Mitochondrial dysfunction is an underlying cause of cardiomyocyte death and therefore plays a critical role in the development of many cardiac pathologies. This mitochondrial dysfunction is often mediated by the opening of the mitochondrial permeability transition (MPT) pore, which causes a rapid increase in inner mitochondrial membrane permeability. This in turn leads to ATP depletion, reactive oxygen species production, mitochondrial swelling and rupture. Consequently, our long-range goal is to identify the proteins that make up the MPT pore and understand the molecular mechanisms by which this complex is regulated. The MPT pore was originally proposed to consist of the voltage-dependent anion channel (VDAC) in the outer membrane, the adenine nucleotide translocase (ANT) in the inner membrane, plus a regulatory protein cyclophilin-D (CypD) in the matrix. However, genetic studies have revealed that VDAC and ANT are dispensable for MPT. Thus CypD still remains as the only bona fide member of the MPT pore complex. Importantly, the key factors that directly regulate CypD and its pro-MPT function remain to be elucidated. In particular, CypD-binding proteins that act to inhibit CypD's function have yet to be identified and the additional role that CypD phosphorylation plays in regulating MPT and cell death has not been comprehensively addressed. We have identified the mitochondrial matrix protein C1qbp as a novel CypD-binding protein and our strong preliminary data indicate that it can inhibit MPT and cell death. Conversely, we have found that the pro-death kinase GSK3 can sensitize cells to MPT and death, and that these effects are associated with CypD phosphorylation. Consequently, our central hypothesis is that C1qbp inhibits, whereas GSK3 promotes, MPT and cell death through the direct regulation of CypD. The objective of the present application is to utilize genetic, biochemical, physiological, and pharmacological techniques to systematically evaluate the roles of a CypD inhibitor (C1qbp) and a CypD activator (GSK3) in MPT, cardiac cell death, and the progression of myocardial disease.
In Aim 1 we will determine the functional involvement of C1qbp in the MPT response and cardiac myocyte death.
In Aim 2 we will evaluate the effects of GSK3-dependent CypD phosphorylation on MPT and cardiac cell death. The rationale for the proposed research is that once key mitochondrial proteins that regulate MPT and mitochondrial function are identified, they can be targeted as a means of treating a whole array of human cardiac diseases.

Public Health Relevance

The death of heart cells is an underlying cause of human heart disease, and is often mediated by a process called mitochondrial permeability transition. The proposed research is aimed at uncovering the molecular mechanisms that regulate mitochondrial permeability transition and therefore heart cell death. Once the key proteins that regulate this process are identified, they can then be targeted as a means of treating patients with heart disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL094404-06
Application #
8627698
Study Section
Myocardial Ischemia and Metabolism Study Section (MIM)
Program Officer
Schwartz, Lisa
Project Start
2008-12-16
Project End
2018-11-30
Budget Start
2013-12-23
Budget End
2014-11-30
Support Year
6
Fiscal Year
2014
Total Cost
$335,745
Indirect Cost
$110,745
Name
University of Missouri-Columbia
Department
Veterinary Sciences
Type
Schools of Veterinary Medicine
DUNS #
153890272
City
Columbia
State
MO
Country
United States
Zip Code
65211
Gutiérrez-Aguilar, Manuel; Baines, Christopher P (2015) Structural mechanisms of cyclophilin D-dependent control of the mitochondrial permeability transition pore. Biochim Biophys Acta 1850:2041-7
Gutiérrez-Aguilar, Manuel; Douglas, Diana L; Gibson, Anne K et al. (2014) Genetic manipulation of the cardiac mitochondrial phosphate carrier does not affect permeability transition. J Mol Cell Cardiol 72:316-25
Douglas, Diana L; Baines, Christopher P (2014) PARP1-mediated necrosis is dependent on parallel JNK and Ca²?/calpain pathways. J Cell Sci 127:4134-45
Marshall, Kurt D; Edwards, Michelle A; Krenz, Maike et al. (2014) Proteomic mapping of proteins released during necrosis and apoptosis from cultured neonatal cardiac myocytes. Am J Physiol Cell Physiol 306:C639-47
Marshall, Kurt D; Baines, Christopher P (2014) Necroptosis: is there a role for mitochondria? Front Physiol 5:323
McCommis, Kyle S; Douglas, Diana L; Krenz, Maike et al. (2013) Cardiac-specific hexokinase 2 overexpression attenuates hypertrophy by increasing pentose phosphate pathway flux. J Am Heart Assoc 2:e000355
Gutierrez-Aguilar, Manuel; Baines, Christopher P (2013) Physiological and pathological roles of mitochondrial SLC25 carriers. Biochem J 454:371-86
McGee, Allison M; Baines, Christopher P (2012) Phosphate is not an absolute requirement for the inhibitory effects of cyclosporin A or cyclophilin D deletion on mitochondrial permeability transition. Biochem J 443:185-91
McGee, Allison M; Baines, Christopher P (2011) Complement 1q-binding protein inhibits the mitochondrial permeability transition pore and protects against oxidative stress-induced death. Biochem J 433:119-25
Baines, Christopher P (2011) How and when do myocytes die during ischemia and reperfusion: the late phase. J Cardiovasc Pharmacol Ther 16:239-43

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