MK2 nonenzymatically promotes nuclear translocation of caspase-3 and resultant apoptosis

The study investigated the role of mitogen-activated protein kinase-activated protein kinase 2 (MK2) in promoting nuclear translocation of caspase-3 during apoptosis. The researchers overexpressed various constructs of MK2 in two non-small cell lung cancer cell lines with low MK2 expression and evaluated cell death and protein analyses. They found that MK2 directly phosphorylates caspase-3, but its enzymatic function was dispensable for caspase-3 nuclear translocation and apoptosis. Instead, a nonenzymatic function of MK2 in chaperoning nuclear trafficking was required. The study suggests that MK2 may act as a molecular switch in regulating the cytosolic and nuclear functions of caspase-3.