We investigated the activation of three subfamilies of mitogen-activated protein kinases (MAPKs), namely the stress-activated protein kinases/c-Jun N-terminal kinases (SAPKs/JNKs), the extracellularly responsive kinases (ERKs) and p38-MAPK, by oxidative stress as exemplified by H2O2 in primary cultures of neonatal rat ventricular myocytes. The 46 and 54 kDa species of SAPKs/JNKs were activated 5- and 10-fold, respectively, by 0.1 mM H2O2 (the maximally effective concentration). Maximal activation occurred at 15–30 min, but was still detectable after 2 h. Both ERK1 and ERK2 were activated 16-fold by 0.1 mM H2O2 with a similar time course to the SAPKs/JNKs, and this was comparable with their activation by 1 µM PMA, the most powerful activator of ERKs that we have so far identified in these cells. The activation of ERKs by H2O2 was inhibited by PD98059, which inhibits the activation of MAPK (or ERK) kinases, and by the protein kinase C (PKC) inhibitor, GF109203X. ERK activation was also inhibited by down-regulation of PMA-sensitive PKC isoforms. p38-MAPK was activated by 0.1 mM H2O2 as shown by an increase in its phosphorylation. However, maximal phosphorylation (activation) was more rapid (< 5 min) than for the SAPKs/JNKs or the ERKs. We studied the downstream consequences of p38-MAPK activation by examining activation of MAPK-activated protein kinase 2 (MAPKAPK2) and phosphorylation of the MAPKAPK2 substrate, the small heat shock protein HSP25/27. As with p38-MAPK, MAPKAPK2 was rapidly activated (maximal within 5 min) by 0.1 mM H2O2. This activation was abolished by 10 µM SB203580, a selective inhibitor of certain p38-MAPK isoforms. The phosphorylation of HSP25/27 rapidly followed activation of MAPKAPK2 and was also inhibited by SB203580. Phosphorylation of HSP25/27 was associated with a decrease in its aggregation state. These data indicate that oxidative stress is a powerful activator of all three MAPK subfamilies in neonatal rat ventricular myocytes. Activation of all three MAPKs has been associated with the development of the hypertrophic phenotype. However, stimulation of p38-MAPK and the consequent phosphorylation of HSP25/27 may also be important in cardioprotection.
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Research Article|
August 01 1998
Stimulation of multiple mitogen-activated protein kinase sub-families by oxidative stress and phosphorylation of the small heat shock protein, HSP25/27, in neonatal ventricular myocytes
Angela CLERK;
Angela CLERK
*NHLI Division (Cardiac Medicine), Royal Brompton Campus, Imperial College School of Medicine, Dovehouse Street, London SW3 6LY, U.K.
†Division of Biomedical Sciences, Charing Cross Campus, Imperial College School of Medicine, Fulham Palace Road, London W6 8RF, U.K.
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Ashour MICHAEL;
Ashour MICHAEL
*NHLI Division (Cardiac Medicine), Royal Brompton Campus, Imperial College School of Medicine, Dovehouse Street, London SW3 6LY, U.K.
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Peter H. SUGDEN
Peter H. SUGDEN
1
*NHLI Division (Cardiac Medicine), Royal Brompton Campus, Imperial College School of Medicine, Dovehouse Street, London SW3 6LY, U.K.
1To whom correspondence should be addressed (e-mail p.sugden@ic.ac.uk).
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Publisher: Portland Press Ltd
Received:
February 25 1998
Revision Received:
April 17 1998
Accepted:
May 11 1998
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1998
1998
Biochem J (1998) 333 (3): 581–589.
Article history
Received:
February 25 1998
Revision Received:
April 17 1998
Accepted:
May 11 1998
Citation
Angela CLERK, Ashour MICHAEL, Peter H. SUGDEN; Stimulation of multiple mitogen-activated protein kinase sub-families by oxidative stress and phosphorylation of the small heat shock protein, HSP25/27, in neonatal ventricular myocytes. Biochem J 1 August 1998; 333 (3): 581–589. doi: https://doi.org/10.1042/bj3330581
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