scholarly journals Autophagic feedback-mediated degradation of IKKα requires CHK1- and p300/CBP-dependent acetylation of p53

2020 ◽  
Vol 133 (22) ◽  
pp. jcs246868
Author(s):  
Xiuduan Xu ◽  
Chongchong Zhang ◽  
Huan Xu ◽  
Lin Wu ◽  
Meiru Hu ◽  
...  
Keyword(s):  
Complex Formation ◽  
Feedback Loop ◽  
Hepatoma Cell ◽  
Critical Role ◽  
Human Hepatoma Cells ◽  
Catalytic Subunits ◽  
Selective Autophagy ◽  
Iκb Kinase ◽  
Ikk Complex ◽  
Autophagic Degradation

ABSTRACTIn our previous report, we demonstrated that one of the catalytic subunits of the IκB kinase (IKK) complex, IKKα (encoded by CHUK), performs an NF-κB-independent cytoprotective role in human hepatoma cells under the treatment of the anti-tumor therapeutic reagent arsenite. IKKα triggers its own degradation, as a feedback loop, by activating p53-dependent autophagy, and therefore contributes substantially to hepatoma cell apoptosis induced by arsenite. Interestingly, IKKα is unable to interact with p53 directly but plays a critical role in mediating p53 phosphorylation (at Ser15) by promoting CHK1 activation and CHK1–p53 complex formation. In the current study, we found that p53 acetylation (at Lys373 and/or Lys382) was also critical for the induction of autophagy and the autophagic degradation of IKKα during the arsenite response. Furthermore, IKKα was involved in p53 acetylation through interaction with the acetyltransferases for p53, p300 (also known as EP300) and CBP (also known as CREBBP) (collectively p300/CBP), inducing CHK1-dependent p300/CBP activation and promoting p300–p53 or CBP–p53 complex formation. Therefore, taken together with the previous report, we conclude that both IKKα- and CHK1-dependent p53 phosphorylation and acetylation contribute to mediating selective autophagy feedback degradation of IKKα during the arsenite-induced proapoptotic responses.

scholarly journals Annexin-A1 SUMOylation regulates microglial polarization after cerebral ischemia by modulating IKKα stability via selective autophagy

2021 ◽  
Vol 7 (4) ◽  
pp. eabc5539
Author(s):  
Xing Li ◽  
Qian Xia ◽  
Meng Mao ◽  
Huijuan Zhou ◽  
Lu Zheng ◽  
...  
Keyword(s):  
Cerebral Ischemia ◽  
Underlying Mechanism ◽  
Nuclear Factor Κb ◽  
Annexin A1 ◽  
Selective Autophagy ◽  
Microglial Polarization ◽  
Proinflammatory Mediators ◽  
Therapeutic Benefits ◽  
Iκb Kinase ◽  
Ikk Complex

Annexin-A1 (ANXA1) has recently been proposed to play a role in microglial activation after brain ischemia, but the underlying mechanism remains poorly understood. Here, we demonstrated that ANXA1 is modified by SUMOylation, and SUMOylated ANXA1 could promote the beneficial phenotype polarization of microglia. Mechanistically, SUMOylated ANXA1 suppressed nuclear factor κB activation and the production of proinflammatory mediators. Further study revealed that SUMOylated ANXA1 targeted the IκB kinase (IKK) complex and selectively enhanced IKKα degradation. Simultaneously, we detected that SUMOylated ANXA1 facilitated the interaction between IKKα and NBR1 to promote IKKα degradation through selective autophagy. Further work revealed that the overexpression of SUMOylated ANXA1 in microglia/macrophages resulted in marked improvement in neurological function in a mouse model of cerebral ischemia. Collectively, our study demonstrates a previously unidentified mechanism whereby SUMOylated ANXA1 regulates microglial polarization and strongly indicates that up-regulation of ANXA1 SUMOylation in microglia may provide therapeutic benefits for cerebral ischemia.

scholarly journals The IKKβ Subunit of IκB Kinase (IKK) is Essential for Nuclear Factor κB Activation and Prevention of Apoptosis

1999 ◽  
Vol 189 (11) ◽  
pp. 1839-1845 ◽  
Author(s):  
Zhi-Wei Li ◽  
Wenming Chu ◽  
Yinling Hu ◽  
Mireille Delhase ◽  
Tom Deerinck ◽  
...  
Keyword(s):  
Interleukin 1 ◽  
Nuclear Factor Κb ◽  
Regulatory Subunit ◽  
Nuclear Factor ◽  
Catalytic Subunits ◽  
Iκb Kinase ◽  
Ikk Complex ◽  
Factor Α ◽  
Necrosis Factor

The IκB kinase (IKK) complex is composed of three subunits, IKKα, IKKβ, and IKKγ (NEMO). While IKKα and IKKβ are highly similar catalytic subunits, both capable of IκB phosphorylation in vitro, IKKγ is a regulatory subunit. Previous biochemical and genetic analyses have indicated that despite their similar structures and in vitro kinase activities, IKKα and IKKβ have distinct functions. Surprisingly, disruption of the Ikkα locus did not abolish activation of IKK by proinflammatory stimuli and resulted in only a small decrease in nuclear factor (NF)-κB activation. Now we describe the pathophysiological consequence of disruption of the Ikkβ locus. IKKβ-deficient mice die at mid-gestation from uncontrolled liver apoptosis, a phenotype that is remarkably similar to that of mice deficient in both the RelA (p65) and NF-κB1 (p50/p105) subunits of NF-κB. Accordingly, IKKβ-deficient cells are defective in activation of IKK and NF-κB in response to either tumor necrosis factor α or interleukin 1. Thus IKKβ, but not IKKα, plays the major role in IKK activation and induction of NF-κB activity. In the absence of IKKβ, IKKα is unresponsive to IKK activators.

scholarly journals Tetrameric Oligomerization of IκB Kinase γ (IKKγ) Is Obligatory for IKK Complex Activity and NF-κB Activation

2003 ◽  
Vol 23 (6) ◽  
pp. 2029-2041 ◽  
Author(s):  
Sebastian Tegethoff ◽  
Joachim Behlke ◽  
Claus Scheidereit
Keyword(s):  
Kinase Activity ◽  
Coiled Coil ◽  
Complex Activity ◽  
Catalytic Subunits ◽  
Iκb Kinase ◽  
293 Cells ◽  
Activation Of Transcription ◽  
Ikk Complex ◽  
Spatial Positioning ◽  
Oligomerization Domain

ABSTRACT The IκB kinase (IKK) complex mediates activation of transcription factor NF-κB by phosphorylation of IκB proteins. Its catalytic subunits, IKKα and IKKβ, require association with the regulatory IKKγ (NEMO) component to gain full basal and inducible kinase activity. However, the oligomeric composition of the IKK complex and its regulation by IKKγ are poorly understood. We show here that IKKγ predominantly forms tetramers and interacts with IKKα or IKKβ in this state. We propose that tetramerization is accomplished by a prerequisite dimerization through a C-terminal coiled-coil minimal oligomerization domain (MOD). This is followed by dimerization of the dimers with their N-terminal sequences. Tetrameric IKKγ sequesters four kinase molecules, yielding a γ4(α/β)4 stoichiometry. Deletion of the MOD leads to loss of tetramerization and of phosphorylation of IKKβ and IKKγ, although the kinase can still interact with the resultant IKKγ monomers and dimers. Likewise, MOD-mediated IKKγ tetramerization is required to enhance IKKβ kinase activity when overexpressed in 293 cells and to reconstitute a lipopolysaccharide-responsive IKK complex in pre-B cells. These data thus suggest that IKKγ tetramerization enforces a spatial positioning of two kinase dimers to facilitate transautophosphorylation and activation.

scholarly journals Phosphorylation of the selective autophagy receptor TAX1BP1 by canonical and noncanonical IκB kinases promotes its lysosomal localization and clearance of MAVS aggregates

2021 ◽  
Author(s):  
Young Bong Choi ◽  
Jiawen Zhang ◽  
Mai Tram Vo ◽  
Jesse White ◽  
Chaoxia He ◽  
...  
Keyword(s):  
Virus Infection ◽  
Rna Virus ◽  
Critical Role ◽  
Selective Autophagy ◽  
The Core ◽  
Data Support ◽  
Iκb Kinase

TAX1BP1 is a selective autophagy receptor which inhibits NF-κB and RIG-I-like receptor (RLR) signaling to prevent excessive inflammation and maintain homeostasis. Selective autophagy receptors such as p62/SQSTM1 and OPTN are phosphorylated by the noncanonical IκB kinase TBK1 to stimulate their selective autophagy function. However, it is unknown if TAX1BP1 is regulated by TBK1 or other kinases under basal conditions or during RNA virus infection. Here, we found that the noncanonical IκB kinases TBK1 and IKKi phosphorylate TAX1BP1 to regulate its basal turnover, whereas the canonical IκB kinase IKKα and the core autophagy factor ATG9 play essential roles in RNA virus-mediated TAX1BP1 autophagosomal degradation. TAX1BP1 phosphorylation by canonical and noncanonical IκB kinases promotes its localization to lysosomes resulting in its degradation. Furthermore, TAX1BP1 plays a critical role in the clearance of MAVS aggregates, and phosphorylation of TAX1BP1 augments its MAVS aggrephagy function. Together, our data support a model whereby IκB kinases license TAX1BP1 selective autophagy function to inhibit MAVS and RLR signaling.

scholarly journals Oxidative Stress Transiently Decreases the IKK Complex (IKKα, β, and γ), an Upstream Component of NF-κB Signaling, after Transient Focal Cerebral Ischemia in Mice

2005 ◽  
Vol 25 (10) ◽  
pp. 1301-1311 ◽  
Author(s):  
Yun S Song ◽  
Yong-Sun Lee ◽  
Pak H Chan
Keyword(s):  
Cerebral Ischemia ◽  
Focal Cerebral Ischemia ◽  
Nuclear Factor Κb ◽  
Nuclear Factor ◽  
Dna Array ◽  
Wild Type ◽  
Iκb Kinase ◽  
Transient Focal Cerebral Ischemia ◽  
Ikk Complex ◽  
In The Wild

Nuclear factor-κB (NF-κB) has a central role in coordinating the expression of a wide variety of genes that control cerebral ischemia. Although there has been intense research on NF-κB, its mechanisms in the ischemic brain have not been clearly elucidated. We investigated the temporal profile of NF-κB-related genes using a complementary DNA array method in wild-type mice and human copper/zinc-superoxide dismutase transgenic (SOD1 Tg) mice that had low-level reactive oxygen species (ROS) by scavenging superoxide. Our DNA array showed that IκB kinase (IKK) complex (IKKα, β, and γ) mRNA in the wild-type mice was decreased as early as 1 h after reperfusion, after 30 mins of transient focal cerebral ischemia (tFCI). In contrast, tFCI in the SOD1 Tg mice caused an increase in the IKK complex. The IKK complex protein levels were also drastically decreased at 1 h in the wild-type mice, but did not change in the SOD1 Tg mice throughout the 7 days. Electrophoretic mobility shift assay revealed activation of NF-κB DNA binding after tFCI in the wild-type mice. Nuclear factor-κB activation occurred at the same time, as did the phosphorylation and degradation of the inhibitory protein κBα. However, SOD1 prevented NF-κB activation, and phosphorylation and degradation of IκBα after tFCI. Superoxide production and ubiquitinated protein in the SOD1 Tg mice were also lower than in the wild-type mice after tFCI. These results suggest that ROS are implicated in transient downregulation of IKKα, β, and γ in cerebral ischemia.

The vitamin K–dependent γ-glutamyl carboxylase gene contains a TATA-less promoter with a novel upstream regulatory element

Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1333-1339 ◽  
Author(s):  
Elizabeth E. Romero ◽  
Umaima Marvi ◽  
Zachary E. Niman ◽  
David A. Roth
Keyword(s):  
Blood Coagulation ◽  
Dna Sequence ◽  
Vitamin K ◽  
Nuclear Protein ◽  
Regulatory Element ◽  
Hepatoma Cell ◽  
Critical Role ◽  
Developmental Expression ◽  
Regulatory Sequences ◽  
Developmentally Regulated

Abstract The expression of the vitamin K–dependent γ-glutamyl carboxylase gene in liver is developmentally regulated. Since the gene product catalyzes an essential post-translational modification of the vitamin K–dependent blood coagulation proteins, the regulation of carboxylase expression is critical for hemostasis. We analyzed the activity of the rat carboxylase gene 5′-regulatory DNA sequences in rat hepatoma cell lines at different states of differentiation. These studies demonstrated that the 2.6-kb 5′-flanking sequence has differentiation-dependent transcriptional activity. Transient gene expression assays, examining the effects of nested deletions and site-directed mutagenesis of putative regulatory sequences, together with electrophoretic mobility shift assays (EMSAs) were used to identify sequences critical for the developmentally regulated transcription of the rat carboxylase gene. We identified a DNA sequence (–76 to –65; GTTCCGGCCTTC) not known to bind to transcription factors, yet which functions as an upstream promoter element. In vivo genomic DNA footprinting confirms the presence of nuclear protein–DNA interactions at this site in the endogenous carboxylase gene in differentiated hepatoma cells. Therefore, this DNA sequence has specific nuclear protein–binding activity and functional properties consistent with a regulatory element that plays a critical role in the developmental expression of the carboxylase gene, and hence the regulation of vitamin K–dependent blood coagulation protein synthesis.

scholarly journals FKBP51 Promotes Assembly of the Hsp90 Chaperone Complex and Regulates Androgen Receptor Signaling in Prostate Cancer Cells

2010 ◽  
Vol 30 (5) ◽  
pp. 1243-1253 ◽  
Author(s):  
Li Ni ◽  
Chun-Song Yang ◽  
Daniel Gioeli ◽  
Henry Frierson ◽  
David O. Toft ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cancer Cells ◽  
Cancer Progression ◽  
Feedback Loop ◽  
Critical Role ◽  
Prostate Cancer Cells ◽  
Androgen Receptor Signaling ◽  
Hsp90 Chaperone ◽  
Chaperone Complex ◽  
Androgen Binding

ABSTRACT Prostate cancer progression to the androgen-independent (AI) state involves acquisition of pathways that allow tumor growth under low-androgen conditions. We hypothesized that expression of molecular chaperones that modulate androgen binding to AR might be altered in prostate cancer and contribute to progression to the AI state. Here, we report that the Hsp90 cochaperone FKBP51 is upregulated in LAPC-4 AI tumors grown in castrated mice and describe a molecular mechanism by which FKBP51 regulates AR activity. Using recombinant proteins, we show that FKBP51 stimulates recruitment of the cochaperone p23 to the ATP-bound form of Hsp90, forming an FKBP51-Hsp90-p23 superchaperone complex. In cells, FKBP51 expression promotes superchaperone complex association with AR and increases the number of AR molecules that undergo androgen binding. FKBP51 stimulates androgen-dependent transcription and cell growth, and FKBP51 is part of a positive feedback loop that is regulated by AR and androgen. Finally, depleting FKBP51 levels by short hairpin RNA reduces the transcript levels of genes regulated by AR and androgen. Because the superchaperone complex plays a critical role in determining the ligand-binding competence and transcription function of AR, it provides an attractive target for inhibiting AR activity in prostate cancer cells.

Abstract 343: Vascular Inflammation in Two Rat Models of Arterial Hypertension is Promoted by Coagulation FXI

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Jeremy Lagrange ◽  
Sabine Kossmann ◽  
Andreas Daiber ◽  
Matthias Oelze ◽  
Brett Monia ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Arterial Hypertension ◽  
Feedback Loop ◽  
Thrombin Generation ◽  
Vascular Reactivity ◽  
Platelet Rich Plasma ◽  
Vascular Dysfunction ◽  
Vascular Inflammation ◽  
Critical Role ◽  
Experimental Hypertension

Backgroud: Interactions of platelets, leukocytes and the vessel wall play pivotal roles in activating coagulation and precipitating thrombosis. We were recently able to uncover an angiotensin II (ATII) driven factor XI (FXI)-thrombin amplification loop leading to vascular injury in experimental hypertension in mice. Objective: We wanted was to explore the role of thrombin-FXI feedback loop in different models of arterial hypertension in rats. Methods: ATII treated wistar rats (1mg·kg -1 ·d -1 for 7 days using osmotic minipumps) and 5/6 nephrectomized were used for this study. During 2 weeks rats were treated with a FXI antisense oligonucleotide (ASO) (1 week after nephrectomy or 2 weeks before ATII pump implantation, respectively). Blood pressure was recorded with tail cuff measurement. Fluorescence oxidative microtopography was used to evaluate vascular ROS production. Vascular reactivity was assessed in isolated aortic segment. Calibrated automated thrombography was used to measure thrombin generation. Results: In ATII infused rats as well as 5/6 nephrectomized rats vascular dysfunction related to hypertension was attenuated when rats were treated with FXI ASO. Hypertension induced VCAM-1 expression was normalize with inhibition of FXI. ROS formation was normalized in ATII infused rats as well as 5/6 nephrectomized treated with FXI ASO. Thrombin generation in platelet rich plasma from 5/6 nephrectomized rats was completely abolished when FXI was inhibited. Finally the overall blood pressure increase was abrogated by FXI ASO treatment in 5/6 nephrectomized rats. Conclusion: FXI plays a critical role in a FXI-thrombin feedback loop in hypertension. This pathway is relevant in mice and rats and we were able to very recently obtain the first conclusive results in humans. FXI could be a novel therapeutic target to interrupt this heterotypic cellular coagulation-inflammatory circuit.

scholarly journals Thioredoxin 2 Negatively Regulates Innate Immunity to RNA Viruses by Disrupting the Assembly of the Virus-Induced Signaling Adaptor Complex

2020 ◽  
Vol 94 (7) ◽  
Author(s):  
Dan Li ◽  
Wenping Yang ◽  
Yi Ru ◽  
Jingjing Ren ◽  
Xiangtao Liu ◽  
...  
Keyword(s):  
Complex Formation ◽  
Rna Viruses ◽  
Critical Role ◽  
Type I Interferons ◽  
Type I ◽  
Host Proteins ◽  
Innate Antiviral Response ◽  
Thioredoxin 2

ABSTRACT The virus-induced signaling adaptor (VISA) complex plays a critical role in the innate immune response to RNA viruses. However, the mechanism of VISA complex formation remains unclear. Here, we demonstrate that thioredoxin 2 (TRX2) interacts with VISA at mitochondria both in vivo and in vitro. Knockdown and knockout of TRX2 enhanced the formation of the VISA-associated complex, as well as virus-triggered activation of interferon regulatory factor 3 (IRF3) and transcription of the interferon beta 1 (IFNB1) gene. TRX2 inhibits the formation of VISA aggregates by repressing reactive oxygen species (ROS) production, thereby disrupting the assembly of the VISA complex. Furthermore, our data suggest that the C93 residue of TRX2 is essential for inhibition of VISA aggregation, whereas the C283 residue of VISA is required for VISA aggregation. Collectively, these findings uncover a novel mechanism of TRX2 that negatively regulates VISA complex formation. IMPORTANCE The VISA-associated complex plays pivotal roles in inducing type I interferons (IFNs) and eliciting the innate antiviral response. Many host proteins are identified as VISA-associated-complex proteins, but how VISA complex formation is regulated by host proteins remains enigmatic. We identified the TRX2 protein as an important regulator of VISA complex formation. Knockout of TRX2 increases virus- or poly(I·C)-triggered induction of type I IFNs at the VISA level. Mechanistically, TRX2 inhibits the production of ROS at its C93 site, which impairs VISA aggregates at its C283 site, and subsequently impedes the assembly of the VISA complex. Our findings suggest that TRX2 plays an important role in the regulation of VISA complex assembly.

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