Transforming growth factor-β inhibits DNA synthesis in immature rat Leydig cells in vitro
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- 作者：Khan ; Shafiq A. ; Mirsafian ; Masoud ; Howdeshell ; Kembra ; Dorrington ; Jennifer H.
- 关键词：Testis ; Leydig cells ; DNA synthesis ; Transforming growth factor-β ; Cyclin-dependent kinases
- 刊名：Molecular and Cellular Endocrinology
- 出版年：1999
- 出版时间：February 25, 1999
- 年：1999
- 卷：148
- 期：1-2
- 页码：21-28
- 全文大小：172 K
文摘
TGFβ isoforms and its receptors are present in the testis and regulate in vitro function of various testicular cells. We have investigated the effects of TGFβ on basal and mitogen stimulated in vitro proliferation of immature rat Leydig cells. Leydig cells were cultured with TGFβ1, either alone or in combination with hCG, steroidogenesis-inducing protein (SIP), interleukin-1β (IL-1β), insulin or TGFα, and the incorporation of [3H]thymidine into DNA was determined. TGFβ1 blocked the stimulatory effects of hCG, SIP, IL-1β, insulin and TGF-α on DNA synthesis. Since G1- to S-phase transition depends upon cyclins and their associated kinases (cdks), we investigated the effects of TGFβ on cdks. Immunoreactive levels of cdc2 (or cdk1) and cdk2 were significantly decreased in Leydig cells treated with TGFβ1. We conclude that TGFβ1 inhibits proliferation of immature rat Leydig cells and this effect may be mediated, at least in part, through down-regulation of cdc2 and cdk2 synthesis.