Search

We report here that PLC-γ isoforms are required for agonist-induced Ca2+ entry (ACE). Overexpressed wild-type PLC-γ1 or a lipase-inactive mutant PLC-γ1 each augmented ACE in PC12 cells, while a deletion mutant lacking the region containing the SH3 domain of PLC-γ1 was ineffective. RNA interference to deplete either PLC-γ1 or PLC-γ2 in PC12 and A7r5 cells inhibited ACE. In DT40 B lymphocytes expressing only PLC-γ2, overexpressed muscarinic M5 receptors (M5R) activated ACE. Using DT40 PLC-γ2 knockout cells, M5R stimulation of ER Ca2+ store release was unaffected, but ACE was abolished. Normal ACE was restored by transient expression of PLC-γ2 or a lipase-inactive PLC-γ2 mutant. The results indicate a lipase-independent role of PLC-γ in the physiological agonist-induced activation of Ca2+ entry. [Copyright &y& Elsevier]

Examines the coupling mechanism of endoplasmic reticulum (ER) Ca2+ stores and plasma membrane (PM) store-operated Ca2+ (SOC) entry channels. Role of Ca2+ signals in cellular functions; Modification of actin cytoskeleton; Trafficking model involving ER-PM interaction; Secretion-based coupling model for SOC activation.

We report here that PLC-gamma isoforms are required for agonist-induced Ca2+ entry (ACE). Overexpressed wild-type PLC-gamma1 or a lipase-inactive mutant PLC-gamma1 each augmented ACE in PC12 cells, while a deletion mutant lacking the region containing the SH3 domain of PLC-gamma1 was ineffective. RNA interference to deplete either PLC-gamma1 or PLC-gamma2 in PC12 and A7r5 cells inhibited ACE. In DT40 B lymphocytes expressing only PLC-gamma2, overexpressed muscarinic M5 receptors (M5R) activated ACE. Using DT40 PLC-gamma2 knockout cells, M5R stimulation of ER Ca2+ store release was unaffected, but ACE was abolished. Normal ACE was restored by transient expression of PLC-gamma2 or a lipase-inactive PLC-gamma2 mutant. The results indicate a lipase-independent role of PLC-gamma in the physiological agonist-induced activation of Ca2+ entry.