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Parathyroid hormone--quo vadis?
1Department of Medicine, Kobe University School of Medicine.
Nihon Naibunpi Gakkai Zasshi
|December 20, 1988
Summary
Parathyroid hormone (PTH) degradation is crucial in aging due to rising PTH secretion. New enzymes and receptor-mediated mechanisms in kidney cells highlight PTH degradation
Area of Science:
- Endocrinology
- Molecular Biology
- Gerontology
Background:
- Parathyroid hormone (PTH) is vital for calcium regulation, particularly during aging.
- Aging is associated with progressive calcium deficiency and compensatory increases in PTH secretion.
- Heterogeneity of PTH in circulation underscores the need to understand its degradation pathways.
Purpose of the Study:
- To investigate the mechanisms of parathyroid hormone (PTH) degradation.
- To identify enzymes involved in PTH degradation in aging and kidney cells.
- To explore the relationship between PTH action and degradation.
Main Methods:
- Analysis of PTH degradation in liver, kidney, and parathyroid tissues.
- Identification of a novel neutral PTHase in rat kidney cytosolic fractions.
- Investigation of PTH degradation in UMR-106 and OK cell lines using receptor-mediated mechanisms.
Main Results:
- Cathepsins B and D were confirmed as PTH-degrading enzymes in the liver and kidney.
- A new neutral PTHase was identified in rat kidney cytosolic fractions.
- PTH degradation in bone and kidney cells involves a plasma membrane chymotrypsin-like enzyme, modulated by cyclic AMP-A-kinase and C-kinase systems.
Conclusions:
- PTH degradation involves multiple enzymatic pathways, including novel ones in kidney cells.
- PTH degradation is linked to PTH action, suggesting a new physiological role.
- Understanding PTH degradation is important for addressing calcium dysregulation in aging.