Tyrosine phosphatases Shp1 and Shp2 have unique and opposing roles in oligodendrocyte development.
Oligodendrocyte progenitor cells first proliferate to generate sufficient cell numbers and then differentiate into myelin-producing oligodendrocytes. The signal transduction mediators that underlie these events, however, remain poorly understood. The tyrosine phosphatase Shp1 has been linked to oligodendrocyte differentiation as Shp1-deficient mice show hypomyelination. The Shp1 homolog, Shp2, has recently been shown to regulate astrogliogenesis, but its role in oligodendrocyte development remains unknown. Here, we report that Shp2 protein levels were developmentally regulated in oligodendrocytes, with Shp2 phosphorylation being promoted by oligodendroglial mitogens but suppressed by laminin, an extracellular matrix protein that promotes oligodendroglial differentiation. In contrast, oligodendrocyte progenitors were found to be unresponsive to mitogens following Shp2, but not Shp1, depletion. In agreement with previous studies, Shp1 depletion led to decreased levels of myelin basic protein in differentiating oligodendrocytes, as well as reduced outgrowth of myelin membrane sheets. Shp2 depletion in contrast did not prevent oligodendrocyte differentiation but promoted expanded myelin membrane outgrowth. Taken together these data suggest that Shp1 and Shp2 have distinct functions in oligodendrocyte development: Shp2 regulates oligodendrocyte progenitor proliferation and Shp1 regulates oligodendrocyte differentiation. Adhesion to laminin may additionally provide extrinsic regulation of Shp2 activity and thus promote the transition from progenitor to differentiating oligodendrocyte.
Kuo
Emory
E
Department of Pharmacology, Stony Brook University, Stony Brook, New York 11794, USA.
Park
Daniel K
DK
Tzvetanova
Iva D
ID
Leiton
Cindy V
CV
Cho
Brian S
BS
Colognato
Holly
H
D000818:Animals; D000831:Animals, Newborn; D001973:Bromodeoxyuridine / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002540:Cerebral Cortex / Q000166:cytology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007797:Laminin / Q000378:metabolism; D004676:Myelin Basic Protein / Q000378:metabolism; D020890:Neuregulin-1 / Q000494:pharmacology; D009836:Oligodendroglia / Q000187:drug effects / Q000502:physiology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000235:genetics / Q000378:metabolism*; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013234:Stem Cells / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014162:Transfection
D007797:Laminin; D004676:Myelin Basic Protein; D020890:Neuregulin-1; D010982:Platelet-Derived Growth Factor; D034741:RNA, Small Interfering; D005346:Fibroblast Growth Factors; D048049:Extracellular Signal-Regulated MAP Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D010727:Phosphoric Diester Hydrolases; D001973:Bromodeoxyuridine