An immortalized jimpy oligodendrocyte cell line: Defects in cell cycle andcAMP pathway

Normal and jimpy oligodendrocytes in secondary cultures were transfected wi th plasmids containing the SV40 T-antigen gene expressed under the control of the mouse metallothionein-I promoter. Two immortalized stable cell lines , a normal (158N) and jimpy (158JP) cell line, expressed transcripts and pr oteins of oligodendrocyte markers, including proteolipid protein (PLP), mye lin basic protein (MBP), and carbonic anhydrase II (CAII). Galactocerebrosi de and sulfatide were also detected with immunocytochemistry. Immunoelectro n microscopy using gold particles showed that the truncated endogenous jimp y PLP was distributed throughout the cytoplasm and in association with the plasma membrane of cell bodies and processes. The length of the cell cycle in the jimpy oligodendrocytes in the absence of zinc was 31 h, about a 4-h longer cell cycle than the normal line. In the presence of 100 muM zinc, th e cell cycle became 3 h shorter for both cell lines, with the jimpy cell cy cle duration remaining 4 h longer than the normal line. Interestingly, the jimpy cell line showed a significant deficiency in stimulation via the cAMP pathway. While the level of oligodendrocyte markers (PLP, MBP, and CAII) w ere significantly increased by dibutyryl cAMP (dbcAMP) treatment in the nor mal cell line, no changes were observed in the jimpy cell lines. This obser vation, together with previous results showing jimpy oligodendrocyte's fail ure to respond to basic fibroblast growth factor (bFGF), suggests a role fo r PLP in a signal transduction pathway. Jimpy and normal oligodendrocytes t ransfected with the SV40T antigen gene, driven by the wild-type promoter of mouse metallothionein-I, continue to express properties of oligodendrocyte s and therefore provide a powerful model to explore the function of myelin proteins and to dissect the complexity of the jimpy phenotype. (C) 2001 Wil ey-Liss, Inc.