Transrepressive function of TLX requires the histone demethylase, LSD1

Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan; Universitäts-Frauenklinik und Zentrum für Klinische Forschung, Klinikum der Universität Freiburg, Breisacherstrasse 66, 79106 Freiburg, Germany; ERATO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan

^* To whom correspondence should be addressed. Email: uskato{at}mail.ecc.u-tokyo.ac.jp.

	Abstract

TLX is an orphan nuclear receptor (also called NR2E1) which regulates the expression of target genes by functioning as a constitutive transrepressor. The physiological significance of TLX in the cytodifferentiation of neural cells in the brain is known. However, the co-repressors supporting the transrepressive function of TLX have yet to be identified. In this report, Y79 retinoblastoma cells were subjected to biochemical techniques to purify proteins which interact with TLX, and we identified LSD1 (also called KDM1) which appears to form a complex with CoREST and HDAC1. LSD1 interacted with TLX directly through its SWIRM and amine oxidase domains. LSD1 potentiated the transrepressive function of TLX through its histone demethylase activity as determined by a luciferase assay using a genomically-integrated reporter gene. LSD1 and TLX were recruited to a TLX binding site in the PTEN gene promoter, accompanied with the demethylation of H3K4me2 and deacetylation of H3. Knock-down of either TLX or LSD1 derepressed expression of the endogenous PTEN gene, and inhibited cell proliferation of Y79 cells. Thus, the present study suggests that LSD1 is a prime co-repressor for TLX.