Human chondrocyte expression of growth-arrest-specific gene 6 and the tyrosine kinase receptor AXL - Potential role in autocrine signaling in cartilage
Human chondrocyte expression of growth-arrest-specific gene 6 and the tyrosine kinase receptor AXL - Potential role in autocrine signaling in cartilage
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DOI：
10.1002/art.1780400814
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发表时间：
1997-08-01
影响因子：
--
通讯作者：
Wallin, R
中科院分区：
文献类型：
--
作者：
Loeser, RF;Varnum, BC;Wallin, R
目标。确定人关节软骨细胞是否表达axl酪氨酸激酶受体及其配体Gas-6（生长抑制特异性基因6的蛋白产物），并确定Gas-6和axl是否在调节软骨细胞生长中起作用。和survival.Methods。采用免疫组织化学方法原位检测了Gas-6和axl在人关节软骨中的存在，并在体外用原代人和永生化人软骨细胞进行了细胞培养研究。测定了重组Gas-6介导软骨细胞粘附和刺激软骨细胞轴突磷酸化的能力。Gas-6和axl在细胞增殖和存活中的作用也进行了研究。免疫组化染色检测软骨组织中Gas-6和axl的表达。在原代和永生化人软骨细胞培养中也检测到Gas-6和axl信使RNA （mRNA）和蛋白。与含10%血清培养基中培养的细胞相比，无血清培养基中培养的永生化软骨细胞Gas-6 mRNA水平升高，axl表达降低。软骨细胞附着在气-6包覆的塑料上，这种附着被含有轴突胞外结构域的可溶性Ig融合蛋白阻断。重组人Gas-6和来自原代和永生化人软骨细胞培养的无血清条件培养基刺激软骨细胞轴氨酸磷酸化。用重组Gas-6刺激永生化软骨细胞或转染过表达axl的软骨细胞均可观察到有丝分裂效应。在无血清培养基中加入重组Gas-6可提高琼脂糖低密度培养的原代软骨细胞的存活率。这些发现证明软骨中存在一个涉及Gas-6和轴氨酸酪氨酸激酶粘附受体的自分泌信号通路，Gas-6对轴氨酸的刺激可能在软骨细胞生长和存活的控制中起重要作用。
Objective. To determine if human articular chondrocytes express the axl tyrosine kinase receptor and its ligand Gas-6, a protein product of growth-arrest-specific gene 6, and to determine if Gas-6 and axl function in the regulation of chondrocyte growth. and survival.Methods. The presence of Gas-6 and axl was examined in situ in human articular cartilage by immunohistochemistry and in vitro in cell culture studies using primary human chondrocytes and immortalized human chondrocytes. The ability of recombinant Gas-6 to mediate adhesion of chondrocytes and to stimulate chondrocyte axl phosphorylation was determined. Studies of the role of Gas-6 and axl in cell proliferation and survival were also performed.Results. Both Gas-6 and axl were detected in cartilage by immunohistochemical staining. Gas-6 and axl messenger RNA (mRNA) and protein were also detected in cultures of primary and immortalized human chondrocytes. Compared with cells cultured in medium containing 10% serum, Gas-6 mRNA levels were increased in immortalized chondrocytes cultured in serum-free medium, while axl expression decreased. Chondrocytes attached to Gas-6-coated plastic, and the attachment was blocked by a soluble Ig fusion protein containing the axl extracellular domain. Recombinant human Gas-6 and serum-free conditioned medium from primary and immortalized human chondrocyte cultures stimulated chondrocyte axl tyrosine phosphorylation. A mitogenic effect was noted both when immortalized chondrocytes were stimulated with recombinant Gas-6 or when they were made to overexpress axl by transfection, Addition of recombinant Gas-6 to serum-free medium resulted in increased survival of primary chondrocytes cultured at low density in agarose.Conclusion. These findings present evidence for an autocrine signaling pathway in cartilage involving Gas-6 and the axl tyrosine kinase adhesion receptor, Stimulation of axl by Gas-6 may play an important role in the control of chondrocyte growth and survival.