title: PKA-induced F-actin rearrangement requires phosphorylation of Hsp27 by the MAPKAP kinase MK5.
abstract: Mitogen-activated protein kinase (MAPK) pathways can play a role in F-actin dynamics. In particular, the p38 MAPK/MAPK-activated protein kinase 2 (MK2)/heat shock protein 27 (Hsp27) pathway is involved in F-actin alternations. Previously, we showed that MK5 is implicated in F-actin rearrangement induced by the cAMP/cAMP-dependent protein kinase pathway in PC12 cells, while others found Hsp27 to be a good in vitro MK5 substrate. Here we demonstrate that MK5 can specifically interact with Hsp27 in vivo and can induce phosphorylation at serine residues 78 and 82 in cells. siRNA-mediated depletion of Hsp27 protein levels, as well as overexpression of the non-phosphorylatable Hsp27-3A mutant prevented forskolin-induced F-actin reorganization. While ectopic expression of a constitutive active MK5 mutant was sufficient to induce F-actin rearrangement in PC12 cells, co-expression of Hsp27-3A could ablate this process. Our results imply that MK5 is involved in Hsp27-controlled F-actin dynamics in response to activation of the cAMP-dependent protein kinase pathway. These findings render the MK5/Hsp27 connection into a putative therapeutic target for conditions with aberrant Hsp27 phosphorylation such as metastasis, cardiovascular diseases, muscle atrophy, autoimmune skin disease and neuropathology.
authors.affiliation: University of Tromsø, Faculty of Medicine, Department of Microbiology and Virology, N-9037 Tromsø, Norway.
authors.forename: Sergiy
authors.initials: S
authors.lastname: Kostenko
authors.forename: Mona
authors.initials: M
authors.lastname: Johannessen
authors.forename: Ugo
authors.initials: U
authors.lastname: Moens
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D048370:MAP Kinase Kinase 2 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D016716:PC12 Cells; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats
chemical_list: D000199:Actins; D055551:HSP27 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D034741:RNA, Small Interfering; D005576:Colforsin; C111049:MAP-kinase-activated kinase 5; D000242:Cyclic AMP; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D048370:MAP Kinase Kinase 2