Roquin-2 promotes ubiquitin-mediated degradation of ASK1 to regulate stress responses.
Apoptosis signal-regulating kinase 1 (ASK1, also known as MAP3K5) mediates reactive oxygen species (ROS)-induced cell death. When activated by ROS, ASK1 ultimately becomes ubiquitinated and degraded by the proteasome, a process that is antagonized by the ubiquitin-specific protease USP9X. Using a functional siRNA (small interfering RNA) screen in HeLa cells, we identified Roquin-2 (also called RC3H2) as an E3 ubiquitin ligase required for ROS-induced ubiquitination and degradation of ASK1. In cells treated with H2O2, knockdown of Roquin-2 promoted sustained activation of ASK1 and the downstream stress-responsive kinases JNK (c-Jun amino-terminal kinase) and p38 MAPK (mitogen-activated protein kinase), and led to cell death. The nematode Caenorhabditis elegans produces ROS as a defense mechanism in response to bacterial infection. In C. elegans, mutation of the gene encoding the Roquin-2 ortholog RLE-1 promoted accumulation of the activated form of the ASK1 ortholog NSY-1 and conferred resistance to infection by the bacteria Pseudomonas aeruginosa. Thus, these data suggest that degradation of ASK1 mediated by Roquin-2 is an evolutionarily conserved mechanism required for the appropriate regulation of stress responses, including pathogen resistance and cell death.
1Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Takeshi
T
Maruyama
Toshihiro
T
Araki
Yosuke
Y
Kawarazaki
Isao
I
Naguro
Susanne
S
Heynen
Pedro
P
Aza-Blanc
Ze'ev
Z
Ronai
Atsushi
A
Matsuzawa
Hidenori
H
Ichijo
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000382:microbiology; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D004789:Enzyme Activation; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D048848:MAP Kinase Kinase Kinase 5 / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018384:Oxidative Stress; D059748:Proteolysis; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D012097:Repressor Proteins / Q000502:physiology*; D025801:Ubiquitin / Q000378:metabolism*; D054875:Ubiquitination
C000591671:RC3H2 protein, human; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D012097:Repressor Proteins; D025801:Ubiquitin; D006861:Hydrogen Peroxide; D020928:Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; C482858:MAP3K5 protein, human