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Leptin-mediated decrease of cyclin A2 and increase of cyclin D1 expression: relevance for the control of prepubertal
Joanna Fombonne1, Céline Charrier, Isabelle Goddard
1Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale Unité 29, Parc Scientifique de Luminy-BP13, F-13273 Marseille, Cedex 09, France.
Endocrinology
|February 17, 2007
Summary
Leptin, a hormone crucial for male fertility, inhibits the division of immature Leydig cells. It also appears to promote Leydig cell differentiation, potentially involving cyclin D1.
Area of Science:
- Reproductive Endocrinology
- Cell Biology
- Hormone Signaling
Background:
- Leydig cell number is critical for testosterone production and depends on prepubertal Leydig cell proliferation.
- Leptin regulates proliferation in various cell types and plays a role in male fertility.
Purpose of the Study:
- To investigate if leptin controls the proliferative capacity of prepubertal Leydig cells.
- To elucidate the mechanisms by which leptin affects Leydig cell division and differentiation.
Main Methods:
- Quantitative real-time RT-PCR and Western blot analysis of G1/S-phase cyclins.
- Bromodeoxyuridine incorporation and Ki67 immunocytochemistry for DNA synthesis and cell cycling.
- Immunohistochemistry for cyclin D1 and relaxin-like factor; small interference RNA for cyclin D1 knockdown.
Main Results:
- Prepubertal Leydig cells express the leptin receptor (Ob/Rb), indicating direct responsiveness to leptin.
- Leptin decreases cyclin A2 and increases cyclin D1 expression, preceding a reduction in Leydig cell number.
- Leptin inhibits cell division and increases mRNA levels of Leydig cell differentiation markers (relaxin-like factor, 3beta-hydroxysteroid dehydrogenase).
- Cyclin D1 expression increases with Leydig cell differentiation, and its knockdown affects leptin-induced differentiation.
Conclusions:
- Leptin inhibits prepubertal Leydig cell division through a mechanism independent of cyclin D.
- Cyclin D1 may play a role in leptin-induced Leydig cell differentiation.
- Leptin directly influences Leydig cell proliferation and differentiation, impacting male reproductive function.
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