|Budget Amount *help
¥128,960,000 (Direct Cost: ¥99,200,000、Indirect Cost: ¥29,760,000)
Fiscal Year 2013: ¥26,650,000 (Direct Cost: ¥20,500,000、Indirect Cost: ¥6,150,000)
Fiscal Year 2012: ¥26,000,000 (Direct Cost: ¥20,000,000、Indirect Cost: ¥6,000,000)
Fiscal Year 2011: ¥26,520,000 (Direct Cost: ¥20,400,000、Indirect Cost: ¥6,120,000)
Fiscal Year 2010: ¥26,000,000 (Direct Cost: ¥20,000,000、Indirect Cost: ¥6,000,000)
Fiscal Year 2009: ¥23,790,000 (Direct Cost: ¥18,300,000、Indirect Cost: ¥5,490,000)
In mice, two membrane proteins, CD9 and IZUMO1, are required for sperm-egg fusion. Moreover, CD9-containing vesicles, termed egg exosomes, are released from eggs and transfered to the sperm, and then facilitate sperm fusion with the egg. Here we investigated that the egg exosomes play a role in conferring the nature of apoptotic cells on the sperm membrane by transferring inside-out CD9. Our results provide an insight into fertilization, proposing the sperm-egg fusion is controlled by a mechanism shared with phagocytosis of apoptotic cells. Moreover, we dissected IZUMO1 protein to determine the domains that were required for the function of sperm-egg fusion. We found that a fragment of the N terminus (Asp5 to Leu113) interacts with fertilization inhibitory antibodies. It also binds to the egg surface and effectively inhibits fusion in vitro. These findings suggest that the formation of a helical dimer at the N-terminal region of IZUMO1 is required for its function.