Proteins secreted by the heart are called cardiokines. After secretion, cardiokines, such as cytokines, growth promoters and stem cell homing factors affect ischemic damage, as well as stem cell survival and engraftment. But ischemia impairs protein folding and secretion, and negatively impacts stem cell-mediated regeneration. However, we discovered a secretion process that resists this inhibition, enabling the release of certain beneficial cardiokines, just when they are needed the most. The objectives of this study are to examine the functions of, and molecular mechanisms governing this secretion process in cardiac myocytes, in vitro and in vivo, and in cardiac stem cells. We discovered this process while studying the beneficial cardiokine, mesencephalic astrocyte-derived neurotrophic factor (MANF), which resides in the endoplasmic/sarcomplasmic reticulum (ER/SR). Our hypothesis is that 1) GRP78 regulates the secretion of beneficial ER stress cardiokines from cardiac myocytes and cardiac progenitor cells by mediating the conditional retention of proteins in the ER/SR, and 2) CPCs are specially configured with a novel cytosolic form of GRP78 that enhances survival, as well as cardiokine secretion during ER stress.We will address this hypothesis by using MANF as a model cardiokine, GRP78 gain- and loss-of-function, cultured cells and mouse hearts, / AV9-mediated in vivo gene transfer, and zero-distance live cell cross linking in the following specific aims: 1- to determine the mechanism by which GRP78 regulates cardiokine secretion from cardiac myocytes, 2- to assess GRP78-regulated cardiokine secretion in the heart, in vivo, and determine the effects of disrupting this secretion on ischemic damage and regeneration, and 3- to examine the effects of GRP78 in the ER, as well as a novel, cytosolic form of GRP78 on cardiokine secretion, responses to ER stress and survival of cardiac stem cells. The results of these studies will facilitate the design of therapeutic strategies aimed at enhancing the secretion of beneficial cardiokines that minimize damage and maximize regeneration.

Public Health Relevance

Due to the irretrievable loss of functional myocardium, ischemic heart disease is a leading cause of morbidity and mortality. Since paracrine function is critical for myocyte and stem cell survival during ischemia, a better understanding of secretion in the ischemic heart, which will result from the proposed studies, is required to develop new approaches for reducing tissue loss and improving stem cell-mediated myocardial regeneration.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
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Heart, Lung, and Blood Initial Review Group (HLBP)
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San Diego State University
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Parker, Sarah J; Stotland, Aleksandr; MacFarlane, Elena et al. (2018) Proteomics reveals Rictor as a noncanonical TGF-? signaling target during aneurysm progression in Marfan mice. Am J Physiol Heart Circ Physiol 315:H1112-H1126
Broughton, Kathleen M; Wang, Bingyan J; Firouzi, Fareheh et al. (2018) Mechanisms of Cardiac Repair and Regeneration. Circ Res 122:1151-1163
Broughton, Kathleen M; Sussman, Mark A (2018) Enhancement Strategies for Cardiac Regenerative Cell Therapy: Focus on Adult Stem Cells. Circ Res 123:177-187
Gude, Natalie A; Sussman, Mark A (2018) Chasing c-Kit through the heart: Taking a broader view. Pharmacol Res 127:110-115
Yu, Olivia M; Benitez, Jorge A; Plouffe, Steven W et al. (2018) YAP and MRTF-A, transcriptional co-activators of RhoA-mediated gene expression, are critical for glioblastoma tumorigenicity. Oncogene 37:5492-5507
Gude, Natalie A; Firouzi, Fareheh; Broughton, Kathleen M et al. (2018) Cardiac c-Kit Biology Revealed by Inducible Transgenesis. Circ Res 123:57-72
Shires, Sarah E; Gustafsson, Åsa B (2018) Regulating Renewable Energy: Connecting AMPK?2 to PINK1/Parkin-Mediated Mitophagy in the Heart. Circ Res 122:649-651
Woodall, Benjamin P; Gustafsson, Åsa B (2018) Mesenchymal Stem Cell-Mediated Autophagy Inhibition. Circ Res 123:518-520
Lampert, Mark A; Gustafsson, Åsa B (2018) Balancing Autophagy for a Healthy Heart. Curr Opin Physiol 1:21-26
Kubli, Dieter A; Sussman, Mark A (2018) Editorial commentary: Mitochondrial autophagy in cardiac aging is all fluxed up. Trends Cardiovasc Med 28:261-262

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