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Characterization and localization of human type10 17beta-hydroxysteroid dehydrogenase
1Department of Pharmacology, New York State Institute for Basic Research in Developmental Disabilities, New York 10314, USA.
European Journal of Biochemistry
|September 18, 2001
Summary
Human 17beta-hydroxysteroid dehydrogenase type 10 (17β-HSD10) is primarily found in liver and gonads, not skeletal muscle. This enzyme is located in mitochondria, enabling them to regulate sex steroid levels.
Area of Science:
- Biochemistry
- Cell Biology
- Endocrinology
Background:
- 17beta-hydroxysteroid dehydrogenase type 10 (17β-HSD10), also known as ER-associated amyloid beta-binding protein (ERAB), is an enzyme with debated localization and function.
- Previous studies suggested ERAB's presence in the endoplasmic reticulum (ER), influencing amyloid beta binding.
- Understanding 17β-HSD10's precise location is crucial for elucidating its role in steroid metabolism and potential disease pathology.
Purpose of the Study:
- To determine the accurate tissue distribution and subcellular localization of human 17β-HSD10.
- To clarify the metabolic functions of 17β-HSD10, particularly its role in steroid hormone metabolism.
- To resolve discrepancies regarding its previously reported ER localization versus its actual mitochondrial function.
Main Methods:
- Investigated tissue distribution of 17β-HSD10 across human organs, including liver, gonads, and skeletal muscle.
- Employed immunocytochemical studies and subcellular fractionation techniques to determine protein localization.
- Utilized protocols to isolate mitochondrial and ER fractions, assessing ERAB presence in each.
Main Results:
- Human 17β-HSD10 is abundant in the liver and gonads, with negligible amounts in skeletal muscle.
- Contrary to prior assumptions, immunocytochemistry showed 17β-HSD10 is not detectable in the ER of normal tissues.
- Studies confirmed that 17β-HSD10 is predominantly located in mitochondria, not the ER.
- Mitochondrial localization of 17β-HSD10 was confirmed, even when ER-rich fractions were contaminated with mitochondria.
Conclusions:
- Human 17β-HSD10 is a mitochondrial enzyme, distinguishing it from other known 17beta-hydroxysteroid dehydrogenases.
- The mitochondrial localization of 17β-HSD10 allows mitochondria to modulate intracellular levels of active sex steroids.
- This finding necessitates a re-evaluation of previous studies on ERAB and its role in amyloid beta binding and ER-associated processes.