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Bersin TV, Cordova KL, Journey ML, Beckman BR, Lema SC. Food deprivation reduces sensitivity of liver Igf1 synthesis pathways to growth hormone in juvenile gopher rockfish (Sebastes carnatus). Gen Comp Endocrinol 2024; 346:114404. [PMID: 37940008 DOI: 10.1016/j.ygcen.2023.114404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/19/2023] [Accepted: 11/03/2023] [Indexed: 11/10/2023]
Abstract
Growth hormone (Gh) regulates growth in part by stimulating the liver to synthesize and release insulin-like growth factor-1 (Igf1), which then promotes somatic growth. However, for fish experiencing food limitation, elevated blood Gh can occur even with low circulating Igf1 and slow growth, suggesting that nutritional stress can alter the sensitivity of liver Igf1 synthesis pathways to Gh. Here, we examined how recent feeding experience affected Gh regulation of liver Igf1 synthesis pathways in juvenile gopher rockfish (Sebastes carnatus) to illuminate mechanisms underlying the nutritional modulation of Igf1 production. Juvenile gopher rockfish were maintained under conditions of feeding or complete food deprivation (fasting) for 14 d and then treated with recombinant sea bream (Sparus aurata) Gh or saline control. Gh upregulated hepatic igf1 mRNA levels in fed fish but not in fasted fish. The liver of fasted rockfish also showed a lower relative abundance of gene transcripts encoding teleost Gh receptors 1 (ghr1) and 2 (ghr2), as well as reduced protein levels of phosphorylated janus tyrosine kinase 2 (pJak2) and signal transducer and activator of transcription 5 (pStat5), which function to induce igf1 gene transcription following Gh binding to Gh receptors. Relative hepatic mRNA levels for suppressors of cytokine signaling (Socs) genes socs2, socs3a, and socs3b were also lower in fasted rockfish. Socs2 can suppress Gh activation of Jak2/Stat5, and fasting-related variation in socs expression may reflect modulated inhibitory control of igf1 gene transcription. Fasted rockfish also had elevated liver mRNA abundances for lipolytic hormone-sensitive lipase 1 (hsl1) and Igf binding proteins igfbp1a, -1b and -3a, reduced liver mRNAs encoding igfbp2b and an Igfbp acid labile subunit-like (igfals) gene, and higher transcript abundances for Igf1 receptors igf1ra and igf1rb in skeletal muscle. Together, these findings suggest that food deprivation impacts liver Igf1 responsiveness to Gh via multiple mechanisms that include a downregulation of hepatic Gh receptors, modulation of the intracellular Jak2/Stat5 transduction pathway, and possible shifts in Socs-inhibitory control of igf1 gene transcription, while also demonstrating that these changes occur in concert with shifts in liver Igfbp expression and muscle Gh/Igf1 signaling pathway components.
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Affiliation(s)
- Theresa V Bersin
- Biological Sciences Department, Center for Coastal Marine Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Kasey L Cordova
- Biological Sciences Department, Center for Coastal Marine Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA
| | - Meredith L Journey
- Lynker Technology, 202 Church St SE #536, Leesburg, VA 20175, USA; Under Contract to Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA
| | - Brian R Beckman
- Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, WA 98112, USA
| | - Sean C Lema
- Biological Sciences Department, Center for Coastal Marine Sciences, California Polytechnic State University, San Luis Obispo, CA 93407, USA.
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2
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Faida P, Attiogbe MKI, Majeed U, Zhao J, Qu L, Fan D. Lung cancer treatment potential and limits associated with the STAT family of transcription factors. Cell Signal 2023:110797. [PMID: 37423343 DOI: 10.1016/j.cellsig.2023.110797] [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: 04/06/2023] [Revised: 06/19/2023] [Accepted: 07/04/2023] [Indexed: 07/11/2023]
Abstract
Lung cancer is one of the mortal cancers and the leading cause of cancer-related mortality, with a cancer survival rate of fewer than 5% in developing nations. This low survival rate can be linked to things like late-stage detection, quick postoperative recurrences in patients receiving therapy, and chemoresistance developing against various lung cancer treatments. Signal transducer and activator of transcription (STAT) family of transcription factors are involved in lung cancer cell proliferation, metastasis, immunological control, and treatment resistance. By interacting with specific DNA sequences, STAT proteins trigger the production of particular genes, which in turn result in adaptive and incredibly specific biological responses. In the human genome, seven STAT proteins have been discovered (STAT1 to STAT6, including STAT5a and STAT5b). Many external signaling proteins can activate unphosphorylated STATs (uSTATs), which are found inactively in the cytoplasm. When STAT proteins are activated, they can increase the transcription of several target genes, which leads to unchecked cellular proliferation, anti-apoptotic reactions, and angiogenesis. The effects of STAT transcription factors on lung cancer are variable; some are either pro- or anti-tumorigenic, while others maintain dual, context-dependent activities. Here, we give a succinct summary of the various functions that each member of the STAT family plays in lung cancer and go into more detail about the advantages and disadvantages of pharmacologically targeting STAT proteins and their upstream activators in the context of lung cancer treatment.
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Affiliation(s)
- Paison Faida
- Shaanxi Key Laboratory of Degradable Biomedical Materials and Shaanxi R&D Center of Biomaterials and Fermentation Engineering, School of Chemical Engineering, Northwest University, Taibai North Road 229, Xi'an, Shaanxi 710069, China; Biotech. & Biomed. Research Institute, Northwest University, Taibai North Road 229, Xi'an, Shaanxi 710069, China
| | - Mawusse K I Attiogbe
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China
| | - Usman Majeed
- College of Food Science and Technology, Northwest University, Xi'an, Shaanxi 710069, China
| | - Jing Zhao
- Shaanxi Key Laboratory of Degradable Biomedical Materials and Shaanxi R&D Center of Biomaterials and Fermentation Engineering, School of Chemical Engineering, Northwest University, Taibai North Road 229, Xi'an, Shaanxi 710069, China; Biotech. & Biomed. Research Institute, Northwest University, Taibai North Road 229, Xi'an, Shaanxi 710069, China
| | - Linlin Qu
- Shaanxi Key Laboratory of Degradable Biomedical Materials and Shaanxi R&D Center of Biomaterials and Fermentation Engineering, School of Chemical Engineering, Northwest University, Taibai North Road 229, Xi'an, Shaanxi 710069, China; Biotech. & Biomed. Research Institute, Northwest University, Taibai North Road 229, Xi'an, Shaanxi 710069, China
| | - Daidi Fan
- Shaanxi Key Laboratory of Degradable Biomedical Materials and Shaanxi R&D Center of Biomaterials and Fermentation Engineering, School of Chemical Engineering, Northwest University, Taibai North Road 229, Xi'an, Shaanxi 710069, China; Biotech. & Biomed. Research Institute, Northwest University, Taibai North Road 229, Xi'an, Shaanxi 710069, China.
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Kahan SM, Bakshi RK, Ingram JT, Hendrickson RC, Lefkowitz EJ, Crossman DK, Harrington LE, Weaver CT, Zajac AJ. Intrinsic IL-2 production by effector CD8 T cells affects IL-2 signaling and promotes fate decisions, stemness, and protection. Sci Immunol 2022; 7:eabl6322. [PMID: 35148200 PMCID: PMC8923238 DOI: 10.1126/sciimmunol.abl6322] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Here, we show that the capacity to manufacture IL-2 identifies constituents of the expanded CD8 T cell effector pool that display stem-like features, preferentially survive, rapidly attain memory traits, resist exhaustion, and control chronic viral challenges. The cell-intrinsic synthesis of IL-2 by CD8 T cells attenuates the ability to receive IL-2-dependent STAT5 signals, thereby limiting terminal effector formation, endowing the IL-2-producing effector subset with superior protective powers. In contrast, the non-IL-2-producing effector cells respond to IL-2 signals and gain effector traits at the expense of memory formation. Despite having distinct properties during the effector phase, IL-2-producing and nonproducing CD8 T cells appear to converge transcriptionally as memory matures to form populations with equal recall abilities. Therefore, the potential to produce IL-2 during the effector, but not memory stage, is a consequential feature that dictates the protective capabilities of the response.
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Affiliation(s)
- Shannon M. Kahan
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States,Present address: NextCure, Beltsville, MD 20705, United States,These authors contributed equally
| | - Rakesh K. Bakshi
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States,Present address: NextCure, Beltsville, MD 20705, United States,Deceased
| | - Jennifer T. Ingram
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - R. Curtis Hendrickson
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Elliot J. Lefkowitz
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - David K. Crossman
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Laurie E. Harrington
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Casey T. Weaver
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Allan J. Zajac
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States,Corresponding Author: Allan J. Zajac
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4
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Cytokines and Transgenic Matrix in Autoimmune Diseases: Similarities and Differences. Biomedicines 2020; 8:biomedicines8120559. [PMID: 33271810 PMCID: PMC7761121 DOI: 10.3390/biomedicines8120559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/16/2020] [Accepted: 11/26/2020] [Indexed: 12/14/2022] Open
Abstract
Autoimmune diseases are increasingly recognized as disease entities in which dysregulated cytokines contribute to tissue-specific inflammation. In organ-specific and multiorgan autoimmune diseases, the cytokine profiles show some similarities. Despite these similarities, the cytokines have different roles in the pathogenesis of different diseases. Altered levels or action of cytokines can result from changes in cell signaling. This article describes alterations in the JAK-STAT, TGF-β and NF-κB signaling pathways, which are involved in the pathogenesis of multiple sclerosis and systemic lupus erythematosus. There is a special focus on T cells in preclinical models and in patients afflicted with these chronic inflammatory diseases.
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5
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Manipulation of JAK/STAT Signalling by High-Risk HPVs: Potential Therapeutic Targets for HPV-Associated Malignancies. Viruses 2020; 12:v12090977. [PMID: 32899142 PMCID: PMC7552066 DOI: 10.3390/v12090977] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/28/2020] [Accepted: 08/30/2020] [Indexed: 12/14/2022] Open
Abstract
Human papillomaviruses (HPVs) are small, DNA viruses that cause around 5% of all cancers in humans, including almost all cervical cancer cases and a significant proportion of anogenital and oral cancers. The HPV oncoproteins E5, E6 and E7 manipulate cellular signalling pathways to evade the immune response and promote virus persistence. The Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway has emerged as a key mediator in a wide range of important biological signalling pathways, including cell proliferation, cell survival and the immune response. While STAT1 and STAT2 primarily drive immune signalling initiated by interferons, STAT3 and STAT5 have widely been linked to the survival and proliferative potential of a number of cancers. As such, the inhibition of STAT3 and STAT5 may offer a therapeutic benefit in HPV-associated cancers. In this review, we will discuss how HPV manipulates JAK/STAT signalling to evade the immune system and promote cell proliferation, enabling viral persistence and driving cancer development. We also discuss approaches to inhibit the JAK/STAT pathway and how these could potentially be used in the treatment of HPV-associated disease.
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6
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Ernst S, Müller-Newen G. Nucleocytoplasmic Shuttling of STATs. A Target for Intervention? Cancers (Basel) 2019; 11:cancers11111815. [PMID: 31752278 PMCID: PMC6895884 DOI: 10.3390/cancers11111815] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/08/2019] [Accepted: 11/13/2019] [Indexed: 12/12/2022] Open
Abstract
Signal transducer and activator of transcription (STAT) proteins are transcription factors that in the latent state are located predominantly in the cytoplasm. Activation of STATs through phosphorylation of a single tyrosine residue results in nuclear translocation. The requirement of tyrosine phosphorylation for nuclear accumulation is shared by all STAT family members but mechanisms of nuclear translocation vary between different STATs. These differences offer opportunities for specific intervention. To achieve this, the molecular mechanisms of nucleocytoplasmic shuttling of STATs need to be understood in more detail. In this review we will give an overview on the various aspects of nucleocytoplasmic shuttling of latent and activated STATs with a special focus on STAT3 and STAT5. Potential targets for cancer treatment will be identified and discussed.
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Affiliation(s)
- Sabrina Ernst
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, 52074 Aachen, Germany;
- Confocal Microscopy Facility, Interdisciplinary Center for Clinical Research IZKF, RWTH Aachen University, 52074 Aachen, Germany
| | - Gerhard Müller-Newen
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, 52074 Aachen, Germany;
- Correspondence:
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7
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Polak KL, Chernosky NM, Smigiel JM, Tamagno I, Jackson MW. Balancing STAT Activity as a Therapeutic Strategy. Cancers (Basel) 2019; 11:cancers11111716. [PMID: 31684144 PMCID: PMC6895889 DOI: 10.3390/cancers11111716] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 10/23/2019] [Accepted: 10/31/2019] [Indexed: 12/13/2022] Open
Abstract
Driven by dysregulated IL-6 family member cytokine signaling in the tumor microenvironment (TME), aberrant signal transducer and activator of transcription (STAT3) and (STAT5) activation have been identified as key contributors to tumorigenesis. Following transformation, persistent STAT3 activation drives the emergence of mesenchymal/cancer-stem cell (CSC) properties, important determinants of metastatic potential and therapy failure. Moreover, STAT3 signaling within tumor-associated macrophages and neutrophils drives secretion of factors that facilitate metastasis and suppress immune cell function. Persistent STAT5 activation is responsible for cancer cell maintenance through suppression of apoptosis and tumor suppressor signaling. Furthermore, STAT5-mediated CD4+/CD25+ regulatory T cells (Tregs) have been implicated in suppression of immunosurveillance. We discuss these roles for STAT3 and STAT5, and weigh the attractiveness of different modes of targeting each cancer therapy. Moreover, we discuss how anti-tumorigenic STATs, including STAT1 and STAT2, may be leveraged to suppress the pro-tumorigenic functions of STAT3/STAT5 signaling.
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Affiliation(s)
- Kelsey L Polak
- Department of Pathology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
| | - Noah M Chernosky
- Department of Pathology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
| | - Jacob M Smigiel
- Department of Pathology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
| | - Ilaria Tamagno
- Department of Pathology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
| | - Mark W Jackson
- Department of Pathology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
- Case Comprehensive Cancer Center, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA.
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8
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Lee KM, Park KH, Hwang JS, Lee M, Yoon DS, Ryu HA, Jung HS, Park KW, Kim J, Park SW, Kim SH, Chun YM, Choi WJ, Lee JW. Inhibition of STAT5A promotes osteogenesis by DLX5 regulation. Cell Death Dis 2018; 9:1136. [PMID: 30429452 PMCID: PMC6235898 DOI: 10.1038/s41419-018-1184-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/19/2018] [Accepted: 10/24/2018] [Indexed: 12/13/2022]
Abstract
The regulation of osteogenesis is important for bone formation and fracture healing. Despite advances in understanding the molecular mechanisms of osteogenesis, crucial modulators in this process are not well-characterized. Here we demonstrate that suppression of signal transducer and activator of transcription 5A (STAT5A) activates distal-less homeobox 5 (DLX5) in human bone marrow-derived stromal cells (hBMSCs) and enhances osteogenesis in vitro and in vivo. We show that STAT5A negatively regulates expression of Dlx5 in vitro and that STAT5A deletion results in increased trabecular and cortical bone mass and bone mineral density in mice. Additionally, STAT5A deletion prevents age-related bone loss. In a murine fracture model, STAT5A deletion was found to significantly enhance bone remodeling by stimulating the formation of a fracture callus. Our findings indicate that STAT5A inhibition enhances bone formation by promoting osteogenesis of BMSCs.
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Affiliation(s)
- Kyoung-Mi Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea.,Severance Biomedical Science Institute, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Kwang Hwan Park
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Ji Suk Hwang
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Moses Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Dong Suk Yoon
- Department of Internal Medicine, Brody School of Medicine at East Carolina University, Greenville, NC, 27834, USA
| | - Hyun Aae Ryu
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Ho Sun Jung
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Ki Won Park
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Jihyun Kim
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea.,Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Sahng Wook Park
- Department of Biochemistry and Molecular Biology, Institute of Genetic Science, Integrated Genomic Research Center for Metabolic Regulation, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Sung-Hwan Kim
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Yong-Min Chun
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Woo Jin Choi
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea
| | - Jin Woo Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea. .,Severance Biomedical Science Institute, Yonsei University College of Medicine, 50-1 Yonsei -ro, Seodaemun-gu, Seoul, 03722, South Korea. .,Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, South Korea.
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9
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Bousoik E, Montazeri Aliabadi H. "Do We Know Jack" About JAK? A Closer Look at JAK/STAT Signaling Pathway. Front Oncol 2018; 8:287. [PMID: 30109213 PMCID: PMC6079274 DOI: 10.3389/fonc.2018.00287] [Citation(s) in RCA: 237] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 07/09/2018] [Indexed: 12/14/2022] Open
Abstract
Janus tyrosine kinase (JAK) family of proteins have been identified as crucial proteins in signal transduction initiated by a wide range of membrane receptors. Among the proteins in this family JAK2 has been associated with important downstream proteins, including signal transducers and activators of transcription (STATs), which in turn regulate the expression of a variety of proteins involved in induction or prevention of apoptosis. Therefore, the JAK/STAT signaling axis plays a major role in the proliferation and survival of different cancer cells, and may even be involved in resistance mechanisms against molecularly targeted drugs. Despite extensive research focused on the protein structure and mechanisms of activation of JAKs, and signal transduction through these proteins, their importance in cancer initiation and progression seem to be underestimated. This manuscript is an attempt to highlight the role of JAK proteins in cancer biology, the most recent developments in targeting JAKs, and the central role they play in intracellular cross-talks with other signaling cascades.
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Affiliation(s)
- Emira Bousoik
- Department of Biomedical and Pharmaceutical Sciences, Center for Targeted Drug Delivery, School of Pharmacy, Chapman University, Irvine, CA, United States.,School of Pharmacy, Omar Al-Mukhtar University, Dèrna, Libya
| | - Hamidreza Montazeri Aliabadi
- Department of Biomedical and Pharmaceutical Sciences, Center for Targeted Drug Delivery, School of Pharmacy, Chapman University, Irvine, CA, United States
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10
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Ocaranza P, Lammoglia JJ, Iñiguez G, Román R, Cassorla F. Effects of thyroid hormone on the GH signal transduction pathway. Growth Horm IGF Res 2014; 24:42-46. [PMID: 24439614 DOI: 10.1016/j.ghir.2014.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 10/30/2013] [Accepted: 01/06/2014] [Indexed: 11/22/2022]
Abstract
BACKGROUND/AIM The importance of thyroid hormone on growth and development in children is well recognized. In addition, linear growth is highly dependent on the response of peripheral tissues to growth hormone, a process known as GH sensitivity, but little is known about the possible effects of T4 on this process. METHODS We determined the effect of stimulation with recombinant human GH (rhGH; 200 ng/mL) alone or in combination with two different concentrations of T4 (250 nM and 500 nM for 24 h) on JAK2 and STAT5 activation in skin fibroblast cultures obtained from prepubertal boys with normal height. RESULTS JAK2 and STAT5 were activated under co-incubation with T4 (at both concentrations) and rhGH in the non-nuclear fraction of the fibroblasts. In addition, after 24h of co-incubation with rhGH and T4 (500 nM), we observed an increase in phospho-STAT5 in the nuclear fraction, when compared to GH and T4 stimulation alone. This effect was not observed when the fibroblasts were co-incubated with GH and the lower concentration of T4 (250 nM). CONCLUSION Combined stimulation with GH and T4 at a concentration of 500 nM increases synergistically nuclear phospho-STAT5 in skin fibroblasts, which may amplify tissue sensitivity to GH. These findings may help to explain the effect of T4 administration on growth velocity in some children with idiopathic short stature.
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Affiliation(s)
- Paula Ocaranza
- Institute of Maternal and Child Research, School of Medicine, University of Chile, Santiago, Chile.
| | - Juan Javier Lammoglia
- Institute of Maternal and Child Research, School of Medicine, University of Chile, Santiago, Chile
| | - Germán Iñiguez
- Institute of Maternal and Child Research, School of Medicine, University of Chile, Santiago, Chile
| | - Rossana Román
- Institute of Maternal and Child Research, School of Medicine, University of Chile, Santiago, Chile
| | - Fernando Cassorla
- Institute of Maternal and Child Research, School of Medicine, University of Chile, Santiago, Chile
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11
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Reich NC. STATs get their move on. JAKSTAT 2013; 2:e27080. [PMID: 24470978 PMCID: PMC3891633 DOI: 10.4161/jkst.27080] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/01/2013] [Accepted: 11/04/2013] [Indexed: 12/18/2022] Open
Abstract
Understanding the mechanisms that regulate dynamic localization of a protein within a cell can provide critical insight to its functional molecular interactions. Signal transducers and activators of transcription (STATs) play essential roles in development, proliferation, and immune defense. However the consequences of STAT hyperactivity can predispose to diseases including autoimmunity and cancer. To function as transcription factors STATs must gain access to the nucleus, and knowledge of the mechanisms that regulate STAT nuclear trafficking can provide a means to control STAT action. This review presents a synopsis of some of the studies that address the nuclear dynamics of the STAT proteins. Evidence suggests that not all STATs are the same. Nuclear import of STAT1 and STAT4 appears linked to their tyrosine phosphorylation and the formation of parallel dimers via reciprocal phosphotyrosine and Src homology 2 domain interactions. This dimer arrangement generates a conformational nuclear localization signal. STAT2 is imported continually to the nucleus in an unphosphorylated state due to its association with IRF9, but the dominant nuclear export signal of STAT2 shuttles the complex back to the cytoplasm. Following STAT2 tyrosine phosphorylation, it can form dimers with STAT1 to affect nuclear import as the trimeric complex (ISGF3). Distinctly, STAT3, STAT5, and STAT6 are continually imported to the nucleus independent of tyrosine phosphorylation. Mutational studies indicate the nuclear localization signals in these STATs require the conformational structure of their coiled-coil domains. Increases in STAT nuclear accumulation following cytokine stimulation appear coordinate with their ability to bind DNA.
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Affiliation(s)
- Nancy C Reich
- Department of Molecular Genetics and Microbiology; Stony Brook University; Stony Brook, NY USA
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12
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Shin HY, Reich NC. Dynamic trafficking of STAT5 depends on an unconventional nuclear localization signal. J Cell Sci 2013; 126:3333-43. [PMID: 23704351 DOI: 10.1242/jcs.123042] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Signal transducer and activator of transcription 5 (STAT5) is crucial for physiological processes that include hematopoiesis, liver metabolism and mammary gland development. However, aberrant continual activity of STAT5 has been causally linked to human leukemias and solid tumor formation. As a regulated transcription factor, precise cellular localization of STAT5 is essential. Conventional nuclear localization signals consist of short stretches of basic amino acids. In this study, we provide evidence that STAT5 nuclear import is dependent on an unconventional nuclear localization signal that functions within the conformation of an extensive coiled-coil domain. Both in vitro binding and in vivo functional assays reveal that STAT5 nuclear import is mediated by the importin-α3/β1 system independently of STAT5 activation by tyrosine phosphorylation. The integrity of the coiled-coil domain is essential for STAT5 transcriptional induction of the β-casein gene following prolactin stimulation as well as its ability to synergize with the glucocorticoid receptor. The glucocorticoid receptor accumulates in the nucleus in response to prolactin and this nuclear import is dependent on STAT5 nuclear import. STAT5 continually shuttles in and out of the nucleus and live cell imaging demonstrates that STAT5 nuclear export is mediated by both chromosome region maintenance 1 (Crm1)-dependent and Crm1-independent pathways. A Crm1-dependent nuclear export signal was identified within the STAT5 N-terminus. These findings provide insight into the fundamental mechanisms that regulate STAT5 nuclear trafficking and cooperation with the glucocorticoid receptor and provide a basis for clinical intervention of STAT5 function in disease.
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Affiliation(s)
- Ha Youn Shin
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794, USA
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13
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Martinez CS, Piazza VG, Ratner LD, Matos MN, González L, Rulli SB, Miquet JG, Sotelo AI. Growth hormone STAT5-mediated signaling and its modulation in mice liver during the growth period. Growth Horm IGF Res 2013; 23:19-28. [PMID: 23245546 DOI: 10.1016/j.ghir.2012.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 11/15/2012] [Accepted: 11/19/2012] [Indexed: 12/31/2022]
Abstract
Postnatal growth exhibits two instances of rapid growth in mice: the first is perinatal and independent of growth hormone (GH), the second is peripuberal and GH-dependent. Signal transducer and activator of transcription 5b (STAT5b) is the main GH-signaling mediator and it is related to IGF1 synthesis and somatic growth. The aim of this work was to assess differential STAT5 sensitivity to GH during the growth period in mouse liver of both sexes. Three representative ages were selected: 1-week-old animals, in the GH-independent phase of growth; 2.5-week-old mice, at the onset of the GH-dependent phase of growth; and 9-week-old young adults. GH-signaling mediators were assessed by immunoblotting, quantitative RT-PCR and immunohistochemistry. GH-induced STAT5 phosphorylation is low at one-week and maximal at 2.5-weeks of age when compared to young adults, accompanied by higher protein content at the onset of growth. Suppressor CIS and phosphatase PTP1B exhibit high levels in one-week animals, which gradually decline, while SOCS2 and SOCS3 display higher levels at adulthood. Nuclear phosphorylated STAT5 is low in one-week animals while in 2.5-week animals it is similar to 9-week control; expression of SOCS3, an early response GH-target gene, mimics this pattern. STAT5 coactivators glucocorticoid receptor (GR) and hepatic nuclear factor 1 (HNF1) abundance is higher in adulthood. Therefore, GH-induced STAT5 signaling presents age-dependent activity in liver, with its maximum coinciding with the onset of GH-dependent phase of growth, accompanied by an age-dependent variation of modulating factors. This work contributes to elucidate the molecular mechanisms implicated in GH responsiveness during growth.
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Affiliation(s)
- Carolina S Martinez
- Instituto de Química y Fisicoquímica Biológicas (UBA-CONICET), Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Junín 956, 1113, Buenos Aires, Argentina
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14
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Latha K, Li M, Chumbalkar V, Gururaj A, Hwang Y, Dakeng S, Sawaya R, Aldape K, Cavenee WK, Bogler O, Furnari FB. Nuclear EGFRvIII-STAT5b complex contributes to glioblastoma cell survival by direct activation of the Bcl-XL promoter. Int J Cancer 2013; 132:509-20. [PMID: 22729867 PMCID: PMC3802533 DOI: 10.1002/ijc.27690] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 06/05/2012] [Indexed: 12/13/2022]
Abstract
Aberrant EGFR signaling strongly promotes glioma malignancy and treatment resistance. The most prevalent mutation, ΔEGFR/EGFRvIII, is an in-frame deletion of the extracellular domain, which occurs in more than 25% of glioblastomas and enhances growth and survival of tumor cells. Paradoxically, the signaling of the potent oncogene ΔEGFR is of low intensity, raising the question of whether it exhibits preferential signaling to key downstream targets. We have observed levels of phosphorylation of STAT5 at position Y699 in cells expressing ΔEGFR that are similar or higher than in cells that overexpress EGFR and are acutely stimulated with EGF, prompting us to investigate the role of STAT5 activation in glioblastoma. Here, we show that in human glioblastoma samples, pSTAT5 levels correlated positively with EGFR expression and were associated with reduced survival. Interestingly, the activation of STAT5b downstream of ΔEGFR was dependent on SFKs, while the signal from acutely EGF-stimulated EGFR to STAT5b involved other kinases. Phosphorylated STAT5b and ΔEGFR associated in the nucleus, bound DNA and were found on promoters known to be regulated by STAT5 including that of the Aurora A gene. ΔEGFR cooperated with STAT5b to regulate the Bcl-XL promoter and knockdown of STAT5b suppressed anchorage independent growth, reduced the levels of Bcl-XL and sensitized glioblastoma cells to cisplatin. Together these results delineate a novel association of nuclear ΔEGFR with STAT5b, which promotes oncogenesis and treatment resistance in glioblastoma by direct regulation of anti-apoptotic gene, Bcl-XL.
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Affiliation(s)
- Khatri Latha
- Department of Neurosurgery, University of Texas MD Anderson Cancer Center, TX, USA.
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15
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Koch V, Staab J, Ruppert V, Meyer T. Two glutamic acid residues in the DNA-binding domain are engaged in the release of STAT1 dimers from DNA. BMC Cell Biol 2012; 13:22. [PMID: 22920460 PMCID: PMC3507856 DOI: 10.1186/1471-2121-13-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 08/21/2012] [Indexed: 12/28/2022] Open
Abstract
Background In interferon-γ-stimulated cells, the dimeric transcription factor STAT1 (signal transducer and activator of transcription 1) recognizes semi-palindromic motifs in the promoter regions of cytokine-driven target genes termed GAS (gamma-activated sites). However, the molecular steps that facilitate GAS binding and the subsequent liberation of STAT1 homodimers from these promoter elements are not well understood. Results Using a mutational approach, we identified two critical glutamyl residues within the DNA-binding domain adjacent to the phosphodiester backbone of DNA which efficiently release phospho-STAT1 from DNA. The release of STAT1 dimers from DNA enhances transcriptional activity on both interferon-driven reporter and endogenous target genes. A substitution of either of the two glutamic acid residues broadens the repertoire of putative binding sites on DNA and enhances binding affinity to GAS sites. However, despite elevated levels of tyrosine phosphorylation and a prolonged nuclear accumulation period, the STAT1 DNA-binding mutants show a significantly reduced transcriptional activity upon stimulation of cells with interferon-γ. This reduced transcriptional response may be explained by the deposition of oligomerized STAT1 molecules outside GAS sites. Conclusions Thus, two negatively charged amino acid residues in the DNA-binding domain are engaged in the liberation of STAT1 from DNA, resulting in a high dissociation rate from non-GAS sites as a key feature of STAT1 signal transduction, which positively regulates cytokine-dependent gene expression probably by preventing retention at transcriptionally inert sites.
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Affiliation(s)
- Verena Koch
- Klinik für Kardiologie, Philipps-Universität Marburg, Marburg, Germany
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16
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Beier UH, Wang L, Han R, Akimova T, Liu Y, Hancock WW. Histone deacetylases 6 and 9 and sirtuin-1 control Foxp3+ regulatory T cell function through shared and isoform-specific mechanisms. Sci Signal 2012; 5:ra45. [PMID: 22715468 DOI: 10.1126/scisignal.2002873] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Therapeutic inhibition of the histone deacetylases HDAC6, HDAC9, or sirtuin-1 (Sirt1) augments the suppressive functions of regulatory T cells (T(regs)) that contain the transcription factor Foxp3 (Forkhead box P3) and is useful in organ transplant patients or patients with autoimmune diseases. However, it is unclear whether distinct mechanisms are involved for each HDAC or whether combined inhibition of HDACs would be more effective. We compared the suppressive functions of T(regs) from wild-type C57BL/6 mice with those from mice with either complete or cell-specific deletion of various HDACs, as well as with those of T(regs) treated with isoform-selective HDAC inhibitors. The improvement of T(reg) suppressive function mediated by inhibition of HDAC6, but not Sirt1, required an intact heat shock response. Although HDAC6, HDAC9, and Sirt1 all deacetylated Foxp3, each protein had different effects on transcription factors that control expression of the gene encoding Foxp3. For example, loss of HDAC9, but not other HDACs, was associated with stabilization of the acetylated form of signal transducer and activator of transcription 5 (STAT5) and promoted its transcriptional activity. Thus, targeting different HDACs increased T(reg) function through multiple and additive mechanisms, which suggests the therapeutic potential for using combinations of HDAC inhibitors in the management of autoimmunity and organ transplantation.
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Affiliation(s)
- Ulf H Beier
- Division of Nephrology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
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17
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Abstract
Since its discovery two decades ago, the activation of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway by numerous cytokines and growth factors has resulted in it becoming one of the most well-studied intracellular signalling networks. The field has progressed from the identification of the individual components to high-resolution crystal structures of both JAK and STAT, and an understanding of the complexities of the molecular activation and deactivation cycle which results in a diverse, yet highly specific and regulated pattern of transcriptional responses. While there is still more to learn, we now appreciate how disruption and deregulation of this pathway can result in clinical disease and look forward to adoption of the next generation of JAK inhibitors in routine clinical treatment.
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Affiliation(s)
- Hiu Kiu
- Walter & Eliza Hall Institute, 1G Royal Parade, Parkville 3052, Australia
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18
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Mohr A, Chatain N, Domoszlai T, Rinis N, Sommerauer M, Vogt M, Müller-Newen G. Dynamics and non-canonical aspects of JAK/STAT signalling. Eur J Cell Biol 2011; 91:524-32. [PMID: 22018664 DOI: 10.1016/j.ejcb.2011.09.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 09/05/2011] [Accepted: 09/12/2011] [Indexed: 11/25/2022] Open
Abstract
The Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway directly links ligand-binding to a membrane-bound receptor with the activation of a transcription factor. This signalling module enables the cell to rapidly initiate a transcriptional response to external stimulation. The main components of this evolutionary conserved module are cytokines that specifically bind to cytokine receptors leading to the activation of receptor-associated Janus tyrosine kinases (JAKs). The receptor-bound JAKs activate STAT transcription factors through phosphorylation of a single tyrosine residue. Activated STAT dimers translocate into the nucleus to induce target gene expression. In this article we will review current opinions on the molecular mechanism and on intracellular dynamics of JAK/STAT signalling with a special focus on the cytokine receptor glycoprotein 130 (gp130) and STAT3. In particular we will concentrate on non-canonical aspects of Jak/STAT signalling including preassembled receptor complexes, preformed STAT dimers, STAT trafficking and non-canonical functions of STATs.
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Affiliation(s)
- Anne Mohr
- Institut für Biochemie und Molekularbiologie, RWTH Aachen University, Aachen, Germany
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19
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Beier UH, Akimova T, Liu Y, Wang L, Hancock WW. Histone/protein deacetylases control Foxp3 expression and the heat shock response of T-regulatory cells. Curr Opin Immunol 2011; 23:670-8. [PMID: 21798734 PMCID: PMC3190028 DOI: 10.1016/j.coi.2011.07.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 07/02/2011] [Indexed: 01/03/2023]
Abstract
Lysine ɛ-acetylation is a post-translational modification that alters the biochemical properties of many proteins. The reaction is catalyzed by histone/protein acetyltransferases (HATs), and is reversed by histone/protein deacetylases (HDACs). As a result, HATs and HDACs constitute an important, though little recognized, set of proteins that control the functions of T-regulatory (Treg) cells. Targeting certain HDACs, especially HDAC6, HDAC9, and Sirtuin-1 (Sirt1), can augment Treg suppressive potency by several distinct and potentially additive mechanisms. These involve promoting Forkhead box p3 (Foxp3) gene expression and preserving Foxp3 lysine ɛ-acetylation, which infers resistance to ubiquitination and proteasomal degradation, and increases DNA binding. Moreover, depleting certain HDAC can enhance the heat shock response, which increases the tenacity of Treg to survive under stress, and helps preserve a suppressive phenotype. As a result, HDAC inhibitor therapy can be used to enhance Treg functions in vivo and have beneficial effects on allograft survival and autoimmune diseases.
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Affiliation(s)
- Ulf H. Beier
- Division of Nephrology, Department of Pediatrics, The Children’s Hospital of Philadelphia, and University of Pennsylvania School of Medicine
| | - Tatiana Akimova
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, The Children’s Hospital of Philadelphia, and University of Pennsylvania School of Medicine
| | - Yujie Liu
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, The Children’s Hospital of Philadelphia, and University of Pennsylvania School of Medicine
| | - Liqing Wang
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, The Children’s Hospital of Philadelphia, and University of Pennsylvania School of Medicine
| | - Wayne W. Hancock
- Division of Transplant Immunology, Department of Pathology and Laboratory Medicine, The Children’s Hospital of Philadelphia, and University of Pennsylvania School of Medicine
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20
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Koptyra M, Gupta S, Talati P, Nevalainen MT. Signal transducer and activator of transcription 5a/b: biomarker and therapeutic target in prostate and breast cancer. Int J Biochem Cell Biol 2011; 43:1417-21. [PMID: 21704724 DOI: 10.1016/j.biocel.2011.06.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 06/09/2011] [Accepted: 06/10/2011] [Indexed: 01/23/2023]
Abstract
The search for new therapeutic strategies for prostate and breast cancer is of significant interest. Signal transducer and activator of transcription 5a/b (Stat5a/b) controls viability and growth of prostate cancer. Nuclear active Stat5a/b expression is clustered to high grade prostate cancers, predicts early disease recurrence and promotes metastatic dissemination of prostate cancer. In breast cancer, the role of Stat5a/b is more complex. In rodent model systems, Stat5a/b may promote malignant transformation and enhance growth of the breast tumors. In contrast, Stat5a/b activation in established human breast cancer positively correlates with tumor differentiation, prevents metastatic dissemination, and predicts favorable clinical outcome of node-negative breast cancer. Here we review the molecular structure and biological functions of Stat5a/b and discuss the potential applications of Stat5a/b for therapy development and as a prognostic marker for prostate and breast cancer.
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Affiliation(s)
- Mateusz Koptyra
- Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, United States
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21
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Ferbeyre G, Moriggl R. The role of Stat5 transcription factors as tumor suppressors or oncogenes. Biochim Biophys Acta Rev Cancer 2010; 1815:104-14. [PMID: 20969928 DOI: 10.1016/j.bbcan.2010.10.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 10/08/2010] [Accepted: 10/08/2010] [Indexed: 02/06/2023]
Abstract
Stat5 is constitutively activated in many human cancers affecting the expression of cell proliferation and cell survival controlling genes. These oncogenic functions of Stat5 have been elegantly reproduced in mouse models. Aberrant Stat5 activity induces also mitochondrial dysfunction and reactive oxygen species leading to DNA damage. Although DNA damage can stimulate tumorigenesis, it can also prevent it. Stat5 can inhibit tumor progression like in the liver and it is a tumor suppressor in fibroblasts. Stat5 proteins are able to regulate cell differentiation and senescence activating the tumor suppressors SOCS1, p53 and PML. Understanding the context dependent regulation of tumorigenesis through Stat5 function will be central to understand proliferation, survival, differentiation or senescence of cancer cells.
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Affiliation(s)
- G Ferbeyre
- Département de Biochimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada.
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22
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Pfeifer AC, Kaschek D, Bachmann J, Klingmüller U, Timmer J. Model-based extension of high-throughput to high-content data. BMC SYSTEMS BIOLOGY 2010; 4:106. [PMID: 20687942 PMCID: PMC2928782 DOI: 10.1186/1752-0509-4-106] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 08/05/2010] [Indexed: 12/23/2022]
Abstract
Background High-quality quantitative data is a major limitation in systems biology. The experimental data used in systems biology can be assigned to one of the following categories: assays yielding average data of a cell population, high-content single cell measurements and high-throughput techniques generating single cell data for large cell populations. For modeling purposes, a combination of data from different categories is highly desirable in order to increase the number of observable species and processes and thereby maximize the identifiability of parameters. Results In this article we present a method that combines the power of high-content single cell measurements with the efficiency of high-throughput techniques. A calibration on the basis of identical cell populations measured by both approaches connects the two techniques. We develop a mathematical model to relate quantities exclusively observable by high-content single cell techniques to those measurable with high-content as well as high-throughput methods. The latter are defined as free variables, while the variables measurable with only one technique are described in dependence of those. It is the combination of data calibration and model into a single method that makes it possible to determine quantities only accessible by single cell assays but using high-throughput techniques. As an example, we apply our approach to the nucleocytoplasmic transport of STAT5B in eukaryotic cells. Conclusions The presented procedure can be generally applied to systems that allow for dividing observables into sets of free quantities, which are easily measurable, and variables dependent on those. Hence, it extends the information content of high-throughput methods by incorporating data from high-content measurements.
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Affiliation(s)
- Andrea C Pfeifer
- Division Systems Biology of Signal Transduction, DKFZ-ZMBH Alliance, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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23
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Stat5a serine 725 and 779 phosphorylation is a prerequisite for hematopoietic transformation. Blood 2010; 116:1548-58. [PMID: 20508164 DOI: 10.1182/blood-2009-12-258913] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Stat5 transcription factors are essential gene regulators promoting proliferation, survival, and differentiation of all hematopoietic cell types. Mutations or fusions of oncogenic tyrosine kinases often result in constitutive Stat5 activation. We have modeled persistent Stat5 activity by using an oncogenic Stat5a variant (cS5). To analyze the hitherto unrecognized role of Stat5 serine phosphorylation in this context, we have generated cS5 constructs with mutated C-terminal serines 725 and 779, either alone or in combination. Genetic complementation assays in primary Stat5(null/null) mast cells and Stat5(DeltaN) T cells demonstrated reconstitution of proliferation with these mutants. Similarly, an in vivo reconstitution experiment of transduced Stat5(null/null) fetal liver cells transplanted into irradiated wild-type recipients revealed that these mutants exhibit biologic activity in lineage differentiation. By contrast, the leukemogenic potential of cS5 in bone marrow transplants decreased dramatically in cS5 single-serine mutants or was completely absent upon loss of both serine phosphorylation sites. Our data suggest that Stat5a serine phosphorylation is a prerequisite for cS5-mediated leukemogenesis. Hence, interference with Stat5a serine phosphorylation might provide a new therapeutic option for leukemia and myeloid dysplasias without affecting major functions of Stat5 in normal hematopoiesis.
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24
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Vázquez-Iglesias L, Lostalé-Seijo I, Martínez-Costas J, Benavente J. Avian reovirus sigmaA localizes to the nucleolus and enters the nucleus by a nonclassical energy- and carrier-independent pathway. J Virol 2009; 83:10163-75. [PMID: 19640987 PMCID: PMC2747991 DOI: 10.1128/jvi.01080-09] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 07/16/2009] [Indexed: 12/24/2022] Open
Abstract
Avian reovirus sigmaA is a double-stranded RNA (dsRNA)-binding protein that has been shown to stabilize viral core particles and to protect the virus against the antiviral action of interferon. To continue with the characterization of this viral protein, we have investigated its intracellular distribution in avian cells. Most sigmaA accumulates into cytoplasmic viral factories of infected cells, and yet a significant fraction was detected in the nucleolus. The protein also localizes in the nucleolus of transfected cells, suggesting that nucleolar targeting is not facilitated by the viral infection or by viral factors. Assays performed in both intact cells and digitonin-permeabilized cells demonstrate that sigmaA is able to enter the nucleus via a nucleoporin-dependent nondiffusional mechanism that does not require added cytosolic factors or energy input. These results indicate that sigmaA by itself is able to penetrate into the nucleus using a process that is mechanistically different from the classical nuclear localization signal/importin pathway. On the other hand, two sigmaA arginines that are necessary for dsRNA binding are also required for nucleolar localization, suggesting that dsRNA-binding and nucleolar targeting are intimately linked properties of the viral protein.
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Affiliation(s)
- Lorena Vázquez-Iglesias
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Santiago de Compostela, Santiago de Compostela, Spain
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25
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A Rac GTPase-activating protein, MgcRacGAP, is a nuclear localizing signal-containing nuclear chaperone in the activation of STAT transcription factors. Mol Cell Biol 2009; 29:1796-813. [PMID: 19158271 DOI: 10.1128/mcb.01423-08] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In addition to their pleiotropic functions under physiological conditions, transcription factors STAT3 and STAT5 also have oncogenic activities, but how activated STATs are transported to the nucleus has not been fully understood. Here we show that an MgcRacGAP mutant lacking its nuclear localizing signal (NLS) blocks nuclear translocation of p-STATs both in vitro and in vivo. Unlike wild-type MgcRacGAP, this mutant did not promote complex formation of phosphorylated STATs (p-STATs) with importin alpha in the presence of GTP-bound Rac1, suggesting that MgcRacGAP functions as an NLS-containing nuclear chaperone. We also demonstrate that mutants of STATs lacking the MgcRacGAP binding site (the strand betab) are hardly tyrosine phosphorylated after cytokine stimulation. Intriguingly, mutants harboring small deletions in the C'-adjacent region (betab-betac loop region) of the strand betab became constitutively active with the enhanced binding to MgcRacGAP. The molecular basis of this phenomenon will be discussed, based on the computer-assisted tertiary structure models of STAT3. Thus, MgcRacGAP functions as both a critical mediator of STAT's tyrosine phosphorylation and an NLS-containing nuclear chaperone of p-STATs.
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26
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Tan SH, Nevalainen MT. Signal transducer and activator of transcription 5A/B in prostate and breast cancers. Endocr Relat Cancer 2008; 15:367-90. [PMID: 18508994 PMCID: PMC6036917 DOI: 10.1677/erc-08-0013] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Protein kinase signaling pathways, such as Janus kinase 2-Signal transducer and activator of transcription 5A/B (JAK2-STAT5A/B), are of significant interest in the search for new therapeutic strategies in both breast and prostate cancers. In prostate cancer, the components of the JAK2-STAT5A/B signaling pathway provide molecular targets for small-molecule inhibition of survival and growth signals of the cells. At the same time, new evidence suggests that the STAT5A/B signaling pathway is involved in the transition of organ-confined prostate cancer to hormone-refractory disease. This implies that the active JAK2-STAT5A/B signaling pathway potentially provides the means for pharmacological intervention of clinical prostate cancer progression. In addition, active STAT5A/B may serve as a prognostic marker for identification of those primary prostate cancers that are likely to progress to aggressive disease. In breast cancer, the role of STAT5A/B is more complex. STAT5A/B may have a dual role in the regulation of malignant mammary epithelium. Data accumulated from mouse models of breast cancer suggest that in early stages of breast cancer STAT5A/B may promote malignant transformation and enhance growth of the tumor. This is in contrast to established breast cancer, where STAT5A/B may mediate the critical cues for maintaining the differentiation of mammary epithelium. In addition, present data suggest that activation of STAT5A/B in breast cancer predicts favorable clinical outcome. The dual nature of STAT5A/B action in breast cancer makes the therapeutic use of STAT5 A/B more complex.
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Affiliation(s)
- Shyh-Han Tan
- Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, 233 South 10th Street, BLSB 309, Philadelphia, Pennsylvania 19107, USA
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27
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Basham B, Sathe M, Grein J, McClanahan T, D'Andrea A, Lees E, Rascle A. In vivo identification of novel STAT5 target genes. Nucleic Acids Res 2008; 36:3802-18. [PMID: 18492722 PMCID: PMC2441806 DOI: 10.1093/nar/gkn271] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
STAT5A and STAT5B proteins belong to the family of signal transducers and activators of transcription. They are encoded by two separate genes with 91% identity in their amino acid sequences. Despite their high degree of conservation, STAT5A and STAT5B exert non-redundant functions, resulting at least in part from differences in target gene activation. To better characterize the differential contribution of STAT5A and STAT5B in gene regulation, we performed single or double knockdown of STAT5A and STAT5B using small interfering RNA. Subsequent gene expression profiling and RT-qPCR analyses of IL-3-stimulated Ba/F3-β cells led to the identification of putative novel STAT5 target genes. Chromatin immunoprecipitation assays analyzing the corresponding gene loci identified unusual STAT5 binding sites compared to conventional STAT5 responsive elements. Some of the STAT5 targets identified are upregulated in several human cancers, suggesting that they might represent potential oncogenes in STAT5-associated malignancies.
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Affiliation(s)
- Beth Basham
- Schering-Plough Biopharma, 901 California Avenue, Palo Alto, CA 94304, USA
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28
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Saint Fleur S, Fujii H. Cytokine-induced nuclear translocation of signaling proteins and their analysis using the inducible translocation trap system. Cytokine 2008; 41:187-97. [PMID: 18203617 DOI: 10.1016/j.cyto.2007.11.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 11/06/2007] [Accepted: 11/20/2007] [Indexed: 11/16/2022]
Abstract
Binding of cytokines to their specific receptors induces activation of signal transduction pathways, many of which involve nuclear translocation of signaling proteins. In this review, an overview of cytokine-induced nuclear translocation of signaling proteins is provided. In addition, inducible translocation trap (ITT), a novel reporter-based system to detect nuclear translocation, and its application for identification of nuclear translocating proteins are elaborated. Finally, analysis of "nuclear translocatome", the entire set of proteins that translocate into or out of the nucleus in response to extracellular stimuli, by ITT is discussed.
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Affiliation(s)
- Shella Saint Fleur
- Department of Pathology, New York University School of Medicine, 550 First Avenue, MSB-126, New York, NY 10016, USA
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29
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Abstract
Controlled nucleocytoplasmic localization regulates activity of NF kappa B as well as other transcription factors. Analysis of the nucleocytoplasmic protein shuttling has been greatly facilitated by the use of leptomycin B (LMB), an inhibitor of CRM1-dependent nuclear export. The authors have previously shown that LMB inhibits NF kappa B activity in human neutrophils by increasing the nuclear accumulation of NF kappa B inhibitor, I kappa B alpha. In this chapter, the authors describe a protocol that uses LMB to study the nucleocytoplasmic shuttling of I kappa B alpha in human macrophage-like U937 cells, thus inhibiting NF kappa B activity. This protocol should be readily adaptable to analyze the nucleocytoplasmic shuttling of other proteins in human leukocytes.
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30
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Meyer T, Vinkemeier U. STAT nuclear translocation: potential for pharmacological intervention. Expert Opin Ther Targets 2007; 11:1355-65. [PMID: 17907964 DOI: 10.1517/14728222.11.10.1355] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The signal transducer and activator of transcription (STAT) proteins are extracellular ligand-responsive transcription factors that mediate broadly diverse biological processes, including cell proliferation, transformation, apoptosis, differentiation, fetal development, inflammation and immune response. Stimulation with multiple cytokines or growth factors all result in the tyrosine phosphorylation of STAT proteins and the subsequent gene regulation via their direct binding to the promoters of responsive genes. Cytokine-regulated gene activation is dependent on the continuous nucleocytoplasmic cycling of STAT signal transducers. The STATs use intricately intertwined karyopherin-dependent and -independent translocation mechanisms to coordinate the activation step at the cell membrane and gene expression in the nucleus. In addition, STATs appear to have cytokine-independent gene regulatory functions that may also depend on their regulated nucleocytoplasmic transfer. Numerous studies have implicated aberrant STAT signalling in cancer, immune defects and inflammatory diseases. Given the central role of intracellular trafficking for the proper signal processing by STAT proteins, pharmacological targeting of STAT nucleocytoplasmic translocation appears to be an attractive strategy to interfere with dysregulated cytokine signalling. This review will discuss possible scenarios that would result from the use of novel modulators of STAT shuttling, which may both increase or decrease STAT activation and, hence, transcriptional activity.
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Affiliation(s)
- Thomas Meyer
- Philipps-Universität Marburg, Klinik für Kardiologie und Klinik für Psychosomatische Medizin und Psychotherapie, Baldingerstrasse 1, 35033 Marburg, Germany.
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Herrmann A, Vogt M, Mönnigmann M, Clahsen T, Sommer U, Haan S, Poli V, Heinrich PC, Müller-Newen G. Nucleocytoplasmic shuttling of persistently activated STAT3. J Cell Sci 2007; 120:3249-61. [PMID: 17726064 DOI: 10.1242/jcs.03482] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Persistent activation of the transcription factor STAT3 has been detected in many types of cancer and plays an important role in tumor progression, immune evasion and metastasis. To analyze persistent STAT3 activation we coexpressed STAT3 with v-Src. We found that tyrosine phosphorylation of STAT3 by v-Src is independent of Janus kinases (Jaks), the canonical activators of STATs. The STAT3-induced feedback inhibitor, suppressor of cytokine signaling 3 (SOCS3), did not interfere with STAT3 activation by v-Src. However, the protein inhibitor of activated STAT3 (PIAS3) suppressed gene induction by persistently activated STAT3. We measured nucleocytoplasmic shuttling of STAT3 in single cells by bleaching the YFP moiety of double-labelled STAT3-CFP-YFP in the cytoplasm. Analysis of the subcellular distribution of CFP and YFP fluorescence over time by mathematical modeling and computational parameter estimation revealed that activated STAT3 shuttles more rapidly than non-activated STAT3. Inhibition of exportin-1-mediated nuclear export slowed down nucleocytoplasmic shuttling of v-Src-activated STAT3 resulting in reduced tyrosine phosphorylation, decreased induction of STAT3 target genes and increased apoptosis. We propose passage of persistently activated STAT3 through the nuclear pore complex as a new target for intervention in cancer.
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Affiliation(s)
- Andreas Herrmann
- Institut für Biochemie, Universitätsklinikum RWTH Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany
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Iyer J, Reich NC. Constitutive nuclear import of latent and activated STAT5a by its coiled coil domain. FASEB J 2007; 22:391-400. [PMID: 17846080 DOI: 10.1096/fj.07-8965com] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Signal transducer and activator of transcription 5a (STAT5a) is a critical transcription factor for a number of physiological processes including hematopoiesis and mammary gland development. Cytokines such as growth hormone, prolactin, erythropoietin, and interleukin-2 stimulate the activation of STAT5a by tyrosine phosphorylation. Tyrosine phosphorylation confers a conformational change and the ability to bind specific target DNA. To execute its function as a signaling molecule and transcription factor, accurate cellular localization of STAT5a is essential. This study explores the nuclear trafficking of STAT5a both before phosphorylation and after tyrosine phosphorylation. With the use of live cell imaging we demonstrate the continuous shuttling of STAT5a in and out of the nucleus. Evaluation of a series of mutations and deletions identifies a region within the coiled coil domain of STAT5a that is critical for nuclear import of both unphosphorylated and tyrosine-phosphorylated forms. The mechanism that regulates transport of STAT5a through nuclear pore complexes into the nucleus is therefore independent of tyrosine phosphorylation. However, after tyrosine phosphorylation, STAT5a accumulates in the nucleus because of its retention by DNA binding. These findings should provide a foundation for further studies that involve targeting the activity of STAT5a.
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Affiliation(s)
- Janaki Iyer
- Dept. of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794, USA
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Granillo AR, Boffi JC, Barañao L, Kordon E, Pecci A, Guberman A. STAT5 transcriptional activity is impaired by LIF in a mammary epithelial cell line. Biochem Biophys Res Commun 2007; 356:727-32. [PMID: 17382296 DOI: 10.1016/j.bbrc.2007.03.040] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Accepted: 03/07/2007] [Indexed: 11/29/2022]
Abstract
Gene regulation mediated by STAT factors has been implicated in cellular functions with relevance to a variety of processes. Particularly, STAT5 and STAT3 play a crucial role in mammary epithelium displaying reciprocal activation kinetics during pregnancy, lactation and involution. Here, we show that LIF treatment of mammary epithelial HC11 cells reduces the phosphorylation levels and transcriptional activity of p-STAT5 in correlation with STAT3 phosphorylation. We have also found that STAT5 activity is negatively modulated by this cytokine, both on a gene whose expression is induced, as well as on a promoter repressed by STAT5. Besides, our results show that lactogenic hormones increase LIF effect on gene induction without modifying STAT3 phosphorylation state. Our findings strongly suggest that there is crosstalk between STAT5 and STAT3 pathways that could modulate their ability to regulate gene expression.
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Affiliation(s)
- Agustina Rodriguez Granillo
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pab. II, Piso 2, Ciudad Universitaria, C1428EGA Buenos Aires, Argentina
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Kawashima T, Bao YC, Nomura Y, Moon Y, Tonozuka Y, Minoshima Y, Hatori T, Tsuchiya A, Kiyono M, Nosaka T, Nakajima H, Williams DA, Kitamura T. Rac1 and a GTPase-activating protein, MgcRacGAP, are required for nuclear translocation of STAT transcription factors. ACTA ACUST UNITED AC 2007; 175:937-46. [PMID: 17178910 PMCID: PMC2064703 DOI: 10.1083/jcb.200604073] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
STAT transcription factors are tyrosine phosphorylated upon cytokine stimulation and enter the nucleus to activate target genes. We show that Rac1 and a GTPase-activating protein, MgcRacGAP, bind directly to p-STAT5A and are required to promote its nuclear translocation. Using permeabilized cells, we find that nuclear translocation of purified p-STAT5A is dependent on the addition of GTP-bound Rac1, MgcRacGAP, importin α, and importin β. p-STAT3 also enters the nucleus via this transport machinery, and mutant STATs lacking the MgcRacGAP binding site do not enter the nucleus even after phosphorylation. We conclude that GTP-bound Rac1 and MgcRacGAP function as a nuclear transport chaperone for activated STATs.
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Affiliation(s)
- Toshiyuki Kawashima
- Division of Cellular Therapy, The Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
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Cui X, Zhang L, Luo J, Rajasekaran A, Hazra S, Cacalano N, Dubinett SM. Unphosphorylated STAT6 contributes to constitutive cyclooxygenase-2 expression in human non-small cell lung cancer. Oncogene 2007; 26:4253-60. [PMID: 17237818 DOI: 10.1038/sj.onc.1210222] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cyclooxygenase-2 (COX-2) is frequently overexpressed in human cancers and contributes to the malignant phenotype. Our data indicate unphosphorylated signal transducers and activators of transcription 6 (STAT6) may transcriptionally upregulate COX-2 expression and protect against apoptosis in NSCLC cells. In A427 and H2122, NSCLC cell lines that constitutively express COX-2, only unphosphorylated STAT6 was detectable by western blot, thus, all of the following STAT6-dependent effects are attributed to the unphosphorylated protein. In both cell lines, small-interfering RNA-mediated knockdown of STAT6 or stable expression of dominant-negative STAT6 decreased COX-2 expression. In contrast, transfection with a phosphorylation-deficient mutant STAT6 increased COX-2 levels. Immunofluorescent staining revealed the presence of STAT6 in H2122 nuclei, suggesting a direct role in gene regulation for the unphosphorylated protein. Consistent with this hypothesis, unphosphorylated STAT6 increased luciferase expression from a COX-2 promoter reporter construct. STAT6 co-immunoprecipitated with the transcriptional co-activator, p300, and chromatin immunoprecipitation assays demonstrated that these proteins bind a consensus STAT6 binding site located within the COX-2 promoter. STAT6 DNA-binding specificity was confirmed by electrophoretic mobility shift assay. As COX-2 over-expression has been clearly linked to apoptosis resistance and other hallmarks of malignancy, these findings suggest a novel role of unphosphorylated STAT6 in the pathogenesis of non-small cell lung cancer.
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Affiliation(s)
- X Cui
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Lung Cancer Research Program of the Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA
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Lim CP, Cao X. Structure, function, and regulation of STAT proteins. MOLECULAR BIOSYSTEMS 2006; 2:536-50. [PMID: 17216035 DOI: 10.1039/b606246f] [Citation(s) in RCA: 235] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Signal Transducer and Activator of Transcription (STAT) family of proteins was first discovered in the 1990's as key proteins in cytokine signaling. Since then, the field has greatly advanced in the past 15 years, providing significant insight into the structure, function, and regulation of STATs. STATs are latent cytoplasmic transcription factors consisting of seven mammalian members. They are Tyr phosphorylated upon activation, a post-translational modification critical for dimerization, nuclear import, DNA binding, and transcriptional activation. In recent years, unphosphorylated STATs have also been observed to dimerize and drive transcription, albeit by yet an obscure mechanism. In addition, the function of cytoplasmic STATs is beginning to emerge. Here, we describe the structure, function, and regulation of both unphosphorylated and phosphorylated STATs. STAT isoforms from alternative splicing or proteolytic processing, and post-translational modifications affecting STAT activities are also discussed.
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Affiliation(s)
- Cheh Peng Lim
- Signal Transduction Laboratory, Institute of Molecular and Cell Biology, Singapore, 138673, Republic of Singapore
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Biener-Ramanujan E, Ramanujan VK, Herman B, Gertler A. Spatio-temporal kinetics of growth hormone receptor signaling in single cells using FRET microscopy. Growth Horm IGF Res 2006; 16:247-257. [PMID: 16950496 DOI: 10.1016/j.ghir.2006.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Revised: 06/13/2006] [Accepted: 06/14/2006] [Indexed: 10/24/2022]
Abstract
The growth hormone (GH) receptor (R)-mediated JAK2 (Janus kinase-2)-STAT5 (signaling transducer and activator of transcription-5) pathway involves a cascade of protein-protein interactions and tyrosine phosphorylations that occur in a spatially and temporally sensitive manner in cells. To study GHR dimerization or GH-induced conformational change of predimerized GHRs and STAT5 activation kinetics in intact cells, fluorescence resonance energy transfer (FRET) and live-cell imaging methods were employed. FRET measurements at the membrane of HEK-293T cells co-expressing GHRs tagged at the C-terminus with cyan (C) and yellow (Y) fluorescent proteins (FPs) revealed transient GHR dimerization lasting 2-3 min, with a maximum at 3 min after GH stimulation, which was sufficient to induce STAT5 activation. The transient nature of the dimerization or GH-induced conformational change of predimerized GHRs kinetics was not a result of GHR internalization, as neither potassium- nor cholesterol-depletion treatments prolonged the FRET signal. YFP-tagged STAT5 recruitment to the membrane, binding to GHR-CFP, and phosphorylation, occurred within minutes of GH stimulation. Activated STAT5a-YFP did not show nuclear accumulation, despite nuclear pSTAT5 increase, suggesting high turnover of STAT5 nuclear shuttling. Although GHR dimerization and STAT5 activation have been reported previously, this is the first spatially resolved demonstration of GHR-signaling kinetics in intact cells.
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Affiliation(s)
- Eva Biener-Ramanujan
- The Institute of Biochemistry, Food Science, and Nutrition, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot, Israel
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Abstract
Accurate cellular localization is crucial for the effective function of most signalling molecules and nuclear translocation is central to the function of transcription factors. The passage of large molecules between the cytoplasm and nucleus is restricted, and this restriction affords a mechanism to regulate transcription by controlling the access of transcription factors to the nucleus. In this Review, we focus on the signal transducer and activator of transcription (STAT) family of transcription factors. The regulation of the nuclear trafficking of STAT-family members is diverse. Some STAT proteins constitutively shuttle between the nucleus and cytoplasm, whereas others require tyrosine phosphorylation for nuclear localization. In either case, the regulation of nuclear trafficking can provide a target for therapeutic intervention.
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Affiliation(s)
- Nancy C Reich
- Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11777, USA.
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Chen Y, Dai X, Haas AL, Wen R, Wang D. Proteasome-dependent down-regulation of activated Stat5A in the nucleus. Blood 2006; 108:566-74. [PMID: 16569768 PMCID: PMC1895487 DOI: 10.1182/blood-2005-12-4777] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
A broad spectrum of cytokines can activate the signal transducer and activator of transcription 5 (Stat5) by inducing a single tyrosine phosphorylation of the molecule. Although the process of Stat5 activation has been well studied, the mechanism by which it is inactivated is not fully understood. We demonstrate that the proteasome inhibitor MG132, but not the nuclear export inhibitor leptomycin B (LMB), stabilizes active nuclear Stat5A, whereas MG132 only partially stabilizes active cytoplasmic Stat5A. Importantly, ubiquitinated Stat5A is detected in the nucleus and the polyubiquitination of active Stat5A is K48 linked, a linkage type targeting proteins for degradation. Ubiquitination of Stat5A is recapitulated in a cell-free system, and Ubc5 is identified as the E2-conjugating enzyme for Stat5A ubiquitination. Interestingly, phosphorylation of Stat5A per se is not required for ubiquitination. Finally, C-terminal deletion analysis of Stat5A localizes the amphipathic region of amino acids 751-762 as a ubiquitination signal, possibly representing an E3 recognition motif. Taken together, these results demonstrate that the down-regulation of nuclear and cytoplasmic active Stat5A is differentially regulated. In the nucleus, ubiquitin/proteasome-mediated protein degradation is the dominant mechanism for the down-regulation of active Stat5A, whereas in the cytoplasm, protein tyrosine phasphatase is a major player in the down-regulation of active Stat5A.
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Affiliation(s)
- Yuhong Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, China
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Abstract
The high-affinity binding interactions between interferons (IFNs) and their cognate cell surface receptors lead to the activation of receptor-associated Janus protein tyrosine kinases (Jaks) and subsequent phosphorylation and activation of a group of transcription factors, the signal transducers and activators of transcription (Stats). Upon IFN-induced activation, these Stat proteins form homodimeric and heterodimeric complexes that translocate to the nucleus and bind specific elements within the promoters of IFN-stimulated genes (ISGs). In addition to the well-studied IFN-induced ISG factor 3 (ISGF3) and Stat1:1 complexes, IFNs induce the formation of a number of other Stat-containing complexes, including Stat3:3 and Stat5:5 homodimers, as well as Stat2:1 and Stat5:CrkL heterodimers, that also mediate gene transcription. Moreover, emerging evidence suggests that particular amino acid residues within the individual Stat proteins contribute to different aspects of Stat function. These residues modulate the transcriptional activation potential of Stat-containing complexes and thereby influence the expression of ISGs. Indeed, the Stat proteins function in a multifaceted manner to regulate the expression of proteins that mediate IFN responses.
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Affiliation(s)
- Melissa M Brierley
- Division of Cell & Molecular Biology, Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario M5G 2M1, Canada
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Abstract
Prolactin (PRL) and growth hormone (GH) act by way of their receptors as either hormones (systemically) or cytokines (locally). The Jak2/Stat5 pathway is the principal route by which PRL/GH activate target genes. The availability of knockout mice for each member of this signaling cascade has provided opportunities to understand their unique interactions. Jak2 is important in alternative signal transduction schema such as the MAP kinase and PI3K/Akt pathways. The putative Jak2/RUSH pathway is based on the fact that RUSH mediates the ability of PRL to augment progesterone-dependent gene transcription. New evidence shows that suppressors, regulators, and degraders control Jak2/Stat5. This review focuses on the most recent advances in the field of PRL/GH signal transduction.
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Affiliation(s)
- Beverly S Chilton
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA
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42
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Abstract
Interaction of cytokines with their cognate receptors leads to the activation of latent transcription factors, the signal transducer and activator of transcription (STAT) proteins. Numerous studies have identified the critical roles played by STAT proteins in regulating cell proliferation, differentiation and survival. Consequently, the activity of STAT proteins is negatively regulated by a variety of different mechanisms, which include alternative splicing, covalent modifications, protein-protein interactions with negative regulatory proteins and proteolytic processing by proteases. Cleavage of STAT proteins by proteases results in the generation of C-terminally truncated proteins, called STATgamma, which lack the transactivation domain and behave as functional dominant-negative proteins. Currently, STATgamma isoforms have been identified for Stat3, Stat5a, Stat5b and Stat6 in different cellular contexts and biological processes. Evidence is mounting for the role of as yet unidentified serine proteases in the proteolytic processing of STAT proteins, although at least one cysteine protease, calpain is also known to cleave these STATs in platelets and mast cells. Recently, studies of acute myeloid leukaemia and cutaneous T cell lymphoma patients have revealed important roles for the aberrant expression of Stat3gamma and Stat5gamma proteins in the pathology of these diseases. Together, these findings indicate that proteolytic processing is an important mechanism in the regulation of STAT protein biological activity and provides a fertile area for future studies.
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Affiliation(s)
- Lisa Hendry
- Peter Gorer Department of Immunobiology, Programme in Infection and Immunity, King's College, London, UK
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Mitchell TJ, John S. Signal transducer and activator of transcription (STAT) signalling and T-cell lymphomas. Immunology 2005; 114:301-12. [PMID: 15720432 PMCID: PMC1782085 DOI: 10.1111/j.1365-2567.2005.02091.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Interaction of cytokines with their cognate receptors leads to the activation of latent transcription factors - the signal transducers and activators of transcription (STAT) proteins - whose biological activities ultimately regulate many critical aspects of cell growth, survival and differentiation. Dysregulation of the JAK-STAT pathway is frequently observed in many primary human tumours, reflecting the importance of this pathway in the maintenance of cellular integrity. Here we review the current progress in STAT structure and function, and the contribution of STAT signalling to the pathogenesis of T-cell lymphomas.
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Affiliation(s)
- Tracey J Mitchell
- Skin Tumour Unit, St John's Institute of Dermatology, King's College LondonLondon, UK
| | - Susan John
- Peter Gorer Department of Immunobiology, Programme in Infection and Immunity, King's College LondonLondon, UK
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Lu X, Nechushtan H, Ding F, Rosado MF, Singal R, Alizadeh AA, Lossos IS. Distinct IL-4-induced gene expression, proliferation, and intracellular signaling in germinal center B-cell-like and activated B-cell-like diffuse large-cell lymphomas. Blood 2004; 105:2924-32. [PMID: 15591113 DOI: 10.1182/blood-2004-10-3820] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Diffuse large B-cell lymphomas (DLBCLs) can be subclassified into germinal center B-cell (GCB)-like and activated B-cell (ABC)-like tumors characterized by long and short survival, respectively. In contrast to ABC-like DLBCL, GCB-like tumors exhibit high expression of components of the interleukin 4 (IL-4) signaling pathway and of IL-4 target genes such as BCL6 and HGAL, whose high expression independently predicts better survival. These observations suggest distinct activity of the IL-4 signaling pathway in DLBCL subtypes. Herein, we demonstrate similar IL-4 expression but qualitatively different IL-4 effects on GCB-like and ABC-like DLBCL. In GCB-like DLBCL, IL-4 induces expression of its target genes, activates signal transducers and activators of transcription 6 (STAT6) signaling, and increases cell proliferation. In contrast, in the ABC-like DLBCL, IL-4 activates AKT, decreases cell proliferation by cell cycle arrest, and does not induce gene expression due to aberrant Janus kinase (JAK)-STAT6 signaling attributed to STAT6 dephosphorylation. We found distinct expression profiles of tyrosine phosphatases in DLBCL subtypes and identified putative STAT6 tyrosine phosphatases-protein tyrosine phosphatase nonreceptor type 1 (PTPN1) and PTPN2, whose expression is significantly higher in ABC-like DLBCL. These differences in tyrosine phosphatase expression might underlie distinct expression profiles of some of the IL-4 target genes and could contribute to a different clinical outcome of patients with GCB-like and ABC-like DLBCLs.
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MESH Headings
- Active Transport, Cell Nucleus
- B-Lymphocytes/pathology
- B-Lymphocytes/physiology
- Cell Division/immunology
- Cell Nucleus/metabolism
- Cell Nucleus/pathology
- Gene Expression Regulation, Neoplastic
- Germinal Center/pathology
- Humans
- Interleukin-4/genetics
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/pathology
- Lymphoma, B-Cell/physiopathology
- Lymphoma, Large B-Cell, Diffuse/genetics
- Lymphoma, Large B-Cell, Diffuse/pathology
- Lymphoma, Large B-Cell, Diffuse/physiopathology
- Oligonucleotide Array Sequence Analysis
- Phosphorylation
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Protein Tyrosine Phosphatases/metabolism
- STAT6 Transcription Factor
- Signal Transduction/immunology
- Trans-Activators/metabolism
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Affiliation(s)
- Xiaoqing Lu
- Sylvester Comprehensive Cancer Center, Division of Hematology-Oncology, Department of Medicine, University of Miami, 1475 NW 12th Ave (D8-4), Miami, FL 33136, USA
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Vinkemeier U. Getting the message across, STAT! Design principles of a molecular signaling circuit. ACTA ACUST UNITED AC 2004; 167:197-201. [PMID: 15504906 PMCID: PMC2172545 DOI: 10.1083/jcb.200407163] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The STAT transcription factors, usually referred to as “latent cytoplasmic proteins,” have experienced a fundamental reevaluation of their dynamic properties. This review focuses on recent studies that have identified continuous transport factor–independent nucleocytoplasmic cycling of STAT1, STAT3, and STAT5 as a basic principle of cytokine signaling. In addition, molecular mechanisms that modulate flux rates or cause retention were recognized, and together these findings have provided novel insight into the rules of cellular signal processing.
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Affiliation(s)
- Uwe Vinkemeier
- Abteilung Zelluläre Signalverarbeitung, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Freie Universität Berlin, 13125 Berlin, Germany.
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46
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Abstract
The signal transducer and activator of transcription (STAT) proteins have initially been described as cytoplasmic proteins that enter the nucleus only after cytokine treatment of cells. Contrary to this assumption, it was demonstrated that STATs are constantly shuttling between nucleus and cytoplasm irrespective of cytokine stimulation. This happens both via carrier-dependent as well as carrier-independent transportation. Moreover, it was also recognized that cytokine stimulation triggers nuclear retention of dimeric STATs, rather than affecting the rate of nuclear import. In summary, it is increasingly being appreciated that STAT nucleocytoplasmic cycling determines the quality of cytokine signaling and also constitutes an important area for microbial intervention.
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Affiliation(s)
- Thomas Meyer
- Abteilung Zelluläre Signalverarbeitung, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Freie Universität, Berlin, Germany
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47
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Touche N, Schohn H, Bonnet C, Buisine J, Plénat F, Philippe C, Jonveaux P. Nucleolar localization of the carboxy-truncated form of the signal transducer and activator of transcription 5 (STAT5beta) detected in CML and AML5. Leukemia 2004; 18:1144-5. [PMID: 15085151 DOI: 10.1038/sj.leu.2403371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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48
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Marg A, Shan Y, Meyer T, Meissner T, Brandenburg M, Vinkemeier U. Nucleocytoplasmic shuttling by nucleoporins Nup153 and Nup214 and CRM1-dependent nuclear export control the subcellular distribution of latent Stat1. J Cell Biol 2004; 165:823-33. [PMID: 15210729 PMCID: PMC2172394 DOI: 10.1083/jcb.200403057] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Accepted: 05/07/2004] [Indexed: 01/02/2023] Open
Abstract
Interferon stimulation of cells leads to the tyrosine phosphorylation of latent Stat1 and subsequent transient accumulation in the nucleus that requires canonical transport factors. However, the mechanisms that control the predominantly cytoplasmic localization in unstimulated cells have not been resolved. We uncovered that constitutive energy- and transport factor-independent nucleocytoplasmic shuttling is a property of unphosphorylated Stat1, Stat3, and Stat5. The NH(2)- and COOH-terminal Stat domains are generally dispensable, whereas alkylation of a single cysteine residue blocked cytokine-independent nuclear translocation and thus implicated the linker domain into the cycling of Stat1. It is revealed that constitutive nucleocytoplasmic shuttling of Stat1 is mediated by direct interactions with the FG repeat regions of nucleoporin 153 and nucleoporin 214 of the nuclear pore. Concurrent active nuclear export by CRM1 created a nucleocytoplasmic Stat1 concentration gradient that is significantly reduced by the blocking of energy-requiring translocation mechanisms or the specific inactivation of CRM1. Thus, we propose that two independent translocation pathways cooperate to determine the steady-state distribution of Stat1.
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Affiliation(s)
- Andreas Marg
- Abteilung Zellulare Signalverarbeitung, Leibniz-Forschungsinstitut fur Molekulare Pharmakologie, Robert-Rossle-Str. 10, 13125 Berlin, Germany
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49
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Pranada AL, Metz S, Herrmann A, Heinrich PC, Müller-Newen G. Real Time Analysis of STAT3 Nucleocytoplasmic Shuttling. J Biol Chem 2004; 279:15114-23. [PMID: 14701810 DOI: 10.1074/jbc.m312530200] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The transcription factor STAT3 is most important for the signal transduction of interleukin-6 and related cytokines. Upon stimulation cytoplasmic STAT3 is phosphorylated at tyrosine 705, translocates into the nucleus, and induces target genes. Notably, STAT proteins are also detectable in the nuclei of unstimulated cells. In this report we introduce a new method for the real time analysis of STAT3 nucleocytoplasmic shuttling in living cells which is based on the recently established fluorescence localization after photobleaching (FLAP) approach. STAT3 was C-terminally fused with the cyan (CFP) and yellow (YFP) variants of the green fluorescent protein. In the resulting STAT3-CFP-YFP (STAT3-CY) fusion protein the YFP can be selectively bleached using the 514-nm laser of a confocal microscope. This setting allows studies on the dynamics of STAT3 nucleocytoplasmic transport by monitoring the subcellular distribution of fluorescently labeled and selectively bleached STAT3-CY. By this means we demonstrate that STAT3-CY shuttles continuously between the cytosol and the nucleus in unstimulated cells. This constitutive shuttling does not depend on the phosphorylation of tyrosine 705 because a STAT3(Y705F)-CY mutant shuttles to the same extent as STAT3-CY. Experiments with deletion mutants reveal that the N-terminal moiety of STAT3 is essential for shuttling. Further studies suggest that a decrease in STAT3 nuclear export contributes to the nuclear accumulation of STAT3 in response to cytokine stimulation. The new approach presented in this study is generally applicable to any protein of interest for analyzing nucleocytoplasmic transport mechanisms in real time.
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Affiliation(s)
- Albert L Pranada
- Institut für Biochemie, Universitätsklinikum Rheinisch-Westfälische Technische Hochschule Aachen, Pauwelsstrasse 30, Aachen 52057, Germany
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Abstract
The IL (interleukin)-6-type cytokines IL-6, IL-11, LIF (leukaemia inhibitory factor), OSM (oncostatin M), ciliary neurotrophic factor, cardiotrophin-1 and cardiotrophin-like cytokine are an important family of mediators involved in the regulation of the acute-phase response to injury and infection. Besides their functions in inflammation and the immune response, these cytokines play also a crucial role in haematopoiesis, liver and neuronal regeneration, embryonal development and fertility. Dysregulation of IL-6-type cytokine signalling contributes to the onset and maintenance of several diseases, such as rheumatoid arthritis, inflammatory bowel disease, osteoporosis, multiple sclerosis and various types of cancer (e.g. multiple myeloma and prostate cancer). IL-6-type cytokines exert their action via the signal transducers gp (glycoprotein) 130, LIF receptor and OSM receptor leading to the activation of the JAK/STAT (Janus kinase/signal transducer and activator of transcription) and MAPK (mitogen-activated protein kinase) cascades. This review focuses on recent progress in the understanding of the molecular mechanisms of IL-6-type cytokine signal transduction. Emphasis is put on the termination and modulation of the JAK/STAT signalling pathway mediated by tyrosine phosphatases, the SOCS (suppressor of cytokine signalling) feedback inhibitors and PIAS (protein inhibitor of activated STAT) proteins. Also the cross-talk between the JAK/STAT pathway with other signalling cascades is discussed.
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