Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Ocean University of China, PR China.
Laboratory of Pathology and Immunology of Aquatic Animals, KLMME, Ocean University of China, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao Marine Science and Technology Center, Qingdao, Shandong 266237, PR China.
Int J Biol Macromol. 2024 Oct;277(Pt 1):134127. doi: 10.1016/j.ijbiomac.2024.134127. Epub 2024 Jul 23.
Mucins secreted by mucous cells constitute a core part of the defense line against the invasion of pathogens. However, mucins' structure and immunological functions remain largely unknown in teleost fish. In this study, two typical mucins, Muc2 and Muc5ac of flounder (Paralichthys olivaceus), were cloned and their physicochemical properties, structure and conservation were analyzed. Notably, specific antibodies against flounder Muc2 and Muc5ac were developed. It was verified at the gene and protein level that Muc2 was expressed in the hindgut and gills but not in the skin, while Muc5ac was expressed in the skin and gills but not in the hindgut. After flounders were immunized by immersion with inactivated Edwardsiella tarda, Muc2 and Muc5ac were significantly upregulated at both the gene expression and protein levels, and Muc2/Muc5ac mucous cells proliferated and increased secretion of Muc2 and Muc5ac. Moreover, Muc2 and Muc5ac exerted retention and clearance effects on E. tarda in a short period (within 1 dpi). These results revealed the characterization of fish mucins Muc2 and Muc5ac at the protein level and clarified the role of mucins as key guardians to maintain the mucus barrier, which advanced our understanding of teleost mucosal barrier.
黏蛋白由黏液细胞分泌，构成了抵御病原体入侵的防线的核心部分。然而，在硬骨鱼类中，黏蛋白的结构和免疫学功能在很大程度上仍不清楚。在本研究中，我们克隆了牙鲆（Paralichthys olivaceus）的两种典型黏蛋白 Muc2 和 Muc5ac，并分析了它们的理化性质、结构和保守性。值得注意的是，我们制备了针对牙鲆 Muc2 和 Muc5ac 的特异性抗体。通过基因和蛋白水平的验证，我们发现 Muc2 仅在后肠和鳃中表达，而不在皮肤中表达，而 Muc5ac 则在皮肤和鳃中表达，在后肠中不表达。牙鲆经浸泡免疫灭活的迟缓爱德华氏菌后，Muc2 和 Muc5ac 在基因表达和蛋白水平上均显著上调，Muc2/Muc5ac 黏液细胞增殖并增加了 Muc2 和 Muc5ac 的分泌。此外，Muc2 和 Muc5ac 在短时间内（1dpi 内）对 E. tarda 具有滞留和清除作用。这些结果揭示了鱼类黏蛋白 Muc2 和 Muc5ac 在蛋白水平上的特征，并阐明了黏蛋白作为维持黏液屏障的关键保护者的作用，这加深了我们对硬骨鱼黏膜屏障的理解。
