The closely related POU family transcription factors Brn-3a and Brn-3b are expressed in distinct cell types in the testis

• Published in: The international journal of biochemistry & cell biology 2001-10, Vol.33 (10), p.1027-1039
• Main Authors: Budhram-Mahadeo, Vishwanie, Moore, Alison, Morris, Peter J., Ward, Teresa, Weber, Barbara, Sassone-Corsi, Paolo, Latchman, David S.
• Format: Article
• Language: English
• Subjects: Animals; Blotting, Western; Brn-3a; Brn-3b; Cells, Cultured; Cyclic AMP Response Element Modulator; DNA-Binding Proteins; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; DNA-Binding Proteins - physiology; Female; Gene Expression Regulation; Gene Expression Regulation - physiology; Genes, BRCA1; Genes, BRCA1 - genetics; Genes, BRCA1 - physiology; Humans; Immunohistochemistry; Life Sciences; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; POU Domain Factors; POU family transcription; Rats; Rats, Sprague-Dawley; Repressor Proteins; Repressor Proteins - physiology; Reverse Transcriptase Polymerase Chain Reaction; Spermatids; Spermatids - immunology; Spermatids - metabolism; Spermatogonia; Spermatogonia - growth & development; Spermatogonia - immunology; Spermatogonia - metabolism; Testis; Testis - cytology; Testis - metabolism; Tissue Distribution; Transcription Factor Brn-3; Transcription Factor Brn-3A; Transcription Factor Brn-3B; Transcription Factors; Transcription Factors - genetics; Transcription Factors - metabolism; Transfection
• ISSN: 1357-2725; 1878-5875; 1357-2725
• DOI: 10.1016/S1357-2725(01)00069-3

Although the Brn-3a and Brn-3b POU family transcription factors were originally identified in neuronal cells, their expression in some non neuronal cell types has previously been reported. Here we report that Brn-3a and Brn-3b are also expressed in the testis with expression of each factor being observed at distinct stages of germ cell development. Thus, Brn-3a is expressed in spermatogonia whereas Brn-3b expression is observed in post-meiotic spermatids. In agreement with this, Brn-3a expression is detectable much earlier than that of Brn-3b in testes derived from sexually immature postnatal animals. Similarly, Brn-3b expression is absent in knock out mice lacking a functional CREM transcription factor in which the later stages of germ cell development do not occur, whereas Brn-3a expression is observed at similar levels in the testes of these knock out mice. Interestingly, the cellular pattern of Brn-3a expression during germ cell development coincides with that of the BRCA-1 anti-oncogene. Consistent with the possibility that Brn-3a may regulate expression of BRCA-1 in the testis, we have shown that Brn-3a can strongly activate the BRCA-1 promoter in co-transfection experiments whereas Brn-3b does not have this effect. Hence, as observed in neuronal cells, Brn-3a and Brn-3b may play distinct and important functional roles in the regulation of gene expression during germ cell development.