SELECTIVE PRESENCE OF ACID-HYDROLASES IN THE INTERPHOTORECEPTOR MATRIX
SELECTIVE PRESENCE OF ACID-HYDROLASES IN THE INTERPHOTORECEPTOR MATRIX
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DOI：
10.1016/s0014-4835(89)80027-2
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发表时间：
1989-12-01
影响因子：
3.4
通讯作者：
ADLER, AJ
中科院分区：
文献类型：
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作者：
ADLER, AJ
Adler和Martin（1983，Curr.眼研究2. 359 - 66）发现组织蛋白酶D存在于牛光感受器间基质（IPM）的粗制品中。本研究的目的是确定，通过调查几个酸水解酶在纯IPM样品中，是否存在丰富的水解酶在RPE溶酶体也作为正常成分的IPM。通过在神经视网膜和RPE之间引入缓冲液的小泡，从牛眼制备IPM。这些IPM样品不受周围组织的显著污染;它们含有IRBP作为其唯一的主要蛋白质，并且具有可忽略的量的乳酸脱氢酶和ROS特异性蛋白质。大多数酸性水解酶通过测量适当衍生物水解后释放的4-甲基伞形酮进行荧光测定;组织蛋白酶的底物是血红蛋白。在IPM中发现的酶的量远不均匀，并且不能与RPE或视网膜匀浆中的酶活性相关。IPM中的水解酶的量从β-半乳糖苷酶（RPE水平的28%），通过N-乙酰基-β-氨基葡糖苷酶（20%），α-岩藻糖苷酶（15%）β-葡糖醛酸糖苷酶（12%），α-葡糖苷酶（8%）、组织蛋白酶（7%）、α-葡萄糖苷酶（8%）、α-葡萄糖苷酶（7%）。甘露糖苷酶（7%），降至β-葡萄糖苷酶、酸性磷酸酶和酸性脂肪酶（痕量，<1%）。这些结果与Wilcox（1987）发现的由培养的人RPE细胞分泌到培养基中的酶的相对量一致。此外，IPM中水解酶的等级顺序与I细胞疾病中人成纤维细胞分泌（但未重新捕获）的水解酶的等级顺序相同。从这些相关性的结论是，溶酶体酶可能分泌，作为一个正常的过程，由RPE到IPM，在那里他们可能有一个作用，在消化脱落的外节和分解代谢IPM组件。
Adler and Martin (1983, Curr. Eye Res. 2. 359-66) found cathepsin D to be present in crude preparations of bovine interphotoreceptor matrix (IPM). The purpose of the present study was to determine, by investigating several acid hydrolases in purer IPM samples, whether hydrolytic enzymes abundant in RPE lysosomes were present also as normal components of the IPM. IPM was prepared from bovine eyes by the introduction of a small bleb of buffer between the neural retina and the RPE. These IPM samples were free from significant contamination by surrounding tissues; they contained IRBP as their only major protein, and had negligible amounts of lactate dehydrogenase and ROS-specific proteins. Most acid hydrolases were assayed fluorometrically by measuring the 4-methylumbelliferone released upon hydrolysis of appropriate derivatives; the substrate for cathepsin was hemoglobin. The amounts of the enzymes found in the IPM were far from uniform and could not be correlated with enzyme activities in either RPE or retina homogenates. The hydrolases in the IPM varied in amount from .beta.-galactosidase (28% of the RPE level), through N-acetyl-.beta.-glucosaminidase (20%), .alpha.-fucosidase (15%) .beta.-glucuronidase (12%), .alpha.-glucosidase (8%), cathepsin (7%), .alpha.-mannosidase (7%), down to .beta.-glucosidase, acid phosphatase, and acid lipase (trace amounts, < 1%). These results agree with the relative amounts of enzymes found by Wilcox (1987) to be secreted into the medium by cultured human RPE cells. Furthermore, the rank order of hydrolases in the IPM is the same as that for hydrolases secreted (but not recaptured) by human fibroblasts in I-cell disease. The conclusion from these correlations is that lysosomal enzymes are probably secreted, as a normal process, by the RPE into the IPM, where they may have a role in digesting shed outer segments and in catabolizing IPM components.