A novel protease inhibitor of the α2-macroglobulin family expressed in the human epidermis
A novel protease inhibitor of the α2-macroglobulin family expressed in the human epidermis
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DOI：
10.1074/jbc.m508017200
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发表时间：
2006-03-03
影响因子：
4.8
通讯作者：
Guerrin, M
中科院分区：
文献类型：
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作者：
Galliano, MF;Toulza, E;Guerrin, M
在人表皮中晚期表达基因的大规模分析过程中，我们鉴定了α（2）-巨球蛋白（α 2 M）蛋白酶抑制剂家族的新成员A2 ML 1（α（2）-巨球蛋白样1）。与A2 M和PZP一样，A2 ML 1位于染色体12p13.31上。A2 ML 1编码1454个氨基酸，符合α 2 M的特征：1）氨基酸序列高度保守，包括大部分半胱氨酸位置; 2）推测的中央诱饵结构域; 3）典型的硫酯序列。北方杂交和逆转录酶- PCR研究显示，一个单一的5- kb的A2 ML 1 mRNA，主要在表皮颗粒角质形成细胞。A2 ML 1也在胎盘、胸腺和睾丸中转录。通过Western印迹分析，检测到α 2 ML 1作为单体，类似于人表皮中的180- kDa蛋白。体外角质形成细胞分化与表达水平增加相关。通过免疫组织化学，在表皮的颗粒层中的角蛋白体内检测到α 2 ML 1，并且在最上面的颗粒层和皮质层之间的细胞外空间中作为分泌产物。重组α 2 ML 1显示对胰凝乳蛋白酶，木瓜蛋白酶，嗜热菌蛋白酶，枯草杆菌蛋白酶A，并在较小程度上，弹性蛋白酶，但不胰蛋白酶的抑制活性。与胰凝乳蛋白酶和胰凝乳蛋白酶样激肽释放酶7蛋白酶一起孵育表明α 2 ML 1共价结合这些蛋白酶，这是该家族其他成员共有的特征。因此，α 2 ML 1是在表皮中检测到的第一个α 2 M家族成员。它可能通过抑制细胞外蛋白酶在脱屑过程中发挥重要作用。
In the course of a large scale analysis of late- expressed genes in the human epidermis, we identified a new member of the alpha(2)- macroglobulin (alpha 2M) protease inhibitor family, A2ML1 ( for alpha(2)- macroglobulin-like 1). Like A2M and PZP, A2ML1 is located on chromosome 12p13.31. A2ML1 encodes a protein of 1454 amino acids, which fits the characteristics of alpha 2Ms: 1) strong conservation in amino acid sequence including most of cysteine positions with alpha 2M; 2) a putative central bait domain; 3) a typical thiol ester sequence. Northern blot and reverse transcriptase- PCR studies revealed a single 5- kb A2ML1 mRNA, mainly in the epidermis granular keratinocytes. A2ML1 is also transcribed in placenta, thymus, and testis. By Western blot analysis, alpha 2ML1 is detected as a monomeric, similar to 180- kDa protein in human epidermis. In vitro keratinocyte differentiation is associated with increased expression levels. By immunohistochemistry, alpha 2ML1 was detected within keratinosomes in the granular layer of the epidermis, and as a secreted product in the extracellular space between the uppermost granular layer and the cornified layer. Recombinant alpha 2ML1 displayed inhibitory activity toward chymotrypsin, papain, thermolysin, subtilisin A, and to a lesser extent, elastase but not trypsin. Incubation with chymotrypsin and the chymotrypsin- like kallikrein 7 protease indicated that alpha 2ML1 binds covalently to these proteases, a feature shared with other members of the family. Therefore, alpha 2ML1 is the first alpha 2M family member detected in the epidermis. It may play an important role during desquamation by inhibiting extracellular proteases.