| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2004: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Ectodomain shedding is an irreversible posttranslational modification that releases the extracellular domain of membrane-anchored protein through proteolysis. Abroad spectrum of membrane protein is susceptible to ectodomain shedding, and the process is strictly regulated. Several lines of evidence showed that metalloproteinases, especially those belonging to a disintegrin and metalloproteinase (ADAM) family are directly involved in this process as sheddases. The mechanism of induced shedding, however, remained unclear. Here we show that nardilysin (N-arginine dibasic convertase ; NRDc), a metalloendopeptidase of M16 family, enhances ectodomain shedding of EGF receptor ligands and TNF-alpha When expressed in cells, NRDc enhanced HB-EGF and TNF-α shedding coordinately with TNF-α converting enzyme (TACE, ADAM17). NRDc is hound to TACE and the cnmplex formation in cells is increased by phorhol esters, general activators of ectodomain shedding. Furthermere, NRDc enhanced TACE-induced substrate cleavage in a peptide cleavage assay, indicating that the interaction with NRDc potentiates the catalytic activity of TACE. Importantly, reduction of NEDc expression by RNA interference was accompanied by a decrease in ectodomain shedding. NRDc also induced HB-EGF shedding even in TACE deficient cells and shedding induced by ADAM9 was also enhanced by NRDc. These results indicate the essential role of NEDc in ectodomain shedding and uncover a novel molecular mechanism of how ectodomain shedding is regulated by modulation of sheddase activity.
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