TLR7 is required for optimal immune defense against bacterial infection in tongue sole (Cynoglossus semilaevis).
In mammals as well as in teleost, toll-like receptor 7 (TLR7) is known to be involved in antiviral immunity by recognizing viral RNA. However, the antibacterial potential of fish TLR7 is unclear. In this study, we analyzed the TLR7 of tongue sole (Cynoglossus semilaevis), CsTLR7, and examined its potential involvement in antibacterial immunity. CsTLR7 is composed of 1052 amino acid residues and shares 64.0%-75.9% overall sequence identities with known teleost TLR7. CsTLR7 possesses a toll/interleukin-1 receptor domain and six leucine-rich repeats. Constitutive expression of CsTLR7 occurred in relatively high levels in kidney, spleen and liver. Bacterial infection upregulated CsTLR7 expression, whereas viral infection downregulated CsTLR7 expression. Knockdown of CsTLR7 significantly enhanced bacterial dissemination in the tissues of tongue sole. Treatment of tongue sole with the imidazoquinoline compound R848 (TLR7 activator) and the endosomal acidification inhibitor chloroquine (TLR7 inhibitor) caused enhanced and reduced resistance against bacterial infection respectively. These results indicate that CsTLR7 plays an essential role in the antibacterial immunity of tongue sole.
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China; Function Laboratory for Marine Biology and Biotechnology, Qingdao National Oceanography Laboratory, Qingdao, China.
Xue-peng
XP
Li
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Function Laboratory for Marine Biology and Biotechnology, Qingdao National Oceanography Laboratory, Qingdao, China. Electronic address: lsun@qdio.ac.cn.
Li
L
Sun
D000595:Amino Acid Sequence; D000818:Animals; D004266:DNA Virus Infections / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D005393:Fish Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005412:Flatfishes; D005786:Gene Expression Regulation; D007113:Immunity, Innate; D007497:Iridoviridae / Q000502:physiology; D011552:Pseudomonas Infections / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D011551:Pseudomonas fluorescens / Q000502:physiology; D016415:Sequence Alignment / Q000662:veterinary; D051199:Toll-Like Receptor 7 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D029941:Fish Proteins; D051199:Toll-Like Receptor 7
Antibacterial; Chloroquine; Cynoglossus semilaevis; Innate immunity; R848; Toll-like receptor