Positive and negative regulatory elements control the steroid-responsive ovalbumin promoter

Abstract

Steroid hormones regulate the transcriptional activity of the chicken ovalbumin gene both in vivo and in cell culture. To identify the regulatory elements involved, primary oviduct cell cultures were transfected with constructs containing the promoter and 5'-flanking region of the ovalbumin gene fused to the bacterial chloramphenicol acetyltransferase (CAT) gene. Induction of the OvCAT genes by estrogen, progesterone, or corticosterone mimics that of the endogenous ovalbumin gene, indicating that the transfected DNA is accurately regulated. Deletion analysis revealed that a steroid response element (SRE) resides between nucleotide coordinates -880 and -585 and that a negative regulatory element (NRE) resides between -350 and -248 in the ovalbumin gene. Thus, an NRE represses expression of the ovalbumin gene unless steroid hormones relieve this negative control through interactions involving a more distal SRE. Neither the SRE nor the NRE alone regulates the heterologous thymidine kinase promoter, suggesting either that they function as a single entity or that they are conditional regulatory elements. The NRE is functional in MCF-7 cells, but the SRE cannot be activated by steroids in this heterologous estrogen-responsive cell line. These data indicate that the steroid-receptor complex induces the ovalbumin gene through direct or indirect actions at an SRE to relieve represssion at an NRE.

Estrogen Opposes the Apoptotic Effects of Bone Morphogenetic Protein 7 on Tissue Remodeling

“…The estrogen-inducible transcription factor delta-EF1 (7) is shown to illustrate that a concomitant inductive response occurs in estrogen-stimulated oviducts, confirming that estrogen does not have a generalized negative effect on transcription in the oviduct. To the contrary, the genes for ovalbumin (62), connexin 43 (20), glycoprotein (27), cystic fibrosis transmembrane regulator (56), leukemia inhibitory factor (54), H-ras (9), and myosin light-chain kinase (57) are induced by estrogen in the oviducts of various species. Additionally, the genes for epidermal growth factor and TGF-␣ are induced in the oviduct (63), demonstrating that some members of the TGF-␤ superfamily can respond positively to estrogen in this tissue and that there is some specificity in the repression of the cBMP-7 gene by estrogen.…”

Nerve growth factor-induced derepression of peripherin gene expression is associated with alterations in proteins binding to a negative regulatory element.

“…This two-step model of activation explains the inability of the wild-type -305-CAT construct to be fully activated by NGF (Fig. 7B) (60). The upstream steroiddependent regulatory element induces the ovalbumin gene in the presence of hormone by derepressing the NRE (19,63).…”

Regulation of the Chicken Ovalbumin Gene by Estrogen and Corticosterone Requires a Novel DNA Element That Binds a Labile Protein, Chirp-I

“…All steroidal induction of the Ov gene maps to a 120-bp region from Ϫ900 to Ϫ780, relative to the transcriptional start site, called the steroid-dependent regulatory element (SDRE) (36,38). The SDRE does not function as an enhancer and requires the presence of another region from Ϫ308 to ϩ9 to confer regulation by steroid hormones on a heterologous or homologous promoter (36).…”