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PubMed2006

Nuclear reprogramming by cell fusion.

The use of cell fusion to study exchange of information at the molecular level between the nucleus and the cytoplasm of cells during regulation of gene expression was pioneered by Harris and Ringertz more than three decades ago. The ability to make heterokaryons with cells from different species or genetic strains is especially useful because genetic differences in gene products allow the origin of trans-acting regulatory factors to be determined. Heterokaryons between adult nucleated erythroid cells of one species and embryonic/larval nucleated erythroid cells of another species, for example, show cross-induction between the two types of nuclei, resulting in reprogramming of the adult nucleus to embryonic/larval globin gene expression and/or reprogramming of the embryonic/larval cell nucleus to adult globin expression. These experiments provided definitive evidence that developmental program switching is mediated by trans-acting factors. Other possible uses of this cell fusion protocol in stem cell biology and transplantation of genetically engineered cells for tissue regeneration are briefly discussed.

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PubMedDate not supplied

Demyelination and remyelination after spinal cord injury.

Since the discovery in the 1960s that remyelination can occur in the damaged central nervous system (CNS) (Bunge et al. 1961), there has been much progress in understanding the cellular and molecular biology of oligodendroglia and the factors that regulate their propagation, migration, differentiation, maturation, and ability to myelinate nerve axons. More recently, greater understanding of disease states and the role of oligodendrocytes in remyelination have sparked tremendous interest in this once obscure field. Although the explosion of information is being hampered by adherence to commonly held beliefs based on empirical evidence, novel molecular and cellular tools are allowing scientists to address age-old assumptions. It is now recognized that, as well as promoting salutatory conduction along axons, oligodendroglia are important near-term clinical targets for restoring function after CNS injury, particularly spinal cord injury. Thus, remyelination appears to be one of the most feasible restoration strategies. This review focuses on concepts that are important for developing strategies of repair. The brightest young scientists will be attracted into this exciting field by its near-term potential for human application.

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