Role of Dynamin Related Protein 1 (Drp1)-Mediated Mitochondrial Fission in Oxygen-Sensing and Constriction of the Ductus Arteriosus
Rationale: Closure of the ductus arteriosus (DA) is essential for the transition from fetal to neonatal patterns of circulation. Initial PO2-dependent vasoconstriction causes functional DA closure within minutes. Within days a fibrogenic, proliferative mechanism causes anatomical closure. Though modulated by endothelial-derived vasodilators and constrictors, O2-sensing is intrinsic to ductal smooth muscle cells (DASMC) and oxygen-induced DA constriction persists in the absence of endothelium, endothelin and cyclooxygenase mediators. O2 increases mitochondrial-derived H2O2 (mitoROS), which constricts DASMC by raising intracellular calcium and activating rho kinase. However, the mechanism by which oxygen changes mitochondrial function is unknown.
Objective: Determine whether mitochondrial fission is crucial for O2-induced DA constriction and closure.
Methods and Results: Using DA harvested from 30 term infants during correction of congenital heart disease, as well as DA from term rabbits, we demonstrate that mitochondrial fission is crucial for O2-induced constriction and closure. O2 rapidly (<5 minutes) causes mitochondrial fission by a cyclin-dependent kinase-mediated phosphorylation of dynamin-related protein 1 (Drp1) at serine 616. Fission triggers a metabolic shift in the DASMC that activates pyruvate dehydrogenase and increases mitochondrial H2O2 production. Subsequently fission increases complex I activity. Mitochondrial-targeted catalase overexpression eliminates PO2-induced increases in mitoROS and cytosolic calcium. The small-molecule Drp1 inhibitor, Mdivi-1, and siDRP1 yield concordant results, inhibiting O2-induced constriction (without altering the response to phenylephrine or KCl) and preventing O2-induced increases in oxidative metabolism, cytosolic calcium and DASMC proliferation. Prolonged Drp1 inhibition reduces DA closure in a tissue culture model.
Conclusions: Mitochondrial fission is an obligatory, early step in mammalian O2-sensing and offers a promising target for modulating DA patency.
- oxygen sensing
- persistent patent ductus arteriosus
- mitochondrial division inhibitor-1 (Mdivi-1)
- mitochondrial-targeted photoactivatable green fluorescent protein
- cyclin-dependent kinase
- ductus arteriosus
- oxygen consumption
- cell signaling
- Received October 11, 2012.
- Revision received January 16, 2013.
- Accepted January 18, 2013.
- Copyright © 2013, Circulation Research