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Lee SK, Lee JO, Kim JH, Kim SJ, You GY, Moon JW, Jung JH, Park SH, Uhm KO, Park JM, Suh PG, Kim HS. Metformin sensitizes insulin signaling through AMPK-mediated pten down-regulation in preadipocyte 3T3-L1 cells. J Cell Biochem 2011; 112:1259-67. [DOI: 10.1002/jcb.23000] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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52
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Hao J, Zhu L, Zhao S, Liu S, Liu Q, Duan H. PTEN ameliorates high glucose-induced lipid deposits through regulating SREBP-1/FASN/ACC pathway in renal proximal tubular cells. Exp Cell Res 2011; 317:1629-39. [PMID: 21320485 DOI: 10.1016/j.yexcr.2011.02.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 02/07/2011] [Accepted: 02/08/2011] [Indexed: 12/31/2022]
Abstract
Phosphatase and tensin homology deleted on chromosome ten (PTEN) is a negative regulator of PI3K/Akt pathway, and here we investigated the effect of PTEN on lipogenesis in diabetic rats and high glucose-stimulated human renal proximal tubular cell line (HKC). Decreased PTEN and increased phospho-Akt were found in kidney of diabetic rats, and in vitro research revealed that high glucose attenuated PTEN expression in a time-dependent manner, concomitant with activation of Akt. Again, expression of PTEN significantly inhibited high glucose-caused increased phospho-Akt and lipogenic genes including SREBP-1, fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC). Furthermore, we confirmed inhibition of TGF-β1 pathway with SB431542 blocked the effect of high glucose on PTEN down-regulation, an increase in phospho-Akt and lipogenesis. These above data suggest that decreased PTEN mediates high glucose-induced lipogenesis in renal proximal tubular cells and TGF-β1 might be involved in PTEN down-regulation.
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Affiliation(s)
- Jun Hao
- Department of Pathology, Hebei Medical University, Shijiazhuang, China
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53
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Spry2 expression correlates with BRAF mutation in thyroid cancer. Surgery 2011; 148:1282-7; discussion 1287. [PMID: 21134562 DOI: 10.1016/j.surg.2010.09.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Accepted: 09/16/2010] [Indexed: 11/24/2022]
Abstract
BACKGROUND BRAF mutations activate the mitogen-activated protein kinase pathway and often confer an aggressive thyroid cancer (TC) phenotype. Spry2 is an inducible negative feedback regulator of the mitogen-activated protein kinase (MAPK) pathway. The aim of this study was to investigate the role of Spry2 in TC. METHODS TC cell lines were analyzed for Spry2 expression and MAPK pathway activation. Cells were treated with MEK inhibitor and Spry2 small hairpin RNA. Cells were analyzed for Spry2 expression and MEK/ERK phosphorylation (pMEK, pERK). Thirty human papillary TCs were analyzed for mitogen-activated protein kinase pathway activating mutations and Spry2 expression. RESULTS Increased baseline pMEK levels and Spry2 expression was found in BRAF V600E mutant (BRAF+) cells. MEK inhibition in BRAF+ cells showed decreased Spry2 expression and decreased pMEK/pERK levels. From our tissue samples, 10 papillary TCs had BRAF mutation, and increased Spry2 expression was found only in BRAF+ tumors. CONCLUSION Spry2 expression correlates with BRAF status in vitro and in human tissue. Spry2 may serve as a negative feedback regulator of the mitogen-activated protein kinase pathway in BRAF+ TC. Increased Spry2 expression may serve as a surrogate marker of mitogen-activated protein kinase pathway activation with prognostic and therapeutic implications.
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Abstract
The phosphoinositide 3-kinase (PI3K)/phosphatase and tensin homolog (PTEN)/Akt axis is a key signal transduction node that regulates crucial cellular functions, including insulin and other growth factors signaling, lipid and glucose metabolism, as well as cell survival and apoptosis. In this pathway, PTEN acts as a phosphoinositide phosphatase, which terminates PI3K-propagated signaling by dephosphorylating PtdIns(3,4)P2 and PtdIns(3,4,5)P3. However, the role of PTEN does not appear to be restricted only to PI3K signaling antagonism, and new functions have been recently discovered for this protein. In addition to the well-established role of PTEN as a tumor suppressor, increasing evidence now suggests that a dysregulated PTEN expression and/or activity is also linked to the development of several hepatic pathologies. Dysregulated PTEN expression/activity is observed with obesity, insulin resistance, diabetes, hepatitis B virus/hepatitis C virus infections, and abusive alcohol consumption, whereas mutations/deletions have also been associated with the occurrence of hepatocellular carcinoma. Thus, it appears that alterations of PTEN expression and activity in hepatocytes are common and recurrent molecular events associated with liver disorders of various etiologies. These recent findings suggest that PTEN might represent a potential common therapeutic target for a number of liver pathologies.
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Mayer CE, Haigl B, Jantscher F, Siegwart G, Grusch M, Berger W, Sutterlüty H. Bimodal expression of Sprouty2 during the cell cycle is mediated by phase-specific Ras/MAPK and c-Cbl activities. Cell Mol Life Sci 2010; 67:3299-311. [PMID: 20461437 PMCID: PMC11115549 DOI: 10.1007/s00018-010-0379-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 04/14/2010] [Accepted: 04/20/2010] [Indexed: 10/19/2022]
Abstract
Sprouty2 is an important inhibitor of cell proliferation and signal transduction. In this study, we found a bimodal expression of Sprouty2 protein during cell cycle progression after exit from quiescence, whereas elevated Sprouty4 expression in the G1 phase stayed high throughout the rest of the cell cycle. Induction of the mitogen-activated protein kinase via activated Ras was crucial for increased Sprouty2 expression at the G0/G1 transition. Following the first peak, accelerated proteasomal protein degradation caused a transient attenuation of Sprouty2 abundance during late G1. Since the decline in its expression was abolished by dominant negative c-Cbl and the timely restricted interaction between Sprouty2 and c-Cbl disappeared at the second peak of Sprouty2 expression, we conclude that the second phase in the cell cycle-specific expression profile of Sprouty2 is solely dependent on ubiquitination by c-Cbl. Our results suggest that Sprouty2 abundance is the result of strictly coordinated activities of Ras and c-Cbl.
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Affiliation(s)
- Christoph-Erik Mayer
- Department of Medicine I, Institute of Cancer Research, Medical University of Vienna, Borschkegasse 8a, 1090 Vienna, Austria.
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Feng YH, Tsao CJ, Wu CL, Chang JG, Lu PJ, Yeh KT, Shieh GS, Shiau AL, Lee JC. Sprouty2 protein enhances the response to gefitinib through epidermal growth factor receptor in colon cancer cells. Cancer Sci 2010; 101:2033-8. [PMID: 20624167 PMCID: PMC11159513 DOI: 10.1111/j.1349-7006.2010.01637.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Sprouty2 (Spry2) is known to increase the expression of epidermal growth factor receptors (EGFR) by conjugating with c-Casitas B-lineage lymphoma (C-Cbl) to decrease protein degradation. The effect of Spry2 on the treatment of gefitinib, a tyrosine kinase inhibitor of EGFR, with regards to colon cancer is still unclear. The half maximal inhibitory concentration (IC50) values of gefitinib in six colon cancer cell lines were assessed. HCT116 and C2BBel cells expressed lower levels of Spry2 protein and were less sensitive to gefitinib, whereas HT29 cells that expressed high levels of Spry2 protein were more sensitive to gefitinib. The sensitivity to gefitinib was increased after overexpression of Spry2 in HCT116 cells, whereas it was decreased after Spry2 knockdown in HT29 cells. The levels of both phosphorylated and total EGFR were increased when HCT116 cells ectopically overexpressed Spry2, with concomitant increase in phosphatase and tensin homolog (PTEN) expression. Inhibition of EGFR by cetuximab reduced sensitivity to gefitinib in HCT116 cells overexpressing Spry2. However, knockdown of PTEN or K-ras failed to diminish the effect of Spry2 on gefitinib sensitivity. Of note, Spry2 enhanced the antitumor effect of gefitinib in a xenograft model of HCT116 tumors, which harbored K-ras codon 13 mutation. In conclusion, Spry2 can enhance the response of colon cancer cells to gefitinib by increasing the expression of phosphorylated and total EGFR. These results suggest that Spry2 may be a potential biomarker in predicting the response to anti-EGFR treatment in colon cancer and that it is necessary to conduct clinical studies to incorporate Spry2 into the network of cancer treatment.
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Affiliation(s)
- Yin-Hsun Feng
- Graduate Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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57
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Assidi M, Dieleman SJ, Sirard MA. Cumulus cell gene expression following the LH surge in bovine preovulatory follicles: potential early markers of oocyte competence. Reproduction 2010; 140:835-52. [PMID: 20724459 DOI: 10.1530/rep-10-0248] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cumulus cells (CCs) are essential for oocytes to reach full development competency and become fertilized. Many major functional properties of CCs are triggered by gonadotropins and governed by the oocyte. Consequently, cumulus may reflect oocyte quality and is often used for oocyte selection. The most visible function of CCs is their ability for rapid extracellular matrix expansion after the LH surge. Although unexplained, LH induces the final maturation and improves oocyte quality. To study the LH signaling and gene expression cascade patterns close to the germinal vesicle breakdown, bovine CCs collected at 2 h before and 6 h after the LH surge were hybridized to a custom-made microarray to better understand the LH genomic action and find differentially expressed genes associated with the LH-induced oocyte final maturation. Functional genomic analysis of the 141 overexpressed and 161 underexpressed clones was performed according to their molecular functions, gene networks, and cell compartments. Following real-time PCR validation of our gene lists, some interesting pathways associated with the LH genomic action on CCs and their possible roles in oocyte final maturation, ovulation, and fertilization are discussed. A list of early potential markers of oocyte competency in vivo and in vitro is thereafter suggested. These early biomarkers are a preamble to understand the LH molecular pathways that trigger the final oocyte competence acquisition process in bovine.
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Affiliation(s)
- Mourad Assidi
- Centre de Recherche en Biologie de la Reproduction, Université Laval, Québec, Québec, G1K 7P4, Canada
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58
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Holgren C, Dougherty U, Edwin F, Cerasi D, Taylor I, Fichera A, Joseph L, Bissonnette M, Khare S. Sprouty-2 controls c-Met expression and metastatic potential of colon cancer cells: sprouty/c-Met upregulation in human colonic adenocarcinomas. Oncogene 2010; 29:5241-53. [PMID: 20661223 PMCID: PMC2945447 DOI: 10.1038/onc.2010.264] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Sprouty negatively regulates receptor tyrosine kinase signals by inhibiting Ras/ERK pathways. Sprouty is down-regulated in breast, prostate and liver cancers and appears to function as a tumor suppressor. The role of Sprouty in colonic neoplasia, however, has not been investigated. Sprouty-2 protein and mRNA transcripts were significantly up-regulated in human colonic adenocarcinomas. Strikingly, the c-Met receptor was also upregulated in tumors with increased sprouty-2. To delineate a potential causal relationship between sprouty-2 and c-Met, K-ras mutant HCT-116 colon cancer cells were transduced with purified TAT-sprouty-2 protein or stably transfected with full-length human sprouty-2 gene. Sprouty-2 up-regulation significantly increased cell proliferation by accelerating cell cycle transition. Sprouty-2 transfectants demonstrated strong up-regulation of c-Met protein and mRNA transcripts and hepatocyte growth factor stimulated ERK and Akt phosphorylation and enhanced cell migration and invasion. In contrast, knockdown of c-Met by siRNA significantly decreased cell proliferation, migration and invasion in sprouty-2 transfectants. Further, knockdown of sprouty-2 by siRNA in parental HT-29 and LS-174T colon cancer cells also decreased cell invasion. Sprouty-2 transfectants formed significantly larger tumor xenografts and demonstrated increased proliferation and angiogenesis and suppressed apoptosis. Sprouty-2 tumors metastasized to liver from cecal orthotopic implants suggesting sprouty-2 might also enhance metastatic signals. Thus in colon cancer sprouty functions as an oncogene and its effects are mediated in part by c-Met up-regulation.
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Affiliation(s)
- C Holgren
- Hines Veterans Affairs Medical Center, Hines, IL, USA
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59
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Csóka B, Németh ZH, Rosenberger P, Eltzschig HK, Spolarics Z, Pacher P, Selmeczy Z, Koscsó B, Himer L, Vizi ES, Blackburn MR, Deitch EA, Haskó G. A2B adenosine receptors protect against sepsis-induced mortality by dampening excessive inflammation. THE JOURNAL OF IMMUNOLOGY 2010; 185:542-50. [PMID: 20505145 DOI: 10.4049/jimmunol.0901295] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Despite intensive research, efforts to reduce the mortality of septic patients have failed. Adenosine is a potent extracellular signaling molecule, and its levels are elevated in sepsis. Adenosine signals through G-protein-coupled receptors and can regulate the host's response to sepsis. In this study, we studied the role of A(2B) adenosine receptors in regulating the mortality and inflammatory response of mice following polymicrobial sepsis. Genetic deficiency of A(2B) receptors increased the mortality of mice suffering from cecal ligation and puncture-induced sepsis. The increased mortality of A(2B) knockout mice was associated with increased levels of inflammatory cytokines and chemokines and augmented NF-kappaB and p38 activation in the spleen, heart, and plasma in comparison with wild-type animals. In addition, A(2B) receptor knockout mice showed increased splenic apoptosis and phosphatase and tensin homolog activation and decreased Akt activation. Experiments using bone-marrow chimeras revealed that it is the lack of A(2B) receptors on nonhematopoietic cells that is primarily responsible for the increased inflammation of septic A(2B) receptor-deficient mice. These results indicate that A(2B) receptor activation may offer a new therapeutic approach for the management of sepsis.
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Affiliation(s)
- Balázs Csóka
- Department of Surgery, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103, USA
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60
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Establishment of extracellular signal-regulated kinase 1/2 bistability and sustained activation through Sprouty 2 and its relevance for epithelial function. Mol Cell Biol 2010; 30:1783-99. [PMID: 20123980 DOI: 10.1128/mcb.01003-09] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Our objective was to establish an experimental model of a self-sustained and bistable extracellular signal-regulated kinase 1/2 (ERK1/2) signaling process. A single stimulation of cells with cytokines causes rapid ERK1/2 activation, which returns to baseline in 4 h. Repeated stimulation leads to sustained activation of ERK1/2 but not Jun N-terminal protein kinase (JNK), p38, or STAT6. The ERK1/2 activation lasts for 3 to 7 days and depends upon a positive-feedback mechanism involving Sprouty 2. Overexpression of Sprouty 2 induces, and its genetic deletion abrogates, ERK1/2 bistability. Sprouty 2 directly activates Fyn kinase, which then induces ERK1/2 activation. A genome-wide microarray analysis shows that the bistable phospho-ERK1/2 (pERK1/2) does not induce a high level of gene transcription. This is due to its nuclear exclusion and compartmentalization to Rab5+ endosomes. Cells with sustained endosomal pERK1/2 manifest resistance against growth factor withdrawal-induced cell death. They are primed for heightened cytokine production. Epithelial cells from cases of human asthma and from a mouse model of chronic asthma manifest increased pERK1/2, which is associated with Rab5+ endosomes. The increase in pERK1/2 was associated with a simultaneous increase in Sprouty 2 expression in these tissues. Thus, we have developed a cellular model of sustained ERK1/2 activation, which may provide a mechanistic understanding of self-sustained biological processes in chronic illnesses such as asthma.
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61
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Edwin F, Anderson K, Patel TB. HECT domain-containing E3 ubiquitin ligase Nedd4 interacts with and ubiquitinates Sprouty2. J Biol Chem 2009; 285:255-64. [PMID: 19864419 DOI: 10.1074/jbc.m109.030882] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Sprouty (Spry) proteins are important regulators of receptor tyrosine kinase signaling in development and disease. Alterations in cellular Spry content have been associated with certain forms of cancers and also in cardiovascular diseases. Thus, understanding the mechanisms that regulate cellular Spry levels are important. Herein, we demonstrate that Spry1 and Spry2, but not Spry3 or Spry4, associate with the HECT domain family E3 ubiquitin ligase, Nedd4. The Spry2/Nedd4 association involves the WW domains of Nedd4 and requires phosphorylation of the Mnk2 kinase sites, Ser(112) and Ser(121), on Spry2. The phospho-Ser(112/121) region on Spry2 that binds WW domains of Nedd4 is a novel non-canonical WW domain binding region that does not contain Pro residues after phospho-Ser. Endogenous and overexpressed Nedd4 polyubiquitinate Spry2 via Lys(48) on ubiquitin and decrease its stability. Silencing of endogenous Nedd4 increased the cellular Spry2 content and attenuated fibroblast growth factor-elicited ERK1/2 activation that was reversed when elevations in Spry2 levels were prevented by Spry2-specific small interfering RNA. Mnk2 silencing decreased Spry2-Nedd4 interactions and also augmented the ability of Spry2 to inhibit fibroblast growth factor signaling. This is the first report demonstrating the regulation of cellular Spry content and its ability to modulate receptor tyrosine kinase signaling by a HECT domain-containing E3 ubiquitin ligase.
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Affiliation(s)
- Francis Edwin
- Department of Pharmacology and Experimental Therapeutics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois 60153, USA
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62
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Abstract
Small non-coding miRNAs (microRNAs) are emerging as key factors involved in cancer at all stages ranging from initiation to metastasis. MIRN21 is an miRNA gene that codes for the miR-21 miRNA which has been found to be overexpressed in many tumour samples where it has been analysed. Whereas consistent overexpression of miR-21 in tumours could be suggestive of functional effects of miR-21 in cancer, more in-depth functional studies with miR-21 are demonstrating that mir-21 displays oncogenic activity and can be classed as an oncomir. Extensive efforts are underway to identify the downstream genes and gene networks regulated by miR-21 and to identify the upstream factors that are regulating expression of miR-21. Even though miR-21 is one of the most intensively studied miRNAs, for all miRNAs, our understanding of miRNA signalling pathways is currently in its early stages. The unravelling of such RNA signalling pathways and networks will be key to understanding the role that dysregulated miRNA functioning can play in oncogenic processes.
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63
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Brady SC, Coleman ML, Munro J, Feller SM, Morrice NA, Olson MF. Sprouty2 association with B-Raf is regulated by phosphorylation and kinase conformation. Cancer Res 2009; 69:6773-81. [PMID: 19690147 DOI: 10.1158/0008-5472.can-08-4447] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sprouty2 is a feedback regulator that controls the Ras/Raf/MEK/extracellular signal-regulated kinase mitogen-activated protein kinase (MAPK) pathway at multiple levels, one way being through direct interaction with Raf kinases. Consistent with a role as a tumor suppressor, Sprouty2 expression is often down-regulated in human cancers. However, Sprouty2 is up-regulated in some cancers, suggesting the existence of posttranscriptional mechanisms that permit evasion of Sprouty2-mediated antitumorigenic properties. We report that MAPK activation induces Sprouty2 phosphorylation on six serine residues, which reduced Sprouty2 association with wild-type B-Raf. Mutation of these six serines to nonphosphorylatable alanines increased the ability of Sprouty2 to inhibit growth factor-induced MAPK activation. Oncogenic B-Raf mutants such as B-Raf V600E did not associate with Sprouty2, but this resistance to Sprouty2 binding was not due to phosphorylation. Instead, the active kinase conformation induced by oncogenic mutation prevents Sprouty2 binding. These results reveal a dual mechanism that affects the Sprouty2/B-Raf interaction: Sprouty phosphorylation and B-Raf conformation.
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Affiliation(s)
- Suzanne C Brady
- The Beatson Institute for Cancer Research, Glasgow, United Kingdom
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64
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Edwin F, Anderson K, Ying C, Patel TB. Intermolecular interactions of Sprouty proteins and their implications in development and disease. Mol Pharmacol 2009; 76:679-91. [PMID: 19570949 DOI: 10.1124/mol.109.055848] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Receptor tyrosine kinase (RTK) signaling is spatially and temporally regulated by a number of positive and negative regulatory mechanisms. These regulatory mechanisms control the amplitude and duration of the signals initiated at the cell surface to have a normal or aberrant biological outcome in development and disease, respectively. In the past decade, the Sprouty (Spry) family of proteins has been identified as modulators of RTK signaling in normal development and disease. This review summarizes recent advances concerning the biological activities modulated by Spry family proteins, their interactions with signaling proteins, and their involvement in cardiovascular diseases and cancer. The diversity of mechanisms in the regulation of Spry expression and activity in cell systems emphasizes the crucial role of Spry proteins in development and growth across the animal kingdom.
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Affiliation(s)
- Francis Edwin
- Department of Pharmacology and Experimental Therapeutics, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
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65
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Liu YL, Castleberry RP, Emanuel PD. PTEN deficiency is a common defect in juvenile myelomonocytic leukemia. Leuk Res 2008; 33:671-7. [PMID: 19010541 DOI: 10.1016/j.leukres.2008.09.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Revised: 09/23/2008] [Accepted: 09/24/2008] [Indexed: 10/21/2022]
Abstract
The biological hallmark of juvenile myelomonocytic leukemia (JMML) is selective GM-CSF hypersensitivity. We hypothesized that PTEN protein deficiency might lead to insufficient negative growth signals to counter the hyperactive Ras signaling and therefore aid in the acceleration of the malignant transformation of JMML. In screening 34 JMML patients we found: (1) decreased PTEN protein in 67% of patients; (2) significantly lower PTEN mRNA levels in patients compared to controls (p<0.01); (3) a hypermethylated PTEN promoter in 77% of patients; and (4) constitutive-hyperactive Akt and MAPK in 55% and 73% of patients, respectively. These findings suggest that PTEN deficiency is very common in JMML and is in part due to hypermethylation of the PTEN gene promoter.
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Affiliation(s)
- Yunying Lucy Liu
- Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, 4301 West Markham Street, slot #623, Little Rock, AR 72205-7199, USA
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66
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Lito P, Mets BD, Appledorn DM, Maher VM, McCormick JJ. Sprouty 2 regulates DNA damage-induced apoptosis in Ras-transformed human fibroblasts. J Biol Chem 2008; 284:848-54. [PMID: 19008219 DOI: 10.1074/jbc.m808045200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have reported that expression of Sprouty 2 (Spry2) is necessary for tumor formation by HRas(V12)-transformed fibroblasts. We now report on the role of Spry2 in the inhibition of UV(254 nm) radiation-induced apoptosis in HRas(V12)-transformed human fibroblasts. Silencing Spry2 in this context resulted in increased apoptosis, associated with decreased Akt activation and decreased phosphorylation of HDM2 at Ser-166, which has been shown to stabilize HDM2. As a consequence, when cells with silenced Spry2 were UV-irradiated, they exhibited diminished levels of HDM2 and elevated levels of p53. In agreement with these findings, overexpression of Spry2 in the parental non-transformed fibroblasts led to increased Akt activation and to the stabilization of HDM2. It also led to diminished expression of p53 and decreased apoptosis following UV irradiation. Silencing Spry2 in HRas-transformed cells decreased Rac1 activation, but independent expression of Spry2 in the non-transformed parental cells had no effect on Rac1, suggesting a specific involvement in the activation of Rac1 by Ras. Silencing Spry2 in HRas(V12)-transformed cells resulted in diminished interaction between HRas and Tiam1, a Rac1-specific nucleotide exchange factor. Expression of constitutively active Rac1 in cells with silenced Spry2 partly reversed the effect of Spry2 down-regulation. Furthermore, loss of Spry2 expression in HRas(V12)-transformed cells augmented the cytotoxicity of the DNA-damaging, chemotherapeutic agent cisplatin, a process that was also reversed by active Rac1. Together, these data show that Spry2 inhibits apoptosis in response to DNA damage by regulating Akt, HDM2, and p53, by a process mediated partly by Rac1.
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Affiliation(s)
- Piro Lito
- Carcinogenesis Laboratory, Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-1302, USA
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67
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High miR-21 expression in breast cancer associated with poor disease-free survival in early stage disease and high TGF-beta1. Breast Cancer Res Treat 2008; 117:131-40. [PMID: 18932017 DOI: 10.1007/s10549-008-0219-7] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 10/01/2008] [Indexed: 01/02/2023]
Abstract
MicroRNA-21 (miR-21) is considered an onco-microRNA given its abilities to suppress the actions of several tumor suppressor genes and to promote tumor cell growth, invasion and metastasis. Recently, transforming growth factor-beta (TGF-beta) is found to up-regulate the expression of miR-21, and elevated miR-21 expression is seen frequently in breast cancer. To evaluate the effect of miR-21 on disease progression and its association with TGF-beta, we analyzed miR-21 expression in breast cancer. Fresh tumor samples were collected during surgery from 344 patients diagnosed with primary breast cancer. The expression of miR-21 in tumor samples was measured with a TaqMan microRNA assay using U6 as reference. Levels of miR-21 expression by disease stage, tumor grade, histology, hormone receptor status and lymph node involvement were compared. Cox proportional hazards regression analysis was performed to assess the association of miR-21 expression with disease-free and overall survival. The study results showed that the expression of miR-21 was detected in all tumor samples with substantial variation. High miR-21 expression was associated with features of aggressive disease, including high tumor grade, negative hormone receptor status, and ductal carcinoma. High miR-21 was also positively correlated with TGF-beta1. No associations were found between patient survival and miR-21 expression among all patients, but high miR-21 was associated with poor disease-free survival in early stage patients (HR = 2.08, 95% CI: 1.08-4.00) despite no value for prognosis. The study supports the notion that miR-21 is an onco-microRNA for breast cancer. Elevated miR-21 expression may facilitate tumor progression, and TGF-beta may up-regulate its expression.
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Down-regulation of Sprouty2 via p38 MAPK plays a key role in the induction of cellular apoptosis by tumor necrosis factor-alpha. Biochem Biophys Res Commun 2008; 375:460-4. [PMID: 18713620 DOI: 10.1016/j.bbrc.2008.08.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Accepted: 08/12/2008] [Indexed: 02/05/2023]
Abstract
Mammalian Sprouty2 (Spry2) is a key regulator of the receptor tyrosine kinase/ERK signaling pathway and involved in many biological processes, including cell growth, migration, and tumor suppression. Here, we demonstrated that the intracellular protein level of Spry2 was significantly down-regulated by tumor necrosis factor-alpha (TNF-alpha) in both murine Swiss 3T3 fibroblasts and MLE15 lung epithelial cells. Although TNF-alpha activates multiple signaling cascades, only the inhibitor of p38 MAPK pathway blocked TNF-alpha-induced Spry2 down-regulation. Moreover, since both the mRNA level and protein half-life of Spry2 were unaltered by TNF-alpha treatment, this indicated the possible involvement of a translational mechanism in mediating the inhibitory effect of TNF-alpha. Importantly, rescue of the TNF-alpha-induced down-regulation of Spry2 by gene overexpression led to reverse of the apoptotic effect of TNF-alpha in Swiss 3T3 cells. To our knowledge, this study is the first that reported the association of Spry2 with TNF-alpha signaling pathway.
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Sayed D, Rane S, Lypowy J, He M, Chen IY, Vashistha H, Yan L, Malhotra A, Vatner D, Abdellatif M. MicroRNA-21 targets Sprouty2 and promotes cellular outgrowths. Mol Biol Cell 2008; 19:3272-82. [PMID: 18508928 PMCID: PMC2488276 DOI: 10.1091/mbc.e08-02-0159] [Citation(s) in RCA: 281] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The posttranscriptional regulator, microRNA-21 (miR-21), is up-regulated in many forms of cancer, as well as during cardiac hypertrophic growth. To understand its role, we overexpressed it in cardiocytes where it revealed a unique type of cell-to-cell "linker" in the form of long slender outgrowths and branches. We subsequently confirmed that miR-21 directly targets and down-regulates the expression of Sprouty2 (SPRY2), an inhibitor of branching morphogenesis and neurite outgrowths. We found that beta-adrenergic receptor (betaAR) stimulation induces up-regulation of miR-21 and down-regulation of SPRY2 and is, likewise, associated with connecting cell branches. Knockdown of SPRY2 reproduced the branching morphology in cardiocytes, and vice versa, knockdown of miR-21 using a specific 'miRNA eraser' or overexpression of SPRY2 inhibited betaAR-induced cellular outgrowths. These structures enclose sarcomeres and connect adjacent cardiocytes through functional gap junctions. To determine how this aspect of miR-21 function translates in cancer cells, we knocked it down in colon cancer SW480 cells. This resulted in disappearance of their microvillus-like protrusions accompanied by SPRY2-dependent inhibition of cell migration. Thus, we propose that an increase in miR-21 enhances the formation of various types of cellular protrusions through directly targeting and down-regulating SPRY2.
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Affiliation(s)
- Danish Sayed
- Cardiovascular Research Institute, Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA
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70
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Chugh P, Bradel-Tretheway B, Monteiro-Filho CMR, Planelles V, Maggirwar SB, Dewhurst S, Kim B. Akt inhibitors as an HIV-1 infected macrophage-specific anti-viral therapy. Retrovirology 2008; 5:11. [PMID: 18237430 PMCID: PMC2265748 DOI: 10.1186/1742-4690-5-11] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Accepted: 01/31/2008] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Unlike CD4+ T cells, HIV-1 infected macrophages exhibit extended life span even upon stress, consistent with their in vivo role as long-lived HIV-1 reservoirs. RESULTS Here, we demonstrate that PI3K/Akt inhibitors, including clinically available Miltefosine, dramatically reduced HIV-1 production from long-living virus-infected macrophages. These PI3K/Akt inhibitors hyper-sensitize infected macrophages to extracellular stresses that they are normally exposed to, and eventually lead to cell death of infected macrophages without harming uninfected cells. Based on the data from these Akt inhibitors, we were able to further investigate how HIV-1 infection utilizes the PI3K/Akt pathway to establish the cytoprotective effect of HIV-1 infection, which extends the lifespan of infected macrophages, a key viral reservoir. First, we found that HIV-1 infection activates the well characterized pro-survival PI3K/Akt pathway in primary human macrophages, as reflected by decreased PTEN protein expression and increased Akt kinase activity. Interestingly, the expression of HIV-1 or SIV Tat is sufficient to mediate this cytoprotective effect, which is dependent on the basic domain of Tat - a region that has previously been shown to bind p53. Next, we observed that this interaction appears to contribute to the downregulation of PTEN expression, since HIV-1 Tat was found to compete with PTEN for p53 binding; this is known to result in p53 destabilization, with a consequent reduction in PTEN protein production. CONCLUSION Since HIV-1 infected macrophages display highly elevated Akt activity, our results collectively show that PI3K/Akt inhibitors may be a novel therapy for interfering with the establishment of long-living HIV-1 infected reservoirs.
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Affiliation(s)
- Pauline Chugh
- Department of Microbiology and Immunology, School of Medicine, University of Rochester Medical Center 601 Elmwood Avenue Box 672 Rochester, New York 14742 USA.
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71
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Toyoshima F, Matsumura S, Morimoto H, Mitsushima M, Nishida E. PtdIns(3,4,5)P3 regulates spindle orientation in adherent cells. Dev Cell 2008; 13:796-811. [PMID: 18061563 DOI: 10.1016/j.devcel.2007.10.014] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Revised: 08/30/2007] [Accepted: 10/24/2007] [Indexed: 12/21/2022]
Abstract
Cultured adherent cells divide on the substratum, leading to formation of the cell monolayer. However, how the orientation of this anchorage-dependent cell division is regulated remains unknown. We have previously shown that integrin-dependent adhesion orients the spindle parallel to the substratum, which ensures this anchorage-dependent cell division. Here, we show that phosphatidylinositol-3,4,5-triphosphate (PtdIns(3,4,5)P3) is essential for this spindle orientation control. In metaphase, PtdIns(3,4,5)P3 is accumulated in the midcortex in an integrin-dependent manner. Inhibition of phosphatidylinositol-3-OH kinase (PI(3)K) reduces the accumulation of PtdIns(3,4,5)P3 and induces spindle misorientation. Introduction of PtdIns(3,4,5)P3 to these cells restores the midcortical accumulation of PtdIns(3,4,5)P3 and proper spindle orientation. PI(3)K inhibition causes dynein-dependent spindle rotations along the z-axis, resulting in spindle misorientation. Moreover, dynactin, a dynein-binding partner, is accumulated in the midcortex in a PtdIns(3,4,5)P3-dependent manner. We propose that PtdIns(3,4,5)P3 directs dynein/dynactin-dependent pulling forces on spindles to the midcortex, and thereby orients the spindle parallel to the substratum.
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Affiliation(s)
- Fumiko Toyoshima
- Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
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72
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Edwin F, Patel TB. A novel role of Sprouty 2 in regulating cellular apoptosis. J Biol Chem 2007; 283:3181-3190. [PMID: 18070883 DOI: 10.1074/jbc.m706567200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sprouty (SPRY) proteins modulate receptor-tyrosine kinase signaling and, thereby, regulate cell migration and proliferation. Here, we have examined the role of endogenous human SPRY2 (hSPRY2) in the regulation of cellular apoptosis. Small inhibitory RNA-mediated silencing of hSPRY2 abolished the anti-apoptotic action of serum in adrenal cortex adenocarcinoma (SW13) cells. Silencing of hSPRY2 decreased serum- or epidermal growth factor (EGF)-elicited activation of AKT and ERK1/2 and reduced the levels of EGF receptor. Silencing of hSPRY2 also inhibited serum-induced activation of p90RSK and decreased phosphorylation of pro-apoptotic protein BAD (BCL2-antagonist of cell death) by p90RSK. Inhibiting both the ERK1/2 and AKT pathways abolished the ability of serum to protect against apoptosis, mimicking the effects of silencing hSPRY2. Serum transactivated the EGF receptor (EGFR), and inhibition of the EGFR by a neutralizing antibody attenuated the anti-apoptotic actions of serum. Consistent with the role of EGFR and perhaps other growth factor receptors in the anti-apoptotic actions of serum, the tyrosine kinase binding domain of c-Cbl (Cbl-TKB) protected against down-regulation of the growth factor receptors such as EGFR and preserved the anti-apoptotic actions of serum when hSpry2 was silenced. Additionally, silencing of Spry2 in c-Cbl null cells did not alter the ability of serum to promote cell survival. Moreover, reintroduction of wild type hSPRY2, but not its mutants that do not bind c-Cbl or CIN85 into SW13 cells after endogenous hSPRY2 had been silenced, restored the anti-apoptotic actions of serum. Overall, we conclude that endogenous hSPRY2-mediated regulation of apoptosis requires c-Cbl and is manifested by the ability of hSPRY2 to sequester c-Cbl and thereby augment signaling via growth factor receptors.
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Affiliation(s)
- Francis Edwin
- Department of Pharmacology and Experimental Therapeutics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois 60153
| | - Tarun B Patel
- Department of Pharmacology and Experimental Therapeutics, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois 60153.
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Abstract
The functions ascribed to PTEN have become more diverse since its discovery as a putative phosphatase mutated in many human tumors. Although it can dephosphorylate lipids and proteins, it also has functions independent of phosphatase activity in normal and pathological states. In addition, control of PTEN function is very complex. It is positively and negatively regulated at the transcriptional level, as well as post-translationally by phosphorylation, ubiquitylation, oxidation and acetylation. Although most of its tumor suppressor activity is likely to be caused by lipid dephosphorylation at the plasma membrane, PTEN also resides in the cytoplasm and nucleus, and its subcellular distribution is under strict control. Deregulation of PTEN function is implicated in other human diseases in addition to cancer, including diabetes and autism.
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Affiliation(s)
- Tanja Tamguney
- UCSF Cancer Research Institute, 2340 Sutter Street, San Francisco, CA 94115, USA
| | - David Stokoe
- UCSF Cancer Research Institute, 2340 Sutter Street, San Francisco, CA 94115, USA
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74
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Chandramouli S, Yu CY, Yusoff P, Lao DH, Leong HF, Mizuno K, Guy GR. Tesk1 interacts with Spry2 to abrogate its inhibition of ERK phosphorylation downstream of receptor tyrosine kinase signaling. J Biol Chem 2007; 283:1679-1691. [PMID: 17974561 DOI: 10.1074/jbc.m705457200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Sprouty (Spry) proteins function as inhibitors of the Ras-ERK pathway downstream of various receptor tyrosine kinases. In this study, we have identified Tesk1 (testicular protein kinase 1) as a novel regulator of Spry2 function. Endogenous Tesk1 and Spry2 exist in a complex in cell lines and mouse tissues. Tesk1 coexpression relocalizes Spry2 to vesicles including endosomes, inhibiting its translocation to membrane ruffles upon growth factor stimulation. Independent of its kinase activity, Tesk1 binding leads to a loss of Spry2 function as an inhibitor of ERK phosphorylation and reverses inhibition of basic fibroblast growth factor (bFGF)- and nerve growth factor-induced neurite outgrowth in PC12 cells by Spry2. Furthermore, depletion of endogenous Tesk1 in PC12 cells leads to a reduction in neurite outgrowth induced by bFGF. Tesk1 nullifies the inhibitory effect of Spry2 by abrogating its interaction with the adaptor protein Grb2 and interfering with its serine dephosphorylation upon bFGF and FGF receptor 1 stimulation by impeding its binding to the catalytic subunit of protein phosphatase 2A. A construct of Tesk1 that binds to Spry2 but does not localize to the vesicles does not interfere with its function, highlighting the importance of subcellular localization of Tesk1 in this context. Conversely, Tesk1 does not affect interaction of Spry2 with the E3 ubiquitin ligase, c-Cbl, and consequently, does not affect its inhibition of Cbl-mediated ubiquitination of the epidermal growth factor receptor. By selectively modulating the downstream effects of Spry2, Tesk1 may thus serve as a molecular determinant of the signaling outcome.
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Affiliation(s)
- Sumana Chandramouli
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673
| | - Chye Yun Yu
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673
| | - Permeen Yusoff
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673
| | - Dieu-Hung Lao
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673
| | - Hwei Fen Leong
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673
| | - Kensaku Mizuno
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Graeme R Guy
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673.
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Ongür D, Pohlman J, Dow AL, Eisch AJ, Edwin F, Heckers S, Cohen BM, Patel TB, Carlezon WA. Electroconvulsive seizures stimulate glial proliferation and reduce expression of Sprouty2 within the prefrontal cortex of rats. Biol Psychiatry 2007; 62:505-12. [PMID: 17336937 DOI: 10.1016/j.biopsych.2006.11.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 11/14/2006] [Accepted: 11/17/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND Reductions in cell number are found within the medial prefrontal cortex (PFC) in major depression and bipolar disorder, conditions for which electroconvulsive therapy (ECT) is a highly effective treatment. We investigated whether electroconvulsive seizure (ECS) in rats stimulates cellular proliferation in the PFC immediately and four weeks after the treatments. In parallel, we examined if ECS also alters the expression of Sprouty2 (SPRY2), an inhibitor of cell proliferation. METHODS Sprague-Dawley rats received 10 days of ECS treatments and bromodeoxyuridine (BrdU) injections. After a four week survival period, we estimated the density and number of BrdU-, proliferating cell nuclear antigen (PCNA)-, and SPRY2-immunoreactive cells in the medial (infralimbic) PFC (ILPFC). We also determined the percentage of BrdU-labeled cells that were immunoreactive for markers specific to oligodendrocytes, astrocytes, endothelial cells and neurons. RESULTS ECS dramatically enhanced the proliferation of new cells in the infralimbic PFC, and this effect persisted four weeks following the treatments. The percentage of new cells expressing oligodendrocyte precursor cell markers increased slightly following ECS. In contrast, ECS dramatically reduced the number of cells expressing SPRY2. CONCLUSIONS ECS stimulates long-lasting increases in glial proliferation within the ILPFC. ECS also decreases SPRY2 expression in the same region, an effect that might contribute to increased glial proliferation.
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Affiliation(s)
- Dost Ongür
- Department of Psychiatry, Harvard Medical School and McLean Hospital, Belmont, Massachusetts 02478, USA.
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76
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Martínez N, García-Domínguez CA, Domingo B, Oliva JL, Zarich N, Sánchez A, Gutiérrez-Eisman S, Llopis J, Rojas JM. Sprouty2 binds Grb2 at two different proline-rich regions, and the mechanism of ERK inhibition is independent of this interaction. Cell Signal 2007; 19:2277-85. [PMID: 17689925 DOI: 10.1016/j.cellsig.2007.07.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 06/29/2007] [Accepted: 07/02/2007] [Indexed: 11/19/2022]
Abstract
Sprouty2 has been widely implicated in the negative regulation of the fibroblast growth factor receptor-extracellular regulated kinase (ERK) pathway. Sprouty2 directly interacts with the adapter protein Grb2, member of the receptor tyrosine kinase-induced signaling pathways. In considering the functional role of Grb2, we investigated whether the interaction with this protein was responsible for ERK pathway inhibition. We found that the binding between Sprouty2 and Grb2 is constitutive, independent of Sprouty2 tyrosine phosphorylation, although it is increased when fibroblast growth factor receptor is activated. This connection is mediated by the N-terminal SH3 domain of Grb2 and two Sprouty2 proline-rich stretches (residues 59-64 and 303-307). Most importantly, a double Sprouty2 mutant (hSpry2 P59AP304A), which is unable to bind Grb2, developed at a similar inhibition level of fibroblast growth factor receptor-ERK pathway than that which originated from Sprouty2 wt. These results are evidence that the Sprouty2 mechanism of ERK inhibition is independent of Grb2 binding.
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Affiliation(s)
- Natalia Martínez
- Unidad de Biología Celular, Centro Nacional de Microbiología, Instituto de Salud Carlos III, carretera Majadahonda-Pozuelo, Km 2, Majadahonda-28220, Madrid, Spain
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77
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Sutterlüty H, Mayer CE, Setinek U, Attems J, Ovtcharov S, Mikula M, Mikulits W, Micksche M, Berger W. Down-regulation of Sprouty2 in non-small cell lung cancer contributes to tumor malignancy via extracellular signal-regulated kinase pathway-dependent and -independent mechanisms. Mol Cancer Res 2007; 5:509-20. [PMID: 17510316 DOI: 10.1158/1541-7786.mcr-06-0273] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sprouty (Spry) proteins function as inhibitors of receptor tyrosine kinase signaling mainly by interfering with the Ras/Raf/mitogen-activated protein kinase cascade, a pathway known to be frequently deregulated in human non-small cell lung cancer (NSCLC). In this study, we show a consistently lowered Spry2 expression in NSCLC when compared with the corresponding normal lung epithelium. Based on these findings, we investigated the influence of Spry2 expression on the malignant phenotype of NSCLC cells. Ectopic expression of Spry2 antagonized mitogen-activated protein kinase activity and inhibited cell migration in cell lines homozygous for K-Ras wild type, whereas in NSCLC cells expressing mutated K-Ras, Spry2 failed to diminish extracellular signal-regulated kinase (ERK) phosphorylation. Nonetheless, Spry2 significantly reduced cell proliferation in all investigated cell lines and blocked tumor formation in mice. Accordingly, a Spry2 mutant unable to inhibit ERK phosphorylation reduced cell proliferation significantly but less pronounced compared with the wild-type protein. Therefore, we conclude that Spry2 interferes with ERK phosphorylation and another yet unidentified pathway. Our results suggest that Spry2 plays a role as tumor suppressor in NSCLC by antagonizing receptor tyrosine kinase-induced signaling at different levels, indicating feasibility for the usage of Spry in targeted gene therapy of NSCLC.
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Affiliation(s)
- Hedwig Sutterlüty
- Institute of Cancer Research, Medical University Vienna, Borschkegasse 8a, 1090 Vienna, Austria.
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78
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Basson MA, Watson-Johnson J, Shakya R, Akbulut S, Hyink D, Costantini FD, Wilson PD, Mason IJ, Licht JD. Branching morphogenesis of the ureteric epithelium during kidney development is coordinated by the opposing functions of GDNF and Sprouty1. Dev Biol 2006; 299:466-77. [PMID: 17022962 DOI: 10.1016/j.ydbio.2006.08.051] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 05/23/2006] [Accepted: 08/15/2006] [Indexed: 11/26/2022]
Abstract
Branching of ureteric bud-derived epithelial tubes is a key morphogenetic process that shapes development of the kidney. Glial cell line-derived neurotrophic factor (GDNF) initiates ureteric bud formation and promotes subsequent branching morphogenesis. Exactly how GDNF coordinates branching morphogenesis is unclear. Here we show that the absence of the receptor tyrosine kinase antagonist Sprouty1 (Spry1) results in irregular branching morphogenesis characterized by both increased number and size of ureteric bud tips. Deletion of Spry1 specifically in the epithelium is associated with increased epithelial Wnt11 expression as well as increased mesenchymal Gdnf expression. We propose that Spry1 regulates a Gdnf/Ret/Wnt11-positive feedback loop that coordinates mesenchymal-epithelial dialogue during branching morphogenesis. Genetic experiments indicate that the positive (GDNF) and inhibitory (Sprouty1) signals have to be finely balanced throughout renal development to prevent hypoplasia or cystic hyperplasia. Epithelial cysts develop in Spry1-deficient kidneys that share several molecular characteristics with those observed in human disease, suggesting that Spry1 null mice may be useful animal models for cystic hyperplasia.
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Affiliation(s)
- M Albert Basson
- Division of Hematology/Oncology, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
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79
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Abstract
The ureteric bud (UB) is an outgrowth of the Wolffian duct, which undergoes a complex process of growth, branching, and remodeling, to eventually give rise to the entire urinary collecting system during kidney development. Understanding the mechanisms that control this process is a fascinating problem in basic developmental biology, and also has considerable medical significance. Over the past decade, there has been significant progress in our understanding of renal branching morphogenesis and its regulation, and this review focuses on several areas in which there have been recent advances. The first section deals with the normal process of UB branching morphogenesis, and methods that have been developed to better observe and describe it. The next section discusses a number of experimental methodologies, both established and novel, that make kidney development in the mouse a powerful and attractive experimental system. The third section discusses some of the cellular processes that are likely to underlie UB branching morphogenesis, as well as recent data on cell lineages within the growing UB. The fourth section summarizes our understanding of the roles of two groups of growth factors that appear to be particularly important for the regulation of UB outgrowth and branching: GDNF and FGFs, which stimulate this process via tyrosine kinase receptors, and members of the TGFbeta family, including BMP4 and Activin A, which generally inhibit UB formation and branching.
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Affiliation(s)
- Frank Costantini
- Department of Genetics and Development, Columbia University Medical Center, 701 W. 168th St. New York, NY 10032, USA.
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80
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Zhao TY, Zou SP, Alimova YV, Wang G, Hauser KF, Ghandour MS, Knapp PE. Short interfering RNA-induced gene silencing is transmitted between cells from the mammalian central nervous system. J Neurochem 2006; 98:1541-50. [PMID: 16923165 PMCID: PMC4030304 DOI: 10.1111/j.1471-4159.2006.03974.x] [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: 11/28/2022]
Abstract
Although short interfering RNA (siRNA)-induced gene silencing can be transmitted between cells in plants and in Caenorhabditis elegans, this phenomenon has been barely studied in mammalian cells. Both immortalized oligodendrocytes and SNB19 glioblastoma cells were transfected with siRNA constructs for phosphatase and tensin homolog deleted on chromosome 10 (PTEN) or Akt/protein kinase B (Akt). Co-cultures were established between silenced cells and non-silenced cells which were hygromycin resistant and/or expressed green fluorescent protein. After fluorescence sorting or hygromycin selection to remove the silenced cells, the expression of PTEN or Akt genes in the originally unsilenced cells was in all cases significantly decreased. Importantly, silencing did not occur in transwell culture studies, suggesting that transmission of the silencing signal requires a close association between cells. These results provide the first direct demonstration that an siRNA-induced silencing signal can be transmitted between mammalian CNS cells.
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Affiliation(s)
- Tian-Yong Zhao
- Department of Anatomy and Neurobiology, Univ. Kentucky College of Medicine, Lexington, KY 40536-0298, USA
| | - Shi-Ping Zou
- Department of Anatomy and Neurobiology, Univ. Kentucky College of Medicine, Lexington, KY 40536-0298, USA
| | - Yelena V. Alimova
- Department of Anatomy and Neurobiology, Univ. Kentucky College of Medicine, Lexington, KY 40536-0298, USA
| | - Guoying Wang
- State Key Lab of Agrobiotechnology, China Agricultural University, Beijing 100094, P.R.C
| | - Kurt F. Hauser
- Department of Anatomy and Neurobiology, Univ. Kentucky College of Medicine, Lexington, KY 40536-0298, USA
| | - M. Said Ghandour
- UMR 7004, Institut de Physique Biologique, CNRS, Faculté de Médecine, Strasbourg, FR
| | - Pamela E. Knapp
- Department of Anatomy and Neurobiology, Univ. Kentucky College of Medicine, Lexington, KY 40536-0298, USA
- Corresponding Author: Pamela E. Knapp, Ph.D., Dept. Anatomy and Neurobiology, 800 Rose St. MS209, University of Kentucky, Lexington, KY 40536-0298, 859-323-3517, phone 859-323-5946, FAX
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