Freud-1: A neuronal calcium-regulated repressor of the 5-HT1A receptor gene.
Altered regulation of 5-HT1A receptors is implicated in mood disorders such as anxiety and major depression. To provide insight into its transcriptional regulation, we previously identified a novel DNA element [14 bp 5'-repressor element (FRE)] of the 5-HT1A receptor gene that mediates repression in neuronal and non-neuronal cells (Ou et al., 2000). We have now cloned a novel DNA binding protein [five' repressor element under dual repression binding protein-1 (Freud-1)] that binds to FRE to mediate repression of the 5-HT1A receptor or heterologous promoters. Freud-1 is evolutionarily conserved and contains two DM-14 basic repeats, a predicted helix-loop-helix DNA binding domain, and a protein kinase C conserved region 2 (C2)/calcium-dependent lipid binding (CalB) calcium/phospholipid binding domain. An intact CalB domain was required for Freud-1-mediated repression. In serotonergic raphe cells, overexpression of Freud-1 repressed the 5-HT1A promoter and decreased 5-HT1A receptor protein levels, whereas transfection of antisense to Freud-1 derepressed the 5-HT1A gene and increased 5-HT1A receptor protein expression. Calcium-dependent signaling blocked Freud-1-FRE binding and derepressed the 5-HT1A promoter. Treatment with inhibitors of calmodulin or CAM-dependent protein kinase reversed calcium-mediated inhibition of Freud-1. Freud-1 RNA and protein were present in raphe nuclei, hippocampus, cortex, and hypothalamus, and Freud-1 protein was colocalized with 5-HT1A receptors, suggesting its importance in regulating 5-HT1A receptors in vivo. Thus, Freud-1 represents a novel calcium-regulated repressor that negatively regulates basal 5-HT1A receptor expression in neurons and may play a role in the altered regulation of 5-HT1A receptors associated with anxiety or major depression.
Ou
Xiao-Ming
XM
Ottawa Health Research Institute, Neuroscience, University of Ottawa, Ottawa, Ontario, Canada K1H-8M5.
Lemonde
Sylvie
S
Jafar-Nejad
Hamed
H
Bown
Christopher D
CD
Goto
Aya
A
Rogaeva
Anastasia
A
Albert
Paul R
PR
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D002460:Cell Line; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D020868:Gene Silencing / Q000187:drug effects; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000096:biosynthesis; D011903:Raphe Nuclei / Q000378:metabolism; D051381:Rats; D011985:Receptors, Serotonin / Q000096:biosynthesis / Q000235:genetics*; D044263:Receptors, Serotonin, 5-HT1; D012097:Repressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D037941:Silencer Elements, Transcriptional
C476534:Cc2d1a protein, rat; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012097:Repressor Proteins; D000255:Adenosine Triphosphate; D002118:Calcium