Transcription of platelet-derived growth factor receptor   in Leydig cells involves specificity protein 1 and 3

Abstract

Platelet-derived growth factor (PDGF) A is secreted by Sertoli cells and acts on Leydig precursor cells, which express the receptor PDGFRA, triggering their differentiation into steroidogenically active Leydig cells. There is, however, no information regarding the molecular mechanisms that govern Pdgfra expression in Leydig cells. In this study, we isolated and characterized a 2 . 2 kb fragment of the rat Pdgfra 5 0 -flanking sequence in the TM3 Leydig cell line, which endogenously expresses Pdgfra. A series of 5 0 progressive deletions of the Pdgfra promoter was generated and transfected in TM3 cells. Using this approach, two regions (K183/K154 and K154/K105), each conferring 46% of Pdgfra promoter activity, were identified. To better define the regulatory elements, trinucleotide mutations spanning the K154/K105 region were introduced by site-directed mutagenesis in the context of the K2 . 2 kb Pdgfra promoter.Mutations that altered the TCCGAGGGAAAC sequence at K138 bp significantly decreased Pdgfra promoter activity in TM3 cells. Several proteins from TM3 nuclear extracts were found to bind to this G(C/A) motif in electromobility shift assay. Two of the proteins were identified as the transcription factors SP1 and SP3. Using transient transfections of TM3 Leydig cells, SP1 and SP3 were found to activate the Pdgfra promoter by threefold. The SP1/SP3-dependent activation of the Pdgfra promoter was severely blunted when the G(C/A) motif was mutated. Our study provides new insights into the regulatory mechanisms of Pdgfra transcription in Leydig cells, which includes a role for the transcription factors SP1 and SP3.

Friend of GATA suppresses the GATA-induced transcription of hepcidin in hepatocytes through a GATA-regulatory element in the HAMP promoter

“…The increase in activity may have been due to elimination of repressive elements upstream of K1117 bp. The presence of alternating d(TG)n-type purine-pyrimidine di-nucleotide repeats in the deleted region could have suppressed the HAMP promoter activity (Naylor & Clark 1990, Bergeron et al 2011; however, in silico analysis of the deleted region revealed a potential CP-2 transcription factor binding site K1191/K1181 with a WT sequence -GGCCATGCCCT- (Heinemeyer et al 1998). CP-2 is expressed in hepatocytes and acts either as a transcription enhancer or repressor (Veljkovic & Hansen 2004, Jang et al 2010.…”

Insights into the Development of the Adult Leydig Cell Lineage from Stem Leydig Cells

“…The expression of PDGFRA is regulated by the transcription factors SP1 and SP3 (Bergeron et al, 2011). The downstream signaling of PDGFRA in regulating the commitment of SLCs into the LC lineage is still unclear.…”

Okadaic acid inhibits the trichostatin A-mediated increase of human CYP46A1 neuronal expression in a ERK1/2-Sp3-dependent pathway

“…The SP family of transcription factors, including Sp3, is highly regulated at the posttranslational level. Although Sp3 is able to up- ( 35,36 ) and down-regulate gene transcription (37)(38)(39), phosphorylation is generally associated with increased DNA binding activity and, consequently, increased transcriptional activation ( 35,40 ). Modifi cations such as acetylation have also been described to activate ( 21 ) and repress ( 41 ) Sp3 transcriptional activity, whereas sumoylated Sp3 signifi cantly represses transcription (42)(43)(44).…”