Alix and ALG-2 make a link between endosomes and neuronal death

2009 ◽  
Vol 37 (1) ◽  
pp. 200-203 ◽  
Author(s):  
Anne-Laure Mahul-Mellier ◽  
Flavie Strappazzon ◽  
Christine Chatellard-Causse ◽  
Béatrice Blot ◽  
David Béal ◽  
...  
Keyword(s):  
Neuronal Death ◽  
Calcium Binding ◽  
Death Receptor ◽  
Adaptor Protein ◽  
Endosomal Trafficking ◽  
Interacting Protein ◽  
Linked Gene ◽  
Endosomal Sorting ◽  
Factor Α ◽  
Necrosis Factor

Alix [ALG-2 (apoptosis-linked gene 2)-interacting protein X] is a ubiquitinous adaptor protein first described for its capacity to bind to the calcium-binding protein, ALG-2. Alix regulates neuronal death in ways involving interactions with ALG-2 and with proteins of the ESCRT (endosomal sorting complex required for transport). Even though all Alix interactors characterized to date are involved in endosomal trafficking, the genuine function of the protein in this process remains unclear. We have demonstrated recently that Alix and ALG-2 form in the presence of calcium, a complex with apical caspases and with the endocytosed death receptor TNFR1 (tumour necrosis factor α receptor 1), thus suggesting a molecular coupling between endosomes and the cell death machinery.

scholarly journals Lipopolysaccharide induces neuroglia activation and NF-κB activation in cerebral cortex of adult mice

2019 ◽  
Vol 35 (1) ◽  
Author(s):  
Ju-Bin Kang ◽  
Dong-Ju Park ◽  
Murad-Ali Shah ◽  
Myeong-Ok Kim ◽  
Phil-Ok Koh
Keyword(s):  
Oxidative Stress ◽  
Cerebral Cortex ◽  
Calcium Binding ◽  
Inflammatory Responses ◽  
Inflammatory Factors ◽  
Adult Mice ◽  
Tnf Α ◽  
Factor Α ◽  
And Oxidative Stress ◽  
Necrosis Factor

Abstract Lipopolysaccharide (LPS) acts as an endotoxin, releases inflammatory cytokines, and promotes an inflammatory response in various tissues. This study investigated whether LPS modulates neuroglia activation and nuclear factor kappa B (NF-κB)-mediated inflammatory factors in the cerebral cortex. Adult male mice were divided into control animals and LPS-treated animals. The mice received LPS (250 μg/kg) or vehicle via an intraperitoneal injection for 5 days. We confirmed a reduction of body weight in LPS-treated animals and observed severe histopathological changes in the cerebral cortex. Moreover, we elucidated increases of reactive oxygen species and oxidative stress levels in LPS-treated animals. LPS administration led to increases of ionized calcium-binding adaptor molecule-1 (Iba-1) and glial fibrillary acidic protein (GFAP) expression. Iba-1 and GFAP are well accepted as markers of activated microglia and astrocytes, respectively. Moreover, LPS exposure induced increases of NF-κB and pro-inflammatory factors, such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Increases of these inflammatory mediators by LPS exposure indicate that LPS leads to inflammatory responses and tissue damage. These results demonstrated that LPS activates neuroglial cells and increases NF-κB-mediated inflammatory factors in the cerebral cortex. Thus, these findings suggest that LPS induces neurotoxicity by increasing oxidative stress and activating neuroglia and inflammatory factors in the cerebral cortex.

The ESCRT pathway and HIV-1 budding

2009 ◽  
Vol 37 (1) ◽  
pp. 181-184 ◽  
Author(s):  
Yoshiko Usami ◽  
Sergei Popov ◽  
Elena Popova ◽  
Michio Inoue ◽  
Winfried Weissenhorn ◽  
...  
Keyword(s):  
Susceptibility Gene ◽  
Multivesicular Body ◽  
Intramolecular Interactions ◽  
Transport Pathway ◽  
Interacting Protein ◽  
Linked Gene ◽  
Endosomal Sorting ◽  
Binding Partner ◽  
Protein X ◽  
Hiv 1

HIV-1 Gag engages components of the ESCRT (endosomal sorting complex required for transport) pathway via so-called L (late-assembly) domains to promote virus budding. Specifically, the PTAP (Pro-Thr-Ala-Pro)-type primary L domain of HIV-1 recruits ESCRT-I by binding to Tsg101 (tumour susceptibility gene 101), and an auxiliary LYPXnL (Leu-Tyr-Pro-Xaan-Leu)-type L domain recruits the ESCRT-III-binding partner Alix [ALG-2 (apoptosis-linked gene 2)-interacting protein X]. The structurally related CHMPs (charged multivesicular body proteins), which form ESCRT-III, are kept in an inactive state through intramolecular interactions, and become potent inhibitors of HIV-1 budding upon removal of an autoinhibitory region. In the absence of the primary L domain, HIV-1 budding is strongly impaired, but can be efficiently rescued through the overexpression of Alix. This effect of Alix depends on its ability to interact with CHMP4, suggesting that it is the recruitment of CHMPs that ultimately drives virus release. Surprisingly, HIV-1 budding defects can also be efficiently corrected by overexpressing Nedd (neural-precursor-cell-expressed developmentally down-regulated) 4-2s, a member of a family of ubiquitin ligases previously implicated in the function of PPXY (Pro-Pro-Xaa-Tyr)-type L domains, which are absent from HIV-1. At least under certain circumstances, Nedd4-2s stimulates the activity of PTAP-type L domains, raising the possibility that the ubiquitin ligase regulates the activity of ESCRT-I.

scholarly journals TRAF2 inhibits TRAIL- and CD95L-induced apoptosis and necroptosis

2014 ◽  
Vol 5 (10) ◽  
pp. e1444-e1444 ◽  
Author(s):  
I Karl ◽  
M Jossberger-Werner ◽  
N Schmidt ◽  
S Horn ◽  
M Goebeler ◽  
...  
Keyword(s):  
Cell Death ◽  
Hela Cells ◽  
Protein Complexes ◽  
Combined Treatment ◽  
Death Receptor ◽  
Adaptor Protein ◽  
Negative Regulator ◽  
Interacting Protein ◽  
Induced Apoptosis ◽  
The Impact

Abstract The relevance of the adaptor protein TNF receptor-associated factor 2 (TRAF2) for signal transduction of the death receptor tumour necrosis factor receptor1 (TNFR1) is well-established. The role of TRAF2 for signalling by CD95 and the TNF-related apoptosis inducing ligand (TRAIL) DRs, however, is only poorly understood. Here, we observed that knockdown (KD) of TRAF2 sensitised keratinocytes for TRAIL- and CD95L-induced apoptosis. Interestingly, while cell death was fully blocked by the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD-fmk) in control cells, TRAF2-depleted keratinocytes were only partly rescued from TRAIL- and CD95L-induced cell death. In line with the idea that the only partially protective effect of zVAD-fmk on TRAIL- and CD95L-treated TRAF2-depleted keratinocytes is due to the induction of necroptosis, combined treatment with zVAD-fmk and the receptor interacting protein 1 (RIP1) inhibitor necrostatin-1 fully rescued these cells. To better understand the impact of TRAF2 levels on RIP1- and RIP3-dependent necroptosis and RIP3-independent apoptosis, we performed experiments in HeLa cells that lack endogenous RIP3 and HeLa cells stably transfected with RIP3. HeLa cells, in which necroptosis has no role, were markedly sensitised to TRAIL-induced caspase-dependent apoptosis by TRAF2 KD. In RIP3-expressing HeLa transfectants, however, KD of TRAF2 also strongly sensitised for TRAIL-induced necroptosis. Noteworthy, priming of keratinocytes with soluble TWEAK, which depletes the cytosolic pool of TRAF2-containing protein complexes, resulted in strong sensitisation for TRAIL-induced necroptosis but had only a very limited effect on TRAIL-induced apoptosis. The necroptotic TRAIL response was not dependent on endogenously produced TNF and TNFR signalling, since blocking TNF by TNFR2-Fc or anti-TNFα had no effect on necroptosis induction. Taken together, we identified TRAF2 not only as a negative regulator of DR-induced apoptosis but in particular also as an antagonist of TRAIL- and CD95L-induced necroptosis.

scholarly journals BNIP3 decreases the LPS-induced inflammation and apoptosis of chondrocytes by promoting the development of autophagy

2020 ◽  
Author(s):  
Zetao Ma ◽  
Deli Wang ◽  
Jian Weng ◽  
Sheng Zhang ◽  
Yuanshi Zhang
Keyword(s):  
Interleukin 1 ◽  
Interleukin 1 Beta ◽  
Related Protein ◽  
Interacting Protein ◽  
Tnf Α ◽  
Adenovirus E1b ◽  
Factor Α ◽  
Related Proteins ◽  
Necrosis Factor ◽  
Proinflammatory Factors

Abstract Background: Inflammation and apoptosis of chondrocytes are the pathological basis of osteoarthritis. Autophagy could alleviate the symptoms of inflammation and apoptosis. Previous study has shown that BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) can induce the occurrence and development of autophagy. However, it is unknown whether autophagy induced by BNIP3 can alleviate the inflammation and apoptosis of chondrocytes. Methods: We used the lentivirus to construct the overexpression BNIP3 chondrocytes. Next, the lipopolysaccharide (LPS) was used to stimulate these cells to simulate the physiological environment of osteoarthritis. After that, the enzyme-linked immunosorbent assays (ELISA) were performed to determine the levels of tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) and the flow cytometry was performed to detect the apoptosis rates of chondrocytes. At last, the expression of autophagy related proteins was detected with the western blotting. Results: The expression of BNIP3 was suppressed after treatment with LPS. However, overexpression of BNIP3 inhibited the secretion of proinflammatory factors (TNF-α, IL-1β and IL-6) and decreased the apoptosis of chondrocytes. Furthermore, overexpression of BNIP3 led to the upregulation of autophagy related proteins expression including little computer 3 (LC3), autophagy-related protein 7 (ATG7) and Beclin-1. Application of autophagy inhibitor recovered the expression of proinflammatory factors and apoptosis rates of chondrocytes. Conclusions: BNIP3 decreased the LPS induced inflammation and apoptosis of chondrocytes by activating the autophagy.

scholarly journals Tumour necrosis factor receptor-associated factors: interacting protein with forkhead-associated domain inhibition decreases inflammatory cell infiltration and cardiac remodelling after acute myocardial infarction

2020 ◽  
Vol 31 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Yicheng Jiang ◽  
Xue Li ◽  
Hai Xu ◽  
Yang Gu ◽  
Feiya Shi ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Mouse Model ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Cardiac Remodelling ◽  
Tumour Necrosis Factor Receptor ◽  
Tumour Necrosis Factor Α ◽  
Interacting Protein ◽  
Factor Α ◽  
Necrosis Factor

Abstract OBJECTIVES Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide. Post-AMI cardiac remodelling is closely related to the prognosis of AMI. The excess inflammatory responses could promote cardiac remodelling. Tumour necrosis factor receptor-associated factor-interacting protein with forkhead-associated domain (TIFA) has been identified as a nuclear factor (NF)-κB activator, which plays a key role in the activation of the NF-κB signalling pathway. The goal of this research was to investigate the expression and the underlying mechanism of TIFA in an AMI mouse model. METHODS The AMI mouse model was induced by ligation of the left coronary artery. TIFA and NF-κB knockdown were established by lentivirus transduction. The expression levels of associated proteins were analysed by a western blot or an enzyme-linked immunosorbent assay. Histological characteristics were evaluated by haematoxylin–eosin staining. RESULTS The TIFA level was elevated in our AMI mouse model. The production of interleukin-1β and tumour necrosis factor-α increased markedly in the mice with AMI. TIFA knockdown inhibited the infiltration of inflammatory cells, production of pro-inflammatory mediators (interleukin-1β and tumour necrosis factor-α), NF-κB activation and cardiac remodelling (matrix metallopeptidase 9) post-AMI. In addition, NF-κB knockdown could also alleviate cardiac remodelling after AMI. CONCLUSIONS The preceding results indicated that TIFA inhibition could ameliorate cardiac remodelling after AMI partly through inactivation of NF-κB. This study provides insights into further research of cardiac remodelling and AMI from bench to clinic.

The CHMP4b- and Src-docking sites in the Bro1 domain are autoinhibited in the native state of Alix

2009 ◽  
Vol 418 (2) ◽  
pp. 277-284 ◽  
Author(s):  
Xi Zhou ◽  
Shujuan Pan ◽  
Le Sun ◽  
Joe Corvera ◽  
Yu-Chen Lee ◽  
...  
Keyword(s):  
Multivesicular Body ◽  
Human Embryonic Kidney ◽  
Native State ◽  
Interacting Protein ◽  
Body Protein ◽  
Linked Gene ◽  
Endosomal Sorting ◽  
Protein X ◽  
Membrane Bound ◽  
Docking Sites

The Bro1 domain of Alix [ALG-2 (apoptosis-linked gene 2)-interacting protein X], which plays important roles in endosomal sorting and multiple ESCRT (endosomal sorting complex required for transport)-linked processes, contains the docking sites for the ESCRT-III component CHMP4b (charged multivesicular body protein 4b) and the regulatory tyrosine kinase, Src. Although the structural bases for these docking sites have been defined by crystallography studies, it has not been determined whether these sites are available in the native state of Alix. In the present study, we demonstrate that these two docking sites are unavailable in recombinant Alix under native conditions and that their availabilities can be induced by detergents. In HEK (human embryonic kidney)-293 cell lysates, these two docking sites are not available in cytosolic Alix, but are available in membrane-bound Alix. These findings show that the native state of Alix does not have a functional Bro1 domain and predict that Alix's involvement in endosomal sorting and other ESCRT-linked processes requires an activation step that relieves the autoinhibition of the Bro1 domain.

The mechanism of Ca2+-dependent recognition of Alix by ALG-2: insights from X-ray crystal structures

2009 ◽  
Vol 37 (1) ◽  
pp. 190-194 ◽  
Author(s):  
Hironori Suzuki ◽  
Masato Kawasaki ◽  
Tatsutoshi Inuzuka ◽  
Mayumi Okumura ◽  
Takeshi Kakiuchi ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Susceptibility Gene ◽  
Adaptor Protein ◽  
Side Chain ◽  
Interacting Protein ◽  
Linked Gene ◽  
X Ray ◽  
Ef Hand ◽  
Peptide Binding Site ◽  
Crystal Structural

Alix [ALG-2 (apoptosis-linked gene 2)-interacting protein X] was originally identified as a protein that interacts with ALG-2, a member of the penta-EF-hand Ca2+-binding protein family. ALG-2 binds to its C-terminal proline-rich region that contains four tandem repeats of PXY (where X represents an uncharged amino acid). Recent X-ray crystal structural analyses of the Ca2+-free and Ca2+-bound forms of ALG-2, as well as the complex with an Alix oligopeptide, have revealed a mechanism of Ca2+-dependent binding of ALG-2 to its target protein. Binding of Ca2+ to EF3 (third EF-hand) enables the side chain of Arg125, present in the loop connecting EF3 and EF4 (fourth EF-hand), to move sufficiently to make a primary hydrophobic pocket accessible to the critical PPYP (Pro-Pro-Tyr-Pro) motif in Alix, which partially overlaps with the GPP (Gly-Pro-Pro) motif for binding to Cep55 (centrosome protein of 55 kDa). The fact that ALG-2 forms a homodimer and each monomer has one peptide-binding site indicates the possibility that ALG-2 bridges two interacting proteins, including Alix and Tsg101 (tumour susceptibility gene 101), and functions as a Ca2+-dependent adaptor protein.

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