Functions of lumican and fibromodulin: Lessons from knockout mice
Functions of lumican and fibromodulin: Lessons from knockout mice
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DOI：
10.1023/a:1025348417078
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发表时间：
2002-05-01
影响因子：
3
通讯作者：
Chakravarti, S
中科院分区：
文献类型：
--
作者：
Chakravarti, S
Lumican和纤维调节蛋白是胶原结合的富含亮氨酸的蛋白聚糖，广泛分布于间质结缔组织中。lumican-null （Lum(-/-)）、Fibromodulin-null （Fmod(-/-)）和compound double-null （Lum(-/-)）小鼠的表型鉴定了这两种蛋白多糖在调节细胞外基质和细胞行为方面具有重叠和独特作用的广泛组织。缺乏荧光蛋白的小鼠角膜透明度和皮肤脆弱性降低。Lum(-/-)Fmod（-/-）小鼠比野生型小鼠更小，表现出步态异常、关节松弛和年龄依赖性骨关节炎。膝关节髌骨错位、严重的膝关节畸形和极度的肌腱无力是导致关节松弛的可能原因。纤维调节素缺乏单独导致Lum(+/+)Fmod（-/-）小鼠肌腱僵硬度显著降低，并以lumican基因剂量依赖性的方式进一步降低僵硬度。超微结构上，Lum（-/-）角膜、皮肤和肌腱胶原纤维轮廓不规则，纤维直径增大。Fmod（-/-）肌腱含有不规则轮廓的胶原原纤维，小直径原纤维的频率增加。Lum(-/-)Fmod（-/-）的肌腱具有异常高的小直径和大直径原纤维频率，表明胶原原纤维的形成和成熟失调。在肌腱等两种蛋白聚糖均存在的组织中，在胶原纤维形成的早期可能需要纤维调节蛋白来稳定小直径的原纤维中间体，而在后期可能需要lumican，主要是为了限制原纤维的侧向生长。
Lumican and fibromodulin are collagen-binding leucine-rich proteoglycans widely distributed in interstitial connective tissues. The phenotypes of lumican-null (Lum(-/-)), Fibromodulin-null (Fmod(-/-)) and compound double-null (Lum(-/-)Fmod(-/-)) mice identify a broad range of tissues where these two proteoglycans have overlapping and unique roles in modulating the extracellular matrix and cellular behavior. The lumican-deficient mice have reduced corneal transparency and skin fragility. The Lum(-/-)Fmod(-/-) mice are smaller than their wildtype littermates, display gait abnormality, joint laxity and age-dependent osteoarthritis. Misaligned knee patella, severe knee dysmorphogenesis and extreme tendon weakness are the likely cause for joint-laxity. Fibromodulin deficiency alone leads to significant reduction in tendon stiffness in the Lum(+/+)Fmod(-/-) mice, with further loss in stiffness in a lumican gene dose-dependent way. At the level of ultrastructure, the Lum(-/-) cornea, skin and tendon show irregular collagen fibril contours and increased fibril diameter. The Fmod(-/-) tendon contains irregular contoured collagen fibrils, with increased frequency of small diameter fibrils. The tendons of Lum(-/-)Fmod(-/-) have an abnormally high frequency of small and large diameter fibrils indicating a deregulation of collagen fibril formation and maturation. In tissues like the tendon, where both proteoglycans are present, fibromodulin may be required early in collagen fibrillogenesis to stabilize small-diameter fibril-intermediates and lumican may be needed at a later stage, primarily to limit lateral growth of fibrils.