101
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Dong B, Valencia CA, Liu R. Ca(2+)/calmodulin directly interacts with the pleckstrin homology domain of AKT1. J Biol Chem 2007; 282:25131-40. [PMID: 17580302 DOI: 10.1074/jbc.m702123200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AKT kinase, also known as protein kinase B, is a key regulator of cell growth, proliferation, and metabolism. The activation of the AKT signaling pathway is one of the most frequent molecular alterations in a wide variety of human cancers. Dickson and coworkers recently observed that Ca(2+).calmodulin (Ca(2+).CaM) may be a common regulator of AKT1 activation (Deb, T. B., Coticchia, C. M., and Dickson, R. B. (2004) J. Biol. Chem. 279, 38903-38911). In our efforts to scan the mRNA-displayed proteome libraries for Ca(2+).CaM-binding proteins, we found that both human and Caenorhabditis elegans AKT1 kinases bound to CaM in a Ca(2+)-dependent manner (Shen, X., Valencia, C. A., Szostak, J., Dong, B., and Liu, R. (2005) Proc. Natl. Acad. Sci. U. S. A. 102, 5969-5974 and Shen, X., Valencia, C. A., Gao, W., Cotten, S. W., Dong, B., Chen, M., and Liu, R. (2007) submitted for publication). Here we demonstrate that Ca(2+).CaM and human AKT1 were efficiently co-immunoprecipitated, and their interaction was direct rather than mediated by other proteins. The binding is in part attributed to the first 42 residues of the pleckstrin homology (PH) domain, a region that is critical for the recognition of its lipid ligands. The PH domain of human AKT1 can disrupt the complex of the full-length AKT1 with Ca(2+).CaM. In addition, Ca(2+).CaM competes with phosphatidylinositol 3,4,5-trisphophate for interaction with the PH domain of human AKT1. Our findings suggest that Ca(2+).CaM is directly involved in regulating the functions of AKT1, presumably by releasing the activated AKT1 from the plasma membrane and/or prohibiting it from re-association with phosphoinositides on plasma membrane.
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Affiliation(s)
- Biao Dong
- School of Pharmacy and Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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102
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Noguchi M, Ropars V, Roumestand C, Suizu F. Proto‐oncogene TCL1: more than just a coactivator for Akt. FASEB J 2007; 21:2273-84. [PMID: 17360849 DOI: 10.1096/fj.06-7684com] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Serine threonine kinase Akt, also called PKB (protein kinase B), plays a central role in regulating intracellular survival. Deregulation of this Akt signaling pathway underlies various human neoplastic diseases. Recently, the proto-oncogene TCL1 (T cell leukemia 1), with a previously unknown physiological function, was shown to interact with the Akt pleckstrin homology domain, enhancing Akt kinase activity; hence, it functions as an Akt kinase coactivator. In contrast to pathological conditions in which the TCL1 gene is highly activated in various human neoplasmic diseases, the physiological expression of TCL1 is tightly limited to early developmental cells as well as various developmental stages of immune cells. The NBRE (nerve growth factor-responsive element) of the proximal TCL1 promoter sequences can regulate the restricted physiological expression of TCL1 in a negative feedback mechanism. Further, based on the NMR structural studies of Akt-TCL1 protein complexes, an inhibitory peptide, "Akt-in," consisting of the betaA strand of TCL1, has been identified and has therapeutic potential. This review article summarizes and discusses recent advances in the understanding of TCL1-Akt functional interaction in order to clarify the biological action of the proto-oncogene TCL1 family and the development avenues for a suppressive drug specific for Akt, a core intracellular survival regulator.
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Affiliation(s)
- Masayuki Noguchi
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan.
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103
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Parry RV, Riley JL, Ward SG. Signalling to suit function: tailoring phosphoinositide 3-kinase during T-cell activation. Trends Immunol 2007; 28:161-8. [PMID: 17336157 DOI: 10.1016/j.it.2007.02.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 01/29/2007] [Accepted: 02/16/2007] [Indexed: 11/20/2022]
Abstract
Members of the CD28 family of co-receptors are crucial determinants of the outcome of T-cell activation. These receptors interact with ligands in the B7 family and either costimulate or co-inhibit signals through antigen-specific receptors. The T-cell-costimulatory molecules CD28 and inducible costimulator recruit and activate class 1A phosphoinositide 3-kinase (PI3K). Interestingly, the co-inhibitory molecules cytotoxic T lymphocyte antigen-4 and B and T lymphocyte attenuator also interact with class 1A PI3K. However, all co-inhibitory receptors share an ability to oppose activation of the key PI3K effector protein kinase B (also known as Akt). Recent evidence suggests that distinct mechanisms exist to limit Akt activation by different co-inhibitory receptors. This article examines how differential positive or negative regulation of the PI3K-Akt signalling pathway by CD28 family receptors enables functional differences between the receptors.
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Affiliation(s)
- Richard V Parry
- Inflammatory Cell Biology Laboratory, Department of Pharmacy and Pharmacology, University of Bath, Bath, UK.
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104
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Shiojima I, Walsh K. Regulation of cardiac growth and coronary angiogenesis by the Akt/PKB signaling pathway. Genes Dev 2007; 20:3347-65. [PMID: 17182864 DOI: 10.1101/gad.1492806] [Citation(s) in RCA: 285] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Postnatal growth of the heart is primarily achieved through hypertrophy of individual myocytes. Cardiac growth observed in athletes represents adaptive or physiological hypertrophy, whereas cardiac growth observed in patients with hypertension or valvular heart diseases is called maladaptive or pathological hypertrophy. These two types of hypertrophy are morphologically, functionally, and molecularly distinct from each other. The serine/threonine protein kinase Akt is activated by various extracellular stimuli in a phosphatidylinositol-3 kinase-dependent manner and regulates multiple aspects of cellular functions including survival, growth and metabolism. In this review we will discuss the role of the Akt signaling pathway in the heart, focusing on the regulation of cardiac growth, contractile function, and coronary angiogenesis. How this signaling pathway contributes to the development of physiological/pathological hypertrophy and heart failure will also be discussed.
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Affiliation(s)
- Ichiro Shiojima
- Molecular Cardiology, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
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105
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Fleming JM, Desury G, Polanco TA, Cohick WS. Insulin growth factor-I and epidermal growth factor receptors recruit distinct upstream signaling molecules to enhance AKT activation in mammary epithelial cells. Endocrinology 2006; 147:6027-35. [PMID: 16990343 DOI: 10.1210/en.2006-0349] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
IGF-I and epidermal growth factor (EGF) stimulate both normal mammary epithelial cell (MEC) growth and tumorigenesis. Whereas both growth factors increase DNA synthesis in MECs, how they evoke a greater response in combination when they activate similar signaling pathways remains unknown. In the present study, we investigated the signaling pathways by which these mitogens act in concert to increase DNA synthesis. Only EGF activated the MAPK pathway, and no further increase in MAPK activation was observed when both mitogens were added together. Both growth factors activated the phosphatidylinositol-3 kinase pathway, and simultaneous treatment enhanced phosphorylation of both AKT and its downstream target, p70S6K. The enhanced activation of AKT was observed at multiple time points (5 and 15 min) and growth factor concentrations (2.5-100 ng/ml). IGF-I activated AKT via insulin receptor substrate-1 and p85, the regulatory subunit of phosphatidylinositol-3 kinase. Treatment with EGF had no effect on insulin receptor substrate-1; however, it activated the EGF receptor, SHC, and c-Src. EGF treatment caused the association of SHC with Grb2 and Gab2 with phospho-SHC, phospho-Gab1, Grb2, and p85. Interestingly, inhibition of Src activation blocked the ability of EGF, but not IGF-I, to activate AKT. This corresponded with a decrease in phosphorylation of the EGF receptor and its association with phospho-SHC as well as downstream signaling. Unexpectedly, inhibition of Src increased basal MAPK activation. This is the first study to show that EGF and IGF-I use separate upstream components within a given MEC line to enhance AKT phosphorylation, contributing to increased DNA synthesis.
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Affiliation(s)
- Jodie M Fleming
- Department of Animal Sciences, Rutgers, The State University of New Jersey, 108 Foran Hall, 59 Dudley Road, New Brunswick, New Jersey 08901-8520, USA
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106
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Caruso-Neves C, Pinheiro AAS, Cai H, Souza-Menezes J, Guggino WB. PKB and megalin determine the survival or death of renal proximal tubule cells. Proc Natl Acad Sci U S A 2006; 103:18810-5. [PMID: 17121993 PMCID: PMC1693744 DOI: 10.1073/pnas.0605029103] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Renal proximal tubule cells have a remarkable ability to reabsorb large quantities of albumin through megalin-mediated endocytosis. This is an essential process for overall body homeostasis. Overstressing this endocytic system with a prolonged excess of albumin is injurious to proximal tubule cells. How these cells function and protect themselves from injury is unknown. Here, we show that megalin is the sensor that determines whether cells will be protected or injured by albumin. Megalin, through a novel mechanism, binds PKB in a D-3-phosphorylated phospholipid-insensitive manner, anchoring PKB in the luminal plasma membrane. Whereas low doses of albumin are protective, an overload of albumin decreases megalin expression followed by a reduction of plasma membrane PKB, PKB activity, and Bad phosphorylation induced by PKB. The result is albumin-induced apoptosis. These results reveal a model for PKB distribution in the plasma membrane and elucidate mechanisms involved in both the protective and toxic effects of albumin on proximal tubule cells. In addition, our findings suggest a mechanism for the progression of chronic kidney disease to end-stage renal disease.
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Affiliation(s)
- Celso Caruso-Neves
- *Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil 21949-900
- Departments of Physiology and
| | - Ana Acacia S. Pinheiro
- Department of Molecular Microbiology and Immunology, Johns Hopkins University School of Public Health, Baltimore, MD 21205
| | - Hui Cai
- Departments of Physiology and
- Medicine, Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, MD 21205; and
| | - Jackson Souza-Menezes
- *Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil 21949-900
- Departments of Physiology and
| | - William B. Guggino
- Departments of Physiology and
- To whom correspondence should be addressed. E-mail:
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107
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Martelli AM, Nyåkern M, Tabellini G, Bortul R, Tazzari PL, Evangelisti C, Cocco L. Phosphoinositide 3-kinase/Akt signaling pathway and its therapeutical implications for human acute myeloid leukemia. Leukemia 2006; 20:911-28. [PMID: 16642045 DOI: 10.1038/sj.leu.2404245] [Citation(s) in RCA: 262] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The phosphoinositide 3-kinase (PI3K)/Akt signaling pathway is crucial to many aspects of cell growth, survival and apoptosis, and its constitutive activation has been implicated in the both the pathogenesis and the progression of a wide variety of neoplasias. Hence, this pathway is an attractive target for the development of novel anticancer strategies. Recent studies showed that PI3K/Akt signaling is frequently activated in acute myeloid leukemia (AML) patient blasts and strongly contributes to proliferation, survival and drug resistance of these cells. Upregulation of the PI3K/Akt network in AML may be due to several reasons, including FLT3, Ras or c-Kit mutations. Small molecules designed to selectively target key components of this signal transduction cascade induce apoptosis and/or markedly increase conventional drug sensitivity of AML blasts in vitro. Thus, inhibitory molecules are currently being developed for clinical use either as single agents or in combination with conventional therapies. However, the PI3K/Akt pathway is important for many physiological cellular functions and, in particular, for insulin signaling, so that its blockade in vivo might cause severe systemic side effects. In this review, we summarize the existing knowledge about PI3K/Akt signaling in AML cells and we examine the rationale for targeting this fundamental signal transduction network by means of selective pharmacological inhibitors.
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Affiliation(s)
- A M Martelli
- Cell Signalling Laboratory, Dipartimento di Scienze Anatomiche Umane e Fisiopatologia dell'Apparato Locomotore, Sezione di Anatomia Umana, Università di Bologna, Bologna, Italy.
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108
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Hiromura M, Suizu F, Narita M, Kinowaki K, Noguchi M. Identification of nerve growth factor-responsive element of the TCL1 promoter as a novel negative regulatory element. J Biol Chem 2006; 281:27753-64. [PMID: 16835233 DOI: 10.1074/jbc.m602420200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serine/threonine kinase, Akt (protein kinase B) plays a central role in the regulation of intracellular cell survival. Recently, we demonstrated that the proto-oncogene TCL1, overexpressed in human T-cell prolymphocytic leukemia, is an Akt kinase co-activator. Tightly restricted TCL1 gene expression in early developmental cells suggested that the TCL1 gene is regulated at a transcriptional level. To characterize how TCL1 gene expression is regulated, we cloned the 5'-promoter of the TCL1 gene located at human chromosome 14q32. The 5'-TCL1 promoter region contains a TATA box with cis-regulatory elements for Nur77/NGFI-B (nerve growth factor-responsive element (NBRE), CCAAGGTCA), NFkappaB, and fork head transcription factor. Nur77/NGFI-B, an orphan receptor superfamily transcription factor implicated in T-cell apoptosis, is a substrate for Akt. We hypothesized that TCL1 transactivity is regulated through Akt-induced phosphorylation of Nur77/NGFI-B in vivo. In an electrophoretic mobility shift assay with chromosomal immunoprecipitation assays, wild-type Nur77, but not S350A mutant Nur77, could specifically bind to TCL1-NBRE. A luciferase assay demonstrated that TCL1-NBRE is required for inhibition of TCL1 transactivity upon nerve growth factor/platelet-derived growth factor stimulation, which activates Akt and phosphorylates Nur77. Using a chromosomal immunoprecipitation assay with reverse transcription-PCR, nerve growth factor stimulation inhibited binding of endogenous Nur77 to TCL1-NBRE, in turn, suppressing TCL1 gene expression. The results together establish that TCL1-NBRE is a novel negative regulatory element of Nur77 (NGFI-B). To the best of our knowledge, TCL1-NBRE is the first direct target of Nur77 involving the regulation of intracellular cell death survival. This Akt-induced inhibitory mechanism of TCL1 should play an important role in immunological and/or neuronal development in vivo.
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Affiliation(s)
- Makoto Hiromura
- Division of Cancer Biology, Institute for Genetic Medicine, Hokkaido University, Sapporo 060-0815, Japan
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109
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Ikenaka K, Miyata S, Mori Y, Koyama Y, Taneda T, Okuda H, Kousaka A, Tohyama M. Immunohistochemical and western analyses of protein arginine N-methyltransferase 3 in the mouse brain. Neuroscience 2006; 141:1971-82. [PMID: 16797132 DOI: 10.1016/j.neuroscience.2006.05.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2006] [Revised: 05/11/2006] [Accepted: 05/11/2006] [Indexed: 10/24/2022]
Abstract
The distribution of protein arginine N-methyltransferase 3 (PRMT3) was investigated in the mouse brain using indirect immunofluorescence. PRMT3 was observed to be localized in the cell bodies and dendrites of neurons but not in the axons and glial cells, indicating that PRMT3 is involved in neuronal function. The distribution of the immunoreactive neurons in the brain was uneven, indicating that PRMT3 plays a role in specific neuronal systems such as the motor and limbic systems, as well as functions related to the cerebellum. The present ontogenetic analysis of PRMT1 and PRMT3 using Western blot methodology clearly revealed that PRMT3 develops during the perinatal stage and its expression is maintained even in adulthood. PRMT1, on the other hand, is expressed transiently during the early embryonic stage. These findings indicate that PRMT3 is related with neuronal function in both young and adult brains, while PRMT1 has roles in the immature brain, such as the formation of neural circuits.
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Affiliation(s)
- K Ikenaka
- Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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110
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Cutillas PR, Khwaja A, Graupera M, Pearce W, Gharbi S, Waterfield M, Vanhaesebroeck B. Ultrasensitive and absolute quantification of the phosphoinositide 3-kinase/Akt signal transduction pathway by mass spectrometry. Proc Natl Acad Sci U S A 2006; 103:8959-64. [PMID: 16751276 PMCID: PMC1482548 DOI: 10.1073/pnas.0602101103] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The phosphoinositide 3-kinase (PI3K)/Akt pathway controls a vast array of normal physiological processes and is frequently aberrantly activated in cancer, thus identifying PI3K/Akt-signaling components as promising drug targets in oncology. However, implementation of rational cancer therapies for this pathway needs robust and simple tools to stratify patients according to PI3K pathway activation and to validate and measure the impact of targeted inhibition on primary cancer tissues. Herein we present a technique for the quantification of the PI3K/Akt-signaling pathway based on the mass spectrometric measurement of PI3K-dependent protein kinase activity in cell lysates. The concept of this application of MS is to exploit enzymatic activity to amplify the signal of the enzyme under study analogous to the PCR used to amplify nucleic acid sequences. We show that this approach allows quantitative analysis of a cell-signaling pathway with high sensitivity, precision of quantification, and specificity. Due to its special analytical capabilities and potential for multiplexing, this approach could contribute significantly to cell-signaling studies and to the development and implementation of personalized cancer therapies.
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Affiliation(s)
- Pedro R. Cutillas
- Cell Signaling in Cancer Laboratory, Ludwig Institute for Cancer Research, 91 Riding House Street, London W1W 7BS, United Kingdom
- Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
- To whom correspondence may be addressed.
or
| | - Asim Khwaja
- Department of Haematology, Royal Free & University College Medical School, 98 Chenies Mews, London WC1E 6HX, United Kingdom; and
| | - Mariona Graupera
- Cell Signaling in Cancer Laboratory, Ludwig Institute for Cancer Research, 91 Riding House Street, London W1W 7BS, United Kingdom
| | - Wayne Pearce
- Cell Signaling in Cancer Laboratory, Ludwig Institute for Cancer Research, 91 Riding House Street, London W1W 7BS, United Kingdom
| | - Severine Gharbi
- Proteomics Unit, Ludwig Institute for Cancer Research, Gower Street, London WC1E 6BS, United Kingdom
| | - Mike Waterfield
- Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Proteomics Unit, Ludwig Institute for Cancer Research, Gower Street, London WC1E 6BS, United Kingdom
| | - Bart Vanhaesebroeck
- Cell Signaling in Cancer Laboratory, Ludwig Institute for Cancer Research, 91 Riding House Street, London W1W 7BS, United Kingdom
- Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
- To whom correspondence may be addressed.
or
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