1997 Fiscal Year Final Research Report Summary
Analysis of the functional roles of brain-specific 6B4 proteoglycan
| Project/Area Number |
08680775
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Cell biology
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| Research Institution | (National Institute for Basic Biology) Okazaki National Research Institutes |
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Principal Investigator |
MAEDA Nobuaki National Institute for Basic Biology, Associate Professor, 基礎生物学研究所, 助教授 (90202308)
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| Project Period (FY) |
1996 – 1997
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| Keywords | proteoglycan / 6B4 proteoglycan / PTPzeta / pleiotrophin / neurite extension / neuronal migration |
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| Research Abstract |
6B4 proteoglycan/phosphacan is a brain-specific chondroitin sulfate proteoglycan, which corresponds to the extracellular domain of a receptor-like protein tyrosine phosphatase, PTPzeta/RPTPbeta. 6B4 proteoglycan and PTPzeta are generated by alternative splicing. In this study, I identified a ligand molecule of PTPzeta, and analyzed the functional roles of PTPzeta. A 18 kDa 6B4 proteoglycan-binding protein was purified from the CHAPS extract of brain microsomal fractions using 6B4 proteoglycan-Sepharose. N-terminal sequencing identified this protein as pleiotrophin/heparin-binding growth-associated molecule (HB-GAM). Scatchard analysis of 6B4 proteoglycan- pleiotrophin binding revealed low (Kd = 3 nM) and high (Kd = 0.25 nM) affinity binding sites. Chondroitinase ABC digestion of the proteoglycan decreased the binding affinities to s single value (Kd = 13 nM) without changing the number of binding sites, suggesting the presence of two subpopulations of the proteoglycan with different chondroitin sulfate structures. This was supported by the fact that chondroitin sulfate C but not chondroitin sulfate A inhibited the pleiotrophin-6B4 proteoglycan binding. Anti-6B4 proteoglycan antibody, chondroitin sulfate C and sodium vanadate, a protein tyrosine phosphatase inhibitor, added to the culture medium suppressed pleiotrophin-induced neurite extension and neuronal migration. These results indicated that pleiotrophin is a functional ligand of PTPzeta.
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