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Shang J, Previs SF, Conarello S, Chng K, Zhu Y, Souza SC, Staup M, Chen Y, Xie D, Zycband E, Schlessinger K, Johnson VP, Arreaza G, Liu F, Levitan D, Wang L, van Heek M, Erion M, Wang Y, Kelley DE. Phenotyping of adipose, liver, and skeletal muscle insulin resistance and response to pioglitazone in spontaneously obese rhesus monkeys. Am J Physiol Endocrinol Metab 2017; 312:E235-E243. [PMID: 28143858 DOI: 10.1152/ajpendo.00398.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 01/23/2017] [Accepted: 01/23/2017] [Indexed: 01/29/2023]
Abstract
Insulin resistance and diabetes can develop spontaneously with obesity and aging in rhesus monkeys, highly similar to the natural history of obesity, insulin resistance, and progression to type 2 diabetes in humans. The current studies in obese rhesus were undertaken to assess hepatic and adipose contributions to systemic insulin resistance-currently, a gap in our knowledge-and to benchmark the responses to pioglitazone (PIO). A two-step hyperinsulinemic-euglycemic clamp, with tracer-based glucose flux estimates, was used to measure insulin resistance, and in an intervention study was repeated following 6 wk of PIO treatment (3 mg/kg). Compared with lean healthy rhesus, obese rhesus has a 60% reduction of glucose utilization during a high insulin infusion and markedly impaired suppression of lipolysis, which was evident at both low and high insulin infusion. However, obese dysmetabolic rhesus manifests only mild hepatic insulin resistance. Six-week PIO treatment significantly improved skeletal muscle and adipose insulin resistance (by ~50%). These studies strengthen the concept that insulin resistance in obese rhesus closely resembles human insulin resistance and indicate the value of obese rhesus for appraising new insulin-sensitizing therapeutics.
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Affiliation(s)
- Jin Shang
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | | | | | - Keefe Chng
- Crown Bioscience, Incorporated, Kannapolis, North Carolina
| | - Yonghua Zhu
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | - Sandra C Souza
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | - Michael Staup
- Crown Bioscience, Incorporated, Kannapolis, North Carolina
| | - Ying Chen
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | - Dan Xie
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | | | | | | | - Gladys Arreaza
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | - Franklin Liu
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | - Diane Levitan
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | - Liangsu Wang
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | | | - Mark Erion
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
| | - Yixin Wang
- Crown Bioscience, Incorporated, Kannapolis, North Carolina
| | - David E Kelley
- Merck & Company, Incorporated, Kenilworth, New Jersey; and
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Schlessinger K, Li W, Tan Y, Liu F, Souza SC, Tozzo E, Liu K, Thompson JR, Wang L, Muise ES. Gene expression in WAT from healthy humans and monkeys correlates with FGF21-induced browning of WAT in mice. Obesity (Silver Spring) 2015; 23:1818-29. [PMID: 26308478 DOI: 10.1002/oby.21153] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/06/2015] [Accepted: 04/21/2015] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Identify a gene expression signature in white adipose tissue (WAT) that reports on WAT browning and is associated with a healthy phenotype. METHODS RNA from several different adipose depots across three species were analyzed by whole transcriptome profiling, including 1) mouse subcutaneous white fat, brown fat, and white fat after in vivo treatment with FGF21; 2) human subcutaneous and omental fat from insulin-sensitive and insulin-resistant patients; and 3) rhesus monkey subcutaneous fat from healthy and dysmetabolic individuals. RESULTS A "browning" signature in mice was identified by cross-referencing the FGF21-induced signature in WAT with the brown adipose tissue (BAT) vs. WAT comparison. In addition, gene expression levels in WAT from insulin-sensitive/healthy vs. insulin-resistant/dysmetabolic humans and rhesus monkeys, respectively, correlated with the gene expression levels in mouse BAT vs. WAT. A subset of 49 genes were identified that were consistently regulated or differentially expressed in the mouse and human data sets that could be used to monitor browning of WAT across species. CONCLUSIONS Gene expression profiles of WATs from healthy insulin-sensitive individuals correlate with those of BAT and FGF21-induced browning of WAT.
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Affiliation(s)
- Karni Schlessinger
- Department of Diabetes, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - Wenyu Li
- Department of Diabetes, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - Yejun Tan
- Department of Genetics and Pharmacogenomics, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - Franklin Liu
- Department of Diabetes, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - Sandra C Souza
- Department of Diabetes, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - Effie Tozzo
- Department of Diabetes, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - Kevin Liu
- Department of Diabetes, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - John R Thompson
- Department of Genetics and Pharmacogenomics, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - Liangsu Wang
- Department of Diabetes, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
| | - Eric S Muise
- Department of Genetics and Pharmacogenomics, Early Development and Discovery Sciences, Merck Research Laboratories, Merck Sharp & Dohme Corp., Kenilworth, New Jersey, USA
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Abstract
Signal transducer and activator of transcription 3 (STAT3) is a latent cytoplasmic transcription factor responsive to cytokine signaling and tyrosine kinase oncoproteins by nuclear translocation when it is tyrosine-phosphorylated. We report that malignant transformation by activated Ras is impaired without STAT3, in spite of the inability of Ras to drive STAT3 tyrosine phosphorylation or nuclear translocation. Moreover, STAT3 mutants that cannot be tyrosine-phosphorylated, that are retained in the cytoplasm, or that cannot bind DNA nonetheless supported Ras-mediated transformation. Unexpectedly, STAT3 was detected within mitochondria, and exclusive targeting of STAT3 to mitochondria without nuclear accumulation facilitated Ras transformation. Mitochondrial STAT3 sustained altered glycolytic and oxidative phosphorylation activities characteristic of cancer cells. Thus, in addition to its nuclear transcriptional role, STAT3 regulates a metabolic function in mitochondria, supporting Ras-dependent malignant transformation.
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Affiliation(s)
- Daniel J Gough
- Department of Pathology and New York University Cancer Institute, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
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Abstract
Wnt ligands and their receptors orchestrate many essential cellular and physiological processes. During development they control differentiation, proliferation, migration, and patterning, while in the adult, they regulate tissue homeostasis, primarily through their effects on stem cell proliferation and differentiation. Underpinning these diverse biological activities is a complex set of intracellular signaling pathways that are still poorly understood. Rho GTPases have emerged as key mediators of Wnt signals, most notably in the noncanonical pathways that involve polarized cell shape changes and migrations, but also more recently in the canonical pathway leading to beta-catenin-dependent transcription. It appears that Rho GTPases integrate Wnt-induced signals spatially and temporally to promote morphological and transcriptional changes affecting cell behavior.
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Affiliation(s)
- Karni Schlessinger
- Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.
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Abstract
Scratch-induced disruption of cultured monolayers induces polarity in front row cells that can be visualized by spatially localized polymerization of actin at the front of the cell and reorientation of the centrosome/Golgi to face the leading edge. We previously reported that centrosomal reorientation and microtubule polarization depend on a Cdc42-regulated signal transduction pathway involving activation of the Par6/aPKC complex followed by inhibition of GSK-3β and accumulation of the adenomatous polyposis coli (APC) protein at the plus ends of leading-edge microtubules. Using monolayers of primary rodent embryo fibroblasts, we show here that dishevelled (Dvl) and axin, two major components of the Wnt signaling pathway are required for centrosome reorientation and that Wnt5a is required for activation of this pathway. We conclude that disruption of cell–cell contacts leads to the activation of a noncanonical Wnt/dishevelled signal transduction pathway that cooperates with Cdc42/Par6/aPKC to promote polarized reorganization of the microtubule cytoskeleton.
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Affiliation(s)
- Karni Schlessinger
- Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research UK Oncogene and Signal Transduction Group and Department of Biochemistry and Molecular Biology, University College London, London, England, UK
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Zhang L, Badgwell DB, Bevers JJ, Schlessinger K, Murray PJ, Levy DE, Watowich SS. IL-6 signaling via the STAT3/SOCS3 pathway: functional analysis of the conserved STAT3 N-domain. Mol Cell Biochem 2006; 288:179-89. [PMID: 16718380 PMCID: PMC2441693 DOI: 10.1007/s11010-006-9137-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 01/17/2006] [Indexed: 10/24/2022]
Abstract
The conserved N-domain of the STAT proteins has been implicated in several activities crucial to cytokine signaling including receptor recruitment and STAT activation, cooperative DNA binding and STAT-dependent gene expression. We evaluated the role of the STAT3 N-domain in the IL-6 signal transduction pathway leading to Socs3 gene expression, an essential mechanism that controls the quality and magnitude of IL-6-dependent transcriptional responses. Based on the model for STAT N-domain function in cooperative gene expression and the presence of tandem STAT binding motifs in the murine Socs3 promoter, we anticipated that stabilizing interactions between adjacent STAT3 dimers via N-domain sequences might be essential for Socs3 gene expression. This was underscored by the tight conservation in the location and sequence of the tandem STAT binding sites between the murine and human Socs3 promoters. Using reconstitution into Stat3-/- mouse embryonic fibroblasts (Stat3-/- MEFs), we find that a STAT3 N-domain deletion mutant (Delta 133STAT3) is activated by tyrosine phosphorylation in response to IL-6 and then undergoes dephosphorylation with kinetics similar to full-length STAT3. These results highlight important differences compared to other STATs where the N-domain has been shown to mediate activation (STAT4) or dephosphorylation (STAT1). STAT3 binds predominantly to a single STAT consensus site in the Socs3 promoter, despite the presence of an adjacent STAT motif. Significantly, Delta 133STAT3 stimulates expression of the endogenous Socs3 gene in Stat3-/- MEFs upon IL-6 treatment with an activity similar to reconstituted STAT3, demonstrating that the N-domain is dispensable for Socs3 gene expression. We propose that the Socs3 gene in its chromosomal context is activated by the IL-6/STAT3 pathway independent of STAT3 N-domain sequences.
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Affiliation(s)
- Ling Zhang
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Donna B. Badgwell
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
- The Graduate School of Biomedical Sciences, University of Texas, Houston, Texas 77030
| | - Jack J. Bevers
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
- The Graduate School of Biomedical Sciences, University of Texas, Houston, Texas 77030
| | - Karni Schlessinger
- New York University School of Medicine, New York, NY 10016
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT
| | - Peter J. Murray
- Department of Infectious Diseases, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - David E. Levy
- New York University School of Medicine, New York, NY 10016
| | - Stephanie S. Watowich
- Department of Immunology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
- The Graduate School of Biomedical Sciences, University of Texas, Houston, Texas 77030
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Inghirami G, Chiarle R, Simmons WJ, Piva R, Schlessinger K, Levy DE. New and old functions of STAT3: a pivotal target for individualized treatment of cancer. Cell Cycle 2005; 4:1131-3. [PMID: 16082218 DOI: 10.4161/cc.4.9.1985] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Signal transducers and activators of transcription (STAT) regulate a plethora of cytokine responses. Recently, aberrant signaling by STAT proteins has been demonstrated to play important roles in the pathogenesis of many neoplasms, by promoting cell cycle progression and survival, stimulating angiogenesis, and impairing immunological responses and tumor surveillance. We have developed genetic tools to evaluate STAT-dependent malignancy and showed that survival and growth of lymphoid malignancies requires expression of STAT3. In contrast, loss of STAT3 in normal cells does not impair their growth or survival; but in spite of this apparent dispensability of STAT3, STAT3-null fibroblasts are resistant to transformation by a variety of oncogenes. The precise molecular mechanisms responsible for the tumorigenic activity of STAT3 have been only partially elucidated. While the tyrosine phosphorylation of STAT3, which is indicative of its signal-dependent activation, is a common occurrence in tumors, and appears to play a crucial role in some malignancies, a variety of new data suggest that it can be dispensable under some circumstances and STAT3 can participate in transformation through novel and non-canonical mechanisms. The discovery and dissection of non-canonical modes of STAT3 action will open new avenues for the design of effective therapeutics capable of neutralizing the tumorigenic properties of this molecule.
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Affiliation(s)
- Giorgio Inghirami
- Department of Pathology, NYU Cancer Institute, New York University School of Medicine, New York, New York 10016, USA.
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Abstract
Signal transducer and activator of transcription 3 (STAT3) has been indirectly implicated in numerous fundamental cellular processes, including proliferation, survival, and differentiation. We provide genetic evidence from studies of STAT3-null cells that STAT3 is dispensable for normal growth of mouse fibroblasts in culture. STAT3 contributed to the full induction of some (typified by c-fos) but not all (typified by c-myc) immediate early gene expression, but STAT3-independent processes were sufficient to support full cell growth and survival. However, STAT3 was required to manifest a transformed state following expression of v-src, and STAT3-null cells were impaired for anchorage-independent growth as colonies in soft agar and as tumors in mice. The data suggest that STAT3 mediates the maintenance of focal adhesion kinase activity in the absence of cell adhesion by suppressing the action of an inhibitory phosphatase.
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Yang J, Chatterjee-Kishore M, Staugaitis SM, Nguyen H, Schlessinger K, Levy DE, Stark GR. Novel roles of unphosphorylated STAT3 in oncogenesis and transcriptional regulation. Cancer Res 2005; 65:939-47. [PMID: 15705894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Signal transducer and activator of transcription 3 (STAT3) is phosphorylated on tyrosine residue 705 in response to growth factors or cytokines to form activated homodimers that drive gene expression. Because the stat3 promoter has a binding site for STAT3 dimers, the amount of STAT3 protein increases when STAT3 is activated (e.g., in response to interleukin 6). Unphosphorylated STAT1 is known to drive the expression of certain genes. To explore the possibility of a similar role for the induced expression of unphosphorylated STAT3, we overexpressed either Y705F STAT3, which can not be phosphorylated on residue 705, or wild-type STAT3 in normal human mammary epithelial cells or STAT3-null mouse cells. The levels of many mRNAs were affected strongly by high levels of either form of STAT3. Some genes whose expression was increased by overexpressed STAT3, but not by activated STAT3 dimers, encode well-known oncoproteins (e.g., MRAS and MET). In many tumors, STAT3 is activated constitutively, and thus the unphosphorylated form is likely to be expressed highly, driving oncogene expression by a novel mechanism. In addition, expression of the stat3 gene is increased strongly in response to interleukin 6, and the high levels of unphosphorylated STAT3 that result drive a substantial late phase of gene expression in response to this cytokine. Thus, unphosphorylated STAT3, which activates gene expression by a novel mechanism distinct from that used by STAT3 dimers, is very likely to be an important transcription factor both in cancer and in responses to cytokines.
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Affiliation(s)
- Jinbo Yang
- Department of Molecular Biology, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio, USA
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10
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Yang J, Chatterjee-Kishore M, Staugaitis SM, Nguyen H, Schlessinger K, Levy DE, Stark GR. Novel Roles of Unphosphorylated STAT3 in Oncogenesis and Transcriptional Regulation. Cancer Res 2005. [DOI: 10.1158/0008-5472.939.65.3] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Signal transducer and activator of transcription 3 (STAT3) is phosphorylated on tyrosine residue 705 in response to growth factors or cytokines to form activated homodimers that drive gene expression. Because the stat3 promoter has a binding site for STAT3 dimers, the amount of STAT3 protein increases when STAT3 is activated (e.g., in response to interleukin 6). Unphosphorylated STAT1 is known to drive the expression of certain genes. To explore the possibility of a similar role for the induced expression of unphosphorylated STAT3, we overexpressed either Y705F STAT3, which can not be phosphorylated on residue 705, or wild-type STAT3 in normal human mammary epithelial cells or STAT3-null mouse cells. The levels of many mRNAs were affected strongly by high levels of either form of STAT3. Some genes whose expression was increased by overexpressed STAT3, but not by activated STAT3 dimers, encode well-known oncoproteins (e.g., MRAS and MET). In many tumors, STAT3 is activated constitutively, and thus the unphosphorylated form is likely to be expressed highly, driving oncogene expression by a novel mechanism. In addition, expression of the stat3 gene is increased strongly in response to interleukin 6, and the high levels of unphosphorylated STAT3 that result drive a substantial late phase of gene expression in response to this cytokine. Thus, unphosphorylated STAT3, which activates gene expression by a novel mechanism distinct from that used by STAT3 dimers, is very likely to be an important transcription factor both in cancer and in responses to cytokines.
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Affiliation(s)
| | | | - Susan M. Staugaitis
- 2Department of Neurosciences, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio and
| | | | - Karni Schlessinger
- 3Department of Pathology, New York University School of Medicine, New York, New York
| | - David E. Levy
- 3Department of Pathology, New York University School of Medicine, New York, New York
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Shen Y, Schlessinger K, Zhu X, Meffre E, Quimby F, Levy DE, Darnell JE. Essential role of STAT3 in postnatal survival and growth revealed by mice lacking STAT3 serine 727 phosphorylation. Mol Cell Biol 2004; 24:407-19. [PMID: 14673173 PMCID: PMC303338 DOI: 10.1128/mcb.24.1.407-419.2004] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A large number of extracellular polypeptides bound to their cognate receptors activate the transcription factor STAT3 by phosphorylation of tyrosine 705. Supplemental activation occurs when serine 727 is also phosphorylated. STAT3 deletion in mice leads to embryonic lethality. We have produced mice with alanine substituted for serine 727 in STAT3 (the SA allele) to examine the function of serine 727 phosphorylation in vivo. Embryonic fibroblasts from SA/SA mice had approximately 50% of the transcriptional response of wild-type cells. However, SA/SA mice were viable and grossly normal. STAT3 wild-type/null (+/-) animals were also normal and were interbred with SA/SA mice to study SA/- mice. The SA/- mice progressed through gestation, showing 10 to 15% reduced birth weight, three-fourths died soon after birth, and the SA/- survivors reached only 50 to 60% of normal size at 1 week of age. The lethality and decreased growth were accompanied by altered insulin-like growth factor 1 (IGF-1) levels in serum, establishing a role for the STAT3 serine phosphorylation acting through IGF-1 in embryonic and perinatal growth. The SA/- survivors have decreased thymocyte number associated with increased apoptosis, but unexpectedly normal STAT3-dependent liver acute phase response. These animals offer the opportunity to study defined reductions in the transcriptional capacity of a widely used signaling pathway.
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Affiliation(s)
- Yuhong Shen
- Laboratory of Molecular Cell Biology, The Rockefeller University, New York, New York 10021, USA
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Bertolotti A, Wang X, Novoa I, Jungreis R, Schlessinger K, Cho JH, West AB, Ron D. Increased sensitivity to dextran sodium sulfate colitis in IRE1beta-deficient mice. J Clin Invest 2001; 107:585-93. [PMID: 11238559 PMCID: PMC199427 DOI: 10.1172/jci11476] [Citation(s) in RCA: 319] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The epithelial cells of the gastrointestinal tract are exposed to toxins and infectious agents that can adversely affect protein folding in the endoplasmic reticulum (ER) and cause ER stress. The IRE1 genes are implicated in sensing and responding to ER stress signals. We found that epithelial cells of the gastrointestinal tract express IRE1beta, a specific isoform of IRE1. BiP protein, a marker of ER stress, was elevated in the colonic mucosa of IRE1beta(-/-) mice, and, when exposed to dextran sodium sulfate (DSS) to induce inflammatory bowel disease, mutant mice developed colitis 3-5 days earlier than did wild-type or IRE1beta(+/-) mice. The inflammation marker ICAM-1 was also expressed earlier in the colonic mucosa of DSS-treated IRE1beta(-/-) mice, indicating that the mutation had its impact early in the inflammatory process, before the onset of mucosal ulceration. These findings are consistent with a model whereby perturbations in ER function, which are normally mitigated by the activity of IRE1beta, participate in the development of colitis.
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Affiliation(s)
- A Bertolotti
- Skirball Institute of Biomolecular Medicine, Departments of Medicine and Cell Biology, and the Kaplan Cancer Center, New York University School of Medicine, New York, New York, USA
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14
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Philosof-Oppenheimer R, Hampe CS, Schlessinger K, Fridkin M, Pecht I. An immunoreceptor tyrosine-based inhibitory motif, with serine at site Y-2, binds SH2-domain-containing phosphatases. Eur J Biochem 2000; 267:703-11. [PMID: 10651806 DOI: 10.1046/j.1432-1327.2000.01044.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Clustering of the mast cell function-associated antigen by its specific monoclonal antibody (G63) inhibits the FcepsilonRI-mediated secretory response. The cytosolic tail of the mast cell function-associated antigen contains a SIYSTL stretch, a potential immunoreceptor tyrosine-based inhibition motif. To investigate the possible functional role of this sequence, as well as identify potential intracellular proteins that interact with it, peptides corresponding to residues 4-12 of the mast cell function-associated antigen's N-terminal cytoplasmic domain, containing the above motif, were synthesized and used in affinity chromatography of mast cell lysates. Both tyrosyl phosphorylated and thiophosphorylated mast cell function-associated antigen peptides bound the src homology domain 2 (SH2)-containing tyrosine phosphatases-1 (SHP-1), -2 (SHP-2) and inositol 5'-phosphatase (SHIP), though with different efficiencies. Neither the nonphosphorylated peptide nor its tyrosyl phosphorylated reversed sequence peptide bound any of these phosphatases. Point mutation analysis of mast cell function-associated antigen pITIM binding requirements demonstrated that for SHP-2 association the amino acid residue at position Y-2 is not restricted to the hydrophobic isoleucine or valine. Glycine and other amino acids with hydrophilic residues, such as serine and threonine, at this position also maintain this binding capacity, whereas alanine and acidic residues abolish it. In contrast, SHP-1 binding was maintained only when serine was substituted by valine, suggesting that the Y-2 position provides selectivity for peptide binding to SH2 domains of SHP-1 and SHP-2. These results were corroborated by surface plasmon resonance measurements of the interaction between tyrosyl phosphorylated mast cell function-associated antigen peptide and recombinant soluble SH2 domains of SHP-1, SHP-2 and SHIP, suggesting that the associations observed in the cell lysates may be direct. Taken together these results clearly indicate that the SIYSTL motif present in mast cell function-associated antigen's cytosolic tail exhibits characteristic features of an immunoreceptor tyrosine-based inhibition motif, suggesting it is a new member of the growing diverse family of immunoreceptor tyrosine-based inhibition motif-containing receptors.
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Orzech E, Schlessinger K, Weiss A, Okamoto CT, Aroeti B. Interactions of the AP-1 Golgi adaptor with the polymeric immunoglobulin receptor and their possible role in mediating brefeldin A-sensitive basolateral targeting from the trans-Golgi network. J Biol Chem 1999; 274:2201-15. [PMID: 9890983 DOI: 10.1074/jbc.274.4.2201] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
We provide morphological, biochemical, and functional evidence suggesting that the AP-1 clathrin adaptor complex of the trans-Golgi network interacts with the polymeric immunoglobulin receptor in transfected Madin-Darby canine kidney cells. Our results indicate that immunofluorescently labeled gamma-adaptin subunit of the adaptor complex and the polymeric immunoglobulin receptor partially co-localize in polarized and semi-polarized cells. gamma-Adaptin is co-immunoisolated with membranes expressing the wild-type receptor. The entire AP-1 adaptor complex could be chemically cross-linked to the receptor in filter-grown cells. gamma-Adaptin could be co-immunoprecipitated with the wild-type receptor, with reduced efficiency with receptor mutant whose basolateral sorting motif has been deleted, and not with receptor lacking its cytoplasmic tail. Co-immunoprecipitation of gamma-adaptin was inhibited by brefeldin A. Mutation of cytoplasmic serine 726 inhibited receptor interactions with AP-1 but did not abrogate the fidelity of its basolateral targeting from the trans-Golgi network. However, the kinetics of receptor delivery to the basolateral cell surface were slowed by the mutation. Although surface delivery of the wild-type receptor was inhibited by brefeldin A, the delivery of the mutant receptor was insensitive to the drug. Our results are consistent with a working model in which phosphorylated cytoplasmic serine modulates the recruitment of the polymeric immunoglobulin receptor into AP-1/clathrin-coated areas in the trans-Golgi network. This process may regulate the efficiency of receptor targeting from the trans-Golgi network.
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Affiliation(s)
- E Orzech
- Department of Cell and Animal Biology, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel
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16
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Schlessinger K, Davidson C. Stretch your way to a healthier workday. Mater Manag Health Care 1996; 5:18, 20. [PMID: 10161328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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17
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