Estrogen-induced proliferation of normal endometrial glandular cells is initiated by transcriptional activation of cyclin D1 via binding of c-Jun to an AP-1 sequence

Abstract

To explore the mechanism of estrogen-induced growth of normal endometrium, the transactivation system of the cyclin D1 gene was analysed using cultured normal endometrial glandular cells. Estradiol (E2) treatment of cultured normal endometrial glandular cells induced upregulation of c-Jun, and then cyclin D1 proteins, followed by serial expressions of cyclins E, A and B1 proteins. Increase in the mRNA expression of cyclin D1 preceded the protein expression of cyclin D1 under E2 treatment. A luciferase assay using deletion constructs of the cyclin D1 promoter indicated that E2-induced increase in transcriptional activity was observed in reporters containing AP-1-binding site sequence, and that in the absence of E2, cotransfection of c-Jun also showed increase of transcriptional activity in the same reporters with AP-1 sequence. A gel shift assay using nuclear extract from E2-treated endometrial glandular cells and AP-1 sequences of the cyclin D1 promoter indicated specific binding between c-Jun protein and the promoter. Transfection of c-jun antisense oligonucleotides to the glandular cells resulted in the suppression of the E2-induced upregulation of cyclin D1 mRNA and protein. These findings suggest that E2-induced proliferation of normal endometrial glandular cells is initiated by transcriptional activation of cyclin D1 via binding of cJun to the AP-1 sequences.

Involvement of protein phosphatase 2A nuclear accumulation and subsequent inactivation of activator protein-1 in leptomycin B-inhibited cyclin D1 expression

“…(2) PP2A represses AP-1 activity by dephosphorylation of c-Jun on Ser-63 (Alberts et al, 1993;AlMurrani et al, 1999;Ramirez et al, 2005). (3) c-Jun enhances cell proliferation through induction of cyclin D1 transcription, shown by several reports (Watanabe et al, 1996;Shiozawa et al, 2004;Whang et al, 2005). The possibility that the involvement of c-Jun in the mechanism of LMB-induced reduction of cyclin D1 expression was further supported by our findings: (1) serum-induced cyclin D1 expression is required for AP-1 site in the promoter region of cyclin D1 gene, and the residual promoter activity of AP-1 site-deleted or pointmutated cyclin D1 promoter construct is no longer inhibited by LMB treatment.…”

Transcriptional regulation of endothelial nitric oxide synthase expression in uterine artery endothelial cells by c-Jun/AP-1

“…However, whether other members of the AP-1 transcription factors play a role in the regulation of NOS3 expression in UAEC also needs to be investigated. Furthermore, the AP-1 family oncogene products can be rapidly induced by a variety of physiological and pathophysiological stimuli important for cell function, including hormones such as estrogen (Shiozawa et al, 2004), growth factors (Inoue et al, 1995;Zheng et al, 1999), shear stress (Li et al, 2003), protein kinase C activators (Navarro-Antolin et al, 2000), tumor necrosis factor-α (Hanazawa et al, 1994), lipopolysaccharide (Schwartz et al, 1997;Wong et al, 2004), and angiotensin II (Clark et al, 1992). In the uterine and placental circulations, the role of AP-1 in estrogen (Chen et al, 2006;Weiner et al, 1994) and angiogenic growth factors such as basic fibroblast growth factor (Zheng et al, 1999) as well as angiotensin II (Zheng et al, 2005) stimulation of endothelial NOS3 expression is currently unknown, which will be important to be investigated because of the key role(s) that these factors play in the regulation of uterine and placental vascular activity and reactivity during pregnancy.…”

Upregulation of rat Ccnd1 gene by exendin-4 in pancreatic beta cell line INS-1: interaction of early growth response-1 with cis-regulatory element

“…Preparation of nuclear extracts and electrophoretic mobility shift assay Preparation of nuclear proteins from INS-1 cells and electrophoretic mobility shift assays (EMSAs) was performed as described previously [15]. In supershift studies, 2 μg of each antibody was preincubated with the nuclear extract for 10 min at 4°C before addition of the labelled probe.…”

“…Ccnd1 expression appears to be predominantly regulated at the transcriptional level, although post-transcriptional mechanisms are also involved [13,14]. The promoter region of Ccnd1 contains multiple potential cis-regulatory elements, including binding sites for AP1, signal transducer and activator transcription 5 (STAT5), EGR1, specific protein 1 (SP1) and activating transcription factor (ATF)/cyclic AMP-responsive element binding protein (CREB), which are important for the transcriptional activation of Ccnd1 [15][16][17]. The AP1 binding site has been shown to be involved in angiotensin II-induced activation of the Ccnd1 promoter in human adrenal cells [15].…”

“…The promoter region of Ccnd1 contains multiple potential cis-regulatory elements, including binding sites for AP1, signal transducer and activator transcription 5 (STAT5), EGR1, specific protein 1 (SP1) and activating transcription factor (ATF)/cyclic AMP-responsive element binding protein (CREB), which are important for the transcriptional activation of Ccnd1 [15][16][17]. The AP1 binding site has been shown to be involved in angiotensin II-induced activation of the Ccnd1 promoter in human adrenal cells [15]. The STAT5 binding site has been implicated in cytokine-dependent proliferation of haematopoietic cells [16].…”