Icahn School of Medicine at Mount Sinai, New York, NY, USA.
Kansas State University, Manhattan, KS, USA.
FASEB J. 2021 Feb;35(2):e21310. doi: 10.1096/fj.202001120RR.
ADAMTS proteases mediate biosynthesis and breakdown of secreted extracellular matrix (ECM) molecules in numerous physiological and disease processes. In addition to their catalytic domains, ADAMTS proteases contain ancillary domains, which mediate substrate recognition and ECM binding and confer distinctive properties and roles to individual ADAMTS proteases. Although alternative splicing can greatly expand the structural and functional diversity of ADAMTS proteases, it has been infrequently reported and functional consequences have been rarely investigated. Here, we characterize the structural and functional impact of alternative splicing of ADAMTS17, mutations in which cause Weill-Marchesani syndrome 4. Two novel ADAMTS17 splice variants, ADAMTS17A and ADAMTS17B, were investigated by structural modeling, mass spectrometry, and biochemical approaches. Our results identify a novel disulfide-bridged insertion in the ADAMTS17A spacer that originates from inclusion of a novel exon. This insertion results in differential autoproteolysis of ADAMTS17, and thus, predicts altered proteolytic activity against other substrates. The second variant, ADAMTS17B, results from an in-frame exon deletion and prevents ADAMTS17B secretion. Thus, alternative splicing of the ADAMTS spacer significantly regulates the physiologically relevant proteolytic activity of ADAMTS17, either by altering proteolytic specificity (ADAMTS17A) or by altering cellular localization (ADAMTS17B).
ADAMTS 蛋白酶在许多生理和疾病过程中调节细胞外基质 (ECM) 分子的生物合成和分解。除了催化结构域外，ADAMTS 蛋白酶还含有辅助结构域，这些结构域介导底物识别和 ECM 结合，并赋予单个 ADAMTS 蛋白酶独特的特性和作用。尽管选择性剪接可以极大地扩展 ADAMTS 蛋白酶的结构和功能多样性，但这种情况很少见，其功能后果也很少被研究。在这里，我们研究了 ADAMTS17 的选择性剪接对结构和功能的影响，该基因突变会导致 Weill-Marchesani 综合征 4。通过结构建模、质谱和生化方法研究了两种新的 ADAMTS17 剪接变体，ADAMTS17A 和 ADAMTS17B。我们的结果鉴定了 ADAMTS17A 间隔子中一个新的二硫键桥接插入，该插入来源于一个新外显子的包含。这种插入导致 ADAMTS17 的差异自切割，因此，预测对其他底物的水解活性发生改变。第二个变体 ADAMTS17B 是由于内含子缺失而导致的，阻止了 ADAMTS17B 的分泌。因此，ADAMTS 间隔子的选择性剪接通过改变蛋白水解特异性（ADAMTS17A）或改变细胞定位（ADAMTS17B），显著调节 ADAMTS17 的生理相关蛋白水解活性。
