1998 Fiscal Year Final Research Report Summary
STUDY ON ROLE OF MICROTUBLE-BINDING AND RHO-ACTIVATING FACTORS IN CYTOKINESIS
| Project/Area Number |
09680694
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Cell biology
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| Research Institution | KOBE UNIVERSITY |
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Principal Investigator |
ENOMOTO Taira KOBE UNIVERSITY,SCHOOL OF MEDICINE,ASSOCIATE PROFESSOR, 医学部, 助教授 (00127622)
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| Project Period (FY) |
1997 – 1998
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| Keywords | MICROTUBLE / ACTIN RING / RHO G-PROTEIN / TUBULIN / CYTOKINESIS / COLCEMID |
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| Research Abstract |
To obtain insight into the molecular dynamics and involvement of microtubles and the related signal molecules in the regulation of cell locomotion, we studied the influence of microtuble disruption on actin stress fibers and focal adhesion assembly in addition to cell morphology. We found that all microtuble- disrupting drugs including colcemid and vinblastine rapidly and rever sibly induce the for mation of actin stress fibers and focal adnesions containing vinculin, accompanied by activated cell molility ih ser um- starved Balb/c3T3 cells. In contrast, taxol, a microtuble- stabilizing drug, completely inhibited these effects of the microtuble- disrupting drugs. A microinjection of C3ADP-ribosyltransfer ase, a specific inhibitor of rho GTP ase, blocked the stress fiber and focal adnesion assembly induced by the microtuble disruption. These results suggested that microtubles contain signal molecules that regulate the for mation of stress fibers and focal adnesions by activating the rho signal cascade. We postulate that microtuble - releasing and stress fiber- inducing factors link the intrinsically variable and irregul ar actin filament dynamics to coor dinated and directional locomotion in the process of cell movement. To identify the factor, we further analyzed the activity of rho activation in cytoslic and membrane fractions. We found that microtuble- binding protein fractions had the activity for rhoGDI inhibition, indicating that microtuble fractions contain rhoGDI inhibitor. Further investigations showed that tubulin proteins, main component of microtuble fraction, directly bind to and inhibit the activity of rhoGDI.These results clearly show that tubulin proteins inhibit rhoGDI, resulting inreleasing of rho G-protein from RhoGDI and eventialy activating rho G- protein. The activated rho promotes polymerization of actin proteins which require cytokinesis of mammalian cells.
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