RIOK3 interacts with caspase-10 and negatively regulates the NF-kappaB signaling pathway.
RIOK3 was initially characterized as a homolog of Aspergillus nidulans sudD and showed down-regulation at the invasive front of malignant melanomas, but the molecular mechanism remains elusive. Here, we report that overexpression of RIOK3 inhibits TNFalpha-induced NF-kappaB activation, but down-regulation of endogenous RIOK3 expression by siRNA potentiates it. A yeast two-hybrid experiment revealed that RIOK3 interacted with caspase-10, and further, a GST pull-down assay and endogenous coimmunoprecipitation validated the interaction. We subsequently showed that the interaction was mediated by the RIO domain of RIOK3 and each death effector domain of caspase-10. Interestingly, our data demonstrated that RIOK3 suppressed caspase-10-mediated NF-kappaB activation by competing RIP1 and NIK to bind to caspase-10. Importantly, the kinase activity of RIOK3 was confirmed to be relevant to NF-kappaB signaling. Taken together, our findings strongly suggest that RIOK3 negatively regulates NF-kappaB signaling pathway activated by TNFalpha dependent on its kinase activity and NF-kappaB signaling pathway activated by caspase-10 independent of its kinase activity.
Shan
Jingxuan
J
State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 220 Handan Road, 200433, Shanghai, China.
Wang
Pingzhang
P
Zhou
Juan
J
Wu
Donghua
D
Shi
Huili
H
Huo
Keke
K
D053455:Caspase 10 / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D015536:Down-Regulation; D005786:Gene Expression Regulation; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D020798:Two-Hybrid System Techniques
D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D008156:Luciferases; D017346:Protein Serine-Threonine Kinases; C534426:RIO kinase 3, human; D053455:Caspase 10