Abstract
Testin induction: The role of cyclic 3',5'-adenosine monophosphate/protein kinase A signaling in the regulation of basal and lonidamine-induced testin expression by rat Sertoli cells
Grima,Josephine; Cheng,Chuen-yan
Biology of Reproduction 63(6): 1648-1660
Publication date: 2000
Results of previous in vitro and in vivo studies have illustratedthat the expression of testin by Sertoli cells is tightly associatedwith the disruption of Sertoli-germ cell junctions. In the presentstudy, treatment of rats with cadmium chloride (CdCl), whichdisrupted the inter-Sertoli tight junctions, failed to induceany changes in testicular testin expression. In contrast, lonidamine,an antispermatogenic drug that rearranges the Sertoli cell membranemicrofilament structure causing a disruption of Sertoli-germcell adhesion junctions, induced a drastic increase in testiculartestin expression when administered orally. Lonidamine-inducedSertoli cell testin expression involved both ongoing RNA andde novo protein synthesis. Basal testin expression remainedstable during the 27-h incubation with actinomycin D but requiredde novo protein synthesis in vitro. An inhibitor of proteinkinase A, Rp-cAMPS, caused a 50% inhibition of Sertoli celltestin expression at 10 µM within 24 h. A biphasic responsewas noted in testin expression when forskolin was included inthe Sertoli cell culture, and high concentrations of cAMP analogues(1 mM) rapidly reduced testin expression. However, lonidaminecan abolish the inhibitory effect of cAMP analogues on Sertolicell testin expression. These results illustrate that the inductionof testin expression may involve several signal transductionpathways.
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