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Characterization of 17 beta-hydroxysteroid dehydrogenase IV
J F Carstensen1, J G Tesdorpf, M Kaufmann
1Max-Planck-Institut für Experimentelle Endokrinologie, Hannover, Germany.
The Journal of Endocrinology
|September 1, 1996
Summary
17 beta-Hydroxysteroid dehydrogenase (17 beta-HSD) IV, an enzyme for steroid inactivation, is highly expressed in porcine liver and kidney. Its expression is differentially regulated by protein kinase C, impacting steroid synthesis.
Area of Science:
- Biochemistry
- Molecular Biology
- Endocrinology
Background:
- 17 beta-Hydroxysteroid dehydrogenase (17 beta-HSD) IV is an enzyme involved in steroid metabolism.
- It differs significantly in amino acid sequence from other 17 beta-HSD enzymes (I-III).
Purpose of the Study:
- To characterize the 17 beta-HSD IV enzyme and its expression patterns.
- To investigate the regulation of 17 beta-HSD IV by the protein kinase C pathway.
Main Methods:
- Analysis of mRNA and protein expression.
- Enzyme activity assays.
- Immunofluorescence.
- Cell culture and stimulation (phorbol-myristate-acetate, vitamin D).
Main Results:
- 17 beta-HSD IV is translated from a 2.9 kb mRNA into an 80 kDa protein, cleaved to a 32 kDa active enzyme.
- The enzyme forms 75 kDa dimers and is not glycosylated despite potential sites.
- Highest expression and activity observed in liver and kidney, with lower levels in gonads.
- Immunofluorescence localized 17 beta-HSD IV to granulosa, Leydig, and Sertoli cells.
- Protein kinase C activation differentially regulates steroid synthesis and inactivation, decreasing 17 beta-HSD IV mRNA with increased aromatase.
Conclusions:
- 17 beta-HSD IV plays a role in steroid inactivation, with distinct expression and regulation.
- The protein kinase C pathway modulates steroidogenic gene expression, affecting both synthesis and inactivation pathways.