Crow Ryley S, Grayfer Leon, Smith L Courtney
Department of Biological Sciences, George Washington University, Washington, DC, United States.
Front Immunol. 2025 Jan 28;15:1496832. doi: 10.3389/fimmu.2024.1496832. eCollection 2024.
The California purple sea urchin, , relies exclusively on an innate immune system to survive in its pathogen rich marine environment. Central to this defense is the gene family that is unique to the euechinoid group of echinoderms. These genes were initially identified based on their striking upregulation in response to immune challenge. The gene family encodes structurally similar proteins with a wide range of sequence diversity within and among individual sea urchins. A recombinant (r)SpTrf protein interacts specifically with a variety of non-self targets. Other rSpTrf proteins cross-linked to inert beads show distinct functions for cell binding and augmenting phagocytosis . However, whether the rSpTrf proteins bind to sea urchin phagocytes, and the cellular consequences of binding are largely unexplored.
rSpTrf protein binding to, and responses by phagocytes was investigated by cytology, flow cytometry, binding competitions using In-cell ELISA, and gene expression analyses.
Soluble rSpTrf proteins bind specifically and exclusively to both live and fixed polygonal and small phagocytes. The different rSpTrf proteins appear to bind shared receptor(s) or other form of cell surface binding site. The phagocyte response to bound rSpTrf proteins culminates in modulated expression of the gene family as well as other immune-related genes.
These findings underscore the multifaceted and dynamic functions of SpTrf proteins within the innate immune system of the purple sea urchin. Their varied functions enable a robust immune response while also providing a unique modulatory mechanism by which response levels are controlled and adjusted to the level of the foreign threat.
加利福尼亚紫海胆完全依靠先天免疫系统在富含病原体的海洋环境中生存。这种防御的核心是棘皮动物真海胆类群特有的基因家族。这些基因最初是根据它们在免疫挑战后显著上调而被鉴定出来的。该基因家族编码结构相似的蛋白质，在个体海胆内部和之间具有广泛的序列多样性。一种重组（r）SpTrf蛋白与多种非自身靶标特异性相互作用。其他与惰性珠子交联的rSpTrf蛋白在细胞结合和增强吞噬作用方面表现出不同的功能。然而，rSpTrf蛋白是否与海胆吞噬细胞结合，以及结合的细胞后果在很大程度上尚未得到探索。
通过细胞学、流式细胞术、使用细胞内ELISA的结合竞争以及基因表达分析，研究rSpTrf蛋白与吞噬细胞的结合以及吞噬细胞的反应。
可溶性rSpTrf蛋白特异性且仅与活的和固定的多边形及小吞噬细胞结合。不同的rSpTrf蛋白似乎结合共享的受体或其他形式的细胞表面结合位点。吞噬细胞对结合的rSpTrf蛋白的反应最终导致该基因家族以及其他免疫相关基因的表达受到调节。
这些发现强调了SpTrf蛋白在紫海胆先天免疫系统中的多方面和动态功能。它们多样的功能能够实现强大的免疫反应，同时还提供了一种独特的调节机制，通过该机制可以控制反应水平并根据外来威胁的程度进行调整。
