Mitochondrial dysfunction resulting from the down-regulation of bone morphogenetic protein 5 may cause microtia

BACKGROUND: Bone morphogenetic protein 5 (BMP5) has been identified as one of the important risk factors for microtia; however, the link between them has yet to be clarified. In this study, we aimed to demonstrate the relationship of BMP5 with mitochondrial function and investigate the specific role of mitochondria in regulating microtia development. METHODS: BMP5 expression was measured in auricular cartilage tissues from patients with and without microtia. The effects of BMP5 knockdown on cellular function and mitochondrial function were also analyzed in vitro. Changes in genome-wide expression profiles were measured in BMP5-knockdown cells. Finally, the specific impact of BMP5 down-regulation on mitochondrial fat oxidation was analyzed in vitro. RESULTS: BMP5 expression was down-regulated in the auricular cartilage tissues of microtia patients. BMP5 down-regulation inhibited various cellular functions in vitro, including cell proliferation, mobility, and cytoactivity. The functional integrity of mitochondria was also damaged, accompanied by a decrease in mitochondrial membrane potential, reactive oxygen species (ROS) neutralization, and reduced adenosine triphosphate (ATP) production. Carnitine O-palmitoyltransferase 2 and diacylglycerol acyltransferase 2, two of the key regulators of mitochondrial lipid oxidation, were also found to be decreased by BMP5 down-regulation. CONCLUSIONS: Down-regulation of BMP5 affects glycerolipid metabolism and fatty acid degradation, leading to mitochondrial dysfunction, reduced ATP production, and changes in cell function, and ultimately resulting in microtia. This research provides supporting evidence for an important role of BMP5 down-regulation in affecting mitochondrial metabolism in cells, and sheds new light on the mechanisms underlying the pathogenesis of microtia.