1
|
Yan X, Gong X, Lin T, Lin M, Qin P, Ye J, Li H, Hong Q, Li M, Liu Y, Li Y, Wang X, Zhang Y, Ling Y, Cao H, Zhang X, Fang F. Analysis of protein phosphorylation sites in the hypothalamus tissues of pubescent goats. J Proteomics 2022; 260:104574. [DOI: 10.1016/j.jprot.2022.104574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/08/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
|
2
|
Wang M, Han X, Sun W, Li X, Jing G, Zhang X. Actin Filament-Associated Protein 1-Like 1 Mediates Proliferation and Survival in Non-Small Cell Lung Cancer Cells. Med Sci Monit 2018; 24:215-224. [PMID: 29323101 PMCID: PMC5772338 DOI: 10.12659/msm.905900] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The actin filament-associated protein (AFAP) family consists of 3 novel adaptor proteins: AFAP1, AFAP1L1, and AFAP1L2/XB130. Although evidence shows that AFAP1 and AFAP1L2 play an oncogenic role, the effect of AFAP1L1 on tumor cell behavior has not been fully elucidated, and it remains unknown whether AFAP1L1 could be a prognostic marker and/or therapeutic target of lung cancer. MATERIAL AND METHODS Human A549 non-small cell lung cancer (NSCLC) cells were used in this study. AFAP1L1 gene was knocked down by AFAP1L1 short hairpin RNA (shRNA) transfection. Cell proliferation was analyzed using Celigo image cytometry and MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay, cell cycle progression was assessed with flow cytometry, and cell apoptosis was determined by flow cytometry after annexin-n staining. The PathScan intracellular signaling array was used to investigate cancer-related signaling proteins influenced by knocking down AFAP1L1 in A549. RESULTS AFAP1L1 gene expression was successfully inhibited by the AFAP1L1-shRNA transfection. Cell proliferation was inhibited and cell proportions in G1 and G2/M phases were increased, and cell apoptosis was increased in the AFAP1L1-shRNA transfected cells as compared with negative control shRNA transfected cells. Using the PathScan intracellular signaling array, we found that downregulation of AFAP1L1 significantly activated P38 and caspase 3, and inhibited PRAS40 activation. CONCLUSIONS Our data show that AFAP1L1 promotes cell proliferation, accelerates cell cycle progression, and prevents cell apoptosis in lung cancer cells. Therefore, AFAP1L1 might play an oncogenic role in NSCLC.
Collapse
Affiliation(s)
- Meng Wang
- Graduate School, Tianjin Medical University, Tianjin, China (mainland).,Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin, China (mainland)
| | - Xingpeng Han
- Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin, China (mainland)
| | - Wei Sun
- Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin, China (mainland)
| | - Xin Li
- Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin, China (mainland)
| | - Guohui Jing
- Department of Respiratory and Critical Care Medicine, Tianjin Chest Hospital, Tianjin, China (mainland)
| | - Xun Zhang
- Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin, China (mainland)
| |
Collapse
|
3
|
Chen Y, Liu Y, Guo J, Tang T, Gao J, Huang T, Wang B, Liu S. Preparation and Characterization of a Polyclonal Antibody against Human Actin Filament-Associated Protein-120 kD. Int J Mol Sci 2016; 17:ijms17060942. [PMID: 27322249 PMCID: PMC4926475 DOI: 10.3390/ijms17060942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/02/2016] [Accepted: 06/08/2016] [Indexed: 12/17/2022] Open
Abstract
Actin filament-associated protein-120kD (AFAP-120) is an alternatively spliced isoform of actin filament-associated protein-110kD (AFAP-110) and contains an additional neuronal insert (NINS) fragment in addition to identical domains to the AFAP-110. Unlike AFAP-110 widely expressed in tissues, AFAP-120 is specifically expressed in the nervous system and plays a role in organizing dynamic actin structures during neuronal differentiation. However, anti-AFAP-120 antibody is still commercially unavailable, and this may hinder the function research for AFAP-120. In this study, we simultaneously used the ABCpred online server and the BepiPred 1.0 server to predict B-cell epitopes in the exclusive NINS sequence of human AFAP-120 protein, and found that a 16aa-peptide sequence was the consensus epitope predicted by both tools. This peptide was chemically synthesized and used as an immunogen to develop polyclonal antibody against AFAP-120 (anti-AFAP-120). The sensitivity and specificity of anti-AFAP-120 were analyzed with immunoblotting, immunoprecipitation, and immunofluorescence assays. Our results indicated that anti-AFAP-120 could react with over-expressed and endogenous human AFAP-120 protein under denatured condition, but not with human AFAP-110 protein. Moreover, native human AFAP-120 protein could also be recognized by the anti-AFAP-120 antibody. These results suggested that the prepared anit-AFAP-120 antibody would be a useful tool for studying the biochemical and biological functions of AFAP-120.
Collapse
Affiliation(s)
- Yujian Chen
- Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, China.
| | - Yong Liu
- Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, China.
| | - Jiayu Guo
- Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, China.
| | - Tao Tang
- Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, China.
| | - Jian Gao
- Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, China.
| | - Tao Huang
- Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, China.
| | - Bin Wang
- Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, China.
| | - Shaojun Liu
- Department of Neurobiology, Institute of Basic Medical Sciences, Beijing 100850, China.
| |
Collapse
|
4
|
AFAP1 Is a Novel Downstream Mediator of TGF-β1 for CCN2 Induction in Osteoblasts. PLoS One 2015; 10:e0136712. [PMID: 26340021 PMCID: PMC4560384 DOI: 10.1371/journal.pone.0136712] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 08/07/2015] [Indexed: 02/06/2023] Open
Abstract
Background CCN2 acts as an anabolic growth factor to regulate osteoblast differentiation and function. CCN2 is induced by TGF-β1 and acts as a mediator of TGF-β1 induced matrix production in osteoblasts and Src is required for CCN2 induction by TGF-β1; however, the molecular mechanisms that control CCN2 induction in osteoblasts are poorly understood. AFAP1 binds activated forms of Src and can direct the activation of Src in certain cell types, however a role for AFAP1 downstream of TGF-β1 or in osteoblats is undefined. In this study, we investigated the role of AFAP1 for CCN2 induction by TGF-β1 in primary osteoblasts. Results We demonstrated that AFAP1 expression in osteoblasts occurs in a biphasic pattern with maximal expression levels occurring during osteoblast proliferation (~day 3), reduced expression during matrix production/maturation (~day 14–21), an a further increase in expression during mineralization (~day 21). AFAP1 expression is induced by TGF-β1 treatment in osteoblasts during days 7, 14 and 21. In osteoblasts, AFAP1 binds to Src and is required for Src activation by TGF-β1 and CCN2 promoter activity and protein induction by TGF-β1 treatment was impaired using AFAP1 siRNA, indicating the requirement of AFAP1 for CCN2 induction by TGF-β1. We also demonstrated that TGF-β1 induction of extracellular matrix protein collagen XIIa occurs in an AFAP1 dependent fashion. Conclusions This study demonstrates that AFAP1 is an essential downstream signaling component of TGF-β1 for Src activation, CCN2 induction and collagen XIIa in osteoblasts.
Collapse
|
5
|
Cunnick JM, Kim S, Hadsell J, Collins S, Cerra C, Reiser P, Flynn DC, Cho Y. Actin filament-associated protein 1 is required for cSrc activity and secretory activation in the lactating mammary gland. Oncogene 2014; 34:2640-9. [PMID: 25043309 PMCID: PMC4302073 DOI: 10.1038/onc.2014.205] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 04/25/2014] [Accepted: 06/09/2014] [Indexed: 12/12/2022]
Abstract
Actin filament-associated protein 1 (AFAP1) is an adaptor protein of cSrc that binds to filamentous actin and regulates the activity of this tyrosine kinase to affect changes to the organization of the actin cytoskeleton. In breast and prostate cancer cells, AFAP1 has been shown to regulate cellular responses requiring actin cytoskeletal changes such as adhesion, invadopodia formation and invasion. However, a normal physiologic role for AFAP1 has remained elusive. In this study, we generated an AFAP1 knockout mouse model that establishes a novel physiologic role for AFAP1 in lactation. Specifically, these animals displayed a defect in lactation that resulted in an inability to nurse efficiently. Histologically, the mammary glands of the lactating knockout mice were distinguished by the accumulation of large cytoplasmic lipid droplets in the alveolar epithelial cells. There was a reduction in lipid synthesis and the expression of lipogenic genes without a corresponding reduction in the production of β-casein, a milk protein. Furthermore, these defects were associated with histologic and biochemical signs of precocious involution. This study also demonstrated that AFAP1 responds to prolactin, a lactogenic hormone, by forming a complex with cSrc and becoming tyrosine phosphorylated. Taken together, these observations pointed to a defect in secretory activation. Certain characteristics of this phenotype mirrored the defect in secretory activation in the cSrc knockout mouse, but most importantly, the activity of cSrc in the mammary gland was reduced during early lactation in the AFAP1-null mouse and the localization of active cSrc at the apical surface of luminal epithelial cells during lactation was selectively lost in the absence of AFAP1. These data define, for the first time, the requirement of AFAP1 for the spatial and temporal regulation of cSrc activity in the normal breast, specifically for milk production.
Collapse
Affiliation(s)
- J M Cunnick
- Department of Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
| | - S Kim
- Graduate School of Medicine, The Commonwealth Medical College, Scranton, PA, USA
| | - J Hadsell
- Fortis Institute Scranton, Scranton, PA, USA
| | - S Collins
- Department of Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
| | - C Cerra
- Department of Pathology, Pocono Health System, East Stroudsburg, PA, USA
| | - P Reiser
- Department of Pathology, Pocono Health System, East Stroudsburg, PA, USA
| | - D C Flynn
- College of Health Science, University of Delaware, Newark, DE, USA
| | - Y Cho
- Department of Basic Sciences, The Commonwealth Medical College, Scranton, PA, USA
| |
Collapse
|
6
|
Takahashi R, Nagayama S, Furu M, Kajita Y, Jin Y, Kato T, Imoto S, Sakai Y, Toguchida J. AFAP1L1, a novel associating partner with vinculin, modulates cellular morphology and motility, and promotes the progression of colorectal cancers. Cancer Med 2014; 3:759-74. [PMID: 24723436 PMCID: PMC4303145 DOI: 10.1002/cam4.237] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/17/2014] [Accepted: 03/03/2014] [Indexed: 12/18/2022] Open
Abstract
We have previously identified actin filament-associated protein 1-like 1 (AFAP1L1) as a metastasis-predicting marker for spindle cell sarcomas by gene expression profiling, and demonstrated that AFAP1L1 is involved in the cell invasion process by in vitro analyses. However, its precise molecular function has not been fully elucidated, and it remains unknown whether AFAP1L1 could be a prognostic marker and/or therapeutic target of other malignancies. In this study, we found a marked elevation of AFAP1L1 gene expression in colorectal cancer (CRC) tissues as compared to the adjacent normal mucosa. Multivariate analysis revealed that AFAP1L1 was an independent and significant factor for the recurrence of rectal cancers. Moreover, the addition of the AFAP1L1 expression level to the lymph node metastasis status provided more predictive information regarding postoperative recurrence in rectal cancers. AFAP1L1-transduced CRC cells exhibited a rounded shape, increased cell motility on planar substrates, and resistance to anoikis in vitro. AFAP1L1 localized to the ringed structure of the invadopodia, together with vinculin, and AFAP1L1 was identified as a novel associating partner of vinculin by immunoprecipitation assay. AFAP1L1-transduced cells showed accelerated tumor growth in vivo, presumably reflecting the anoikis resistance of these AFAP1L1-expressing cells. Furthermore, the local administration of a siRNA against AFAP1L1 significantly suppressed the in vivo tumor growth of xenografts, suggesting that AFAP1L1 might be a candidate therapeutic target for CRCs. These results suggest that AFAP1L1 plays a role in the progression of CRCs by modulating cell shape and motility and by inhibiting anoikis, presumably through interactions with vinculin-including protein complexes.
Collapse
Affiliation(s)
- Ryo Takahashi
- Department of Tissue Regeneration, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan; Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Reynolds AB, Kanner SB, Bouton AH, Schaller MD, Weed SA, Flynn DC, Parsons JT. SRChing for the substrates of Src. Oncogene 2013; 33:4537-47. [PMID: 24121272 DOI: 10.1038/onc.2013.416] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 08/16/2013] [Accepted: 08/17/2013] [Indexed: 12/12/2022]
Abstract
By the mid 1980's, it was clear that the transforming activity of oncogenic Src was linked to the activity of its tyrosine kinase domain and attention turned to identifying substrates, the putative next level of control in the pathway to transformation. Among the first to recognize the potential of phosphotyrosine-specific antibodies, Parsons and colleagues launched a risky shotgun-based approach that led ultimately to the cDNA cloning and functional characterization of many of today's best-known Src substrates (for example, p85-Cortactin, p110-AFAP1, p130Cas, p125FAK and p120-catenin). Two decades and over 6000 citations later, the original goals of the project may be seen as secondary to the enormous impact of these protein substrates in many areas of biology. At the request of the editors, this review is not restricted to the current status of the substrates, but reflects also on the anatomy of the project itself and some of the challenges and decisions encountered along the way.
Collapse
Affiliation(s)
- A B Reynolds
- Department of Cancer Biology, Vanderbilt University, Nashville, TN, USA
| | - S B Kanner
- Arrowhead Research Corporation, Madison, WI, USA
| | - A H Bouton
- Departments of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - M D Schaller
- Department of Biochemistry, 3124 HSN, Robert C. Byrd Health Sciences Center, West Virginia University School of Medicine, Morgantown, WV, USA
| | - S A Weed
- Department of Neurobiology and Anatomy, 1833 Mary Babb Randolph Cancer Center, Robert C. Byrd Health Sciences Center, West Virginia University School of Medicine, Morgantown, WV, USA
| | - D C Flynn
- Department of Medical Lab Sciences, College of Health Sciences, University of Delaware, Newark, DE, USA
| | - J T Parsons
- Departments of Microbiology, Immunology and Cancer Biology, University of Virginia Cancer Center, Charlottesville, VA, USA
| |
Collapse
|
8
|
Bourguignon LYW, Wong G, Earle CA, Xia W. Interaction of low molecular weight hyaluronan with CD44 and toll-like receptors promotes the actin filament-associated protein 110-actin binding and MyD88-NFκB signaling leading to proinflammatory cytokine/chemokine production and breast tumor invasion. Cytoskeleton (Hoboken) 2011; 68:671-93. [PMID: 22031535 DOI: 10.1002/cm.20544] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 09/30/2011] [Accepted: 10/12/2011] [Indexed: 12/23/2022]
Abstract
Both high and low molecular weight hyaluronan (HMW-HA vs. LMW-HA) exist in various tissues and cells. In this study, we investigated LMW-HA-mediated CD44 interaction with Toll-like receptors (TLRs), the actin filament-associated protein (AFAP-110), and a myeloid differentiation factor (MyD88) in breast tumor cells (MDA-MB-231 cells). Our data indicate that LMW-HA (but not HMW-HA) preferentially stimulates a physical association between CD44 and TLRs followed by a concomitant recruitment of AFAP-110 and MyD88 into receptor-containing complexes in breast tumor cells. LMW-HA-activated AFAP-110 then binds to filamentous actin (F-actin) resulting in MyD88/nuclear factor-κB (NF-κB) nuclear translocation, NF-κB-specific transcription, and target gene [interleukine 1β and interleukine-8 (IL-1β and IL-8)] expression. These signaling events lead to proinflammatory cytokine/chemokine production in the breast tumor cells. AFAP-110-F-actin (activated by LMW-HA) also promotes tumor cell invasion. Downregulation of AFAP-110 or MyD88 by transfecting breast tumor cells with AFAP-110 siRNA or MyD88 siRNA, respectively not only blocks the ability of LMW-HA to stimulate AFAP-110-actin function, but also impairs MyD88-NF-κB nuclear translocation and NF-κB transcriptional activation. Consequently, both IL-1β/IL-8 production and tumor cell invasion are impaired. Taken together, these findings suggest that LMW-HA plays an important role in CD44-TLR-associated AFAP-110-actin interaction and MyD88-NF-κB signaling required for tumor cell behaviors, which may contribute to the progression of breast cancer.
Collapse
|
9
|
|
10
|
Snyder BN, Cho Y, Qian Y, Coad JE, Flynn DC, Cunnick JM. AFAP1L1 is a novel adaptor protein of the AFAP family that interacts with cortactin and localizes to invadosomes. Eur J Cell Biol 2011; 90:376-89. [PMID: 21333378 DOI: 10.1016/j.ejcb.2010.11.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 11/23/2010] [Accepted: 11/24/2010] [Indexed: 11/26/2022] Open
Abstract
The actin-filament associated protein (AFAP) family of adaptor proteins consists of three members: AFAP1, AFAP1L1, and AFAP1L2/XB130 with AFAP1 being the best described as a cSrc binding partner and actin cross-linking protein. A homology search of AFAP1 recently identified AFAP1L1 which has a similar sequence, domain structure and cellular localization; however, based upon sequence variations, AFAP1L1 is hypothesized to have unique functions that are distinct from AFAP1. While AFAP1 has the ability to bind to the SH3 domain of the nonreceptor tyrosine kinase cSrc via an N-terminal SH3 binding motif, it was unable to bind cortactin. However, the SH3 binding motif of AFAP1L1 was more efficient at interacting with the SH3 domain of cortactin and not cSrc. AFAP1L1 was shown by fluorescence microscopy to decorate actin filaments and move to punctate actin structures and colocalize with cortactin, consistent with localization to invadosomes. Upon overexpression in A7r5 cells, AFAP1L1 had the ability to induce podosome formation and move to podosomes without stimulation. Immunohistochemical analysis of AFAP1L1 in human tissues shows differential expression when contrasted with AFAP1 with localization of AFAP1L1 to unique sites in muscle and the dentate nucleus of the brain where AFAP1 was not detectable. We hypothesize AFAP1L1 may play a similar role to AFAP1 in affecting changes in actin filaments and bridging interactions with binding partners, but we hypothesize that AFAP1L1 may forge unique protein interactions in which AFAP1 is less efficient, and these interactions may allow AFAP1L1 to affect invadosome formation.
Collapse
Affiliation(s)
- Brandi N Snyder
- The Mary Babb Randolph Cancer Center and the Department of Cancer Cell Biology, West Virginia University, Morgantown, WV 26505, USA
| | | | | | | | | | | |
Collapse
|
11
|
Yadav SS, Miller WT. The evolutionarily conserved arrangement of domains in SRC family kinases is important for substrate recognition. Biochemistry 2008; 47:10871-80. [PMID: 18803405 DOI: 10.1021/bi800930e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The SH3-SH2-kinase domain arrangement in nonreceptor tyrosine kinases has been conserved throughout evolution. For Src family kinases, the relative positions of the domains are important for enzyme regulation; they permit the assembly of Src kinases into autoinhibited conformations. The SH3 and SH2 domains of Src family kinases have an additional role in determining the substrate specificity of the kinase. We addressed the question of whether the domain arrangement of Src family kinases has a role in substrate specificity by producing mutants with alternative arrangements. Our results suggest that changes in the positions of domains can lead to specific changes in the phosphorylation of Sam68 and Cas by Src. Phosphorylation of Cas by several mutants triggers downstream signaling leading to cell migration. The placement of the SH2 domain with respect to the catalytic domain of Src appears to be especially important for proper substrate recognition, while the placement of the SH3 domain is more flexible. The results suggest that the involvement of the SH3 and SH2 domains in substrate recognition is one reason for the strict conservation of the SH3-SH2-kinase architecture.
Collapse
Affiliation(s)
- Shalini S Yadav
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, New York 11794-8661, USA
| | | |
Collapse
|
12
|
Solheim SA, Petsalaki E, Stokka AJ, Russell RB, Taskén K, Berge T. Interactions between the Fyn SH3-domain and adaptor protein Cbp/PAG derived ligands, effects on kinase activity and affinity. FEBS J 2008; 275:4863-74. [PMID: 18721137 DOI: 10.1111/j.1742-4658.2008.06626.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Csk-binding protein/phosphoprotein associated with glycosphingolipid-enriched domains is a transmembrane adaptor protein primarily involved in negative regulation of T-cell activation by recruitment of C-terminal Src kinase (Csk), a protein tyrosine kinase which represses Src kinase activity through C-terminal phosphorylation. Recruitment of Csk occurs via SH2-domain binding to PAG pTyr317, thus, the interaction is highly dependent on phosphorylation performed by the Src family kinase Fyn, which docks onto PAG using a dual-domain binding mode involving both SH3- and SH2-domains of Fyn. In this study, we investigated Fyn SH3-domain binding to 14-mer peptide ligands derived from Cbp/PAG-enriched microdomains sequence using biochemical, biophysical and computational techniques. Interaction kinetics and dissociation constants for the various ligands were determined by SPR. The local structural impact of ligand association has been evaluated using CD, and molecular modelling has been employed to investigate details of the interactions. We show that data from these investigations correlate with functional effects of ligand binding, assessed experimentally by kinase assays using full-length PAG proteins as substrates. The presented data demonstrate a potential method for modulation of Src family kinase tyrosine phosphorylation through minor changes of the substrate SH3-interacting motif.
Collapse
Affiliation(s)
- Silje A Solheim
- The Biotechnology Centre of Oslo, University of Oslo, Norway
| | | | | | | | | | | |
Collapse
|
13
|
The actin cross-linking protein AFAP120 regulates axon elongation in a tyrosine phosphorylation-dependent manner. Neurosci Lett 2008; 444:132-6. [PMID: 18723076 DOI: 10.1016/j.neulet.2008.08.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 06/30/2008] [Accepted: 08/04/2008] [Indexed: 01/30/2023]
Abstract
Growth cone guidance and axon elongation require the dynamic coordinated regulation of the actin cytoskeleton. As the growth cone moves, actin-dependent forces generate tension that enables protrusive activity in the periphery and drives growth cone translocation. This dynamic remodeling of the actin cytoskeleton in response to membrane tension requires activation of Src kinase. Although it has been proposed that these actin-dependent forces vary with the extent of actin cross-linking, the identity of the cross-linking protein(s) remains unknown. AFAP120 is a nervous system specific actin cross-linking protein that is regulated by Src kinase phosphorylation. Here, we report that AFAP120 is expressed and tyrosine phosphorylated in differentiating cerebellar granule cells, where it is enriched in the axon and growth cone. Over-expression of AFAP120 enhances neurite elongation in a tyrosine phosphorylation-dependent manner. These findings suggest that AFAP120 may coordinate Src signaling with the dynamic changes in the actin cytoskeleton that drive growth cone motility and axon elongation.
Collapse
|
14
|
Dorfleutner A, Cho Y, Vincent D, Cunnick J, Lin H, Weed SA, Stehlik C, Flynn DC. Phosphorylation of AFAP-110 affects podosome lifespan in A7r5 cells. J Cell Sci 2008; 121:2394-405. [PMID: 18577577 DOI: 10.1242/jcs.026187] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
AFAP-110 is an actin-binding and -crosslinking protein that is enriched in Src and phorbol ester (PE)-induced podosomes. In vascular smooth muscle cells endogenous AFAP-110 localized to actin stress fibers and, in response to treatment with phorbol-12,13-dibutyrate (PDBu), to actin-rich podosomes. Since PEs can activate PKCalpha, AFAP-110 is a substrate of PKCalpha and PKCalpha-AFAP-110 interactions direct podosome formation, we sought to identify a PE-induced phosphorylation site in AFAP-110 and determine whether phosphorylation is linked to the formation of podosomes. Mutational analysis revealed Ser277 of AFAP-110 to be phosphorylated in PE-treated cells. The use of a newly generated, phospho-specific antibody directed against phosphorylated Ser277 revealed that PKCalpha activation is associated with PE-induced AFAP-110 phosphorylation. In PDBu-treated A7r5 rat vascular smooth muscle cells, immunolabeling using the phospho-specific antibody showed that phospho-AFAP-110 is primarily associated with actin in podosomes. Although mutation of Ser at position 277 to Ala (AFAP-110(S277A)) did not alter the ability of AFAP-110 to localize to podosomes, overexpression of AFAP-110(S277A) in treated and untreated A7r5 cells resulted in an increased number of cells that display podosomes. Video microscopy demonstrated that AFAP-110(S277A) expression correlates with an increased number of long-lived podosomes. Therefore, we hypothesize that AFAP-110 phosphorylation and/or dephosphorylation is involved in the regulation of podosome stability and lifespan.
Collapse
Affiliation(s)
- Andrea Dorfleutner
- The Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, WV 26506-9300, USA
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Solheim SA, Torgersen KM, Taskén K, Berge T. Regulation of FynT Function by Dual Domain Docking on PAG/Cbp. J Biol Chem 2008; 283:2773-83. [DOI: 10.1074/jbc.m705215200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
|
16
|
Dorfleutner A, Stehlik C, Zhang J, Gallick GE, Flynn DC. AFAP-110 is required for actin stress fiber formation and cell adhesion in MDA-MB-231 breast cancer cells. J Cell Physiol 2007; 213:740-9. [PMID: 17520695 DOI: 10.1002/jcp.21143] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Regulation of actin organization and dynamics is a highly complex process that involves a number of actin-binding proteins, including capping, branching, severing, sequestering, and cross-linking proteins. The actin-binding and cross-linking protein AFAP-110 is expressed in normal myoepithelial cells. Screening of different breast epithelial cell lines revealed high expression levels of AFAP-110 in the human breast cancer cell lines MDA-MB-231 and MDA-MB-435. Knockdown of AFAP-110 expression in MDA-MB-231 cells does not result in any changes in cell proliferation but did result in a loss of actin stress fiber cross-linking and decreased adhesion to fibronectin. An inducible knockdown approach confirms that MDA-MB-231 breast cancer cells require AFAP-110 expression for stress fiber formation and adhesion. Thus, AFAP-110 may provide cytoskeletal tension through stress fiber formation, which is required for focal adhesion formation. Indeed, we could not detect any focal contacts or focal adhesions in AFAP-110 knockdown cells after adhesion to fibronectin. Although expression levels of crucial focal adhesion components were not influenced by AFAP-110 expression levels, treatment of AFAP-110 knockdown cells with LPA did not result in induction of actin stress fibers and focal adhesions. In summary, AFAP-110 plays an important role in MDA-MB-231 breast cancer cell adhesion possibly by regulating stress filament cross-linking which would promote focal adhesion formation.
Collapse
Affiliation(s)
- Andrea Dorfleutner
- The Mary Babb Randolph Cancer Center and the Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, West Virginia 26505-9300, USA
| | | | | | | | | |
Collapse
|
17
|
Zhang J, Park SI, Artime MC, Summy JM, Shah AN, Bomser JA, Dorfleutner A, Flynn DC, Gallick GE. AFAP-110 is overexpressed in prostate cancer and contributes to tumorigenic growth by regulating focal contacts. J Clin Invest 2007; 117:2962-73. [PMID: 17885682 PMCID: PMC1978423 DOI: 10.1172/jci30710] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Accepted: 07/09/2007] [Indexed: 01/07/2023] Open
Abstract
The actin filament-associated protein AFAP-110 is an actin cross-linking protein first identified as a substrate of the viral oncogene v-Src. AFAP-110 regulates actin cytoskeleton integrity but also functions as an adaptor protein that affects crosstalk between Src and PKC. Here we investigated the roles of AFAP-110 in the tumorigenic process of prostate carcinoma. Using immunohistochemistry of human tissue arrays, we found that AFAP-110 was absent or expressed at very low levels in normal prostatic epithelium and benign prostatic hyperplasia but significantly increased in prostate carcinomas. The level of AFAP-110 in carcinomas correlated with the Gleason scores. Downregulation of AFAP-110 in PC3 prostate cancer cells inhibited cell proliferation in vitro and tumorigenicity and growth in orthotopic nude mouse models. Furthermore, downmodulation of AFAP-110 resulted in decreased cell-matrix adhesion and cell migration, defective focal adhesions, and reduced integrin beta1 expression. Reintroduction of avian AFAP-110 or a mutant disabling its interaction with Src restored these properties. However, expression of an AFAP-110 lacking the PKC-interacting domain failed to restore properties of parental cells. Thus, increased expression of AFAP-110 is associated with progressive stages of prostate cancer and is critical for tumorigenic growth, in part by regulating focal contacts in a PKC-dependent mechanism.
Collapse
Affiliation(s)
- Jing Zhang
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| | - Serk In Park
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| | - Marlene C. Artime
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| | - Justin M. Summy
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| | - Ami N. Shah
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| | - Joshua A. Bomser
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| | - Andrea Dorfleutner
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| | - Daniel C. Flynn
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| | - Gary E. Gallick
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, USA.
Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Human Nutrition, The Ohio State University, Columbus, Ohio, USA.
Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, West Virginia, USA
| |
Collapse
|
18
|
Walker VG, Ammer A, Cao Z, Clump AC, Jiang BH, Kelley LC, Weed SA, Zot H, Flynn DC. PI3K activation is required for PMA-directed activation of cSrc by AFAP-110. Am J Physiol Cell Physiol 2007; 293:C119-32. [PMID: 17360811 DOI: 10.1152/ajpcell.00525.2006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activation of PKCalpha will induce the cSrc binding partner AFAP-110 to colocalize with and activate cSrc. The ability of AFAP-110 to colocalize with cSrc is contingent on the integrity of the amino-terminal pleckstrin homology (PH1) domain, while the ability to activate cSrc is dependent on the integrity of its SH3 binding motif, which engages the cSrc SH3 domain. The outcome of AFAP-110-directed cSrc activation is a change in actin filament integrity and the formation of podosomes. Here, we address what cellular signals promote AFAP-110 to colocalize with and activate cSrc, in response to PKCalpha activation or PMA treatment. Because PH domain integrity in AFAP-110 is required for colocalization, and PH domains are known to interact with both protein and lipid binding partners, we sought to determine whether phosphatidylinositol 3-kinase (PI3K) activation played a role in PMA-induced colocalization between AFAP-110 and cSrc. We show that PMA treatment is able to direct activation of PI3K. Treatment of mouse embryo fibroblast with PI3K inhibitors blocked PMA-directed colocalization between AFAP-110 and cSrc and subsequent cSrc activation. PMA also was unable to induce colocalization or cSrc activation in cells that lacked the p85alpha and -beta regulatory subunits of PI3K. This signaling pathway was required for migration in a wound healing assay. Cells that were null for cSrc or the p85 regulatory subunits or expressed a dominant-negative AFAP-110 also displayed a reduction in migration. Thus PI3K activity is required for PMA-induced colocalization between AFAP-110 and cSrc and subsequent cSrc activation, and this signaling pathway promotes cell migration.
Collapse
Affiliation(s)
- Valerie G Walker
- The Mary Babb Randolph Cancer Center, Dept. of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, WV 26506-9300, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Zellefrow CD, Griffiths JS, Saha S, Hodges AM, Goodman JL, Paulk J, Kritzer JA, Schepartz A. Encodable Activators of Src Family Kinases. J Am Chem Soc 2006; 128:16506-7. [PMID: 17177392 DOI: 10.1021/ja0672977] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
There is considerable current interest in the design of encodable molecules that regulate intracellular protein circuitry and/or activity, ideally with a high level of specificity. Src homology 3 (SH3) domains are ubiquitous components of multidomain signaling proteins, including many kinases, and are attractive drug targets because of the important role their interactions play in diseases as diverse as cancer, osteoporosis, and inflammation. Here we describe a set of miniature proteins that recognize distinct SH3 domains from Src family kinases with high affinity. Three of these molecules discriminate effectively between the SH3 domains of Src and Fyn, which are expressed ubiquitously, and two of these three activate Hck kinase with potencies that rival HIV Nef, one of the most potent kinase activators known. These results suggest that miniature proteins represent a viable, encodable strategy for selective activation of Src family kinases in a variety of cell types.
Collapse
|
20
|
Abstract
Transmembrane receptors link the extracellular environment to the internal control elements of the cell. This signaling influences cell division, differentiation, survival, motility, adhesion, spreading and vesicular transport. Central to this signaling is the Src family of nonreceptor tyrosine kinases. The most studied kinase of this nine member family, c-Src, shares a similar structure, as well as a similar expression pattern to that of another Src family protein, c-Yes. Despite high conservation in sequence, molecular studies demonstrate that the functional domains of these kinases can contribute to specificity in signaling. At the cellular level, analysis of tight junction formation also serves as a model to differentiate c-Yes and c-Src signaling. Results suggest that c-Yes promotes formation of the tight junction by phosphorylating occludin, while c-Src signaling downregulates occludin formation in a Raf-1 dependent manner. In addition, pp62c-Yes knockout mice exhibit a specific physiological function phenotype that is distinct from c-src-/- mice. In these studies, c-yes-/- mice exhibit decreased transcytosis of pIgA from the blood to the bile, while c-src-/- mice exhibit deficits in osteoclasts function and bone resorption. Of particular interest in this review are receptor signals that specifically influence the actions of c-Yes. Growth factors that influence many Src family proteins include the PDGF-R, CSF-1 receptor and others. Since these receptors interact with various Src-family kinases, it is predicted that specific signaling is generated by differential recruitment to the cell membrane and/or differentiated interactions with substrates and binding partners. This review provides an overview of c-Yes interactions with specific receptor signaling pathways and how this interaction potentially influences the known physiological roles of c-Yes.
Collapse
Affiliation(s)
- David A Clump
- Department of Microbiology, Immunology, and Cell Biology, The Mary Babb Randolph Cancer Center and the West Virginia University, Morgantown, WV 26506-9300, USA
| | | | | | | |
Collapse
|
21
|
Yokoyama N, deBakker CD, Zappacosta F, Huddleston MJ, Annan RS, Ravichandran KS, Miller WT. Identification of tyrosine residues on ELMO1 that are phosphorylated by the Src-family kinase Hck. Biochemistry 2005; 44:8841-9. [PMID: 15952790 PMCID: PMC2441568 DOI: 10.1021/bi0500832] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The SH3 and SH2 domains of hematopoietic cell kinase (Hck) play important roles in substrate targeting. To identify new components of Hck signaling pathways, we identified proteins that bind to the SH3 domain of Hck (Scott et al. (2002) J. Biol. Chem. 277, 28238). One such protein was ELMO1, the mammalian orthologue of the Caenorhabditis elegans gene, ced-12. ELMO1 is an approximately 80-kD protein containing a PH domain and a C-terminal Pro-rich sequence. In C. elegans, ced-12 is required for the engulfment of dying cells and for cell migration. In mammalian fibroblasts, ELMO1 binds to Dock180, and functions upstream of Rac during phagocytosis and cell migration. We previously showed that ELMO1 binds directly to the Hck SH3 domain and is phosphorylated by Hck. In this study, we used mass spectrometry to identify the following sites of ELMO1 phosphorylation: Tyr 18, Tyr 216, Tyr 511, Tyr 395, and Tyr 720. Mutant forms of ELMO1 lacking these sites were defective in their ability to promote phagocytosis and migration in fibroblasts. Single tyrosine mutations showed that Tyr 511 is particularly important in mediating these biological effects. These mutants displayed comparable binding to Dock180 and Crk as wild-type ELMO1, but gave a lowered activation of Rac. The data suggest that Src family kinase mediated tyrosine phosphorylation of ELMO1 might represent an important regulatory mechanism that controls signaling through the ELMO1/Crk/Dock180 pathway.
Collapse
Affiliation(s)
- Noriko Yokoyama
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661
| | - Colin D. deBakker
- Beirne Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia 22908
| | - Francesca Zappacosta
- Proteomics and Biological Mass Spectrometry Laboratory, Department of Computational, Analytical and Structural Sciences, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania 19406
| | - Michael J. Huddleston
- Proteomics and Biological Mass Spectrometry Laboratory, Department of Computational, Analytical and Structural Sciences, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania 19406
| | - Roland S. Annan
- Proteomics and Biological Mass Spectrometry Laboratory, Department of Computational, Analytical and Structural Sciences, GlaxoSmithKline Pharmaceuticals, King of Prussia, Pennsylvania 19406
| | - Kodi S. Ravichandran
- Beirne Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia 22908
| | - W. Todd Miller
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661
- To whom correspondence should be addressed. Mailing address: Dept. of Physiology and Biophysics, Basic Science Tower, T-6, School of Medicine, SUNY at Stony Brook, Stony Brook, NY 11794-8661. Tel: 631-444-3533. Fax: 631-444-3432. E-mail:
| |
Collapse
|
22
|
Gatesman A, Walker VG, Baisden JM, Weed SA, Flynn DC. Protein kinase Calpha activates c-Src and induces podosome formation via AFAP-110. Mol Cell Biol 2004; 24:7578-97. [PMID: 15314167 PMCID: PMC506973 DOI: 10.1128/mcb.24.17.7578-7597.2004] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We report that the actin filament-associated protein AFAP-110 is required to mediate protein kinase Calpha (PKCalpha) activation of the nonreceptor tyrosine kinase c-Src and the subsequent formation of podosomes. Immunofluorescence analysis demonstrated that activation of PKCalpha by phorbol 12-myristate 13-acetate (PMA), or ectopic expression of constitutively activated PKCalpha, directs AFAP-110 to colocalize with and bind to the c-Src SH3 domain, resulting in activation of the tyrosine kinase. Activation of c-Src then directs the formation of podosomes, which contain cortactin, AFAP-110, actin, and c-Src. In a cell line (CaOV3) that has very little or no detectable AFAP-110, PMA treatment was unable to activate c-Src or effect podosome formation. Ectopic expression of AFAP-110 in CaOV3 cells rescued PKCalpha-mediated activation of c-Src and elevated tyrosine phosphorylation levels and subsequent formation of podosomes. Neither expression of activated PKCalpha nor treatment with PMA was able to induce these changes in CAOV3 cells expressing mutant forms of AFAP-110 that are unable to bind to, or colocalize with, c-Src. We hypothesize that one major function of AFAP-110 is to relay signals from PKCalpha that direct the activation of c-Src and the formation of podosomes.
Collapse
Affiliation(s)
- Amanda Gatesman
- The Mary Babb Randolph Cancer Center and Department of Microbiology, Immunology, and Cell Biology, West Virginia University, Morgantown, WV 26506-9300, USA
| | | | | | | | | |
Collapse
|
23
|
Qian Y, Gatesman AS, Baisden JM, Zot HG, Cherezova L, Qazi I, Mazloum N, Lee MY, Guappone-Koay A, Flynn DC. Analysis of the role of the leucine zipper motif in regulating the ability of AFAP-110 to alter actin filament integrity. J Cell Biochem 2004; 91:602-20. [PMID: 14755689 DOI: 10.1002/jcb.10725] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
AFAP-110 has an intrinsic ability to alter actin filament integrity as an actin filament crosslinking protein. This capability is regulated by a carboxy terminal leucine zipper (Lzip) motif. The Lzip motif facilitates self-association stabilizing the AFAP-110 multimers. Deletion of the Lzip motif (AFAP-110(Deltalzip)) reduces the stability of the AFAP-110 multimer and concomitantly increases its ability to crosslink actin filaments, in vitro, and to activate cSrc and alter actin filament integrity, in vivo. We sought to determine how the Lzip motif regulates AFAP-110 function. Substitution of the c-Fos Lzip motif in place of the AFAP-110 Lzip motif (AFAP-110(fos)) was predicted to preserve the alpha-helical structure while changing the sequence. To alter the structure of the alpha-helix, a leucine to proline mutation was generated in the AFAP-110 alpha-helical Lzip motif (AFAP-110(581P)), which largely preserved the sequence. The helix mutants, AFAP-110(Deltalzip), AFAP-110(fos), and AFAP-110(581P), demonstrated reduced multimer stability with an increased capacity to crosslink actin filaments, in vitro, relative to AFAP-110. An analysis of opposing binding sites indicated that the carboxy terminus/Lzip motif can contact sequences within the amino terminal pleckstrin homology (PH1) domain indicating an auto-inhibitory mechanism for regulating multimer stability and actin filament crosslinking. In vivo, only AFAP-110(Deltalzip) and AFAP-110(581P) were to activate cSrc and to alter cellular actin filament integrity. These data indicate that the intrinsic ability of AFAP-110 to crosslink actin filaments is dependent upon both the sequence and structure of the Lzip motif, while the ability of the Lzip motif to regulate AFAP-110-directed activation of cSrc and changes in actin filament integrity in vivo is dependent upon the structure or presence of the Lzip motif. We hypothesize that the intrinsic ability of AFAP-110 to crosslink actin filaments or activate cSrc are distinct functions.
Collapse
MESH Headings
- Actin Cytoskeleton/physiology
- Animals
- Blotting, Western
- COS Cells
- Chlorocebus aethiops
- Chromatography, Liquid
- Cloning, Molecular
- Gene Components/genetics
- Gene Components/physiology
- Genes, fos/genetics
- Glutathione Transferase/genetics
- Glutathione Transferase/metabolism
- Green Fluorescent Proteins
- Leucine Zippers/genetics
- Leucine Zippers/physiology
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Microfilament Proteins/chemistry
- Microfilament Proteins/genetics
- Microfilament Proteins/physiology
- Microscopy, Electron
- Microscopy, Fluorescence
- Models, Biological
- Mutagenesis, Site-Directed
- Phosphoproteins/chemistry
- Phosphoproteins/genetics
- Phosphoproteins/physiology
- Protein Binding/physiology
- Protein Structure, Quaternary
- Protein Structure, Secondary
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- src-Family Kinases/metabolism
Collapse
Affiliation(s)
- Yong Qian
- The Mary Babb Randolph Cancer Center and the Department of Microbiology and Immunology, West Virginia University, Morgantown, West Virginia 26506-9300, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Abstract
Cytoplasmic tyrosine kinases do not occur as isolated catalytic domains. Instead, each kinase family possesses a characteristic array of additional domains that are appended to the catalytic domain. The combination and the arrangement of these modular domains are important in kinase regulation and function. This Account describes how the noncatalytic regions of Src family tyrosine kinases are involved in enzyme regulation, substrate selection, and multisite phosphorylation.
Collapse
|
25
|
Clump DA, Clem R, Qian Y, Guappone-Koay A, Berrebi AS, Flynn DC. Protein expression levels of the Src activating protein AFAP are developmentally regulated in brain. JOURNAL OF NEUROBIOLOGY 2003; 54:473-85. [PMID: 12532398 DOI: 10.1002/neu.10143] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The Src family of nonreceptor tyrosine kinases plays an important role in modulating signals that affect growth cone extension, neuronal differentiation, and brain development. Recent reports indicate that the Src SH2/SH3 binding partner AFAP-110 has the capacity to modulate actin filament integrity as a cSrc activating protein and as an actin filament bundling protein. Both AFAP-110 and a brain specific isoform called AFAP-120 (collectively referred to as AFAP) exist at high levels in chick embryo brain. We sought to identify the localization of AFAP in mouse brain in order to identify its expression pattern and potential role as a cellular modulator of Src family kinase activity and actin filament integrity in the brain. In E16 mouse embryos, AFAP expression levels were very high and concentrated in the olfactory bulb, cortex, forebrain, cerebellum, and various peripheral sensory structures. In P3 mouse pups, overall expression was reduced compared to E16 embryos, and AFAP was found primarily in olfactory bulb, cortex, and cerebellum. AFAP expression levels were significantly reduced in adult mice, with high expression levels only detected in the olfactory bulb. Western blot analysis indicated that concentrated expression of AFAP correlates well with the AFAP-120 isoform, which appears to be a splice variant of AFAP-110. As the expression pattern of AFAP overlaps with the reported expression patterns of cSrc and Fyn, we hypothesize that AFAP is positioned to modulate signal transduction cascades that direct activation of these nonreceptor tyrosine kinases and concomitant cellular changes that occur in actin filaments during brain development.
Collapse
Affiliation(s)
- David A Clump
- The Mary Babb Randolph Cancer Center and the Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, West Virginia 26506-9300, USA
| | | | | | | | | | | |
Collapse
|
26
|
Scott MP, Zappacosta F, Kim EY, Annan RS, Miller WT. Identification of novel SH3 domain ligands for the Src family kinase Hck. Wiskott-Aldrich syndrome protein (WASP), WASP-interacting protein (WIP), and ELMO1. J Biol Chem 2002; 277:28238-46. [PMID: 12029088 DOI: 10.1074/jbc.m202783200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The importance of the SH3 domain of Hck in kinase regulation, substrate phosphorylation, and ligand binding has been established. However, few in vivo ligands are known for the SH3 domain of Hck. In this study, we used mass spectrometry to identify approximately 25 potential binding partners for the SH3 domain of Hck from the monocyte cell line U937. Two major interacting proteins were the actin binding proteins Wiskott-Aldrich syndrome protein (WASP) and WASP-interacting protein (WIP). We also focused on a novel interaction between Hck and ELMO1, an 84-kDa protein that was recently identified as the mammalian ortholog of the Caenorhabditis elegans gene, ced-12. In mammalian cells, ELMO1 interacts with Dock180 as a component of the CrkII/Dock180/Rac pathway responsible for phagocytosis and cell migration. Using purified proteins, we confirmed that WASP-interacting protein and ELMO1 interact directly with the SH3 domain of Hck. We also show that Hck and ELMO1 interact in intact cells and that ELMO1 is heavily tyrosine-phosphorylated in cells that co-express Hck, suggesting that it is a substrate of Hck. The binding of ELMO1 to Hck is specifically dependent on the interaction of a polyproline motif with the SH3 domain of Hck. Our results suggest that these proteins may be novel activators/effectors of Hck.
Collapse
Affiliation(s)
- Margaret Porter Scott
- Department of Physiology and Biophysics, School of Medicine, State University of New York, Stony Brook, New York 11794-8661, USA
| | | | | | | | | |
Collapse
|
27
|
Lodyga M, Bai XH, Mourgeon E, Han B, Keshavjee S, Liu M. Molecular cloning of actin filament-associated protein: a putative adaptor in stretch-induced Src activation. Am J Physiol Lung Cell Mol Physiol 2002; 283:L265-74. [PMID: 12114187 DOI: 10.1152/ajplung.00492.2001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical stretch-induced activation of c-Src is an important step for signal transduction of stretch-induced fetal rat lung cell proliferation. This process appears to be mediated through actin filament-associated protein (AFAP), encoded by a gene originally cloned from the chicken. In the present study, we cloned the rat AFAP gene from fetal rat lungs. Its mRNA and protein are differentially expressed among various tissues. The protein is colocalized with actin filaments in fetal rat lung epithelial cells and fibroblasts. Mechanical stretch increased tyrosine phosphorylation of rat AFAP and its binding to c-Src within the initial several minutes. Src SH2 and SH3 binding motifs are highly conserved in the AFAP proteins (from chicken, rat to human). On the basis of the molecular structure of AFAP protein, we speculate that it is an adaptor in mechanical stretch-induced activation of c-Src. A novel model of mechanoreception is proposed.
Collapse
Affiliation(s)
- Monika Lodyga
- Thoracic Surgery Research Laboratory, Division of Cellular and Molecular Biology, University Health Network Toronto General Research Institute and Department of Surgery, University of Toronto, Toronto, Ontario, Canada M5G 2C4
| | | | | | | | | | | |
Collapse
|
28
|
Qian Y, Baisden JM, Cherezova L, Summy JM, Guappone-Koay A, Shi X, Mast T, Pustula J, Zot HG, Mazloum N, Lee MY, Flynn DC. PC phosphorylation increases the ability of AFAP-110 to cross-link actin filaments. Mol Biol Cell 2002; 13:2311-22. [PMID: 12134071 PMCID: PMC117315 DOI: 10.1091/mbc.e01-12-0148] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2001] [Revised: 04/02/2002] [Accepted: 04/12/2002] [Indexed: 11/11/2022] Open
Abstract
The actin filament-associated protein and Src-binding partner, AFAP-110, is an adaptor protein that links signaling molecules to actin filaments. AFAP-110 binds actin filaments directly and multimerizes through a leucine zipper motif. Cellular signals downstream of Src(527F) can regulate multimerization. Here, we determined recombinant AFAP-110 (rAFAP-110)-bound actin filaments cooperatively, through a lateral association. We demonstrate rAFAP-110 has the capability to cross-link actin filaments, and this ability is dependent on the integrity of the carboxy terminal actin binding domain. Deletion of the leucine zipper motif or PKC phosphorylation affected AFAP-110's conformation, which correlated with changes in multimerization and increased the capability of rAFAP-110 to cross-link actin filaments. AFAP-110 is both a substrate and binding partner of PKC. On PKC activation, stress filament organization is lost, motility structures form, and AFAP-110 colocalizes strongly with motility structures. Expression of a deletion mutant of AFAP-110 that is unable to bind PKC blocked the effect of PMA on actin filaments. We hypothesize that upon PKC activation, AFAP-110 can be cooperatively recruited to newly forming actin filaments, like those that exist in cell motility structures, and that PKC phosphorylation effects a conformational change that may enable AFAP-110 to promote actin filament cross-linking at the cell membrane.
Collapse
Affiliation(s)
- Yong Qian
- The Mary Babb Randolph Cancer Center and the Department of Microbiology and Immunology, West Virginia University, Morgantown, West Virginia 26506-9300, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Gingras MC, Champagne C, Roy M, Lavoie JN. Cytoplasmic death signal triggered by SRC-mediated phosphorylation of the adenovirus E4orf4 protein. Mol Cell Biol 2002; 22:41-56. [PMID: 11739721 PMCID: PMC134208 DOI: 10.1128/mcb.22.1.41-56.2002] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In transformed cells, the adenovirus E4orf4 death factor works in part by inducing a Src-mediated cytoplasmic apoptotic signal leading to caspase-independent membrane blebbing and cell death. Here we show that Src-family kinases modulate E4orf4 phosphorylation on tyrosine residues. Mutation of tyrosines 26, 42, and 59 to phenylalanines inhibited Src-induced phosphorylation of E4orf4 in vivo and in vitro but had no effect on the molecular association of E4orf4 with Src. However, in contrast to wild-type E4orf4, the nonphosphorylatable E4orf4 mutant was unable to modulate Src-dependent phosphorylation and was deficient in recruiting a subset of tyrosine-phosphorylated proteins. Indeed, the Src substrates cortactin and p62dok were found to associate with wild-type E4orf4 but not with the nonphosphorylatable E4orf4. Importantly, the nonphosphorylatable mutant E4orf4 was preferentially distributed in the cell nucleus, was unable to induce membrane blebbing, and had a highly impaired killing activity. Conversely, an activated form of E4orf4 was obtained by mutation of tyrosine 42 to glutamic acid. This pseudophosphorylated mutant E4orf4 was enriched in the cytoplasm and plasma membrane, showed increased binding to phosphotyrosine-containing proteins, and induced a dramatic blebbing phenotype associated with increased cell death. Altogether, our findings strongly suggest that Src-mediated phosphorylation of adenovirus type 2 E4orf4 is critical to promoting its cytoplasmic and membrane localization and is required for the transduction of E4orf4-Src-dependent induction of membrane blebbing. We propose that E4orf4 acts in part by uncoupling Src-dependent signals to drive the formation of a signaling complex that triggers a cytoplasmic death signal.
Collapse
Affiliation(s)
- Marie-Claude Gingras
- Centre de Recherche en Cancérologie de l'Université Laval, L'Hôtel-Dieu de Québec, CHUQ, Québec, G1R 2J6, Canada
| | | | | | | |
Collapse
|
30
|
Baisden JM, Gatesman AS, Cherezova L, Jiang BH, Flynn DC. The intrinsic ability of AFAP-110 to alter actin filament integrity is linked with its ability to also activate cellular tyrosine kinases. Oncogene 2001; 20:6607-16. [PMID: 11641786 DOI: 10.1038/sj.onc.1204802] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2001] [Revised: 06/26/2001] [Accepted: 07/05/2001] [Indexed: 11/09/2022]
Abstract
The actin filament-associated protein of 110 kDa (AFAP-110) is a Src binding partner that represents a potential modulator of actin filament integrity in response to cellular signals. Previous reports have demonstrated that AFAP-110 is capable of directly binding and altering actin filaments. Deletion of the leucine zipper motif of AFAP-110 (AFAP-110(Deltalzip)) has been shown to induce a phenotype which resembles Src-transformed cells, by repositioning actin filaments into rosettes. This deletion also mimics a conformational change in AFAP-110 that is detected in Src-transformed cells. The results presented here indicate that unlike AFAP-110, AFAP-110(Deltalzip) is capable of activating cellular tyrosine kinases, including Src family members, and that AFAP-110(Deltalzip) itself is hyperphosphorylated. The newly tyrosine phosphorylated proteins and activated Src-family members appear to be associated with actin-rich lamellipodia. A point mutation that alters the SH3-binding motif of AFAP-110(Deltalzip) prevents it from activating tyrosine kinases and altering actin filament integrity. In addition, a deletion within a pleckstrin homology (PH) domain of AFAP-110(Deltalzip) will also revert its effects upon actin filaments. Lastly, dominant-positive RhoA(V14) will block the ability of AFAP-110(Deltalzip) from inducing actin filament rosettes, but does not inhibit Src activation. Thus, conformational changes in AFAP-110 enable it to activate cellular kinases in a mechanism requiring SH3 and/or PH domain interactions. We hypothesize that cellular signals which alter AFAP-110 conformation, enable it to activate cellular kinases such as cSrc, which then direct changes in actin filament integrity in a Rho-dependent fashion.
Collapse
Affiliation(s)
- J M Baisden
- 2822 MBRCC, Department of Microbiology & Immunology, West Virginia University, Morgantown, WV 26506-9300, USA
| | | | | | | | | |
Collapse
|
31
|
Baisden JM, Qian Y, Zot HM, Flynn DC. The actin filament-associated protein AFAP-110 is an adaptor protein that modulates changes in actin filament integrity. Oncogene 2001; 20:6435-47. [PMID: 11607843 DOI: 10.1038/sj.onc.1204784] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The actin filament-associated protein of 110 kDa (AFAP-110) was first identified as an SH3/SH2 binding partner for the nonreceptor tyrosine kinase, Src. Subsequent data have demonstrated that AFAP-110 can interact with other Src family members. AFAP-110 contains additional protein binding modules including two pleckstrin homology domains, a leucine zipper motif and a target sequence for serine/threonine phosphorylation. AFAP-110 interacts with actin filaments directly via a carboxy terminal actin-binding domain. Thus AFAP-110 may function as an adaptor protein by linking Src family members and/or other signaling proteins to actin filaments. AFAP-110 also has an intrinsic capability to alter actin filament integrity that can be revealed upon conformational changes associated with phosphorylation or mutagenesis. Recent data has indicated that AFAP-110 may also serve to activate cSrc in response to this conformational change as well. Thus, AFAP-110 may function in several ways by (1) acting as an adaptor protein that links signaling molecules to actin filaments, (2) serving as a platform for the construction of larger signaling complexes, (3) serving as an activator of Src family kinases in response to cellular signals that alter its conformation and (4) directly effecting actin filament organization as an actin filament cross-linking protein. Here, we will review the structure and function of AFAP-110 as well as potential binding partners and effectors of AFAP-110's ability to alter actin filament integrity.
Collapse
Affiliation(s)
- J M Baisden
- Department Microbiology & Immunology, Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, West Virginia, WV 26506-9300 USA
| | | | | | | |
Collapse
|
32
|
Pellicena P, Miller WT. Processive phosphorylation of p130Cas by Src depends on SH3-polyproline interactions. J Biol Chem 2001; 276:28190-6. [PMID: 11389136 DOI: 10.1074/jbc.m100055200] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many in vivo substrates of Src family tyrosine kinases possess sequences conforming to Src homology 2 and 3 (SH2 and SH3) domain-binding motifs. One such substrate is p130Cas, a protein that is hyperphosphorylated in v-Src transformed cells. Cas contains a substrate domain consisting of 15 potential tyrosine phosphorylation sites, C- and N-terminal polyproline regions fitting the consensus sequence for SH3 domain ligands, and a YDYV motif that binds the Src SH2 domain when phosphorylated. In an effort to understand the mechanisms of processive phosphorylation, we have explored the regions of Cas necessary for interaction with Src using the yeast two-hybrid system. Mutations in the SH2 domain-binding region of Cas or the Src SH2 domain have little effect in Cas-Src complex formation or phosphorylation. However, disruption of the C-terminal polyproline region of Cas completely abolishes interaction between the two proteins and results in impaired phosphorylation of Cas. Kinetic analyses using purified proteins indicated that multisite phosphorylation of Cas by Src follows a processive rather than a distributive mechanism. Furthermore, the kinetic studies show that there are two properties of the polyproline region of Cas that are important in enhancing substrate phosphorylation. First, the C-terminal polyproline serves to activate Src kinases through the process of SH3 domain displacement. Second, this region aids in anchoring the kinase to Cas to facilitate processive phosphorylation of the substrate domain. The two processes combine to ensure phosphorylation of Cas with high efficiency.
Collapse
Affiliation(s)
- P Pellicena
- Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, New York 11794-8661, USA
| | | |
Collapse
|
33
|
Moral Z, Dong K, Wei Y, Sterling H, Deng H, Ali S, Gu R, Huang XY, Hebert SC, Giebisch G, Wang WH. Regulation of ROMK1 channels by protein-tyrosine kinase and -tyrosine phosphatase. J Biol Chem 2001; 276:7156-63. [PMID: 11114300 PMCID: PMC2822675 DOI: 10.1074/jbc.m008671200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have used the two-electrode voltage clamp technique and the patch clamp technique to investigate the regulation of ROMK1 channels by protein-tyrosine phosphatase (PTP) and protein-tyrosine kinase (PTK) in oocytes coexpressing ROMK1 and cSrc. Western blot analysis detected the presence of the endogenous PTP-1D isoform in the oocytes. Addition of phenylarsine oxide (PAO), an inhibitor of PTP, reversibly reduced K(+) current by 55% in oocytes coinjected with ROMK1 and cSrc. In contrast, PAO had no significant effect on K(+) current in oocytes injected with ROMK1 alone. Moreover, application of herbimycin A, an inhibitor of PTK, increased K(+) current by 120% and completely abolished the effect of PAO in oocytes coexpressing ROMK1 and cSrc. The effects of herbimycin A and PAO were absent in oocytes expressing the ROMK1 mutant R1Y337A in which the tyrosine residue at position 337 was mutated to alanine. However, addition of exogenous cSrc had no significant effect on the activity of ROMK1 channels in inside-out patches. Moreover, the effect of PAO was completely abolished by treatment of oocytes with 20% sucrose and 250 microg/ml concanavalin A, agents that inhibit the endocytosis of ROMK1 channels. Furthermore, the effect of herbimycin A is absent in the oocytes pretreated with either colchicine, an inhibitor of microtubules, or taxol, an agent that freezes microtubules. We conclude that PTP and PTK play an important role in regulating ROMK1 channels. Inhibiting PTP increases the internalization of ROMK1 channels, whereas blocking PTK stimulates the insertion of ROMK1 channels.
Collapse
Affiliation(s)
- Zebunnessa Moral
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595
| | - Ke Dong
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510
| | - Yuan Wei
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595
| | - Hyacinth Sterling
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595
| | - Huan Deng
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595
| | - Shariq Ali
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595
| | - RuiMin Gu
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595
| | - Xin-Yun Huang
- Department of Physiology, Cornell University Medical College, New York, New York 10021
| | - Steven C. Hebert
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510
| | - Gerhard Giebisch
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595
| |
Collapse
|
34
|
Hoey JG, Summy J, Flynn DC. Chimeric constructs containing the SH4/Unique domains of cYes can restrict the ability of Src(527F) to upregulate heme oxygenase-1 expression efficiently. Cell Signal 2000; 12:691-701. [PMID: 11080622 DOI: 10.1016/s0898-6568(00)00116-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
cSrc and cYes are the two most homologous members of the Src-family of nonreceptor tyrosine kinases. These kinases perform redundant signalling functions in cells; however, there is also evidence to support specificity in signalling. In this report, specificity in signalling between activated forms of the cSrc and cYes oncoproteins was examined at the level of downstream gene expression. Here, pp60c-src(527F) (Src(527F)) and chimeric constructs of Src(527F) containing combinations of the SH4/Unique/SH3/SH2 domains of cYes were generated to determine whether the individual modular domains of cSrc or cYes could direct distinct cellular signals leading to differential gene expression. A biased, differential display analysis approach was used to analyse changes in gene expression. The data indicate that Src(527F) is capable of upregulating heme oxygenase-1 (HO-1) in CEF cells at the level of transcription and protein expression. Chimeric constructs containing the SH4/Unique domains of cYes were less efficient in upregulating HO-1 expression. Activation of cSrc and expression of the HO-1 gene product are each induced under conditions of hypoxia. We hypothesize that activated cSrc can direct upregulation of HO-1 while activated cYes may be less efficient in stimulating signal transduction pathways that direct expression of HO-1.
Collapse
Affiliation(s)
- J G Hoey
- 2822 MBR Cancer Center, West Virginia University, Morgantown, WV, 26506-9300, USA
| | | | | |
Collapse
|
35
|
Keshavjee S, Zhang XM, Fischer S, Liu M. Ischemia reperfusion-induced dynamic changes of protein tyrosine phosphorylation during human lung transplantation. Transplantation 2000; 70:525-31. [PMID: 10949198 DOI: 10.1097/00007890-200008150-00022] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND We have recently demonstrated that more than 20% of lung cells undergo apoptosis within the first 2 hr of graft reperfusion after human lung transplantation. It has been found that changes of protein tyrosine phosphorylation are involved in the regulation of apoptosis in various cell types. METHODS To determine the protein tyrosine phosphorylation status and related biochemistry changes, lung tissue biopsies were collected from six human lung transplant procedures after cold ischemic preservation (2-5 hr at 4 degrees C), after completing the implantation procedure (approximately 1 hr), and 1 or 2 hr after graft reperfusion. Western blotting was performed to determine protein tyrosine phosphorylation and several signal transduction proteins. Protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) activities were also measured. RESULTS Protein tyrosine phosphorylation was significantly increased after lung implantation and before reperfusion, and significantly decreased during the first 2 hr of graft reperfusion. The activity of Src PTKs was reduced by 50% during graft reperfusion, which was associated with a decrease of Src proteins and human actin filament associated protein, a cofactor for Src activation. PTP activity significantly decreased after lung implantation and remained at a low level 1 hr after reperfusion. After 2 hr of reperfusion, however, PTP activity returned to the basal level. CONCLUSION These dynamic changes of PTK and PTP likely explain the observed alterations of protein tyrosine phosphorylation. The significant decrease in protein tyrosine phosphorylation may be related to the observed apoptotic cell death during human lung transplantation.
Collapse
Affiliation(s)
- S Keshavjee
- Thoracic Surgery Research Laboratory, University Health Network Toronto General Hospital, University of Toronto, Ontario, Canada
| | | | | | | |
Collapse
|
36
|
Wei Y, Bloom P, Gu R, Wang W. Protein-tyrosine phosphatase reduces the number of apical small conductance K+ channels in the rat cortical collecting duct. J Biol Chem 2000; 275:20502-7. [PMID: 10787405 DOI: 10.1074/jbc.m000783200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies have demonstrated that an increase in the activity of protein-tyrosine kinase (PTK) is involved in the down-regulation of the activity of apical small conductance K(+) (SK) channels in the cortical collecting duct (CCD) from rats on a K(+)-deficient diet (). We used the patch clamp technique to investigate the role of protein-tyrosine phosphatase (PTP) in the regulation of the activity of SK channels in the CCD from rats on a high K(+) diet. Western blot analysis indicated that PTP-1D is expressed in the renal cortex. Application of 1 microm phenylarsine oxide (PAO) or 1 mm benzylphosphonic acid, agents that inhibit PTP, reversibly reduced channel activity by 95%. Pretreatment of CCDs with PAO for 30 min decreased the mean NP(o) reversibly from control value 3.20 to 0.40. Addition of 1 microm herbimycin A, an inhibitor of PTK, had no significant effect on channel activity in the CCDs from rats on a high K(+) diet. However, herbimycin A abolished the inhibitory effect of PAO, indicating that the effect of PAO is the result of interaction between PTK and PTP. Addition of brefeldin A, an agent that blocks protein trafficking from Golgi complex to the membrane, had no effect on channel activity. Moreover, application of colchicine, a microtubule inhibitor, or paclitaxel, a microtubule stabilizer, had no effect on channel activity. In contrast, PAO still reduced channel activity in the presence of brefeldin A, colchicine, or paclitaxel. Furthermore, the effect of PAO on channel activity was absent when the tubules were bathed in 16% sucrose-containing bath solution or treated with concanavalin A. We conclude that PTP is involved in the regulation of the activity of SK channels and that inhibition of PTP may facilitate the internalization of the SK channels.
Collapse
Affiliation(s)
- Y Wei
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595, USA
| | | | | | | |
Collapse
|
37
|
Qian Y, Baisden JM, Zot HG, Van Winkle WB, Flynn DC. The carboxy terminus of AFAP-110 modulates direct interactions with actin filaments and regulates its ability to alter actin filament integrity and induce lamellipodia formation. Exp Cell Res 2000; 255:102-13. [PMID: 10666339 DOI: 10.1006/excr.1999.4795] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The actin filament-associated protein AFAP-110 is an SH2/SH3 binding partner for Src. AFAP-110 contains several protein-binding motifs in its amino terminus and has been hypothesized to function as an adaptor molecule that could link signaling proteins to actin filaments. Recent studies using deletional mutagenesis demonstrated that AFAP-110 can alter actin filament integrity in SV40 transformed Cos-1 cells. Thus, AFAP-110 may be positioned to modulate the effects of Src upon actin filaments. In this report, we sought to determine whether (a) AFAP-110 could interact with actin filaments directly and (b) deletion mutants could affect actin filament integrity and cell shape in untransformed fibroblast cells. The data demonstrate that the carboxy terminus of AFAP-110 is both necessary and sufficient for actin filament association, in vivo and in vitro. Analysis of the carboxy terminus revealed a mean 40% similarity with other known actin-binding motifs, indicating a mechanism for binding to actin filaments. AFAP-110 can also induce lamellipodia formation. Contiguous with the alpha-helical, actin-binding motif is an alpha-helical, leucine zipper motif. Deletion of the leucine zipper motif (AFAP(Deltalzip)) followed by cellular expression enabled AFAP(Deltalzip) to alter actin filament integrity and cell shape in untransformed cells as evidenced by the induction of lamellipodia formation. We hypothesize that AFAP-110 may be an important signaling protein that can directly modulate changes in actin filament integrity and induce lamellipodia formation.
Collapse
Affiliation(s)
- Y Qian
- 2822 MBR Cancer Center, West Virginia University, Morgantown, West Virginia 26506-9300, USA
| | | | | | | | | |
Collapse
|
38
|
Porter M, Schindler T, Kuriyan J, Miller WT. Reciprocal regulation of Hck activity by phosphorylation of Tyr(527) and Tyr(416). Effect of introducing a high affinity intramolecular SH2 ligand. J Biol Chem 2000; 275:2721-6. [PMID: 10644735 DOI: 10.1074/jbc.275.4.2721] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Src family tyrosine kinase Hck possesses two phosphorylation sites, Tyr(527) and Tyr(416), that affect the catalytic activity in opposite ways. When phosphorylated, Tyr(527) and residues C-terminal to it are involved in an inhibitory intramolecular interaction with the SH2 domain. However, this sequence does not conform to the sequence of the high affinity SH2 ligand, pYEEI. We mutated this sequence to YEEI and show that this mutant form of Hck cannot be activated by exogenous SH2 ligands. The SH3 domain of Hck is also involved in an inhibitory interaction with the catalytic domain. The SH3 ligand Nef binds to and activates YEEI-Hck mutant in a similar manner to wild-type Hck, indicating that disrupting the SH3 interaction overrides the strengthened SH2 interaction. The other phosphorylation site, Tyr(416), is the autophosphorylation site in the activation loop. Phosphorylation of Tyr(416) is required for Hck activation. We mutated this residue to alanine and characterized its catalytic activity. The Y416A mutant shows a higher K(m) value for peptide and a lower V(max) than autophosphorylated wild-type Hck. We also present evidence for cross-talk between the activation loop and the intramolecular binding of the SH2 and SH3 domains.
Collapse
Affiliation(s)
- M Porter
- Department of Physiology, School of Medicine, State University of New York, Stony Brook, New York 11794-8661, USA
| | | | | | | |
Collapse
|
39
|
Summy JM, Guappone AC, Sudol M, Flynn DC. The SH3 and SH2 domains are capable of directing specificity in protein interactions between the non-receptor tyrosine kinases cSrc and cYes. Oncogene 2000; 19:155-60. [PMID: 10644991 DOI: 10.1038/sj.onc.1203265] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The c-src and c-yes proto-oncogenes encode 60 000 and 62 000 Dalton non-receptor tyrosine kinases of the Src family, pp60c-src and pp62c-yes, respectively. These kinases are over 80% homologous outside of their unique amino termini, yet several studies suggest that differences exist in the regulation, activation, and function of cSrc and cYes. The determinants of specificity in signaling between these proteins, however, remain unclear. In order to investigate the roles of the Src Homology (SH) 3 and 2 domains in mediating signaling specificity between cSrc and cYes, chimeras were created in which the SH3 and/or SH2 domains of cSrc or the fully activated variant Src527F were replaced by the corresponding domains of cYes. These constructs were used to assess the effects of the Yes SH3 and SH2 domains on the ability of Src to form stable complexes with and induce tyrosine phosphorylation of Src SH3 and SH2 domain binding partners in vivo. Both the Yes SH3 and SH2 domains were found to alter the capacity of Src to form stable associations with heterologous proteins. The Yes SH3 domain was unable to affinity absorb the Src SH3/SH2 binding partner AFAP-110 from COS-1 cell lysates, and chimeric constructs of Src527F containing the cYes SH3 domain were unable to efficiently co-immunoprecipitate with AFAP-110 from chicken embryo fibroblasts. Interactions with the Src SH2 domain binding partner pp130cas were unaffected. Additionally, only chimeras containing the cYes SH2 domain were able to co-immunoprecipitate with an unidentified 87 kDa tyrosine-phosphorylated protein. These results indicate that the SH3 and SH2 domains are capable of directing specificity in substrate binding between Src and Yes, suggesting potential mechanisms for generating specificity in signaling between these two highly related non-receptor tyrosine kinases.
Collapse
Affiliation(s)
- J M Summy
- The Mary Babb Randolph Cancer Center, Department of Microbiology, West Virginia University, Morgantown, West Virginia, WV 26506-9300, USA
| | | | | | | |
Collapse
|
40
|
Burnham MR, Harte MT, Bouton AH. The role of SRC-CAS interactions in cellular transformation: ectopic expression of the carboxy terminus of CAS inhibits SRC-CAS interaction but has no effect on cellular transformation. Mol Carcinog 1999; 26:20-31. [PMID: 10487518 DOI: 10.1002/(sici)1098-2744(199909)26:1<20::aid-mc3>3.0.co;2-m] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Several lines of evidence indicate that the adapter molecule p130CAS (crk-associated substrate (CAS)) is required for src-mediated cellular transformation. CAS has been shown to be heavily tyrosine-phosphorylated in src-transformed cells, and genetic variants of src that are deficient in CAS binding are also unable to mediate cellular transformation. In this report, we investigated whether CAS phosphorylation and/or its association with src are required elements of the transformation process. Expression of the carboxy-terminal src binding domain of CAS in Rat 1 fibroblasts expressing a temperature-sensitive allele of v-src inhibited the formation of src-CAS complexes and also inhibited tyrosine phosphorylation of CAS. However, expression of this protein had no effect on morphological transformation, src-mediated actin rearrangements, or anchorage-independent growth of these cells when grown at the src-permissive temperature. Thus, the ability of activated src to mediate cellular transformation is either largely independent of endogenous CAS phosphorylation and/or its association with CAS or, alternatively, the carboxy-terminus of CAS may substitute for endogenous CAS in the process of src-mediated transformation.
Collapse
Affiliation(s)
- M R Burnham
- Department of Microbiology and Cancer Center, University of Virginia Health Science Center, Charlottesville 22908, USA
| | | | | |
Collapse
|
41
|
Abstract
The substrate specificities of protein kinases have been found, in many cases, to be determined at least in part by short regions within the substrate known as docking sites. Docking sites are specific and modular, and can dramatically increase the efficiency of phosphorylation.
Collapse
Affiliation(s)
- P M Holland
- Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington, 98109, USA
| | | |
Collapse
|
42
|
Qian Y, Guappone AC, Baisden JM, Hill MW, Summy JM, Flynn DC. Monoclonal antibodies directed against AFAP-110 recognize species-specific and conserved epitopes. Hybridoma (Larchmt) 1999; 18:167-75. [PMID: 10380016 DOI: 10.1089/hyb.1999.18.167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The actin filament-associated protein, AFAP-110, is a Src SH2/SH3 binding partner that can modulate changes in actin filament structure. AFAP-110 contains a carboxy terminal motif that facilitates actin filament interactions, as well as amino terminal protein binding motifs, including an SH3 binding motif, two SH2 binding motifs, and two Pleckstrin homology domains. Two monoclonal antibodies (MAbs) were developed that recognized epitopes in either the amino terminus (MAb 4C3) or the carboxy terminus (anti-AFAP-110) of AFAP-110. Site-directed mutations that change key proline residues to alanine in the SH3 binding motif and an adjacent proline-rich motif abrogated MAb 4C3 binding. These same mutations have been shown to prevent SH3 interactions between AFAP-110 and Src527F. These data indicate that MAb 4C3 recognizes an epitope that is part of the SH3 binding motif. Interestingly, MAb 4C3 is not efficiently reactive with mammalian homologs of AFAP-110. Sequence analysis of a putative cDNA clone that encodes the amino terminus of the human AFAP-110 isoform predicted a one amino acid difference within this epitope, indicating a mechanism for species-specific binding by MAb 4C3. A second, MAb anti-AFAP-110, recognizes AFAP-110 across species and binds to an epitope within the carboxy terminus. This epitope includes the 5th heptad repeat of the carboxy terminal, leucine zipper motif (amino acids 592-598)--a motif that facilitates self-associations and may regulate the function of AFAP-110. These MAbs will be useful for analyzing the effects of AFAP-110 upon cell morphology and actin filament integrity. In addition, the avian-specific MAb 4C3 may be useful for studying the effects of avian AFAP-110 constructs expressed in mammalian cells, by providing an internal epitope tag.
Collapse
Affiliation(s)
- Y Qian
- Mary Babb Randolph Cancer Center and the Department of Microbiology and Immunology, West Virginia University, Morgantown 26506-9300, USA
| | | | | | | | | | | |
Collapse
|
43
|
Guappone AC, Weimer T, Flynn DC. Formation of a stable src-AFAP-110 complex through either an amino-terminal or a carboxy-terminal SH2-binding motif. Mol Carcinog 1998; 22:110-9. [PMID: 9655255 DOI: 10.1002/(sici)1098-2744(199806)22:2<110::aid-mc6>3.0.co;2-q] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The actin-filament-associated protein (AFAP-1 10) forms a stable complex with activated variants of the Pp60c-src (Src) non-receptor tyrosine kinase through SH2 and SH3 interactions. In this report, site-directed mutagenesis and a transient expression system that permits co-expression of activated pp60c-src (Src527F) and AFAP-110 in Cos-1 cells were used to identify the SH2-binding motif in AFAP-110. Four tyrosine residues, two in the amino terminus (Y93 and Y94) and two in the carboxy terminus (Y451 and Y453), were mutated to phenylalanine, significantly reducing overall steady-state levels of tyrosine phosphorylation and preventing Src527F from forming a stable complex with AFAP-110. These data indicate that the major sites for tyrosine phosphorylation are among these four tyrosine residues and that one or more of these tyrosines may function as an SH2-binding motif. Mutagenesis of just two tyrosines in either the amino terminus (Y93/Y94) or in the carboxy terminus (Y451/Y453) to phenylalanine had only a modest effect on steady-state levels of tyrosine phosphorylation and was not sufficient to abrogate stable-complex formation. These data suggest that Src527F can form a stable complex with AFAP-110 through either of two independently functional SH2-binding motifs. Triple-tyrosine mutation demonstrated that Y93 was not significantly phosphorylated on tyrosine and would not facilitate stable complex formation, whereas Y94, Y451, and Y453 could be phosphorylated on tyrosine and would facilitate stable-complex formation. We hypothesize that Src527F and AFAP-110 interact through a multistep binding mechanism that may either extend interactions between Src527F and actin filaments or permit reorientation of Src527F on AFAP-110, which could facilitate the presentation of Src527F toward other signaling molecules.
Collapse
Affiliation(s)
- A C Guappone
- Mary Babb Randolph Cancer Center and Department of Microbiology and Immunology, West Virginia University, Morgantown 26506-9300, USA
| | | | | |
Collapse
|