Proteomic identification of rainbow trout blood plasma proteins and their relationship to seminal plasma proteins

The characterization of fish blood proteomes is important for the comparative studies of seminal and blood proteins as well as for the analysis of fish immune mechanisms and pathways. In this study LC-MS/MS and 2D DIGE was applied to compare seminal and blood plasma trout proteomes. The 54 differentially abundant proteins identified in seminal plasma are involved in a variety of signaling pathways, including protein ubiqutination, liver X receptor/retinoid X receptor (LXR/RXR) and farnesoid X (FXR)/RXR activation, cell cycle and acute phase signaling. These finding may indicate the prevalence of acute phase signaling pathways in trout seminal plasma, and its essential role in protecting spermatozoa and reproductive tissues. Furthermore our study provides the first in-depth analysis of the rainbow trout blood plasma proteome, with a total of 119 identified proteins. The major proteins of rainbow trout blood plasma were recognized as acute phase proteins. The Ingenuity Pathway Analysis of trout BP plasma proteins indicated that acute phase response signaling, complement system, LXR, FXR-RXR activation and coagulation system are the top canonical pathways associated with trout blood proteins. In conclusion this study enhances the knowledge of the blood origin of trout seminal plasma proteins and the understanding of fish reproductive biology. Additionally our results provide new insight into blood proteins specifically important for fish physiology and innate immunity.

鱼类血液蛋白质组（proteome）的表征，对于精浆（seminal plasma）与血液蛋白质的比较研究，以及鱼类免疫机制与信号通路的解析均具有重要学术价值。本研究采用液相色谱-串联质谱（LC-MS/MS）与双向荧光差异凝胶电泳（2D DIGE）技术，对虹鳟精浆与血液血浆的蛋白质组开展比较分析。本研究在精浆中鉴定出54种差异丰度蛋白质，这些蛋白质参与多条信号通路，涵盖蛋白质泛素化、肝X受体/视黄醇X受体（LXR/RXR）与法尼醇X受体（FXR）/RXR激活通路、细胞周期通路以及急性期信号通路。上述研究结果表明，急性期信号通路在虹鳟精浆中广泛富集，且其在保护精子与生殖组织过程中发挥关键作用。此外，本研究首次对虹鳟血液血浆蛋白质组进行了深度解析，共鉴定得到119种蛋白质。虹鳟血液血浆中的主要蛋白质均被鉴定为急性期蛋白质。对虹鳟血液血浆蛋白质开展的Ingenuity通路分析（Ingenuity Pathway Analysis）显示，急性期应答信号通路、补体系统、LXR、FXR-RXR激活通路以及凝血系统是与虹鳟血液蛋白质关联度最高的经典信号通路。综上，本研究深化了学界对虹鳟精浆蛋白质血液起源的认知，同时完善了对鱼类生殖生物学的理解。此外，本研究结果为与鱼类生理机能与固有免疫密切相关的血液蛋白质提供了全新的研究视角。