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Castillo-Sanchez R, Cortes-Reynosa P, Lopez-Perez M, Garcia-Hernandez A, Salazar EP. Caveolae Microdomains Mediate STAT5 Signaling Induced by Insulin in MCF-7 Breast Cancer Cells. J Membr Biol 2023; 256:79-90. [PMID: 35751654 DOI: 10.1007/s00232-022-00253-x] [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: 02/21/2022] [Accepted: 06/06/2022] [Indexed: 02/07/2023]
Abstract
Caveolae are small plasma membrane invaginations constituted for membrane proteins namely caveolins and cytosolic proteins termed cavins, which can occupy up to 50% of the surface of mammalian cells. The caveolae have been involved with a variety of cellular processes including regulation of cellular signaling. Insulin is a hormone that mediates a variety of physiological processes through activation of insulin receptor (IR), which is a tyrosine kinase receptor expressed in all mammalian tissues. Insulin induces activation of signal transducers and activators of transcription (STAT) family members including STAT5. In this study, we demonstrate, for the first time, that insulin induces phosphorylation of STAT5 at tyrosine-694 (STAT5-Tyr(P)694), STAT5 nuclear accumulation and an increase in STAT5-DNA complex formation in MCF-7 breast cancer cells. Insulin also induces nuclear accumulation of STAT5-Tyr(P)694, caveolin-1, and IR in MCF-7 cells. STAT5 nuclear accumulation and the increase of STAT5-DNA complex formation require the integrity of caveolae and microtubule network. Moreover, insulin induces an increase and nuclear accumulation of STAT5-Tyr(P)694 in MDA-MB-231 breast cancer cells. In conclusion, results demonstrate that caveolae and microtubule network play an important role in STAT5-Tyr(P)694, STAT5 nuclear accumulation and STAT5-DNA complex formation induced by insulin in breast cancer cells.
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Affiliation(s)
- Rocio Castillo-Sanchez
- Departamento de Biologia Celular, Cinvestav-IPN, Av. IPN # 2508, 07360, Mexico City, Mexico
| | - Pedro Cortes-Reynosa
- Departamento de Biologia Celular, Cinvestav-IPN, Av. IPN # 2508, 07360, Mexico City, Mexico
| | - Mario Lopez-Perez
- Departamento de Biologia Celular, Cinvestav-IPN, Av. IPN # 2508, 07360, Mexico City, Mexico
| | | | - Eduardo Perez Salazar
- Departamento de Biologia Celular, Cinvestav-IPN, Av. IPN # 2508, 07360, Mexico City, Mexico.
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Zhang Y, Zhang S, Guan W, Chen F, Cheng L, Lv Y, Chen J. GLUT1 and lactose synthetase are critical genes for lactose synthesis in lactating sows. Nutr Metab (Lond) 2018; 15:40. [PMID: 29946342 PMCID: PMC6001073 DOI: 10.1186/s12986-018-0276-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/07/2018] [Indexed: 11/10/2022] Open
Abstract
Background Lactose synthesis rate is an important factor in milk production and quality in mammals. Understanding the lactose synthesis mechanism is crucial for the improvement of milk quantity and quality. However, research on the temporal gene changes regarding lactose synthesis during the whole lactation is still limited. The objective of this study was to determine gene expression profiles related to lactose synthesis in sows during lactation, and further identify the critical steps or key factors in the lactose synthesis pathway. Methods To determine the temporal change of factors related to lactose synthesis in sows, milk from eight multiparous Yorkshire sows (parity 3 to 6) was collected at 0 h, 2 h, 6 h, 12 h, 24 h, day 2, 3, 4, 7, 14, and 21 after birth of the first piglet. Lactose content, prolactin and progesterone concentration, and gene or protein expression related to lactose synthesis were measured. Results The lactose yield increased gradually from D2 to D21 and reached a maximum at D14 (3-fold from D2) during lactation (P < 0.05). A similar trend was observed in IGF-1 and insulin concentrations in milk, both of which were greatest at D3 with a subsequent decrease during middle to late lactation. Conversely, milk prolactin and progesterone concentrations moderately decreased with the progression of lactation. The mRNA or protein expressions related to glucose transportation (GLUT1), glucose-galactose interconversion (HK1 and UGP2), UDP-galactose transportation (SLC35A2), and lactose synthetase (LALBA and B4GALT1) in the lactose synthesis pathway were significantly upregulated during early to middle lactation and plateaued by late lactation (P < 0.05). Conclusions These novel findings suggest that the increased lactose synthesis in lactation was related to the coordinated upregulation of genes or enzymes in the lactose synthesis pathway, and glucose transportation (GLUT1) and lactose synthetase (LALBA and B4GALT1) might be the critical steps in the lactose synthesis pathway of sows during lactation.
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Affiliation(s)
- Yinzhi Zhang
- 1Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Shihai Zhang
- 1Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Wutai Guan
- 1Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China.,2College of Animal Science and National Engineering Research Center for Breeding Swine Industry, South China Agricultural University, Wushan Avenue, Tianhe District, Guangzhou, 510642 China
| | - Fang Chen
- 1Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Lin Cheng
- 1Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Yantao Lv
- 1Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Jun Chen
- 1Guangdong Province Key Laboratory of Animal Nutrition Control, College of Animal Science, South China Agricultural University, Guangzhou, China
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3
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Nguyen LK, Kholodenko BN. Feedback regulation in cell signalling: Lessons for cancer therapeutics. Semin Cell Dev Biol 2016; 50:85-94. [DOI: 10.1016/j.semcdb.2015.09.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 09/28/2015] [Indexed: 02/06/2023]
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4
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Tsiplakou E, Flemetakis E, Kouri ED, Karalias G, Sotirakoglou K, Zervas G. The effect of long-term under- and overfeeding on the expression of six major milk proteins' genes in the mammary tissue of goats. J Anim Physiol Anim Nutr (Berl) 2015; 100:422-30. [PMID: 26613803 DOI: 10.1111/jpn.12394] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/29/2015] [Indexed: 01/09/2023]
Abstract
Milk protein synthesis in the mammary gland involves expression of six major milk proteins' genes whose nutritional regulation remains poorly defined. In this study, the effect of long-term under- and overfeeding on the expression of as1-casein: CSN1S1, as2-casein: CSN1S2, β-casein: CSN2, κ-casein: CSN3, α-lactalbumin: LALBA and β-lactoglobulin: BLG gene in goat mammary tissue (MT) was examined. Twenty-four lactating dairy goat, at 90-98 days in milk, were divided into three homogenous subgroups and fed the same ration, for 60 days, in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant decrease in mRNA of CSN1S2, CSN2, CSN3 and LALBA genes in the MT of underfed goats compared with the overfed and on the CSN1S1 and BLG gene expressions in the MT of underfed goats compared with the respective control and overfed. CSN2 was the most abundant transcript in goat MT relative to the other milk proteins' genes. Significantly positive correlations were observed between the mRNA levels of caseins' and BLG genes with the milk yield. Moreover, a significant correlation was found between the mRNA levels of CSN1S2 with the milk protein, lactose content and lactose yield and also between the LALBA gene expression with the lactose content and lactose yield respectively. In conclusion, the feeding level and consequently the nutrients availability affected the milk lactose content, protein and lactose yield as well as the milk volume by altering the CSN1S1, CSN1S2, CSN2, CSN3, LALBA and BLG gene expression involved in their metabolic pathways.
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Affiliation(s)
- E Tsiplakou
- Department of Nutritional Physiology and Feeding, Agricultural University of Athens, Athens, Greece
| | - E Flemetakis
- Department of Agricultural Biotechnology, Agricultural University of Athens, Athens, Greece
| | - E-D Kouri
- Department of Agricultural Biotechnology, Agricultural University of Athens, Athens, Greece
| | - G Karalias
- Department of Agricultural Biotechnology, Agricultural University of Athens, Athens, Greece
| | - K Sotirakoglou
- Departmentof Plant Breeding and Biometry, Agricultural University of Athens, Athens, Greece
| | - G Zervas
- Department of Nutritional Physiology and Feeding, Agricultural University of Athens, Athens, Greece
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5
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Gurzov EN, Tran M, Fernandez-Rojo MA, Merry TL, Zhang X, Xu Y, Fukushima A, Waters MJ, Watt MJ, Andrikopoulos S, Neel BG, Tiganis T. Hepatic oxidative stress promotes insulin-STAT-5 signaling and obesity by inactivating protein tyrosine phosphatase N2. Cell Metab 2014; 20:85-102. [PMID: 24954415 PMCID: PMC4335267 DOI: 10.1016/j.cmet.2014.05.011] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 03/23/2014] [Accepted: 04/28/2014] [Indexed: 12/18/2022]
Abstract
Hepatic insulin resistance is a key contributor to the pathogenesis of obesity and type 2 diabetes (T2D). Paradoxically, the development of insulin resistance in the liver is not universal, but pathway selective, such that insulin fails to suppress gluconeogenesis but promotes lipogenesis, contributing to the hyperglycemia, steatosis, and hypertriglyceridemia that underpin the deteriorating glucose control and microvascular complications in T2D. The molecular basis for the pathway-specific insulin resistance remains unknown. Here we report that oxidative stress accompanying obesity inactivates protein-tyrosine phosphatases (PTPs) in the liver to activate select signaling pathways that exacerbate disease progression. In obese mice, hepatic PTPN2 (TCPTP) inactivation promoted lipogenesis and steatosis and insulin-STAT-5 signaling. The enhanced STAT-5 signaling increased hepatic IGF-1 production, which suppressed central growth hormone release and exacerbated the development of obesity and T2D. Our studies define a mechanism for the development of selective insulin resistance with wide-ranging implications for diseases characterized by oxidative stress.
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Affiliation(s)
- Esteban N Gurzov
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Melanie Tran
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Manuel A Fernandez-Rojo
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Troy L Merry
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Xinmei Zhang
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Yang Xu
- Princess Margaret Cancer Center, University Health Network, 101 College Street, Toronto Medical Discovery Tower, University of Toronto, Toronto, ON M5G 1L7, Canada; Department of Medical Biophysics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Atsushi Fukushima
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Michael J Waters
- Institute for Molecular Bioscience, Services Road, University of Queensland, St. Lucia, QLD 4072, Australia
| | - Matthew J Watt
- Department of Physiology, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Sofianos Andrikopoulos
- Department of Medicine Heidelberg Repatriation Hospital, 300 Waterdale Road, Heidelberg West, The University of Melbourne, VIC 3081, Australia
| | - Benjamin G Neel
- Princess Margaret Cancer Center, University Health Network, 101 College Street, Toronto Medical Discovery Tower, University of Toronto, Toronto, ON M5G 1L7, Canada; Department of Medical Biophysics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Tony Tiganis
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800, Australia.
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Abstract
The insulin receptor (IR) is an important hub in insulin signaling and its activation is tightly regulated. Upon insulin stimulation, IR is activated through autophosphorylation, and consequently phosphorylates several insulin receptor substrate (IRS) proteins, including IRS1-6, Shc and Gab1. Certain adipokines have also been found to activate IR. On the contrary, PTP, Grb and SOCS proteins, which are responsible for the negative regulation of IR, are characterized as IR inhibitors. Additionally, many other proteins have been identified as IR substrates and participate in the insulin signaling pathway. To provide a more comprehensive understanding of the signals mediated through IR, we reviewed the upstream and downstream signal molecules of IR, summarized the positive and negative modulators of IR, and discussed the IR substrates and interacting adaptor proteins. We propose that the molecular events associated with IR should be integrated to obtain a better understanding of the insulin signaling pathway and diabetes.
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Affiliation(s)
- Yipeng Du
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
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Frias MA, Montessuit C. JAK-STAT signaling and myocardial glucose metabolism. JAKSTAT 2013; 2:e26458. [PMID: 24416656 PMCID: PMC3876426 DOI: 10.4161/jkst.26458] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 09/11/2013] [Accepted: 09/11/2013] [Indexed: 12/19/2022] Open
Abstract
JAK-STAT signaling occurs in virtually every tissue of the body, and so does glucose metabolism. In this review, we summarize the regulation of glucose metabolism in the myocardium and ponder whether JAK-STAT signaling participates in this regulation. Despite a paucity of data directly pertaining to cardiac myocytes, we conclude that JAK-STAT signaling may contribute to the development of insulin resistance in the myocardium in response to various hormones and cytokines.
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Affiliation(s)
- Miguel A Frias
- Division of Endocrinology, Diabetology and Nutrition; University of Geneva School of Medicine; Geneva, Switzerland
| | - Christophe Montessuit
- Division of Cardiology; Department of Medical Specialties; University of Geneva School of Medicine; Geneva, Switzerland
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Britschgi A, Andraos R, Brinkhaus H, Klebba I, Romanet V, Müller U, Murakami M, Radimerski T, Bentires-Alj M. JAK2/STAT5 inhibition circumvents resistance to PI3K/mTOR blockade: a rationale for cotargeting these pathways in metastatic breast cancer. Cancer Cell 2012; 22:796-811. [PMID: 23238015 DOI: 10.1016/j.ccr.2012.10.023] [Citation(s) in RCA: 191] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 10/08/2012] [Accepted: 10/31/2012] [Indexed: 01/15/2023]
Abstract
Hyperactive PI3K/mTOR signaling is prevalent in human malignancies and its inhibition has potent antitumor consequences. Unfortunately, single-agent targeted cancer therapy is usually short-lived. We have discovered a JAK2/STAT5-evoked positive feedback loop that dampens the efficacy of PI3K/mTOR inhibition. Mechanistically, PI3K/mTOR inhibition increased IRS1-dependent activation of JAK2/STAT5 and secretion of IL-8 in several cell lines and primary breast tumors. Genetic or pharmacological inhibition of JAK2 abrogated this feedback loop and combined PI3K/mTOR and JAK2 inhibition synergistically reduced cancer cell number and tumor growth, decreased tumor seeding and metastasis, and also increased overall survival of the animals. Our results provide a rationale for combined targeting of the PI3K/mTOR and JAK2/STAT5 pathways in triple-negative breast cancer, a particularly aggressive and currently incurable disease.
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Affiliation(s)
- Adrian Britschgi
- Friedrich Miescher Institute for Biomedical Research, Basel, CH-4058, Switzerland
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9
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Bionaz M, Loor JJ. Gene networks driving bovine mammary protein synthesis during the lactation cycle. Bioinform Biol Insights 2011; 5:83-98. [PMID: 21698073 PMCID: PMC3118679 DOI: 10.4137/bbi.s7003] [Citation(s) in RCA: 217] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A crucial role for both insulin and mTOR in the regulation of milk protein synthesis is emerging. Bovine mammary biopsies harvested during late-pregnancy through end of subsequent lactation were used to evaluate via quantitative PCR the expression of 44 genes involved in pathways of insulin, mTOR, AMPK, and Jak2-Stat5 signalling and also glucose and amino acid (AA) transporters. We observed an increased expression during lactation of ELF5, AA and glucose transporters, insulin signaling pathway components, MAPK14, FRAP1, EIF4EBP2, GSK3A and TSC1 among mTOR signaling-related genes. Among ribosomal components RPL22 was down-regulated. The overall data support a central role of AA and glucose transporters and insulin signaling through mTOR for the regulation of protein synthesis in bovine mammary gland. Furthermore, the existence of translational competition favoring the translation of milk protein transcripts was inferred from the combined dataset.
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Affiliation(s)
- Massimo Bionaz
- Mammalian NutriPhysio Genomics, Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA
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10
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Vijayakumar A, Novosyadlyy R, Wu Y, Yakar S, LeRoith D. Biological effects of growth hormone on carbohydrate and lipid metabolism. Growth Horm IGF Res 2010; 20:1-7. [PMID: 19800274 PMCID: PMC2815161 DOI: 10.1016/j.ghir.2009.09.002] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 09/01/2009] [Accepted: 09/04/2009] [Indexed: 01/05/2023]
Abstract
This review will summarize the metabolic effects of growth hormone (GH) on the adipose tissue, liver, and skeletal muscle with focus on lipid and carbohydrate metabolism. The metabolic effects of GH predominantly involve the stimulation of lipolysis in the adipose tissue resulting in an increased flux of free fatty acids (FFAs) into the circulation. In the muscle and liver, GH stimulates triglyceride (TG) uptake, by enhancing lipoprotein lipase (LPL) expression, and its subsequent storage. The effects of GH on carbohydrate metabolism are more complicated and may be mediated indirectly via the antagonism of insulin action. Furthermore, GH has a net anabolic effect on protein metabolism although the molecular mechanisms of its actions are not completely understood. The major questions that still remain to be answered are (i) What are the molecular mechanisms by which GH regulates substrate metabolism? (ii) Does GH affect substrate metabolism directly or indirectly via IGF-1 or antagonism of insulin action?
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Affiliation(s)
- Archana Vijayakumar
- Division of Endocrinology, Diabetes and Bone Diseases, The Samuel Bronfman Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA
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Story DJ, Stephens JM. Modulation and lack of cross-talk between signal transducer and activator of transcription 5 and Suppressor of cytokine signaling-3 in insulin and growth hormone signaling in 3T3-L1 adipocytes. Obesity (Silver Spring) 2006; 14:1303-11. [PMID: 16988072 DOI: 10.1038/oby.2006.148] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To examine the role of signal transducer and activator of transcription (STAT) 5 and suppressor of cytokine signaling (SOCS)-3 in the cross-talk between growth hormone and insulin (INS) signaling in fat cells. RESEARCH METHODS AND PROCEDURES Fully differentiated 3T3-L1 adipocytes were exposed to INS, growth hormone (GH), or both of these growth factors, and the activation of STAT5 proteins and mitogen-activated protein kinase was examined using phospho-specific antibodies. The induction of SOCS-3 mRNA was assessed by Northern blot analysis. INS-stimulated glucose transport was also measured. RESULTS We observed that GH, not INS, induced STAT5 activation in adipocytes in a manner that was independent of extracellular signal-regulated kinase (ERK) activation or new protein synthesis. GH strongly induced SOCS-3 mRNA expression, whereas INS had a much less potent effect on SOCS-3 mRNA expression. Because SOCS-3 has been implicated in the attenuation of GH and INS signaling, we examined the cross-talk between these signaling pathways. GH pretreatment of adipocytes inhibited GH signaling. Similarly, INS pretreatment inhibited INS signaling. However, INS did not block the GH-induced activation of STAT5, and GH did not block the INS induction of ERK activity or of increased glucose uptake. We observed that neither new protein synthesis nor activation of ERKs 1 and 2 were required for the inhibition of GH signaling. DISCUSSION These results demonstrate that blocking the induction of the SOCS-3 protein has no effect on the attenuation of GH signaling and support recent studies suggesting that SOCS proteins have additional functions. In addition, these studies demonstrate that GH-induced SOCS-3 expression is insufficient to inhibit INS-induced glucose uptake in adipocytes.
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Affiliation(s)
- David J Story
- Department of Biological Sciences, Louisiana State University, 202 Life Sciences Building, Baton Rouge, LA 70803, USA
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Avissar NE, Toia L, Sax HC. Epidermal growth factor and/or growth hormone induce differential, side-specific signal transduction protein phosphorylation in enterocytes. JPEN J Parenter Enteral Nutr 2006; 29:322-35; discussion 335-6. [PMID: 16107595 DOI: 10.1177/0148607105029005322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Epidermal growth factor (EGF) plus growth hormone (GH) enhances luminal glutamine transport into rabbit and human intestinal cells. Our objective was to screen for activation status of signal proteins in C2(BBe)1 cells (enterocyte-like cell line) in response to side-specific EGF or GH treatment and to investigate the dependence of EGF receptor (EGFR) phosphorylation status on its tyrosine kinase. METHODS C2(BBe)1 cells on Transwells were treated for 15 minutes on either the basolateral or apical-side with EGF or GH. Lysates underwent Kinetworks phospho site-screen-2.1 analysis (duplicate experiments). In addition, lysates from cells treated as above with or without tyrphostin AG1478 (a specific EGFR tyrosine kinase inhibitor) underwent Western blot analysis for total EGFR and EGFR phosphorylated on tyrosine 1173, 1086 or 1068 (4-7 experiments). RESULTS Kinetworks phospho-screening demonstrated a broad range of interactions dependent on both side of exposure and protein studied. From this screen, it appears that ErbB2, Met, and insulin receptor (R)/insulin-like growth factor 1 R are not involved in the growth factors signals. For EGFR phosphorylation, basolateral, but not apical, EGF was a strong activator. Synergism was seen, but only with apical EGF plus basolateral GH. All EGFR phosphorylations were EGFR tyrosine kinase dependent. In contradistinction, apical EGF phosphorylated FAK and MAPKs. CONCLUSIONS Kinetworks phosphoprotein screens can suggest pathways involved in side-specific and synergistic interaction between EGF and GH. For EGFR, synergism by EGF + GH was noticed only with Ap EGF plus Bl GH and was EGFR tyrosine kinase dependent. Adaptive intestinal responses due to enterally administrated EGF might be accelerated by the availability of parenteral GH.
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Affiliation(s)
- Nelly E Avissar
- University of Rochester School of Medicine and Dentistry, Department of Surgery, Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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13
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Zhang W, Zong CS, Hermanto U, Lopez-Bergami P, Ronai Z, Wang LH. RACK1 recruits STAT3 specifically to insulin and insulin-like growth factor 1 receptors for activation, which is important for regulating anchorage-independent growth. Mol Cell Biol 2006; 26:413-24. [PMID: 16382134 PMCID: PMC1346890 DOI: 10.1128/mcb.26.2.413-424.2006] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 06/03/2005] [Accepted: 10/20/2005] [Indexed: 01/30/2023] Open
Abstract
Current understanding of the activation of STATs is through binding between the SH2 domain of STATs and phosphotyrosine of tyrosine kinases. Here we demonstrate a novel role of RACK1 as an adaptor for insulin and insulin-like growth factor 1 receptor (IGF-1R)-mediated STAT3 activation specifically. Intracellular association of RACK1 via its N-terminal WD domains 1 to 4 (WD1-4) with insulin receptor (IR)/IGF-1R is augmented upon respective ligand stimulation, whereas association with STAT3 is constitutive. Purified RACK1 or RACK1 WD1-4 associates directly with purified IR, IGF-1R, and STAT3 in vitro. Insulin induces multiprotein complex formation of RACK1, IR, and STAT3. Overexpression or downregulation of RACK1 greatly enhances or decreases, respectively, IR/IGF-1R-mediated activation of STAT3 and its target gene expression. Site-specific mutants of IR and IGF-1R impaired in RACK1 binding are ineffective in mediating recruitment and activation of STAT3 as well as in insulin- or IGF-1-induced protection of cells from anoikis. RACK1-mediated STAT3 activation is important for insulin and IGF-1-induced anchorage-independent growth in certain ovarian cancer cells. We conclude that RACK1 mediates recruitment of STAT3 to IR and IGF-1R specifically for activation, suggesting a general paradigm for the need of an adaptor in mediating activation of STATs by receptor protein tyrosine kinases.
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Affiliation(s)
- Weizhou Zhang
- Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029-6574, USA
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14
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Ma FY, Anderson GM, Gunn TD, Goffin V, Grattan DR, Bunn SJ. Prolactin specifically activates signal transducer and activator of transcription 5b in neuroendocrine dopaminergic neurons. Endocrinology 2005; 146:5112-9. [PMID: 16123156 DOI: 10.1210/en.2005-0770] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The hypothalamic neuroendocrine dopaminergic (NEDA) neurons are crucial in regulating prolactin secretion from the anterior pituitary. Rising prolactin concentrations stimulate these neurons to secrete dopamine, which acts via the pituitary portal vasculature to inhibit additional prolactin release. Prolactin is known to activate Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathways in other cell types, including neurons. The possible role of JAK-STAT signaling in NEDA neurons has therefore been examined in this study using fetal rat mediobasal hypothalamic cell cultures and an adult rat in vivo preparation. Cultured cells expressing the dopamine synthesizing enzyme tyrosine hydroxylase (TH) responded to prolactin with a time-dependent increase in phospho-STAT5, but not phospho-STAT1 or phospho-STAT3, nuclear labeling. This response was inhibited by the prolactin receptor antagonist Delta1-9-G129R-human prolactin and the JAK inhibitor AG490, but was unaffected by selected serine/threonine kinase inhibitors (H89, KN-93, bisindolymaleimide, or PD98059). Antibodies selective for STAT5a or STAT5b indicated that the response was restricted to STAT5b, with the number of TH cells displaying STAT5b nuclear immunoreactivity rising from less than 10% under basal conditions to approximately 70% after prolactin stimulation. STAT5a nuclear labeling remained unchanged at 6-10% of TH-positive cells. STAT5b selectivity was confirmed in vivo, where the injection of prolactin into bromocriptine-treated rats stimulated a time-dependent increase in STAT5b, but not STAT5a, nuclear staining in the TH-expressing neurons in the arcuate nucleus. These results extend our previous findings with STAT5b-deficient mice and strongly suggest that in NEDA neurons, prolactin signaling via the JAK/STAT pathway is mediated exclusively by STAT5b.
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Affiliation(s)
- Frank Y Ma
- Center for Neuroendocrinology and Department of Anatomy and Structural Biology, University of Otago School of Medical Sciences, Dunedin, New Zealand
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15
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Klein M, Hempstead BL, Teng KK. Activation of STAT5-dependent transcription by the neurotrophin receptor Trk. ACTA ACUST UNITED AC 2005; 63:159-71. [PMID: 15702476 DOI: 10.1002/neu.20124] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Neurotrophins exert many of their biological effects via the Trk receptor tyrosine kinases and require the regulated activation of distinct transcriptional and post-translational cellular events. Here we provide evidence for a novel signaling cascade from activated Trks to the transcription factor STAT5. Utilizing the STAT5 responsive element derived from the p21(WAF1/Cip1) promoter to modulate luciferase expression, neurotrophin-dependent activation of Trk A, B, and C was found to induce STAT5-mediated transcriptional response. Structure-function analysis using Trk A mutants in heterologous cells further revealed that the kinase activity and an intact phospholipase C-gamma binding site are required for STAT5 activation. In most cytokine responsive cell systems, STAT5 function is modulated by JAK2-dependent tyrosine phosphorylation. However, reconstitution studies using a JAK2 deficient cell line indicate that neurotrophin-induced STAT5 activation does not require the cognate upstream kinase JAK2. In contrast, the Src kinase inhibitor PP1 significantly abolishes STAT5-dependent transcription in Trk A expressing 293T cells and in BDNF-treated primary cortical neurons. Together these results suggest that neurotrophins may regulate neuronal gene expression via STAT5 in a JAK2 independent manner.
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Affiliation(s)
- Mathias Klein
- Department of Medicine, Weill Medical College of Cornell University, New York, New York 10021, USA
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Plaza Menacho I, Koster R, van der Sloot AM, Quax WJ, Osinga J, van der Sluis T, Hollema H, Burzynski GM, Gimm O, Buys CHCM, Eggen BJL, Hofstra RMW. RET-familial medullary thyroid carcinoma mutants Y791F and S891A activate a Src/JAK/STAT3 pathway, independent of glial cell line-derived neurotrophic factor. Cancer Res 2005; 65:1729-37. [PMID: 15753368 DOI: 10.1158/0008-5472.can-04-2363] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The RET proto-oncogene encodes a receptor tyrosine kinase whose dysfunction plays a crucial role in the development of several neural crest disorders. Distinct activating RET mutations cause multiple endocrine neoplasia type 2A (MEN2A), type 2B (MEN2B), and familial medullary thyroid carcinoma (FMTC). Despite clear correlations between the mutations found in these cancer syndromes and their phenotypes, the molecular mechanisms connecting the mutated receptor to the different disease phenotypes are far from completely understood. Luciferase reporter assays in combination with immunoprecipitations, and Western and immunohistochemistry analyses were done in order to characterize the signaling properties of two FMTC-associated RET mutations, Y791F and S891A, respectively, both affecting the tyrosine kinase domain of the receptor. We show that these RET-FMTC mutants are monomeric receptors which are autophosphorylated and activated independently of glial cell line-derived neurotrophic factor. Moreover, we show that the dysfunctional signaling properties of these mutants, when compared with wild-type RET, involve constitutive activation of signal transducers and activators of transcription 3 (STAT3). Furthermore, we show that STAT3 activation is mediated by a signaling pathway involving Src, JAK1, and JAK2, differing from STAT3 activation promoted by RET(C634R) which was previously found to be independent of Src and JAKs. Three-dimensional modeling of the RET catalytic domain suggested that the structural changes promoted by the respective amino acids substitutions lead to a more accessible substrate and ATP-binding monomeric conformation. Finally, immunohistochemical analysis of FMTC tumor samples support the in vitro data, because nuclear localized, Y705-phosphorylated STAT3, as well as a high degree of RET expression at the plasma membrane was observed.
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Affiliation(s)
- Ivan Plaza Menacho
- Department of Medical Genetics, University of Groningen, Groningen, the Netherlands
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Nakagawa Y, Aoki N, Aoyama K, Shimizu H, Shimano H, Yamada N, Miyazaki H. Receptor-Type Protein Tyrosine Phosphatase ε (PTPεM) is a Negative Regulator of Insulin Signaling in Primary Hepatocytes and Liver. Zoolog Sci 2005; 22:169-75. [PMID: 15738637 DOI: 10.2108/zsj.22.169] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Impaired insulin receptor (IR) signaling leads to insulin resistance and type 2 diabetes mellitus. Several inhibitors of the IR tyrosine kinase activity have recently been described and associated with human insulin resistance. Among these negative regulators, protein tyrosine phosphatases (PTPs) are likely to play a pivotal role in IR signaling. Transgenic studies revealed that PTP1B and TCPTP are primary candidates but IR of these animals can be finally dephosphorylated, suggesting that other PTPs are also involved in the dephosphorylation of IR. In this study, we showed that receptor-type PTPepsilon (PTP epsilonM) dephosphorylated IR in rat primary hepatocytes and tyrosines 972, 1158, 1162 and 1163 were primary targets of PTP epsilonM. Wild type as well as substrate-trapping DA forms of PTPepsilonM suppressed phosphorylation of IR downstream enzymes such as Akt, extracellular regulated kinase (ERK) and glycogen synthase kinase 3 (GSK3). It was also demonstrated that PTPepsilonM suppressed insulin-induced glycogen synthesis and inhibited insulin-induced suppression of phosphoenol pyruvate carboxykinase (PEPCK) expression in primary hepatocytes. Furthermore, adenovirally introduced PTPepsilonM also exhibited inhibitory activity against suppression of PEPCK expression in mouse liver. These results suggest that PTPepsilonM is a negative regulator of IR signaling and involved in insulin-induced glucose metabolism mainly through direct dephosphorylation and inactivation of IR in hepatocytes and liver.
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