Interaction between interferon-stimulated gene 56 and melanoma differentiation-associated gene 5 in Toll-like receptor 3 signaling in normal human mesangial cells.
OBJECTIVE
Toll-like receptor 3 (TLR3) is a pathogen recognition receptor against viral double-stranded RNA. TLR3 signaling is important in antiviral responses, but inappropriate TLR3 signaling may be related with inflammatory renal diseases. Interferon (IFN)-stimulated gene 56 (ISG56) is an IFN-inducible gene that encodes a multifunctional protein with 6 tetratricopeptide motifs and is thought to be involved in antiviral reactions, but the role of ISG56 in TLR3 signaling in mesangial cells is not known well.


METHODS
Normal human mesangial cells were cultured and treated with a synthetic TLR3 ligand polyinosinic-polycytidylic acid, and the expression of ISG56 was analyzed using real-time RT-PCR and Western blot analyses. Using an RNA-interfering technique, involvement of TLR3, IFN-β, melanoma differentiation-associated gene 5 (MDA5) or retinoic acid-inducible gene-I (RIG-I) in ISG56 expression, and of ISG56 in the expression of MDA5, RIG-I, CXCL10 and CCL5 was examined.


RESULTS
Treatment of cells with polyinosinic-polycytidylic acid induced ISG56. ISG56 induction was inhibited by knockdown of TLR3 or IFN-β, and knockdown of ISG56 resulted in the decreased expression of MDA5, RIG-I, CXCL10 and CCL5. RNA interference against MDA5 decreased ISG56 expression.


CONCLUSIONS
ISG56 was induced by TLR3 signaling via newly synthesized IFN-β. ISG56 is involved in the expression of MDA5, RIG-I, CXCL10 and CCL5, and ISG56 and MDA5 may constitute a positive-feedback loop. ISG56 may play a role in immune and inflammatory reactions induced by TLR3 signaling in human mesangial cells.
Department of Vascular Biology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan. timaizum@cc.hirosaki-u.ac.jp
Tadaatsu
T
Imaizumi
Tomomi
T
Aizawa-Yashiro
Tomoh
T
Matsumiya
Hidemi
H
Yoshida
Shojiro
S
Watanabe
Kazushi
K
Tsuruga
Tetsuya
T
Tatsuta
Fei
F
Xing
Ryo
R
Hayakari
Pengfei
P
Meng
Hiroshi
H
Tanaka
D048868:Adaptor Proteins, Signal Transducing; D002478:Cells, Cultured; D018946:Chemokine CCL5 / Q000378:metabolism; D054357:Chemokine CXCL10 / Q000378:metabolism; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000072640:Interferon-Induced Helicase, IFIH1; D016899:Interferon-beta / Q000235:genetics / Q000378:metabolism; D008024:Ligands; D050527:Mesangial Cells; D011070:Poly I-C / Q000494:pharmacology; D034622:RNA Interference; D016601:RNA-Binding Proteins; D011971:Receptors, Immunologic; D015398:Signal Transduction / Q000187:drug effects; D051196:Toll-Like Receptor 3 / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; C483024:CCL5 protein, human; C114753:CXCL10 protein, human; D018946:Chemokine CCL5; D054357:Chemokine CXCL10; C484290:IFIT1 protein, human; D008024:Ligands; D016601:RNA-Binding Proteins; D011971:Receptors, Immunologic; D051196:Toll-Like Receptor 3; D014157:Transcription Factors; D016899:Interferon-beta; C452820:RIGI protein, human; C452815:IFIH1 protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases; D000072640:Interferon-Induced Helicase, IFIH1; D011070:Poly I-C