Chondroitin 6-sulfotransferase (C6ST) catalyzes the transfer of sulfate to position 6 of the N-acetylgalactosamine residue of chondroitin. To obtain direct evidence regarding the function of C6ST and its product, chondroitin 6-sulfate, in vivo, we isolated the mouse C6ST gene (C6st) and generated mice deficient in this gene (C6st ؊/؊ ) by embryonic stem cell technology. C6st؊/؊ mice were born at approximately the expected frequency and were viable through adulthood. In the spleen of C6st ؊/؊ mice, the level of chondroitin 6-sulfate became almost undetectable. Analyses of these knockout mice provided insights into the biosynthesis of oversulfated chondroitin sulfates in mice; chondroitin sulfate D in the brain of null mice and the cartilage and telencephalon of null embryos disappeared, whereas the chondroitin sulfate E level in the spleen and brain of the null mice was unchanged. Despite the disappearance of chondroitin sulfate D structure, brain development was normal in the C6st ؊/؊ mice. Further analysis revealed that the number of CD62L ؉ CD44 low T lymphocytes corresponding to naive T lymphocytes in the spleen of 5-6-week-old C6st ؊/؊ mice was significantly decreased, whereas those in other secondary lymphoid organs were unchanged. This finding suggested that chondroitin 6-sulfate plays a role in the maintenance of naive T lymphocytes in the spleen of young mice.

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凝固系は，外因系(extrinsic pathway)と内因 系(intrinsic pathway)に大別される(1) ．外 因系は組織因子(TF)が血流に露出することで 開始される．TF は血中の VII 因子(FVII)また は活性型 FVII(FVIIa)と結合し，FVIIa-TF 複 合体が IX 因子(FIX)および X 因子(FX)を 活性化する． 一方，内因系は，陰性電荷物質に結合した XII 因子(FXII)の活性化によって惹起される．活 性 型 FXII(FXIIa) は， 高 分 子 キ ニ ノ ー ゲ ン (HMWK)を介して陰性電荷上に濃縮された XI 因子(FXI)を活性化する．これらの陰性電荷表 ＊ 1 摂南大学理工学部生命科学科〔〒 572-8508 大阪府寝屋川市池田中町 17-8〕