Unexpected role of the copper transporter ATP7A in PDGF-induced vascular smooth muscle cell migration.
BACKGROUND
Copper, an essential nutrient, has been implicated in vascular remodeling and atherosclerosis with unknown mechanism. Bioavailability of intracellular copper is regulated not only by the copper importer CTR1 (copper transporter 1) but also by the copper exporter ATP7A (Menkes ATPase), whose function is achieved through copper-dependent translocation from trans-Golgi network (TGN). Platelet-derived growth factor (PDGF) promotes vascular smooth muscle cell (VSMC) migration, a key component of neointimal formation.


OBJECTIVE
To determine the role of copper transporter ATP7A in PDGF-induced VSMC migration.


RESULTS
Depletion of ATP7A inhibited VSMC migration in response to PDGF or wound scratch in a CTR1/copper-dependent manner. PDGF stimulation promoted ATP7A translocation from the TGN to lipid rafts, which localized at the leading edge, where it colocalized with PDGF receptor and Rac1, in migrating VSMCs. Mechanistically, ATP7A small interfering RNA or CTR small interfering RNA prevented PDGF-induced Rac1 translocation to the leading edge, thereby inhibiting lamellipodia formation. In addition, ATP7A depletion prevented a PDGF-induced decrease in copper level and secretory copper enzyme precursor prolysyl oxidase (Pro-LOX) in lipid raft fraction, as well as PDGF-induced increase in LOX activity. In vivo, ATP7A expression was markedly increased and copper accumulation was observed by synchrotron-based x-ray fluorescence microscopy at neointimal VSMCs in wire injury model.


CONCLUSIONS
These findings suggest that ATP7A plays an important role in copper-dependent PDGF-stimulated VSMC migration via recruiting Rac1 to lipid rafts at the leading edge, as well as regulating LOX activity. This may contribute to neointimal formation after vascular injury. Our findings provide insight into ATP7A as a novel therapeutic target for vascular remodeling and atherosclerosis.
Ashino
Takashi
T
Department of Medicine, Section of Cardiology, Center for Cardiovascular Research, University of Illinois at Chicago, Chicago, IL 60612, USA.
Sudhahar
Varadarajan
V
Urao
Norifumi
N
Oshikawa
Jin
J
Chen
Gin-Fu
GF
Wang
Huan
H
Huo
Yuqing
Y
Finney
Lydia
L
Vogt
Stefan
S
McKinney
Ronald D
RD
Maryon
Edward B
EB
Kaplan
Jack H
JH
Ushio-Fukai
Masuko
M
Fukai
Tohru
T
D000251:Adenosine Triphosphatases / Q000502:physiology*; D000818:Animals; D050197:Atherosclerosis / Q000201:enzymology / Q000473:pathology; D027682:Cation Transport Proteins / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D003300:Copper / Q000378:metabolism*; D000073840:Copper-Transporting ATPases; D006801:Humans; D008297:Male; D021962:Membrane Microdomains / Q000201:enzymology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000473:pathology / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000201:enzymology* / Q000473:pathology / Q000502:physiology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
C486201:Atp7a protein, mouse; D027682:Cation Transport Proteins; D010982:Platelet-Derived Growth Factor; D003300:Copper; D000251:Adenosine Triphosphatases; C081184:ATP7A protein, human; C486202:Atp7a protein, rat; D000073840:Copper-Transporting ATPases