臨床検査55巻1号

2011年01月発行

今月の主題 -ミクログロブリン－その多様な病因，病態と検査アプローチ 総論

β₂-ミクログロブリンの近位尿細管における再吸収・代謝機構―エンドサイトーシス受容体メガリンの構造，機能，分子間相互作用

著者： 忰田亮平¹ 斎藤亮彦²

所属機関： ¹新潟大学大学院医歯学総合研究科腎・膠原病内科学分野 ²新潟大学大学院医歯学・機能分子医学講座

ページ範囲：P.37 - P.46

β₂-ミクログロブリンは，糸球体を濾過した後，近位尿細管上皮細胞に発現するエンドサイトーシス受容体メガリンよって再吸収され，代謝・分解される．メガリンは，様々な膜受容体やトランスポーターあるいは細胞内分子と結合・共役しながら，アルブミンを含む多くの低分子量蛋白質の代謝・分解にかかわっている．さらに細胞内のシグナル伝達にも関与すると考えられている．メガリンを介する過剰な，あるいは病的なリガンドの代謝は，近位尿細管上皮細胞の傷害を引き起こす原因となる．メガリンの発現・機能調節は，インスリンやアンジオテンシンIIなどがかかわるが，それは蛋白尿の発症とともに，生体における様々な有用分子の回収の障害に関係している．このようなメガリンの機能を腎疾患の診断や治療に応用しようという研究も進められている．

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