A COMPARATIVE BIOCHEMICAL AND ULTRASTRUCTURAL-STUDY OF PROTEOGLYCAN COLLAGEN INTERACTIONS IN CORNEAL STROMA - FUNCTIONAL AND METABOLIC IMPLICATIONS
A COMPARATIVE BIOCHEMICAL AND ULTRASTRUCTURAL-STUDY OF PROTEOGLYCAN COLLAGEN INTERACTIONS IN CORNEAL STROMA - FUNCTIONAL AND METABOLIC IMPLICATIONS
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DOI：
10.1042/bj2700491
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发表时间：
1990-09-01
影响因子：
4.1
通讯作者：
BOSWORTH, TR
中科院分区：
文献类型：
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作者：
SCOTT, JE;BOSWORTH, TR
对小鼠、大鼠、豚鼠、兔、羊、猫、狗、猪和牛的角膜进行了水、羟脯氨酸、核酸、总硫酸多阴离子、硫酸软骨素/硫酸皮肤素和硫酸角蛋白的定量分析，每种动物都有几个样本或组织池。类似地，对8个角膜池中的雪貂角膜进行了水和羟脯氨酸的分析。用醋酸纤维素膜电泳法对青蛙(38只)和雪貂(8只)的角膜和人角膜的单一样本进行了硫酸角蛋白和硫酸软骨素/硫酸皮肤素的定性检测。对9种动物(小鼠、青蛙、大鼠、豚鼠、兔、羊、猫、猪和牛)和6种动物(小鼠、青蛙、大鼠、豚鼠、兔和牛)进行了光镜和电子显微镜观察，并用阿尔新蓝或铜蓝对蛋白多糖进行了临界电解质浓度(CEC)染色。水(湿重的百分比)、羟脯氨酸(毫克/克干重)而硫酸软骨素(羟脯氨酸的毫克/克)的含量在整个物种中几乎是恒定的，除了小鼠。随着角膜厚度的增加，硫酸角质形成蛋白的含量(mg/g羟脯氨酸)增加，而硫酸皮肤素的含量减少。小鼠和角膜中没有硫酸角蛋白的过硫化结构域，随着角膜厚度的增加，硫酸角蛋白占总角蛋白的比例增加。硫酸皮肤素的硫化基本完成(即每个二糖单位有一个硫酸盐基团)。硫酸软骨素/硫酸皮肤素蛋白多糖存在于所有物种胶原纤维的d带，且呈正交状排列，出现频率较高，偶尔出现在e带。在所研究的所有物种的a和c带中都存在硫酸角蛋白多糖，但在较厚的角膜中出现的频率要高得多，因为那里的硫酸角蛋白含量很高。Alcian Blue CEC染色显示，与生化分析一致，厚角膜(如牛的角膜)中硫酸角蛋白的硫酸盐含量远高于薄角膜(如小鼠的角膜)。我们认为，纤维间体积的恒定是通过纤维间多阴离子的膨胀和渗透压来调节的，通过调节两个独立的蛋白多糖基团中的硫化程度，实现与完全硫化的硫酸软骨素/皮肤素硫酸盐类似的总多阴离子的“平均硫化”。这两种蛋白多糖的合成平衡可能取决于对无血管角膜的氧气供应。氧气供应也可能决定硫酸软骨素转化为硫酸皮肤素的过程。
Corneas of mouse, rat, guinea pig, rabbit, sheep, cat, dog, pig and cow were quantitatively analysed for water, hydroxyproline, nucleic acid, total sulphated polyanion, chondroitin sulphate/dermatan sulphate and keratan sulphate, several samples or pools of tissues from each species being used. Ferret cornea was similarly analysed for water and hydroxyproline on one pool of eight corneas. Pooled frog (38) and ferret (eight) corneas and a single sample of human cornea were qualitatively examined for keratan sulphate and chondroitin sulphate/dermatan sulphate by electrophoresis on cellulose acetate membranes. Nine species (mouse, frog, rat, guinea pig, rabbit, sheep, cat, pig and cow) were examined by light microscopy and six (mouse, frog, rat, guinea pig, rabbit and cow) by electron microscopy, with the use of Alcian Blue or Cupromeronic Blue in critical-electrolyte-concentration (CEC) methods to stain proteoglycans. Water (% of wet weight), hydroxyproline (mg/g dry wt.) and chondroitin sulphate (mg/g of hydroxyproline) contents were approximately constant across the species, except for mouse. Keratan sulphate contents (mg/g of hydroxyproline) increased with corneal thickness, whereas dermatan sulphate contents decreased. The oversulphated domain of keratan sulphate was absent from mouse and from corneas, increasing as percentage of total keratan with increasing corneal thickness. Sulphation of dermatan sulphate was essentially complete (i.e. one sulphate group per disaccharide unit). Chondroitin sulphate/dermatan sulphate proteoglycans were present at the d bands of the collagen fibrils of all species examined, orthogonally arrayed, with high frequency, and ocassionally at the e bands. Keratan sulphate proteoglycans were present at the a and c bands of all species examined, but with far higher frequency in the thicker corneas, where keratan sulphate contents were high. Alcian Blue CEC staining showed much higher sulphation of keratan sulphate in thick corneas, e.g., that of cow, than in thin corneas, e.g., that of mouse, in keeping with biochemical analyses. It is suggested that the constancy of interfibrillar volumes is regulated via the swelling and osmotic pressure of the interfibrillar polyanions, by adjustment of the extent of sulphation in two independent proteoglycan populations, to achieve an ''average sulphation'' of the total polyanion similar to that of fully sulphated chondroitin sulphate/dermatan sulphate. The balance of synthesis of the two kinds of proteoglycans may be determined by the O2 supply to the avascular cornea. O2 supply may also determine the conversion of chondroitin sulphate into dermatan sulphate.