Interleukin-1β activates an Src family kinase to stimulate the plasma membrane Ca²⁺ pump in hippocampal neurons

The plasma membrane Ca²⁺ ATPase (PMCA) plays a major role in clearing Ca²⁺ from the neuronal cytoplasm. The cytoplasmic Ca²⁺ clearance rate affects neuronal excitability, synaptic plasticity, and neurotransmission. Here, we examined the modulation of PMCA activity by PTKs in hippocampal neurons. PMCA-mediated Ca²⁺ clearance slowed in the presence of pyrazolopyrimidine 2, an inhibitor of Src family kinases (SFKs), and accelerated in the presence of C2-ceramide, an activator of PTKs. Ca²⁺ clearance kinetics were attenuated in cells expressing a dominant-negative Src mutant, suggesting that the pump is tonically stimulated by a PTK. Tonic stimulation was reduced in hippocampal neurons expressing short hairpin (sh)RNA directed to mRNA for Yes. shRNA-mediated knockdown of PMCA isoform 1 (PMCA1) removed tonic stimulation of Ca²⁺ clearance, indicating that the kinase stimulates PMCA1. IL-1β accelerated Ca²⁺ clearance in a manner blocked by an IL-1β receptor antagonist or by an inhibitor of neutral sphingomyelinase, the enzyme that produces ceramide. Thus IL-1β activates an SFK to stimulate the plasma membrane Ca²⁺ pump, decreasing the duration of Ca²⁺ transients in hippocampal neurons.