Ca2+ influx and protein scaffolding via TRPC3 sustain PKCβ and ERK activation in B cells

Abstract

Ca2+ signaling mediated by phospholipase C that produces inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] and diacylglycerol (DAG) controls lymphocyte activation. In contrast to store-operated Ca2+ entry activated by Ins(1,4,5)P3-induced Ca2+ release from endoplasmic reticulum, the importance of DAG-activated Ca2+ entry remains elusive. Here, we describe the physiological role of DAG-activated Ca2+ entry channels in B-cell receptor (BCR) signaling. In avian DT40 B cells, deficiency of transient receptor potential TRPC3 at the plasma membrane (PM) impaired DAG-activated cation currents and, upon BCR stimulation, the sustained translocation to the PM of protein kinase Cβ (PKCβ) that activated extracellular signal-regulated kinase (ERK). Notably, TRPC3 showed direct association with PKCβ that maintained localization of PKCβ at the PM. Thus, TRPC3 functions as both a Ca2+-permeable channel and a protein scaffold at the PM for downstream PKCβ activation in B cells.