1
|
Spassov DS, Ruiz-Saenz A, Piple A, Moasser MM. A Dimerization Function in the Intrinsically Disordered N-Terminal Region of Src. Cell Rep 2019; 25:449-463.e4. [PMID: 30304684 PMCID: PMC6226010 DOI: 10.1016/j.celrep.2018.09.035] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 07/09/2018] [Accepted: 09/12/2018] [Indexed: 01/30/2023] Open
Abstract
The mode of regulation of Src kinases has been elucidated by crystallographic studies identifying conserved structured protein modules involved in an orderly set of intramolecular associations and ligand interactions. Despite these detailed insights, much of the complex behavior and diversity in the Src family remains unexplained. A key missing piece is the function of the unstructured N-terminal region. We report here the function of the N-terminal region in binding within a hydrophobic pocket in the kinase domain of a dimerization partner. Dimerization substantially enhances autophosphorylation and phosphorylation of selected substrates, and interfering with dimerization is disruptive to these functions. Dimerization and Y419 phosphorylation are codependent events creating a bistable switch. Given the versatility inherent in this intrinsically disordered region, its multisite phosphorylations, and its divergence within the family, the unique domain likely functions as a central signaling hub overseeing much of the activities and unique functions of Src family kinases. Spassov et al. report that Src exists in cells and functions as a dimer and that dimerization and autophosphorylation are codependent events. Through a comprehensive structure-function analysis, they show that the dimer is an asymmetric dimer held through the interaction of the myristoylated N-terminal unique domain of one partner with a hydrophobic pocket in the kinase domain of another.
Collapse
Affiliation(s)
- Danislav S Spassov
- Department of Medicine, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Ana Ruiz-Saenz
- Department of Medicine, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Amit Piple
- Department of Medicine, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Mark M Moasser
- Department of Medicine, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA.
| |
Collapse
|
2
|
Cai ML, Wang MY, Zhang CH, Wang JX, Liu H, He HW, Zhao WL, Xia GM, Shao RG. Role of co- and post-translational modifications of SFKs in their kinase activation. J Drug Target 2019; 28:23-32. [PMID: 31094236 DOI: 10.1080/1061186x.2019.1616297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Src family kinases (SFKs) are non-receptor tyrosine kinases and are involved in various cellular functions (proliferation, differentiation, migration, survival and invasion) by regulating downstream pathways. Considerable evidence suggests that co- and post-translational modifications are highly related to the activation of SFKs and their downstream signals. How SFKs are activated and how their subsequent cascades were regulated has been reviewed in previous reports. However, the contribution of co- and post-translational modification to SFKs activation has not been fully elucidated. This review focuses on the effect of these modifications on SFKs activity according to structural and biochemical studies and uncovers the significance of co-and post-translational modifications in the regulation of SFKs activity.
Collapse
Affiliation(s)
- Mei-Lian Cai
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Meng-Yan Wang
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Cong-Hui Zhang
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Jun-Xia Wang
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Hong Liu
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Hong-Wei He
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Wu-Li Zhao
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Gui-Ming Xia
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Rong-Guang Shao
- China Academy of Medical Sciences, Key Laboratory of Antibiotic Bioengineering, Ministry of Health, Laboratory of Oncology, Institute of Medicinal Biotechnology, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| |
Collapse
|
3
|
Mohammad IL, Mateos B, Pons M. The disordered boundary of the cell: emerging properties of membrane-bound intrinsically disordered proteins. Biomol Concepts 2019; 10:25-36. [DOI: 10.1515/bmc-2019-0003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 01/28/2019] [Indexed: 12/12/2022] Open
Abstract
AbstractWe define the disordered boundary of the cell (DBC) as the system formed by membrane tethered intrinsically disordered protein regions, dynamically coupled to the underlying membrane.The emerging properties of the DBC makes it a global system of study, which cannot be understood from the individual properties of their components. Similarly, the properties of lipid bilayers cannot be understood from just the sum of the properties of individual lipid molecules.The highly anisotropic confined environment, restricting the position and orientation of interacting sites, is affecting the properties of individual disordered proteins. In fact, the collective effect caused by high concentrations of disordered proteins extend beyond the sum of individual effects.Examples of emerging properties of the DBC include enhanced protein-protein interactions, protein-driven phase separations, Z-compartmentalization, and protein modulated electrostatics.
Collapse
Affiliation(s)
- Irrem-Laareb Mohammad
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, 08028Barcelona, Spain
| | - Borja Mateos
- Max F. Perutz Laboratories, Department of Computational and Structural Biology, University of Vienna, Campus Vienna Biocenter 5, 1030Vienna, Austria
| | - Miquel Pons
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, 08028Barcelona, Spain
| |
Collapse
|
4
|
Le Roux AL, Mohammad IL, Mateos B, Arbesú M, Gairí M, Khan FA, Teixeira JMC, Pons M. A Myristoyl-Binding Site in the SH3 Domain Modulates c-Src Membrane Anchoring. iScience 2019; 12:194-203. [PMID: 30690395 PMCID: PMC6354742 DOI: 10.1016/j.isci.2019.01.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 11/04/2018] [Accepted: 01/04/2019] [Indexed: 12/25/2022] Open
Abstract
The c-Src oncogene is anchored to the cytoplasmic membrane through its N-terminal myristoylated SH4 domain. This domain is part of an intramolecular fuzzy complex with the SH3 and Unique domains. Here we show that the N-terminal myristoyl group binds to the SH3 domain in the proximity of the RT loop, when Src is not anchored to a lipid membrane. Residues in the so-called Unique Lipid Binding Region modulate this interaction. In the presence of lipids, the myristoyl group is released from the SH3 domain and inserts into the lipid membrane. The fuzzy complex with the SH4 and Unique domains is retained in the membrane-bound form, placing the SH3 domain close to the membrane surface and restricting its orientation. The apparent affinity of myristoylated proteins containing the SH4, Unique, and SH3 domains is modulated by these intramolecular interactions, suggesting a mechanism linking c-Src activation and membrane anchoring.
Collapse
Affiliation(s)
- Anabel-Lise Le Roux
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Irrem-Laareb Mohammad
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Borja Mateos
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Miguel Arbesú
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Margarida Gairí
- NMR Facility, Scientific and Technological Centers, Universitat de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Farman Ali Khan
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Department of Biochemistry, Abdul Wali Khan University, Mardan 23200, Pakistan
| | - João M C Teixeira
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Miquel Pons
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, Baldiri Reixac, 10-12, 08028 Barcelona, Spain.
| |
Collapse
|
5
|
Singh DK, Deshmukh RK, Narayanan PK, Shivaji S, Siva AB. SRC family kinases in hamster spermatozoa: evidence for the presence of LCK. Reproduction 2017; 153:655-669. [PMID: 28250239 DOI: 10.1530/rep-16-0591] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 02/03/2017] [Accepted: 02/28/2017] [Indexed: 01/16/2023]
Abstract
Sperm capacitation is a prerequisite for successful fertilization. Increase in tyrosine phosphorylation is considered the hallmark of capacitation and attempts to understand its regulation are ongoing. In this regard, we attempted to study the role of SRC family kinases (SFKs) in the hamster sperm functions. Interestingly, we found the presence of the lymphocyte-specific protein tyrosine kinase, LCK, in mammalian spermatozoa and further characterized it in terms of its localization and function. LCK was found in spermatozoa of several species, and its transcript was identified in the hamster testis. Autophosphorylation of LCK at the Y394 residue increased as capacitation progressed, indicating an upregulation of LCK activity during capacitation. Inhibition of LCK (and perhaps the other SFKs) with the use of a specific inhibitor showed a significant decrease in protein tyrosine phosphorylation of several proteins, implying LCK/SFKs as key tyrosine kinase(s) regulating tyrosine phosphorylation during hamster sperm capacitation. Dihydrolipoamide dehydrogenase was identified as a substrate for LCK/SFK. LCK/SFKs inhibition significantly reduced the percentage fertilization (in vitro) but had no effect on sperm motility, hyperactivation and acrosome reaction. In summary, this is the first report on the presence of LCK, an SFK of hematopoietic lineage in spermatozoa besides being the first study on the role of SFKs in the spermatozoa of Syrian hamsters.
Collapse
Affiliation(s)
| | | | | | - Sisinthy Shivaji
- CSIR-Centre for Cellular and Molecular BiologyHyderabad 500007, India
| | | |
Collapse
|
6
|
Chojnacka K, Mruk DD. The Src non-receptor tyrosine kinase paradigm: New insights into mammalian Sertoli cell biology. Mol Cell Endocrinol 2015; 415:133-42. [PMID: 26296907 DOI: 10.1016/j.mce.2015.08.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 07/27/2015] [Accepted: 08/09/2015] [Indexed: 11/23/2022]
Abstract
Src kinases are non-receptor tyrosine kinases that phosphorylate diverse substrates, which control processes such as cell proliferation, differentiation and survival; cell adhesion; and cell motility. c-Src, the prototypical member of this protein family, is widely expressed by several organs that include the testis. In the seminiferous epithelium of the adult rat testis, c-Src is highest at the tubule lumen during the release of mature spermatids. Other studies show that testosterone regulates spermatid adhesion to Sertoli cells via c-Src, indicating Src phosphorylates key substrates that prompt the disassembly of Sertoli cell-spermatid junctions. A more recent in vitro study reveals that c-Src participates in the internalization of proteins that constitute the blood-testis barrier, which is present between Sertoli cells, suggesting a similar mechanism of junction disassembly is at play during spermiation. In this review, we discuss recent findings on c-Src, with an emphasis on its role in spermatogenesis in the mammalian testis.
Collapse
Affiliation(s)
| | - Dolores D Mruk
- Center for Biomedical Research, Population Council, New York, USA.
| |
Collapse
|
7
|
He Y, Ren Y, Wu B, Decourt B, Lee AC, Taylor A, Suter DM. Src and cortactin promote lamellipodia protrusion and filopodia formation and stability in growth cones. Mol Biol Cell 2015. [PMID: 26224308 PMCID: PMC4569314 DOI: 10.1091/mbc.e15-03-0142] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
How Src tyrosine kinase and cortactin control actin organization and dynamics in neuronal growth cones is not well understood. Using multiple high-resolution imaging techniques, this study shows that Src and cortactin control the persistence of lamellipodial protrusion as well as the formation, stability, and elongation of filopodia in growth cones. Src tyrosine kinases have been implicated in axonal growth and guidance; however, the underlying cellular mechanisms are not well understood. Specifically, it is unclear which aspects of actin organization and dynamics are regulated by Src in neuronal growth cones. Here, we investigated the function of Src2 and one of its substrates, cortactin, in lamellipodia and filopodia of Aplysia growth cones. We found that up-regulation of Src2 activation state or cortactin increased lamellipodial length, protrusion time, and actin network density, whereas down-regulation had opposite effects. Furthermore, Src2 or cortactin up-regulation increased filopodial density, length, and protrusion time, whereas down-regulation promoted lateral movements of filopodia. Fluorescent speckle microscopy revealed that rates of actin assembly and retrograde flow were not affected in either case. In summary, our results support a model in which Src and cortactin regulate growth cone motility by increasing actin network density and protrusion persistence of lamellipodia by controlling the state of actin-driven protrusion versus retraction. In addition, both proteins promote the formation and stability of actin bundles in filopodia.
Collapse
Affiliation(s)
- Yingpei He
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Yuan Ren
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Bingbing Wu
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Boris Decourt
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Aih Cheun Lee
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Aaron Taylor
- Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907
| | - Daniel M Suter
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907 Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907 )
| |
Collapse
|
8
|
Bragado MJ, Gil MC, Martin-Hidalgo D, Hurtado de Llera A, Bravo N, Moreno AD, Garcia-Marin LJ. Src family tyrosine kinase regulates acrosome reaction but not motility in porcine spermatozoa. Reproduction 2012; 144:67-75. [DOI: 10.1530/rep-11-0075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
During the capacitation process, spermatozoa acquire the ability to fertilize an oocyte, and upregulation of cAMP-dependent protein tyrosine phosphorylation occurs. Recently, Src family tyrosine kinase (SFK) has been involved in spermatozoa capacitation as a key PKA-dependent tyrosine kinase in several species. This work investigates the expression and role of SFK in porcine spermatozoa. SFK members Lyn and Yes are identified in porcine spermatozoa by western blotting as well as two proteins named SFK1 and SFK2 were also detected by their tyrosine 416 phosphorylation, a key residue for SFK activation. Spermatozoa with SFK1 and SFK2 increase their Y416 phosphorylation time-dependently under capacitating conditions compared with noncapacitating conditions. The specific SFK inhibitor SU6656 unaffected porcine spermatozoa motility or viability. Moreover, SFK inhibition in spermatozoa under capacitating conditions leads to a twofold increase in both nonstimulated and calcium-induced acrosome reaction. Our data show that capacitating conditions lead to a time-dependent increase in actin polymerization in boar spermatozoa and that long-term incubation with SFK inhibitor causes a reduction in the F-actin content. In summary, this work shows that the SFK members Lyn and Yes are expressed in porcine spermatozoa and that SFK1 and SFK2 are phosphorylated (activated) during capacitation. Our results point out the important role exerted by SFK in the acrosome reaction, likely mediated in part by its involvement in the actin polymerization process that accompanies capacitation, and rule out its involvement in porcine spermatozoa motility.
Collapse
|
9
|
Martin DDO, Beauchamp E, Berthiaume LG. Post-translational myristoylation: Fat matters in cellular life and death. Biochimie 2011; 93:18-31. [PMID: 21056615 DOI: 10.1016/j.biochi.2010.10.018] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 10/23/2010] [Indexed: 01/15/2023]
Abstract
Myristoylation corresponds to the irreversible covalent linkage of the 14-carbon saturated fatty acid, myristic acid, to the N-terminal glycine of many eukaryotic and viral proteins. It is catalyzed by N-myristoyltransferase. Typically, the myristate moiety participates in protein subcellular localization by facilitating protein-membrane interactions as well as protein-protein interactions. Myristoylated proteins are crucial components of a wide variety of functions, which include many signalling pathways, oncogenesis or viral replication. Initially, myristoylation was described as a co-translational reaction that occurs after the removal of the initiator methionine residue. However, it is now well established that myristoylation can also occur post-translationally in apoptotic cells. Indeed, during apoptosis hundreds of proteins are cleaved by caspases and in many cases this cleavage exposes an N-terminal glycine within a cryptic myristoylation consensus sequence, which can be myristoylated. The principal objective of this review is to provide an overview on the implication of myristoylation in health and disease with a special emphasis on post-translational myristoylation. In addition, new advancements in the detection and identification of myristoylated proteins are also briefly reviewed.
Collapse
Affiliation(s)
- Dale D O Martin
- Department of Cell Biology, School of Molecular and Systems Medicine, MSB-5-55, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | | | | |
Collapse
|
10
|
Wright MH, Heal WP, Mann DJ, Tate EW. Protein myristoylation in health and disease. J Chem Biol 2010; 3:19-35. [PMID: 19898886 PMCID: PMC2816741 DOI: 10.1007/s12154-009-0032-8] [Citation(s) in RCA: 182] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 10/05/2009] [Accepted: 10/19/2009] [Indexed: 02/07/2023] Open
Abstract
N-myristoylation is the attachment of a 14-carbon fatty acid, myristate, onto the N-terminal glycine residue of target proteins, catalysed by N-myristoyltransferase (NMT), a ubiquitous and essential enzyme in eukaryotes. Many of the target proteins of NMT are crucial components of signalling pathways, and myristoylation typically promotes membrane binding that is essential for proper protein localisation or biological function. NMT is a validated therapeutic target in opportunistic infections of humans by fungi or parasitic protozoa. Additionally, NMT is implicated in carcinogenesis, particularly colon cancer, where there is evidence for its upregulation in the early stages of tumour formation. However, the study of myristoylation in all organisms has until recently been hindered by a lack of techniques for detection and identification of myristoylated proteins. Here we introduce the chemistry and biology of N-myristoylation and NMT, and discuss new developments in chemical proteomic technologies that are meeting the challenge of studying this important co-translational modification in living systems.
Collapse
Affiliation(s)
- Megan H. Wright
- Chemical Biology Centre, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Chemistry, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Life Sciences, Imperial College London, Exhibition Rd., London, SW72AZ UK
| | - William P. Heal
- Department of Chemistry, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Life Sciences, Imperial College London, Exhibition Rd., London, SW72AZ UK
| | - David J. Mann
- Chemical Biology Centre, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Life Sciences, Imperial College London, Exhibition Rd., London, SW72AZ UK
| | - Edward W. Tate
- Chemical Biology Centre, Imperial College London, Exhibition Rd., London, SW72AZ UK
- Department of Chemistry, Imperial College London, Exhibition Rd., London, SW72AZ UK
| |
Collapse
|
11
|
Mitchell LA, Nixon B, Baker MA, Aitken RJ. Investigation of the role of SRC in capacitation-associated tyrosine phosphorylation of human spermatozoa. ACTA ACUST UNITED AC 2008; 14:235-43. [DOI: 10.1093/molehr/gan007] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
|
12
|
Selvakumar P, Lakshmikuttyamma A, Shrivastav A, Das SB, Dimmock JR, Sharma RK. Potential role of N-myristoyltransferase in cancer. Prog Lipid Res 2007; 46:1-36. [PMID: 16846646 DOI: 10.1016/j.plipres.2006.05.002] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Colorectal cancer is the second leading cause of malignant death, and better preventive strategies are needed. The treatment of colonic cancer remains difficult because of the lack of effective chemotherapeutic agents; therefore it is important to continue to search for cellular functions that can be disrupted by chemotherapeutic drugs resulting in the inhibition of the development and progression of cancer. The current knowledge of the modification of proteins by myristoylation involving myristoyl-CoA: protein N-myristoyltransferase (NMT) is in its infancy. This process is involved in the pathogenesis of cancer. We have reported for the first time that NMT activity and protein expression were higher in human colorectal cancer, gallbladder carcinoma and brain tumors. In addition, an increase in NMT activity appeared at an early stage in colonic carcinogenesis. It is conceivable therefore that NMT can be used as a potential marker for the early detection of cancer. These observations lead to the possibility of developing NMT specific inhibitors, which may be therapeutically useful. We proposed that HSC70 and/or enolase could be used as an anticancer therapeutic target. This review summarized the status of NMT in cancer which has been carried in our laboratory.
Collapse
Affiliation(s)
- Ponniah Selvakumar
- Department of Pathology and Laboratory Medicine, College of Medicine, and Health Research Division, Saskatchewan Cancer Agency, University of Saskatchewan, 20 Campus Drive, Saskatoon, Sask., Canada S7N 4H4
| | | | | | | | | | | |
Collapse
|
13
|
Baker MA, Hetherington L, Aitken RJ. Identification of SRC as a key PKA-stimulated tyrosine kinase involved in the capacitation-associated hyperactivation of murine spermatozoa. J Cell Sci 2006; 119:3182-92. [PMID: 16835269 DOI: 10.1242/jcs.03055] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fertilization of the mammalian oocyte depends on the ability of spermatozoa to undergo a process known as capacitation as they ascend the female reproductive tract. A fundamental feature of this process is a marked increase in tyrosine phosphorylation by an unusual protein kinase A (PKA)-mediated pathway. To date, the identity of the intermediate PKA-activated tyrosine kinase driving capacitation is still unresolved. In this study, we have identified SRC as a candidate intermediate kinase centrally involved in the control of sperm capacitation. Consistent with this conclusion, the SRC kinase inhibitor SU6656 was shown to suppress both tyrosine phosphorylation and hyperactivation in murine spermatozoa. Moreover, SRC co-immunoprecipitated with PKA and this interaction was found to lead to an activating phosphorylation of SRC at position Y416. We have also used difference-in-2D-gel-electrophoresis (DIGE) in combination with mass spectrometry to identify a number of SRC substrates that become phosphorylated during capacitation including enolase, HSP90 and tubulin. Our data further suggest that the activation of SRC during capacitation is negatively controlled by C-terminal SRC kinase. The latter was localized to the acrosome and flagellum of murine spermatozoa by immunocytochemistry, whereas capacitation was associated with an inactivating serine phosphosphorylation of this inhibitory kinase.
Collapse
Affiliation(s)
- Mark A Baker
- The ARC Centre of Excellence in Biotechnology and Development, Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | | | | |
Collapse
|
14
|
Matsuda D, Nakayama Y, Horimoto S, Kuga T, Ikeda K, Kasahara K, Yamaguchi N. Involvement of Golgi-associated Lyn tyrosine kinase in the translocation of annexin II to the endoplasmic reticulum under oxidative stress. Exp Cell Res 2006; 312:1205-17. [PMID: 16527271 DOI: 10.1016/j.yexcr.2006.02.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Revised: 01/10/2006] [Accepted: 02/02/2006] [Indexed: 12/22/2022]
Abstract
Src-family tyrosine kinases, known to participate in signaling pathways of a variety of receptors at the plasma membrane, are found in cellular endomembranes such as the Golgi apparatus and endosomes. Recently, we showed that Lyn, a member of the Src kinases, accumulates on the Golgi apparatus and then traffics to the plasma membrane. We show here that a majority of endogenous Lyn but not c-Src is accumulated in Golgi-enriched heavy-membrane fractions on a sucrose-density gradient, whereas a small amount of endogenous Lyn is present in light-membrane fractions containing the plasma membrane. Inducible expression of kinase-active Lyn, which biosynthetically reaches the Golgi apparatus, triggers tyrosine phosphorylation of proteins including annexin II. Coimmunoprecipitation analyses reveal that Lyn physically associates with annexin II, and an in vitro kinase assay shows that Lyn phosphorylates annexin II directly. Furthermore, stimulation of cells with H2O2 induces tyrosine phosphorylation of annexin II on the Golgi apparatus in a manner that is dependent on the kinase activity of Src kinases, leading to the translocation of annexin II from the Golgi apparatus to the endoplasmic reticulum. Thus, these results suggest that endomembranes containing the Golgi apparatus where Lyn is anchored can serve as a signaling platform under oxidative stress.
Collapse
Affiliation(s)
- Daisuke Matsuda
- Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675, Japan
| | | | | | | | | | | | | |
Collapse
|
15
|
Selvakumar P, Lakshmikuttyamma A, Dimmock JR, Sharma RK. Methionine aminopeptidase 2 and cancer. Biochim Biophys Acta Rev Cancer 2005; 1765:148-54. [PMID: 16386852 DOI: 10.1016/j.bbcan.2005.11.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Revised: 10/21/2005] [Accepted: 11/03/2005] [Indexed: 11/28/2022]
Abstract
Methionine aminopeptidase (MetAP) is a bifunctional protein that plays a critical role in the regulation of post-translational processing and protein synthesis. In yeasts and humans, two proteins are known to possess MetAP activity, which are known as MetAP1 and MetAP2. MetAP2 has attracted much more attention than MetAP1 due to the discovery of MetAP2 as a target molecule of the anti-angiogenic compounds, fumallin and ovalicin. MetAP2 plays an important role in the development of different types of cancer. Recently, we observed a high expression of MetAP2 in human colorectal cancer tissues and colon cancer cell lines. In addition, pp60(c-src) expression was correlated with the expression of MetAP2 and N-myristoyltransferase. In this review, we discuss the recent developments of MetAP2 and its inhibitors. Future detailed studies related to MetAP2 and apoptosis will shed light on the involvement of this enzyme in the regulation of various apoptotic factors.
Collapse
Affiliation(s)
- Ponniah Selvakumar
- Department of Pathology, College of Medicine and Health Research Division, Saskatchewan Cancer Agency, University of Saskatchewan, 20 Campus Drive, Saskatoon, SK, Canada S7N 4H4
| | | | | | | |
Collapse
|
16
|
Abstract
During mitosis, the activity of the c-Src protein tyrosine kinase increases. The tyrosine phosphorylation of a 68 kDa protein (Sam68) also increases at this time, and recent studies have shown that Src and Sam68 interact. Sam68 is highly related to p62, a RasGAP-associated protein, and has homology to RNA-binding proteins. The relationship between p62 and Sam68, and their roles in Src signalling, need to be clarified, but these findings suggest that Src may participate in regulating RNA processing during the cell cycle.
Collapse
Affiliation(s)
- S A Courtneidge
- Differentiation Programme, European Molecular Biology Laboratory, Postfach 16.2209, Meyerhofstrasse 1, 69012 Heidelberg, Germany
| | | |
Collapse
|
17
|
Lee H, Volonte D, Galbiati F, Iyengar P, Lublin DM, Bregman DB, Wilson MT, Campos-Gonzalez R, Bouzahzah B, Pestell RG, Scherer PE, Lisanti MP. Constitutive and growth factor-regulated phosphorylation of caveolin-1 occurs at the same site (Tyr-14) in vivo: identification of a c-Src/Cav-1/Grb7 signaling cassette. Mol Endocrinol 2000; 14:1750-75. [PMID: 11075810 DOI: 10.1210/mend.14.11.0553] [Citation(s) in RCA: 226] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Caveolin-1 was first identified as a phosphoprotein in Rous sarcoma virus (RSV)-transformed chicken embryo fibroblasts. Tyrosine 14 is now thought to be the principal site for recognition by c-Src kinase; however, little is known about this phosphorylation event. Here, we generated a monoclonal antibody (mAb) probe that recognizes only tyrosine 14-phosphorylated caveolin-1. Using this approach, we show that caveolin-1 (Y14) is a specific tyrosine kinase substrate that is constitutively phosphorylated in Src- and Abl-transformed cells and transiently phosphorylated in a regulated fashion during growth factor signaling. We also provide evidence that tyrosine-phosphorylated caveolin-1 is localized at the major sites of tyrosine-kinase signaling, i.e. focal adhesions. By analogy with other signaling events, we hypothesized that caveolin-1 could serve as a docking site for pTyr-binding molecules. In support of this hypothesis, we show that phosphorylation of caveolin-1 on tyrosine 14 confers binding to Grb7 (an SH2-domain containing protein) both in vitro and in vivo. Furthermore, we demonstrate that binding of Grb7 to tyrosine 14-phosphorylated caveolin-1 functionally augments anchorage-independent growth and epidermal growth factor (EGF)-stimulated cell migration. We discuss the possible implications of our findings in the context of signal transduction.
Collapse
Affiliation(s)
- H Lee
- Department of Molecular Pharmacology and The Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Rajala RV, Dehm S, Bi X, Bonham K, Sharma RK. Expression of N-myristoyltransferase inhibitor protein and its relationship to c-Src levels in human colon cancer cell lines. Biochem Biophys Res Commun 2000; 273:1116-20. [PMID: 10891381 DOI: 10.1006/bbrc.2000.3066] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Earlier, we have reported that N-myristoyltransferase (NMT) activity is higher in colonic epithelial neoplasms than in normal appearing colonic tissue and that increase in NMT activity appears at an early stage in colonic carcinogenesis [Magnuson, B., Raju, R. V. S., Moyana, T. N., and Sharma, R. K. (1995) J. Natl. Cancer Inst. 87, 1630-1635]. In this study, we demonstrate increased NMT mRNA in well-differentiated adenocarcinomas. NMT and c-Src mRNA levels were generally elevated in a subset of human colon cancer cell lines. Western blotting analysis employing N-myristoyltransferase inhibitory protein (NIP(71)) antibody demonstrated low levels of NIP(71) in high-expressing c-Src cell lines and high levels of NIP(71) in low-expressing c-Src cell lines. Interestingly, down regulation of c-Src by antisense expression in the HT-29 cell line resulted in increased expression of NIP(71), suggesting c-Src may negatively regulate NIP(71) expression. Furthermore, this is the first study demonstrating the expression of NIP(71) in human colon cancer cell lines and a possible relationship to colon carcinogenesis.
Collapse
Affiliation(s)
- R V Rajala
- Department of Pathology, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan, S7N 4H4, Canada
| | | | | | | | | |
Collapse
|
19
|
Zheng XM, Resnick RJ, Shalloway D. A phosphotyrosine displacement mechanism for activation of Src by PTPalpha. EMBO J 2000; 19:964-78. [PMID: 10698938 PMCID: PMC305636 DOI: 10.1093/emboj/19.5.964] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Protein tyrosine phosphatase alpha (PTPalpha) is believed to dephosphorylate physiologically the Src proto-oncogene at phosphotyrosine (pTyr)527, a critical negative-regulatory residue. It thereby activates Src, and PTPalpha overexpression neoplastically transforms NIH 3T3 cells. pTyr789 in PTPalpha is constitutively phosphorylated and binds Grb2, an interaction that may inhibit PTPalpha activity. We show here that this phosphorylation also specifically enables PTPalpha to dephosphorylate pTyr527. Tyr789-->Phe mutation abrogates PTPalpha-Src binding, dephosphorylation of pTyr527 (although not of other substrates), and neoplastic transformation by overexpressed PTPalpha in vivo. We suggest that pTyr789 enables pTyr527 dephosphorylation by a pilot binding with the Src SH2 domain that displaces the intramolecular pTyr527-SH2 binding. Consistent with model predictions, we find that excess SH2 domains can disrupt PTPalpha-Src binding and can block PTPalpha-mediated dephosphorylation and activation in proportion to their affinity for pTyr789. Moreover, we show that, as predicted by the model, catalytically defective PTPalpha has reduced Src binding in vivo. The displacement mechanism provides another potential control point for physiological regulation of Src-family signal transduction pathways.
Collapse
Affiliation(s)
- X M Zheng
- Department of Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | | | | |
Collapse
|
20
|
Bhandari V, Lim KL, Pallen CJ. Physical and functional interactions between receptor-like protein-tyrosine phosphatase alpha and p59fyn. J Biol Chem 1998; 273:8691-8. [PMID: 9535845 DOI: 10.1074/jbc.273.15.8691] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We have examined the in vivo activity of receptor-like protein-tyrosine phosphatase alpha (PTPalpha) toward p59(fyn), a widely expressed Src family kinase. In a coexpression system, PTPalpha effected a dose-dependent tyrosine dephosphorylation and activation of p59(fyn), where maximal dephosphorylation correlated with a 5-fold increase in kinase activity. PTPalpha expression resulted in increased accessibility of the p59(fyn) SH2 domain, consistent with a PTPalpha-mediated dephosphorylation of the regulatory C-terminal tyrosine residue of p59(fyn). No p59(fyn) dephosphorylation was observed with an enzymatically inactive mutant form of PTPalpha or with another receptor-like PTP, CD45. Many enzyme-linked receptors are complexed with their substrates, and we examined whether PTPalpha and p59(fyn) underwent association. Reciprocal immunoprecipitations and assays detected p59(fyn) and an appropriate kinase activity in PTPalpha immunoprecipitates and PTPalpha and PTP activity in p59(fyn) immunoprecipitates. No association between CD45 and p59(fyn) was detected in similar experiments. The PTPalpha-mediated activation of p59(fyn) is not prerequisite for association since wild-type and inactive mutant PTPalpha bound equally well to p59(fyn). Endogenous PTPalpha and p59(fyn) were also found in association in mouse brain. Together, these results demonstrate a physical and functional interaction of PTPalpha and p59(fyn) that may be of importance in PTPalpha-initiated signaling events.
Collapse
Affiliation(s)
- V Bhandari
- Cell Regulation Laboratory, Institute of Molecular and Cell Biology, National University of Singapore, 30 Medical Drive, Singapore 117609, Republic of Singapore
| | | | | |
Collapse
|
21
|
Curto M, Carrero A, Frankel P, Foster DA. Activation of gene expression by a non-transforming unmyristylated-SH3-deleted mutant of Src is dependent upon Tyr-527. Biochem Biophys Res Commun 1997; 239:681-7. [PMID: 9367828 DOI: 10.1006/bbrc.1997.7510] [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: 02/05/2023]
Abstract
v-Src transcriptionally induces gene expression by activating several transcriptional response elements such as the serum response element (SRE), the 12-O-tetradecanoylphorbol-13-acetate (TPA) response element (TRE), and the c-AMP response element (CRE) found in the promoters of several proliferation-related immediate early genes. We report here that a Src protein, with a deletion in the SH3 domain and lacking a membrane localization signal, strongly activates gene expression mediated by SRE, TRE and CRE transcriptional control elements. This mutant was unable to cause cellular transformation, suggesting that activation of these transcriptional control elements is not sufficient for the induction of a transformed phenotype by Src. Interestingly, the ability of the membrane localization and SH3 deletion mutant to activate gene expression was abolished upon conversion of the C-terminal inhibitory Tyr-527 to Phe. These data suggest the existence of previously unreported Tyr-527-dependent activation of intracellular signals that activate gene expression. These data raise the possibility that Src may exert physiological effects via an interaction between Tyr-527 and an SH2-containing protein that would interact with the phosphorylated form of Tyr-527.
Collapse
Affiliation(s)
- M Curto
- Department of Biological Sciences, Hunter College, City University of New York 10021, USA
| | | | | | | |
Collapse
|
22
|
Zang Q, Lu Z, Curto M, Barile N, Shalloway D, Foster DA. Association between v-Src and protein kinase C delta in v-Src-transformed fibroblasts. J Biol Chem 1997; 272:13275-80. [PMID: 9148947 DOI: 10.1074/jbc.272.20.13275] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In response to the kinase activity of v-Src there is an increase in the membrane association of the novel protein kinase C (PKC) isoform PKC delta (Zang, Q., Frankel, P., and Foster, D. A. (1995) Cell Growth Differ. 6, 1367-1373). We report here that in v-Src-transformed cells PKC delta co-immunoprecipitates with v-Src and is phosphorylated on tyrosine. The tyrosine-phosphorylated PKC delta had reduced enzymatic activity relative to the non-tyrosine-phosphorylated PKC delta from v-Src-transformed cells. The association between Src and PKC delta was dependent upon both an active Src kinase and membrane association. The association between c-Src Y527F and PKC delta was substantially enhanced by mutating a PKC phosphorylation site at Ser-12 in Src to Ala indicating that PKC delta phosphorylation of Src at Ser-12 destabilizes the interaction, possibly in a negative feedback loop. These data demonstrate that upon recruitment of PKC delta to the membrane in v-Src-transformed cells there is the formation of a Src.PKC delta complex in which PKC delta becomes phosphorylated on tyrosine and down-regulated.
Collapse
Affiliation(s)
- Q Zang
- Department of Biological Sciences, Hunter College of the City University of New York, New York, New York 10021, USA
| | | | | | | | | | | |
Collapse
|
23
|
Abstract
N-myristoylation is an acylation process absolutely specific to the N-terminal amino acid glycine in proteins. This maturation process concerns about a hundred proteins in lower and higher eukaryotes involved in oncogenesis, in secondary cellular signalling, in infectivity of retroviruses and, marginally, of other virus types. Thy cytosolic enzyme responsible for this activity, N-myristoyltransferase (NMT), studied since 1987, has been purified from different sources. However, the studies of the specificities of the various NMTs have not progressed in detail except for those relating to the yeast cytosolic enzyme. Still to be explained are differences in species specificity and between various putative isoenzymes, also whether the data obtained from the yeast enzyme can be transposed to other NMTs. The present review discusses data on the various addressing processes subsequent to myristoylation, a patchwork of pathways that suggests myristoylation is only the first step of the mechanisms by which a protein associates with the membrane. Concerning the enzyme itself, there are evidences that NMT is also present in the endoplasmic reticulum and that its substrate specificity is different from that of the cytosolic enzyme(s). These differences have major implications for their differential inhibition and for their respective roles in several pathologies. For instance, the NMTs from mammalians are clearly different from those found in several microorganisms, which raises the question whether the NMT may be a new targets for fungicides. Finally, since myristoylation has a central role in virus maturation and oncogenesis, specific NMT inhibitors might lead to potent antivirus and anticancer agents.
Collapse
Affiliation(s)
- J A Boutin
- Département de Chemie des Peptides, Institut de Recherches Servier 11, Suresnes, France
| |
Collapse
|
24
|
Abstract
Src is the best understood member of a family of 9 tyrosine kinases that regulates cellular responses to extracellular stimuli. Activated mutants of Src are oncogenic. Using Src as an example, and referring to other Src family members where appropriate, this review describes the structure of Src, the functions of the individual domains, the regulation of Src kinase activity in the cell, the selection of substrates, and the biological functions of Src. The review concentrates on developments in the last 6-7 years, and cites data resulting from the isolation and characterization of Src mutants, crystallographic studies of the structures of SH2, SH3 and tyrosine kinase domains, biochemical studies of Src kinase activity and binding properties, and the biology of transgenic and knockout mouse strains.
Collapse
Affiliation(s)
- M T Brown
- Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA
| | | |
Collapse
|
25
|
Magnuson BA, Raju RV, Sharma RK. Distribution of myristoyl-CoA:protein N-myristoyl transferase activity in rabbit intestine. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1300:119-24. [PMID: 8652637 DOI: 10.1016/0005-2760(95)00240-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Myristoyl-CoA:protein N-myristoyl transferase (NMT) attaches the fatty acid, myristate, to the amino-terminal glycine residue of various proteins involved in cellular regulation and/or signal transduction. We report differences in the activity and properties of NMT in New Zealand rabbit small intestine, ascending colon and descending colon. The mucosa of the small intestine, ascending colon and descending colon was assayed for NMT activity using peptides of known myristoylated proteins (pp60src and catalytic subunit of cAMP dependent protein kinase). Total NMT activity per gram tissue was 5-fold higher in the small intestine and 1.5-fold higher in the ascending colon than in the descending colon. Smooth muscle from the colon also contained low levels of NMT activity. NMT activity was 2- to 3-fold higher in the particulate fraction than in the cytosolic fraction of the mucosa in the descending colon. The apparent molecular mass of NMT in the intestine mucosa was 78 kDa.
Collapse
Affiliation(s)
- B A Magnuson
- Department of Pathology, College of Medicine, University of Saskatchewan, Saskatoon, Canada
| | | | | |
Collapse
|
26
|
Tabiti K, Smith DR, Goh HS, Pallen CJ. Increased mRNA expression of the receptor-like protein tyrosine phosphatase alpha in late stage colon carcinomas. Cancer Lett 1995; 93:239-48. [PMID: 7621435 DOI: 10.1016/0304-3835(95)03816-f] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The protein tyrosine phosphatase alpha (PTP alpha) mRNA level in paired samples of late stage (Dukes' D) colorectal tumors and adjacent normal colon mucosa was quantified by RNase protection assays. After normalization against 18S RNA or beta-actin mRNA level, a 2-10-fold increase in PTP alpha mRNA was detected in 10 of 14 tumors (approximately 70%) compared to mucosa. In situ hybridization of digoxigenin-labelled antisense PTP alpha RNA to tumor and mucosa sections produced a signal only in neoplastic cells of the tumor sample, consistent with the high increase in PTP alpha mRNA detected by RNase protection assays of some of the tumors. This is the first report suggesting an association of a protein tyrosine phosphatase with colorectal carcinoma. PTP alpha is a receptor-like PTP thought to be involved in regulating cell proliferation. Its oncogenic properties when overexpressed in cultured fibroblasts suggest that PTP alpha overexpression could contribute to the tumorigenic process in colon carcinoma.
Collapse
Affiliation(s)
- K Tabiti
- Cell Regulation Laboratory, National University of Singapore
| | | | | | | |
Collapse
|
27
|
Taylor SJ, Anafi M, Pawson T, Shalloway D. Functional interaction between c-Src and its mitotic target, Sam 68. J Biol Chem 1995; 270:10120-4. [PMID: 7537265 DOI: 10.1074/jbc.270.17.10120] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The c-Src tyrosine kinase phosphorylates and binds to a 68-kDa RNA-binding protein in mitotic cells. We have examined the mechanism and functional consequence of the interaction of c-Src with this protein, Sam 68 (Src associated in mitosis, 68 kDa). In whole cell homogenates, Sam 68 was the predominant substrate and binding partner of overexpressed c-Src. Mitotic, tyrosine-phosphorylated Sam 68 bound selectively to recombinant SH2 domains with significantly different affinities (c-Src approximately Ras GTPase activating protein > p85 alpha (amino-terminal) > Grb2 >> p85 alpha (COOH-terminal)). In vitro translated Sam 68 also bound selectively to recombinant SH3 domains, with the highest affinity for the Src and p85 alpha SH3 domains. SH3 binding was inhibited by specific Sam 68 peptides. In vitro translated Sam 68 bound directly to immobilized poly(U), and this was inhibited by binding of Src and p85 SH3 domains to Sam 68. The results suggest that the selection of Sam 68 as a mitotic target by c-Src is the result of highly specific interaction with SH2 and SH3 domains and that this interaction may modulate the RNA binding activity of Sam 68.
Collapse
Affiliation(s)
- S J Taylor
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853, USA
| | | | | | | |
Collapse
|
28
|
Erpel T, Courtneidge SA. Src family protein tyrosine kinases and cellular signal transduction pathways. Curr Opin Cell Biol 1995; 7:176-82. [PMID: 7612268 DOI: 10.1016/0955-0674(95)80025-5] [Citation(s) in RCA: 240] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Members of the Src family of protein tyrosine kinases are thought to be involved in signal transduction pathways that control growth and cellular architecture. In recent years it has been shown that they interact with receptor tyrosine kinases (such as the platelet-derived growth factor receptor) and with receptors that themselves lack intrinsic tyrosine kinase activity (such as the interleukin-2 receptor). In some cases they are required for mitogenic signalling by these receptors. They are also activated in response to stress and during mitosis.
Collapse
Affiliation(s)
- T Erpel
- Differentiation Programme, EMBL, Heidelberg, Germany
| | | |
Collapse
|
29
|
Taylor SJ, Shalloway D. An RNA-binding protein associated with Src through its SH2 and SH3 domains in mitosis. Nature 1994; 368:867-71. [PMID: 7512694 DOI: 10.1038/368867a0] [Citation(s) in RCA: 347] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The tyrosine kinase activity of c-Src is stimulated during mitosis by dephosphorylation of its regulatory tyrosine residue. This is associated with increased accessibility of its Src homology-2 (SH2) domain for binding a phosphotyrosine-containing peptide. But physiological targets of activated c-Src in mitosis have not yet been identified. Here we report that a 68K protein (p68) becomes tyrosine-phosphorylated and physically associates with Src during mitosis in mouse fibroblasts. p68 independently binds the Src SH2 and SH3 domains in vitro and both domains are required for p68 phosphorylation and binding in vivo. p68 is closely related to the p62 protein that is associated with the Ras GTPase-activating protein (GAP) and selectively binds, directly or indirectly, polyribonucleotides. Because the Src SH3 domain also binds heterogeneous nuclear ribonucleoprotein K, these results raise the intriguing possibility that c-Src may regulate the processing, trafficking or translation of RNA in a cell-cycle-dependent manner.
Collapse
Affiliation(s)
- S J Taylor
- Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853
| | | |
Collapse
|
30
|
Tsygankov A, Bolen J. The Src family of tyrosine protein kinases in hemopoietic signal transduction. Stem Cells 1993; 11:371-80. [PMID: 7694720 DOI: 10.1002/stem.5530110504] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The Src family of tyrosine protein kinases (TPKs) represents a class of closely related intracellular enzymes that participate in the signal transduction pathways in a variety of hemopoietic cells. The Src TPKs associate with multiple cell surface molecules rendering these receptors capable of activating tyrosine phosphorylation of cellular protein targets. Despite phenotypic differences between various hemopoietic cells, the signal transduction pathways that involve Src TPKs demonstrate clear similarities. Accumulating data on the antigen-induced activation in T cells, B cells, and mast cells indicate that the Src TPKs participate in early antigen receptor responses in these cells.
Collapse
Affiliation(s)
- A Tsygankov
- Department of Molecular Biology, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ 08543-4000
| | | |
Collapse
|