Purification and Cloning of Type A/B hnRNP Proteins Involved in Transcriptional Activation from the Rat spi 2 Gene GAGA Box

Abstract

The GAGA box of the rat serine protease inhibitor 2 (spi 2) genes not only acts as a basal promoter element, but also mediates transcriptional activation by growth hormone and interleukin-6. The GAGA box is separated from the TATA box by only 12 bp, and this close association is required for efficient transcription. Hence, the GAGA box may influence transcription efficiency through interactions between GAGA box binding proteins and some components of the RNA polymerase II complex. Here we report the cloning of two GAGA box-binding proteins termed p38 and p40, that belong to the type A/B heterogeneous nuclear ribonucleoprotein subgroup. GAGA box mutations that diminish the affinity for p38 and p40 decrease basal and GH-induced reporter gene expression. Furthermore, nuclear extracts depleted of p38 and p40 can no longer support GAGA box-dependent in vitro transcription. Therefore, two polypeptides previously assigned to a family of RNA processing proteins also act as DNA-binding, promoter-specific transcription factors.

Heterogeneous nuclear ribonucleoprotein A/B and G inhibits the transcription of gonadotropin-releasing-hormone 1

“…Rat hnRNP-A/B homolog, termed AlF-C1, is involved in repressing rat aldolase B (AldB) gene expression and in DNA replication initiation (Saitoh et al, 2002;Yabuki et al, 2001). In addition to its repressive function, hnRNP-A/Bs have also been shown to be necessary for the transcriptional activation of the rat serine protease inhibitor 2 (spi-2) gene (Leverrier et al, 2000).…”

“…In vitro experiments showed a repressive function of ssDBF (hnRNP-A/B) on estrogen dependent activity of the apoVLDL II promoter (Smidt et al, 1995). hnRNP-A/B is also involved in the growth hormone dependent transcriptional activation of spi-2 genes (Leverrier et al, 2000). Other hnRNPs, e.g.…”

Functional Impact of Heterogeneous Nuclear Ribonucleoprotein A2/B1 in Smooth Muscle Differentiation from Stem Cells and Embryonic Arteriogenesis

“…The significance of these RNA-binding domains has been strongly linked to its importance in gene post-transcription, mature mRNA cytoplasm transportation, and protein translation through its binding to pre-RNAs (15,16). However, accumulating evidence also suggests that RNA recognition motif and arginine/glycine-rich box of hnRNPs are involved in the binding of single-stranded DNA (17), telomere biogenesis (18,19), and transcriptional regulation (20,21). For example, it has been reported that hnRNPA2/B1 can bind to the promoters of c-myc, Apoe, vitamin D receptor, breast cancer 1, and gonadotropin-releasing hormone 1 genes and regulate the gene expressions (22)(23)(24)(25)(26).…”

Cloning and Characterization of Porcine CArG Binding Factor A Expression in the Anterior Pituitary

“…The roles of CBF-A have been demonstrated in the regulation of diverse genes, such as the kappa [8], human smooth muscle α-actin [7], rat serine protease inhibitor 2 (spi2) [24], Ha-ras [10] and cyclo-oxygenase 2 (COX-2) genes containing AU-rich-element (ARE) [25]. In the pituitary, while the participation of CBF-A has not yet been reported, a CArG box is arguably present in the LHβ promoter [13,14].…”