Increased Serotonin-1A (5-HT1A) Autoreceptor Expression and Reduced Raphe Serotonin Levels in Deformed Epidermal Autoregulatory Factor-1 (Deaf-1) Gene Knock-out Mice

• Published in: The Journal of biological chemistry 2012-02, Vol.287 (9), p.6615-6627
• Main Authors: Czesak, Margaret, Le François, Brice, Millar, Anne M., Deria, Mariam, Daigle, Mireille, Visvader, Jane E., Anisman, Hymie, Albert, Paul R.
• Format: Article
• Language: English
• Subjects: 7-Helix Receptor; Animals; Autoreceptors - genetics; Autoreceptors - metabolism; Depression; Depressive Disorder - metabolism; Depressive Disorder - physiopathology; DNA-Binding Proteins; Female; Fluorescent Antibody Technique; Male; Mice; Mice, 129 Strain; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Knockout; Molecular Bases of Disease; Polymorphism, Genetic - genetics; Promoter Regions, Genetic - genetics; Promoters; Raphe Nuclei - physiology; Receptor Regulation; Receptor, Serotonin, 5-HT1A - genetics; Receptor, Serotonin, 5-HT1A - metabolism; RNA, Messenger - metabolism; Serotonin; Serotonin - metabolism; Transcription Factors; Transcription Factors - genetics; Transcription Factors - metabolism; Tryptophan Hydroxylase - genetics; Tryptophan Hydroxylase - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111.293027

Altered regulation of the serotonin-1A (5-HT1A) receptor gene is implicated in major depression and mood disorders. The functional human 5-HT1A C(−1019)G promoter polymorphism (rs6295), which prevents the binding of Deaf-1/NUDR leading to dysregulation of the receptor, has been associated with major depression. In cell models Deaf-1 displays dual activity, repressing 5-HT1A autoreceptor expression in serotonergic raphe cells while enhancing postsynaptic 5-HT1A heteroreceptor expression in nonserotonergic neurons. A functional Deaf-1 binding site on the mouse 5-HT1A promoter was recognized by Deaf-1 in vitro and in vivo and mediated dual activity of Deaf-1 on 5-HT1A gene transcription. To address regulation by Deaf-1 in vivo, Deaf-1 knock-out mice bred to a C57BL/6 background were compared with wild-type siblings for changes in 5-HT1A RNA and protein by quantitative RT-PCR, in situ hybridization, and immunofluorescence. In the dorsal raphe, Deaf-1 knock-out mice displayed increased 5-HT1A mRNA, protein, and 5-HT1A-positive cell counts but reduced 5-HT levels, whereas other serotonergic markers, such as tryptophan hydroxylase (TPH)- or 5-HT-positive cells and TPH2 RNA levels, were unchanged. By contrast, 5-HT1A mRNA and 5-HT1A-positive cells were reduced in the frontal cortex of Deaf-1-null mice, with no significant change in hippocampal 5-HT1A RNA, protein, or cell counts. The region-specific alterations of brain 5-HT1A gene expression and reduced raphe 5-HT content in Deaf-1−/− mice indicate the importance of Deaf-1 in regulation of 5-HT1A gene expression and provide insight into the role of the 5-HT1A G(−1019) allele in reducing serotonergic neurotransmission by derepression of 5-HT1A autoreceptors. Dysregulation of 5-HT1A receptors is associated with depression, but the transcriptional mechanisms are unclear. Deaf-1 binds the 5-HT1A promoter, and loss of Deaf-1 results in altered expression of 5-HT1A receptors and reduced serotonin levels. Deaf-1 is a key regulator of 5-HT1A expression in vivo that is affected by a promoter polymorphism prevalent in human depression. Understanding transcriptional regulators of serotonin could lead to improved antidepressant strategies.