Pim-1 regulates cardiomyocyte survival downstream of Akt |
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Authors: | Muraski John A Rota Marcello Misao Yu Fransioli Jenna Cottage Christopher Gude Natalie Esposito Grazia Delucchi Francesca Arcarese Michael Alvarez Roberto Siddiqi Sailay Emmanuel Gregory N Wu Weitao Fischer Kimberlee Martindale Joshua J Glembotski Christopher C Leri Annarosa Kajstura Jan Magnuson Nancy Berns Anton Beretta Remus M Houser Steven R Schaefer Erik M Anversa Piero Sussman Mark A |
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Affiliation: | San Diego State University Heart Institute, San Diego State University, 5500 Campanile Drive, San Diego, California 92182, USA. |
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Abstract: | The serine-threonine kinases Pim-1 and Akt regulate cellular proliferation and survival. Although Akt is known to be a crucial signaling protein in the myocardium, the role of Pim-1 has been overlooked. Pim-1 expression in the myocardium of mice decreased during postnatal development, re-emerged after acute pathological injury in mice and was increased in failing hearts of both mice and humans. Cardioprotective stimuli associated with Akt activation induced Pim-1 expression, but compensatory increases in Akt abundance and phosphorylation after pathological injury by infarction or pressure overload did not protect the myocardium in Pim-1-deficient mice. Transgenic expression of Pim-1 in the myocardium protected mice from infarction injury, and Pim-1 expression inhibited cardiomyocyte apoptosis with concomitant increases in Bcl-2 and Bcl-X(L) protein levels, as well as in Bad phosphorylation levels. Relative to nontransgenic controls, calcium dynamics were significantly enhanced in Pim-1-overexpressing transgenic hearts, associated with increased expression of SERCA2a, and were depressed in Pim-1-deficient hearts. Collectively, these data suggest that Pim-1 is a crucial facet of cardioprotection downstream of Akt. |
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