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J. Cell Biol.,
Volume 142, Number 1, July 13, 1998 203-216
/RPTP
and Its Ligand Pleiotrophin/Heparin-binding Growth-associated
Molecule (HB-GAM) in Neuronal Migration
Division of Molecular Neurobiology, National Institute for Basic Biology, and Department of Molecular Biomechanics, The
Graduate University for Advanced Studies, Okazaki 444-8585, Japan
Pleiotrophin/heparin-binding growth-associated molecule (HB-GAM) is a specific ligand of protein tyrosine phosphatase
(PTP
)/receptor-like protein tyrosine phosphatase
(RPTP
) expressed in the
brain as a chondroitin sulfate proteoglycan. Pleiotrophin
and PTP
isoforms are localized along the radial glial fibers, a scaffold for neuronal migration, suggesting that
these molecules are involved in migratory processes of
neurons during brain development. In this study, we examined the roles of pleiotrophin-PTP
interaction in
the neuronal migration using cell migration assay systems with glass fibers and Boyden chambers. Pleiotrophin and poly-L-lysine coated on the substratums stimulated cell migration of cortical neurons, while laminin,
fibronectin, and tenascin exerted almost no effect. Pleiotrophin-induced and poly-L-lysine-induced neuronal migrations showed significant differences in sensitivity to various molecules and reagents. Polyclonal
antibodies against the extracellular domain of PTP
,
PTP
-S, an extracellular secreted form of PTP
, and sodium vanadate, a protein tyrosine phosphatase inhibitor, added into the culture medium strongly suppressed
specifically the pleiotrophin-induced neuronal migration. Furthermore, chondroitin sulfate C but not chondroitin sulfate A inhibited pleiotrophin-induced neuronal migration, in good accordance with our previous
findings that chondroitin sulfate constitutes a part of
the pleiotrophin-binding site of PTP
, and PTP
-pleiotrophin binding is inhibited by chondroitin sulfate
C but not by chondroitin sulfate A. Immunocytochemical analysis indicated that the transmembrane forms of
PTP
are expressed on the migrating neurons especially
at the lamellipodia along the leading processes. These
results suggest that PTP
is involved in the neuronal
migration as a neuronal receptor of pleiotrophin distributed along radial glial fibers.
;
pleiotrophin;
neuronal migration;
receptor-like protein tyrosine phosphatase;
proteoglycan
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