An amphioxus TLR with dynamic embryonic expression pattern responses to pathogens and activates NF-kappaB pathway via MyD88.
A big bang expansion of the Vertebrate-type (V-type) TLRs was reported in amphioxus. To shed lights on its implications, a unique TLR which is reversely inserted into an intron of amphioxus PSMB7-10 by retrotransposition in the highly polymorphic proto-MHC region was cloned from Chinese amphioxus (Branchiostoma belcheri tsingtauense) and named as bbtTLR1. In situ assays showed that bbtTLR1 was predominantly expressed in pharynx and gut from larva to adult stages, which are considered as the first frontlines of amphioxus defense system. Acute immune challenges revealed that the expression of bbtTLR1 was stimulated by bacteria and their cell wall components, while suppressed by Glucan and Poly I:C in the digestive system. Amphioxus also had dozens of TIR adaptors from which we cloned bbtMyD88. BbtMyD88 expressed in 293T cells led to the activation of NF-kappaB pathway through its DEATH and middle domains. Moreover, this activation could be enhanced by bbtTLR1 through the direct association with bbtMyD88. In summary, this study provides evidence for the immune-relation of amphioxus V-type TLRs, and suggests that amphioxus TLR1 and MyD88 represent a basic evolutionary pathway.
Yuan
Shaochun
S
State Key Laboratory of Biocontrol, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, 135 Xingangxi Rd, Guangzhou 510275, People's Republic of China.
Huang
Shengfeng
S
Zhang
Wei
W
Wu
Tao
T
Dong
Meiling
M
Yu
Yanhong
Y
Liu
Tong
T
Wu
Kui
K
Liu
Huiling
H
Yang
Manyi
M
Zhang
Hongwei
H
Xu
Anlong
A
D000818:Animals; D002460:Cell Line; D002816:Chordata, Nonvertebrate / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D004625:Embryo, Nonmammalian / Q000378:metabolism; D006801:Humans; D007814:Larva / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D013211:Staphylococcus aureus / Q000502:physiology; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*; D041261:Vibrio vulnificus / Q000502:physiology
D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D051193:Toll-Like Receptors