α1-Adrenergic receptor–PKC–Pyk2–Src signaling boosts L-type Ca2+ channel CaV1.2 activity and long-term potentiation in rodents

The cellular mechanisms mediating norepinephrine (NE) functions in brain to result in behaviors are unknown. We identified the L-type Ca 2+ channel (LTCC) Ca V 1.2 as a principal target for G q -coupled α 1 -adrenergic receptors (ARs). α 1 AR signaling increased LTCC activity in hippocampal neurons. This regulation required protein kinase C (PKC)-mediated activation of the tyrosine kinases Pyk2 and, downstream, Src. Pyk2 and Src were associated with Ca V 1.2. In model neuroendocrine PC12 cells, stimulation of PKC induced tyrosine phosphorylation of Ca V 1.2, a modification abrogated by inhibition of Pyk2 and Src. Upregulation of LTCC activity by α 1 AR and formation of a signaling complex with PKC, Pyk2, and Src suggests that Ca V 1.2 is a central conduit for signaling by NE. Indeed, a form of hippocampal long-term potentiation (LTP) in young mice requires both the LTCC and α 1 AR stimulation. Inhibition of Pyk2 and Src blocked this LTP, indicating that enhancement of Ca V 1.2 activity via α 1 AR–Pyk2–Src signaling regulates synaptic strength.