HYALURONIC-ACID PRODUCTION AND HYALURONIDASE ACTIVITY IN THE NEWT IRIS DURING LENS REGENERATION
HYALURONIC-ACID PRODUCTION AND HYALURONIDASE ACTIVITY IN THE NEWT IRIS DURING LENS REGENERATION
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DOI：
10.1016/0014-4827(87)90104-2
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发表时间：
1987-09-01
影响因子：
3.7
通讯作者：
DIMITROV, E
中科院分区：
文献类型：
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作者：
KULYK, WM;ZALIK, SE;DIMITROV, E
蝾螈晶状体再生的过程包括虹膜色素上皮细胞的去分化和晶状体纤维的转化。在体内，这种细胞类型的转化仅限于虹膜背侧区域。我们研究了蝾螈虹膜晶状体再生过程中透明质酸积累和内源性透明质酸酶活性的模式。新合成的透明质酸的积累是通过[3H]葡萄糖胺吸收到对透明质酸链霉菌敏感的十六烷基吡啶氯沉淀物质中来估计的。内源性透明质酸酶活性是通过虹膜组织提取物与外源性透明质酸底物孵养后释放的还原性n -乙酰己糖胺的量来测定的。我们发现，在晶状体切除眼睛的再生激活虹膜中，标签与透明质酸的结合始终高于假手术眼睛的对照虹膜。在再生过程中，虹膜背侧（晶状体形成）区域的透明质酸标记高于虹膜腹侧（非晶状体形成）组织。标签在晶状体切除术后10 - 15天内积聚最多，这是虹膜背上皮去分化最明显的时期。正常鸢尾和再生鸢尾均表现出较高的内源性透明质酸酶活性，最适pH为3.5-4.0。虹膜背侧组织的透明质酸酶活性比虹膜腹侧组织高1.7 - 2倍，无论是在切除前还是在整个再生过程中。我们认为，增强的透明质酸积累可能促进虹膜背侧虹膜上皮细胞的去分化，并防止细胞周期中的早熟退出。虹膜背侧高水平的透明质酸酶活性可能促进细胞类型转换所需的细胞外基质成分的周转和重塑。
The process of lens regeneration in newts involves the dedifferentiation of pigmented iris epithelial cells and their subsequent conversion into lens fibers. In vivo this cell-type conversion is restricted to the dorsal region of the iris. We have examined the patterns of hyaluronate accumulation and endogenous hyaluronidase activity in the newt iris during the course of lens regeneration in vivo. Accumulation of newly synthesized hyaluronate was estimated from the uptake of [3H]glucosamine into cetylpyridinium chloride-precipitable material that was sensitive to Streptomyces hyaluronidase. Endogenous hyaluronidase activity was determined from the quantity of reducing N-acetylhexosamine released upon incubation of iris tissue extract with exogenous hyaluronate substrate. We found that incorporation of label into hyaluronate was consistently higher in the regeneration-activated irises of lentectomized eyes than in control irises from sham-operated eyes. Hyaluronate labeling was higher in the dorsal (lens-forming) region of the iris than in ventral (non-lens-forming) iris tissue during the regeneration process. Label accumulation into hyaluronate was maximum between 10 and 15 days after lentectomy, the period of most pronounced dedifferentiation in the dorsal iris epithelium. Both normal and regenerating irises demonstrated a high level of endogenous hyaluronidase activity with a pH optimum of 3.5-4.0. Hyaluronidase activity was 1.7 to 2 times higher in dorsal iris tissue than in ventral irises both prior to lentectomy and throughout the regeneration process. We suggest that enhanced hyaluronate accumulation may facilitate the dedifferentiation of iris epithelial cells in the dorsal iris and prevent precocious withdrawal from the cell cycle. The high level of hyaluronidase activity in the dorsal iris may promote the turnover and remodeling of extracellular matrix components required for cell-type conversion.