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APPL1 Is a Prognostic Biomarker and Correlated with Treg Cell Infiltration via Oxygen-Consuming Metabolism in Renal Clear Cell Carcinoma. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2023; 2023:5885203. [PMID: 36846720 PMCID: PMC9957629 DOI: 10.1155/2023/5885203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 11/07/2022] [Accepted: 11/24/2022] [Indexed: 02/19/2023]
Abstract
Kidney renal clear cell carcinoma (KIRC) is one of the most hazardous tumors in the urinary system. The regulation of oxygen consumption in renal clear cell carcinoma is a consequence of adaptive reprogramming of oxidative metabolism in tumor cells. APPL1 is a signaling adaptor involved in cell survival, oxidative stress, inflammation, and energy metabolism. However, the correlation of APPL1 with regulatory T cell (Treg) infiltration and prognostic value in KIRC remain unclear. In this study, we comprehensively predicted the potential function and prognostic value of APPL1 in KIRC. For KIRC patients, relatively low expression of APPL1 was associated with high degree of metastasis, pathological stage, and shorter overall time or poor prognosis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses suggested that low expression of APPL1 may be adapted to the malignant progression of tumors via affecting oxygen-consuming metabolism. In addition, the expression level of APPL1 was negatively correlated with Treg cell infiltration and chemotherapy sensitivity, which indicated that APPL1 may regulate the tumor immune infiltration and chemotherapy resistance by decrease oxygen-consuming metabolic process in KIRC. Therefore, APPL1 may become one of the important prognostic factors, and it may serve as a candidate prognostic biomarker in KIRC.
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2
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Endosomal LC3C-pathway selectively targets plasma membrane cargo for autophagic degradation. Nat Commun 2022; 13:3812. [PMID: 35780247 PMCID: PMC9250516 DOI: 10.1038/s41467-022-31465-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 06/17/2022] [Indexed: 12/30/2022] Open
Abstract
Autophagy selectively targets cargo for degradation, yet mechanistic understanding remains incomplete. The ATG8-family plays key roles in autophagic cargo recruitment. Here by mapping the proximal interactome of ATG8-paralogs, LC3B and LC3C, we uncover a LC3C-Endocytic-Associated-Pathway (LEAP) that selectively recruits plasma-membrane (PM) cargo to autophagosomes. We show that LC3C localizes to peripheral endosomes and engages proteins that traffic between PM, endosomes and autophagosomes, including the SNARE-VAMP3 and ATG9, a transmembrane protein essential for autophagy. We establish that endocytic LC3C binds cargo internalized from the PM, including the Met receptor tyrosine kinase and transferrin receptor, and is necessary for their recruitment into ATG9 vesicles targeted to sites of autophagosome initiation. Structure-function analysis identified that LC3C-endocytic localization and engagement with PM-cargo requires the extended carboxy-tail unique to LC3C, the TBK1 kinase, and TBK1-phosphosites on LC3C. These findings identify LEAP as an unexpected LC3C-dependent pathway, providing new understanding of selective coupling of PM signalling with autophagic degradation.
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Jiang Z, Cheng X, Sun Z, Hu J, Xu X, Li M, Feng Z, Hu C. Grass carp PRMT6 negatively regulates innate immunity by inhibiting the TBK1/IRF3 binding and cutting down IRF3 phosphorylation level. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 129:104351. [PMID: 35033573 DOI: 10.1016/j.dci.2022.104351] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
Subcellular localization analysis implicated that CiPRMT6 was mainly located in the nucleus, with a small part of them located in the cytoplasm. PRMT6, namely protein arginine methyltransferase 6, was first identified and demonstrated to catalyze the methylation of arginine residue on the chromatin histones in mammals. Mammalian PRMT6 usually acts as an arginine methyltransferase in the nucleus, but induces antiviral innate immune response in the cytoplasm. Nowadays, there have been few reports about PRMT6 in teleost. In this study, we investigated the potential molecular mechanisms underlying the interaction of PRMT6 expression and IFN1 response in grass carp. We first cloned and identified a grass carp PRMT6 (named CiPRMT6, MN781672.1), which is 1068bp in length encoding a deduced polypeptide of 355 amino acids. In CIK cell, CiPRMT6 expression was up-regulated upon stimulation with poly (I:C); while overexpression of PRMT6 suppressed the promoter activity of grass carp IFN1 and reduced the phosphorylation of IRF3; however, the amount of PRMT6 mutant (lack of methyltransferase domain) was increased in the cytoplasm. Our results also showed that grass carp PRMT6 and IRF3 (but not TBK1) were co-located and bound to each other in the cytoplasm. The binding of CiPRMT6 to IRF3 impairs the interaction between TBK1 and IRF3, indicating that CiPRMT6 is a negative regulator for IFN1 expression through TBK1-IRF3 signaling pathway in grass carp. In conclusion, we identified that CiPRMT6 negatively regulated IFN1 expression by inhibiting the TBK1-IRF3 interaction as well as IRF3 phosphorylation.
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Affiliation(s)
- Zeyin Jiang
- School of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Xining Cheng
- School of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Zhichao Sun
- School of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Jihuan Hu
- School of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Xiaowen Xu
- School of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Meifeng Li
- School of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Zhiqing Feng
- School of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China
| | - Chengyu Hu
- School of Life Science, Key Lab of Aquatic Resources and Utilization of Jiangxi Province, Nanchang University, Nanchang, 330031, China.
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4
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The APPL1-Rab5 axis restricts NLRP3 inflammasome activation through early endosomal-dependent mitophagy in macrophages. Nat Commun 2021; 12:6637. [PMID: 34789781 PMCID: PMC8599493 DOI: 10.1038/s41467-021-26987-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/22/2021] [Indexed: 12/26/2022] Open
Abstract
Although mitophagy is known to restrict NLRP3 inflammasome activation, the underlying regulatory mechanism remains poorly characterized. Here we describe a type of early endosome-dependent mitophagy that limits NLRP3 inflammasome activation. Deletion of the endosomal adaptor protein APPL1 impairs mitophagy, leading to accumulation of damaged mitochondria producing reactive oxygen species (ROS) and oxidized cytosolic mitochondrial DNA, which in turn trigger NLRP3 inflammasome overactivation in macrophages. NLRP3 agonist causes APPL1 to translocate from early endosomes to mitochondria, where it interacts with Rab5 to facilitate endosomal-mediated mitophagy. Mice deficient for APPL1 specifically in hematopoietic cell are more sensitive to endotoxin-induced sepsis, obesity-induced inflammation and glucose dysregulation. These are associated with increased expression of systemic interleukin-1β, a major product of NLRP3 inflammasome activation. Our findings indicate that the early endosomal machinery is essential to repress NLRP3 inflammasome hyperactivation by promoting mitophagy in macrophages.
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5
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Qiu W, Wu H, Hu Z, Wu X, Tu M, Fang F, Zhu X, Liu Y, Lian J, Valverde P, Van Dyke T, Steffensen B, Dong LQ, Tu Q, Zhou X, Chen J. Identification and characterization of a novel adiponectin receptor agonist adipo anti-inflammation agonist and its anti-inflammatory effects in vitro and in vivo. Br J Pharmacol 2020; 178:280-297. [PMID: 32986862 DOI: 10.1111/bph.15277] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 08/11/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Adiponectin (APN) is an adipokine secreted from adipocytes that binds to APN receptors AdipoR1 and AdipoR2 and exerts an anti-inflammatory response through mechanisms not fully understood. There is a need to develop small molecules that activate AdipoR1 and AdipoR2 and to be used to inhibit the inflammatory response in lipopolysaccharide (LPS)-induced endotoxemia and other inflammatory disorders. EXPERIMENTAL APPROACH We designed 10 new structural analogues of an AdipoR agonist, AdipoRon (APR), and assessed their anti-inflammatory properties. Bone marrow-derived macrophages (BMMs) and peritoneal macrophages (PEMs) were isolated from mice. Levels of pro-inflammatory cytokines were measured by reverse transcription and real-time quantitative polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA) and microarray in LPS-induced endotoxemia mice and diet-induced obesity (DIO) mice in which systemic inflammation prevails. Western blotting, immunohistochemistry (IHC), siRNA interference and immunoprecipitation were used to detect signalling pathways. KEY RESULTS A novel APN receptor agonist named adipo anti-inflammation agonist (AdipoAI) strongly suppresses inflammation in DIO and endotoxemia mice, as well as in cultured macrophages. We also found that AdipoAI attenuated the association of AdipoR1 and APPL1 via myeloid differentiation marker 88 (MyD88) signalling, thus inhibiting activation of nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK) and c-Maf pathways and limiting the production of pro-inflammatory cytokines in LPS-induced macrophages. CONCLUSION AND IMPLICATIONS AdipoAI is a promising alternative therapeutic approach to APN and APR to suppress inflammation in LPS-induced endotoxemia and other inflammatory disorders via distinct signalling pathways.
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Affiliation(s)
- Wei Qiu
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA.,Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Hongle Wu
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA.,Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Zhekai Hu
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Xingwen Wu
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Maxwell Tu
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Fuchun Fang
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA.,Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xiaofang Zhu
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Yao Liu
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Junxiang Lian
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Paloma Valverde
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Thomas Van Dyke
- Clinical and Translational Research, Forsyth Institute, Cambridge, Massachusetts, USA.,Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Bjorn Steffensen
- Department of Periodontology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Lily Q Dong
- Department of Cell Systems and Anatomy, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Qisheng Tu
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA
| | - Xuedong Zhou
- State Key Laboratory of Oral Disease, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China.,Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jake Chen
- Division of Oral Biology, Tufts University School of Dental Medicine, Boston, Massachusetts, USA.,Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
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6
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Sin WX, Yeong JPS, Lim TJF, Su IH, Connolly JE, Chin KC. IRF-7 Mediates Type I IFN Responses in Endotoxin-Challenged Mice. Front Immunol 2020; 11:640. [PMID: 32373120 PMCID: PMC7176903 DOI: 10.3389/fimmu.2020.00640] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 03/20/2020] [Indexed: 01/23/2023] Open
Abstract
IRF-7 mediates robust production of type I IFN via MyD88 of the TLR9 pathway in plasmacytoid dendritic cells (pDCs). Previous in vitro studies using bone marrow-derived dendritic cells lacking either Irf7 or Irf3 have demonstrated that only IRF-3 is required for IFN-β production in the TLR4 pathway. Here, we show that IRF-7 is essential for both type I IFN induction and IL-1β responses via TLR4 in mice. Mice lacking Irf7 were defective in production of both IFN-β and IL-1β, an IFN-β-induced pro-inflammatory cytokine, after LPS challenge. IFN-β production in response to LPS was impaired in IRF-7-deficient macrophages, but not dendritic cells. Unlike pDCs, IRF-7 is activated by the TRIF-, but not MyD88-, dependent pathway via TBK-1 in macrophages after LPS stimulation. Like pDCs, resting macrophages constitutively expressed IRF-7 protein. This basal IRF-7 protein was completely abolished in either Ifnar1 -/- or Stat1 -/- macrophages, which corresponded with the loss of LPS-stimulated IFN-β induction in these macrophages. These findings demonstrate that macrophage IRF-7 is critical for LPS-induced type I IFN responses, which in turn facilitate IL-1β production in mice.
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Affiliation(s)
- Wei-Xiang Sin
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore
| | - Joe Poh-Sheng Yeong
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore.,Division of Pathology, Singapore General Hospital, Singapore, Singapore
| | - Thomas Jun Feng Lim
- School of Biological Sciences, College of Science, Nanyang Technological University, Singapore, Singapore
| | - I-Hsin Su
- School of Biological Sciences, College of Science, Nanyang Technological University, Singapore, Singapore
| | - John E Connolly
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore.,Institute of Biomedical Studies, Baylor University, Waco, TX, United States
| | - Keh-Chuang Chin
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Singapore.,Department of Physiology, NUS Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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7
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Luo L, Lucas RM, Liu L, Stow JL. Signalling, sorting and scaffolding adaptors for Toll-like receptors. J Cell Sci 2019; 133:133/5/jcs239194. [PMID: 31889021 DOI: 10.1242/jcs.239194] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Toll-like receptors (TLRs) are danger-sensing receptors that typically propagate self-limiting inflammatory responses, but can unleash uncontrolled inflammation in non-homeostatic or disease settings. Activation of TLRs by pathogen- and/or host-derived stimuli triggers a range of signalling and transcriptional pathways to programme inflammatory and anti-microbial responses, including the production of a suite of inflammatory cytokines and other mediators. Multiple sorting and signalling adaptors are recruited to receptor complexes on the plasma membrane or endosomes where they act as scaffolds for downstream signalling kinases and effectors at these sites. So far, seven proximal TLR adaptors have been identified: MyD88, MAL, TRIF (also known as TICAM1), TRAM (TICAM2), SARM (SARM1), BCAP (PIK3AP1) and SCIMP. Most adaptors tether directly to TLRs through homotypic Toll/interleukin-1 receptor domain (TIR)-TIR interactions, whereas SCIMP binds to TLRs through an atypical TIR-non-TIR interaction. In this Review, we highlight the key roles for these adaptors in TLR signalling, scaffolding and receptor sorting and discuss how the adaptors thereby direct the differential outcomes of TLR-mediated responses. We further summarise TLR adaptor regulation and function, and make note of human diseases that might be associated with mutations in these adaptors.
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Affiliation(s)
- Lin Luo
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Richard M Lucas
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Liping Liu
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, QLD 4072, Australia
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8
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Zhang Y, Huang Z, Li H. Insights into innate immune signalling in controlling cardiac remodelling. Cardiovasc Res 2017; 113:1538-1550. [DOI: 10.1093/cvr/cvx130] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 06/29/2017] [Indexed: 01/22/2023] Open
Affiliation(s)
- Yaxing Zhang
- Department of Cardiology, Renmin Hospital of Wuhan University, Jiefang Road 238, Wuchang District, Wuhan 430060, People’s Republic of China
- Institute of Model Animal of Wuhan University, Donghu Road 115, Wuchang District, Wuhan 430071, People’s Republic of China
- Medical Research Institute, School of Medicine, Wuhan University, Donghu Road 115, Wuchang District, Wuhan 430071, People’s Republic of China
| | - Zan Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Jiefang Road 238, Wuchang District, Wuhan 430060, People’s Republic of China
- Institute of Model Animal of Wuhan University, Donghu Road 115, Wuchang District, Wuhan 430071, People’s Republic of China
- Medical Research Institute, School of Medicine, Wuhan University, Donghu Road 115, Wuchang District, Wuhan 430071, People’s Republic of China
- College of Life Sciences, Wuhan University, Wuhan 430072, People’s Republic of China
| | - Hongliang Li
- Department of Cardiology, Renmin Hospital of Wuhan University, Jiefang Road 238, Wuchang District, Wuhan 430060, People’s Republic of China
- Institute of Model Animal of Wuhan University, Donghu Road 115, Wuchang District, Wuhan 430071, People’s Republic of China
- Medical Research Institute, School of Medicine, Wuhan University, Donghu Road 115, Wuchang District, Wuhan 430071, People’s Republic of China
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9
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Jiang X, Zhou Y, Wu KKL, Chen Z, Xu A, Cheng KKY. APPL1 prevents pancreatic beta cell death and inflammation by dampening NFκB activation in a mouse model of type 1 diabetes. Diabetologia 2017; 60:464-474. [PMID: 28011992 DOI: 10.1007/s00125-016-4185-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 11/17/2016] [Indexed: 11/28/2022]
Abstract
AIMS/HYPOTHESIS Beta cell inflammation and demise is a feature of type 1 diabetes. The insulin-sensitising molecule 'adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1' (APPL1), which contains an NH2-terminal Bin/Amphiphysin/Rvs domain, a central pleckstrin homology domain and a COOH-terminal phosphotyrosine-binding domain, has been shown to modulate inflammatory response in various cell types but its role in regulating beta cell mass and inflammation in type 1 diabetes remains unknown. Thus, we investigated whether APPL1 prevents beta cell apoptosis and inflammation in diabetes. METHODS Appl1-knockout mice and their wild-type littermates, as well as C57BL/6N mice injected with adeno-associated virus encoding APPL1 or green fluorescent protein, were treated with multiple-low-dose streptozotocin (MLDS) to induce experimental type 1 diabetes. Their glucose metabolism and beta cell function were assessed. The effect of APPL1 deficiency on beta cell function upon exposure to a diabetogenic cytokine cocktail (CKS; consisting of TNF-α, IL-1β and IFN-γ) was assessed ex vivo. RESULTS Expression of APPL1 was significantly reduced in pancreatic islets from mouse models of type 1 diabetes or islets treated with CKS. Hyperglycaemia, beta cell loss and insulitis induced by MLDS were exacerbated by genetic deletion of Appl1 but were alleviated by beta cell-specific overexpression of APPL1. APPL1 preserved beta cell mass by reducing beta cell apoptosis upon treatment with MLDS. Mechanistically, APPL1 deficiency potentiate CKS-induced phosphorylation of NFκB inhibitor, α (IκBα) and subsequent phosphorylation and transcriptional activation of p65, leading to a dramatic induction of NFκB-regulated apoptotic and proinflammatory programs in beta cells. Pharmacological inhibition of NFκB or inducible NO synthase (iNOS) largely abrogate the detrimental effects of APPL1 deficiency on beta cell functions. CONCLUSIONS/INTERPRETATION APPL1 negatively regulates inflammation and apoptosis in pancreatic beta cells by dampening the NFκB-iNOS-NO axis, representing a promising target for treating type 1 diabetes.
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Affiliation(s)
- Xue Jiang
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, L8, 21 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China
- Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China
| | - Yawen Zhou
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, L8, 21 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China
- Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China
| | - Kelvin K L Wu
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, L8, 21 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China
- Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China
| | - Zhanrui Chen
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, L8, 21 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China
- Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China
| | - Aimin Xu
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, L8, 21 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China.
- Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China.
- Department of Pharmacology & Pharmacy, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China.
| | - Kenneth K Y Cheng
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, L8, 21 Sassoon Road, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China.
- Department of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, People's Republic of China.
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10
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Liu Z, Xiao T, Peng X, Li G, Hu F. APPLs: More than just adiponectin receptor binding proteins. Cell Signal 2017; 32:76-84. [PMID: 28108259 DOI: 10.1016/j.cellsig.2017.01.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/13/2017] [Accepted: 01/13/2017] [Indexed: 12/31/2022]
Abstract
APPLs (adaptor proteins containing the pleckstrin homology domain, phosphotyrosine binding domain and leucine zipper motif) are multifunctional adaptor proteins that bind to various membrane receptors, nuclear factors and signaling proteins to regulate many biological activities and processes, such as cell proliferation, chromatin remodeling, endosomal trafficking, cell survival, cell metabolism and apoptosis. APPL1, one of the APPL isoforms, was the first identified protein and interacts directly with adiponectin receptors to mediate adiponectin signaling to enhance lipid oxidation and glucose uptake. APPLs also act on insulin signaling pathways and are important mediators of insulin sensitization. Based on recent findings, this review highlights the critical roles of APPLs, particularly APPL1 and its isoform partner APPL2, in mediating adiponectin, insulin, endosomal trafficking and other signaling pathways. A deep understanding of APPLs and their related signaling pathways may potentially lead to therapeutic and interventional treatments for obesity, diabetes, cancer and neurodegenerative diseases.
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Affiliation(s)
- Zhuoying Liu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Ting Xiao
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Xiaoyu Peng
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Guangdi Li
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China
| | - Fang Hu
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center of Central South University, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China.
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11
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Wang LC, Kennedy TE, Almazan G. A novel function of TBK1 as a target of Cdon in oligodendrocyte differentiation and myelination. J Neurochem 2016; 140:451-462. [PMID: 27797401 DOI: 10.1111/jnc.13882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 09/21/2016] [Accepted: 10/25/2016] [Indexed: 11/28/2022]
Abstract
During central nervous system development, oligodendrocyte progenitors elaborate multiple branched processes to contact axons and initiate myelination. Using cultured primary rat oligodendrocytes (OLGs), we have recently demonstrated that a cell surface protein belonging to the immunoglobulin superfamily, cell adhesion molecule-related, down-regulated by oncogenes (Cdon), is important in initiating OLG differentiation and axon myelination by promoting the formation of branched cellular processes; however, the molecular mechanism by which Cdon regulates OLG differentiation is not known. Here, using Cdon immunoprecipitation (IP) and liquid chromatography-tandem mass spectrometry analysis, we identified serine/threonine kinase TANK-binding kinase 1 (TBK1) as a candidate novel target of Cdon. We confirmed this interaction using co-IP and immunofluorescence with TBK1 antibodies, showing that TBK1 partly co-localizes with Cdon along cellular processes in puncta-like structures. We show that TBK1 is expressed throughout OLG differentiation, and surprisingly, that levels of phosphorylated TBK1 (ser172) increase during OLG maturation, while total levels of TBK1 protein decrease. To investigate function, TBK1 expression was knocked down using siRNA in OLG primary cultures, reducing protein levels by 69%. Two myelin-specific proteins, myelin basic protein and myelin-associated glycoprotein, were similarly reduced when examined at day 2 and day 4 of OLG differentiation. Reduced Cdon or TBK1 expression also decreased Akt phosphorylation at Threonine 308 in OLG. Our findings provide evidence that a Cdon-TBK1 complex is associated with Akt phosphorylation and early OLG differentiation.
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Affiliation(s)
- Li-Chun Wang
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | - Timothy E Kennedy
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Guillermina Almazan
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
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Yeo JC, Wall AA, Luo L, Condon ND, Stow JL. Distinct Roles for APPL1 and APPL2 in Regulating Toll-like Receptor 4 Signaling in Macrophages. Traffic 2016; 17:1014-26. [PMID: 27219021 DOI: 10.1111/tra.12415] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 05/09/2016] [Accepted: 05/09/2016] [Indexed: 12/17/2022]
Abstract
Macrophages are activated by contact with pathogens to mount innate immune defenses against infection. Toll-like receptor 4 (TLR4) at the macrophage surface recognizes and binds bacterial lipopolysaccharide (LPS), setting off signaling and transcriptional events that lead to the secretion of pro- and anti-inflammatory cytokines; these in turn control inflammatory and antimicrobial responses. Although the complex regulatory pathways downstream of TLR4 have been extensively studied, further molecules critical for modulating the resulting cytokine outputs remain to be characterized. Here we establish potential roles for APPL1 and 2 signaling adaptors as regulators of LPS/TLR4-induced signaling, transcription, and cytokine secretion. APPL1 and 2 are differentially localized to distinct signaling-competent membrane domains on the surface and in endocytic compartments of LPS-activated macrophages. By depleting cells of each adaptor respectively we show separate and opposing functions for APPL1 and 2 in Akt and MAPK signaling. Specifically, APPL2 has a dominant role in nuclear translocation of NF-KB p65 and it serves to constrain the secretion of pro- and anti-inflammatory cytokines. The APPLs, and in particular APPL2, are thus revealed as adaptors with important capacity to modulate inflammatory responses mounted by LPS/TLR4 during infection.
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Affiliation(s)
- Jeremy C Yeo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Adam A Wall
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Lin Luo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Nicholas D Condon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Jennifer L Stow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
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Wei D, Li NL, Zeng Y, Liu B, Kumthip K, Wang TT, Huo D, Ingels JF, Lu L, Shang J, Li K. The Molecular Chaperone GRP78 Contributes to Toll-like Receptor 3-mediated Innate Immune Response to Hepatitis C Virus in Hepatocytes. J Biol Chem 2016; 291:12294-309. [PMID: 27129228 DOI: 10.1074/jbc.m115.711598] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Indexed: 01/26/2023] Open
Abstract
Toll-like receptor-3 (TLR3) senses double-stranded RNA intermediates produced during hepatitis C virus (HCV) replication, leading to activation of interferon regulatory factor-3 (IRF3) and NF-κB and subsequent antiviral and proinflammatory responses. Yet, how this TLR3-dependent pathway operates in hepatocytes is unclear. Upon fractionating cultured hepatocytes into various cellular organelles, we observed that TLR3 predominantly resides in endolysosomes of hepatocytes. To determine the critical regulators of TLR3 signaling in response to HCV infection in human hepatocytes, we isolated endolysosome fractions from mock-infected and HCV-infected hepatoma Huh7.5 cells that had been reconstituted for TLR3 expression, separated these fractions on two-dimensional gels, and identified up-regulated/down-regulated proteins by mass spectrometry. Approximately a dozen of cellular proteins were found to be differentially expressed in endolysosome fractions following HCV infection. Of these, expression of several molecular chaperone proteins was elevated. Knockdown of one of these chaperones, glucose-regulated protein 78 kDa (GRP78), compromised TLR3-dependent induction of interferon-stimulated genes and chemokines following HCV infection or poly(I:C) stimulation in cultured hepatocytes. Consistent with this finding, GRP78 depletion impaired TLR3-mediated establishment of an antiviral state. Mechanistically, although TLR3 trafficking to endolysosomes was not affected, phosphorylated IRF3 diminished faster following GRP78 knockdown. Remarkably, GRP78 transcript was significantly up-regulated in liver biopsies of chronic hepatitis C patients as compared with normal liver tissues. Moreover, the GRP78 expression level correlated with that of RANTES (regulated upon activation, normal T-cell expressed and secreted) and CXCL10, two inflammatory chemokines most frequently elevated in HCV-infected liver. Altogether, our data suggest that GRP78 contributes to TLR3-mediated, IRF3-dependent innate immune response to HCV in hepatocytes.
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Affiliation(s)
- Dahai Wei
- From the Departments of Microbiology, Immunology and Biochemistry and
| | - Nan L Li
- From the Departments of Microbiology, Immunology and Biochemistry and
| | - Yanli Zeng
- the Department of Infectious Diseases, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
| | - Baoming Liu
- From the Departments of Microbiology, Immunology and Biochemistry and
| | | | - Tony T Wang
- the SRI International, Harrisonburg, Virginia 22802, and
| | - Dezheng Huo
- the Department of Public Health Sciences, University of Chicago, Chicago, Illinois 60637
| | - Jesse F Ingels
- Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Lu Lu
- Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Jia Shang
- the Department of Infectious Diseases, Henan Provincial People's Hospital, Zhengzhou, Henan 450003, China
| | - Kui Li
- From the Departments of Microbiology, Immunology and Biochemistry and
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Li J, Zhou M, Peng L, Sun W, Yang P, Yan J, Feng H. Identification and characterization of IKKε gene from grass carp Ctenopharyngodon idella. FISH & SHELLFISH IMMUNOLOGY 2015; 47:255-263. [PMID: 26370541 DOI: 10.1016/j.fsi.2015.09.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/01/2015] [Accepted: 09/07/2015] [Indexed: 06/05/2023]
Abstract
IKKε is an IKK-related kinase implicated in antiviral immune response in higher vertebrates. To elucidate the function of IKKε in teleost fish, grass carp IKKε (gcIKKε) has been cloned and characterized in this paper. The full-length cDNA of gcIKKε is composed of 2529 nucleotides and encodes a polypeptide of 723 amino acids. The mRNA transcription of gcIKKε was constitutively detected in all the selected tissues and the gcIKKε mRNA level increased at 36 h after GCRV infection. Western blot data of both HEK293T cells and EPC cells demonstrated that gcIKKε was around 80 KDa; and immunofluorescence staining data of both NIH3T3 cells and EPC cells determined gcIKKε was a cytosolic protein. The mRNA level of gcIKKε in CIK cells was increased more than 150 times right after poly(I:C) treatment and PMA treatment triggered gcIKKε mRNA transcription in CIK cells more than 100 times. Over-expression of gcIKKε in EPC cells activated the promoter activity of both zebrafish IFN and fathead minnow IFN. gcIKKε mRNA transcription level in CIK cells was increased from 48 h post GCRV infection with different MOIs. All the data support the idea that gcIKKε is a novel teleost IκB kinase recruited in the IFN-mediated antiviral immunity of grass carp.
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Affiliation(s)
- Jun Li
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education of China, College of Life Science, Hunan Normal University, Changsha 410081, China
| | - Man Zhou
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education of China, College of Life Science, Hunan Normal University, Changsha 410081, China
| | - Lingzhi Peng
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education of China, College of Life Science, Hunan Normal University, Changsha 410081, China
| | - Wenzheng Sun
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education of China, College of Life Science, Hunan Normal University, Changsha 410081, China
| | - Peilin Yang
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education of China, College of Life Science, Hunan Normal University, Changsha 410081, China
| | - Jun Yan
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education of China, College of Life Science, Hunan Normal University, Changsha 410081, China
| | - Hao Feng
- Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education of China, College of Life Science, Hunan Normal University, Changsha 410081, China.
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