A20 Ameliorates Intracerebral Hemorrhage–Induced Inflammatory Injury by Regulating TRAF6 Polyubiquitination

Abstract

Reducing excessive inflammation is beneficial for the recovery from intracerebral hemorrhage (ICH). Here, the roles and mechanisms of A20 (TNFAIP3), an important endogenous anti-inflammatory factor, are examined in ICH. A20 expression in the PBMCs of ICH patients and an ICH mouse model was detected, and the correlation between A20 expression and neurologic deficits was analyzed. A20 expression was increased in PBMCs and was negatively related to the modified Rankin Scale score. A20 expression was also increased in mouse perihematomal tissues. A20−/− and A20-overexpressing mice were generated to further analyze A20 function. Compared with wild-type (WT) mice, A20−/− and A20-overexpressing mice showed significant increases and decreases, respectively, in hematoma volume, neurologic deficit score, mortality, neuronal degeneration, and proinflammatory factors. Moreover, WT-A20−/− parabiosis was established to explore the role of A20 in peripheral blood in ICH injury. ICH-induced damage, including brain edema, neurologic deficit score, proinflammatory factors, and neuronal apoptosis, was reduced in A20−/− parabionts compared with A20−/− mice. Finally, the interactions between TRAF6 and Ubc13 and UbcH5c were increased in A20−/− mice compared with WT mice; the opposite occurred in A20-overexpressing mice. Enhanced IκBα degradation and NF-κB activation were observed in A20−/− mice, but the results were reversed in A20-overexpressing mice. These results suggested that A20 is involved in regulating ICH-induced inflammatory injury in both the central and peripheral system and that A20 reduces ICH-induced inflammation by regulating TRAF6 polyubiquitination. Targeting A20 may thus be a promising therapeutic strategy for ICH.

A Computational Approach for Mapping Heme Biology in the Context of Hemolytic Disorders

“…However, in our heme knowledge graph the connections between IRAKs, TRAF6, and TAB proteins were missing ( Figure 4A). By taking a closer look at these effectors in the context of heme, we found various information for example TRAF6 indicating both a direct and indirect link to heme-induced signaling via TLRs (Hama et al, 2012;IJssennagger et al, 2012;Park et al, 2014;Huang et al, 2015;Meng et al, 2017). In contrast, other effector molecules such as IRAK and TAB proteins (Figure 4) were not described in heme signaling so far.…”

Prdx1 Reduces Intracerebral Hemorrhage-Induced Brain Injury via Targeting Inflammation- and Apoptosis-Related mRNA Stability

“…Quantitative Real-Time PCR Using our previously described method to isolate total RNA and perform qRT-PCR (Meng et al, 2017), tissue and cellular RNA were extracted using TRIzol (Invitrogen, Carlsbad, CA) and RNA was reverse transcribed into cDNA (Takara, Dalian, China). Quantitative RT-PCR was performed on an ABI PCR instrument (ABI, CA, United States) using iQ SYBR Green reagent.…”

“…Following methods described in the literature (Meng et al, 2017), the number of dead rats was counted once every hour after ICH. To calculate the survival rate, the following equation was used: (number of ICH rats per group -number of dead rats per group)/number of ICH rats per group.…”

“…According to our previous methods (Meng et al, 2017), the rats were sacrificed at 3 d after ICH, and brain tissues were taken and frozen at −20 • C for 30 min. Coronal sections of the brain were made with a thickness of 1mm.…”

Poly(I:C) preconditioning ameliorates cognitive dysfunction after cerebral I/R injury by inhibiting TRAF6 signaling

“…Recent studies have shown that TRAF6 plays important roles in regulating host immunity, embryonic development, tissue homeostasis, and neurodegenerative disease [18,19]. Our previous study revealed that TRAF6 polyubiquitination may participate in secondary inflammatory injury in a mouse model of intracerebral hemorrhage [20]. Meanwhile, TRAF6 expression has been reported to be upregulated in the peripheral blood of ischemic stroke patients, as well as in neurons from a rat model of cerebral I/R [21].…”