Neuroprotective effects of melatonin-mediated mitophagy through nucleotide-binding oligomerization domain and leucine-rich repeat-containing protein X1 in neonatal hypoxic-ischemic brain damage.

Hypoxia-ischemia (HI) is a major cause of brain damage in neonates. Mitochondrial dysfunction acts as a hub for a broad spectrum of signaling events, culminating in cell death triggered by HI. A neuroprotective role of melatonin (MT) has been proposed, and mitophagy regulation seems to be important for cell survival. However, the molecular mechanisms underlying MT-mediated mitophagy during HI treatment are poorly defined. Nucleotide-binding oligomerization domain and leucine-rich repeat-containing protein X1 (NLRX1) has emerged as a critical regulator of mitochondrial dynamics and neuronal death that participates in the pathology of diverse diseases. This study aimed to clarify whether NLRX1 participates in the regulation of mitophagy during MT treatment for hypoxic-ischemic brain damage (HIBD). We demonstrated that MT protected neonates from HIBD through NLRX1-mediated mitophagy in vitro and in vivo. Meanwhile, MT upregulated the expression of NLRX1, Beclin-1, and autophagy-related 7 (ATG7) but decreased the expression of the mammalian target of rapamycin (mTOR) and translocase of the inner membrane of mitochondrion 23 (TIM23). Moreover, the neuroprotective effects of MT were abolished by silencing NLRX1 after oxygen-glucose deprivation (OGD). In addition, the downregulation of mTOR and upregulation of Beclin-1 and ATG7 by MT were inhibited after silencing NLRX1 under OGD. In summary, MT modulates mitophagy induction through NLRX1 and plays a protective role in HIBD, providing insight into potential therapeutic targets for MT to exert neuroprotection.