In vitro death of jimpy oligodendrocytes: Correlation with onset of DM-20/PLP expression and resistance to oligodendrogliotrophic factors

Abstract

Severe hypomyelination in the jimpy (jp) mouse mutation results from premature death of most oligodendrocytes (OCs). We have applied an immunopanning technique to successfully purify oligodendroblasts (OBs) directly from neonatal jp brainstem in order to determine if their death during differentiation into OCs is preventable in culture by diffusible oligodendrogliotrophic factors. No significant differences in the yield (0.9-1.1 x 10(5) cells/brainstem) or viability (approximately 90%) of OB populations from jp and wild-type (wt) littermates were observed, indicating that cell death occurs at a later stage in the mutant lineage. When cultured in a basally defined, insulin-containing medium, wt and jp OBs died 1-2 days later as their differentiation into GalC+ OCs began. Survival was not enhanced by known trophic factors (ciliary neurotrophic factor, leukemia inhibitory factor, neurotrophin-3) for differentiating rat OCs. In medium conditioned by neonatally derived rat or wt mouse astrocytes, however, wt OBs survived terminal OC differentiation, expressing first GalC, then DM-20/PLP on their surface 1-2 days later, before elaborating myelin-like membrane. By contrast, jp OBs in sister cultures survived differentiation initially as well as their normal counterparts did but rapidly died thereafter, beginning at the time when PLP/DM-20 immunoreactivity became detectable on premature wt GalC+ OCs. Additionally under these conditions, there survived a minor population (<5%) of jp cells, including mature OCs, which expressed stunted membranes and DM-20/PLP immunoreactivity in their cytoplasm, and undifferentiated progenitors. This model supports the concept that OC death in jp is effected by an intrinsic program, one mechanistically related to jp PLP/DM-20 gene expression and refractory to trophic cues in the environment.

Cell death in the oligodendrocyte lineage: A molecular perspective of life/death decisions in development and disease

“…In support of this view, mice lacking p53 are resistant to myc-induced death and overexpression of p53 in the oligodendrocyte lineage is sufficient to induce an apoptotic program (Eizenberg et al, 1996). In general, however, it is very important to distinguish between manipulation of the intrinsic cell cycle machinery (either using transgenic approaches or viralmediated gene transfer) and conflicting growth factor Optic nerve Barres et al, 1992Burne et al, 1996Raff et al, 1993Developing cortex and hippocampus Trapp et al, 1997Bertollini et al, 1997Spinal cord Calver et al, 1998 Loss of trophic support Barres et al, 1993Cohen et al, 1996Dell'Albani et al, 1998Kumar et al, 1998., jimpy mice, md rats) Grinspan et al, 1998Knapp et al, 1990, 1999Lipsitz et al, 1998Vermeesh et al, 1990Williams and Gard, 1997Transgenics Jensen et al, 1998. Oligodendrocyte cell death in pathological conditions…”

Current concepts of PLP and its role in the nervous system

“…Spontaneous mutations of the Plp gene are associated with increased death of oligodendrocytes in vivo (Knapp et al, 1986) and this feature can be partially ameliorated in jimpy mice by providing wild type PLP through transgenic complementation (Schneider et al, 1995). Similarly, death of jimpy oligodendrocytes in culture has been linked to expression of the Plp gene (Williams and Gard, 1997). Spontaneous Plp mutations, such as rumpshaker, with higher levels of DM20 are associated with less cell death (Mitchell et al, 1992;Schneider et al, 1992) than mutations such as jimpy in which PLP/DM20 are minimal or undetectable.…”

Selective specification of CNS stem cells into oligodendroglial or neuronal cell lineage: Cell culture and transplant studies

“…The cells were counted using hemocytometry and plated onto freshly coated dishes (2 × 10 6 cells/100 mm dish). Immunopanning was used to select specific populations of cells using either 50 μg/ml anti‐PSA‐NCAM (Developmental Studies Hybridoma Bank, University of Iowa) or 25 μg/ml anti‐IgM antibody (Sigma, St. Louis, MO) (Wysocki and Sato, 1978; Williams and Gard, 1997). In previous studies, we characterized the role of different substrates (plates coated with antibody to either A2B5, IgM, or PSA‐NCAM) and found that for cells isolated from animals of this age, both PSA‐NCAM and IgM‐coated plates selected for stem cells.…”