Stage-specific nuclear expression of NF-kappaB in mammalian testis.
The Rel/nuclear factor (NF)-kappaB family of transcription factors are important intracellular conveyors of extracellular signals in a number of systems. However, little is known of their roles in the specialized, hormonally regulated environment of the mammalian testis. In this study NF-kappaB p50 and p65 proteins were found to be constitutively present and active in the nucleus of Sertoli cells cultured from rat testis. In vivo, NF-kappaB proteins are present in the nucleus of Sertoli cells during all 14 (I-XIV) cyclical stages of spermatogenesis; however, nuclear NF-kappaB expression was elevated in stage XIV and remained high in stages I-VII. In contrast, NF-kappaB p50 and p65 subunits are transiently expressed in the nuclei of germ cells with peak levels found in pachytene spermatocytes during stages VII-XI and lower levels in stage I-VII spermatids. Tumor necrosis factor-alpha, which is produced by round spermatids in the testis, increased nuclear NF-kappaB binding activity when added to Sertoli cells. Stimulation of Sertoli cells with activators of the cAMP-protein kinase A (PKA) signaling pathway such as forskolin or FSH also increased NF-kappaB DNA binding activity. Consistent with the cellular localization studies, NF-kappaB was found to be activated as high basal levels of NF-kappaB-stimulated reporter gene expression were detected in transient transfection studies of Sertoli cells. Addition of tumor necrosis factor-alpha to Sertoli cells further stimulated kappaB enhancer-mediated transcription. These findings suggest that NF-kappaB proteins are stage specifically localized to Sertoli cell and spermatocyte nuclei and may play a role in the regulation of stage-specific gene expression during the process of spermatogenesis.
Delfino
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Department of Cell Biology and Physiology, University of Pittsburgh, Pennsylvania 15261, USA.
Walker
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WH
D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D004790:Enzyme Induction / Q000187:drug effects; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D008297:Male; D008970:Molecular Weight; D016328:NF-kappa B / Q000378:metabolism*; D020033:Protein Isoforms / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism*; D013737:Testis / Q000166:cytology / Q000254:growth & development*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016328:NF-kappa B; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha; D005576:Colforsin; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D013755:Tetradecanoylphorbol Acetate