|Budget Amount *help
¥17,600,000 (Direct Cost : ¥17,600,000)
Fiscal Year 1993 : ¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 1992 : ¥15,100,000 (Direct Cost : ¥15,100,000)
1. Cell/substratum adhesive structures of Rous sarcoma virus transformed cells : We observed that Rous sarcoma virus transformed-cells developed both podosomes under the center area of ventral plasma membrane and peripheral adhesion along the cell periphery. Podosomes moved actively on a time scale of minutes, while peripheral adhesions scarecely moved. Contractlie proteins (actin, myosin, caldesmon and tropomyosin) were enriched within the podosomes, which may be responsible for the active movement of podosomes. By contrast, the proteins were not acumulated in peripheral adhesions, where integrins, alternatively, were enriched. These findings suggest that the two adhesive structures may participate in different functions when the cells invade into tissues ; firstly, the cells attach stably on the tissue via peripheral adhesions, and secondly, the podosomes invade into the tissue while activly moving and secreting proteases.
2. Target proteins of annexin VI in brain : To elucidate the r
oles of annexin VI, we searched proteins interacting with annexin VI in the rat brains. Annexin VI bound to 15 spieces of proteins in a Ca^<2+> and phospholipid dependent manner. Of these proteins, about 5 proteins were enriched in the cytoskeletal fraction. One of these proteins was identified to be calspectin. Annexin VI bound to calspectin, inhibiting the F-actin crosslinking activity of calspectin. These observations sugget that annexin VI may be involved in many neuronal functions including Ca^<2+>-dependent regulation of the membrane cytoskeleton.
Actin and actin binding proteins, and motile cell/substratum adhesive structures of neural cells : Cultured neurons possess highly motile cell/substratum adhesive structures called growth cones at tips of neurites. Actin filaments, myosin, caldesmon, tropomyosin and gelsolin were enriched within the growth cones, which may be responsible for the active movement and Ca^<2+> sensitivity of growth cones. We found out that cultured astrocytes also developed highly motile adhesive structures along the processes and termed the adhesion ruffling contact. The movement of ruffling contact was similar to that of growth one. The contractile proteins and gelsolin were also accumulated in the adhesions of astrocytes as well as in growth cones and the podosomes. These findings show that the contratile protein and gelsolin may be molecular bases for the active movement of these motile adhesion. Less