749 - Cyclophilin D-mitochondria-ROS-differentiation pathway regulates neonatal heart bioenergetics and function

Sunday, April 30, 2023

3:30 PM – 6:00 PM ET

Poster Number: 749
Publication Number: 749.304

Hope Kile, Golisano Children's Hospital at The University of Rochester Medical Center, Rochester, NY, United States; Joshua Y.. Agyarko, University of Rochester School of Medicine and Dentistry, Yonkers, NY, United States; Gisela Beutner, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States; George A. Porter, Golisano Children's Hospital at The University of Rochester Medical Center, Rochester, NY, United States

Presenting Author(s)

Hope Kile, MD (she/her/hers)

Resident
Golisano Children's Hospital at The University of Rochester Medical Center
Rochester, New York, United States

Background: Birth is the most rapid, dynamic transition that an individual will have to undergo during a lifetime and the neonatal heart adapts from a lower pressure system to a sudden high cardiac output system. Mitochondria and the closure of the mitochondrial permeability transition pore (mPTP) are vital to this process. The mPTP is controlled by cyclophilin D (CyPD), and inhibition or knockout of CyPD increases differentiation of embryonic cardiomyocytes, closes the mPTP, and decreases the generation of reactive oxygen species (ROS).

Objective:

Major gaps still exist regarding the CyPD-ROS-differentiation pathway. By determining how ROS control the final myocardial differentiation process, we can better understand and eventually provide treatments for neonates with congenital heart disease to manipulate differentiation and boost cardiac function.

Design/Methods: Neonatal C57Bl6 mice were intraperitoneally injected on day 1-6 of with Mitoparaquat (mPQ; 0.025-0.05 mg/kg), Paraquat (PQ; 2.5-5 mg/kg), Tempol (0.7 mg/kg), MitoTempo (mT; 0.7 mg/kg), Dinitrophenol (DNP; 2 mg/kg) or vehicle (Veh, PBS). Hearts were harvested the day after the last injection and mitochondrial respiration, the enzymatic activity of the electron transport chain complexes 1 and 2, and the prevalence of mitochondrial supercomplexes were measured.

Results:

Treatment with mPQ or PQ led to a dose-dependent decrease of the respiratory control ratio (RCR) with complex (Cx) 1 substrates. The CyPD inhibitor cyclosporine A was not protective. In gel assays for Cx I demonstrate a decrease of the ratio respirasomes to Cx I monomer in mPQ and PQ, but not in mT treated hearts. In gel assay activity for a combined Cx 3 and 4 assay shows an increase of the respirasome/monomer ratio of Cx 3 for mT treated mice.

NADH oxidase and NADH-ubiquinone oxido-reductase activities of Cx 1 show, relative to vehicle treated mice, a decrease in mPQ, PQ, and Tempol treated mice, with no effect on DNP and mT treated mice. Cx 2 activity in these samples showed no significant differences. Western blots for both WT and CyPD knockout mice treated with mPQ and PQ indicate a dose dependent decrease of the detection of proteins of the electron transport chain.

Conclusion(s): Treating neonatal mice with mPQ and PQ decreases respiratory activity, respirasomes and Cx 1 activity in the heart. This demonstrates that the formation and functionality of respirasomes depends on ROS and increasing ROS in cardiomyocytes could delay final differentiation, thereby extending a window for treatment of infants born with congenital heart disease.