Coronin 1B regulates the TNFα-induced apoptosis of HUVECs by mediating the interaction between TRADD and FADD

Coronin 1B is an actin-binding protein that plays important roles in actin-dependent cellular processes. We previously reported that coronin 1B is involved in vascular endothelial cell growth factor–induced migration of human umbilical vein endothelial cells (HUVECs). However, the role of coronin 1B in tumor necrosis factor alpha (TNFα)-induced endothelial cell apoptosis remained unknown. In this study, we investigated whether coronin 1B affects TNFα-induced HUVEC apoptosis and sought to elucidate the mechanism by which coronin 1B regulates this cellular process. Depletion of coronin 1B by siRNA transfection decreased TNFα-induced apoptosis of HUVECs, as determined by MTT, terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase-3 activity assays. Coronin 1B depletion also decreased caspase-8 cleavage via a JNK-independent pathway. Coronin 1B interacted with Fas-associated death domain protein (FADD) in both a plasmid overexpression system in HEK293T cells and at the endogenous protein level in TNFα-stimulated HUVECs. Immunoprecipitation and in situ proximity ligation assays showed that coronin 1B depletion diminished the interaction between TNFα-induced TNF receptor-1-associated death domain protein (TRADD) and FADD, suggesting that coronin 1B is required for the TNFα-induced TRADD and FADD interaction and subsequent caspase-8/caspase-3 cascade activation, ultimately leading to apoptosis.