Type 2 diabetes mellitus incidence has increased dramatically. Among the life threatening complications is heart failure, which is preceded by bioenergetic dysfunction. Using mouse (db/db) and human (patient) type 2 diabetic models, we observed pronounced mitochondrial dysfunction culminating in a decreased ability to generate ATP for cardiac contraction. MicroRNAs (miRs) are non-coding RNAs that regulate translation. Using cross-linking immunoprecipitation and deep sequencing, we made the exciting observation, in both db/db and type 2 diabetic patients that miRs translocate into and out of cardiac mitochondria. Of particular interest was an increased miR- 378 presence in a functional regulatory context with mitochondrial genome-encoded ATP6 mRNA which codes for a subunit of the F0 proton motor that is part of the ATP synthase complex. Decreased ATP synthase functionality promotes bioenergetic deficit in the heart, promoting heart failure. Nevertheless, it is currently unclear whether miR-378 blockade can reduce mitochondrial dysfunction associated with the type 2 diabetic heart by direct interaction with the mitochondrial transcriptome. Further, the mechanisms responsible for the dynamic flux of miRs into the mitochondrion are undefined. One potential mechanism involves the participation of the mitochondrial RNA import protein polynucleotide phosphorylase (PNPase) which we have observed to be increased in mitochondria from db/db mice and type 2 diabetic patients. The studies being proposed address these gaps in knowledge and integrate in vitro cellular approaches with animal and human experimental models in an effort to begin to translate the findings to the type 2 diabetic patient. The objectives of this application are (1) determine the efficacy in vivo of miR-378 loss or its functional inhibition in a type 2 diabetic mouse model for restoring mitochondrial ATP6 protein expression and ATP generating capacity in the heart; (2) evaluate the therapeutic efficacy of a miR-378 inhibitor delivered to isolated human cardiomyocytes from type 2 diabetic patients; and (3) assess the contribution of PNPase to the mechanisms driving miR-378 flux into the mitochondrion. The central hypothesis of this application is that inhibition of miR-378 will disrupt its ability to translationally down-regulate ATP6 in the mitochondrion, preserving ATP generating capacity and limiting cardiac contractile dysfunction in the type 2 diabetic heart. Further, miR-378 flux into the mitochondrion can be modulated by manipulating PNPase levels and its structure. To test this hypothesis, an innovative approach has been proposed which employs novel experimental methodologies that are tested in cellular, animal and human models. The combination of work proposed is significant because it will provide insight into the mechanisms regulating miR distribution in the mitochondrion while providing initial translational insight into the therapeutic potential of miR-378 inhibition as a treatment strategy. Our approach merges mechanistic examination of a previously unexplored regulatory pathway contributing to mitochondrial dysfunction in the type 2 diabetic heart with preclinical evaluation of key molecular constituents participating in the axis.

Public Health Relevance

Type 2 diabetes mellitus incidence has increased dramatically. The prognosis for many of these subjects is poor, impacting healthcare costs, substantially. The proposed experiments are relevant to public health because they will enhance our understanding of the pathogenesis of diabetes-induced heart failure and provide information regarding targets for preventive and therapeutic interventions that will aid in the treatment of diabetes mellitus in the type 2 diabetic patient. Thus, the proposed research is relevant to the NIH?s mission that pertains to the pursuit of fundamental knowledge to extend healthy life and reduce the burden of illness.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Myocardial Ischemia and Metabolism Study Section (MIM)
Program Officer
Wong, Renee P
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
West Virginia University
Schools of Medicine
United States
Zip Code
Nichols, Cody E; Shepherd, Danielle L; Hathaway, Quincy A et al. (2018) Reactive oxygen species damage drives cardiac and mitochondrial dysfunction following acute nano-titanium dioxide inhalation exposure. Nanotoxicology 12:32-48
Hathaway, Quincy A; Pinti, Mark V; Durr, Andrya J et al. (2018) Regulating microRNA expression: at the heart of diabetes mellitus and the mitochondrion. Am J Physiol Heart Circ Physiol 314:H293-H310
Chen, Qun; Younus, Masood; Thompson, Jeremy et al. (2018) Intermediary metabolism and fatty acid oxidation: novel targets of electron transport chain-driven injury during ischemia and reperfusion. Am J Physiol Heart Circ Physiol 314:H787-H795
Shepherd, Danielle L; Hathaway, Quincy A; Nichols, Cody E et al. (2018) Mitochondrial proteome disruption in the diabetic heart through targeted epigenetic regulation at the mitochondrial heat shock protein 70 (mtHsp70) nuclear locus. J Mol Cell Cardiol 119:104-115
Stapleton, P A; Hathaway, Q A; Nichols, C E et al. (2018) Maternal engineered nanomaterial inhalation during gestation alters the fetal transcriptome. Part Fibre Toxicol 15:3
Baradan, Rohini; Hollander, John M; Das, Samarjit (2017) Mitochondrial miRNAs in diabetes: just the tip of the iceberg. Can J Physiol Pharmacol 95:1156-1162
Shepherd, Danielle L; Hathaway, Quincy A; Pinti, Mark V et al. (2017) Exploring the mitochondrial microRNA import pathway through Polynucleotide Phosphorylase (PNPase). J Mol Cell Cardiol 110:15-25
Corbin, Deborah R; Rehg, Jerold E; Shepherd, Danielle L et al. (2017) Excess coenzyme A reduces skeletal muscle performance and strength in mice overexpressing human PANK2. Mol Genet Metab 120:350-362
Hathaway, Quincy A; Nichols, Cody E; Shepherd, Danielle L et al. (2017) Maternal-engineered nanomaterial exposure disrupts progeny cardiac function and bioenergetics. Am J Physiol Heart Circ Physiol 312:H446-H458
Pinti, Mark V; Hathaway, Quincy A; Hollander, John M (2017) Role of microRNA in metabolic shift during heart failure. Am J Physiol Heart Circ Physiol 312:H33-H45

Showing the most recent 10 out of 11 publications