title: Protein kinase Cdelta regulates keratinocyte death and survival by regulating activity and subcellular localization of a p38delta-extracellular signal-regulated kinase 1/2 complex.
abstract: Protein kinase Cdelta (PKCdelta) is an important regulator of apoptosis in epidermal keratinocytes. However, little information is available regarding the downstream kinases that mediate PKCdelta-dependent keratinocyte death. This study implicates p38delta mitogen-activated protein kinase (MAPK) as a downstream carrier of the PKCdelta-dependent death signal. We show that coexpression of PKCdelta with p38delta produces profound apoptosis-like morphological changes. These morphological changes are associated with increased sub-G(1) cell population, cytochrome c release, loss of mitochondrial membrane potential, caspase activation, and PARP cleavage. This death response is specific for the combination of PKCdelta and p38delta and is not produced by replacing PKCdelta with PKCalpha or p38delta with p38alpha. A constitutively active form of MEK6, an upstream activator of p38delta, can also produce cell death when coupled with p38delta. In addition, concurrent p38delta activation and extracellular signal-regulated kinase 1/2 (ERK1/2) inactivation are required for apoptosis. Regarding this inverse regulation, we describe a p38delta-ERK1/2 complex that may coordinate these changes in activity. We further show that this p38delta-ERK1/2 complex relocates into the nucleus in response to PKCdelta expression. This regulation appears to be physiological, since H(2)O(2), a known inducer of keratinocyte apoptosis, promotes identical PKCdelta and p38delta-ERK1/2 activity changes, leading to similar morphological changes.
authors.affiliation: Department of Physiology, Case Western Reserve University School of Medicine, 2109 Adelbert Rd., Cleveland, OH 44106-4970, USA.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Efimova
authors.forename: Ann-Marie
authors.initials: AM
authors.lastname: Broome
authors.forename: Richard L
authors.initials: RL
authors.lastname: Eckert
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004789:Enzyme Activation; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015603:Keratinocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D048669:MAP Kinase Kinase 6; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048292:Mitogen-Activated Protein Kinase 13; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051745:Protein Kinase C-delta; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry
chemical_list: D011994:Recombinant Proteins; D014443:Tyrosine; D006861:Hydrogen Peroxide; D048292:Mitogen-Activated Protein Kinase 13; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048669:MAP Kinase Kinase 6; C482566:MAP2K6 protein, human