Gouëffic Yann, Guilluy Christophe, Guérin Patrice, Patra Philippe, Pacaud Pierre, Loirand Gervaise
Inserm, Université de Nantes, U533, l'institut du thorax, Nantes, F-44000, France.
Cardiovasc Res. 2006 Nov 1;72(2):339-48. doi: 10.1016/j.cardiores.2006.07.017. Epub 2006 Jul 29.
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).
Effects of high-molecular weight HA (1 to 5 mg/ml) were analyzed in cultured ASMC from rat aorta.
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.
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.
透明质酸（HA）是细胞外基质的重要组成部分，已知其通过与CD44和透明质酸介导的运动受体（RHAMM）结合来调节细胞活动。在此，我们研究了这些受体的作用以及参与HA对动脉平滑肌细胞（ASMC）作用的信号通路。
分析了高分子量HA（1至5mg/ml）对大鼠主动脉培养的ASMC的影响。
HA促进肌动蛋白应激纤维和片状伪足形成，并剂量依赖性地诱导ASMC迁移，而对增殖无影响。Rho蛋白活性的下拉分析表明，HA激活了RhoA和Rac。HA诱导的ASMC迁移不受RhoA抑制剂Tat-C3（10μg/ml）、Rho激酶抑制剂Y-27632（10μM）和抗CD44阻断抗体的影响，但被非选择性Rho蛋白抑制剂辛伐他汀（10μM）、Rac抑制剂LT-毒素（1μg/ml）、靶向Rac的小干扰RNA（siRNA）和磷脂酰肌醇3-激酶（PI3K）抑制剂LY294002（25μM）所抑制，后者也阻断了HA诱导的Rac激活。通过siRNA敲低CD44可抑制HA介导的RhoA激活，但对ASMC迁移无影响。相反，靶向RHAMM的siRNA抑制了HA诱导的迁移和Rac激活。
高分子量HA分别通过CD44和RHAMM独立激活RhoA和Rac。HA诱导的迁移仅依赖于RHAMM介导的PI3K依赖性Rac激活。
