Distinct roles of MK2 and MK5 in cAMP/PKA- and stress/p38MAPK-induced heat shock protein 27 phosphorylation.
Classical mammalian mitogen-activated protein kinase (MAPK) pathways consist of a cascade of three successive phosphorylation events resulting in the phosphorylation of a variety of substrates, including another class of protein kinases referred to as MAPK-activating protein kinases (MAPKAPKs). The MAPKAPKs MK2, MK3 and MK5 are closely related, but MK2 and MK3 are the major downstream targets of the p38MAPK pathway, while MK5 can be activated by the atypical MAPK ERK3 and ERK4, protein kinase A (PKA), and maybe p38MAPK. MK2, MK3, and MK5 can phosphorylate the common substrate small heat shock protein 27 (HSP27), a modification that regulates the role of HSP27 in actin polymerization. Both stress and cAMP elevating stimuli can cause F-actin remodeling, but whereas the in vivo role of p38MAPK-MK2 in stress-triggered HSP27 phosphorylation and actin reorganization is well established, it is not known whether MK2 is involved in cAMP/PKA-induced F-actin rearrangements. On the other hand, MK5 can phosphorylate HSP27 and cause cytoskeletal changes in a cAMP/PKA-dependent manner, but its role as HSP27 kinase in stress-induced F-actin remodeling is disputed. Therefore, we wanted to investigate the implication of MK2 and MK5 in stress- and PKA-induced HSP27 phosphorylation. Using HEK293 cells, we show that MK2, MK3, and MK5 are expressed in these cells, but MK3 protein levels are very moderate. Stress- and cAMP-elevating stimuli, as well as ectopic expression of active MKK6 plus p38MAPK or the catalytic subunit of PKA trigger HSP27 phosphorylation, and specific inhibitors of p38MAPK and PKA prevent this phosphorylation. Depletion of MK2, but not MK3 and MK5 diminished stress-induced HSP27 phosphorylation, while only knockdown of MK5 reduced PKA-induced phosphoHSP27 levels. Stimulation of the p38MAPK, but not the PKA pathway, caused activation of MK2. Our results suggest that in HEK293 cells MK2 is the HSP27 kinase engaged in stress-induced, but not cAMP-induced phosphorylation of HSP27, while MK5 seems to be the sole MK to mediate HSP27 phosphorylation in response to stimulation of the PKA pathway. Thus, despite the same substrate specificity towards HSP27, MK2 and MK5 are implicated in different signaling pathways causing actin reorganization.
CitationJournal of Molecular Signaling (2011), 6:4
The following license file are associated with this item:
Showing items related by title, author, creator and subject.
Prognostic Impacts of Angiopoietins in NSCLC Tumor Cells and Stroma : VEGF-A Impact Is Strongly Associated with Ang-2 Andersen, Sigve; Dønnem, Tom; Al-Shibli, Khalid Ibrahim; Al-Saad, Samer; Stenvold, Helge; Busund, Lill-Tove; Bremnes, Roy M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)Angiopoietins and their receptor Tie-2 are, in concert with VEGF-A, key mediators in angiogenesis. This study evaluates the prognostic impact of all known human angiopoietins (Ang-1, Ang-2 and Ang-4) and their receptor Tie-2, as well as their relation to the prognostic expression of VEGF-A. 335 unselected stage I-IIIA NSCLC-patients were included and tissue samples of respective tumor cells and ...
Humant papillomavirus : en litteraturstudie om HPV, dets relasjon til cancer og tiltak mot videre spredning av virus Gabrielsen, Endre (Master thesis; Mastergradsoppgave, 2012-06-01)I 1983 oppdaget zur Hausen sammenhengen mellom Humant Papillomavirus (HPV) og livmorhalskreft. På denne tiden visste man ikke at det var HPV som var årsaken til at Helaceller kunne leve in vitro. Ny forskning relaterer HPV til en rekke andre cancertyper. En stor andel anal-, oropharyngeal-, penis-, vaginal-, og vulvacancer skyldes HPV. Det er også påvist HPV i tumorvev fra øsofagus, larynx, lunge, ...
Hoem, Gry (Master thesis; Mastergradsoppgave, 2012-06)Fragile X syndrome (FXS) is caused by an expanded CGG repeat (>200 repeats) in the 5’ un-translated portion of the fragile mental retardation 1 gene (FMR1) leading to deficiency or absence of the FMR1 protein (FMRP). FMRP is an RNA carrier protein that controls the translation of a number of other genes that regulate synaptic development and plasticity. Autism occurs in approximately 30% of FXS ...