Meprin A, the major matrix degrading enzyme in renal tubules, produces a novel nidogen fragment in vitro and in vivo.
Meprin A, the major matrix degrading enzyme in renal tubules, produces a novel nidogen fragment in vitro and in vivo.
复制标题
Meprin A 是肾小管中的主要基质降解酶，可在体外和体内产生新型巢蛋白片段。
DOI：
10.1046/j.1523-1755.1998.00949.x
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Shah,SV
中科院分区：
文献类型：
--
作者：
Walker,PD;Kaushal,GP;Shah,SV
Meprin A 是肾小管中的主要基质降解酶，在体外和体内产生一种新的巢蛋白片段。我们检测了 meprin A（大鼠肾脏中的主要基质降解金属蛋白酶）对层粘连蛋白-巢蛋白复合物的影响。来自最丰富的 55 kDa 片段的 N 端序列信息表明，它是巢蛋白而不是层粘连蛋白的分解产物。与其他蛋白酶产生的超过50个巢蛋白切割位点相比，meprin A诱导的位于氨基酸位置899-900的巢蛋白切割位点（G3结构域中的谷氨酰胺-甘氨酸位点）是独特的。此外，这些数据表明，即使存在层粘连蛋白结合，meprin A 也会降解 nidogen 的 G3 结构域，这通常可以防止蛋白水解降解。 Meprin A 还将纯化的巢蛋白降解为类似的分解产物。鉴于管状基底膜位于细胞的基底侧，meprin A 在顶端刷状缘上的位置使得很难想象 meprin A 在损伤引起的基底膜成分分解中的作用。因此，我们检查了肾小管上皮细胞损伤后，meprin A 发生易位到达下面的基底膜的可能性。肾缺血再灌注后，meprin A 染色发生显着变化，meprin A 现在分布在整个肾小管细胞的细胞质中，并直接粘附在肾小管基底膜上。这与皮质髓质交界处小管刷状缘的通常线性染色形成对比。这些数据提供了明确的证据，表明损伤后，meprin A 会重新分布和/或粘附到肾小管基底膜上。由于在我们的体外研究中，我们鉴定了一种独特的 meprin 诱导的 55 kDa nidogen 分解产物，因此在大鼠肾缺血再灌注损伤后，还检查了尿液中是否存在 nidogen 降解产物。蛋白质印迹显示，早在缺血再灌注损伤后的第一天，尿液中 55 kDa nidogen 片段就显着增加，并持续六天。总而言之，这些体内数据强烈支持这样的观点，即巢蛋白分解产物是肾小管缺血再灌注损伤后meprin A部分降解肾小管基底膜的结果。
Meprin A, the major matrix degrading enzyme in renal tubules, produces a novel nidogen fragmentin vitroandin vivo.We examined the effect of meprin A, the major matrix degrading metalloproteinase in rat kidney, on the laminin-nidogen complex. N-terminal sequence information from the most abundant 55 kDa fragment revealed that it was a breakdown product of nidogen rather than laminin. In comparison with over 50 nidogen cleavage sites produced by other proteases, the meprin A-induced nidogen cleavage site at amino acid position 899-900, a glutamine-glycine site in the G3 domain, is unique. In addition, these data demonstrate that meprin A degrades the G3 domain of nidogen even in the presence of laminin binding, which usually accords protection from proteolytic degradation. Meprin A also degraded purified nidogen into similar breakdown products. Given that the tubular basement membrane is located on the basilar side of the cell, the location of meprin A on the apical brush border makes it difficult to envision a role for meprin A in injury-induced basement membrane component breakdown. Thus, we examined the possibility that following renal tubular epithelial cell injury, meprin A undergoes a translocation to reach the underlying basement membrane. After renal ischemia-reperfusion there was a marked alteration in meprin A staining with meprin A now distributed throughout the renal tubular cell cytoplasm and directly adherent to the tubular basement membrane. This was in contrast to the usual linear staining of the brush border of tubules in the corticomedullary junction. These data provide unequivocal evidence that following injury, meprin A undergoes redistribution and/or adherence to the tubular basement membrane. Since in ourin vitrostudies, we identified a distinct meprin-induced 55 kDa nidogen breakdown product, the urine was also examined for the presence of nidogen degradation products after rat renal ischemia-reperfusion injury. Western blots showed a marked increase in the urinary 55 kDa nidogen fragment as early as the first day following ischemia-reperfusion injury and continuing for six days. Taken together, thesein vivodata strongly support the notion that the nidogen breakdown products are the result of partial degradation of tubular basement membrane by meprin A following renal tubular ischemia-reperfusion injury.