Submitted on December 13, 2005
Accepted on May 10, 2006
ALTERATIONS IN OXIDATIVE PHOSPHORYLATION COMPLEX PROTEINS IN THE HEARTS OF TRANSGENIC MICE THAT OVEREXPRESS THE p38 MAP KINASE ACTIVATOR, MAP KINASE KINASE 6
Jason A Wall1, Jing Wei2, Mimi Ly1, Peter Belmont1, Joshua J Mardinale1, Diem Tran2, Jun Sun2, Wenqiong J Chen2, Wen Yu2, Paul Oeller2, Steve Briggs3, Asa B Gustafsson4, M R Sayen5, Roberta A. Gottlieb5, and Christopher C Glembotski1*
1 Biology, San Diego State University, San Diego, California, United States
2 Diversa Corporation, San Diego, California, United States
3 Biology, University of CA at San Diego, San Diego, California, United States
4 Molecular and Experimental Medicine, The Scripps Research Institute, San Diego, California, United States
5 Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States
* To whom correspondence should be addressed. E-mail: cglembotski{at}sciences.sdsu.edu.
Ischemia reperfusion (I/R) has critical consequences in the heart. Recent studies on the functions of I/R-activated kinases, such as p38 mitogen activated protein kinase (MAPK) showed that I/R injury is reduced in the hearts of transgenic mice that over-express the p38 MAPK activator, MAPK kinase 6 (MKK6). This protection may be fostered by changes in the levels of many proteins not currently known to be regulated by p38. To examine this possibility we employed multidimensional protein identification technology (MudPIT) to characterize changes in levels of proteins in MKK6 transgenic mouse hearts, focusing on proteins in mitochondria, which play key roles in mediating I/R injury in the heart. Of the 386 mitochondrial proteins identified, the levels of 58 were decreased, while only 2 were increased in the MKK6 transgenic mouse hearts. Amongst those that were decreased were 21 mitochondrial oxidative phosphorylation (ox phos) complex proteins, which was unexpected, since p38 is not known to mediate such decreases. Immunoblotting verified that proteins in each of the 5 ox phos complexes were reduced in MKK6 mouse hearts. Upon assessing functional consequences of these reductions we found that MKK6 mouse heart mitochondria exhibited 50% lower oxidative respiration and I/R-mediated reactive oxygen species (ROS) generation, both of which are predicted consequences of decreased ox phos complex proteins. Thus, the cardioprotection observed in MKK6 transgenic mouse hearts may be partly due to decreased electron transport, which is potentially beneficial, since damaging ROS are known to be generated by mitochondrial complexes I and III during reoxygenation.
