Type 1 diabetes (T1D) may result from a breakdown in peripheral tolerance that is partially controlled by peripheral tissue antigen (PTA) expression in lymph nodes. Here we show that the transcriptional regulator deformed epidermal autoregulatory factor 1 (Deaf1) controls PTA gene expression in the pancreatic lymph nodes (PLN). The expression of canonical Deaf1 was reduced, while that of an alternatively spliced variant was increased during the onset of destructive insulitis in the PLN of NOD mice. An equivalent variant Deaf1 isoform was identified in the PLN of T1D patients. Both NOD and human Deaf1 variant isoforms suppressed PTA expression by inhibiting the transcriptional activity of canonical Deaf1. Reduced PTA expression resulting from the alternative splicing of Deaf1 may contribute to T1D pathogenesis.

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The serotonin-1A (5-HT 1A ) receptor is the primary somatodendritic autoreceptor that inhibits the activity of serotonergic raphe neurons and is also expressed in nonserotonergic cortical and limbic neurons. Alterations in 5-HT 1A receptor levels are implicated in mood disorders, and a functional C(-1019)G 5-HT 1A promoter polymorphism has been associated with depression, suicide, and panic disorder. We examined the cell-specific activity of identified transcription factors, human nuclear deformed epidermal autoregulatory factor-1 (DEAF-1)-related (

Background: Dysregulation of 5-HT1A receptors is associated with depression, but the transcriptional mechanisms are unclear. Results: Deaf-1 binds the 5-HT1A promoter, and loss of Deaf-1 results in altered expression of 5-HT1A receptors and reduced serotonin levels. Conclusion: Deaf-1 is a key regulator of 5-HT1A expression in vivo that is affected by a promoter polymorphism prevalent in human depression. Significance: Understanding transcriptional regulators of serotonin could lead to improved antidepressant strategies.

A variety of studies have documented alterations in 5-HT1A receptor binding sites in the brain of subjects with major depressive disorder (MDD). The recently identified transcription factor, nuclear deformed epidermal autoregulatory factor (NUDR/Deaf-1) has been shown to function as a transcriptional modulator of the human 5-HT1A receptor gene. The present study was undertaken to document the regional and cellular localization of NUDR in the human prefrontal cortex and to examine the levels of NUDR and 5-HT1A receptor protein in prefrontal cortex of female and male depressed and control subjects. NUDR immunoreactivity was present in neurons and glia across cortical layers and was co-localized with 5-HT1A receptor immunoreactive neurons. NUDR immunoreactivity as measured by Western blot was significantly decreased in the prefrontal cortex of female depressed subjects (42%, p=0.02) and unchanged in male depressed subjects relative to gender-matched control subjects. Similarly, 5-HT1A receptor protein level was significantly reduced in the prefrontal cortex of female depressed subjects (46%, p=0.03) and unchanged in male depressed subjects compared to gender-matched control subjects. Reduced protein expression of NUDR in the prefrontal cortex of female subjects with MDD may reflect a functional alteration in this transcription factor, which may contribute to the decrease in 5-HT1A receptors observed in the same female subjects with MDD. In addition, the gender-specific alterations in cortical NUDR and 5-HT1A receptor proteins could represent an underlying biological mechanism associated with the higher incidence of depression in women.

J. Neurochem. (2011) 116, 1066–1076. 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.

Alterations in brain serotonin levels are implicated in major depression and are regulated by tryptophan hydroxylase-2 (TPH2). To study its regulation, we measured TPH2 RNA by quantitative RT-PCR in differentiated serotonergic rat raphe RN46A and GH4C1 pituitary cells, which express TPH2. Upon calcium mobilization using KCl (40 mmol/L), TPH2 RNA was rapidly (1 h) and strongly (> 10-fold) induced in differentiated RN46A cells, but not in GH4C1 cells. This effect was blocked by actinomycin D, implicating transcriptional activation. Similarly, calcium ionophore ionomycin induced TPH2 RNA by threefold in RN46A cells. To address the promoter sites involved, the transcription start site was identified and a series of TATA-containing TPH2 promoter-luciferase constructs were analyzed. In differentiated RN46A cells, the TPH2 promoter was induced 2.5-fold by ionomycin, similar to its action on TPH2 RNA. By contrast, ionomycin had no effect on TPH2 promoter activity in GH4C1 cells or TPH2-negative L6 myoblasts. Ionomycin sensitivity was localized to within 88 bp of the start site, containing putative CCATT-enhancer binding protein element, activator protein-1 and -2 (AP-1, AP-2) elements. These results are the first to identify calcium-mediated regulation of the proximal TPH2 promoter as critical for cellspecific TPH2 expression. Keywords: calcium, promoter, RN46A, serotonin, transcription, tryptophan hydroxylase. The serotonin system of the CNS modulates numerous physiological functions including regulation of the stress response and behavioral traits, such as aggression, fear, and anxiety (Lesch 2005;Wrase et al. 2006). Accordingly, dysregulation of serotonergic neurotransmission is implicated as a contributing cause of a number of psychiatric and endocrine disorders. Proper serotonergic function requires adequate production of serotonin or 5-hydroxytryptamine (5-HT), which is largely controlled by the activity of tryptophan hydroxylase (TPH; tryptophan 5-monooxygenase, EC 1.14.16.4), the enzyme catalyzing the rate-limiting step in 5-HT biosynthesis (Lovenberg et al. 1967). Interestingly, two genes with distinct patterns of expression encode different TPH isoforms, namely TPH1 and TPH2. In nonneuronal serotonergic cells, only TPH1 is expressed, while serotonergic neurons express predominantly TPH2 and trace amounts of TPH1 (Côté et al. 2003;Walther et al. 2003;Patel et al. 2004). TPH2 appears to control serotonin synthesis in the adult CNS (Zhang et al. 2004) and increasing evidence supports its clinical relevance. For example, a point mutation that reduces TPH2 activity has been associated with major depression, although this mutation is rare (Blakely 2005;Zhang et al. 2005). In addition, other common polymorphisms in the TPH2 gene promoter or introns have been associated with major depression (Zill et al. 2004b), suicidal behavior (Zill et al. 2004a), and attention deficit-hyperactivity disorder (Walitza et al. 2005). In some cases, these polymorphisms were located in the 5¢-flanking region, suggesting that alt...

Although they have distinct functions, the signaling of dopamine-D(2) receptor short and long isoforms (D(2)S and D(2)L) is virtually identical. We compared inhibitory regulation of extracellular signal-regulated kinases (ERK1/2) in GH4 pituitary cells separately transfected with these isoforms. Activation of rat or human dopamine-D(2)S, muscarinic or somatostatin receptors inhibited thyrotropin-releasing hormone-induced ERK1/2 phosphorylation, while the D(2)L receptor failed to inhibit this response. In order to address the structural basis for the differential signaling of D(2)S and D(2)L receptors, we examined the D(2)L-SS mutant, in which a protein kinase C (PKC) pseudosubstrate site that is present in the D(2)L but not D(2)S receptor was converted to a consensus PKC site. In transfected GH4 cells, the D(2)L-SS mutant inhibited thyrotropin-releasing hormone-induced ERK1/2 phosphorylation almost as strongly as the D(2)S receptor. A D(2)S-triple mutant that eliminates PKC sites involved in D(2)S receptor desensitization also inhibited ERK1/2 activation. Similarly, in striatal cultures, the D(2)-selective agonist quinpirole inhibited potassium-stimulated ERK1/2 phosphorylation, indicating the presence of this pathway in neurons. In conclusion, the D(2)S and D(2)L receptors differ in inhibitory signaling to ERK1/2 due to specific residues in the D(2)L receptor alternatively spliced domain, which may account for differences in their function in vivo.