Proceedings of The Physiological Society

Mitochondria: Form and function (London, UK) (2017) Proc Physiol Soc 38, C09

Oral Communications

Preventing Glyoxalase-1 (Glo-I) downregulation attenuates mitochondria dysfunction in hearts of diabetic rats

J. Singh1, F. M. Alomar2,3, K. R. Bidasee4

1. University of Central Lancashire, Preston, United Kingdom. 2. University of Nebraska Medical Center, Omaha, Nebraska, United States. 3. University of Dammam, Dammam, Saudi Arabia. 4. 5Nebraska Redox Biology Center, Lincoln, Nebraska, United States.

Diabetic heart failure (dHF) is an established cause of morbidity and mortality in individuals with diabetes mellitus (DM). Supra-physiologic production/flux of the alpha-oxoaldehyde methylglyoxal (MG) has emerged as likely candidate since it can promote mitochondrial dysfunction, a known cause of dHF. In this study which was approved by the Animal Care and Use Committee, University of Nebraska Medical Center, a custom-designed adeno-associated virus in conjunction with echocardiography, electron, atomic force and electro-paramagnetic resonance spectroscopies, live cell imaging, Western blot analyses and high performance liquid chromatography was used to determine if preventing supra-physiologic MG in DM rat hearts is mitochondria and cardio-protective. After eight weeks of streptozotocin-induced DM, E:A ratio was increased and % fractional shortening and ejection fraction were reduced in 3-4% isoflurane-anesthetized rats, indicative of dHF. Rats were then sacrificed by injecting with Inactin (Sodium thiopental, 120 mg/kg, i.p) and hearts were harvested. In ultrathin ventricular sections from DM hearts, SSM were no longer thread-like but disjointed from each other and migrated away from the plasma membrane (~5 nm). Purified SSM from DM hearts were also smaller (850 ± 20 nm, compared to 1090 ± 25 nm for control) with more compact, lamelliform cristae (21 ± 4 nm compared to 28 ± 3 nm for control), and generated ~2.5X higher basal reactive oxygen species (ROS)/µg mitochondria. Isolated SSM and SSM in ventricular tissues also contained single and double membraned mitochondrial-derived vesicles, suggesting extrusion of oxidized cargoes. Isolated SSM also contained ~50% less connexin 43 and superoxide dismutase-1 (SOD-1), and ~ 2X more dynamin-1-like protein (Drp-1) and mitofusin II (mfn-2). NDUF2, 3 and 10 contained ~ 2-3X more MG adduct on them compared to controls. Preventing Glo-I downregulation in DM rats by administering an AAV2/9 containing Glo-I driven by the endothelin-1 promoter one week after the onset of DM, attenuated impairments in E:A ratio, % fractional shortening and ejection fraction later in the disease (7-8 weeks). It also attenuated changes in structure and function of SSM induced by DM. These data show for the first time that supra-physiologic MG flux is an underlying cause of SSM dysregulation in hearts of DM rats. They also show that attenuating supra-physiologic MG flux by preventing Glo-I downregulation is sufficient to blunt SSM dysregulation and HF in DM.

Where applicable, experiments conform with Society ethical requirements