Transrepressive Function of TLX Requires the Histone Demethylase LSD1

Abstract

TLX is an orphan nuclear receptor (also called NR2E1) that 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 corepressors 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 that interact with TLX, and we identified LSD1 (also called KDM1), which appears to form a complex with CoREST and histone deacetylase 1. 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 by the demethylation of H3K4me2 and deacetylation of H3. Knockdown 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 corepressor for TLX.Nuclear receptors (NRs) are transcriptional regulators that play pivotal roles in a variety of key metabolic and developmental processes (26). NRs constitute a gene superfamily, and NR protein structure is divided into several functional domains. One of the well-characterized domains is a highly conserved DNA-binding domain (DBD), and the other is a moderately conserved ligand-binding domain (LBD). The NR gene superfamily includes both steroid/thyroid hormone receptors and vitamin A/D receptors. The transcriptional function of NRs is regulated by the binding of specific ligands. In addition to the ligand-dependent NRs, there is a subfamily of so-called orphan NRs, the ligands of which have not yet been characterized (10). In the absence of ligand, orphan NRs constitutively activate or suppress transcription (20,49,53).Ligand-dependent transcriptional control by NRs requires a number of positive or negative coregulatory multiprotein complexes, in addition to basic transcription factors (25,35,36,52). These coregulator complexes can be classified into two groups. The first group comprises ATP-dependent chromatin-remodeling complexes (such as the SWI/SNF complex), which reorganize nucleosomal arrays and potentiate the promoter accessibility of NRs (6,18,23,33). The other group consists of histone modifier complexes, which covalently modify histone tails by acetylation, methylation, ubiquitination, or phosphorylation. These modifications lead to transcriptional repression or activation within the chromatin (2, 17, 42). Of these modifications, methylation of histone lysines is generally regarded as the most significant histone modification, as it triggers alterations in chromatin structure (27,37). Methylation of H3K9 leads to chromatin silencing, while H3K4 methylation enhances chromatin activity. A number of histone methyltransferases, e.g.,...

Double PHD Fingers Protein DPF2 Recognizes Acetylated Histones and Suppresses the Function of Estrogen-related Receptor α through Histone Deacetylase 1

“…The other subset of NRs is considered an orphan receptor, as physiologically relevant ligands remain to be identified. Orphan receptors are constitutively active or repressive transcription factors; however, their potency in transcriptional regulation appears to be dependent on cell types and the promoter context (3).…”

“…Nuclear receptors (NRs) 3 play pivotal roles during the development of vertebrates and in diverse physiological events in adults (1,2). NRs constitute a gene superfamily and act as transcription factors.…”

The Orphan Nuclear Receptor TLX/NR2E1 in Neural Stem Cells and Diseases

“…Atrophin1, BCL11A, LSD1 (a histone demethylase), histone deacetylase 3 (HDAC3), and HDAC5 have been reported to interact with Tlx to regulate the expression of target genes [45,54,57,58]. The interactions among TLX, LSD1, and Atrophin1 have been validated in human Y79 retinoblastoma cells [57]. In that study, TLX, LSD1, CoREST, and HDAC1/2 were suggested to form a transrepression complex at the Pten promoter to suppress Pten expression in retinal cells.…”

“…Such temporal and spatial specificity probably depends on other interactive proteins that function together with Tlx (or TLX in humans) to form a transcriptional complex in specific cells at certain developmental stages. Atrophin1, BCL11A, LSD1 (a histone demethylase), histone deacetylase 3 (HDAC3), and HDAC5 have been reported to interact with Tlx to regulate the expression of target genes [45,54,57,58]. The interactions among TLX, LSD1, and Atrophin1 have been validated in human Y79 retinoblastoma cells [57].…”

Jumonji domain-containing protein 3 regulates histone 3 lysine 27 methylation during bovine preimplantation development

“…Histone methylation was considered an irreversible process until the lysine-specific demethylase 1 was discovered in 2004 (21)(22)(23). Later, Jumonji domain-containing (JMJD) proteins with demethylase activity at H3K27 residues were reported (24)(25)(26)(27)(28)(29)(30), including ubiquitously transcribed tetratricopeptide repeat X (UTX) and JMJD3 (also known as "KDM6B").…”