The Motor Protein Myosin-X Transports VE-Cadherin along Filopodia To Allow the Formation of Early Endothelial Cell-Cell Contacts

Abstract

Vascular endothelium (VE), the monolayer of endothelial cells that lines the vascular tree, undergoes damage at the basis of some vascular diseases. Its integrity is maintained by VE-cadherin, an adhesive receptor localized at cell-cell junctions. Here, we show that VE-cadherin is also located at the tip and along filopodia in sparse or subconfluent endothelial cells. We observed that VE-cadherin navigates along intrafilopodial actin filaments. We found that the actin motor protein myosin-X is colocalized and moves synchronously with filopodial VE-cadherin. Immunoprecipitation and pulldown assays confirmed that myosin-X is directly associated with the VE-cadherin complex. Furthermore, expression of a dominant-negative mutant of myosin-X revealed that myosin-X is required for VE-cadherin export to cell edges and filopodia. These features indicate that myosin-X establishes a link between the actin cytoskeleton and VE-cadherin, thereby allowing VEcadherin transportation along intrafilopodial actin cables. In conclusion, we propose that VE-cadherin trafficking along filopodia using myosin-X motor protein is a prerequisite for cell-cell junction formation. This mechanism may have functional consequences for endothelium repair in pathological settings.

Myo10 is a key regulator of TNT formation in neuronal cells

“…In addition, in subconfluent human umbilical vein endothelial cells (HUVECs) (Almagro et al, 2010), Myo10 has been shown to mediate the transport of vascular endothelial-cadherins (VE-Cad) within filopodia to the cell edges that are necessary for the correct formation of cell-cell junctions. These independent observations led us to propose that N-cadherin is a downstream binding partner of Myo10.…”

“…While the FERM domain is composed of three subdomains (F1, F2 and F3 lobes), only the F2 and F3 lobes are required for Myo10 binding to integrins (Zhang et al, 2004). This domain is also important for binding to netrin receptors (Zhu et al, 2007) and to VECadherins in endothelial cells (Almagro et al, 2010), suggesting that it is a general region for cargo binding. This hypothesis was further supported by recent structural studies (Wei et al, 2011, Hirano et al, 2011, showing that the netrin receptor DCC, integrins and microtubules bind to the same region (Hirano et al, 2011).…”

Myosin X and its motorless isoform differentially modulate dendritic spine development by regulating trafficking and retention of vasodilator-stimulated phosphoprotein

“…To date, only a few cargoes have been identified for Myo10 (Almagro et al, 2010;Pi et al, 2007;Tokuo and Ikebe, 2004;Zhang et al, 2004;Zhu et al, 2007). Among the identified cargoes, VASP was an attractive candidate for mediating the Myo10-promoted phenotypes on filopodia and spines because VASP family proteins regulate filopodia formation and spinogenesis by remodeling the underlying actin cytoskeleton (Lin et al, 2010;Lin et al, 2007).…”

Listen to your gut: Using adhesion to shape the surface of functionally diverse epithelia

“…14 Other actin-based protrusions that accumulate specific factors at their tips have invoked myosin motors to drive transport to and enrichment at the barbed-ends of supporting actin bundles (e.g., myosin-10 in filopodia). [16][17][18][19][20][21] A myosin motor might play a similar role in microvilli as the cytoplasmic domains of CDHR2 and CDHR5 interact with the tandem MyTH4/FERM (MF) domain motor, myosin-7b (MYO7B). 14 CDHR2, CDHR5, and MYO7B also interact with the PDZ domain scaffolding protein, USH1C, which likely enhances the lifetime of interactions between the motor and its cargo (i.e., the protocadherins).…”