12 new chapters which show how DNA, RNA, and proteins should be prepared, evaluated, and manipulated, and how data generation and analysis can be handled. The new content includes methods for studying interactions between cellular components, such as microarrays, next-generation sequencing technologies, RNA interference, and epigenetic analysis using DNA methylation techniques and chromatin immunoprecipitation. To make sense of the wealth of data produced by these techniques, a bioinformatics chapter describes the use of analytical tools for comparing sequences of genes and proteins and identifying common expression patterns among sets of genes. Building on thirty years of trust, reliability, and authority, the fourth edition of Mol

215,169 citations

Journal ArticleDOI
31 Jan 1986-Cell
TL;DR: By analyzing the effects of single base substitutions around the ATG initiator codon in a cloned preproinsulin gene, ACCATGG is identified as the optimal sequence for initiation by eukaryotic ribosomes.

4,559 citations

Journal ArticleDOI
TL;DR: The structure of the sterol 26-hydroxylase cDNA reveals it to be a mitochondrial cytochrome P-450, and blotting experiments revealed that the mRNA for this enzyme is expressed in many tissues and that it is encoded by a low copy number gene in the rabbit genome.

1,147 citations

Journal ArticleDOI
TL;DR: A dictionary of sites and patterns found in protein sequences, developed, in the last two years, by the author, which is called PROSITE.
Abstract: PROSITE is a compilation of sites and patterns found in protein sequences. The use of protein sequence patterns (or motifs) to determine the function of proteins is becoming very rapidly one of the essential tools of sequence analysis. This reality has been recognized by many authors. While there have been a number of recent reports that review published patterns, no attempt had been made until very recently [5,6] to systematically collect biologically significant patterns or to discover new ones. It is for these reasons that we have developed, since 1988, a dictionary of sites and patterns which we call PROSITE. Some of the patterns compiled in PROSITE have been published in the literature, but the majority have been developed,in the last two years, by the author.

991 citations

01 Jan 1989
TL;DR: In this article, the authors used protein sequencing and molecular cloning techniques to isolate and characterize a cDNA encoding the rabbit mitochondrial sterol 26-hydroxylase, which catalyzes the first step in the oxidation of the side chain of sterol intermediates in the biosynthesis of bile acids.
Abstract: The conversion of cholesterol into bile acids in the liver represents the major catabolic pathway for the removal of cholesterol from the body. In this complex biosynthetic pathway, at least 10 enzymes modify both the ring structure and side chain of cholesterol, resulting in the formation of the primary bile acids, cholic acid, and chenodeoxycholic acid. To gain insight into the details and regulation of this pathway, we have used protein sequencing and molecular cloning techniques to isolate and characterize a cDNA encoding the rabbit mitochondrial sterol 26-hydroxylase. This enzyme catalyzes the first step in the oxidation of the side chain of sterol intermediates in the biosynthesis of bile acids. The structure of the sterol 26-hydroxylase, as deduced by both DNA sequence analysis of the cDNA and protein sequence analysis, reveals it to be a mitochondrial cytochrome P-450. A signal sequence of 36 residues precedes a coding region of 499 amino acids, predicting a molecular weight of 56,657 for the mature protein. The identity of the 26-hydroxylase cDNA was further confirmed by expression in monkey COS cells employing a versatile eukaryotic expression vector. Blotting experiments revealed that the mRNA for this enzyme is expressed in many tissues and that it is encoded by a low copy number gene in the rabbit genome.

965 citations