Abstract
Ubiquitination is an important posttranslational modification associated with essential cellular processes. Here we show that deletion of E3 ubiquitin ligase HECTD3 — germline or in hematopoietic compartment, including in Cd11c+ cells — causes severe disease and increased production of proinflammatory cytokines in a murine model of ulcerative colitis (UC). HECTD3 mRNA levels were found reduced in colonic tissues of patients with UC, which highlights a potential role for HECTD3 in regulating inflammatory responses in UC. We identified MyD88, a central adaptor in the TLR/IL-1R signaling and inflammatory response, as a target for HECTD3 ubiquitination. We demonstrate that HECTD3 ubiquitinates MyD88 through K27-linked Poly-Ub chains in a nondegradative manner. HECTD3-KO GM-CSF–bone marrow–derived cells treated with the TLR4 ligand LPS produced more proinflammatory cytokines, showed elevated phosphorylation of NF-κB and IRAK4, as well as increased association of MyD88 with IRAK4, demonstrating that HECTD3 controls MyD88/IRAK4/NF-κB axis. Inhibition of MyD88 activity rescued colitis severity in the HECTD3-KO mice, including the elevated proinflammatory cytokine production. Thus, our results establish MyD88 as a target for HECTD3 nondegradative polyubiquitination and restriction of innate immune colonic inflammation.
Authors
Shamima Islam, Shahnewaj Mannan, Ashley Zuniga, Upasana Parthasarathy, Valeriu B. Cismasiu, Leonardo Silvane, Sayan Chakraborty, Divya Priyanka Talada, Raghwendra Pratap Singh, Tomas Zelenka, Amreen Naveen, Sephra Chyanne Vickers, Michael G.M. Grant, Jonathan J. Cho, Theodore Drashansky, Alexander J. Kwiatkowski, Xintong Liu, Ross Tomaino, Olga A. Guryanova, Mariola J. Ferraro, Sang Yong Kim, Christian Jobin, Benjamin G. Keselowsky, Hongmin Li, Paulo C. Rodriguez, Martina Molgora, Amer A. Beg, Timothy I. Shaw, Zheng Ruan, Lixin Wan, Dorina Avram
Figure 8
Absence of HECTD3 causes increased MyD88-IRAK4 interaction and IRAK4 phosphorylation.
