The cathepsin C, a lysosomal cysteine protease, involves the modulation of immune and inflammatory responses in living organisms. However, the knowledge on cathepsin C in red swamp crayfish (Procambarus clarkii), a freshwater crustacean with economic values, remained unclear. In the present study, we provide identification and molecular characterization of cathepsin C from P. clarkii. (Hereafter Pc-cathepsin C). The Pc-cathepsin C cDNA contained a 1356 bp open reading frame that encoded a protein of 451 amino acid residues. The deduced amino acid sequence comprised of cathepsin C exclusion domain and pept_C1 domain, and also catalytic residues (Cys²⁴⁸, His³⁹⁵ and Asn⁴¹⁷). Analysis of the transcriptional patterns of the Pc-cathepsin C gene revealed that it was broadly distributed in various tissues of P. clarkii, and it was more abundant in the hepatopancreas and gut. Following a challenge with viral and bacterial pathogen-associated molecular patterns, the expression of Pc-cathepsin C was strongly enhanced at different time points. The knockdown of Pc-cathepsin C, altered the expression of immune-responsive genes, suggesting its immunoregulatory role in P. clarkii. This study has identified and provided the immunoregulatory function of Pc-cathepsin C, which will contribute to further investigation of the molecular mechanism of cathepsin C in crustaceans.

组织蛋白酶C是一种溶酶体半胱氨酸蛋白酶，涉及活生物体中免疫和炎症反应的调节。然而，关于红色沼泽小龙虾（Procambarus clarkii）（一种具有经济价值的淡水甲壳动物）中组织蛋白酶C的知识仍不清楚。在本研究中，我们提供了克拉克假单胞菌组织蛋白酶C的鉴定和分子表征。（此后为Pc-蛋白酶C）。的PC-蛋白酶C cDNA的含有1356个碱基的是编码的451的蛋白质的氨基酸残基的开放阅读框。推导的氨基酸序列由组织蛋白酶C排他结构域和pept_C1结构域以及催化残基组成（Cys ²⁴⁸，His ³⁹⁵和Asn ⁴¹⁷）。对Pc-cathepsin C基因转录模式的分析表明，它广泛分布于克拉克毕赤酵母的各种组织中，并且在肝胰腺和肠道中含量更高。受到病毒和细菌病原体相关分子模式的挑战后，Pc-cathepsin C的表达在不同时间点得到了强烈增强。Pc-cathepsin C的敲低改变了免疫应答基因的表达，表明其在克拉克疟原虫中的免疫调节作用。这项研究已经确定并提供了Pc-cathepsin C的免疫调节功能，这将有助于进一步研究甲壳动物组织蛋白酶C的分子机制。