title: Orphan nuclear receptor TLX recruits histone deacetylases to repress transcription and regulate neural stem cell proliferation.
abstract: TLX is a transcription factor that is essential for neural stem cell proliferation and self-renewal. However, the molecular mechanism of TLX-mediated neural stem cell proliferation and self-renewal is largely unknown. We show here that TLX recruits histone deacetylases (HDACs) to its downstream target genes to repress their transcription, which in turn regulates neural stem cell proliferation. TLX interacts with HDAC3 and HDAC5 in neural stem cells. The HDAC5-interaction domain was mapped to TLX residues 359-385, which contains a conserved nuclear receptor-coregulator interaction motif IXXLL. Both HDAC3 and HDAC5 have been shown to be recruited to the promoters of TLX target genes along with TLX in neural stem cells. Recruitment of HDACs led to transcriptional repression of TLX target genes, the cyclin-dependent kinase inhibitor, p21(CIP1/WAF1)(p21), and the tumor suppressor gene, pten. Either inhibition of HDAC activity or knockdown of HDAC expression led to marked induction of p21 and pten gene expression and dramatically reduced neural stem cell proliferation, suggesting that the TLX-interacting HDACs play an important role in neural stem cell proliferation. Moreover, expression of a TLX peptide containing the minimal HDAC5 interaction domain disrupted the TLX-HDAC5 interaction. Disruption of this interaction led to significant induction of p21 and pten gene expression and to dramatic inhibition of neural stem cell proliferation. Taken together, these findings demonstrate a mechanism for neural stem cell proliferation through transcriptional repression of p21 and pten gene expression by TLX-HDAC interactions.
authors.affiliation: Neuroscience Division, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Sun
authors.forename: Ruth T
authors.initials: RT
authors.lastname: Yu
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Evans
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Shi
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology*; D005786:Gene Expression Regulation; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D057093:Orphan Nuclear Receptors; D051059:PTEN Phosphohydrolase / Q000378:metabolism / Q000502:physiology*; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013234:Stem Cells / Q000166:cytology*; D014158:Transcription, Genetic
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C088601:NR2E1 protein, human; D057093:Orphan Nuclear Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D051059:PTEN Phosphohydrolase; D006655:Histone Deacetylases