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Chen J, Zhao H, Liu M, Chen L. A new perspective on the autophagic and non-autophagic functions of the GABARAP protein family: a potential therapeutic target for human diseases. Mol Cell Biochem 2023:10.1007/s11010-023-04800-5. [PMID: 37440122 DOI: 10.1007/s11010-023-04800-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 06/24/2023] [Indexed: 07/14/2023]
Abstract
Mammalian autophagy-related protein Atg8, including the LC3 subfamily and GABARAP subfamily. Atg8 proteins play a vital role in autophagy initiation, autophagosome formation and transport, and autophagy-lysosome fusion. GABARAP subfamily proteins (GABARAPs) share a high degree of homology with LC3 family proteins, and their unique roles are often overlooked. GABARAPs are as indispensable as LC3 in autophagy. Deletion of GABARAPs fails autophagy flux induction and autophagy lysosomal fusion, which leads to the failure of autophagy. GABARAPs are also involved in the transport of selective autophagy receptors. They are engaged in various particular autophagy processes, including mitochondrial autophagy, endoplasmic reticulum autophagy, Golgi autophagy, centrosome autophagy, and dorphagy. Furthermore, GABARAPs are closely related to the transport and delivery of the inhibitory neurotransmitter γ-GABAA and the angiotensin II AT1 receptor (AT1R), tumor growth, metastasis, and prognosis. GABARAPs also have been confirmed to be involved in various diseases, such as cancer, cardiovascular disease, and neurodegenerative diseases. In order to better understand the role and therapeutic potential of GABARAPs, this article comprehensively reviews the autophagic and non-autophagic functions of GABARAPs, as well as the research progress of the role and mechanism of GABARAPs in cancer, cardiovascular diseases and neurodegenerative diseases. It emphasizes the significance of GABARAPs in the clinical prevention and treatment of diseases, and may provide new therapeutic ideas and targets for human diseases. GABARAP and GABARAPL1 in the serum of cancer patients are positively correlated with the prognosis of patients, which can be used as a clinical biomarker, predictor and potential therapeutic target. GABARAP family proteins: autophagy and non-autophagy related functions in diseases. By Figdraw ( https://www.figdraw.com ).
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Affiliation(s)
- Jiawei Chen
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Hong Zhao
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
- School of Nursing, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China
| | - Meiqing Liu
- Central Laboratory of Yan'nan Hospital Affiliated to Kunming, Medical University, Key Laboratory of Cardiovascular Diseases of Yunnan Province, Key Laboratory of Tumor Immunological Prevention and Treatment of Yunnan Province, No. 245, Renmin East Road, Kunming, 650000, Yunnan, China.
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, 421001, Hunan, China.
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Yu YL, Zhang MT, Huo Y, Tang JL, Liu Q, Chen XY, Fang RX, Zhang LL. Laodelphax striatellus Atg8 facilitates Rice stripe virus infection in an autophagy-independent manner. INSECT SCIENCE 2021; 28:315-329. [PMID: 32108430 DOI: 10.1111/1744-7917.12771] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/21/2020] [Accepted: 02/22/2020] [Indexed: 06/10/2023]
Abstract
Rice stripe virus (RSV) is the causative agent of rice stripe disease and is completely dependent on insect vectors for its plant-to-plant transmission. Laodelphax striatellus is the major insect vector for RSV. In this study, we explored the interactions between RSV infection and L. striatellus autophagy, a potential intrinsic antiviral mechanism in insects. We found that L. striatellus autophagic activity did not affect RSV infection; however, the autophagy-related-8 (Atg8) gene significantly enhanced virus infection. During RSV initial infection within the L. striatellus midgut, silencing of Atg8 expression significantly decreased the phosphorylation of c-Jun N-terminal kinase (p-JNK); however, when RSV infection is absent, silencing of Atg8 did not alter p-JNK levels. These results indicated that Atg8 might activate the JNK machinery by allowing more virus infection into cells. We further revealed that Atg8-deficiency significantly decreased RSV accumulation on the surface of the insect midgut epithelial cells, suggesting a receptor trafficking function of the γ-aminobutyric acid receptor-associated protein family. Using the RSV ovary entry as a model, in which vitellogenin receptor (VgR) mediates RSV cell entry, we clarified that Atg8-deficiency decreased the abundance of VgR localizing on the cytomembrane and disturbed the attachment of RSV in the germarium zones. Collectively, these results revealed an autophagy-independent function of L. striatellus Atg8 that enhances RSV initial infection by increasing virus attachment on the infection sites.
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Affiliation(s)
- Yuan-Ling Yu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Science, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing, China
| | - Meng-Ting Zhang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Science, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing, China
| | - Yan Huo
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Science, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing, China
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, China
| | - Qing Liu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Science, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing, China
| | - Xiao-Ying Chen
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Science, Beijing, China
| | - Rong-Xiang Fang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Science, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing, China
- National Plant Gene Research Center, Beijing, China
| | - Li-Li Zhang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Science, Beijing, China
- CAS Center for Excellence in Biotic Interactions, University of the Chinese Academy of Sciences, Beijing, China
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Jacquet M, Guittaut M, Fraichard A, Despouy G. The functions of Atg8-family proteins in autophagy and cancer: linked or unrelated? Autophagy 2021; 17:599-611. [PMID: 32255730 PMCID: PMC8032235 DOI: 10.1080/15548627.2020.1749367] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 03/09/2020] [Accepted: 03/26/2020] [Indexed: 01/04/2023] Open
Abstract
The Atg8-family proteins are subdivided into two subfamilies: the GABARAP and LC3 subfamilies. These proteins, which are major players of the autophagy pathway, present a conserved glycine in their C-terminus necessary for their association to the autophagosome membrane. This family of proteins present multiple roles from autophagy induction to autophagosome-lysosome fusion and have been described to play a role during cancer progression. Indeed, GABARAPs are described to be downregulated in cancers, and high expression has been linked to a good prognosis. Regarding LC3 s, their expression does not correlate to a particular tumor type or stage. The involvement of Atg8-family proteins during cancer, therefore, remains unclear, and it appears that their anti-tumor role may be associated with their implication in selective protein degradation by autophagy but might also be independent, in some cases, of their conjugation to autophagosomes. In this review, we will then focus on the involvement of GABARAP and LC3 subfamilies during autophagy and cancer and highlight the similarities but also the differences of action of each subfamily member.Abbreviations: AIM: Atg8-interacting motif; AMPK: adenosine monophosphate-associated protein kinase; ATG: autophagy-related; BECN1: beclin 1; BIRC6/BRUCE: baculoviral IAP repeat containing 6; BNIP3L/NIX: BCL2 interacting protein 3 like; GABARAP: GABA type A receptor-associated protein; GABARAPL1/2: GABA type A receptor associated protein like 1/2; GABRA/GABAA: gamma-aminobutyric acid type A receptor subunit; LAP: LC3-associated phagocytosis; LMNB1: lamin B1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; PI4K2A/PI4KIIα: phosphatidylinositol 4-kinase type 2 alpha; PLEKHM1: plecktrin homology and RUN domain containing M1; PtdIns3K-C1: class III phosphatidylinositol 3-kinase complex 1; SQSTM1: sequestosome 1; ULK1: unc51-like autophagy activating kinase 1.
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Affiliation(s)
- Marine Jacquet
- Univ. Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, Besançon, France
| | - Michaël Guittaut
- Univ. Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, Besançon, France
- DImaCell Platform, Univ. Bourgogne Franche-Comté, Besançon, France
| | - Annick Fraichard
- Univ. Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, Besançon, France
| | - Gilles Despouy
- Univ. Bourgogne Franche-Comté, INSERM, EFS BFC, UMR1098, Interactions Hôte-Greffon-Tumeur/Ingénierie Cellulaire et Génique, Besançon, France
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Zhang M, Wu G. Mechanisms of the anterograde trafficking of GPCRs: Regulation of AT1R transport by interacting proteins and motifs. Traffic 2018; 20:110-120. [PMID: 30426616 DOI: 10.1111/tra.12624] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/29/2018] [Accepted: 11/08/2018] [Indexed: 12/11/2022]
Abstract
Anterograde cell surface transport of nascent G protein-coupled receptors (GPCRs) en route from the endoplasmic reticulum (ER) through the Golgi apparatus represents a crucial checkpoint to control the amount of the receptors at the functional destination and the strength of receptor activation-elicited cellular responses. However, as compared with extensively studied internalization and recycling processes, the molecular mechanisms of cell surface trafficking of GPCRs are relatively less defined. Here, we will review the current advances in understanding the ER-Golgi-cell surface transport of GPCRs and use angiotensin II type 1 receptor as a representative GPCR to discuss emerging roles of receptor-interacting proteins and specific motifs embedded within the receptors in controlling the forward traffic of GPCRs along the biosynthetic pathway.
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Affiliation(s)
- Maoxiang Zhang
- Guangzhou University of Chinese Medicine, Guangzhou, China.,Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia
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Chen Y, Sun HQ, Eichorst JP, Albanesi JP, Yin H, Mueller JD. Comobility of GABARAP and Phosphatidylinositol 4-Kinase 2A on Cytoplasmic Vesicles. Biochemistry 2018; 57:3556-3559. [PMID: 29792687 DOI: 10.1021/acs.biochem.8b00224] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We previously reported that recruitment of the type IIA phosphatidylinositol 4-kinase (PI4K2A) to autophagosomes by GABARAP, a member of the Atg8 family of autophagy-related proteins, is important for autophagosome-lysosome fusion. Because both PI4K2A and GABARAP have also been implicated in the intracellular trafficking of plasma membrane receptors in the secretory/endocytic pathway, we characterized their interaction in cells under nonautophagic conditions. Fluorescence fluctuation spectroscopy measurements revealed that GABARAP exists predominantly as a cytosolic monomer in live cells, but is recruited to small cytoplasmic vesicles upon overexpression of PI4K2A. C-Terminal lipidation of GABARAP, which is essential for its autophagic activities, is not necessary for its recruitment to these PI4K2A-containing transport vesicles. However, a GABARAP truncation mutant lacking C-terminal residues 103-117 fails to bind to PI4K2A, is not recruited to cytoplasmic vesicles, and does not codistribute with PI4K2A on subcellular organelles. These observations suggest that the PI4K2A-GABARAP interaction plays a role in membrane trafficking both under autophagic and nonautophagic conditions.
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Affiliation(s)
- Yan Chen
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | | | - John P Eichorst
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | | | | | - Joachim D Mueller
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 , United States
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Direct binding to GABARAP family members is essential for HIV-1 Nef plasma membrane localization. Sci Rep 2017; 7:5979. [PMID: 28729737 PMCID: PMC5519724 DOI: 10.1038/s41598-017-06319-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/12/2017] [Indexed: 12/29/2022] Open
Abstract
HIV-1 Nef is an important pathogenic factor for HIV/AIDS pathogenesis. Studies have shown that the association of Nef with the inner leaflet of the plasma membrane and with endocytic and perinuclear vesicles is essential for most activities of Nef. Using purified recombinant proteins in pull-down assays and by co-immunoprecipitation assays we demonstrate that Nef binds directly and specifically to all GABARAP family members, but not to LC3 family members. Based on nuclear magnetic resonance (NMR) experiments we showed that Nef binds to GABARAP via two surface exposed hydrophobic pockets. S53 and F62 of GABARAP were identified as key residues for the interaction with Nef. During live-cell fluorescence microscopy an accumulation of Nef and all GABARAP family members in vesicular structures throughout the cytoplasm and at the plasma membrane was observed. This plasma membrane accumulation was significantly reduced after knocking down GABARAP, GABARAPL1 and GABARAPL2 with respective siRNAs. We identified GABARAPs as the first known direct interaction partners of Nef that are essential for its plasma membrane localization.
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Keulers TG, Schaaf MBE, Rouschop KMA. Autophagy-Dependent Secretion: Contribution to Tumor Progression. Front Oncol 2016; 6:251. [PMID: 27933272 PMCID: PMC5122571 DOI: 10.3389/fonc.2016.00251] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 11/10/2016] [Indexed: 12/14/2022] Open
Abstract
Autophagy is best known as a lysosomal degradation and recycling pathway to maintain cellular homeostasis. During autophagy, cytoplasmic content is recognized and packed in autophagic vacuoles, or autophagosomes, and targeted for degradation. However, during the last years, it has become evident that the role of autophagy is not restricted to degradation alone but also mediates unconventional forms of secretion. Furthermore, cells with defects in autophagy apparently are able to reroute their cargo, like mitochondria, to the extracellular environment; effects that contribute to an array of pathologies. In this review, we discuss the current knowledge of the physiological roles of autophagy-dependent secretion, i.e., the effect on inflammation and insulin/hormone secretion. Finally, we focus on the effects of autophagy-dependent secretion on the tumor microenvironment (TME) and tumor progression. The autophagy-mediated secreted factors may stimulate cellular proliferation via auto- and paracrine signaling. The autophagy-mediated release of immune modulating proteins changes the immunosuppresive TME and may promote an invasive phenotype. These effects may be either direct or indirect through facilitating formation of the mobilized vesicle, aid in anterograde trafficking, or alterations in homeostasis and/or autonomous cell signaling.
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Affiliation(s)
- Tom G Keulers
- Maastricht Radiation Oncology (MaastRO) Lab, GROW - School for Oncology and Developmental Biology, Maastricht University Medical Center , Maastricht , Netherlands
| | - Marco B E Schaaf
- Cell Death Research and Therapy (CDRT) Laboratory, Department Cellular and Molecular Medicine, KU Leuven, University of Leuven , Leuven , Belgium
| | - Kasper M A Rouschop
- Maastricht Radiation Oncology (MaastRO) Lab, GROW - School for Oncology and Developmental Biology, Maastricht University Medical Center , Maastricht , Netherlands
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Schaaf MBE, Keulers TG, Vooijs MA, Rouschop KMA. LC3/GABARAP family proteins: autophagy-(un)related functions. FASEB J 2016; 30:3961-3978. [PMID: 27601442 DOI: 10.1096/fj.201600698r] [Citation(s) in RCA: 399] [Impact Index Per Article: 49.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/22/2016] [Indexed: 01/01/2023]
Abstract
From yeast to mammals, autophagy is an important mechanism for sustaining cellular homeostasis through facilitating the degradation and recycling of aged and cytotoxic components. During autophagy, cargo is captured in double-membraned vesicles, the autophagosomes, and degraded through lysosomal fusion. In yeast, autophagy initiation, cargo recognition, cargo engulfment, and vesicle closure is Atg8 dependent. In higher eukaryotes, Atg8 has evolved into the LC3/GABARAP protein family, consisting of 7 family proteins [LC3A (2 splice variants), LC3B, LC3C, GABARAP, GABARAPL1, and GABARAPL2]. LC3B, the most studied family protein, is associated with autophagosome development and maturation and is used to monitor autophagic activity. Given the high homology, the other LC3/GABARAP family proteins are often presumed to fulfill similar functions. Nevertheless, substantial evidence shows that the LC3/GABARAP family proteins are unique in function and important in autophagy-independent mechanisms. In this review, we discuss the current knowledge and functions of the LC3/GABARAP family proteins. We focus on processing of the individual family proteins and their role in autophagy initiation, cargo recognition, vesicle closure, and trafficking, a complex and tightly regulated process that requires selective presentation and recruitment of these family proteins. In addition, functions unrelated to autophagy of the LC3/GABARAP protein family members are discussed.-Schaaf, M. B. E., Keulers, T. G, Vooijs, M. A., Rouschop, K. M. A. LC3/GABARAP family proteins: autophagy-(un)related functions.
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Affiliation(s)
- Marco B E Schaaf
- Department of Radiation Oncology (Maastro Lab), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Tom G Keulers
- Department of Radiation Oncology (Maastro Lab), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Marc A Vooijs
- Department of Radiation Oncology (Maastro Lab), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Kasper M A Rouschop
- Department of Radiation Oncology (Maastro Lab), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
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Keulers TG, Schaaf MB, Peeters HJ, Savelkouls KG, Vooijs MA, Bussink J, Jutten B, Rouschop KM. GABARAPL1 is required for increased EGFR membrane expression during hypoxia. Radiother Oncol 2015; 116:417-22. [DOI: 10.1016/j.radonc.2015.06.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/16/2015] [Accepted: 06/17/2015] [Indexed: 10/23/2022]
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Re RN. Thirty years of intracrinology. Ochsner J 2014; 14:673-680. [PMID: 25598734 PMCID: PMC4295746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
BACKGROUND Intracrinology is the study of the intracellular actions, regulation, trafficking, and interactions of extracellular signaling peptides/proteins. METHODS We describe the development of intracrine biology since the term was defined in 1984. RESULTS Intracrine biology plays a role in many normal and pathological processes and represents a fertile field for the development of novel therapeutics. CONCLUSION Although 30 years old, the field of intracrinology is only now becoming widely accepted. Intracrine principles can be applied to the investigation of physiological processes and to the development of new therapies.
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Affiliation(s)
- Richard N Re
- Research Division, Ochsner Health System, New Orleans, LA
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Zhao ZG, Niu CY, Qiu JF, Chen XD, Li JC. Effect of mesenteric lymph duct ligation on gene expression profiles of renal tissue in hemorrhagic shock rats with fluid resuscitation. Ren Fail 2013; 36:271-7. [DOI: 10.3109/0886022x.2013.844623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Rho SB, Byun HJ, Kim BR, Kim IS, Lee JH, Yoo R, Park ST, Park SH. GABAA receptor-binding protein promotes sensitivity to apoptosis induced by chemotherapeutic agents. Int J Oncol 2013; 42:1807-14. [PMID: 23545901 DOI: 10.3892/ijo.2013.1866] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/08/2013] [Indexed: 11/06/2022] Open
Abstract
In the present study, the expression of human γ-aminobutyrate type A (GABAA) receptor-binding protein (GABARBP) is downregulated in ovarian cancer cell lines and tissues. We also found that the specific function of GABAPBP was that of a novel pro-apoptotic protein. Both GABARBP and cisplatin suppressed cancer cell proliferation in a concentration-dependent manner. The combined treatment of GABARBP and cisplatin was more effective in inhibiting cell growth, as well as cell migration, than with either drug treatment alone. At the same time, the treatment combination is correlated with the downregulation of cyclin D1 and CDK4, arrested cell cycle progression in the G₀-G₁ phase and enhancing p53 expression, while also reducing Bcl-2 and Bcl-xL expression. The p53 and p21 promoter luciferase activities were induced by GABARBP, whereas there was no effect on the p53-/- and p21-/- system. In addition, p53 activity was validated with UV irradiation and siGABARBP. Taken together, our results indicate that GABARBP can regulate the pro-apoptotic activity of cisplatin via the upregulation of p53 expression.
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Affiliation(s)
- Seung Bae Rho
- Research Institute, National Cancer Center, Goyang-si, Gyeonggi-do 410-769, Republic of Korea.
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Re RN, Chen B, Alam J, Cook JL. Reduction of Blood Pressure by AT1 Receptor Decoy Peptides. Ochsner J 2013; 13:33-36. [PMID: 23532469 PMCID: PMC3603185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND We previously identified the binding of the chaperone protein gamma-aminobutyric acid receptor-associated protein (GABARAP) to a sequence on the carboxy-terminus of the angiotensin II AT1 receptor (AT1R) and showed that this binding enhances AT1R trafficking to the cell surface as well as angiotensin signaling. METHODS In this study, we treated sodium-depleted mice with decoy peptides consisting either of a fusion of the cell-penetrating peptide penetratin and the GABARAP/AT1R binding sequence or penetratin fused to a mutated AT1R sequence. We used telemetry to measure blood pressure. RESULTS Systolic and diastolic pressure fell during the 24 hours following decoy peptide injection but not after control peptide injection. Active cell-penetrating decoy peptide decreased 24-hour average systolic blood pressure from 129.8 ± 4.7 mmHg to 125.0 ± 6.0 mmHg (mean ± standard deviation). Diastolic blood pressure fell from 99.0 ± 7.1 mmHg to 95.0 ± 9.2 mmHg (n=5). Administration of the control peptide raised systolic blood pressure from 128.7 ± 1.3 mmHg to 131.7 ± 2.9 mmHg and diastolic pressure from 93.9 ± 4.5 mmHg to 95.9 ± 4.2 mmHg (n=5). The decreases in both systolic and diastolic blood pressure after active peptide administration were statistically significant compared to control peptide administration (P<0.05, two-tailed Wilcoxon rank-sum test). CONCLUSION These results indicate the physiological and potentially therapeutic relevance of inhibitors of GABARAP/AT1R binding.
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Affiliation(s)
| | - Ben Chen
- Institute of Translational Research, Molecular Genetics Laboratory, Ochsner Clinic Foundation
| | - Jawed Alam
- Institute of Translational Research, Molecular Genetics Laboratory, Ochsner Clinic Foundation
- The University of Queensland School of Medicine, Ochsner Clinical School, New Orleans, LA
| | - Julia L. Cook
- Institute of Translational Research, Molecular Genetics Laboratory, Ochsner Clinic Foundation
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Bai R, You W, Chen J, Huang H, Ke C. Molecular cloning and expression analysis of GABA(A) receptor-associated protein (GABARAP) from small abalone, Haliotis diversicolor. FISH & SHELLFISH IMMUNOLOGY 2012; 33:675-682. [PMID: 22771962 DOI: 10.1016/j.fsi.2012.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 04/03/2012] [Accepted: 05/07/2012] [Indexed: 06/01/2023]
Abstract
GABA(A) receptor-associated protein (GABARAP), a multifunctional protein participating in autophagy process, is evolutionarily conserved and involves in innate immunity in eukaryotic cells, but currently there is no research on the relationship between GABARAP and innate immunity in mollusc. In the present study, the GABARAP full-length cDNA and its genomic DNA were firstly cloned from small abalone (Haliotis diversicolor), which was named as saGABARAP. Its full-length cDNA is 963 bp with a 354 bp open reading frame encoding a protein of 117 aa, a 276 bp 5'-UTR, and a 333 bp 3'-UTR including a poly(A) tail, two typical polyadenylation signals (AATAA) and two RNA instability motifs (ATTTA). The deduced protein has an estimated molecular weight of 13.9 kDa and a predicted PI of 8.73. Its genomic DNA comprises 4352 bp, containing three exons and two introns. Quantitative real-time PCR analysis revealed that saGABARAP was constitutively expressed in all examined tissues, with the highest expression level in hepatopancreas, and was upregulated in hepatopancreas and hemocytes after bacterial challenge. In addition, saGABARAP was ubiquitously expressed at all examined embryonic and larval development stages. These results suggested that saGABARAP could respond to bacteria challenge and may play a vital role in the adult innate immune system against pathogens and the development process of abalone embryo and larvae.
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Affiliation(s)
- Rongyao Bai
- Department of Biochemistry and Biotechnology, School of Life Sciences, Xiamen University, Xiamen 361005, China
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15
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Castrop H. Angiotensin receptor-associated proteins: local modulators of the renin–angiotensin system. Pflugers Arch 2012; 465:111-9. [DOI: 10.1007/s00424-012-1113-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 04/30/2012] [Accepted: 05/02/2012] [Indexed: 01/11/2023]
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Vitko JR, Re RN, Alam J, Cook JL. Cell-penetrating peptides corresponding to the angiotensin II Type 1 receptor reduce receptor accumulation and cell surface expression and signaling. Am J Hypertens 2012; 25:24-8. [PMID: 21901015 DOI: 10.1038/ajh.2011.162] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Our previous published studies have established the γ-aminobutyric acid (GABA) receptor-associated protein (GABARAP) as a trafficking protein for the angiotensin II type 1A receptor (AT(1)R). GABARAP overexpression increases both AT(1)R protein accumulation and translocation to the plasma membrane. The present study examined the inhibitory effects of decoy peptides on receptor expression and plasma membrane accumulation. The decoy peptides correspond to the AT(1)R cytoplasmic domain located immediately proximal to the 7th transmembrane domain, a region implicated in GABARAP binding. This competitive binding study was designed as a first step toward evaluating the GABARAP:AT(1)R binding interface as a target for reducing AT(1)R trafficking to the plasma membrane. METHODS AT(1)R and GABARAP plasmids were transfected into mammalian cell lines simultaneously with cell-penetrating peptides (CPPs). CPP-1 and CPP-2 consist of the penetratin (pANT(43-58)) CPP with downstream fusions of GKKFKKYFLQL (AT(1)R) and GKKFEEAFLQL (AT(1)R-mutant) amino acids, respectively. CPP-3 consists of the HIV TAT(48-60) CPP with GKKFKKYFLQL (AT(1)R) fused downstream. Western blotting, signal transduction studies, and 3D deconvolution microscopy experiments were employed. RESULTS Immunoblot analyses and live cell deconvolution microscopy demonstrated that inhibitory (but not control) peptides completely blocked GABARAP-induced intracellular AT(1)R accumulation and cell surface accumulation. GABARAP also stimulated angiotensin II-mediated phospho-ERK1/2 induction by ~ fivefold. This activation was, similarly, quantitatively blocked by the inhibitory peptides. CONCLUSIONS Cell-penetrating decoy peptides which were designed to block the AT(1)R:GABARAP interaction, effectively reduced AT(1)R intracellular accumulation and cell-surface trafficking and signaling. The binding interaction site between AT(1)R and GABARAP represents a potential therapeutic target.
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Chen C, Wang Y, Huang P, Liu-Chen LY. Effects of C-terminal modifications of GEC1 protein and gamma-aminobutyric acid type A (GABA(A)) receptor-associated protein (GABARAP), two microtubule-associated proteins, on kappa opioid receptor expression. J Biol Chem 2011; 286:15106-15. [PMID: 21388957 DOI: 10.1074/jbc.m111.230896] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We demonstrated previously that GEC1, a member of the microtubule-associated protein (MAP) family, bound to the human κ opioid receptor (hKOPR) and promoted hKOPR cell surface expression by facilitating its trafficking along the secretory pathway. GABA(A) receptor-associated protein (GABARAP), a GEC1 analog, also enhanced KOPR expression, but to a lesser extent. The MAP family proteins undergo cleavage of their C-terminal residue(s), and the exposed conserved glycine forms conjugates with phosphatidylethanolamine, which associate with membranes. Here, we examined whether such modifications were required for GEC1 and GABARAP to enhance hKOPR expression. When transiently transfected into CHO or Neuro2A cells, GEC1 and GABARAP were cleaved at the C termini. G116A mutation alone or combined with deletion of Lys(117) in GEC1 (GEC1-A) or Leu(117) in GABARAP (GABARAP-A) blocked their C-terminal cleavage, indicating that the conserved Gly(116) is necessary for C-terminal modification. The two GEC1 mutants enhanced hKOPR expression to similar extents as the wild-type GEC1; however, the two GABARAP mutants did not. Immunofluorescence studies showed that HA-GEC1, HA-GEC1-A, and HA-GABARAP were distributed in a punctate manner and co-localized with KOPR-EGFP in the Golgi apparatus, whereas HA-GABARAP-A did not. Pulldown assay of GST-KOPR-C-tail with HA-GEC1 or HA-GABARAP revealed that GEC1 had stronger association with KOPR-C-tail than GABARAP. These results suggest that because of its stronger binding for hKOPR, GEC1 is able to be recruited by hKOPR sufficiently without membrane association via its C-terminal modification; however, due to its weaker affinity for the hKOPR, GABARAP appears to require C-terminal modifications to enhance KOPR expression.
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Affiliation(s)
- Chongguang Chen
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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Laínez S, Valente P, Ontoria-Oviedo I, Estévez-Herrera J, Camprubí-Robles M, Ferrer-Montiel A, Planells-Cases R. GABAA receptor associated protein (GABARAP) modulates TRPV1 expression and channel function and desensitization. FASEB J 2010; 24:1958-70. [PMID: 20179142 DOI: 10.1096/fj.09-151472] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Transient receptor potential vanilloid (TRPV1) transduces noxious chemical and physical stimuli in high-threshold nociceptors. The pivotal role of TRPV1 in the physiopathology of pain transduction has thrust the identification and characterization of interacting partners that modulate its cellular function. Here, we report that TRPV1 associates with gamma-amino butyric acid A-type (GABA(A)) receptor associated protein (GABARAP) in HEK293 cells and in neurons from dorsal root ganglia coexpressing both proteins. At variance with controls, GABARAP augmented TRPV1 expression in cotransfected cells and stimulated surface receptor clustering. Functionally, GABARAP expression attenuated voltage and capsaicin sensitivity of TRPV1 in the presence of extracellular calcium. Furthermore, the presence of the anchor protein GABARAP notably lengthened the kinetics of vanilloid-induced tachyphylaxia. Notably, the presence of GABARAP selectively increased the interaction of tubulin with the C-terminal domain of TRPV1. Disruption of tubulin cytoskeleton with nocodazole reduced capsaicin-evoked currents in cells expressing TRPV1 and GABARAP, without affecting the kinetics of vanilloid-induced desensitization. Taken together, these findings indicate that GABARAP is an important component of the TRPV1 signaling complex that contributes to increase the channel expression, to traffic and cluster it on the plasma membrane, and to modulate its functional activity at the level of channel gating and desensitization.
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Affiliation(s)
- S Laínez
- Centro de Investigación Príncipe Felipe, Valencia, Spain
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