Transcriptional downregulation of the retina-specific QR1 gene by pp60v-src and identification of a novel v-src-responsive unit.

Abstract

The embryonic avian neuroretina (NR) is part of the central nervous system and is composed of various cell types: photoreceptors and neuronal and Muller (glial) inactivation. Cl is also a target for regulation during development. We have identified the DNA binding site for the Cl complex, a repeated GCTGAC sequence, and shown that mutations in this element abolish binding of this factor as well as transcription of the gene at the nonpermissive temperature. Neither formation of Cl nor that of C2 seems to involve factors known to be targeted in the pp60v" cascade. Our data suggest that Cl could be a novel target for both developmental control and oncogene-induced cell growth regulation.

mafA, a novel member of the maf proto-oncogene family, displays developmental regulation and mitogenic capacity in avian neuroretina cells

“…We showed that transcription of QR1 also correlates with cell quiescence in vitro, in NR cells expressing a v-src mutant, conditionally defective for its mitogenic capacity (Guermah et al, 1991). We identi®ed in the QR1 promoter a quiescence-responsive element, termed A box (Pierani et al, 1993, that displayed important similarities with the Maf recognition element (MARE) (Kataoka et al, 1994b). We also showed that transcription factors of the Maf family indeed regulate transcription of the QR1 gene through the A box .…”

v-Src-mediated Down-regulation of SSeCKS Metastasis Suppressor Gene Promoter by the Recruitment of HDAC1 into a USF1-Sp1-Sp3 Complex

“…With the exception of studies on the QR1 gene (50,54), little is known regarding the mechanism by which v-Src down-regulates gene transcription. In this study, we used the ssecks gene as a prototype in order to explore the mechanisms involved in v-Src-mediated gene repression.…”

Characterization of a novel quiescence responsive element downregulated by v-Src in the promoter of the neuroretina specific QR1 gene

“…7345/+55; 71119/+55; 71173/+55; 71265/+55 and 71265A7/+55 reporter constructs have been described (Pierani et al, 1993). C7 mutation was introduced into 71173/+55; 71265/+55 and 71265A7/+55 plasmids by PCR mediated mutagenesis.…”

“…For each construct, one plate was subsequently incubated at 378C and the second at 418C. Forty hours later cell lysates were prepared and CAT and bgalactosidase activity measured as previously described (Pierani et al, 1993). Percentage of chloramphenicol conversion was calculated by scanning the thin layer chromatographic plates with a Phosphorimager instrument (Molecular Dynamics) and Image Quant Software.…”

“…Transcriptional stimulation by the A box was shown to involve binding of an activator complex named C1 (Pierani et al, 1993). We then showed that C1 contains a member of the Maf family (Pouponnot et al, 1995), a group of transcription factors mainly involved in the control of di erentiation, notably in the postmitotic retina Rehemtulla et al, 1996).…”