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.

Differential phosphorylation of mitogen-activated protein kinase families by epidermal growth factor and ultraviolet B irradiation in SV40-transformed human keratinocytes

“…Our study demonstrated that UVB irradiation-induced apoptosis of SVHK cells is accompanied by a delayed phosphorylation of p38 and JNK with similar time courses. The results are in line with the previous reports showing that UV mediated apoptosis is associated with the activation of JNK in immortalized mouse keratinocyte cell line, C50 [33] and in HaCaT cells [17].…”

“…The In many cells including keratinocytes, UVB irradiation-induced apoptosis depends on p38 [9,17,31]. Still UVB-induced activation of ERK and JNK has been reported in normal human keratinocytes and in HaCaT cells [24].…”

“…MAP kinases phosphorylate and regulate the activity of various enzymes and transcription factors including the EGF receptor, Rsk 90, -5 -phospholipase A2, Elk-1, c-Myc, ATF2, and c-Jun. In keratinocytes, recent studies have shown that p38 activation is essential for UVB irradiation-induced apoptosis [17] and that the inhibition of ERK phosphorylation augments the UVB-induced apoptosis [9].…”

Cellular response to oxidative stress: Signaling for suicide and survival*

“…Such an approach has yielded evidence for both pro-apoptotic (Bulavin et al, 1999;Shimizu et al, 1999;Zhuang et al, 2000;Gratton et al, 2001) as well as anti-apoptotic (Nemoto et al, 1998;Ivanov and Ronai, 2000) functions of these kinases. In addition, although many studies have correlated p38 activation with oxidative stress-induced apoptosis, in some of these circumstances, inhibiting the kinase through use of pharmacologic inhibitors does not alter the apoptosis (Wang et al, , 2000a.…”

p38 protects human melanoma cells from UV-induced apoptosis through down-regulation of NF-κB activity and Fas expression

“…For example, p38 elicits a pro-apoptotic signal in response to UV-B irradiation of human keratinocytes through upregulation of caspases (Shimizu et al, 1999). This signal can be attenuated by the PI3K/AKT pathway (Berra et al, 1998).…”