| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1999: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
We have carried out studies on the molecular mechanism of macrophage recognition of oxidized cells in the following aspects. 1) Elucidation of structure and function of 50 kDa lectin-like protein which we had isolated previously as a candidate for a receptor molecule of macrophage surface, and 2) elucidation of the mechanism of appearance of the carbohydrate ligands for the recognition on the oxidized cells. Furthermore, in the course of the above studies, we have found that this recognition mechanism works not only in the recognition of oxidized cells but also of the cells dying by apotosis. The findings are as follows.
1. A candidate protein for the receptor molecule was cloned from human cell cDNA library by PCR, based on the partial amino acid sequence of isolated p50. Identification of the protein coded by the cloned cDNA as the oxidized-cell recognizing protein is now in progress.
2. Presence of p50 on macrophage surface was confirmed microscopically by immunofluorescence usig the antibody against the partial amino acid sequence of p50. In addition, macrophage recognition of oxidized cells was inhibited by the antibody, comfirming p50 as a receptor for the oxidized cells.
3. It was found that T cells at an early apoptotic stage were recognized by macrophages through the same mechanism, involving sialyl polylactosaminyl chains on the cell surface, as the recognition of oxidized cells. Interestingly, this carbohydrate-dependent recognition mechanism worked earlier than phosphatidylserine-recognizing mechanism.
4. The carbohydrate chains recognized were found to be those of CD43 glycoprotein of the cell membrane. Moreover, CD43 of oxidized cells or early apoptotic cells were found to undergo clustering. This finding substantiated our hypothesis that clustering of membrane glycoproteins of oxidized or apoptotic cells would generate carbohydrate ligands for the cell recognition.
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