Rab-coupling protein coordinates recycling of α5β1 integrin and EGFR1 to promote cell migration in 3D microenvironments

Abstract

Here we show that blocking the adhesive function of αvβ3 integrin with soluble RGD ligands, such as osteopontin or cilengitide, promoted association of Rab-coupling protein (RCP) with α5β1 integrin and drove RCP-dependent recycling of α5β1 to the plasma membrane and its mobilization to dynamic ruffling protrusions at the cell front. These RCP-driven changes in α5β1 trafficking led to acquisition of rapid/random movement on two-dimensional substrates and to a marked increase in fibronectin-dependent migration of tumor cells into three-dimensional matrices. Recycling of α5β1 integrin did not affect its regulation or ability to form adhesive bonds with substrate fibronectin. Instead, α5β1 controlled the association of EGFR1 with RCP to promote the coordinate recycling of these two receptors. This modified signaling downstream of EGFR1 to increase its autophosphorylation and activation of the proinvasive kinase PKB/Akt. We conclude that RCP provides a scaffold that promotes the physical association and coordinate trafficking of α5β1 and EGFR1 and that this drives migration of tumor cells into three-dimensional matrices.

On the move: endocytic trafficking in cell migration

“…The effect of annexin A2 on EGFR endocytosis is linked to activation of the actin-severing protein cofilin establishing annexin A2 as a mediator of EGFR endocytic trafficking and signaling in breast cancer cells via regulation of cofilin activation [40]. Furthermore, the Rab11 effector Rab-coupling protein (RCP) has pro-invasive effects by forming a complex with the integrin a5b1 and EGFR1 and by coordinating their recycling [41]. EGFR-dependent signaling likely occurs partly from the plasma membrane, leading to the activation of PKB/Akt via phosphoinositide-3-kinase (PI3K), and partly from late endosomal compartments, resulting in the activation of the Ras-MEK-ERK axis (see references in [41]).…”

“…Furthermore, the Rab11 effector Rab-coupling protein (RCP) has pro-invasive effects by forming a complex with the integrin a5b1 and EGFR1 and by coordinating their recycling [41]. EGFR-dependent signaling likely occurs partly from the plasma membrane, leading to the activation of PKB/Akt via phosphoinositide-3-kinase (PI3K), and partly from late endosomal compartments, resulting in the activation of the Ras-MEK-ERK axis (see references in [41]). RCP-dependent recycling might keep EGFR from efficiently reaching late endosomes thereby promoting pro-invasive PKB/Akt signaling [41].…”

“…EGFR-dependent signaling likely occurs partly from the plasma membrane, leading to the activation of PKB/Akt via phosphoinositide-3-kinase (PI3K), and partly from late endosomal compartments, resulting in the activation of the Ras-MEK-ERK axis (see references in [41]). RCP-dependent recycling might keep EGFR from efficiently reaching late endosomes thereby promoting pro-invasive PKB/Akt signaling [41]. These examples illustrate vividly the crucial role of endocytic pathways for correctly localizing growth factor receptors to enable directed migration as well as for limiting or enhancing depending on cellular context potentially oncogenic growth factor receptor signaling.…”

“…The Rab4-dependent recycling of avb3 in fibroblasts and the activity of this integrin for instance suppresses the recycling of a5b1 thereby coordinating their activities and promoting directionally persistent migration [70]. Blocking avb3 on the other hand promotes the association of RCP with a5b1 and its RCP-dependent recycling [41] as well as random movement. As mentioned earlier, RCP also coordinates trafficking of a5b1 integrin and EGFR1 which leads to increased activation of the proinvasive PKB/Akt kinase downstream of EGFR1.…”

Rabs and cancer cell motility

“…In a more recent study, the same authors [Caswell et al, 2008] showed that an effector of the Rab family proteins, Rab11 family interacting protein 1 (Rab11-FIP1), or Rab-coupling protein (RCP), may be another mediator of Rab25's effect on a5b1-integrin traffic and cell migration. Blocking of avb3-mediated cell adhesion with soluble ligands (such as osteopontin or cilengtide) promoted association of RCP with a5b1-integrin, and the latter's recycling to the plasma membrane as well as its mobilization to dynamic protrusions at the cell front.…”