PT - JOURNAL ARTICLE AU - Sunny Zhihong Jiang AU - Wenqin Xu AU - Andrew C. Emery AU - Charles R. Gerfen AU - Maribeth V. Eiden AU - Lee E. Eiden TI - NCS-Rapgef2, the Protein Product of the Neuronal <em>Rapgef2</em> Gene, Is a Specific Activator of D1 Dopamine Receptor-Dependent ERK Phosphorylation in Mouse Brain. AID - 10.1523/ENEURO.0248-17.2017 DP - 2017 Sep 11 TA - eneuro PG - ENEURO.0248-17.2017 4099 - http://www.eneuro.org/content/early/2017/09/11/ENEURO.0248-17.2017.short 4100 - http://www.eneuro.org/content/early/2017/09/11/ENEURO.0248-17.2017.full AB - The neuritogenic cyclic AMP sensor (NCS), encoded by the Rapgef2 gene, links cyclic AMP elevation to activation of extracellular signal-regulated kinase (ERK) in neurons and neuroendocrine cells. Transducing human embryonic kidney (HEK) 293 cells, which do not express Rapgef2 protein or respond to cAMP with ERK phosphorylation, with a vector encoding a Rapgef2 cDNA reconstituted cAMP-dependent ERK activation. Mutation of a single residue in the cyclic nucleotide binding domain (CNBD) conserved across cAMP binding proteins abrogated cAMP-ERK coupling, while deletion of the CNBD altogether resulted in constitutive ERK activation. Two types of mRNA are transcribed from Rapgef2 in vivo. Rapgef2 protein expression was limited to tissues, i.e. neuronal and endocrine, expressing the second type of mRNA, initiated exclusively from an alternative first exon called here exon 1’, and an alternative 5’ protein sequence leader fused to a common remaining open reading frame, which is termed here NCS-Rapgef2. In the male mouse brain, NCS-Rapgef2 is prominently expressed in corticolimbic excitatory neurons, and striatal medium spiny neurons (MSNs). Rapgef2-dependent ERK activation by the dopamine D1 agonist SKF81297 occurred in neuroendocrine NS-1 cells expressing the human D1 receptor, and was abolished by deletion of Rapgef2. Corticolimbic (e.g. dentate gyrus, basolateral amygdala) ERK phosphorylation induced by SKF81297 was significantly attenuated in CamK2α-Cre+/-; Rapgef2cko/cko male mice. ERK phosphorylation in NAc MSNs induced by treatment with SKF81297, or the psychostimulants cocaine or amphetamine, was abolished in male Rapgef2cko/cko mice with NAc NCS-Rapgef2-depleting AAV-Synapsin-Cre injections. We conclude that D1-dependent ERK phosphorylation in mouse brain requires NCS-Rapgef2 expression.Significance Statement Our report demonstrates that the cyclic AMP-regulated guanine nucleotide exchange factor NCS-Rapgef2 is required for D1 receptor-dependent dopaminergic activation of the MAP kinase ERK in neuroendocrine cells in culture, and in dopamine-innervated, D1 receptor-expressing regions of the adult mouse brain, including the hippocampus, amygdala and ventral striatum. NCS-Rapgef2 is the protein product of a neuronal/endocrine-specific set of messenger RNAs transcribed from an alternative promoter within the Rapgef2 gene locus in both rodents and humans. NCS-Rapgef2 expression in nucleus accumbens is required for ERK activation in this dopaminergic reward center by the psychostimulants cocaine or amphetamine, suggesting a role for NCS-Rapgef2 in the mechanisms of action of these drugs of abuse.