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SSeCKS promoted lipopolysaccharide-sensitized astrocytes migration via increasing β-1,4-galactosyltransferase-I activity. Neurochem Res 2019; 44:839-848. [PMID: 30706244 DOI: 10.1007/s11064-019-02716-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 01/02/2019] [Indexed: 12/29/2022]
Abstract
Astrocytes migration is essential in the formation of the glial scar during the injury response process of the central nervous system (CNS) especially during inflammation. Integrin β1 is part of the extracellular matrix receptors in the CNS and it has been reported that integrin β-deficient astrocytes randomly migrate into wounds. Previous studies have found that β-1,4 Galactosyltransferase-I (β-1,4-GalT-I) enhanced the β-1,4-galactosylation of integrin β1. Src-suppressed C kinase substrate (SSeCKS) is an inflammatory response protein which functionally interacts with β-1,4 Galactosyltransferase-I (β-1,4-GalT-I). In this study we aim to investigate the role of SSeCKS and β-1,4-GalT-I in the migration of astrocytes during lipopolysaccharide (LPS)-induced inflammation. Coimmunoprecipitation and immunofluorescence assays have demonstrated that SSeCKS and β-1,4-GalT-I were significantly enhanced in LPS-treated astrocytes and their interactions may occur in the Trans-Golgi Network. Lectin blot showed that the knockdown of β-1,4-GalT-I could inhibit the β-1,4-galactosylation of glycoproteins including integrin β1 with and without LPS, and that SSeCKS knockdown inhibits the β-1,4-galactosylation of glycoproteins including integrin β1 only in LPS-induced astrocytes. Additionally, wound healing assays indicated that β-1,4-GalT-I knockdown could inhibit astrocytes migration with and without LPS but SSeCKS inhibited cell migration only when LPS was present. Therefore our findings suggest that SSeCKS affects astrocytes migration by regulating the β-1,4-galactosylation of glycoproteins including integrin β1, via β-1,4-GalT-I expression in LPS-sensitized astrocytes.
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2
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Wild AR, Dell'Acqua ML. Potential for therapeutic targeting of AKAP signaling complexes in nervous system disorders. Pharmacol Ther 2017; 185:99-121. [PMID: 29262295 DOI: 10.1016/j.pharmthera.2017.12.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A common feature of neurological and neuropsychiatric disorders is a breakdown in the integrity of intracellular signal transduction pathways. Dysregulation of ion channels and receptors in the cell membrane and the enzymatic mediators that link them to intracellular effectors can lead to synaptic dysfunction and neuronal death. However, therapeutic targeting of these ubiquitous signaling elements can lead to off-target side effects due to their widespread expression in multiple systems of the body. A-kinase anchoring proteins (AKAPs) are multivalent scaffolding proteins that compartmentalize a diverse range of receptor and effector proteins to streamline signaling within nanodomain signalosomes. A number of essential neurological processes are known to critically depend on AKAP-directed signaling and an understanding of the role AKAPs play in nervous system disorders has emerged in recent years. Selective targeting of AKAP protein-protein interactions may be a means to uncouple pathologically active signaling pathways in neurological disorders with a greater degree of specificity. In this review we will discuss the role of AKAPs in both regulating normal nervous system function and dysfunction associated with disease, and the potential for therapeutic targeting of AKAP signaling complexes.
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Affiliation(s)
- Angela R Wild
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Mark L Dell'Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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3
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Molyneux K, Wimbury D, Pawluczyk I, Muto M, Bhachu J, Mertens PR, Feehally J, Barratt J. β1,4-galactosyltransferase 1 is a novel receptor for IgA in human mesangial cells. Kidney Int 2017; 92:1458-1468. [PMID: 28750925 DOI: 10.1016/j.kint.2017.05.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 04/23/2017] [Accepted: 05/11/2017] [Indexed: 12/29/2022]
Abstract
IgA nephropathy is characterized by mesangial deposition of IgA, mesangial cell proliferation, and extracellular matrix production. Mesangial cells bind IgA, but the identity of all potential receptors involved remains incomplete. The transferrin receptor (CD71) acts as a mesangial cell IgA receptor and its expression is upregulated in many forms of glomerulonephritis, including IgA nephropathy. CD71 is not expressed in healthy glomeruli and blocking CD71 does not completely abrogate mesangial cell IgA binding. Previously we showed that mesangial cells express a receptor that binds the Fc portion of IgA and now report that this receptor is an isoform of β-1,4-galactosyltransferase. A human mesangial cell cDNA library was screened for IgA binding proteins and β-1,4-galactosyltransferase identified. Cell surface expression of the long isoform of β-1,4-galactosyltransferase was shown by flow cytometry and confocal microscopy and confirmed by immunoblotting. Glomerular β-1,4-galactosyltransferase expression was increased in IgA nephropathy. IgA binding and IgA-induced mesangial cell phosphorylation of spleen tyrosine kinase and IL-6 synthesis were inhibited by a panel of β-1,4-galactosyltransferase-specific antibodies, suggesting IgA binds to the catalytic domain of β-1,4-galactosyltransferase. Thus, β-1,4-galactosyltransferase is a constitutively expressed mesangial cell IgA receptor with an important role in both mesangial IgA clearance and the initial response to IgA deposition.
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Affiliation(s)
- Karen Molyneux
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - David Wimbury
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - Izabella Pawluczyk
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - Masahiro Muto
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - Jasraj Bhachu
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - Peter R Mertens
- Department of Nephrology and Hypertension, Diabetes and Endocrinology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
| | - John Feehally
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | - Jonathan Barratt
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK.
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Elder BH, Shur BD. Mouse fibroblasts null for the long isoform of β1,4-galactosyltransferase-I show defective cell-matrix interactions. Biochem Biophys Res Commun 2016; 478:1248-53. [PMID: 27553271 DOI: 10.1016/j.bbrc.2016.08.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 08/17/2016] [Indexed: 10/21/2022]
Abstract
β1,4 Galactosyltransferase-I (GalT-I) is expressed as two nearly identical polypeptides that differ only in the length of their cytoplasmic domains. The longer isoform has been implicated as a cell surface receptor for extracellular glycoside ligands, such as laminin. To more stringently test the function of the long GalT-I isoform during cell interactions with laminin, we created multiple independent fibroblastic cell lines that fail to express the long isoform, but which express the short GalT-I isoform normally and appear to have normal intracellular galactosylation. Cells devoid of the long GalT-I isoform are unable to adhere and spread on laminin substrates as well as control cells, but retain near normal interactions with fibronectin, which do not rely upon surface GalT-I function. The loss of the long GalT-I isoform also leads to a loss of actin stress fibers, focal adhesions and rac GTPase activation.
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Affiliation(s)
- Brooke H Elder
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Barry D Shur
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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5
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Petrosyan A, Ali MF, Cheng PW. Keratin 1 plays a critical role in golgi localization of core 2 N-acetylglucosaminyltransferase M via interaction with its cytoplasmic tail. J Biol Chem 2015; 290:6256-69. [PMID: 25605727 PMCID: PMC4358263 DOI: 10.1074/jbc.m114.618702] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 01/14/2015] [Indexed: 11/06/2022] Open
Abstract
Core 2 N-acetylglucosaminyltransferase 2/M (C2GnT-M) synthesizes all three β6GlcNAc branch structures found in secreted mucins. Loss of C2GnT-M leads to development of colitis and colon cancer. Recently we have shown that C2GnT-M targets the Golgi at the Giantin site and is recycled by binding to non-muscle myosin IIA, a motor protein, via the cytoplasmic tail (CT). But how this enzyme is retained in the Golgi is not known. Proteomics analysis identifies keratin type II cytoskeletal 1 (KRT1) as a protein pulled down with anti-c-Myc antibody or C2GnT-M CT from the lysate of Panc1 cells expressing bC2GnT-M tagged with c-Myc. Yeast two-hybrid analysis shows that the rod domain of KRT1 interacts directly with the WKR(6) motif in the C2GnT-M CT. Knockdown of KRT1 does not affect Golgi morphology but increases the interaction of C2GnT-M with non-muscle myosin IIA and its transportation to the endoplasmic reticulum, ubiquitination, and degradation. During Golgi recovery after brefeldin A treatment, C2GnT-M forms a complex with Giantin before KRT1, demonstrating CT-mediated sequential events of Golgi targeting and retention of C2GnT-M. In HeLa cells transiently expressing C2GnT-M-GFP, knockdown of KRT1 does not affect Golgi morphology but leaves C2GnT-M outside of the Golgi, resulting in the formation of sialyl-T antigen. Interaction of C2GnT-M and KRT1 was also detected in the goblet cells of human colon epithelial tissue and primary culture of colonic epithelial cells. The results indicate that glycosylation and thus the function of glycoconjugates can be regulated by a protein that helps retain a glycosyltransferase in the Golgi.
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Affiliation(s)
- Armen Petrosyan
- From the VA Nebraska-Western Iowa Health Care System, Department of Research Service, Omaha, Nebraska 68105 and Department of Biochemistry and Molecular Biology, College of Medicine and
| | - Mohamed F Ali
- From the VA Nebraska-Western Iowa Health Care System, Department of Research Service, Omaha, Nebraska 68105 and Department of Biochemistry and Molecular Biology, College of Medicine and
| | - Pi-Wan Cheng
- From the VA Nebraska-Western Iowa Health Care System, Department of Research Service, Omaha, Nebraska 68105 and Department of Biochemistry and Molecular Biology, College of Medicine and Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska 68198
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6
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Expression of SRC suppressed C kinase substrate in rat neural tissues during inflammation. Neurochem Res 2014; 39:748-57. [PMID: 24623461 DOI: 10.1007/s11064-014-1265-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 01/23/2014] [Accepted: 02/24/2014] [Indexed: 01/03/2023]
Abstract
Src-suppressed C kinase substrate (SSeCKS), an in vivo and in vitro protein kinase C substrate, is a major lipopolysaccharide (LPS) response protein which markedly upregulated in several organs, including brain, lung, heart, kidney etc., indicating a possible role of SSeCKS in inflammatory process. However, the expression and biological function of SSeCKS during neuronal inflammation remains to be elucidated, so we established an inflammatory model injected with LPS to investigate the gene expression patterns of SSeCKS in neural tissues by using TaqMan quantitative real-time PCR and immunohistochemistry in rat. Real-time PCR showed that LPS stimulated the expression of SSeCKS mRNA in a dose- and time-dependent manner in sciatic nerves, spinal cords and dorsal root ganglions. Immunohistochemistry showed that SSeCKS colocalized with nerve fibers in sciatic nerve after LPS administration, but there was no colocalization between SSeCKS and Schwann cells. In addition, SSeCKS colocalized with neurons which existed in dorsal root ganglions and spinal cords. These findings indicated that SSeCKS might play some important roles in sciatic nerve fibers and neurons in spinal cords and dorsal root ganglions after LPS injection.
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7
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RNAi screening reveals a large signaling network controlling the Golgi apparatus in human cells. Mol Syst Biol 2013; 8:629. [PMID: 23212246 PMCID: PMC3542528 DOI: 10.1038/msb.2012.59] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 10/11/2012] [Indexed: 12/11/2022] Open
Abstract
RNAi screening and automated image analysis reveal 180 kinases and phosphatases regulating the organization of the Golgi apparatus. Most of these genes also control the expression of specific glycans, pointing to a web of interactions between signaling cascades and glycosylation at the Golgi. ![]()
Golgi organization was probed with three markers of different Golgi compartments and quantitative morphological analysis. Knockdowns of ∼20% of all known kinases and phosphatases affected the Golgi globally or in a compartment-specific manner, and were comparable in degree to the depletion of known membrane traffic regulators such as SNAREs. Several cell surface receptors, their cognate ligands and downstream effectors regulate Golgi organization, suggesting a large regulatory network. Most signaling genes affected both Golgi morphology and the expression of specific glycans.
The Golgi apparatus has many important physiological functions, including sorting of secretory cargo and biosynthesis of complex glycans. These functions depend on the intricate and compartmentalized organization of the Golgi apparatus. To investigate the mechanisms that regulate Golgi architecture, we developed a quantitative morphological assay using three different Golgi compartment markers and quantitative image analysis, and performed a kinome- and phosphatome-wide RNAi screen in HeLa cells. Depletion of 159 signaling genes, nearly 20% of genes assayed, induced strong and varied perturbations in Golgi morphology. Using bioinformatics data, a large regulatory network could be constructed. Specific subnetworks are involved in phosphoinositides regulation, acto-myosin dynamics and mitogen activated protein kinase signaling. Most gene depletion also affected Golgi functions, in particular glycan biosynthesis, suggesting that signaling cascades can control glycosylation directly at the Golgi level. Our results provide a genetic overview of the signaling pathways that control the Golgi apparatus in human cells.
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Petrosyan A, Cheng PW. A non-enzymatic function of Golgi glycosyltransferases: mediation of Golgi fragmentation by interaction with non-muscle myosin IIA. Glycobiology 2013; 23:690-708. [PMID: 23396488 DOI: 10.1093/glycob/cwt009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Golgi apparatus undergoes morphological changes under stress or malignant transformation, but the precise mechanisms are not known. We recently showed that non-muscle myosin IIA (NMIIA) binds to the cytoplasmic tail of Core 2 N-acetylglucosaminyltransferase mucus-type (C2GnT-M) and transports it to the endoplasmic reticulum for recycling. Here, we report that Golgi fragmentation induced by brefeldin A (BFA) or coatomer protein (β-COP) knockdown (KD) in Panc1-bC2GnT-M (c-Myc) cells is accompanied by the increased association of NMIIA with C2GnT-M and its degradation by proteasomes. Golgi fragmentation is prevented by inhibition or KD of NMIIA. Using multiple approaches, we have shown that the speed of BFA-induced Golgi fragmentation is positively correlated with the levels of this enzyme in the Golgi. The observation is reproduced in LNCaP cells which express high levels of two endogenous glycosyltransferases--C2GnT-L and β-galactoside α2,3 sialyltransferase 1. NMIIA is found to form complexes with these two enzymes but not Golgi matrix proteins. The KD of both enzymes or the prevention of Golgi glycosyltransferases from exiting endoplasmic reticulum reduced Golgi-associated NMIIA and decreased the BFA-induced fragmentation. Interestingly, the fragmented Golgi detected in colon cancer HT-29 cells can be restored to a compact morphology after inhibition or KD of NMIIA. The Golgi disorganization induced by the microtubule or actin destructive agent is NMIIA-independent and does not affect the levels of glycosyltransferases. We conclude that NMIIA interacts with Golgi residential but not matrix proteins, and this interaction is responsible for Golgi fragmentation induced by β-COP KD or BFA treatment. This is a novel non-enzymatic function of Golgi glycosyltransferases.
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Affiliation(s)
- Armen Petrosyan
- Department of Research Service, VA Nebraska-Western Iowa Health Care System, Omaha, NE 68105 USA
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9
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Ali MF, Chachadi VB, Petrosyan A, Cheng PW. Golgi phosphoprotein 3 determines cell binding properties under dynamic flow by controlling Golgi localization of core 2 N-acetylglucosaminyltransferase 1. J Biol Chem 2012; 287:39564-77. [PMID: 23027862 DOI: 10.1074/jbc.m112.346528] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Core 2 N-acetylglucosaminyltransferase 1 (C2GnT1) is a key enzyme participating in the synthesis of core 2-associated sialyl Lewis x (C2-O-sLe(x)), a ligand involved in selectin-mediated leukocyte trafficking and cancer metastasis. To accomplish that, C2GnT1 needs to be localized to the Golgi and this step requires interaction of its cytoplasmic tail (CT) with a protein that has not been identified. Employing C2GnT1 CT as the bait to perform a yeast two-hybrid screen, we have identified Golgi phosphoprotein 3 (GOLPH3) as a principal candidate protein that interacts with C2GnT1 and demonstrated that C2GnT1 binds to GOLPH3 via the LLRRR(9) sequence in the CT. Confocal fluorescence microscopic analysis shows substantial Golgi co-localization of C2GnT1 and GOLPH3. Upon GOLPH3 knockdown, C2GnT1 is found mainly in the endoplasmic reticulum and decorated with complex-type N-glycans, indicating that the enzyme has been transported to the Golgi but is not retained. Also, we have found that a recombinant protein consisting of C2GnT1 CT(1-16)-Leu(17-32)-Gly(33-42)-GFP is localized to the Golgi although the same construct with mutated CT (AAAAA(9)) is not. The data demonstrate that the C2GnT1 CT is necessary and sufficient for Golgi localization of C2GnT1. Furthermore, GOLPH3 knockdown results in reduced synthesis of C2-O-sLe(x) associated with P-selectin glycoprotein ligand-1, reduced cell tethering to and rolling on immobilized P- or E-selectin, and compromised E-selectin-induced activation of spleen tyrosine kinase and cell adhesion to intercellular adhesion molecule-1 under dynamic flow. Our results reveal that GOLPH3 can regulate cell-cell interaction by controlling Golgi retention of C2GnT1.
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Affiliation(s)
- Mohamed F Ali
- Department of Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska 68105, USA
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10
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Petrosyan A, Ali MF, Verma SK, Cheng H, Cheng PW. Non-muscle myosin IIA transports a Golgi glycosyltransferase to the endoplasmic reticulum by binding to its cytoplasmic tail. Int J Biochem Cell Biol 2012; 44:1153-65. [PMID: 22525330 PMCID: PMC4011501 DOI: 10.1016/j.biocel.2012.04.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 03/14/2012] [Accepted: 04/04/2012] [Indexed: 12/18/2022]
Abstract
The mechanism of the Golgi-to-ER transport of Golgi glycosyltransferases is not clear. We utilize a cell line expressing the core 2 N-acetylglucosaminyltransferase-M (C2GnT-M) tagged with c-Myc to explore this mechanism. By immunoprecipitation using anti-c-Myc antibodies coupled with proteomics analysis, we have identified several proteins including non-muscle myosin IIA (NMIIA), heat shock protein (HSP)-70 and ubiquitin activating enzyme E1 in the immunoprecipitate. Employing yeast-two-hybrid analysis and pulldown experiments, we show that the C-terminal region of the NMIIA heavy chain binds to the 1-6 amino acids in the cytoplasmic tail of C2GnT-M. We have found that NMIIA co-localizes with C2GnT-M at the periphery of the Golgi. In addition, inhibition or knockdown of NMIIA prevents the brefeldin A-induced collapse of the Golgi as shown by the inhibition of the migration of both Giantin, a Golgi matrix protein, and C2GnT-M, a Golgi non-matrix protein, to the ER. In contrast, knockdown of HSP70 retains Giantin in the Golgi but moves C2GnT-M to the ER, a process also blocked by inhibition or knockdown of NMIIA. Also, the intracellular distribution of C2GnT-M is not affected by knockdown of β-coatomer protein with or without inhibition of HSPs, suggesting that the Golgi-to-ER trafficking of C2GnT-M does not depend on coat protein complex-I. Further, inhibition of proteasome results in accumulation of ubiquitinated C2GnT-M, suggesting its degradation by proteasome. Therefore, NMIIA and not coat protein complex-I is responsible for transporting the Golgi glycosyltransferase to the ER for proteasomal degradation. The data suggest that NMIIA is involved in the Golgi remodeling.
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Affiliation(s)
- Armen Petrosyan
- Omaha Western Iowa Health System, VA Service, Department of Veterans Affairs Medical Center, Omaha, NE, USA
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11
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Yuan Q, Yang H, Cheng C, Li C, Wu X, Huan W, Sun H, Zhou Z, Wang Y, Zhao Y, Lu X, Shen A. β-1,4-Galactosyltransferase I involved in Schwann cells proliferation and apoptosis induced by tumor necrosis factor-alpha via the activation of MAP kinases signal pathways. Mol Cell Biochem 2012; 365:149-58. [PMID: 22359038 DOI: 10.1007/s11010-012-1254-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 02/07/2012] [Indexed: 12/31/2022]
Abstract
β-1,4-galactosyltransferase-I (β-1,4-GalT-I) plays a critical role in the initiation and maintenance of peripheral nervous system inflammatory reaction. However, the exact function of β-1,4-GalT-I in the regulation of SCs proliferation and apoptosis remains unclear. In this study, we found that low concentration of tumor necrosis factor-alpha (TNF-α) induced SCs proliferation, while high concentration of TNF-α induced SCs apoptosis. Meanwhile, the expressions of β-1,4-GalT-I, TNFR1, and TNFR2 were changed following. When β-1,4-GalT I overexpression, low concentration of TNF-α-induced SCs proliferation was partially repressed. Concurrently, the activity of ERK1/2 was decreased. While knocking down β-1,4-GalT I expression, high concentration of TNF-α-induced SCs apoptosis was partially rescued. Consistent with this, the activity of P38 and JNK were decreased. We also found anti-TNFR2 antibody suppressed low concentration of TNF-α-induced SCs proliferation, while anti-TNFR1 antibody inhibited high concentration of TNF-α-induced SCs apoptosis. Thus, present data show that β-1,4-GalT I may play an important role in SCs proliferation and apoptosis induced by TNF-α via different signal pathways and TNFR.
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Affiliation(s)
- Qin Yuan
- Department of Immunology, Medical College, Nantong University, Nantong, Jiangsu 226001, People's Republic of China
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12
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The Relationship Between Src-Suppressed C Kinase Substrate and β-1,4 Galactosyltransferase-I in the Process of Lipopolysaccharide-Induced TNF-α Secretion in Rat Primary Astrocytes. Cell Mol Neurobiol 2011; 31:1047-56. [DOI: 10.1007/s10571-011-9704-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 04/28/2011] [Indexed: 01/03/2023]
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13
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Yang H, Yan M, Cheng C, Jiang J, Zhang L, Liu J, Zhou Z, Shen A. Expression of β-1,4-galactosyltransferase I in rat Schwann cells. J Cell Biochem 2009; 108:75-86. [DOI: 10.1002/jcb.22229] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Yan X, Walkiewicz M, Carlson J, Leiphon L, Grove B. Gravin dynamics regulates the subcellular distribution of PKA. Exp Cell Res 2009; 315:1247-59. [PMID: 19210988 DOI: 10.1016/j.yexcr.2008.12.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 12/24/2008] [Accepted: 12/27/2008] [Indexed: 11/18/2022]
Abstract
Gravin, a multivalent A-kinase anchoring protein (AKAP), localizes to the cell periphery in several cell types and is postulated to target PKA and other binding partners to the plasma membrane. An N-terminal myristoylation sequence and three regions rich in basic amino acids are proposed to mediate this localization. Reports indicating that phorbol ester affects the distribution of SSeCKS, the rat orthologue of gravin, further suggest that PKC may also regulate the subcellular distribution of gravin, which in turn may affect PKA distribution. In this study, quantitative confocal microscopy of cells expressing full-length and mutant gravin-EGFP constructs lacking the proposed targeting domains revealed that either the N-myristoylation site or the polybasic regions were sufficient to target gravin to the cell periphery. Moreover, phorbol ester treatment induced redistribution of gravin-EGFP from the cell periphery to a juxtanuclear vesicular compartment, but this required the presence of the N-myristoylation site. Confocal microscopy further revealed that not only did gravin-EGFP target a PKA RII-ECFP construct to the cell periphery, but PKC activation resulted in redistribution of the gravin and PKA constructs to the same subcellular site. It is postulated that this dynamic response by gravin to PKC activity may mediate PKC dependent control of PKA activity.
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Affiliation(s)
- Xiaohong Yan
- Department of Anatomy and Cell Biology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202-9037, USA
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15
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Yan M, Cheng C, Jiang J, Liu Y, Gao Y, Guo Z, Liu H, Shen A. Essential role of SRC suppressed C kinase substrates in Schwann cells adhesion, spreading and migration. Neurochem Res 2008; 34:1002-10. [PMID: 18979197 DOI: 10.1007/s11064-008-9869-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2008] [Indexed: 11/26/2022]
Abstract
Integrin-mediated substrate adhesion of endothelial cells leads to dynamic rearrangement of the actin cytoskeleton. Protein kinase C (PKC) stimulates reorganization of microfilaments and adhesion, while the responses of Schwann cells during adhesion and migration are unknown, so we examined the expression changes of SSeCKS and F-actin in Schwann cells after exposure to fibronectin. Src (sarcoma) suppressed C kinase substrate (SSeCKS) is a PKC substrate that may play an important role in regulating actin cytoskeleton. We found that SSeCKS was localized to focal adhesion sites soon after Schwann cells adhesion and that SSeCKS increased during the process of cell spreading. Using small interfering RNAs specific to SSeCKS, we showed that Schwann cells in which SSeCKS expression was inhibited reduced cellular adhesion, spreading and promoted cellular migration on fibronectin through reorganization of actin stress fibers and blocking formation of focal adhesions. These results demonstrated SSeCKS modulate Schwann cells adhesion, spreading and migration by reorganization of the actin cytoskeleton.
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Affiliation(s)
- Meijuan Yan
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, People's Republic of China.
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16
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Weiser DC, St Julien KR, Lang JS, Kimelman D. Cell shape regulation by Gravin requires N-terminal membrane effector domains. Biochem Biophys Res Commun 2008; 375:512-516. [PMID: 18725198 DOI: 10.1016/j.bbrc.2008.08.063] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 08/05/2008] [Indexed: 12/11/2022]
Abstract
Gravin (AKAP12, SSeCKS) is a scaffolding protein that acts as a potent inhibitor of tumor metastasis in vivo and in vitro, and regulates morphogenesis during vertebrate gastrulation. Despite being implicated in many cellular processes, surprisingly little is known about the mechanism by which Gravin elicits cell shape changes. In this work, we use in vitro cell spreading assays to demonstrate that the Gravin N-terminus containing the three MARCKS-like basic regions (BRs) is necessary and sufficient to regulate cell shape in vitro. We show that the conserved phosphorylation sites in the BRs are essential for their function in these assays. We further demonstrate that the Gravin BRs are necessary for in vivo function during gastrulation in zebrafish. Together, these results provide an important step forward in understanding the mechanism of Gravin function in cell shape regulation and provide valuable insight into how Gravin acts as a cytoskeletal regulator.
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Affiliation(s)
- Douglas C Weiser
- Department of Biochemistry, University of Washington, Seattle WA 98195
| | | | - James S Lang
- Department of Biochemistry, University of Washington, Seattle WA 98195
| | - David Kimelman
- Department of Biochemistry, University of Washington, Seattle WA 98195
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17
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Scholten A, Aye TT, Heck AJR. A multi-angular mass spectrometric view at cyclic nucleotide dependent protein kinases: in vivo characterization and structure/function relationships. MASS SPECTROMETRY REVIEWS 2008; 27:331-353. [PMID: 18381623 DOI: 10.1002/mas.20166] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Mass spectrometry has evolved in recent years to a well-accepted and increasingly important complementary technique in molecular and structural biology. Here we review the many contributions mass spectrometry based studies have made in recent years in our understanding of the important cyclic nucleotide activated protein kinase A (PKA) and protein kinase G (PKG). We both describe the characterization of kinase isozymes, substrate phosphorylation, binding partners and post-translational modifications by proteomics based methodologies as well as their structural and functional properties as revealed by native mass spectrometry, H/D exchange MS and ion mobility. Combining all these mass spectrometry based data with other biophysical and biochemical data has been of great help to unravel the intricate regulation of kinase function in the cell in all its magnificent complexity.
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Affiliation(s)
- Arjen Scholten
- Biomolecular Mass Spectrometry & Proteomics Group, Utrecht Institute of Pharmaceutical Sciences and Bijvoet Center for Biomolecular Research, Utrecht University, Sorbonnelaan 16, 3584CA, Utrecht, The Netherlands
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18
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Wassler MJ, Shur BD, Zhou W, Geng YJ. Characterization of a novel ubiquitin-conjugating enzyme that regulates beta1,4-galactosyltransferase-1 in embryonic stem cells. Stem Cells 2008; 26:2006-18. [PMID: 18511602 DOI: 10.1634/stemcells.2007-1080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this study we identified a novel galactosyltransferase 1-associating protein (GTAP) by cDNA cloning from a murine embryonic cDNA library using the two-hybrid yeast system. GTAP is expressed in early embryonic tissues, as well as in adult tissues with active cell turnover, and belongs to the class III ubiquitin-conjugating (E2) enzyme family. Its COOH-terminal domain contains a consensus sequence for ubiquitin binding shared by all the ubiquitin-conjugating enzymes, whereas its NH(2)-terminal domain appears critical for the binding and internalization of cell surface galactosyltransferase 1 (GalT1) in embryonic stem cells through a monensin- and MG132-dependent pathway. We have found that GTAP regulates GalT1-associated, laminin-dependent embryonic cell adhesion and the formation of embryoid bodies. Thus, GTAP functions as an evolutionarily conserved E2 enzyme, which may participate in intercellular adhesion and embryonic development. Disclosure of potential conflicts of interest is found at the end of this article.
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Affiliation(s)
- Michael J Wassler
- Center for Cardiovascular Biology and Atherosclerosis Research, Division of Cardiology, Department of Internal Medicine, The University of Texas Health Science Center at Houston, School of Medicine, Houston 77030, USA.
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19
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Abstract
Cell-surface carbohydrate chains are known to contribute to cell migration, interaction, and proliferation. beta-1,4-galactosyltransferase-I (beta-1,4-GalT-I), which is one of the best-studied glycosyltransferases, plays a key role in the synthesis of type 2 chains in N-glycans and the core 2 branch in O-glycans. Recently, it has been reported that skin wound healing is significantly delayed in beta-1,4-GalT-I mice. However, the expression of beta-1,4-GalT-I and its biological function in the skin wound-healing process remain to be elucidated. We used real-time polymerase chain reaction to demonstrate that the expression of beta-1,4-GalT-I mRNA reached plateau values at 12 hours after skin was injured and remained elevated until 11 days after the injury. Furthermore, lectin blotting showed that beta-1,4-galactosylated carbohydrate chains were also increased after skin injury. A double-staining method combining lectin-fluorescent staining with RCA-I and immunofluorescence was first used to determine the cellular localization of beta-1,4-galactosylated carbohydrate chains. Morphological analysis showed that the chains were primarily expressed in neutrophils and partially expressed in macrophages, endothelial cells, and collagen. Our results suggest that beta-1,4-GalT-I and beta-1,4-galactosylated carbohydrate chains participate in leukocyte recruitment, angiogenesis, and collagen deposition in the skin wound-healing process.
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20
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Spatiotemporal patterns of SSeCKS expression after rat spinal cord injury. Neurochem Res 2008; 33:1735-48. [PMID: 18307037 DOI: 10.1007/s11064-008-9617-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2007] [Accepted: 01/30/2008] [Indexed: 10/22/2022]
Abstract
Src suppressed C kinase substrate (SSeCKS) was identified as a PKC substrate/PKC-binding protein, which plays a role in mitogenic regulatory activity and has a function in the control of cell signaling and cytoskeletal arrangement. However its distribution and function in the central nervous system (CNS) lesion remain unclear. In this study, we mainly investigated the mRNA and protein expression and cellular localization of SSeCKS during spinal cord injury (SCI). Real-time PCR and Western blot analysis revealed that SSeCKS was present in normal whole spinal cord. It gradually increased, reached a peak at 3 days for its mRNA level and 5 days for its protein level after SCI, and then declined during the following days. In ventral horn, the expression of SSeCKS underwent a temporal pattern that was similar with the whole spinal cord in both mRNA and protein level. However, in dorsal horn, the mRNA and protein for SSeCKS expression were significantly increased at 1 day for its mRNA level and 3 days for its protein level, and then gradually declined to the baseline level, ultimately up-regulated again from 7 to 14 days. The protein expression of SSeCKS was further analysed by immunohistochemistry. The positively stained areas for SSeCKS changed with the similar pattern to that of protein expression detected by immunoblotting analysis. Double immunofluorescence staining showed that SSeCKS immunoreactivity (IR) was found in neurons, astrocytes, oligodendrocytes of spinal cord tissues within 5 mm from the lesion site. Importantly, injury-induced expression of SSeCKS was co-labeled by active caspase-3 (apoptotic marker), Tau-1 (the marker for pathological oligodendrocyte) and beta-1,4-galactosyltransferase 1 (GalT). All the results suggested that SSeCKS might play important roles in spinal cord pathophysiology and further research is needed to have a good understanding of its function and mechanism.
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21
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Chen L, Qin J, Cheng C, Liu H, Niu S, Qian J, Sun L, Xiao F, Shi S, Shen A. Developmental regulation of SSeCKS expression in rat brain. J Mol Neurosci 2007; 32:9-15. [PMID: 17873283 DOI: 10.1007/s12031-007-0002-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Revised: 11/30/1999] [Accepted: 11/25/2006] [Indexed: 11/25/2022]
Abstract
SSeCKS (src suppressed C kinase substrate) was identified as a PKC substrate/PKC-binding protein, which plays a role in mitogenic regulatory activity and has a function in the control of cell signaling and cytoskeletal arrangement. Previous studies showed that expression of SSeCKS mRNA and protein levels were developmentally regulated in rat testis and the molecular might have some effects on the process of spermiogenesis. Here we carried out experiments to investigate the expression of SSeCKS in rat brain. Western blot analysis indicated that SSeCKS could be detected in the whole brain of developing rat embryos and reached its peak at 1 week after birth, while during mature period, its level was decreasing. Regional-distribution analysis showed that the expression pattern of SSeCKS in telencephalon, hippocampus and diencephalons was in accordance with the result from whole brain both in mRNA and protein level. However, in cerebellum, SSeCKS was almost in the same level, and in brainstem, the expression level was higher in 4-week-old rat brain than in 1-week-old one. Immunohistochemistry results showed SSeCKS was in diffused and granule-like distribution. Double immunofluorescence staining showed that it was expressed by some GFAP positive cells. All the results suggested that SSeCKS might affect brain development and further research is needed to have a good understanding of its function and mechanism.
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Affiliation(s)
- Li Chen
- Department of Pathology, Medical School of Nantong University (Former Nantong Medical College), Nantong 226001, People's Republic of China
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22
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Weiser DC, Pyati UJ, Kimelman D. Gravin regulates mesodermal cell behavior changes required for axis elongation during zebrafish gastrulation. Genes Dev 2007; 21:1559-71. [PMID: 17575056 PMCID: PMC1891432 DOI: 10.1101/gad.1535007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Convergent extension of the mesoderm is the major driving force of vertebrate gastrulation. During this process, mesodermal cells move toward the future dorsal side of the embryo, then radically change behavior as they initiate extension of the body axis. How cells make this transition in behavior is unknown. We have identified the scaffolding protein and tumor suppressor Gravin as a key regulator of this process in zebrafish embryos. We show that Gravin is required for the conversion of mesodermal cells from a highly migratory behavior to the medio-laterally intercalative behavior required for body axis extension. In the absence of Gravin, paraxial mesodermal cells fail to shut down the protrusive activity mediated by the Rho/ROCK/Myosin II pathway, resulting in embryos with severe extension defects. We propose that Gravin functions as an essential scaffold for regulatory proteins that suppress the migratory behavior of the mesoderm during gastrulation, and suggest that this function also explains how Gravin inhibits invasive behaviors in metastatic cells.
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Affiliation(s)
- Douglas C. Weiser
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
| | - Ujwal J. Pyati
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
| | - David Kimelman
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
- Corresponding author.E-MAIL ; FAX (206) 616-8676
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23
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Cheng C, Liu H, Ge H, Qian J, Qin J, Sun L, Shen A. Essential role of Src suppressed C kinase substrates in endothelial cell adhesion and spreading. Biochem Biophys Res Commun 2007; 358:342-8. [PMID: 17482576 DOI: 10.1016/j.bbrc.2007.04.147] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Accepted: 04/23/2007] [Indexed: 01/28/2023]
Abstract
Integrin-mediated substrate adhesion of endothelial cells leads to dynamic rearrangement of the actin cytoskeleton. Protein kinase C (PKC) stimulates reorganization of microfilaments and adhesion, but the mechanism by which this occurs is unknown. Src suppressed C kinase substrate (SSeCKS) is a PKC substrate that may play an important role in regulating actin cytoskeleton. We found that SSeCKS was localized to focal adhesion sites soon after cell adhesion and that SSeCKS translocated from the membrane to the cytosol during the process of cell spreading. Using small interfering RNAs specific to SSeCKS, we show that RPMVEC cells in which SSeCKS expression was inhibited reduce adhesion and spread on LN through blocking the formation of actin stress fibers and focal adhesions. These results demonstrated SSeCKS modulate endothelial cells adhesion and spreading by reorganization of the actin cytoskeleton.
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Affiliation(s)
- Chun Cheng
- Institute of Nautical Medicine, Nantong University, Nantong 226001, China
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24
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Qian J, Cheng C, Liu H, Chen J, Yan M, Niu S, Qin J, Sun L, Liu L, Gu J, Shen A. Expression of beta-1,4-galactosyltransferase-I in rat during inflammation. Inflammation 2007; 30:59-68. [PMID: 17372842 DOI: 10.1007/s10753-007-9022-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 01/22/2007] [Indexed: 01/24/2023]
Abstract
beta-1,4-Galactosyltransferase-I (beta-1,4-GalT-I) which is one of the best-studied glycosyltransferases, plays a key role in the synthesis of selectin ligands such as sialy Lewis (sLe( x )) and sulfated sLe( x ). Previous studies showed that inflammatory responses of beta-1,4-GalT-I-deficient mice were impaired because of the defect in selectin-ligand biosynthesis. However, the expression of beta-1,4-GalT-I during inflammation and its biological function remains to be elucidated. Real-time PCR showed that intraperitoneal administration of LPS strongly induced beta-1,4-GalT-I mRNA expression in the lung, heart, liver, spleen, kidney, lymph node, hippocampus, and testis, as well as in the cerebral cortex. In the rat lung, liver and testis, LPS stimulation of beta-1,4-GalT-I mRNA expression is time-dependent and biphasic. Lectin-fluorescent staining with RCA-I showed that LPS induced expression of galactose-containing glycans in rat lung and liver to the higher lever. Morphology analysis observed that galactose-containing glycans and beta-1,4-GalT-I mRNA was mostly expressed in neutrophils, macrophages and endothelial cells. These findings indicated that beta-1,4-GalT-I may play an important role in the inflammation reaction.
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Affiliation(s)
- Ji Qian
- Department of Microbiology and Immunology, Medical School of Nantong University (Former Nantong Medical College), Nantong 226001, People's Republic of China
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25
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Li Z, Wang H, Zong H, Sun Q, Kong X, Jiang J, Gu J. Downregulation of beta1,4-galactosyltransferase 1 inhibits CDK11(p58)-mediated apoptosis induced by cycloheximide. Biochem Biophys Res Commun 2005; 327:628-36. [PMID: 15629159 DOI: 10.1016/j.bbrc.2004.12.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Indexed: 11/22/2022]
Abstract
Cyclin-dependent kinase 11 (CDK11; also named PITSLRE) is part of the large family of p34(cdc2)-related kinases whose functions appear to be linked with cell cycle progression, tumorigenesis, and apoptotic signaling. The mechanism that CDK11(p58) induces apoptosis is not clear. Some evidences suggested beta1,4-galactosyltransferase 1 (beta1,4-GT 1) might participate in apoptosis induced by CDK11(p58). In this study, we demonstrated that ectopically expressed beta1,4-GT 1 increased CDK11(p58)-mediated apoptosis induced by cycloheximide (CHX). In contrast, RNAi-mediated knockdown of beta1,4-GT 1 effectively inhibited apoptosis induced by CHX in CDK11(p58)-overexpressing cells. For example, the cell morphological and nuclear changes were reduced; the loss of cell viability was prevented and the number of cells in sub-G1 phase was decreased. Knock down of beta1,4-GT 1 also inhibited the release of cytochrome c from mitochondria and caspase-3 processing. Therefore, the cleavage of CDK11(p58) by caspase-3 was reduced. We proposed that beta1,4-GT 1 might contribute to the pro-apoptotic effect of CDK11(p58). This may represent a new mechanism of beta1,4-GT 1 in CHX-induced apoptosis of CDK11(p58)-overexpressing cells.
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Affiliation(s)
- Zejuan Li
- State Key Laboratory of Genetic Engineering and Gene Research Center, Shanghai Medical College of Fudan University, Box 103, Shanghai 200032, People's Republic of China
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26
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de la Cruz L, Steffgen K, Martin A, McGee C, Hathaway H. Apoptosis and involution in the mammary gland are altered in mice lacking a novel receptor, beta1,4-Galactosyltransferase I. Dev Biol 2004; 272:286-309. [PMID: 15282149 DOI: 10.1016/j.ydbio.2004.03.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Revised: 03/22/2004] [Accepted: 03/25/2004] [Indexed: 01/26/2023]
Abstract
Receptor-mediated cell-extracellular matrix (ECM) interactions are critical regulators of cell survival, and perturbing these signaling pathways can disrupt cellular differentiation and function in a variety of tissues, including the mammary gland. One such receptor is the cell surface-associated, long isoform of beta1,4-galactosyltransferase I (GalT I). Deletion of long GalT I leads to increased mammary ductal branching morphogenesis [Dev. Biol., 244 (2002) 114]. Here, we show that this expansion in the mammary epithelial (ME) cell compartment is accomplished through decreased apoptosis during pregnancy and involution. Decreased apoptosis during involution is concomitant with delayed alveolar collapse, persistent expression of the milk protein gene alpha-lactalbumin and delayed expression of genes associated with the tissue-remodeling phase of involution. Using 3-dimensional in vitro cultures, we show that the decrease in apoptosis is dependent on laminin 1, a ligand for surface GalT I, suggesting that surface GalT I negatively influences ECM-dependent cell survival, a novel function for an ECM receptor. In the best-studied examples, ECM promotes survival through integrin receptor-mediated activation of focal adhesion kinase (FAK). Aggregation of surface GalT I also activates FAK, therefore, we asked if FAK activation was altered in ME from long GalT I null mice. Activated FAK was appropriately localized to focal adhesions in long GalT I null ME. However, FAK activation was constitutively reduced 4.5-fold in long GalT I nulls relative to wild type. Expression of the integrin beta1 subunit was not affected by loss of long GalT I. Collectively, these results suggest that surface GalT I might negatively regulate ME cell survival by linking integrin-independent FAK activation to apoptotic rather than survival signaling events.
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Affiliation(s)
- Laura de la Cruz
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
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27
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Hathaway HJ, Evans SC, Dubois DH, Foote CI, Elder BH, Shur BD. Mutational analysis of the cytoplasmic domain of beta1,4-galactosyltransferase I: influence of phosphorylation on cell surface expression. J Cell Sci 2003; 116:4319-30. [PMID: 12966167 DOI: 10.1242/jcs.00720] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Beta1,4-galactosyltransferase I (GalT I) exists in two subcellular compartments where it performs two distinct functions. The majority of GalT I is localized in the Golgi complex where it participates in glycoprotein biosynthesis; however, a small portion of GalT I is expressed on the cell surface where it functions as a matrix receptor by binding terminal N-acetylglucosamine residues on extracellular glycoside ligands. The GalT I polypeptide occurs in two alternate forms that differ only in the length of their cytoplasmic domains. It is thought that the longer cytoplasmic domain is responsible for GalT I function as a cell surface receptor because of its ability to associate with the detergent-insoluble cytoskeleton. In this study, we demonstrate that the long GalT I cytoplasmic and transmembrane domains are capable of targeting a reporter protein to the plasma membrane, whereas the short cytoplasmic and transmembrane domains do not have this property. The surface-localized GalT I reporter protein partitions with the detergent-insoluble pool, a portion of which co-fractionates with caveolin-containing lipid rafts. Site-directed mutagenesis of the cytoplasmic domain identified a requirement for serine and threonine residues for cell surface expression and function. Replacing either the serine or threonine with aspartic acid reduces surface expression and function, whereas substitution with neutral alanine has no effect on surface expression or function. These results suggest that phosphorylation negatively regulates GalT I function as a surface receptor. Consistent with this, phosphorylation of the endogenous, full-length GalT I inhibits its stable expression on the cell surface. Thus, the 13 amino acid extension unique to the long GalT I isoform is required for GalT I expression on the cell surface, the function of which is regulated by phosphorylation.
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Affiliation(s)
- Helen J Hathaway
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
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28
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Shen A, Yan J, Ding F, Gu X, Zhu D, Gu J. Overexpression of beta-1,4-galactosyltransferase I in rat Schwann cells promotes the growth of co-cultured dorsal root ganglia. Neurosci Lett 2003; 342:159-62. [PMID: 12757889 DOI: 10.1016/s0304-3940(03)00271-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The cell surface beta-1,4-galactosyltransferase I (beta-1,4-GalT-I) functions as one of the receptors of laminin during the neurite outgrowth on basal lamina by binding to N-linked oligosaccharides in the laminin E8 domain. In this study, we demonstrated that the purified rat Schwann cells transfected with the expression plasmid of beta-1,4-GalT-I cDNA transiently promoted outgrowth and elongation of the neurites from co-cultured rat dorsal root ganglia, while those transfected with the antisense expression plasmid of beta-1,4-GalT-I had the opposite effects. These results suggested that the expression of beta-1,4-GalT-I in Schwann cells of peripheral nerve might promote both growth of developmental neuron and regeneration of injured nerve.
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Affiliation(s)
- Aiguo Shen
- Box 103, Gene Research Center, Shanghai Medical College of Fudan University (Former Shanghai Medical University), 200032, Shanghai, People's Republic of China
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29
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Coats SR, Pabón-Peña LM, Covington JW, Vaughan DE. Ligand-specific control of src-suppressed C kinase substrate gene expression. Biochem Biophys Res Commun 2002; 297:1112-20. [PMID: 12372401 DOI: 10.1016/s0006-291x(02)02275-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The src-suppressed C-kinase substrate, SSeCKS, is now recognized as a key regulator of cell signaling and cytoskeletal dynamics. However, few ligands that control SSeCKS expression have been identified. We report that platelet-derived growth factor-BB (PDGF-BB), lysophosphatidic acid (LPA), and eicosapentaenoic acid (EPA) potently modulate SSeCKS gene expression in cultured smooth muscle (RASM) cells relative to other bioactive ligands tested. In addition, EPA-dependent regulation of SSeCKS expression correlates with distinct changes in cell morphology and adhesion in RASM cells. Independent evidence that ligand-specific control of SSeCKS expression links to the regulation of cell adhesion and morphology was obtained using ras-transformed fibroblasts, KNRK. Sodium butyrate (NaB) upregulates SSeCKS mRNA and protein expression corresponding to increased cell-spreading and adhesion. In addition, ectopic expression of recombinant SSeCKS recapitulates attributes of NaB-induced morphogenesis in KNRK cells. The data provide novel evidence that SSeCKS functions in PDGF-BB-, LPA-, EPA-, and NaB-mediated cell signaling.
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Affiliation(s)
- Stephen R Coats
- Department of Medicine, Vanderbilt University Medical Center and Nashville VAMC, Nashville, TN 37212-6300, USA.
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30
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Steffgen K, Dufraux K, Hathaway H. Enhanced branching morphogenesis in mammary glands of mice lacking cell surface beta1,4-galactosyltransferase. Dev Biol 2002; 244:114-33. [PMID: 11900463 DOI: 10.1006/dbio.2002.0599] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Development of the mammary gland is influenced both by the systemic hormonal environment and locally through cell-cell and cell-extracellular matrix (ECM) interactions. We have previously demonstrated aberrant mammary gland morphogenesis in transgenic mice with elevated levels of the long isoform of beta1,4-galactosyltransferase 1 (GalT), a proportion of which is targeted to the plasma membrane, where it plays a role in cell-ECM interactions. Here, we show that mammary glands of mice lacking the long GalT isoform exhibit a complementary phenotype. Cell-surface GalT activity was reduced by over 60%, but because the short GalT isoform is intact, total GalT activity was reduced only slightly relative to wild type. Mammary glands from long GalT-null mice were characterized by excess branching, and this phenotype was accompanied by altered expression of laminin chains. Laminin alpha1 and alpha3 were reduced 2.4- and 3.0-fold, respectively, while expression of laminin gamma2 was elevated 2.3-fold. The expression and cleavage of laminin gamma2 have been correlated with branching and cell migration, and Western blotting revealed an altered pattern in gamma2 cleavage products in long GalT-null mammary glands. We then examined the expression of metalloproteases that cleave laminins or that have been shown to play a role in mammary gland morphogenesis. Expression of MT1-MMP, a membrane-bound protease that can cleave laminin gamma2, was elevated 5.5-fold in the long GalT-nulls. MMP 7 was also elevated 5.1-fold. Our results suggest that expression of surface GalT is important for the proper regulation of matrix expression and deposition, which in turn regulates the proper branching morphogenesis of the mammary epithelial ductal system.
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Affiliation(s)
- Kristin Steffgen
- Department of Cell Biology and Physiology, University of New Mexico School of Medicine, Albuquerque, New Mexico 87131, USA
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31
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Lin X, Gelman IH. Calmodulin and cyclin D anchoring sites on the Src-suppressed C kinase substrate, SSeCKS. Biochem Biophys Res Commun 2002; 290:1368-75. [PMID: 11820772 DOI: 10.1006/bbrc.2002.6357] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
SSeCKS and its human orthologue, Gravin, are large scaffolding proteins that are thought to facilitate mitogenic control by anchoring key signal mediators such as protein kinase (PK) C, PKA, the plasma membrane associated isoform of alpha-1,4-galactosyltransferase (GalTase), beta2-adrenergic receptor, and cyclins. SSeCKS is also a major PKC substrate and phosphatidylserine-dependent PKC binding protein whose phosphorylation sites shares homology with a site in the MARCKS protein that encodes phosphorylation-sensitive calmodulin (CaM) binding activity. In the present study, we mapped the in vitro binding sites for CaM and cyclins on SSeCKS. Four CaM binding sites were identified by binding assays that conform to the so-called 1-5-10 motif. Notably, CaM binding was antagonized by prephosphorylation of SSeCKS by PKC. We also identified two major cyclin binding (CY) sites that overlap a major PKC phosphorylation site in SSeCKS (Ser(507/515)), and showed that cyclin D binding is attenuated if SSeCKS is prephosphorylated by PKC. These data suggest that the scaffolding activities of SSeCKS are modulated by mitogenically stimulated kinases such as PKC.
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Affiliation(s)
- Xueying Lin
- Department of Medicine and Ruttenberg Cancer Center, Mount Sinai School of Medicine, Box 1090, One Gustave L. Levy Place, New York, New York 10029-6574, USA
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32
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Abstract
Glycosyltransferases involved in N- and O-glycan chain elongation and termination are localized in the Golgi apparatus. Early evidence in support of this rule was based on fractionation techniques and was corroborated by numerous immunocytochemical studies. Usually these studies were confined to cultured cell lines exhibiting little differentiation features, such as HeLa cells. However, localization studies conducted in primary cell cultures (e.g., human umbilical vein endothelial cells), cells obtained ex vivo (e.g., sperm cells), and tissue sections (e.g., intestinal, renal, or hepatic tissue) often reveal ectopic localizations of glycosyltransferases usually at post-Golgi sites, including the plasma membrane. Hence, extracellular cues resulting from specific adhesion sites may influence post-Golgi trafficking routes, which may be reflected by ectopic localization of Golgi enzymes.
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Affiliation(s)
- Eric G Berger
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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