Activation of a 36-kDa Myelin Basic Protein Kinase during Cadmium-Induced Apoptosis in Human Leukemia HL-60 Cells

Abstract

Cadmium (Cd) is a well-known modulator of intracellular signal transduction including mitogen-activated protein kinases and protein kinase C. In this study, we investigated activation of a kinase using myelin basic protein (MBP) as a substrate during Cd-induced apoptosis in human leukemia HL-60 cells. To detect a kinase during Cd-induced apoptosis in HL-60 cells, we performed an in-gel kinase assay using MBP as a substrate and found that Cd induced the activation of a kinase with an apparent molecular mass of 36 kDa. The time-course of appearance of DNA ladders induced by Cd was consistent with that of activation of this kinase. The kinetics of activation of p36 MBP kinase was different from that of p38 mitogen-activated protein kinase (p38MAPK). Activation of p36 MBP kinase was also observed with kinetics distinct from that of activation of p38MAPK during mercuric chloride-induced apoptosis. This is the first report on activation of p36 MBP kinase during Cd- or Hg-induced apoptosis.