Cobalt Chloride-Induced Estrogen Receptor α Down-Regulation Involves Hypoxia-Inducible Factor-1α in MCF-7 Human Breast Cancer Cells

Abstract The estrogen receptor (ER) is down-regulated under hypoxia via a proteasome-dependent pathway. We studied the mechanism of ERα degradation under hypoxic mimetic conditions. Cobalt chloride-induced ERα down-regulation was dependent on the expression of newly synthesized protein(s), one possibility of which was hypoxia-inducible factor-1α (HIF-1α). To examine the role of HIF-1α expression in ERα down-regulation under hypoxic-mimetic conditions, we used a constitutively active form of HIF-1α, HIF-1α/herpes simplex viral protein 16 (VP16), constructed by replacing the transactivation domain of HIF-1α with that of VP16. Western blot analysis revealed that HIF-1α/VP16 down-regulated ERα in a dose-dependent manner via a proteasome-dependent pathway. The kinase pathway inhibitors PD98059, U0126, wortmannin, and SB203580 did not affect the down-regulation. A mammalian two-hybrid screen and immunoprecipitation assays indicated that ERα interacted with HIF-1α physically. These results suggest that ERα down-regulation under hypoxia involves protein-protein interactions between the ERα and HIF-1α.

Download Full-text

Direct interaction of the tau 1 transactivation domain of the human glucocorticoid receptor with the basal transcriptional machinery

Molecular and Cellular Biology ◽

10.1128/mcb.13.1.399-407.1993 ◽

1993 ◽

Vol 13 (1) ◽

pp. 399-407

Author(s):

I J McEwan ◽

A P Wright ◽

K Dahlman-Wright ◽

J Carlstedt-Duke ◽

J A Gustafsson

Keyword(s):

Glucocorticoid Receptor ◽

Protein Interactions ◽

Core Promoter ◽

Specific Interaction ◽

Direct Interaction ◽

Dependent Manner ◽

Transactivation Domain ◽

Yeast Saccharomyces Cerevisiae ◽

Concentration Dependent Manner

We have used a yeast (Saccharomyces cerevisiae) cell free transcription system to study protein-protein interactions involving the tau 1 transactivation domain of the human glucocorticoid receptor that are important for transcriptional transactivation by the receptor. Purified tau 1 specifically inhibited transcription from a basal promoter derived from the CYC1 gene and from the adenovirus 2 major late core promoter in a concentration-dependent manner. This inhibition or squelching was correlated with the transactivation activity of tau 1. Recombinant yeast TATA-binding protein (yTFIID), although active in vitro, did not specifically reverse the inhibitory effect of tau 1. In addition, no specific interaction between tau 1 and yTFIID could be shown in vitro by affinity chromatography. Taken together, these results indicate that the tau 1 transactivation domain of the human glucocorticoid receptor interacts directly with the general transcriptional apparatus through some target protein(s) that is distinct from the TATA-binding factor. Furthermore, this assay can be used to identify interacting factors, since after phosphocellulose chromatography of a whole-cell yeast extract, a fraction that contained an activity which selectively counteracted the squelching effect of tau 1 was found.

Download Full-text

Correlation between hypoxia inducible factor -1α and renin expression in rats kidney induced by cobalt chloride

Medical Journal of Indonesia ◽

10.13181/mji.v21i3.491 ◽

2012 ◽

pp. 128

Author(s):

Ani R. Prijanti ◽

Raafqi Ranasasmita ◽

Yurika Sandra ◽

Septelia I. Wanandi

Keyword(s):

Cobalt Chloride ◽

Hypoxia Inducible Factor ◽

Hypoxia Inducible Factor 1Α

Download Full-text

Evitar (l-Alanyl-l-Glutamine) Regulates Key Signaling Molecules in the Pathogenesis of Postoperative Tissue Fibrosis

Reproductive Sciences ◽

10.1177/1933719118789511 ◽

2018 ◽

Vol 26 (6) ◽

pp. 724-733 ◽

Cited By ~ 1

Author(s):

Lynne M. Robertson ◽

Nicole M. Fletcher ◽

Michael P. Diamond ◽

Ghassan M. Saed

Keyword(s):

Cellular Response ◽

Type I Collagen ◽

Primary Cultures ◽

Hypoxia Inducible Factor ◽

Enzyme Linked Immunosorbent Assay ◽

Type I ◽

Dependent Manner ◽

Tissue Fibrosis ◽

Hypoxia Inducible Factor 1Α ◽

Episodic Hypoxia

Aims:Hypoxia and the resulting oxidative stress play a major role in postoperative tissue fibrosis. The objective of this study was to determine the effect of l-alanyl-l-glutamine (Ala-Gln) on key markers of postoperative tissue fibrosis: hypoxia-inducible factor (HIF) 1α and type I collagen.Methods:Primary cultures of human normal peritoneal fibroblasts (NPF) established from normal peritoneal tissue were treated with increasing doses of Ala-Gln (0, 1, 2, or 10 mM) with hypoxia ([2% O2] 0-48 hours; continuous hypoxia) or after hypoxia (0.5, 1, 2, 4 hours) and restoration of normoxia (episodic hypoxia) with immediate treatment with Ala-Gln. Hypoxia-inducible factor 1α and type 1 collagen levels were determined by enzyme-linked immunosorbent assay. Data were analyzed with 1-way analysis of variance followed by Tukey tests with Bonferroni correction.Results:Hypoxia-inducible factor 1α and type I collagen levels increased in untreated controls by 3- to 4-fold in response to continuous and episodic hypoxia in human NPF. Under continuous hypoxia, HIF-1α and type I collagen levels were suppressed by Ala-Gln in a dose-dependent manner. l-alanyl-l-glutamine treatment after episodic hypoxia also suppressed HIF-1α and type I collagen levels for up to 24 hours for all doses and up to 48 hours at the highest dose, regardless of exposure time to hypoxia.Conclusions:l-alanyl-l-glutamine significantly suppressed hypoxia-induced levels of key tissue fibrosis (adhesion) phenotype markers under conditions of continuous as well as episodic hypoxia in vitro. This effect of glutamine on molecular events involved in the cellular response to insult or injury suggests potential therapeutic value for glutamine in the prevention of postoperative tissue fibrosis.

Download Full-text