The truncated MyD88s negatively regulates TLR2 signal on expression of IL17-1 in oyster Crassostrea gigas. (August 2022)

• Record Type: Journal Article
• Authors: Fan, Siqi; Wang, Weilin; Li, Jialuo; Cao, Wanqing; Li, Qing; Wu, Shasha; Wang, Lingling; Song, Linsheng
• Is Part Of: Developmental and comparative immunology. Volume 133(2022)
• Publication Date: 2022-08
• Subjects: Crassostrea gigas -- TLR signal -- MyD88 -- IL17-1 -- Immune regulation; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2022.104446
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Toll like receptor (TLR) signaling plays a key role in the innate immune recognition and inflammatory regulation in both vertebrates and invertebrates. The expanded TLR signaling components, including 83 TLRs and 10 MyD88s, have been reported in the genome of the Pacific oyster Crassostrea gigas . In the present study, one endogenous TLR (designated Cg TLR2) and two MyD88s (including a full-length Cg MyD88-2 containing intact TIR domain and Death-domain, and a truncated Cg MyD88s with only TIR domain) were identified from oyster C. gigas . Cg TLR2 was highly expressed in haemocytes, especially in granulocytes. The recombinant protein of the extracellular LRR domains of Cg TLR2 recognized and bound a variety of PAMPs with the strongest binding capability to LPS. The recombinant protein of intracellular TIR domain of Cg TLR2 was able to bind the recombinant proteins of r Cg MyD88-2 (KD = 1.96 × 10 −9 M) and r Cg MyD88s (KD = 4.84 × 10 −8 M), with higher affinity towards r Cg MyD88-2. After Vibrio splendidus stimulation, the mRNA expression levels of Cg TLR2 and Cg MyD88-2 were rapidly up-regulated at early stage of immune response (from the 3rd hours after V. splendidus stimulation), while that of Cg MyD88s did not change until 24 h post stimulation. When Cg TLR2 was knocked-down by siRNA interference, the expression levels of Cg MyD88-2 and Cg MyD88s decreased significantly, concomitant with the down-regulation of expression of Cg IL17-1. After the expression of Cg MyD88-2 was interfered, the expressions of Cg MyD88s and Cg IL17-1 were all decreased. In contrast, after the expression of Cg MyD88s was interfered, the expressions of Cg MyD88-2 and Cg IL17-1 all increased. The results showed that Cg MyD88s played a negative role in the regulation of Cg TLR2 on inflammatory factor Cg IL17-1. Graphical abstract: Image 1 Highlights: A endogenous Cg TLR2, a canonical Cg MyD88-2 and a Cg MyD88s with only TIR domain were identified from oyster. The Cg TLR2- Cg MyD88-2 signal regulated the production of Cg IL17-1 at the early stage of immune response. Cg MyD88s negatively mediated the Cg TLR2- Cg MyD88-2 signal at the late immune stage of immune response.