Transcriptional interaction of an estrogen receptor splice variant and ErbB4 suggests convergence in gene susceptibility pathways in schizophrenia.
Mounting evidence from clinical and basic research suggests that estrogen signaling may be altered in the brains of people with schizophrenia. Previously, we found that DNA sequence variation in the estrogen receptor (ER) alpha gene, lower ERalpha mRNA levels, and/or blunted ERalpha signaling is associated with schizophrenia. In this study, we asked whether the naturally occurring truncated ERalpha isoform, Delta7, which acts as a dominant negative, can attenuate gene expression induced by the wild-type (WT) receptor in an estrogen-dependent manner in neuronal (SHSY5Y) and non-neuronal (CHOK1 and HeLa) cells. In addition, we determined the extent to which ERalpha interacts with NRG1-ErbB4, a leading schizophrenia susceptibility pathway. Reductions in the transcriptionally active form of ErbB4 comprising the intracytoplasmic domain (ErbB4-ICD) have been found in schizophrenia, and we hypothesized that ERalpha and ErbB4 may converge to control gene expression. In the present study, we show that truncated Delta7-ERalpha attenuates WT-ERalpha-driven gene expression across a wide range of estrogen concentrations in cells that express functional ERalpha at base line or upon co-transfection of full-length ERalpha. Furthermore, we find that ErbB4-ICD can potentiate the transcriptional activity of WT-ERalpha at EREs in two cell lines and that this potentiation effect is abolished by the presence of Delta7-ERalpha. Immunofluorescence microscopy revealed nuclear co-localization of WT-ERalpha, Delta7-ERalpha, and ErbB4-ICD, whereas immunoprecipitation assays showed direct interaction. Our findings demonstrate convergence between ERalpha and ErbB4-ICD in the transcriptional control of ERalpha-target gene expression and suggest that this may represent a convergent pathway that may be disrupted in schizophrenia.
Schizophrenia Research Institute, Sydney, New South Wales 2052, Australia.
Jenny
J
Wong
Cynthia Shannon
CS
Weickert
D017398:Alternative Splicing; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D066246:ErbB Receptors / Q000235:genetics* / Q000502:physiology*; D004958:Estradiol / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; D066247:Receptor, ErbB-4; D011960:Receptors, Estrogen / Q000235:genetics* / Q000502:physiology*; D012559:Schizophrenia / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
D012333:RNA, Messenger; D011960:Receptors, Estrogen; D004958:Estradiol; C587689:ERBB4 protein, human; D066246:ErbB Receptors; D066247:Receptor, ErbB-4