Translocation of Protein Kinase Cε and Protein Kinase Cδ to Membrane Is Required for Ultraviolet B-induced Activation of Mitogen-activated Protein Kinases and Apoptosis

Abstract

UV-induced signal transduction may be involved in tumor promotion and induction of apoptosis. The role of protein kinase C (PKC) in UVB-induced signal transduction is not well understood. This study showed that UVB markedly induced translocation of membrane-associated PKC⑀ and PKC␦, but not PKC␣, from cytosol to membrane. Dominant negative mutant (DNM) PKC⑀ or PKC␦ inhibited UVB-induced translocation of PKC⑀ and PKC␦, respectively. UVB-induced activation of extracellular signal-regulated protein kinases (Erks) and c-Jun NH 2 -terminal kinases (JNKs) was strongly inhibited by DNM PKC⑀ and PKC␦, whereas the DNM of PKC␣ was less effective on the UVB-induced phosphorylation of Erks and JNKs. Among the PKC inhibitors used only rottlerin, a selective inhibitor of PKC␦, markedly inhibited the UVB-induced activation of Erks and JNKs, but not p38 kinases. Safingol, a selective inhibitor for PKC␣, did not show any inhibitory effect on UVB-induced mitogen-activated protein kinase activation. GF109203X is a stronger inhibitor of classical PKC than novel PKC. Lower concentrations of GF109203X (<10 M) had no effect on UVB-induced activation of Erks or JNKs. However, at higher concentrations (over 20 M), GF109203X inhibited UVB-induced activation of JNKs, Erks, and even p38 kinases. Meanwhile, rottlerin and GF109203X markedly inhibited UVB-induced apoptosis of JB6 cells, whereas safingol had little inhibitory effect. DNM-Erk2 cells and PD98059, a selective inhibitor for mitogen-activated protein kinase/extracellular signal-regulated kinase 1 that directly activates Erks, inhibited UVBinduced apoptosis. DNM-JNK1 cells also blocked UVBinduced apoptosis, whereas SB202190, a specific inhibitor for p38 kinases, did not produce the inhibitory effect. These data demonstrate that PKC␦ and PKC⑀, but not PKC␣, mediate UVB-induced signal transduction and apoptosis in JB6 cells through activation of Erks and JNKs.UV radiation from the sun is the major environmental factor responsible for a high incidence of nonmelanoma skin cancer (1-4). The electromagnetic spectrum of UV can be divided into three parts: UVA (320 -400 nm), UVB (290 -320 nm), and UVC (100 -290 nm) (2). In animal experiments, both UVB and UVC can act as complete carcinogens, whereas UVA can only act as a tumor promoter (2-6). Because UVC light does not penetrate the atmosphere (2), UVB radiation is believed to be responsible for most of the carcinogenic effects of sun exposure (2, 7-9). Irradiation by UVB or UVC is known to damage DNA and could cause gene mutations such as p53 or ras mutations (10 -12). Because of the importance of these genes in growth and differentiation, a DNA-damaging effect has been proposed as the mechanism of UV-induced initiation (2-9). The mechanism behind the tumor-promoting ability of UV, however, is not well understood.A number of reports have established that UVC and UVB induce certain gene expression (13-16). These "UV responses" activate several signal transduction pathways and transcription factors (14, 17). There are two transcription facto...

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

“…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].…”

Activation of p38 MAP kinase and ERK are required for ultraviolet-B induced c-fos gene expression in human keratinocytes

“…Exposure of cells to C2-ceramide induced dose dependent activation of JNK . In addition, UVB-induced activation of ERK and JNK was strongly inhibited by dominant negative mutant of PKCe and PKCd (Chen et al, 1999a). Recently, a line of evidence showed that inhibition of ERK activation blocked UVB induced AP-1 activation in mouse epidermal cells, and over expression of ERK restored UV responsiveness, indicating that ERK was necessary for UVB induced AP-1 activation (Huang et al, 1999).…”

Protein Kinase C Delta Cleavage Initiates an Aberrant Signal Transduction Pathway after Cardiac Arrest and Oxygen Glucose Deprivation

“…This contention is supported by findings that dPKC plays a central role in the regulation of cell apoptosis in response to a large and diverse array of apoptotic stimuli (Brodie and Blumberg, 2003). For example, during the initiation of apoptosis, dPKC has been shown to translocate from cytosol to a variety of cellular organelles including mitochondria (Mochly-Rosen, 1995;Sawai et al, 1997;Chen et al, 1999;Dal Pra et al, 1999;Li et al, 1999;Dempsey et al, 2000;Majumder et al, 2000). Also, we recently demonstrated in an in vitro study that increased dPKC translocation correlated with neuronal death in CA1 region of hippocampus, implying a definite role of dPKC in neuronal death (Bright et al, 2003(Bright et al, , 2004.…”