Identification of Tbr-1/CASK complex target genes in neurons

J Neurochem. 2004 Dec;91(6):1483-92. doi: 10.1111/j.1471-4159.2004.02845.x.

Abstract

Tbr-1, a neuron-specific T-box transcription factor, plays a critical role in brain development. Here, we performed a computational search using the non-palindromic T-box binding sequence, namely the non-palindromic T-element, to determine the putative downstream target genes of Tbr-1. More than 20 identified genes containing the non-palindromic T-element in the 5' regulatory region were found expressed in brain. Luciferase reporter assays using cultured hippocampal neurons showed that overexpression of Tbr-1 and CASK-enhanced promoter activities of some of these putative target genes, including NMDAR subunit 2b (NR2b), glycine transporter, interleukin 7 receptor (IL-7R) and OX-2. Among these genes, NR2b promoter responded strongest to overexpression of Tbr-1 and CASK. Deletion of the non-palindromic T-elements from NR2b promoter impaired the induction by Tbr-1 and CASK. We also examined expression of these target genes in Tbr-1 knockout mice, it was found that NR2b expression was consistently downregulated. Similarly, both RNA and protein expression levels of NMDAR subunit 1 (NR1), which also contains the non-palindromic T-elements in its 5' regulatory region, were reduced in Tbr-1 knockout mice. We suggest that Tbr-1/CASK protein complex regulates expression of these downstream target genes and thus modulates neuronal activity and function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport Systems, Neutral / genetics
  • Animals
  • Antigens, CD
  • Antigens, Surface / genetics
  • Base Sequence
  • COS Cells
  • Calcium-Calmodulin-Dependent Protein Kinases / physiology*
  • Cells, Cultured
  • Chlorocebus aethiops
  • DNA-Binding Proteins / physiology*
  • Embryo, Mammalian
  • Gene Expression Regulation*
  • Glycine Plasma Membrane Transport Proteins
  • Guanylate Kinases
  • Hippocampus / cytology
  • Humans
  • Mice
  • Mice, Knockout
  • Molecular Sequence Data
  • Neurons / metabolism*
  • Promoter Regions, Genetic / physiology
  • Rats
  • Receptors, Interleukin-7 / genetics
  • Receptors, N-Methyl-D-Aspartate / genetics

Substances

  • Amino Acid Transport Systems, Neutral
  • Antigens, CD
  • Antigens, Surface
  • DNA-Binding Proteins
  • Glycine Plasma Membrane Transport Proteins
  • NR2B NMDA receptor
  • Receptors, Interleukin-7
  • Receptors, N-Methyl-D-Aspartate
  • Tbr1 protein, mouse
  • CASK kinases
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Guanylate Kinases
  • antigens, CD200