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Abstract

GATA-1 and GATA-4 transactivate inhibin/activin β-B-subunit gene transcription in testicular cells (PDF) (HTML) 
Feng,Zong-Ming; Wu,Ai Zhen; Zhang,Zhifang; Chen,Ching-Ling C.
Molecular Endocrinology 14(11): 1820-1835
Publication date: 2000

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We have recently demonstrated that a testicular GATA-bindingprotein, GATA-1, up-regulates the transcription of inhibin -subunitgene through interaction with GATA motifs in the promoter regionin MA-10, a mouse Leydig tumor cell line. In this study, we showedthat both GATA-1 and GATA-4 also transactivated the transcriptionfrom the promoter for the 4.8-kb inhibin/activin ß-B-subunitgene transcripts, ß-B(4.8)-subunit promoter, in two testicularcell lines, MA-10 and MSC-1, which is a mouse Sertoli cell line.The abilities of GATA-1 and GATA-4 interacting with GATA and/or GATA-likesequences to transactivate the ß-B(4.8)-subunit promoter werenext examined by mutation analysis. Mutations of GATA or GATA-like sequencescaused no apparent effect or only a small decrease in the basaltranscriptional activity of this promoter. However, mutationof the GATA motif at -65 markedly decreased 60-70% ofthe effect of GATA-1 on the transactivation of ß-B(4.8)-subunitpromoter in both MA-10 and MSC-1 cells. In addition, mutationof the GATA motif in MSC-1 cells also reduced 40-50% ofthe effect of GATA-4 to transactivate this promoter. Interestingly,mutation of GATT at -42 caused a 70-90% increase in thetransactivation of ß-B(4.8)-subunit promoter by GATA-1or GATA-4. No significant change in the promoter activity was observedwhen GATT at -177 or GATC at -201 was mutated. Electrophoreticmobility shift assay confirmed the above observations that theseGATA-binding proteins interacted with the GATA motif at -65 andGATT at -42, but not with GATC at -201 or GATT at -177. Serial deletionfrom the 5'-end of the basal promoter, from -226 to -90, markedlydecreased the basal transcription, but increased the effectof GATA-1 on transactivation of the ß-B(4.8)-subunit promoter.In summary, our observations suggest that the two GATA-bindingproteins transactivate the ß-B(4.8)-subunit promoter intesticular cells via complicated mechanisms. Both GATA-1 andGATA-4 factors act through the GATA motif at -65 and GATT at-42 to positively and negatively regulate the transcriptionfrom this promoter, respectively. Furthermore, GATA-1 may alsointeract directly or indirectly with DNA sequences at -180 to-90 to regulate the ß-B(4.8)-subunit promoter.

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