Intragenic duplication: a novel mutational mechanism in hereditary pancreatitis.
Intragenic duplication: a novel mutational mechanism in hereditary pancreatitis.
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DOI：
10.1097/mpa.0b013e3182152fdf
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发表时间：
2011-05
期刊：
影响因子：
2.9
通讯作者：
Sahin-Tóth M
中科院分区：
文献类型：
--
作者：
Joergensen MT;Geisz A;Brusgaard K;Schaffalitzky de Muckadell OB;Hegyi P;Gerdes AM;Sahin-Tóth M
在来自丹麦的一个遗传性胰腺炎家族中，我们发现了一种新的人阳离子胰蛋白酶原（PRSS 1）基因（c.63_71dup）外显子2中9个核苷酸的基因内重复，该重复在氨基酸水平上导致阳离子胰蛋白酶原激活肽（p.K23_I24insIDK）内插入3个氨基酸。本研究的目的是描述这种独特的遗传改变对人阳离子胰蛋白酶原功能的影响。重组产生野生型和突变型阳离子胰蛋白酶原，并纯化至均一。胰蛋白酶原活化后进行酶测定和SDS-PAGE。从转染的HEK 293 T细胞测量胰蛋白酶原分泌。携带p.K23_I24insIDK突变的重组阳离子胰蛋白酶原表现出>10倍的自激活增加。人组织蛋白酶B的激活也加速了10倍。p.K23_I24insIDK突变体从转染细胞的分泌减少，与细胞内自激活一致。这是第一次报告的PRSS 1基因内的基因内重复导致遗传性胰腺炎。组织蛋白酶B对p.K23_I24insIDK的加速激活是一种独特的生化特性，在任何其他胰腺炎相关胰蛋白酶原突变体中均未发现。相反，新突变体的强大的自激活证实了这样的概念，即增加的自激活是遗传性胰腺炎的疾病相关机制。
In a hereditary pancreatitis family from Denmark we identified a novel intragenic duplication of 9 nucleotides in exon-2 of the human cationic trypsinogen (PRSS1) gene (c.63_71dup) which at the amino-acid level resulted in the insertion of three amino acids within the activation peptide of cationic trypsinogen (p.K23_I24insIDK). The aim of the present study was to characterize the effect of this unique genetic alteration on the function of human cationic trypsinogen. Wild-type and mutant cationic trypsinogens were produced recombinantly and purified to homogeneity. Trypsinogen activation was followed by enzymatic assays and SDS-PAGE. Trypsinogen secretion was measured from transfected HEK 293T cells. Recombinant cationic trypsinogen carrying the p.K23_I24insIDK mutation exhibited >10-fold increased autoactivation. Activation by human cathepsin B was also accelerated by 10-fold. Secretion of the p.K23_I24insIDK mutant from transfected cells was diminished, consistent with intracellular autoactivation. This is the first report of an intragenic duplication within the PRSS1 gene causing hereditary pancreatitis. The accelerated activation of p.K23_I24insIDK by cathepsin B is a unique biochemical property not found in any other pancreatitis-associated trypsinogen mutant. In contrast, the robust autoactivation of the novel mutant confirms the notion that increased autoactivation is a disease-relevant mechanism in hereditary pancreatitis.