Lens structure in MIP-deficient mice
Lens structure in MIP-deficient mice
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DOI：
10.1002/ar.a.10080
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发表时间：
2003-08-01
期刊：
影响因子：
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通讯作者：
Kuszak, JR
中科院分区：
文献类型：
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作者：
Al-Ghoul, KJ;Kirk, T;Kuszak, JR
在这项研究中，我们使用相关的光、扫描和透射(冷冻蚀刻)电子显微镜来表征正常小鼠的晶状体结构，并将其与缺乏纤维细胞主要内在蛋白(MIP)的小鼠的晶状体结构进行比较。大体上，野生型晶状体是透明的，在所有被检查的年龄都有典型的Y形缝线。这些晶状体具有均匀形状的纤维(横截面为六边形)，排列成有序的同心生长壳和放射状细胞柱。此外，这些纤维具有正常的对端弯曲和沿其长度规则排列的侧向交错。超微结构评价显示，这些纤维的前后端节段在低波幅波状纤维膜上呈方阵列膜特征。这些纤维中约有13%的赤道段或中段被特化为缝隙连接(GJS)。相比之下，杂合子晶状体虽然在出生时最初是透明的，但在3周大时就是半透明的，除了周围透明的区域，在伸长的早期阶段含有纤维。这种透明度的下降与纤维结构的异常有关。具体地说，虽然这些纤维的中段基本正常，但其末端段缺乏正常的对端曲率，比正常大，并具有明显的非六角形形状。结果，这些纤维不能形成典型的Y形缝合。此外，杂合子晶状体的核纤维甚至更大，缺乏任何有序排列的外观。大体上，纯合子晶状体在检查的所有年龄都是不透明的，除了外围透明区域，在伸长的早期阶段含有纤维。纯合子晶状体的所有纤维都缺乏相反的端曲率，因此无法形成任何缝线。此外，这些纤维基本上没有联锁装置，只有7%的中段被专门用作GJS。本研究的结果表明，MIP在建立和维持均匀的纤维结构以及纤维的组织方面起着至关重要的作用，因此对于晶状体的功能是必不可少的。(C)2003年Wiley-Liss，Inc.
In this study we used correlative light, scanning, and transmission (freeze-etch) electron microscopy to characterize lens structure in normal mice and compare it with that in mice deficient in the major intrinsic protein (MIP) of fiber cells. Grossly, wild-type lenses were transparent and had typical Y sutures at all of the ages examined. These lenses had fibers of uniform shape (hexagonal in cross section) arranged in ordered concentric growth shells and radial cell columns. In addition, these fibers had normal opposite end curvature and lateral interdigitations regularly arrayed along their length. Ultrastructural evaluation of these fibers revealed anterior and posterior end segments characterized by square array membrane on low-amplitude wavy fiber membrane. Approximately 13% of the equatorial or mid segments of these same fibers were specialized as gap junctions (GJs). In contrast, heterozygote lenses, while initially transparent at birth, were translucent by 3 weeks of age, except for a peripheral transparent region that contained fibers in the early stages of elongation. This degradation in clarity was correlated with abnormal fiber structure. Specifically, although the mid segment of these fibers was essentially normal, their end segments lacked normal opposite end curvature, were larger than normal, and had a distinct non-hexagonal shape. As a result, these fibers failed to form typical Y sutures. Furthermore, the nuclear fibers of heterozygote lenses were even larger and lacked any semblance of an ordered packing arrangement. Grossly, homozygote lenses were opaque at all ages examined, except for a peripheral transparent region that contained fibers in the early stages of elongation. All fibers from homozygote lenses lacked opposite end curvature, and thus failed to form any sutures. Also, these fibers were essentially devoid of interlocking devices, and only 7% of their mid segment was specialized as GJs. The results of this study suggest that MIP has essential roles in the establishment and maintenance of uniform fiber structure, and the organization of fibers, and as such is essential for lens function. (C) 2003 Wiley-Liss, Inc.