Aromatic Hydrocarbon Receptor Interaction with the Retinoblastoma Protein Potentiates Repression of E2F-dependent Transcription and Cell Cycle Arrest

作者：Alvaro Puga, Sonya Barnes, Timothy P. Dalton, Ching‐yi Chang, Erik S. Knudsen, Michael A. Maier · 发表于：Journal of Biological Chemistry · 年份：2000 · DOI：10.1074/jbc.275.4.2943 · 被引用次数：314 · 研究领域：Toxic Organic Pollutants Impact、Retinoids in leukemia and cellular processes、Cancer-related Molecular Pathways

Polyhalogenated aromatic hydrocarbons, of which 2,3,7, 8-tetrachloro-p-dioxin (TCDD) is the prototype compound, elicit a variety of toxic, teratogenic, and carcinogenic responses in exposed animals and in humans. In cultured cells, TCDD shows marked effects on the regulation of cell cycle progression, including thymocyte apoptosis, induction of keratinocyte proliferation and terminal differentiation, and inhibition of estrogen-dependent proliferation in breast cancer cells. The presence of an LXCXE domain in the dioxin aromatic hydrocarbon receptor (AHR), suggested that the effects of TCDD on cell cycle regulation might be mediated by protein-protein interactions between AHR and the retinoblastoma protein (RB). Using the yeast two-hybrid system, AHR and RB were in fact shown to bind to each other. In vitro pull-down experiments with truncated AHR peptides indicated that at least two separate AHR domains form independent complexes with hypophosphorylated RB. Coimmunoprecipitation of whole cell lysates from human breast carcinoma MCF-7 cells, which express both proteins endogenously, revealed that AHR associates with RB in vivo only after receptor transformation and nuclear translocation. However, the AHR nuclear translocator and transcriptional heterodimerization partner, is not required for (nor is it a part of) the AHR.RB complexes detected in vitro. Ectopic expression of AHR and RB in human osteosarcoma SAOS-2 cells, which lack endogenous expression of both proteins, showed...