Emerging Roles for PKC Isoforms in Immune Cell Function

Negative roles for PKC isoforms in B lymphocyte signaling. B cell receptor (BCR) engagement leads to a cascade of signaling events, eventually leading to the activation of the B cell. Specific PKC isoforms that are activated by the BCR can inhibit B cell signaling. Although PKCβ and PKCμ function in negative feedback loops to inhibit the upstream activators Btk (itself activated bt the tyrosine kinase Lyn) and Syk, respectively, PKCδ may function to inhibit the NF-IL6 transcription factor. BLNK, B cell linker protein; Syk, a 72-kDa protein tyrosine kinase highly expressed in B cells; Btk, Bruton’s tyrosine kinase; DAG, diacylglycerol; NF-IL6, nuclear factor for interleukin-6 expression.