期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2013
卷号：110
期号：5
页码：E387-E396
DOI：10.1073/pnas.1221670110
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceEarly signaling events leading to protection in the heart under cardiac injury are poorly understood. We identified one such protein, A kinase interacting protein (AKIP1), as a modulator that responds to oxidative stress; up-regulation of AKIP1 showed protection to ischemic injury through enhanced mitochondrial integrity. We show AKIP1 functions as a molecular scaffold via interaction with mitochondrial apoptosis inducing factor and increases protein kinase A activity. These mitochondrial signaling complexes assembled by AKIP1 alter the physiological response of the heart under ischemic stress. Understanding molecular activity and regulation of AKIP1 could lead to novel therapeutic approaches to limit myocardial injury. cAMP-dependent protein kinase (PKA) regulates a myriad of functions in the heart, including cardiac contractility, myocardial metabolism, and gene expression. However, a molecular integrator of the PKA response in the heart is unknown. Here, we show that the PKA adaptor A-kinase interacting protein 1 (AKIP1) is up-regulated in cardiac myocytes in response to oxidant stress. Mice with cardiac gene transfer of AKIP1 have enhanced protection to ischemic stress. We hypothesized that this adaptation to stress was mitochondrial-dependent. AKIP1 interacted with the mitochondrial localized apoptosis inducing factor (AIF) under both normal and oxidant stress. When cardiac myocytes or whole hearts are exposed to oxidant and ischemic stress, levels of both AKIP1 and AIF were enhanced. AKIP1 is preferentially localized to interfibrillary mitochondria and up-regulated in this cardiac mitochondrial subpopulation on ischemic injury. Mitochondria isolated from AKIP1 gene-transferred hearts showed increased mitochondrial localization of AKIP1, decreased reactive oxygen species generation, enhanced calcium tolerance, decreased mitochondrial cytochrome C release, and enhance phosphorylation of mitochondrial PKA substrates on ischemic stress. These observations highlight AKIP1 as a critical molecular regulator and a therapeutic control point for stress adaptation in the heart.
