The role of MARCKS in mast cell regulated exocytosis.

摘要

MARCKS is implicated as a critical regulator of regulated exocytosis. We studied the role of MARCKS in mast cell regulated exocytosis by comparing the secretion of embryonic hepatic-derived WT and MARCKS-deficient mast cells. Mast cells in suspension showed no secretory differences, however, adherent MARCKS-deficient cells demonstrated enhanced secretion and accelerated release of secretory cargo compared to WT. Surprisingly, application of purported MARCKS inhibitory peptides showed no MARCKS-specific inhibition. Thus, while MARCKS is not essential for mast cell regulated exocytosis, it does negatively modulate secretion.;In a separate study, conserved regions of MARCKS were tested for their necessity in the subcellular targeting of MARCKS from the PM to the cytosol, believed to be crucial for its multiple functions. We confirmed this movement using live cell imaging of HEK293 cells transfected with full-length MARCKS constructs. Notably, phosphorylated MARCKS associated with cytosolic membranes, and only myristoylation and PKC phosphorylation affected the translocation process.