Alternate transcription of the Toll-like receptor signaling cascade.
BACKGROUND
Alternate splicing of key signaling molecules in the Toll-like receptor (Tlr) cascade has been shown to dramatically alter the signaling capacity of inflammatory cells, but it is not known how common this mechanism is. We provide transcriptional evidence of widespread alternate splicing in the Toll-like receptor signaling pathway, derived from a systematic analysis of the FANTOM3 mouse data set. Functional annotation of variant proteins was assessed in light of inflammatory signaling in mouse primary macrophages, and the expression of each variant transcript was assessed by splicing arrays.


RESULTS
A total of 256 variant transcripts were identified, including novel variants of Tlr4, Ticam1, Tollip, Rac1, Irak1, 2 and 4, Mapk14/p38, Atf2 and Stat1. The expression of variant transcripts was assessed using custom-designed splicing arrays. We functionally tested the expression of Tlr4 transcripts under a range of cytokine conditions via northern and quantitative real-time polymerase chain reaction. The effects of variant Mapk14/p38 protein expression on macrophage survival were demonstrated.


CONCLUSIONS
Members of the Toll-like receptor signaling pathway are highly alternatively spliced, producing a large number of novel proteins with the potential to functionally alter inflammatory outcomes. These variants are expressed in primary mouse macrophages in response to inflammatory mediators such as interferon-gamma and lipopolysaccharide. Our data suggest a surprisingly common role for variant proteins in diversification/repression of inflammatory signaling.
Wells
Christine A
CA
Eskitis Institute for Cell and Molecular Therapies, School of Biological and Biomedical Sciences, Griffith University, Brisbane 4111, Australia. c.wells@griffith.edu.au
Chalk
Alistair M
AM
Forrest
Alistair
A
Taylor
Darrin
D
Waddell
Nic
N
Schroder
Kate
K
Himes
S Roy
SR
Faulkner
Geoffrey
G
Lo
Sandra
S
Kasukawa
Takeya
T
Kawaji
Hideya
H
Kai
Chikatoshi
C
Kawai
Jun
J
Katayama
Shintaro
S
Carninci
Piero
P
Hayashizaki
Yoshihide
Y
Hume
David A
DA
Grimmond
Sean M
SM
D017398:Alternative Splicing; D000818:Animals; D017931:DNA Primers; D020869:Gene Expression Profiling; D014644:Genetic Variation; D016678:Genome; D008322:Mammals; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics; D051197:Toll-Like Receptor 4 / Q000235:genetics*; D051193:Toll-Like Receptors / Q000235:genetics*; D014158:Transcription, Genetic
D017931:DNA Primers; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors