Abstract
Toll-like receptors (TLRs) are well-described pattern recognition receptors that recognize different pathogen-associated molecular patterns (PAMPs) to activate innate immune responses. TLR1 forms a heterodimer with TLR2 that works to identify PAMPs including bacterial components. In the present study, we identified a
TLR1
homolog from rock bream
Oplegnathus fasciatus
(
RbTLR1
) and characterized it at the genomic level. The complete coding sequence of
RbTLR1
was 2406 bp in length and encoded an 802 amino acid protein possessing a calculated molecular mass of 90.7 kDa and typical TLR domain architecture. A single exon spanned the genomic length (2931 bp) of
RbTLR1
. Phylogenetic analysis showed a close evolutionary relationship between RbTLR1 and its fish orthologs. Using quantitative real time polymerase chain reaction, we detected
RbTLR1
mRNA in all the tissues examined, suggesting its merely universal tissue expression.
RbTLR1
was expressed strongly in the spleen, kidney, and liver. Following immune stimulation by bacterial pathogens and mitogens,
RbTLR1
transcript levels were elevated at various time points post stimulation. Moreover, injection of a viral stimulant, polyinosinic:polycytidylic acid, and rock bream iridovirus altered the basal transcription of
RbTLR1
. Collectively, these data showed that
RbTLR1
is transcriptionally regulated in response to bacterial and viral stimulation, suggesting its putative importance in host immune defense.