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  1. Article ; Online: Regulation of Mertk Surface Expression via ADAM17 and γ-Secretase Proteolytic Processing.

    Lahey, Kevin C / Varsanyi, Christopher / Wang, Ziren / Aquib, Ahmed / Gadiyar, Varsha / Rodrigues, Alcina A / Pulica, Rachael / Desind, Samuel / Davra, Viralkumar / Calianese, David C / Liu, Dongfang / Cho, Jong-Hyun / Kotenko, Sergei V / De Lorenzo, Mariana S / Birge, Raymond B

    International journal of molecular sciences

    2024  Volume 25, Issue 8

    Abstract: Mertk, a type I receptor tyrosine kinase and member of the TAM family of receptors, has important functions in promoting efferocytosis and resolving inflammation under physiological conditions. In recent years, Mertk has also been linked to ... ...

    Abstract Mertk, a type I receptor tyrosine kinase and member of the TAM family of receptors, has important functions in promoting efferocytosis and resolving inflammation under physiological conditions. In recent years, Mertk has also been linked to pathophysiological roles in cancer, whereby, in several cancer types, including solid cancers and leukemia/lymphomas. Mertk contributes to oncogenic features of proliferation and cell survival as an oncogenic tyrosine kinase. In addition, Mertk expressed on macrophages, including tumor-associated macrophages, promotes immune evasion in cancer and is suggested to act akin to a myeloid checkpoint inhibitor that skews macrophages towards inhibitory phenotypes that suppress host T-cell anti-tumor immunity. In the present study, to better understand the post-translational regulation mechanisms controlling Mertk expression in monocytes/macrophages, we used a PMA-differentiated THP-1 cell model to interrogate the regulation of Mertk expression and developed a novel Mertk reporter cell line to study the intracellular trafficking of Mertk. We show that PMA treatment potently up-regulates Mertk as well as components of the ectodomain proteolytic processing platform ADAM17, whereas PMA differentially regulates the canonical Mertk ligands Gas6 and Pros1 (Gas6 is down-regulated and Pros1 is up-regulated). Under non-stimulated homeostatic conditions, Mertk in PMA-differentiated THP1 cells shows active constitutive proteolytic cleavage by the sequential activities of ADAM17 and the Presenilin/γ-secretase complex, indicating that Mertk is cleaved homeostatically by the combined sequential action of ADAM17 and γ-secretase, after which the cleaved intracellular fragment of Mertk is degraded in a proteasome-dependent mechanism. Using chimeric Flag-Mertk-EGFP-Myc reporter receptors, we confirm that inhibitors of γ-secretase and MG132, which inhibits the 26S proteasome, stabilize the intracellular fragment of Mertk without evidence of nuclear translocation. Finally, the treatment of cells with active γ-carboxylated Gas6, but not inactive Warfarin-treated non-γ-carboxylated Gas6, regulates a distinct proteolytic itinerary-involved receptor clearance and lysosomal proteolysis. Together, these results indicate that pleotropic and complex proteolytic activities regulate Mertk ectodomain cleavage as a homeostatic negative regulatory event to safeguard against the overactivation of Mertk.
    MeSH term(s) Humans ; c-Mer Tyrosine Kinase/metabolism ; c-Mer Tyrosine Kinase/genetics ; ADAM17 Protein/metabolism ; ADAM17 Protein/genetics ; Amyloid Precursor Protein Secretases/metabolism ; Amyloid Precursor Protein Secretases/genetics ; Proteolysis ; Intercellular Signaling Peptides and Proteins/metabolism ; THP-1 Cells ; Macrophages/metabolism ; Protein S/metabolism ; Monocytes/metabolism ; Tetradecanoylphorbol Acetate/pharmacology
    Chemical Substances c-Mer Tyrosine Kinase (EC 2.7.10.1) ; ADAM17 Protein (EC 3.4.24.86) ; Amyloid Precursor Protein Secretases (EC 3.4.-) ; MERTK protein, human (EC 2.7.10.1) ; ADAM17 protein, human (EC 3.4.24.86) ; growth arrest-specific protein 6 ; Intercellular Signaling Peptides and Proteins ; PROS1 protein, human ; Protein S ; Tetradecanoylphorbol Acetate (NI40JAQ945)
    Language English
    Publishing date 2024-04-17
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms25084404
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Connexin-43 reduction prevents muscle defects in a mouse model of manifesting Duchenne muscular dystrophy female carriers.

    Nouet, Julie / Himelman, Eric / Lahey, Kevin C / Zhao, Qingshi / Fraidenraich, Diego

    Scientific reports

    2020  Volume 10, Issue 1, Page(s) 5683

    Abstract: Duchenne muscular dystrophy (DMD) is a severe X-linked neuromuscular disorder that affects males. However, 8% of female carriers are symptomatic and underrepresented in research due to the lack of animal models. We generated a symptomatic mouse model of ... ...

    Abstract Duchenne muscular dystrophy (DMD) is a severe X-linked neuromuscular disorder that affects males. However, 8% of female carriers are symptomatic and underrepresented in research due to the lack of animal models. We generated a symptomatic mouse model of DMD carriers via injection of mdx (murine DMD) embryonic stem cells (ESCs) into wild-type (WT) blastocysts (mdx/WT chimera). mdx/WT chimeras developed cardiomyopathic features and dystrophic skeletal muscle phenotypes including elevated mononuclear invasion, central nucleation, fibrosis and declined forelimb grip strength. The disease was accompanied by connexin-43 (Cx43) aberrantly enhanced in both cardiac and skeletal muscles and remodeled in the heart. Genetic reduction of Cx43-copy number in mdx/WT-Cx43(+/-) chimeras protected them from both cardiac and skeletal muscle fiber damage. In dystrophic skeletal muscle, Cx43 expression was not seen in the fibers but in adjacent F4/80+ mononuclear cells. Ethidium Bromide uptake in purified F4/80+/CD11b+ mdx macrophages revealed functional activity of Cx43, which was inhibited by administration of Gap19 peptide mimetic, a Cx43 hemichannel-specific inhibitor. Thus, we suggest that Cx43 reduction in symptomatic DMD carrier mice leads to prevention of Cx43 remodeling in the heart and prevention of aberrant Cx43 hemichannel activity in the skeletal muscle macrophages neighboring Cx43 non-expressing fibers.
    MeSH term(s) Animals ; Cardiomyopathies/metabolism ; Connexin 43/genetics ; Connexin 43/metabolism ; Disease Models, Animal ; Dystrophin/genetics ; Female ; Heart/physiopathology ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Inbred mdx ; Muscle Fibers, Skeletal/metabolism ; Muscle Strength ; Muscle, Skeletal/metabolism ; Muscular Dystrophy, Animal/metabolism ; Muscular Dystrophy, Duchenne/genetics ; Muscular Dystrophy, Duchenne/physiopathology
    Chemical Substances Connexin 43 ; Dystrophin ; GJA1 protein, mouse
    Language English
    Publishing date 2020-03-30
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-020-62844-9
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Mertk: An emerging target in cancer biology and immuno-oncology.

    Lahey, Kevin C / Gadiyar, Varsha / Hill, Amanda / Desind, Samuel / Wang, Ziren / Davra, Viralkumar / Patel, Radhey / Zaman, Ahnaf / Calianese, David / Birge, Raymond B

    International review of cell and molecular biology

    2022  Volume 368, Page(s) 35–59

    Abstract: Mertk, a type I Receptor Tyrosine Kinase (RTK) and member of the TAM (Tyro3, Axl, and Mertk) family of homologous tyrosine kinases, has important roles in signal transduction both homeostatically on normal cells as well as patho-physiologically on both ... ...

    Abstract Mertk, a type I Receptor Tyrosine Kinase (RTK) and member of the TAM (Tyro3, Axl, and Mertk) family of homologous tyrosine kinases, has important roles in signal transduction both homeostatically on normal cells as well as patho-physiologically on both tumor-associated macrophages and malignant cells by its overexpression in a wide array of cancers. The main ligands of Mertk are Vitamin K-modified endogenous proteins Gas6 and Protein S (ProS1), heterobifunctional modular proteins that bind Mertk via two carboxyl-terminal laminin-like globular (LG) domains, and an N-terminal Gla domain that binds anionic phospholipids, whereby externalized phosphatidylserine (PS) on stressed viable and caspase-activated apoptotic cells is most emblematic. Recent studies indicate that Vitamin K-dependent γ-carboxylation on the N-terminal Gla domain of Gas6 and Protein S is necessary for PS binding and Mertk activation, implying that Mertk is preferentially active in tissues where there is high externalized PS, such as the tumor microenvironment (TME) and acute virally infected tissues. Once stimulated, activated Mertk can provide a survival advantage for cancer cells as well as drive compensatory proliferation. On monocytes and tumor-associated macrophages, Mertk promotes efferocytosis and acts as an inhibitory receptor that impairs host anti-tumor immunity, functioning akin to a myeloid checkpoint inhibitor. In recent years, inhibition of Mertk has been implicated in a dual role to enhance the sensitivity of cancer cells to cytotoxic agents along with improving host anti-tumor immunity with anti-PD-1/PD-L1 immunotherapy. Here, we examine the rationale of Mertk-targeted immunotherapies, the current and potential therapeutic strategies, the clinical status of Mertk-specific therapies, and potential challenges and obstacles for Mertk-focused therapies.
    MeSH term(s) Biology ; Humans ; Neoplasms/therapy ; Protein S ; Proto-Oncogene Proteins/metabolism ; Tumor Microenvironment ; Vitamin K ; c-Mer Tyrosine Kinase/metabolism
    Chemical Substances Protein S ; Proto-Oncogene Proteins ; Vitamin K (12001-79-5) ; MERTK protein, human (EC 2.7.10.1) ; c-Mer Tyrosine Kinase (EC 2.7.10.1)
    Language English
    Publishing date 2022-05-05
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 2427220-6
    ISSN 1937-6448 ; 0074-7696
    ISSN 1937-6448 ; 0074-7696
    DOI 10.1016/bs.ircmb.2022.04.004
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Cell Death in the Tumor Microenvironment: Implications for Cancer Immunotherapy.

    Gadiyar, Varsha / Lahey, Kevin C / Calianese, David / Devoe, Connor / Mehta, Dhriti / Bono, Kristy / Desind, Samuel / Davra, Viralkumar / Birge, Raymond B

    Cells

    2020  Volume 9, Issue 10

    Abstract: The physiological fate of cells that die by apoptosis is their prompt and efficient removal by efferocytosis. During these processes, apoptotic cells release intracellular constituents that include purine nucleotides, lysophosphatidylcholine (LPC), and ... ...

    Abstract The physiological fate of cells that die by apoptosis is their prompt and efficient removal by efferocytosis. During these processes, apoptotic cells release intracellular constituents that include purine nucleotides, lysophosphatidylcholine (LPC), and Sphingosine-1-phosphate (S1P) that induce migration and chemo-attraction of phagocytes as well as mitogens and extracellular membrane-bound vesicles that contribute to apoptosis-induced compensatory proliferation and alteration of the extracellular matrix and the vascular network. Additionally, during efferocytosis, phagocytic cells produce a number of anti-inflammatory and resolving factors, and, together with apoptotic cells, efferocytic events have a homeostatic function that regulates tissue repair. These homeostatic functions are dysregulated in cancers, where, aforementioned events, if not properly controlled, can lead to cancer progression and immune escape. Here, we summarize evidence that apoptosis and efferocytosis are exploited in cancer, as well as discuss current translation and clinical efforts to harness signals from dying cells into therapeutic strategies.
    MeSH term(s) Apoptosis/drug effects ; Apoptosis/immunology ; Apoptosis/physiology ; Caspases/metabolism ; Cell Death/drug effects ; Cell Death/immunology ; Humans ; Lysophosphatidylcholines/metabolism ; Lysophospholipids/metabolism ; Molecular Targeted Therapy/methods ; Neoplasms/drug therapy ; Neoplasms/immunology ; Neoplasms/pathology ; Phagocytosis/genetics ; Phagocytosis/immunology ; Phosphatidylserines/metabolism ; Purine Nucleotides/metabolism ; Sphingosine/analogs & derivatives ; Sphingosine/metabolism ; Tumor Escape ; Tumor Microenvironment/immunology
    Chemical Substances Lysophosphatidylcholines ; Lysophospholipids ; Phosphatidylserines ; Purine Nucleotides ; sphingosine 1-phosphate (26993-30-6) ; Caspases (EC 3.4.22.-) ; Sphingosine (NGZ37HRE42)
    Language English
    Publishing date 2020-09-29
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2661518-6
    ISSN 2073-4409 ; 2073-4409
    ISSN (online) 2073-4409
    ISSN 2073-4409
    DOI 10.3390/cells9102207
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Phosphatidylserine-Targeting Monoclonal Antibodies Exhibit Distinct Biochemical and Cellular Effects on Anti-CD3/CD28-Stimulated T Cell IFN-γ and TNF-α Production.

    Calianese, David / Kreiss, Tamara / Kasikara, Canan / Davra, Viralkumar / Lahey, Kevin C / Gadiyar, Varsha / Geng, Ke / Singh, Sukhwinder / Honnen, William / Jaijyan, Dabbu Kumar / Reichman, Charles / Siekierka, John / Gennaro, Maria Laura / Kotenko, Sergei V / Ucker, David S / Brekken, Rolf A / Pinter, Abraham / Birge, Raymond B / Choudhary, Alok

    Journal of immunology (Baltimore, Md. : 1950)

    2021  Volume 207, Issue 2, Page(s) 436–448

    Abstract: Phosphatidylserine (PS)-targeting monoclonal Abs (mAbs) that directly target PS and target PS via β2-gp1 (β2GP1) have been in preclinical and clinical development for over 10 y for the treatment of infectious diseases and cancer. Although the intended ... ...

    Abstract Phosphatidylserine (PS)-targeting monoclonal Abs (mAbs) that directly target PS and target PS via β2-gp1 (β2GP1) have been in preclinical and clinical development for over 10 y for the treatment of infectious diseases and cancer. Although the intended targets of PS-binding mAbs have traditionally included pathogens as well as stressed tumor cells and its associated vasculature in oncology, the effects of PS-targeting mAbs on activated immune cells, notably T cells, which externalize PS upon Ag stimulation, is not well understood. Using human T cells from healthy donor PBMCs activated with an anti-CD3 + anti-CD28 Ab mixture (anti-CD3/CD28) as a model for TCR-mediated PS externalization and T cell stimulation, we investigated effects of two different PS-targeting mAbs, 11.31 and bavituximab (Bavi), on TCR activation and TCR-mediated cytokine production in an ex vivo paradigm. Although 11.31 and Bavi bind selectivity to anti-CD3/28 activated T cells in a PS-dependent manner, surprisingly, they display distinct functional activities in their effect on IFN-γ and TNF-ɑ production, whereby 11.31, but not Bavi, suppressed cytokine production. This inhibitory effect on anti-CD3/28 activated T cells was observed on both CD4
    MeSH term(s) Antibodies, Monoclonal/immunology ; CD28 Antigens/immunology ; CD3 Complex/immunology ; CD4-Positive T-Lymphocytes/immunology ; CD8-Positive T-Lymphocytes/immunology ; Cell Line ; HEK293 Cells ; Humans ; Interferon-gamma/immunology ; Leukocytes, Mononuclear/immunology ; Lymphocyte Activation/immunology ; Muromonab-CD3/immunology ; Phosphatidylserines/immunology ; Tumor Necrosis Factor-alpha/immunology
    Chemical Substances Antibodies, Monoclonal ; CD28 Antigens ; CD3 Complex ; Muromonab-CD3 ; Phosphatidylserines ; Tumor Necrosis Factor-alpha ; Interferon-gamma (82115-62-6) ; bavituximab (Q16CT95N25)
    Language English
    Publishing date 2021-07-02
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3056-9
    ISSN 1550-6606 ; 0022-1767 ; 1048-3233 ; 1047-7381
    ISSN (online) 1550-6606
    ISSN 0022-1767 ; 1048-3233 ; 1047-7381
    DOI 10.4049/jimmunol.2000763
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Axl and Mertk Receptors Cooperate to Promote Breast Cancer Progression by Combined Oncogenic Signaling and Evasion of Host Antitumor Immunity.

    Davra, Viralkumar / Kumar, Sushil / Geng, Ke / Calianese, David / Mehta, Dhriti / Gadiyar, Varsha / Kasikara, Canan / Lahey, Kevin C / Chang, Yun-Juan / Wichroski, Michael / Gao, Chan / De Lorenzo, Mariana S / Kotenko, Sergei V / Bergsbaken, Tessa / Mishra, Pankaj K / Gause, William C / Quigley, Michael / Spires, Thomas E / Birge, Raymond B

    Cancer research

    2020  Volume 81, Issue 3, Page(s) 698–712

    Abstract: Despite the promising clinical benefit of targeted and immune checkpoint blocking therapeutics, current strategies have limited success in breast cancer, indicating that additional inhibitory pathways are required to complement existing therapeutics. TAM ...

    Abstract Despite the promising clinical benefit of targeted and immune checkpoint blocking therapeutics, current strategies have limited success in breast cancer, indicating that additional inhibitory pathways are required to complement existing therapeutics. TAM receptors (Tyro-3, Axl, and Mertk) are often correlated with poor prognosis because of their capacities to sustain an immunosuppressive environment. Here, we ablate Axl on tumor cells using CRISPR/Cas9 gene editing, and by targeting Mertk in the tumor microenvironment (TME), we observed distinct functions of TAM as oncogenic kinases, as well as inhibitory immune receptors. Depletion of Axl suppressed cell intrinsic oncogenic properties, decreased tumor growth, reduced the incidence of lung metastasis and increased overall survival of mice when injected into mammary fat pad of syngeneic mice, and demonstrated synergy when combined with anti-PD-1 therapy. Blockade of Mertk function on macrophages decreased efferocytosis, altered the cytokine milieu, and resulted in suppressed macrophage gene expression patterns. Mertk-knockout mice or treatment with anti-Mertk-neutralizing mAb also altered the cellular immune profile, resulting in a more inflamed tumor environment with enhanced T-cell infiltration into tumors and T-cell-mediated cytotoxicity. The antitumor activity from Mertk inhibition was abrogated by depletion of cytotoxic CD8α T cells by using anti-CD8α mAb or by transplantation of tumor cells into B6.CB17-Prkdc SCID mice. Our data indicate that targeting Axl expressed on tumor cells and Mertk in the TME is predicted to have a combinatorial benefit to enhance current immunotherapies and that Axl and Mertk have distinct functional activities that impair host antitumor response. SIGNIFICANCE: This study demonstrates how TAM receptors act both as oncogenic tyrosine kinases and as receptors that mediate immune evasion in cancer progression.
    MeSH term(s) Animals ; Cell Line, Tumor ; Cells, Cultured ; Female ; Gene Expression Regulation, Neoplastic/immunology ; Humans ; Immune Evasion/genetics ; Immune Evasion/immunology ; Immunotherapy/methods ; Kaplan-Meier Estimate ; Mammary Neoplasms, Experimental/genetics ; Mammary Neoplasms, Experimental/immunology ; Mammary Neoplasms, Experimental/therapy ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mice, Knockout ; Mice, SCID ; Proto-Oncogene Proteins/genetics ; Proto-Oncogene Proteins/immunology ; Proto-Oncogene Proteins/metabolism ; Receptor Protein-Tyrosine Kinases/genetics ; Receptor Protein-Tyrosine Kinases/immunology ; Receptor Protein-Tyrosine Kinases/metabolism ; Signal Transduction/genetics ; Signal Transduction/immunology ; c-Mer Tyrosine Kinase/genetics ; c-Mer Tyrosine Kinase/immunology ; c-Mer Tyrosine Kinase/metabolism ; Axl Receptor Tyrosine Kinase ; Mice
    Chemical Substances Proto-Oncogene Proteins ; Mertk protein, mouse (EC 2.7.10.1) ; Receptor Protein-Tyrosine Kinases (EC 2.7.10.1) ; c-Mer Tyrosine Kinase (EC 2.7.10.1) ; Axl Receptor Tyrosine Kinase
    Language English
    Publishing date 2020-11-25
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1432-1
    ISSN 1538-7445 ; 0008-5472
    ISSN (online) 1538-7445
    ISSN 0008-5472
    DOI 10.1158/0008-5472.CAN-20-2066
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Small Fractions of Muscular Dystrophy Embryonic Stem Cells Yield Severe Cardiac and Skeletal Muscle Defects in Adult Mouse Chimeras.

    Gonzalez, J Patrick / Kyrychenko, Sergii / Kyrychenko, Viktoriia / Schneider, Joel S / Granier, Celine J / Himelman, Eric / Lahey, Kevin C / Zhao, Qingshi / Yehia, Ghassan / Tao, Yuan-Xiang / Bhaumik, Mantu / Shirokova, Natalia / Fraidenraich, Diego

    Stem cells (Dayton, Ohio)

    2017  Volume 35, Issue 3, Page(s) 597–610

    Abstract: Duchenne muscular dystrophy (DMD) is characterized by the loss of the protein dystrophin, leading to muscle fragility, progressive weakening, and susceptibility to mechanical stress. Although dystrophin-negative mdx mouse models have classically been ... ...

    Abstract Duchenne muscular dystrophy (DMD) is characterized by the loss of the protein dystrophin, leading to muscle fragility, progressive weakening, and susceptibility to mechanical stress. Although dystrophin-negative mdx mouse models have classically been used to study DMD, phenotypes appear mild compared to patients. As a result, characterization of muscle pathology, especially in the heart, has proven difficult. We report that injection of mdx embryonic stem cells (ESCs) into Wild Type blastocysts produces adult mouse chimeras with severe DMD phenotypes in the heart and skeletal muscle. Inflammation, regeneration and fibrosis are observed at the whole organ level, both in dystrophin-negative and dystrophin-positive portions of the chimeric tissues. Skeletal and cardiac muscle function are also decreased to mdx levels. In contrast to mdx heterozygous carriers, which show no significant phenotypes, these effects are even observed in chimeras with low levels of mdx ESC incorporation (10%-30%). Chimeric mice lack typical compensatory utrophin upregulation, and show pathological remodeling of Connexin-43. In addition, dystrophin-negative and dystrophin-positive isolated cardiomyocytes show augmented calcium response to mechanical stress, similar to mdx cells. These global effects highlight a novel role of mdx ESCs in triggering muscular dystrophy even when only low amounts are present. Stem Cells 2017;35:597-610.
    Language English
    Publishing date 2017-03
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1143556-2
    ISSN 1549-4918 ; 1066-5099
    ISSN (online) 1549-4918
    ISSN 1066-5099
    DOI 10.1002/stem.2518
    Database MEDical Literature Analysis and Retrieval System OnLINE

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