Hyaluronan induces vascular smooth muscle cell migration through RHAMM-mediated PI3K-dependent Rac activation.
OBJECTIVE
Hyaluronan (HA) is an important constituent of the extracellular matrix and is known to regulate cellular events through binding to CD44 and the receptor for HA-mediated motility (RHAMM). Here we investigated the role of these receptors and the signaling pathways involved in HA-mediated effects in arterial smooth muscle cells (ASMC).


METHODS
Effects of high-molecular weight HA (1 to 5 mg/ml) were analyzed in cultured ASMC from rat aorta.


RESULTS
HA promoted actin stress fiber and lamellipodia formation and dose-dependently induced ASMC migration without effect on proliferation. Pull-down assay of Rho protein activity indicated that HA activated RhoA and Rac. HA-induced ASMC migration was not affected by the RhoA inhibitor Tat-C3 (10 microg/ml), the Rho kinase inhibitor Y-27632 (10 microM) and blocking anti-CD44 antibody ,but was reduced by the non-selective Rho protein inhibitor simvastatin (10 microM), the Rac inhibitor LT-toxin (1 mug/ml), small interfering RNA (siRNA) targeting Rac and the phosphatidyl inositol 3-kinase (PI3K) inhibitor LY294002 (25 microM), which also blocked HA-induced Rac activation. CD44 knockdown by siRNA inhibited HA-mediated RhoA activation without effect on ASMC migration. In contrast, siRNA targeting RHAMM inhibited both HA-induced migration and Rac activation.


CONCLUSIONS
High-molecular weight HA independently activates RhoA and Rac through CD44 and RHAMM, respectively. HA-induced migration depends exclusively on RHAMM-mediated PI3K-dependent Rac activation.
Gouëffic
Yann
Y
Inserm, Université de Nantes, U533, l'institut du thorax, Nantes, F-44000, France. yann.goueffic@chu-nantes.fr
Guilluy
Christophe
C
Guérin
Patrice
P
Patra
Philippe
P
Pacaud
Pierre
P
Loirand
Gervaise
G
D000199:Actins / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001011:Aorta; D001427:Bacterial Toxins / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D003176:Complement C3 / Q000235:genetics; D003599:Cytoskeleton / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004768:Enterotoxins / Q000494:pharmacology; D029968:Escherichia coli Proteins / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D015756:Genes, tat; D018960:Hyaluronan Receptors / Q000276:immunology / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors; D009025:Morpholines / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D015398:Signal Transduction; D019821:Simvastatin / Q000494:pharmacology; D013268:Stimulation, Chemical; D020744:rac GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism
D000199:Actins; D000577:Amides; D000911:Antibodies, Monoclonal; D001427:Bacterial Toxins; D002867:Chromones; D003176:Complement C3; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D016326:Extracellular Matrix Proteins; D018960:Hyaluronan Receptors; D006820:Hyaluronic Acid; D047908:Intracellular Signaling Peptides and Proteins; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011725:Pyridines; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D019821:Simvastatin; D020744:rac GTP-Binding Proteins; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; C098946:hyaluronan-mediated motility receptor; C108830:Y 27632; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C027538:heat-labile enterotoxin, E coli