Talin depletion reveals independence of initial cell spreading from integrin activation and traction (Nat Cell Biol, 2008, 10:1062-1068)

報告日期: 2009/12/08
報告時間: 17:10/18:00
報告學生: 陳勝義
講評老師: 呂增宏


Talin depletion reveals independence of initial cell spreading from integrin activation and traction

Xian Zhang. et al. Nat. Cell Biol. 10, 10621068 (2008)


Speaker: Chen, Sheng-Yi

Commentator: Dr. Leu, Tzeng-Horng

Time: 17:00-18:00, Dec. 08, 2009

Place: 602



Cell spreading and adhesion to the extracellular matrix (ECM) are regulated by the interaction between ECM, integrins and the cell cytoskeleton. The actin-binding proteins talin1 and 2 link integrins to the actin cytoskeleton either directly or indirectly by interacting with vinculin and alpha-actinin and that subsequently increase the affinity of integrins for the ECM. Disruption of the talin1 gene in undifferentiated embryonic stem (ES) cells severely reduces cell adhesion and cytoskeleton organization. Thus, the authors wanted to study the role of talins in initial cell responses to ECM signals. The authors report that depletion of talin2 in talin1-null (talin1–/–) cells cause 77 ± 11% of the cells becaming rounded. To determine whether loss of talins would completely block cell spreading, cells were plated on fibronectin-coated coverslips. Initial cell spreading occurred normally suggesting that by integrin–fibronectin interactions does not require talin. Time-lapse microscopy revealed a short duration of cell spreading in talin-deficient cells whose robust early edge extension rounded up in 28 min after initiation of spreading, compared with the control cells.  Binding of the talin head domain modulates the affinity of integrins for ECM3. Although the expression of talin1 head domain restored β1 integrin activation, only the expression of full-length talin1 restored both the ECM–cytoskeleton linkage and normal cytoskeleton organization. The role of FAK-Tyr 397 phosphorylation in cell spreading was also investigated in this study. Together, these data suggest that talin is not required for initial cell spreading but is required for ECM–cytoskeleton linkage and cytoskeleton organization.



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