Dynamic and coordinated single‐molecular interactions at TM4SF5‐enriched microdomains guide invasive behaviors in 2‐ and 3‐dimensional environments

Abstract

Membrane proteins sense extracellular cues and transduce intracellular signaling to coordinate directionality and speed during cellular migration. They are often localized to specific regions, as with lipid rafts or tetraspanin-enriched microdomains; however, the dynamic interactions of tetraspanins with diverse receptors within tetraspanin-enriched microdomains on cellular surfaces remain largely unexplored. Here, we investigated effects of tetraspan(in) TM4SF5 (transmembrane 4 L6 family member 5)-enriched microdomains (TERMs) on the directionality of cell migration. Physical association of TM4SF5 with epidermal growth factor receptor (EGFR) and integrin α5 was visualized by live fluorescence cross-correlation spectroscopy and higher-resolution microscopy at the leading edge of migratory cells, presumably forming TM4SF5-enriched microdomains. Whereas TM4SF5 and EGFR colocalized at the migrating leading region more than at the rear, TM4SF5 and integrin α5 colocalized evenly throughout cells. Cholesterol depletion and disruption in TM4SF5 post-translational modifications, including -glycosylation and palmitoylation, altered TM4SF5 interactions and cellular localization, which led to less cellular migration speed and directionality in 2- or 3-dimensional conditions. TM4SF5 controlled directional cell migration and invasion, and importantly, these TM4SF5 functions were dependent on cholesterol, TM4SF5 post-translational modifications, and EGFR and integrin α5 activity. Altogether, we showed that TM4SF5 dynamically interacted with EGFR and integrin α5 in migratory cells to control directionality and invasion.-Kim, H.-J., Kwon, S., Nam, S. H., Jung, J. W., Kang, M., Ryu, J., Kim, J. E., Cheong, J.-G., Cho, C. Y., Kim, S., Song, D.-G., Kim, Y.-N., Kim, T. Y., Jung, M.-K., Lee, K.-M., Pack, C.-G., Lee, J. W. Dynamic and coordinated single-molecular interactions at TM4SF5-enriched microdomains guide invasive behaviors in 2- and 3-dimensional environments.

TM4SF5-Mediated Roles in the Development of Fibrotic Phenotypes

“…Recently, we have shown that TM4SF5 forms a protein complex with EGFR and integrin α 5 at the leading membrane edges [6]; dynamic intra-TERM protein associations and translocations during cell migration depend on interactions mong TM4SF5, EGFR, and integrin α 5 at the leading membrane edges of migratory cells to steer migration. These interactions transduce differential synergistic signals in 2-dimensional (2D) and 3-dimensional (3D) culture systems and determine the directional migration.…”

“…Overexpression of promigratory TM4SF5 results in an internalization of CD63 to late lysosomal membranes and prevents the inhibitory effect of CD63 on migration by presumably removing it from the cell surface [9]. Therefore, TM4SF5 expression can modulate localizations of other membrane receptors like CD63 [9], EGFR, or integrin α 5 [6], although its effects on CD44 localization have not been examined. Finally, the interaction among TM4SF5, integrin α 2 [10], and α 5 can modulate cell migration, invasion, and vascular endothelial growth factor (VEGF) expression.…”

“…Although TM4SF5 binds to many different membrane receptors including CD151, growth factor receptors, and integrins [6], TM4SF5 itself can trigger intracellular focal adhesion kinase (FAK) [12] and c-Src-dependent signaling [13]. Direct interaction of the intracellular loop (ICL) or the cytosolic C-terminal tail of TM4SF5 with FAK or c-Src modulates directional migration and invasion, respectively.…”

“…Cysteines proximal to transmembrane domains are involved in palmitoylation that is critical for the association of TM4SF5 with tetraspanins and other receptors [6]. Meanwhile, TM4SF1 and TM4SF4, which are also transmembrane 4 L six family members, differ from TM4SF5 in the ability to activate FAK and/or c-Src to regulate migration [17].…”

“…T 5 ERMs can have many different components, and various protein-protein interactions among diverse membrane proteins and receptors can occur [6]. Formation of protein complexes among TM4SF5, EGFR, and integrin α 5 leads to differentially coordinated signaling activities depending on the PTMs of TM4SF5, which are discussed above.…”