title: Activation of p38 mitogen-activated protein kinase and caspases in UVB-induced apoptosis of human keratinocyte HaCaT cells.
abstract: Exposure of human keratinocyte HaCaT cells to ultraviolet B-irradiation induced apoptotic morphologic changes. In this study, we found that the ultraviolet B irradiation (0.25 J per cm2) induced phosphorylation of p38 mitogen-activated protein kinase and c-jun N-terminal protein kinase, and also significant activation of caspase-3 (CPP32-like protease) and a small increase of caspase-1 (ICE-like protease) activity in the early stages of ultraviolet B-induced apoptosis. Pretreatments of the cells with a p38 mitogen-activated protein kinase inhibitor, SB203580, and a caspase-3 inhibitor, Ac-Asp-Met-Gln-Asp-1-aldehyde, suppressed the ultraviolet B irradiation-induced apoptosis by approximately 60% as estimated by nuclear staining and DNA laddering. Pretreatment with caspase-1 inhibitor, Ac-Tyr-Val-Lys-Asp-aldehyde was without effect. Ultraviolet B-induced caspase-3 activation resulted in cleavage of poly(ADP) ribose polymerase, which was abolished by the caspase-3 inhibitor. SB203580 pretreatment prevented activation of caspase-3 and caspase-1, and also suppressed the cleavage of poly(ADP) ribose polymerase. Neither ceramide generation nor sphingomyelinase activation (neutral and acid) was observed in the ultraviolet B-irradiated HaCaT cells. Also various antioxidants did not affect the caspase activation induced by ultraviolet B irradiation. These results indicated that activation of p38 mitogen-activated protein kinase upstream of caspases may play an important part in the apoptotic process of keratinocytes exposed to ultraviolet B irradiation.
authors.affiliation: Department of Dermatology, Gifu University School of Medicine, Tsukasamachi, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Shimizu
authors.forename: Y
authors.initials: Y
authors.lastname: Banno
authors.forename: N
authors.initials: N
authors.lastname: Sumi
authors.forename: T
authors.initials: T
authors.lastname: Naganawa
authors.forename: Y
authors.initials: Y
authors.lastname: Kitajima
authors.forename: Y
authors.initials: Y
authors.lastname: Nozawa
mesh_terms: D017209:Apoptosis; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000473:pathology; D002518:Ceramides / Q000378:metabolism; D053938:DNA Fragmentation; D004789:Enzyme Activation / Q000528:radiation effects; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D014466:Ultraviolet Rays; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D061945:Caspase Inhibitors; D002518:Ceramides; D007093:Imidazoles; D011725:Pyridines; D017382:Reactive Oxygen Species; D011065:Poly(ADP-ribose) Polymerases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020169:Caspases; C093642:SB 203580