Oligodendroblasts Distinguished from O-2A Glial Progenitors by Surface Phenotype (O4+GalC-) and Response to Cytokines Using Signal Transducer LIFRβ

AbstractThe developmental potential of progenitors at two final stages of the macroglial lineage giving rise to oligodendrocytes in postnatal rat brain was studied in response to defined and serum inducers of astrocyte gene expression. Cell immunoselection [with GD3 ganglioside, 04 and galactocerebroside (GalC) antibodies] was used to isolate G+D3O4- and O4+GalC- phenotypes directly from premyelinating cerebrum. In a basal defined culture medium, G+D3O4- progenitors differentiated infrequently into oligodendrocytes on a growth substratum comprised of meningeal cell-derived extracellular matrix. Their conversion into astrocytes, as determined by immunofluorescence analysis of glial fibrillary acidic protein expression, was induced by oncostatin-M as well as leukemia inhibitory factor (LIF) and ciliary neurotrophic factor, but not interleukin-6, and required extracellular matrix. By comparison, O4+GalC- progenitors were refractory to astrocyte induction under these conditions, as in short-term cultures of optic nerve. and differentiated into myelinogenic oligodendrocytes instead. Only in response to an overriding stimulus in fetal bovine serum did O4+GalC- progenitors, like their immediate precursors, become astrocytic. These data functionally distinguish two classes of astrocyte-inducing agents to provide clear evidence of an oligodendroblast, a progenitor defined by surface phenotype (O4+GalC-) and an altered response of the oligodendrocyte lineage to cytokines using signal transducer LIFRβ

A non‐transformed oligodendrocyte precursor cell line, OL‐1, facilitates studies of insulin‐like growth factor‐I signaling during oligodendrocyte development

The process by which oligodendrocyte progenitors differentiate into mature oligodendrocytes is complex and incompletely understood in part because of the paucity of oligodendrocyte precursors cell lines that can be studied in culture. We have developed a non-immortalized rat oligodendrocyte precursor line, called OL-1, which behaves in a fashion consistent with developing oligodendrocytes in vivo. This OL-1 line provides a model for the study of oligodendrocyte development and offers an alternative to the CG-4 cell line. When OL-1 cells are propagated in conditioned growth media, they have morphology consistent with immature oligodendrocytes and exhibit A2B5 antigen positive and myelin basic protein-negative immunoreactivity. Withdrawal of conditioned growth media and culture in serum-free medium results in OL-1 cell maturation, manifested by a shift to myelin basic protein-positive immunoreactivity, A2B5 antigen-negative immunoreactivity, decreased NG2 mRNA expression, increased expression of proteolipid protein mRNA, and increased expression of CNP protein. In addition, the expression of proteolipid protein and its splicing variant DM-20 exhibit a pattern that is similar to brain proteolipid protein expression during development. When OL-1 cells are exposed to Insulin-like growth factor-I, there are significant increases in proteolipid protein mRNA expression ( p < 0.05), the number of cell processes ( p < 0.05), and cell number ( p < 0.05). Treatment with the caspase inhibitors Z-DEVD-FMK and Z-VAD-FMK (inhibitors of caspases 3, 6, 7, 8, 10 and 1, 3, 4, respectively), Insulin-like growth factor-I, or both, results in a similar increase in cell number. Because Insulin-like growth factor-I does not substantially increase the BrdU labeling of OL-1 cells, these data collectively indicate that Insulin-like growth factor-I increases OL-1 cell number predominately by promoting survival, rather than stimulating proliferation. This non-immortalized oligodendrocyte precursor cell line, therefore, exhibits behavior consistent with the in vivo development of oligodendrocytes and provides an excellent model for the study of developing oligodendrocytes