Copper transporter ATP7A interacts with IQGAP1, a Rac1 binding scaffolding protein: role in PDGF-induced VSMC migration and vascular remodeling

Abstract

Vascular smooth muscle cell (VSMC) migration contributes to neointimal formation after vascular injury. We previously demonstrated that copper (Cu) transporter ATP7A is involved in platelet-derived growth factor (PDGF)-induced VSMC migration in a Cu- and Rac1-dependent manner. The underlying mechanism is still unknown. Here we show that ATP7A interacts with IQGAP1, a Rac1 and receptor tyrosine kinase binding scaffolding proteins, which mediates PDGF-induced VSMC migration and vascular remodeling. In cultured rat aortic SMCs, PDGF stimulation rapidly promoted ATP7A association with IQGAP1 and Rac1 and their translocation to the lipid rafts and leading edge. Cotransfection assay revealed that ATP7A directly bound to NH2-terminal domain of IQGAP1. Functionally, either ATP7A or IQGAP1 depletion using siRNA significantly inhibited PDGF-induced VSMC migration without additive effects, suggesting that IQGAP1 and ATP7A are in the same axis to promote migration. Furthermore, IQGAP1 siRNA blocked PDGF-induced ATP7A association with Rac1 as well as its translocation to leading edge, while PDGF-induced IQGAP1 translocation was not affected by ATP7A siRNA or Cu chelator. Overexpression of mutant IQGAP1 lacking a Rac1 binding site prevented PDGF-induced translocation of Rac1, but not ATP7A, to the leading edge, thereby inhibiting lamellipodia formation and VSMC migration. In vivo, ATP7A colocalized with IQGAP1 at neointimal VSMCs in a mice wire injury model, while neointimal formation and extracellular matrix deposition induced by vascular injury were inhibited in ATP7A mutant mice with reduced Cu transporter function. In summary, IQGAP1 functions as ATP7A and Rac1 binding scaffolding protein to organize PDGF-dependent ATP7A translocation to the lamellipodial leading edge, thereby promoting VSMC migration and vascular remodeling.

Single-cell tracking demonstrates copper chaperone Atox1 to be required for breast cancer cell migration

“…ATP7A Silencing Reduces Single Breast Cancer Cell Migration Velocity and Directionality. Since recent studies showed ATP7A to be important for metastasis in a different breast cancer system (20) and for stimulated migration of vascular smooth-muscle cells (38), we decided to test if ATP7A is also involved here, with Atox1, to promote MDA-231 breast cancer cell migration. To test involvement of ATP7A, we assessed cell migration in control versus ATP7A-silenced cells with the same methodology as for Atox1.…”

“…Earlier work showed Atox1 to be important for PDGF-stimulated smooth-muscle cell migration, and it was suggested that in these cells Atox1 mediates migration via interactions with ATP7A and Rac1 (34). This work was followed by another study, using the same smooth-muscle cells, where it was shown that cell migration is promoted by ATP7A interactions with IQGAP1 (IQ motif containing GTPase activating protein 1) and Rac1, whereby all proteins translocate to the leading edge of the cells (38). IQGAP1 is a Rac1-binding scaffolding protein that plays a central role in the assembly of signaling complexes that regulate cellular motility, morphogenesis, and cell adhesion (43).…”

The Multifaceted Roles of Copper in Cancer: A Trace Metal Element with Dysregulated Metabolism, but Also a Target or a Bullet for Therapy

“…Concerning the ATP7A protein, it is also deregulated in many cancers, such as in pancreatic cancer, where ATP7A is upregulated compared to that in chronic pancreatitis [60]. The ATP7A protein plays an important role in the formation of metastases in breast cancer and induces the migration of vascular smooth muscle cells [130]. In addition, high levels of ATP7A expression in primary tumors are associated with reduced survival according to publicly available databases [131].…”

The Multifaceted Roles of Copper in Cancer: a Trace Metal Element with Dysregulated Metabolism, but also a Target or a Bullet for Therapy

“…ATP7A protein is also deregulated in many cancers, such as in pancreatic cancer where ATP7A is upregulated compared to chronic pancreatitis [52]. The ATP7A protein plays an important role in the formation of metastases in breast cancer and induces the migration of vascular smooth muscle cells [53]. In addition, high levels of ATP7A expression in primary tumors are associated with reduced survival according to publicly available databases [54].…”