A comprehensive profiling of sulfatides in myelin from mouse brain using liquid chromatography coupled to high-resolution accurate tandem mass spectrometry

Sulfatides are sulfoglycolipids found in the myelin sheath. The composition ratio of sulfatide molecular species changes with age, and it has also been associated with the pathogenesis of various human central nervous system diseases. However, profiling sulfatides in biological samples is difficult, due to the great variety of molecular species. In this work, a new, easy and reliable liquid chromatography-electrospray tandem mass spectrometry (LC-ESI(+)-MS/MS) method has been developed to profile sulfatide content in biological samples of myelin. The 'wrong-way-round' ionization effect has been described for this type of molecules for the first time, making it possible to correctly identify as many as 37 different sulfatides in mouse brain myelin samples, including molecules with different fatty acid chain lengths and varying degrees of unsaturation and hydroxylation. A chemometric analysis of their relative abundances showed that the main difference among individuals of different ages was the content of sulfatides with odd-numbered fatty acid chains, in addition to hydroxylated species.

Inhibition of endogenous phosphodiesterase 7 promotes oligodendrocyte precursor differentiation and survival

During the development of the central nervous system (CNS), oligodendrocyte precursors (OPCs) are generated in specific sites within the neural tube and then migrate to colonize the entire CNS, where they differentiate into myelin-forming oligodendrocytes. Demyelinating diseases such as multiple sclerosis (MS) are characterized by the death of these cells. The CNS reacts to demyelination and by promoting spontaneous remyelination, an effect mediated by endogenous OPCs, cells that represent approximately 5-7 % of the cells in the adult brain. Numerous factors influence oligodendrogliogenesis and oligodendrocyte differentiation, including morphogens, growth factors, chemotropic molecules, extracellular matrix proteins, and intracellular cAMP levels. Here, we show that during development and in early adulthood, OPCs in the murine cerebral cortex contain phosphodiesterase-7 (PDE7) that metabolizes cAMP. We investigated the effects of different PDE7 inhibitors (the well-known BRL-50481 and two new ones, TC3.6 and VP1.15) on OPC proliferation, survival, and differentiation. While none of the PDE7 inhibitors analyzed altered OPC proliferation, TC3.6 and VP1.15 enhanced OPC survival and differentiation, processes in which ERK intracellular signaling played a key role. PDE7 expression was also observed in OPCs isolated from adult human brains and the differentiation of these OPCs into more mature oligodendroglial phenotypes was accelerated by treatment with both new PDE7 inhibitors. These findings reveal new roles for PDE7 in regulating OPC survival and differentiation during brain development and in adulthood, and they may further our understanding of myelination and facilitate the development of therapeutic remyelination strategies for the treatment of MS.

[Oligodendrocytes: their embryonic origin, migration and therapeutic implications]

INTRODUCTION

Oligodendrocyte precursor cells are generated within specific domains in the neural tube, and from there they migrate to their final destination. Once this is reached, they will differentiate into adult oligodendrocytes, which are the cells responsible for myelination in the central nervous system. The oligodendrocyte precursors conserve a certain capacity to proliferate and have an important capacity to migrate in response to specific signals. A number of different signals are involved in the migration of these cells, although they can be divided fundamentally into two groups: adhesion molecules and secretable molecules.

DEVELOPMENT

Data concerning the known effects of different molecules involved in the migration of oligodendrocyte precursor cells were collected. It is also suggested that these molecules could be useful for developing new therapies to treat demyelinating diseases such as multiple sclerosis.

CONCLUSIONS

Knowledge of the signals that guide the migration of oligodendrocyte precursors during the development is a tool that would make it possible to direct the migration of oligodendrocyte precursor cells to demyelinating lesions and, once they are there, to get them to proliferate and myelinate the lesion.