Sustained CREB Phosphorylation Is Associated with Neuritogenic Prostanoid Signaling in NSC-34 Cells

Neuritogenesis is essential for neuronal development and circuit formation. Although cAMP signaling downstream of Gs-coupled receptors is considered pro-neuritogenic, activation of these Gs-coupled receptors can produce divergent cellular outcomes. We previously showed that prostaglandin E2 (PGE2) induces neurite outgrowth in NSC-34 motor neuron-like cells predominantly through Gs-coupled E-prostanoid receptor 2 (EP2) signaling. The I-prostanoid receptor (IP) is also Gs-coupled, but whether its ligand PGI2 elicits neuritogenesis remains unclear. Here, we compare the neuritogenic and signaling responses to PGE2 and PGI2 in NSC-34 cells. PGE2 and the EP2 agonist butaprost increased the proportion of neurite-bearing cells, whereas PGI2 and the IP agonist beraprost had no effect. PGI2 and PGE2 induced comparable cAMP accumulation and protein kinase A substrate phosphorylation, and elicited peak cAMP response element binding protein (CREB) phosphorylation at 1 h. However, only PGE2 maintained significant CREB phosphorylation at 3–6 h. RNA sequencing at 4 h revealed broadly concordant transcriptional responses, while direct comparison identified Fst as the only gene expressed at higher levels under PGE2 than under PGI2. These findings suggest that the temporal profile of CREB phosphorylation, rather than the magnitude of early cAMP-PKA signaling, may be associated with differences in neuritogenic outcomes of Gs-coupled prostanoid signaling.