Sulfatide species with various fatty acid chains in oligodendrocytes at different developmental stages determined by imaging mass spectrometry

Abstract

HSO3-3-galactosylceramide (Sulfatide) species comprise the major glycosphingolipid components of oligodendrocytes and myelin and play functional roles in the regulation of oligodendrocyte maturation and myelin formation. Although various sulfatide species contain different fatty acids, it is unclear how these sulfatide species affect oligodendrogenesis and myelination. The O4 monoclonal antibody reaction with sulfatide has been widely used as a useful marker for oligodendrocytes and myelin. However, sulfatide synthesis during the pro-oligodendroblast stage, where differentiation into the oligodendrocyte lineage has already occurred, has not been examined. Notably, this stage comprises O4-positive cells. In this study, we identified a sulfatide species from the pro-oligodendroblast-to-myelination stage by imaging mass spectrometry. The results demonstrated that short-chain sulfatides with 16 carbon non-hydroxylated fatty acids (C16) and 18 carbon non-hydroxylated fatty acids (C18) or 18 carbon hydroxylated fatty acids (C18-OH) existed in restricted regions of the early embryonic spinal cord, where pro-oligodendroblasts initially appear, and co-localized with Olig2-positive pro-oligodendroblasts. C18 and C18-OH sulfatides also existed in isolated pro-oligodendroblasts. C22-OH sulfatide became predominant later in oligodendrocyte development and the longer C24 sulfatide was predominant in the adult brain. Additionally, the presence of each sulfatide species in a different area of the adult brain was demonstrated by imaging mass spectrometry at an increased lateral resolution. These findings indicated that O4 recognized sulfatides with short-chain fatty acids in pro-oligodendroblasts. Moreover, the fatty acid chain of the sulfatide became longer as the oligodendrocyte matured. Therefore, individual sulfatide species may have unique roles in oligodendrocyte maturation and myelination. Read the Editorial Highlight for this article on page 356.

Dynamics of sphingolipids and the serine-palmitoyltransferase complex in oligodendrocytes during myelination

“…We and others observe that as myelination progresses there is a decline in the levels of long chain (16:0 and 18:0)-containing sphingolipids (44,46) and a corresponding increase in the very long chain sphingolipids (principally 24:0 and 24:1). In our studies this is less apparent in the total brain lipids such as ceramides and sphingomyelin, but readily seen in the myelin-enriched monohexosylceramides in total brain samples as well in all sphingolipids measured in isolated oligodendrocytes.…”

The human UDP-galactose 4’-epimerase (GALE) is required for cell surface glycome structure and function

“…2B). GM3 ganglioside is a regulator of leptin signaling and has been linked to development of insulin resistance (63,64), sulfatides are major components of myelin and are believed to play crucial roles in neuronal differentiation (65,66) and deficiencies in LacCer biosynthesis cause locomotor deficits and abnormal brain development in mice (67). Therefore, GALE-dependent glycolipid biosynthesis may be required for normal nutrient responses and neuronal physiology in vivo.…”

Early glycolipid (POA) in pro‐oligodendroblasts revealed to be sulfatide

“…In this issue, Hirahara et al . (), have used mass spectrometry techniques on pro‐oligodendroblasts in culture and in embryonic spinal cord to show that the pro‐oligodendroblast antigen that reacts with O4 antibody in early stage oligodendrocytes is indeed sulfated galactosylceramide. This is a very important finding because of the essential roles of these glycosphingolipids in oligodendrocytes and myelin.…”

“…The fatty acid chain length and the ratio of hydroxylated to non‐hydroxylated species of sulfatide was known to increase in the brain with age (Svennerholm and Ställberg‐Stenhagen ; Shimomura and Kishimoto ) but the study by Hirahara et al . () is the first to characterize the molecular species of sulfatide in oligodendrocytes at different stages.…”

“…Hirahara et al . () used imaging mass spectrometry techniques to detect sulfatide with short chain fatty acids, C16, C18, and C18:0H in pro‐oligodendroblasts at embryonic stages, thus showing that sulfatide is the glycolipid, POA , that reacts with O4 monoclonal antibody. The sulfatide species vary with cell development and in myelin, with increased chain length to 22 carbons in more mature pro‐oligodendroblasts at a later embryonic stage, and to 24 carbons, with and without a double bond and an alpha hydroxyl group, C24:0, C24:1, C24‐ OH , and C24:1‐ OH , in myelin.…”