title: Region-specific regulation of 5-HT1A receptor expression by Pet-1-dependent mechanisms in vivo.
abstract: Serotonin (5-hydroxytryptamine, 5-HT) neurotransmission is negatively regulated by 5-HT1A autoreceptors on raphe neurons, and is implicated in mood disorders. Pet-1/FEV is an ETS transcription factor expressed exclusively in serotonergic neurons and is essential for serotonergic differentiation, although its regulation of 5-HT receptors has not yet been studied. Here, we show by electrophoretic mobility shift assay that recombinant human Pet-1/FEV binds directly to multiple Pet-1 elements of the human 5-HT1A receptor promoter to enhance its transcriptional activity. In luciferase reporter assays, mutational analysis indicated that while several sites contribute, the Pet-1 site at -1406 bp had the greatest effect on 5-HT1A promoter activity. To address the effect of Pet-1 on 5-HT1A receptor regulation in vivo, we compared the expression of 5-HT1A receptor RNA and protein in Pet-1 null and wild-type littermate mice. In the raphe nuclei of Pet-1-/- mice tryptophan hydroxylase 2 (TPH2) RNA, and 5-HT and TPH immunostaining were greatly reduced, indicating a deficit in 5-HT production. Raphe 5-HT1A RNA and protein levels were also reduced in Pet-1-deficient mice, consistent with an absence of Pet-1-mediated transcriptional enhancement of 5-HT1A autoreceptors in serotonergic neurons. Interestingly, 5-HT1A receptor expression was up-regulated in the hippocampus, but down-regulated in the striatum and cortex. These data indicate that, in addition to transcriptional regulation by Pet-1 in raphe neurons, 5-HT1A receptor expression is regulated indirectly by alterations in 5-HT neurotransmission in a region-specific manner that together may contribute to the aggressive/anxiety phenotype observed in Pet-1 null mice.
authors.affiliation: Ottawa Hospital Research Institute (Neuroscience), University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Kirsten X
authors.initials: KX
authors.lastname: Jacobsen
authors.forename: Margaret
authors.initials: M
authors.lastname: Czesak
authors.forename: Mariam
authors.initials: M
authors.lastname: Deria
authors.forename: Brice
authors.initials: B
authors.lastname: Le François
authors.forename: Paul R
authors.initials: PR
authors.lastname: Albert
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009447:Neuroblastoma; D011401:Promoter Regions, Genetic / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D044282:Receptor, Serotonin, 5-HT1A / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000172:deficiency / Q000502:physiology*; D014162:Transfection / Q000379:methods; D014365:Tryptophan Hydroxylase / Q000235:genetics / Q000378:metabolism
chemical_list: C484684:Fev protein, mouse; D012333:RNA, Messenger; D014157:Transcription Factors; D044282:Receptor, Serotonin, 5-HT1A; D014365:Tryptophan Hydroxylase