siRNA high-throughput kinase library screen identifies protein kinase, DNA-activated catalytic polypeptide to play a role in MyD88-induced IFNA2 activation and IL-8 secretion.

The discovery of RNA interference has led to the development of short interfering RNA (siRNA) screening, which has been widely used to study biological pathways. Here, we describe the development and validation of a system suitable to identify cellular genes involved in interferon A2 (IFNA2) promoter activation and interleukin (IL)-8 secretion downstream of MyD88. Forty genes were identified.

The RNA helicase Lgp2 inhibits TLR-independent sensing of viral replication by retinoic acid-inducible gene-I.

The paramyxovirus Sendai (SV), is a well-established inducer of IFN-alphabeta gene expression. In this study we show that SV induces IFN-alphabeta gene expression normally in cells from mice with targeted deletions of the Toll-IL-1 resistance domain containing adapters MyD88, Mal, Toll/IL-1R domain-containing adaptor inducing IFN-beta (TRIF), and TRIF-related adaptor molecule TLR3, or the E3 ubiquitin ligase, TNFR-associated factor 6. This TLR-independent induction of IFN-alphabeta after SV infection is replication dependent and mediated by the RNA helicase, retinoic acid-inducible gene-I (RIG-I) and not the related family member, melanoma differentiation-associated gene 5.

The interferon regulatory factor, IRF5, is a central mediator of toll-like receptor 7 signaling.

Interferon regulatory factors (IRFs) are critical components of virus-induced immune activation and type I interferon regulation. IRF3 and IRF7 are activated in response to a variety of viruses or after engagement of Toll-like receptor (TLR) 3 and TLR4 by double-stranded RNA and lipopolysaccharide, respectively. The activation of IRF5, is much more restricted.

TLR9 signals after translocating from the ER to CpG DNA in the lysosome.

Microbial DNA sequences containing unmethylated CpG dinucleotides activate Toll-like receptor 9 (TLR9). We have found that TLR9 is localized to the endoplasmic reticulum (ER) of dendritic cells (DCs) and macrophages. Because there is no precedent for immune receptor signaling in the ER, we investigated how TLR9 is activated.