The long term goal of our studies is to elucidate the mechanisms whereby polypeptide growth factors regulate the development of oligodendrocytes, the myelin forming cell of the CNS. These issues are important in order to understand the mechanisms underlying disorders affecting CNS myelin, and for devising strategies for intervention including promoting regeneration by endogenous repair, or transplanting cells to supplement this repair. The specific focus of this proposal is to anlyze the functionally important domains of the Platelet Derived Growth Factor alpha-receptor (PDGFRalpha) that modulate the biological responses of oligodendrocytes to PDGF. The purpose of these experiments is to determine how oligodendrocytes generate diverse biological responses from a single growth factor. PDGF is one of at least seven ligands acting via receptors with tyrosine kinase activity that affect oligodendrocyte development, and has a diverse range of effects including the ability to modulate proliferation, migration, differentiation and survial. The fundamental question addressed in this proposal is whether specific domains of PDGFRalpha, associated with distinct signaling pathways, are linked to separate biological responses of oligodendrocyte progenitors to PDGD. This hypothesis will be addressed using a combination of in vitro and in vivo approaches. First, expression vectors encoding mutant versions of PDGFRalpha will be transfected into primary oligodendrocyte progenitors, which will then be examined for PDGFRalpha transgene-meditaed biological reponses in vitro. The PDGFRalpha transgenes are engineered to be specifically activated by a neutral ligand (hCSF-1) and include mutations in domains of PDGFRalpha that block activation of individual second messenger pathways. Second, mutated PDGFRalpha cDNAs will be introduced into progenitor cells isolated from PDGFRalpha-null mice, and the effects of specific mutations on oligodendrocyte development will be analyze after transplantation in vivo. Third signaling pathways activated by PDGF will be characterizing by RNA transcript analysis. These experiments should (I) identify the intra-cellular domains of PDGFRalpha, and signal transduction pathways associated with these domains, regulating the proliferation, migration, differentiation and survival of oligodendrocyte progenitors, and (ii) whether individual domains are associated with these specific biological responses, in vitro and in vivo.
| Kiel, Mary E; Chen, Cui P; Sadowski, Dorota et al. (2008) Stem cell-derived therapeutic myelin repair requires 7% cell replacement. Stem Cells 26:2229-36 |
| Chen, Cui P; Kiel, Mary E; Sadowski, Dorota et al. (2007) From stem cells to oligodendrocytes: prospects for brain therapy. Stem Cell Rev 3:280-8 |
| McKinnon, Randall D; Waldron, Sean; Kiel, Mary E (2005) PDGF alpha-receptor signal strength controls an RTK rheostat that integrates phosphoinositol 3'-kinase and phospholipase Cgamma pathways during oligodendrocyte maturation. J Neurosci 25:3499-508 |
