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  1. Article ; Online: Myeloid-CITED2 Deficiency Exacerbates Diet-Induced Obesity and Pro-Inflammatory Macrophage Response.

    Zafar, Atif / Ng, Hang Pong / Chan, E Ricky / Dunwoodie, Sally L / Mahabeleshwar, Ganapati H

    Cells

    2023  Volume 12, Issue 17

    Abstract: Macrophages are the principal component of the innate immune system that are found in all tissues and play an essential role in development, homeostasis, tissue repair, and immunity. Clinical and experimental studies have shown that transcriptionally ... ...

    Abstract Macrophages are the principal component of the innate immune system that are found in all tissues and play an essential role in development, homeostasis, tissue repair, and immunity. Clinical and experimental studies have shown that transcriptionally dynamic pro-inflammatory macrophages are involved in the pathogenesis of diet-induced obesity and insulin resistance. However, cell-intrinsic mechanisms must exist that bridle uncontrolled pro-inflammatory macrophage activation in metabolic organs and disease pathogenesis. In this study, we show that CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2) is an essential negative regulator of pro-inflammatory macrophage activation and inflammatory disease pathogenesis. Our in vivo studies show that myeloid-CITED2 deficiency significantly elevates high-fat diet (HFD)-induced expansion of adipose tissue volume, obesity, glucose intolerance, and insulin resistance. Moreover, myeloid-CITED2 deficiency also substantially augments HFD-induced adipose tissue inflammation and adverse remodeling of adipocytes. Our integrated transcriptomics and gene set enrichment analyses show that CITED2 deficiency curtails BCL6 signaling and broadly elevates BCL6-repressive gene target expression in macrophages. Using complementary gain- and loss-of-function studies, we found that CITED2 deficiency attenuates, and CITED2 overexpression elevates, inducible BCL6 expression in macrophages. At the molecular level, our analyses show that CITED2 promotes BCL6 expression by restraining STAT5 activation in macrophages. Interestingly, siRNA-mediated knockdown of STAT5 fully reversed elevated pro-inflammatory gene target expression in CITED2-deficient macrophages. Overall, our findings highlight that CITED2 restrains inflammation by promoting BCL6 expression in macrophages, and limits diet-induced obesity and insulin resistance.
    MeSH term(s) Diet, High-Fat/adverse effects ; Inflammation ; Insulin Resistance ; Macrophages ; Obesity ; Repressor Proteins/genetics ; STAT5 Transcription Factor ; Trans-Activators/genetics ; Animals
    Chemical Substances Repressor Proteins ; STAT5 Transcription Factor ; Trans-Activators
    Language English
    Publishing date 2023-08-24
    Publishing country Switzerland
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2661518-6
    ISSN 2073-4409 ; 2073-4409
    ISSN (online) 2073-4409
    ISSN 2073-4409
    DOI 10.3390/cells12172136
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Macrophage-Hypoxia-Inducible Factor-1α Signaling in Carotid Artery Stenosis.

    Kim, Gun-Dong / Ng, Hang Pong / Chan, E Ricky / Mahabeleshwar, Ganapati H

    The American journal of pathology

    2021  Volume 191, Issue 6, Page(s) 1118–1134

    Abstract: Macrophages play crucial and diverse roles in the pathogenesis of inflammatory vascular diseases. Macrophages are the principal innate immune cells recruited to arterial walls to govern vascular homeostasis by modulating the proliferation of vascular ... ...

    Abstract Macrophages play crucial and diverse roles in the pathogenesis of inflammatory vascular diseases. Macrophages are the principal innate immune cells recruited to arterial walls to govern vascular homeostasis by modulating the proliferation of vascular smooth muscle cells, the reorganization of extracellular matrix components, the elimination of dead cells, and the restoration of normal blood flow. However, chronic sterile inflammation within the arterial walls draws inflammatory macrophages into intimal/neointimal regions that may contribute to disease pathogenesis. In this context, the accumulation and aberrant activation of macrophages in the neointimal regions govern the progression of inflammatory arterial wall diseases. Herein, we report that myeloid-hypoxia-inducible factor-1α (HIF1α) deficiency attenuates vascular smooth muscle cells and macrophage abundance in stenotic arteries and abrogates carotid neointima formation in vivo. The integrated transcriptomics, Gene Set Enrichment Analysis, metabolomics, and target gene evaluation showed that HIF1α represses oxidative phosphorylation, tricarboxylic acid cycle, fatty acid metabolism, and c-MYC signaling pathways while promoting inflammatory, glycolytic, hypoxia response gene expression in stenotic artery macrophages. At the molecular level, proinflammatory agents utilized STAT3 signaling pathways to elevate HIF1α expression in macrophages. Collectively, this study uncovers that macrophage-HIF1α deficiency restrains the pathogenesis of carotid artery stenosis by rewiring inflammatory and metabolic signaling pathways in macrophages.
    MeSH term(s) Animals ; Carotid Stenosis/metabolism ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism ; Macrophages/metabolism ; Mice ; Mice, Inbred C57BL ; Signal Transduction/physiology
    Chemical Substances Hypoxia-Inducible Factor 1, alpha Subunit
    Language English
    Publishing date 2021-03-19
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2943-9
    ISSN 1525-2191 ; 0002-9440
    ISSN (online) 1525-2191
    ISSN 0002-9440
    DOI 10.1016/j.ajpath.2021.03.008
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: MSCs mediate long-term efficacy in a Crohn's disease model by sustained anti-inflammatory macrophage programming via efferocytosis.

    Dave, Maneesh / Dev, Atul / Somoza, Rodrigo A / Zhao, Nan / Viswanath, Satish / Mina, Pooja Rani / Chirra, Prathyush / Obmann, Verena Carola / Mahabeleshwar, Ganapati H / Menghini, Paola / Durbin-Johnson, Blythe / Nolta, Jan / Soto, Christopher / Osme, Abdullah / Khuat, Lam T / Murphy, William J / Caplan, Arnold I / Cominelli, Fabio

    NPJ Regenerative medicine

    2024  Volume 9, Issue 1, Page(s) 6

    Abstract: Mesenchymal stem cells (MSCs) are novel therapeutics for the treatment of Crohn's disease. However, their mechanism of action is unclear, especially in disease-relevant chronic models of inflammation. Thus, we used SAMP-1/YitFc (SAMP), a chronic and ... ...

    Abstract Mesenchymal stem cells (MSCs) are novel therapeutics for the treatment of Crohn's disease. However, their mechanism of action is unclear, especially in disease-relevant chronic models of inflammation. Thus, we used SAMP-1/YitFc (SAMP), a chronic and spontaneous murine model of small intestinal inflammation, to study the therapeutic effects and mechanism of action of human bone marrow-derived MSCs (hMSC). hMSC dose-dependently inhibited naïve T lymphocyte proliferation via prostaglandin E
    Language English
    Publishing date 2024-01-20
    Publishing country United States
    Document type Journal Article
    ISSN 2057-3995
    ISSN (online) 2057-3995
    DOI 10.1038/s41536-024-00347-1
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Kruppel-like factor 6 promotes macrophage inflammatory and hypoxia response.

    Kim, Gun-Dong / Ng, Hang Pong / Chan, E Ricky / Mahabeleshwar, Ganapati H

    FASEB journal : official publication of the Federation of American Societies for Experimental Biology

    2020  Volume 34, Issue 2, Page(s) 3209–3223

    Abstract: Macrophages are the professional phagocytes that protect the host from infection or injury. Tissue microenvironment at the site of injury and inflammation is characterized by low oxygen concentration and poor supply of nutrients. The responding ... ...

    Abstract Macrophages are the professional phagocytes that protect the host from infection or injury. Tissue microenvironment at the site of injury and inflammation is characterized by low oxygen concentration and poor supply of nutrients. The responding macrophages have to advance against oxygen and nutrient gradients to reach the site of inflammation to perform host protection, and tissue repair functions. Thus, evolution has fashioned macrophages to orchestrate a coordinated inflammatory and hypoxic gene program to mount an effective immune response. Here, we discovered that Kruppel-like factor 6 (KLF6) governs macrophage functions by promoting inflammatory and hypoxic response gene programming. Our in vivo studies revealed that myeloid-KLF6-deficient mice were highly resistant to endotoxin-induced systemic inflammatory response syndrome symptomatology and mortality. Using complementary gain- and loss-of-function studies, we observed that KLF6 overexpression elevate and KLF6 deficiency attenuate inducible HIF1α expression in macrophages. Our integrated transcriptomics and gene set enrichment analysis studies uncovered that KLF6 deficiency attenuates broad inflammatory and glycolytic gene expression in macrophages. More importantly, overexpression of oxygen stable HIF1α reversed attenuated proinflammatory and glycolytic gene expression in KLF6-deficient macrophages. Collectively, our studies uncovered that KLF6 govern inflammatory and hypoxic response by regulating HIF1α expression in macrophage.
    MeSH term(s) Animals ; Cell Hypoxia ; Cells, Cultured ; Cytokines/genetics ; Cytokines/metabolism ; Glycolysis ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism ; Kruppel-Like Factor 6/genetics ; Kruppel-Like Factor 6/metabolism ; Mice ; Mice, Inbred C57BL ; RAW 264.7 Cells ; Transcriptome
    Chemical Substances Cytokines ; Hif1a protein, mouse ; Hypoxia-Inducible Factor 1, alpha Subunit ; Klf6 protein, mouse ; Kruppel-Like Factor 6
    Language English
    Publishing date 2020-01-06
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 639186-2
    ISSN 1530-6860 ; 0892-6638
    ISSN (online) 1530-6860
    ISSN 0892-6638
    DOI 10.1096/fj.201902221R
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: BHLHE40 promotes macrophage pro-inflammatory gene expression and functions.

    Zafar, Atif / Ng, Hang Pong / Kim, Gun-Dong / Chan, E Ricky / Mahabeleshwar, Ganapati H

    FASEB journal : official publication of the Federation of American Societies for Experimental Biology

    2021  Volume 35, Issue 10, Page(s) e21940

    Abstract: Macrophages are the principal innate immune cells that populate all major organs and provide the first line of cellular defense against infections and/or injuries. The immediate and early-responding macrophages must mount a robust pro-inflammatory ... ...

    Abstract Macrophages are the principal innate immune cells that populate all major organs and provide the first line of cellular defense against infections and/or injuries. The immediate and early-responding macrophages must mount a robust pro-inflammatory response to protect the host by eliminating deleterious agents. The effective pro-inflammatory macrophage response requires the activation of complex transcriptional programs that modulate the dynamic regulation of inflammatory and metabolic gene expression. Therefore, transcription factors that govern pro-inflammatory and metabolic gene expression play an essential role in shaping the macrophage inflammatory response. Herein, we identify the basic helix-loop-helix family member e40 (BHLHE40), as a critical transcription factor that promotes broad pro-inflammatory and glycolytic gene expression by elevating HIF1α levels in macrophages. Our in vivo studies revealed that myeloid-BHLHE40 deficiency significantly attenuates macrophage and neutrophil recruitment to the site of inflammation. Our integrated transcriptomics and gene set enrichment analysis (GSEA) studies show that BHLHE40 deficiency broadly curtails inflammatory signaling pathways, hypoxia response, and glycolytic gene expression in macrophages. Utilizing complementary gain- and loss-of-function studies, our analyses uncovered that BHLHE40 promotes LPS-induced HIF1α mRNA and protein expression in macrophages. More importantly, forced overexpression of oxygen stable form of HIF1α completely reversed attenuated pro-inflammatory and glycolytic gene expression in BHLHE40-deficient macrophages. Collectively, these results demonstrate that BHLHE40 promotes macrophage pro-inflammatory gene expression and functions by elevating HIF1α expression in macrophages.
    MeSH term(s) Animals ; Basic Helix-Loop-Helix Transcription Factors/deficiency ; Basic Helix-Loop-Helix Transcription Factors/metabolism ; Blood Cells/metabolism ; Female ; Gene Expression Regulation ; Glycolysis/drug effects ; Glycolysis/genetics ; Homeodomain Proteins/metabolism ; Hypoxia-Inducible Factor 1, alpha Subunit/metabolism ; Inflammation/chemically induced ; Inflammation/genetics ; Lipopolysaccharides/pharmacology ; Lung/drug effects ; Lung/pathology ; Macrophages/metabolism ; Male ; Mice ; Protective Agents ; Zymosan/adverse effects ; Zymosan/antagonists & inhibitors
    Chemical Substances Basic Helix-Loop-Helix Transcription Factors ; Bhlhe40 protein, mouse ; Hif1a protein, mouse ; Homeodomain Proteins ; Hypoxia-Inducible Factor 1, alpha Subunit ; Lipopolysaccharides ; Protective Agents ; Zymosan (9010-72-4)
    Language English
    Publishing date 2021-09-22
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 639186-2
    ISSN 1530-6860 ; 0892-6638
    ISSN (online) 1530-6860
    ISSN 0892-6638
    DOI 10.1096/fj.202100944R
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Kruppel-like factor 6 and miR-223 signaling axis regulates macrophage-mediated inflammation.

    Kim, Gun-Dong / Ng, Hang Pong / Patel, Nibedita / Mahabeleshwar, Ganapati H

    FASEB journal : official publication of the Federation of American Societies for Experimental Biology

    2019  Volume 33, Issue 10, Page(s) 10902–10915

    Abstract: Macrophage-mediated inflammation is an explicitly robust biologic response that plays a critical role in maintaining tissue homeostasis by eliminating deleterious agents. These tissue macrophages tailor appropriate responses to external cues by altering ... ...

    Abstract Macrophage-mediated inflammation is an explicitly robust biologic response that plays a critical role in maintaining tissue homeostasis by eliminating deleterious agents. These tissue macrophages tailor appropriate responses to external cues by altering inflammatory gene expression. Therefore, transcription factors and regulators that modulate inflammatory gene expression play an essential role in shaping the macrophage inflammatory response. Here, we identify that Kruppel-like factor (KLF)6 promotes inflammation by restraining microRNA-223 (miR-223) expression in macrophages. We uncovered that pro- and anti-inflammatory agents oppositely regulate KLF6 and miR-223 expression in macrophages. Using complementary gain- and loss-of-function studies, we observed that overexpression of KLF6 attenuates and deficiency of KLF6 elevates miR-223 expression in macrophages. Furthermore, heightened miR-223 expression in KLF6-deficient macrophages significantly attenuates inducible proinflammatory gene expression. Concordantly, myeloid-
    MeSH term(s) Adipose Tissue/metabolism ; Adipose Tissue/pathology ; Animals ; Cells, Cultured ; Female ; Humans ; Immunity, Innate ; Kruppel-Like Factor 6/genetics ; Kruppel-Like Factor 6/metabolism ; Macrophages/immunology ; Male ; Mice ; Mice, Inbred C57BL ; MicroRNAs/genetics ; MicroRNAs/metabolism ; Obesity/metabolism ; RAW 264.7 Cells ; Signal Transduction
    Chemical Substances Klf6 protein, mouse ; Kruppel-Like Factor 6 ; MIRN223 microRNA, mouse ; MicroRNAs
    Language English
    Publishing date 2019-06-29
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 639186-2
    ISSN 1530-6860 ; 0892-6638
    ISSN (online) 1530-6860
    ISSN 0892-6638
    DOI 10.1096/fj.201900867RR
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: CITED2 limits pathogenic inflammatory gene programs in myeloid cells.

    Pong Ng, Hang / Kim, Gun-Dong / Ricky Chan, E / Dunwoodie, Sally L / Mahabeleshwar, Ganapati H

    FASEB journal : official publication of the Federation of American Societies for Experimental Biology

    2020  Volume 34, Issue 9, Page(s) 12100–12113

    Abstract: Monocyte-derived macrophages are the major innate immune cells that provide the first line of cellular defense against infections or injuries. These recruited macrophages at the site of inflammation are exposed to a broad range of cytokines that ... ...

    Abstract Monocyte-derived macrophages are the major innate immune cells that provide the first line of cellular defense against infections or injuries. These recruited macrophages at the site of inflammation are exposed to a broad range of cytokines that categorically incite a robust pro-inflammatory response. However, macrophage pro-inflammatory activation must be under exquisite control to avert unbridled inflammation. Thus, endogenous mechanisms must exist that rigorously preserve macrophage quiescence and yet, allow nimble pro-inflammatory macrophage response with precise spatiotemporal control. Herein, we identify the CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2) as a critical intrinsic negative regulator of inflammation, which broadly attenuates pro-inflammatory gene programs in macrophages. Our in vivo studies revealed that myeloid-CITED2 deficiency significantly heightened macrophages and neutrophils recruitment to the site of inflammation. Our integrated transcriptomics and gene set enrichment analysis (GSEA) studies uncovered that CITED2 deficiency broadly enhances NFκB targets, IFNγ/IFNα responses, and inflammatory response gene expression in macrophages. Using complementary gain- and loss-of-function studies, we observed that CITED2 overexpression attenuate and CITED2 deficiency elevate LPS-induced NFκB transcriptional activity and NFκB-p65 recruitment to target gene promoter in macrophages. More importantly, blockade of NFκB signaling completely reversed elevated pro-inflammatory gene expression in macrophages. Collectively, our findings show that CITED2 restrains NFκB activation and curtails broad pro-inflammatory gene programs in myeloid cells.
    MeSH term(s) Animals ; Gene Expression Regulation ; Inflammation/chemically induced ; Inflammation/genetics ; Inflammation/metabolism ; Inflammation/pathology ; Lipopolysaccharides/toxicity ; Macrophages/metabolism ; Macrophages/pathology ; Mice ; Neutrophils/metabolism ; Neutrophils/pathology ; RAW 264.7 Cells ; Repressor Proteins/genetics ; Repressor Proteins/metabolism ; Trans-Activators/genetics ; Trans-Activators/metabolism ; Transcription Factor RelA/genetics ; Transcription Factor RelA/metabolism ; Transcription, Genetic
    Chemical Substances Cited2 protein, mouse ; Lipopolysaccharides ; Rela protein, mouse ; Repressor Proteins ; Trans-Activators ; Transcription Factor RelA
    Language English
    Publishing date 2020-07-22
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 639186-2
    ISSN 1530-6860 ; 0892-6638
    ISSN (online) 1530-6860
    ISSN 0892-6638
    DOI 10.1096/fj.202000864R
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: Mesenchymal stem cells ameliorate inflammation in an experimental model of Crohn's disease via the mesentery.

    Dave, Maneesh / Dev, Atul / Somoza, Rodrigo A / Zhao, Nan / Viswanath, Satish / Mina, Pooja Rani / Chirra, Prathyush / Obmann, Verena Carola / Mahabeleshwar, Ganapati H / Menghini, Paola / Johnson, Blythe Durbin / Nolta, Jan / Soto, Christopher / Osme, Abdullah / Khuat, Lam T / Murphy, William / Caplan, Arnold I / Cominelli, Fabio

    bioRxiv : the preprint server for biology

    2023  

    Abstract: Objective: Mesenchymal stem cells (MSCs) are novel therapeutics for treatment of Crohn's disease. However, their mechanism of action is unclear, especially in disease-relevant chronic models of inflammation. Thus, we used SAMP-1/YitFc, a chronic and ... ...

    Abstract Objective: Mesenchymal stem cells (MSCs) are novel therapeutics for treatment of Crohn's disease. However, their mechanism of action is unclear, especially in disease-relevant chronic models of inflammation. Thus, we used SAMP-1/YitFc, a chronic and spontaneous murine model of small intestinal inflammation, to study the therapeutic effect and mechanism of human bone marrow-derived MSCs (hMSC).
    Design: hMSC immunosuppressive potential was evaluated through in vitro mixed lymphocyte reaction, ELISA, macrophage co-culture, and RT-qPCR. Therapeutic efficacy and mechanism in SAMP were studied by stereomicroscopy, histopathology, MRI radiomics, flow cytometry, RT-qPCR, small animal imaging, and single-cell RNA sequencing (Sc-RNAseq).
    Results: hMSC dose-dependently inhibited naïve T lymphocyte proliferation in MLR via PGE
    Conclusion: hMSCs result in healing and tissue regeneration in a chronic model of small intestinal inflammation. Despite being short-lived, exert long-term effects via macrophage reprogramming to an anti-inflammatory phenotype.
    Data transparency statement: Single-cell RNA transcriptome datasets are deposited in an online open access repository 'Figshare' (DOI: https://doi.org/10.6084/m9.figshare.21453936.v1 ).
    Language English
    Publishing date 2023-05-24
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2023.05.22.541829
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: CITED2 inhibits STAT1-IRF1 signaling and atherogenesis.

    Zafar, Atif / Pong Ng, Hang / Diamond-Zaluski, Rachel / Kim, Gun-Dong / Ricky Chan, Ernest / Dunwoodie, Sally L / Smith, Jonathan D / Mahabeleshwar, Ganapati H

    FASEB journal : official publication of the Federation of American Societies for Experimental Biology

    2021  Volume 35, Issue 9, Page(s) e21833

    Abstract: Macrophages are the principal component of the innate immune system. They play very crucial and multifaceted roles in the pathogenesis of inflammatory vascular diseases. There is an increasing recognition that transcriptionally dynamic macrophages are ... ...

    Abstract Macrophages are the principal component of the innate immune system. They play very crucial and multifaceted roles in the pathogenesis of inflammatory vascular diseases. There is an increasing recognition that transcriptionally dynamic macrophages are the key players in the pathogenesis of inflammatory vascular diseases. In this context, the accumulation and aberrant activation of macrophages in the subendothelial layers govern atherosclerotic plaque development. Macrophage-mediated inflammation is an explicitly robust biological response that involves broad alterations in inflammatory gene expression. Thus, cell-intrinsic negative regulatory mechanisms must exist which can restrain inflammatory response in a spatiotemporal manner. In this study, we identified CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2) as one such cell-intrinsic negative regulator of inflammation. Our in vivo studies show that myeloid-CITED2-deficient mice on the Apoe
    MeSH term(s) Animals ; Atherosclerosis/genetics ; Female ; Inflammation/genetics ; Interferon Regulatory Factor-1/genetics ; Macrophages/physiology ; Male ; Mice ; Mice, Inbred C57BL ; Promoter Regions, Genetic/genetics ; RAW 264.7 Cells ; Repressor Proteins/genetics ; STAT1 Transcription Factor/genetics ; Signal Transduction/genetics ; Trans-Activators/genetics ; Transcription, Genetic/genetics
    Chemical Substances Cited2 protein, mouse ; Interferon Regulatory Factor-1 ; Irf1 protein, mouse ; Repressor Proteins ; STAT1 Transcription Factor ; Stat1 protein, mouse ; Trans-Activators
    Language English
    Publishing date 2021-07-31
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 639186-2
    ISSN 1530-6860 ; 0892-6638
    ISSN (online) 1530-6860
    ISSN 0892-6638
    DOI 10.1096/fj.202100792R
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: The nucleolus as a polarized coaxial cable in which the rDNA axis is surrounded by dynamic subunit-specific phases.

    Tartakoff, Alan M / Chen, Lan / Raghavachari, Shashank / Gitiforooz, Daria / Dhinakaran, Akshyasri / Ni, Chun-Lun / Pasadyn, Cassandra / Mahabeleshwar, Ganapati H / Pasadyn, Vanessa / Woolford, John L

    Current biology : CB

    2021  Volume 31, Issue 12, Page(s) 2507–2519.e4

    Abstract: In ribosomal DNA (rDNA) repeats, sequences encoding small-subunit (SSU) rRNA precede those encoding large-subunit (LSU) rRNAs. Processing the composite transcript and subunit assembly requires >100 subunit-specific nucleolar assembly factors (AFs). To ... ...

    Abstract In ribosomal DNA (rDNA) repeats, sequences encoding small-subunit (SSU) rRNA precede those encoding large-subunit (LSU) rRNAs. Processing the composite transcript and subunit assembly requires >100 subunit-specific nucleolar assembly factors (AFs). To investigate the functional organization of the nucleolus, we localized AFs in S. cerevisiae in which the rDNA axis was "linearized" to reduce its dimensionality, thereby revealing its coaxial organization. In this situation, rRNA synthesis and processing continue. The axis is embedded in an inner layer/phase of SSU AFs that is surrounded by an outer layer/phase of LSU AFs. When subunit production is inhibited, subsets of AFs differentially relocate between the inner and outer layers, as expected if there is a cycle of repeated relocation whereby "latent" AFs become "operative" when recruited to nascent subunits. Recognition of AF cycling and localization of segments of rRNA make it possible to infer the existence of assembly intermediates that span between the inner and outer layers and to chart the cotranscriptional assembly of each subunit. AF cycling also can explain how having more than one protein phase in the nucleolus makes possible "vectorial 2-phase partitioning" as a driving force for relocation of nascent rRNPs. Because nucleoplasmic AFs are also present in the outer layer, we propose that critical surface remodeling occurs at this site, thereby partitioning subunit precursors into the nucleoplasm for post-transcriptional maturation. Comparison to observations on higher eukaryotes shows that the coaxial paradigm is likely to be applicable for the many other organisms that have rDNA repeats.
    MeSH term(s) Cell Nucleolus/genetics ; DNA, Ribosomal/genetics ; RNA, Ribosomal/genetics ; Saccharomyces cerevisiae/cytology ; Saccharomyces cerevisiae/genetics
    Chemical Substances DNA, Ribosomal ; RNA, Ribosomal
    Language English
    Publishing date 2021-04-15
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2021.03.041
    Database MEDical Literature Analysis and Retrieval System OnLINE

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