title: Elimination of protein kinase MK5/PRAK activity by targeted homologous recombination.
abstract: MK5 (mitogen-activated protein kinase [MAPK]-activated protein kinase 5), also designated PRAK (p38-regulated and -activated kinase), was deleted from mice by homologous recombination. Although no MK5 full-length protein and kinase activity was detected in the MK5 knockout mice, the animals were viable and fertile and did not display abnormalities in tissue morphology or behavior. In addition, these mice did not show increased resistance to endotoxic shock or decreased lipopolysaccharide-induced cytokine production. Hence, MK5 deletion resulted in a phenotype very different from the complex inflammation-impaired phenotype of mice deficient in MK2, although MK2 and MK5 exhibit evolutional, structural, and apparent extensive functional similarities. To explain this discrepancy, we used wild-type cells and embryonic fibroblasts from both MK2 and MK5 knockout mice as controls to reexamine the mechanism of activation, the interaction with endogenous p38 MAPK, and the substrate specificity of both enzymes. In contrast to MK2, which shows interaction with and chaperoning properties for p38 MAPK and which is activated by extracellular stresses such as arsenite or sorbitol treatment, endogenous MK5 did not show these properties. Furthermore, endogenous MK5 is not able to phosphorylate Hsp27 in vitro and in vivo. We conclude that the differences between the phenotypes of MK5- and MK2-deficient mice result from clearly different functional properties of both enzymes.
authors.affiliation: Institute of Biochemistry, Medical School Hannover, 30625 Hannover, Germany.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shi
authors.forename: Alexey
authors.initials: A
authors.lastname: Kotlyarov
authors.forename: Kathrin
authors.initials: K
authors.lastname: Laabeta
authors.forename: Achim D
authors.initials: AD
authors.lastname: Gruber
authors.forename: Elke
authors.initials: E
authors.lastname: Butt
authors.forename: Katrin
authors.initials: K
authors.lastname: Marcus
authors.forename: Helmut E
authors.initials: HE
authors.lastname: Meyer
authors.forename: Anke
authors.initials: A
authors.lastname: Friedrich
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Volk
authors.forename: Matthias
authors.initials: M
authors.lastname: Gaestel
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D009363:Neoplasm Proteins / Q000378:metabolism; D010179:Pancreas / Q000166:cytology / Q000378:metabolism; D010641:Phenotype; D011485:Protein Binding; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D016207:Cytokines; D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; D020928:Mitogen-Activated Protein Kinases; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C486113:Hsbp1 protein, mouse; C111049:MAP-kinase-activated kinase 5