Neonatal sevoflurane exposures inhibits DHHC5-mediated palmitoylation of TfR1 in oligodendrocytes, leading to hypomyelination and neurological impairments

Introduction: Neonatal anesthesia-related neurological impairments are of significant concern, closely linked to oligodendrocyte dysfunction. However, there is a notable temporal discrepancy between the sustained development of oligodendrocytes (myelination) and the short-term vulnerability to anesthesia exposures.

Objectives: Given the significant rise in iron demand by oligodendrocytes during neonatal period, our objective was to clarify the potential roles and underlying mechanisms of iron homeostasis, particularly focusing on Transferrin Receptor 1 (TfR1), in governing the transient susceptibility to anesthesia.

Methods: Sevoflurane (3 %, 2 h/day) was administered to wildtype or Pdgfrα-Cre^ERT mice from postnatal day (P)6 to P8. Subsequently, behavioral tests, genetic modulation, co-immunoprecipitation assays, Acyl-resin assisted capture assay and single-cell RNA Sequencing were employed on P8 and/or P32.

Results: Following neonatal exposure to sevoflurane, the observed cognitive impairments and hypomyelination at P32 were attributed to iron accumulation and Ferroptosis, particularly within oligodendrocytes of the corpus callosum (CC). This Ferroptosis was mediated by enhanced endocytosis of transiently expressed TfR1, rather than its overexpression, due to inhibited palmitoylation. Among the 21 palmitoyltransferases, only Asp-His-His-Cys5 (DHHC5) was down-regulated in oligodendrocytes, reducing palmitoylation of TfR1 at the C98 cysteine site. Furthermore, specific overexpression of DHHC5 in oligodendrocytes significantly restored TfR1 endocytosis, hypomyelination, and Ferroptosis, thereby preventing neuronal Ferroptosis across multiple brain regions by decreasing iron transport, ultimately mitigating neurological impairments.

Conclusion: We discovered that decreased DHHC5 in oligodendrocytes promotes TfR1 associated Ferroptosis, resulting in hypomyelination and initiating neuronal Ferroptosis, thereby impairing cognition following neonatal sevoflurane exposures. The transiently expressed TfR1 may mediate the critical period for neonatal anesthesia vulnerability. These findings highlight the pivotal role of TfR1-associated Ferroptosis in neonatal anesthesia-associated neurotoxicity and oligodendrocyte-neuron interaction, while providing new perspect to understand temporary neurotoxicity of anesthesia. DHHC5 may represent promising therapeutic target to enhance the safety of neonatal anesthesia and iron-related oligodendrocytes disorders.

Ferroptosis; Neonatal anesthesia exposures; Oligodendrocyte; Palmitoylation; Transferrin receptor 1; palmitoyltransferase Asp-His-His-Cys5.