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Manne BK, Münzer P, Badolia R, Walker-Allgaier B, Campbell RA, Middleton E, Weyrich AS, Kunapuli SP, Borst O, Rondina MT. PDK1 governs thromboxane generation and thrombosis in platelets by regulating activation of Raf1 in the MAPK pathway. J Thromb Haemost 2018; 16:1211-1225. [PMID: 29575487 PMCID: PMC5984143 DOI: 10.1111/jth.14005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Indexed: 01/02/2023]
Abstract
Essentials Phosphoinositide 3-kinase and MAPK pathways crosstalk via PDK1. PDK1 is required for adenosine diphosphate-induced platelet activation and thromboxane generation. PDK1 regulates RAF proto-oncogene Ser/Thr kinase (Raf1) activation in the MAPK pathway. Genetic ablation of PDK1 protects against platelet-dependent thrombosis in vivo. SUMMARY Background Platelets are dynamic effector cells with functions that span hemostatic, thrombotic and inflammatory continua. Phosphoinositide-dependent protein kinase 1 (PDK1) regulates protease-activated receptor 4-induced platelet activation and thrombus formation through glycogen synthase kinase3β. However, whether PDK1 also signals through the ADP receptor and its functional importance in vivo remain unknown. Objective To establish the mechanism of PDK1 in ADP-induced platelet activation and thrombosis. Methods We assessed the role of PDK1 on 2MeSADP-induced platelet activation by measuring aggregation, thromboxane generation and phosphorylation events in the presence of BX-795, which inhibits PDK1, or by using platelet-specific PDK1 knockout mice and performing western blot analysis. PDK1 function in thrombus formation was assessed with an in vivo pulmonary embolism model. Results PDK1 inhibition with BX-795 reduced 2-methylthio-ADP (2MeSADP)-induced aggregation of human and murine platelets by abolishing thromboxane generation. Similar results were observed in pdk1-/- mice. PDK1 was also necessary for the phosphorylation of mitogen-activated protein kinase kinase 1/2 (MEK1/2), extracellular signal-regulated kinase 1/2, and cytosolic phospholipase A2, indicating that PDK1 regulates an upstream kinase in the mitogen-activated protein kinase (MAPK) pathway. We next determined that this upstream kinase is Raf-1, a serine/threonine kinase that is necessary for the phosphorylation of MEK1/2, as pharmacological inhibition and genetic ablation of PDK1 were sufficient to prevent Raf1 phosphorylation. Furthermore, in vivo inhibition or genetic ablation of PDK1 protected mice from collagen/epinephrine-induced pulmonary embolism. Conclusion PDK1 governs thromboxane generation and thrombosis in platelets that are stimulated with 2MeSADP by regulating activation of the MAPK pathway.
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Affiliation(s)
- Bhanu Kanth Manne
- Department of Internal Medicine, Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Patrick Münzer
- Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Tübingen, 72076 Germany
| | - Rachit Badolia
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, 19140 USA
| | - Britta Walker-Allgaier
- Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Tübingen, 72076 Germany
| | - Robert A Campbell
- Department of Internal Medicine, Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Elizabeth Middleton
- Department of Internal Medicine, Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Andrew S Weyrich
- Department of Internal Medicine, Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Satya P Kunapuli
- Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA, 19140 USA
| | - Oliver Borst
- Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Tübingen, 72076 Germany
| | - Matthew T. Rondina
- Department of Internal Medicine, Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
- Department of Internal Medicine, GRECC, George E. Wahlen VAMC, Salt Lake City, UT, 84148
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Abstract
INTRODUCTION Gastric cancer remains a major cancer burden in the world, with a poor 5-year survival rate. It is necessary to develop new effective therapeutic strategies to improve the long-term clinical outcome. MicroRNA (miRNA), a class of small non-coding RNA, has been identified as a key regulator of gene expression, and is implicated in the pathogenesis of gastric cancer. AREAS COVERED This review summarizes the role of miRNAs in gastric carcinogenesis, with an emphasis on the expression and function of miR-375 in gastric cancer and beyond. It also discusses the opportunities and challenges of miR-375 as a potential therapeutic target for gastric cancer. The genes targeted by miR-375, including JAK2 and 3'-phosphoinositide dependent protein kinase-1 (PDK1), are also candidates for gastric cancer therapy. EXPERT OPINION Although radical surgery and rational chemotherapy are still the main treatment for gastric cancer, targeting miRNAs, in combination with other conventional therapies, may serve as a promising therapy strategy to improve the clinical outcome.
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Affiliation(s)
- Yanjun Xu
- Zhejiang University School of Medicine, Department of Cell Biology, Program in Molecular Cell Biology, Hangzhou, China
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Lopez-Bergami P, Kim H, Dewing A, Goydos J, Aaronson S, Ronai Z. c-Jun regulates phosphoinositide-dependent kinase 1 transcription: implication for Akt and protein kinase C activities and melanoma tumorigenesis. J Biol Chem 2009; 285:903-13. [PMID: 19910471 DOI: 10.1074/jbc.m109.075630] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Mutations in N-RAS and B-RAF, which commonly occur in melanomas, result in constitutive activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase (ERK) signaling. Active ERK increases expression and activity of the c-Jun transcription factor, linking ERK and Jun N-terminal kinase (JNK) cascades. Here, we show that c-Jun regulates transcription of phosphoinositide-dependent kinase 1 (PDK1) with a concomitant impact on Akt and protein kinase C (PKC) activity and related substrates. Inhibition of c-Jun reduces PDK1 expression and attenuates Akt and PKC activity, which can be restored by exogenous PDK1. c-Jun regulation of PDK1 in melanoma contributes to growth rate and the ability to form tumors in mice. Correspondingly, increased levels of c-Jun in melanoma cell lines coincide with up-regulation of PDK1 and phosphorylation of PKC and Akt. The identification of c-Jun as a transcriptional regulator of PDK1 expression highlights key mechanisms underlying c-Jun oncogenic activity, and provides new insight into the nature of up-regulated Akt and PKC in melanoma.
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Affiliation(s)
- Pablo Lopez-Bergami
- Signal Transduction Program, The Burnham Institute for Medical Research, La Jolla, California 92037, USA
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Ruths D, Muller M, Tseng JT, Nakhleh L, Ram PT. The signaling petri net-based simulator: a non-parametric strategy for characterizing the dynamics of cell-specific signaling networks. PLoS Comput Biol 2008; 4:e1000005. [PMID: 18463702 PMCID: PMC2265486 DOI: 10.1371/journal.pcbi.1000005] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 01/18/2008] [Indexed: 12/27/2022] Open
Abstract
Reconstructing cellular signaling networks and understanding how they work are major endeavors in cell biology. The scale and complexity of these networks, however, render their analysis using experimental biology approaches alone very challenging. As a result, computational methods have been developed and combined with experimental biology approaches, producing powerful tools for the analysis of these networks. These computational methods mostly fall on either end of a spectrum of model parameterization. On one end is a class of structural network analysis methods; these typically use the network connectivity alone to generate hypotheses about global properties. On the other end is a class of dynamic network analysis methods; these use, in addition to the connectivity, kinetic parameters of the biochemical reactions to predict the network's dynamic behavior. These predictions provide detailed insights into the properties that determine aspects of the network's structure and behavior. However, the difficulty of obtaining numerical values of kinetic parameters is widely recognized to limit the applicability of this latter class of methods. Several researchers have observed that the connectivity of a network alone can provide significant insights into its dynamics. Motivated by this fundamental observation, we present the signaling Petri net, a non-parametric model of cellular signaling networks, and the signaling Petri net-based simulator, a Petri net execution strategy for characterizing the dynamics of signal flow through a signaling network using token distribution and sampling. The result is a very fast method, which can analyze large-scale networks, and provide insights into the trends of molecules' activity-levels in response to an external stimulus, based solely on the network's connectivity. We have implemented the signaling Petri net-based simulator in the PathwayOracle toolkit, which is publicly available at http://bioinfo.cs.rice.edu/pathwayoracle. Using this method, we studied a MAPK1,2 and AKT signaling network downstream from EGFR in two breast tumor cell lines. We analyzed, both experimentally and computationally, the activity level of several molecules in response to a targeted manipulation of TSC2 and mTOR-Raptor. The results from our method agreed with experimental results in greater than 90% of the cases considered, and in those where they did not agree, our approach provided valuable insights into discrepancies between known network connectivities and experimental observations.
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Affiliation(s)
- Derek Ruths
- Department of Computer Science, Rice University, Houston, Texas, USA
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Scimè A, Grenier G, Huh MS, Gillespie MA, Bevilacqua L, Harper ME, Rudnicki MA. Rb and p107 regulate preadipocyte differentiation into white versus brown fat through repression of PGC-1alpha. Cell Metab 2005; 2:283-95. [PMID: 16271529 DOI: 10.1016/j.cmet.2005.10.002] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2005] [Revised: 06/28/2005] [Accepted: 10/11/2005] [Indexed: 10/25/2022]
Abstract
The Rb family, Rb, p107, and p130, play important roles in cell cycle control and cellular differentiation, and Rb has been suggested to regulate adipocyte differentiation. We report here that mice lacking p107 displayed a uniform replacement of white adipose tissue (WAT) with brown adipose tissue (BAT). Mutant WAT depots contained mutilocular adipocytes that expressed elevated levels of PGC-1alpha and UCP-1 typical of BAT. WAT from p107-/- mice contained markedly elevated numbers of adipogenic precursors that displayed downregulated expression of pRb. Consistent with the hypothesis that pRb is required for adult adipocyte differentiation, Cre-mediated deletion of Rb in adult primary preadipocytes blocked their differentiation into white adipocytes. Importantly, pRb was observed to bind the PGC-1alpha promoter and repress transcription. Therefore, p107 and pRb regulate PGC-1alpha expression to control the switch between white and brown adipocyte differentiation from a common pool of presumptive adult progenitors in fat tissue.
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Affiliation(s)
- Anthony Scimè
- Molecular Medicine Program, Ottawa Health Research Institute, 501 Smyth Road, Ottawa, Ontario K1H 8L6, Canada
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Longworth MS, Wilson R, Laimins LA. HPV31 E7 facilitates replication by activating E2F2 transcription through its interaction with HDACs. EMBO J 2005; 24:1821-30. [PMID: 15861133 PMCID: PMC1142589 DOI: 10.1038/sj.emboj.7600651] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2004] [Accepted: 03/24/2005] [Indexed: 02/04/2023] Open
Abstract
The E7 proteins of human papillomaviruses (HPVs) contribute to oncogenesis by associating with Rb family members as well class I histone deacetylases (HDACs). The binding of HDACs is also important for the maintenance of viral episomes during the differentiation-dependent productive life cycle. The effects of E7 and other viral proteins on E2F family members were examined in differentiating keratinocytes. E7 was found to specifically activate E2F2 transcription in suprabasal keratinocytes through its ability to bind HDACs. Chromatin immunoprecipitation assays demonstrated that, in differentiating cells, E7 acts to inhibit HDAC binding to the E2F2 promoter resulting in activation of expression. Reduction of E2F2 levels through the use of siRNA confirmed that E2F2 expression facilitated HPV replication but its loss did not affect cell proliferation. Our study demonstrates a mechanism by which binding of HDACs to E7 directly modulates viral replication and identifies E2F2 as a possible target for antiviral therapies.
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Affiliation(s)
- Michelle S Longworth
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Regina Wilson
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Laimonis A Laimins
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Department of Microbiology and Immunology, Northwestern University, Morton 6-693, 303 E Chicago Ave, Chicago, IL 60611, USA. Tel.: +1 312 503 0648; Fax: +1 312 503 0649; E-mail:
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Rodier G, Makris C, Coulombe P, Scime A, Nakayama K, Nakayama KI, Meloche S. p107 inhibits G1 to S phase progression by down-regulating expression of the F-box protein Skp2. ACTA ACUST UNITED AC 2005; 168:55-66. [PMID: 15631990 PMCID: PMC2171673 DOI: 10.1083/jcb.200404146] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cell cycle progression is negatively regulated by the pocket proteins pRb, p107, and p130. However, the mechanisms responsible for this inhibition are not fully understood. Here, we show that overexpression of p107 in fibroblasts inhibits Cdk2 activation and delays S phase entry. The inhibition of Cdk2 activity is correlated with the accumulation of p27, consequent to a decreased degradation of the protein, with no change of Thr187 phosphorylation. Instead, we observed a marked decrease in the abundance of the F-box receptor Skp2 in p107-overexpressing cells. Reciprocally, Skp2 accumulates to higher levels in p107−/− embryonic fibroblasts. Ectopic expression of Skp2 restores p27 down-regulation and DNA synthesis to the levels observed in parental cells, whereas inactivation of Skp2 abrogates the inhibitory effect of p107 on S phase entry. We further show that the serum-dependent increase in Skp2 half-life observed during G1 progression is impaired in cells overexpressing p107. We propose that p107, in addition to its interaction with E2F, inhibits cell proliferation through the control of Skp2 expression and the resulting stabilization of p27.
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Affiliation(s)
- Geneviève Rodier
- Institut de recherche en immunovirologie et cancérologie, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
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Abstract
Activation of cytosolic phosphoinositide-3 kinase (PI-3K) signaling pathway has been well established to regulate gene expression, cell cycle, and survival by feeding signals to the nucleus. In addition, strong evidences accumulated over the past few years indicate the presence of an autonomous inositol lipid metabolism and PI-3K signaling within the nucleus. Much less, however, is known about the role and regulation of this nuclear PI-3K pathway. Components of the PI-3K signaling pathway, including PI 3-kinase and its downstream kinase Akt, have been identified at the nuclear level. Consistent with the presence of a complete PI-3K signaling pathway in the nucleus, we have recently found that phosphoinositide-dependent kinase 1 (PDK1), a kinase functioning downstream of PI-3K and upstream of Akt, is a nucleo-cytoplasmic shuttling protein. In the present review, we update our current knowledge on the regulatory mechanisms and the functional roles of PDK1 nuclear translocation. We also summarize some of the kinase-independent activities of PDK1 in cell signaling.
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Affiliation(s)
- Chintan K Kikani
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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Vanderluit JL, Ferguson KL, Nikoletopoulou V, Parker M, Ruzhynsky V, Alexson T, McNamara SM, Park DS, Rudnicki M, Slack RS. p107 regulates neural precursor cells in the mammalian brain. ACTA ACUST UNITED AC 2004; 166:853-63. [PMID: 15353549 PMCID: PMC2172121 DOI: 10.1083/jcb.200403156] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Here we show a novel function for Retinoblastoma family member, p107 in controlling stem cell expansion in the mammalian brain. Adult p107-null mice had elevated numbers of proliferating progenitor cells in their lateral ventricles. In vitro neurosphere assays revealed striking increases in the number of neurosphere forming cells from p107(-/-) brains that exhibited enhanced capacity for self-renewal. An expanded stem cell population in p107-deficient mice was shown in vivo by (a) increased numbers of slowly cycling cells in the lateral ventricles; and (b) accelerated rates of neural precursor repopulation after progenitor ablation. Notch1 was up-regulated in p107(-/-) neurospheres in vitro and brains in vivo. Chromatin immunoprecipitation and p107 overexpression suggest that p107 may modulate the Notch1 pathway. These results demonstrate a novel function for p107 that is distinct from Rb, which is to negatively regulate the number of neural stem cells in the developing and adult brain.
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