Protein kinase C alpha and zeta differentially regulate death-inducing signaling complex formation in cigarette smoke extract-induced apoptosis.
Cigarette smoke, a major risk factor in emphysema, causes cell death by incompletely understood mechanisms. Death-inducing signaling complex (DISC) formation is an initial event in Fas-mediated apoptosis. We demonstrate that cigarette smoke extract (CSE) induces DISC formation in human lung fibroblasts (MRC-5) and promotes DISC trafficking from the Golgi complex to membrane lipid rafts. We demonstrate a novel role of protein kinase C (PKC) in the regulation of DISC formation and trafficking. The PKC isoforms, PKCalpha, zeta, epsilon, and eta, were activated by CSE exposure. Overexpression of wild-type PKCalpha inhibited, while PKCzeta promoted, CSE-induced cell death. Dominant-negative (dn)PKCzeta protected against CSE-induced cell death by suppressing DISC formation and caspase-3 activation, while dnPKCalpha enhanced cell death by promoting these events. DISC formation was augmented by wortmannin, an inhibitor of PI3K. CSE-induced Akt phosphorylation was reduced by dnPKCalpha, but it was increased by dnPKCzeta. Expression of PKCalpha in vivo inhibited DISC formation, caspase-3/8 activation, lung injury, and cell death after prolonged cigarette smoke exposure, whereas expression of PKCzeta promoted caspase-3 activation. In conclusion, CSE-induced DISC formation is differentially regulated by PKCalpha and PKCzeta via the PI3K/Akt pathway. These results suggest that modulation of PKC may have therapeutic potential in the prevention of smoke-related lung injury.
Park
Jeong-Woong
JW
Department of Pulmonary and Critical Care Medicine, Gachon Medical School, Gil Medical Center, Inchon, Republic of Korea.
Kim
Hong Pyo
HP
Lee
Seon-Jin
SJ
Wang
Xue
X
Wang
Yong
Y
Ifedigbo
Emeka
E
Watkins
Simon C
SC
Ohba
Motoi
M
Ryter
Stefan W
SW
Vyas
Yatin M
YM
Choi
Augustine M K
AM
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010768:Phosphoserine / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D051571:Protein Kinase C-alpha / Q000378:metabolism*; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D014026:Nicotiana / Q000737:chemistry*; D014028:Tobacco Smoke Pollution; D000099221:Protein Kinase C zeta
D020169:Caspases; D053418:Death Domain Receptor Signaling Adaptor Proteins; D010768:Phosphoserine; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051057:Proto-Oncogene Proteins c-akt; D014028:Tobacco Smoke Pollution; D000099221:Protein Kinase C zeta