Dihydroorotate Dehydrogenase as a Modulator of Ferroptosis in Myocardial Ischemia-Reperfusion Injury.

Introduction: Ferroptosis is increasingly acknowledged as a pivotal contributor to myocardial cell injury in ischemia-reperfusion (I/R). As a central enzyme in the pyrimidine synthesis pathway, dihydroorotate dehydrogenase (DHODH) is implicated in maintaining redox homeostasis and is thought to act as a protective agent against ferroptosis. Despite this association, the specific contributions of DHODH to myocardial ischemia-reperfusion injury (MIRI) and its cardioprotective potential remain inadequately elucidated.

Aim: This study aimed to delineate the role of DHODH in MIRI and assess its capacity to modulate ferroptosis in cardiomyocytes.

Methods: We utilized AC16 cardiomyocytes to establish an in vitro MIRI model to investigate the role of DHODH in ferroptosis. We quantitatively analyzed DHODH expression during I/R injury, along with its distribution in cytoplasmic and mitochondrial compartments. Cells pretreated with dihydroorotate (DHO) and orotate (OA)-the substrate and product of DHODH, respectively-provided a basis for assessing their susceptibility to ferroptosis. By employing siRNA to suppress DHODH expression, we delved into the underlying mechanisms of DHODH's protective role against I/Rinduced ferroptosis, focusing on oxidative stress and mitochondrial dysfunction.

Results: Our findings reveal a significant induction of DHODH expression during ferroptosis in the AC16 I/R model. DHO pretreatment conferred resistance to ferroptosis, while OA pretreatment rendered cells more susceptible. Notably, DHODH silencing aggravated ferroptosis indicators, mainly through increased oxidative stress and mitochondrial dysfunction.

Conclusion: DHODH emerges as a key modulator of ferroptosis in the context of MIRI, offering protection predominantly through its antioxidative functions and maintenance of mitochondrial integrity.