Lamellipodial tension, not integrin/ligand binding, is the crucial factor to realise integrin activation and cell migration

详细信息    查看全文

• 作者：Carsten Schulte^a ; ^c ; ^{carsten.schulte@unimi.it" class="auth_mail" title="E-mail the corresponding author} ; Gian Maria Sarra Ferraris^a ; Amanda Oldani^b ; Massimiliano Galluzzi^c ; Alessandro Podestà ; ^c ; Luca Puricelli^c ; Valentina de Lorenzi^a ; Cristina Lenardi^c ; Paolo Milani^c ; Nicolai Sidenius^a
• 关键词：ABS ; actin-binding site ; ΔABS ; actin-binding site deletion ; ECM ; extracellular matrix ; FA(s) ; focal adhesion(s) ; f-Actin ; filamentous actin ; FC(s) ; focal complex(es) ; FERM ; 4.1 protein ; ezrin ; radixin ; moesin ; FN ; fibronectin ; (k)Pa ; (kilo)Pascal ; mAb ; monoclonal antibody ; MC ; molecular clutch ; MCBD ; methyl-β-cyclodextrin ; MIDAS ; metal ion-dependent adhesion sites ; pN ; pico Newton ; TLN ; talin ; uPA ; urokinase plasminogen activator ; uPAR ; urokinase plasminogen activator receptor ; VN ; vitronectin
• 刊名：European Journal of Cell Biology
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：95
• 期：1
• 页码：1-14
• 全文大小：4169 K

文摘

The molecular clutch (MC) model proposes that actomyosin-driven force transmission permits integrin-dependent cell migration. To investigate the MC, we introduced diverse talin (TLN) and integrin variants into Flp-In™ T-Rex™ HEK293 cells stably expressing uPAR. Vitronectin variants served as substrate providing uPAR-mediated cell adhesion and optionally integrin binding. This particular system allowed us to selectively analyse key MC proteins and interactions, effectively from the extracellular matrix substrate to intracellular f-actin, and to therewith study mechanobiological aspects of MC engagement also uncoupled from integrin/ligand binding. With this experimental approach, we found that for the initial PIP₂-dependent membrane/TLN/f-actin linkage and persistent lamellipodia formation the C-terminal TLN actin binding site (ABS) is dispensable. The establishment of an adequate MC-mediated lamellipodial tension instead depends predominantly on the coupling of this C-terminal TLN ABS to the actomyosin-driven retrograde actin flow force. This lamellipodial tension is crucial for full integrin activation eventually determining integrin-dependent cell migration. In the integrin/ligand-independent condition the frictional membrane resistance participates to these processes. Integrin/ligand binding can also contribute but is not necessarily required.