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Title: Biosynthesis of catalytically active rat testosterone 5. alpha. -reductase in microinjected Xenopus oocytes: Evidence for tissue-specific differences in translatable mRNA

Abstract

The enzyme 4-ene-3-ketosteroid-5{alpha}-oxidoreductase plays a key role in androgen-dependent target tissues, where it catalyzes the conversion of testosterone to the biologically active dihydrotestosterone. The regulation of 5{alpha}-reductase expression has not been studied at the molecular level as the enzyme is a membrane protein that is labile in cell-free homogenates. The authors developed a sensitive bioassay of the enzyme activity expressed in Xenopus oocytes microinjected with rat liver and prostate mRNA. After microinjection, incubation of intact oocytes in the presence of ({sup 3}H)testosterone revealed the in ovo appearance of active 5{alpha}-reductase. Polyandenylylated RNA was fractionated by sucrose gradient centrifugation, and the enzymatic activity was shown to be encoded by a 1,600- to 2,000-base-pair fraction of hepatic poly(A){sup +} RNA. 5{alpha}-Reductase mRNA was most efficiently translated when up to 80 ng of RNA was injected per oocyte. In the injected oocytes, 5{alpha}-reductase mRNA was found to be a short-lived molecule whereas its in ovo translatable 5{alpha}-reductase protein exhibited stable enzymatic activity for over 40 hr. Moreover, the levels of translatable tissue-specific 5{alpha}-reductase mRNAs as monitored in the Xenopus oocytes correlated with the variable 5{alpha}-reductase activities in female rat liver, male rat liver, and prostate homogenates. Altogether, these results provide supporting evidence inmore » favor of the transcriptional control of 5{alpha}-reductase expression in rat tissues.« less

Authors:
; ;  [1]
  1. Hebrew Univ. of Jerusalem (Israel)
Publication Date:
OSTI Identifier:
5564988
Resource Type:
Journal Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America; (USA)
Additional Journal Information:
Journal Volume: 85:16; Journal ID: ISSN 0027-8424
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; OOCYTES; ENZYME ACTIVITY; OXIDOREDUCTASES; BIOSYNTHESIS; AMPHIBIANS; BIOCHEMICAL REACTION KINETICS; CENTRIFUGATION; LIVER; MESSENGER-RNA; PROSTATE; TESTOSTERONE; TRANSCRIPTION; TRITIUM COMPOUNDS; ANDROGENS; ANDROSTANES; ANIMALS; AQUATIC ORGANISMS; BODY; DIGESTIVE SYSTEM; ENZYMES; GERM CELLS; GLANDS; HORMONES; HYDROGEN COMPOUNDS; HYDROXY COMPOUNDS; KETONES; KINETICS; MALE GENITALS; NUCLEIC ACIDS; ORGANIC COMPOUNDS; ORGANS; REACTION KINETICS; RNA; SEPARATION PROCESSES; STEROID HORMONES; STEROIDS; SYNTHESIS; VERTEBRATES; 550201* - Biochemistry- Tracer Techniques

Citation Formats

Farkash, Y, Soreq, H, and Orly, J. Biosynthesis of catalytically active rat testosterone 5. alpha. -reductase in microinjected Xenopus oocytes: Evidence for tissue-specific differences in translatable mRNA. United States: N. p., 1988. Web. doi:10.1073/pnas.85.16.5824.
Farkash, Y, Soreq, H, & Orly, J. Biosynthesis of catalytically active rat testosterone 5. alpha. -reductase in microinjected Xenopus oocytes: Evidence for tissue-specific differences in translatable mRNA. United States. https://doi.org/10.1073/pnas.85.16.5824
Farkash, Y, Soreq, H, and Orly, J. 1988. "Biosynthesis of catalytically active rat testosterone 5. alpha. -reductase in microinjected Xenopus oocytes: Evidence for tissue-specific differences in translatable mRNA". United States. https://doi.org/10.1073/pnas.85.16.5824.
@article{osti_5564988,
title = {Biosynthesis of catalytically active rat testosterone 5. alpha. -reductase in microinjected Xenopus oocytes: Evidence for tissue-specific differences in translatable mRNA},
author = {Farkash, Y and Soreq, H and Orly, J},
abstractNote = {The enzyme 4-ene-3-ketosteroid-5{alpha}-oxidoreductase plays a key role in androgen-dependent target tissues, where it catalyzes the conversion of testosterone to the biologically active dihydrotestosterone. The regulation of 5{alpha}-reductase expression has not been studied at the molecular level as the enzyme is a membrane protein that is labile in cell-free homogenates. The authors developed a sensitive bioassay of the enzyme activity expressed in Xenopus oocytes microinjected with rat liver and prostate mRNA. After microinjection, incubation of intact oocytes in the presence of ({sup 3}H)testosterone revealed the in ovo appearance of active 5{alpha}-reductase. Polyandenylylated RNA was fractionated by sucrose gradient centrifugation, and the enzymatic activity was shown to be encoded by a 1,600- to 2,000-base-pair fraction of hepatic poly(A){sup +} RNA. 5{alpha}-Reductase mRNA was most efficiently translated when up to 80 ng of RNA was injected per oocyte. In the injected oocytes, 5{alpha}-reductase mRNA was found to be a short-lived molecule whereas its in ovo translatable 5{alpha}-reductase protein exhibited stable enzymatic activity for over 40 hr. Moreover, the levels of translatable tissue-specific 5{alpha}-reductase mRNAs as monitored in the Xenopus oocytes correlated with the variable 5{alpha}-reductase activities in female rat liver, male rat liver, and prostate homogenates. Altogether, these results provide supporting evidence in favor of the transcriptional control of 5{alpha}-reductase expression in rat tissues.},
doi = {10.1073/pnas.85.16.5824},
url = {https://www.osti.gov/biblio/5564988}, journal = {Proceedings of the National Academy of Sciences of the United States of America; (USA)},
issn = {0027-8424},
number = ,
volume = 85:16,
place = {United States},
year = {Mon Aug 01 00:00:00 EDT 1988},
month = {Mon Aug 01 00:00:00 EDT 1988}
}