Spatiotemporal Heterogeneity of Sulfatide Molecular Species During Schwann Cell Development in the Peripheral Nervous System.

Sulfatide (3-O-sulfogalactosylceramide) is a major glycolipid component of myelin synthesized by oligodendrocytes in the central nervous system (CNS) and Schwann cells (SCs) in the peripheral nervous system (PNS). Although sulfatide diversity has been characterized in CNS myelin, its species-level composition, spatial organization, and developmental dynamics in the PNS remain poorly defined. Here, we used imaging mass spectrometry (IMS) to characterize sulfatide molecular species in murine dorsal root ganglia (DRGs) during development. Thirteen sulfatide species were identified in adult DRGs and classified as long-chain (LC) or very-long-chain (VLC), with hydroxylated or non-hydroxylated forms. VLC non-hydroxylated sulfatides were preferentially enriched in compact myelin-rich regions, whereas LC and hydroxylated species exhibited broader distributions extending into neuronal soma-associated regions. Multivariate analyses further demonstrated that regional sulfatide molecular species profiles were associated with fatty acyl chain length and hydroxylation status. Developmentally, structurally diverse sulfatide classes, including LC non-hydroxylated, VLC non-hydroxylated, and VLC hydroxylated species, were detectable by embryonic day 14.5, and all species were present by postnatal day 2, indicating that sulfatide diversification is established before mature myelin formation. Sulfatide species exhibited ventral enrichment within developing DRGs, a pattern partially conserved in chick embryos. Analysis of Cst-null mice confirmed previously reported abnormalities in myelinating SC-axon units and further revealed defective Remak bundle organization characterized by incomplete axonal ensheathment, together with altered dynamics of Sox10+/Sox2+ SCs. These findings reveal a previously unrecognized spatiotemporal heterogeneity of sulfatide species in the developing PNS and support roles for sulfatide diversity in SC maturation and peripheral nerve organization.