Pleckstrin homology domain of phospholipase C-gamma 1 directly binds to 68-kDa neurofilament light chain

Abstract

Phosphoinositide-specific phospholipase C-γ1 (PLC-γ1) has two pleckstrin homology (PH) domains: an amino-terminal domain (PH1) and a split PH domain (PH2). Here, we show that overlay assay of bovine brain tubulin pool with glutathione-S-transferase (GST)-PLC-γ1 PH domain fusion proteins, followed by matrix-assisted laser-desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), identified 68-kDa neurofilament light chain (NF-L) as a binding protein of amino-terminal PH domain of PLC-γ1. NF-L is known as a component of neuronal intermediate filaments, which are responsible for supporting the structure of myelinated axons in neuron. PLC-γ1 and NF-L colocalized in the neurite in PC12 cells upon nerve growth factor stimulation. In vitro binding assay and immunoprecipitation analysis also showed a specific interaction of both proteins in differentiated PC12 cells. The phosphatidylinositol 4, 5-bisphosphate [PI(4,5)P2] hydrolyzing activity of PLC-γ1 was slightly decreased in the presence of purified NF-L in vitro, suggesting that NF-L inhibits PLC-γ1. Our results suggest that PLC-γ1-associated NF-L sequesters the phospholipid from the PH domain of PLC-γ1.