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Yang ML, Lam TT, Kanyo J, Kang I, Zhou ZS, Clarke SG, Mamula MJ. Natural isoaspartyl protein modification of ZAP70 alters T cell responses in lupus. Autoimmunity 2023; 56:2282945. [PMID: 37994408 PMCID: PMC10897934 DOI: 10.1080/08916934.2023.2282945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 11/08/2023] [Indexed: 11/24/2023]
Abstract
Protein posttranslational modifications (PTMs) arise in a number of normal cellular biological pathways and in response to pathology caused by inflammation and/or infection. Indeed, a number of PTMs have been identified and linked to specific autoimmune responses and metabolic pathways. One particular PTM, termed isoaspartyl (isoAsp or isoD) modification, is among the most common spontaneous PTM occurring at physiological pH and temperature. Herein, we demonstrate that isoAsp modifications arise within the ZAP70 protein tyrosine kinase upon T-cell antigen receptor (TCR) engagement. The enzyme protein L-isoaspartate O-methyltransferase (PCMT1, or PIMT, EC 2.1.1.77) evolved to repair isoaspartyl modifications in cells. In this regard, we observe that increased levels of isoAsp modification that arise under oxidative stress are correlated with reduced PIMT activity in patients with systemic lupus erythematosus (SLE). PIMT deficiency leads to T cell hyper-proliferation and hyper-phosphorylation through ZAP70 signaling. We demonstrate that inducing the overexpression of PIMT can correct the hyper-responsive phenotype in lupus T cells. Our studies reveal a phenotypic role of isoAsp modification and phosphorylation of ZAP70 in lupus T cell autoimmunity and provide a potential therapeutic target through the repair of isoAsp modification.
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Affiliation(s)
- Mei-Ling Yang
- Section of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Yale University, New Haven, CT, USA
| | - TuKiet T. Lam
- Keck MS & Proteomics Resource, WM Keck Foundation Biotechnology Resource Laboratory, New Haven, CT, USA
- Department of Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Jean Kanyo
- Keck MS & Proteomics Resource, WM Keck Foundation Biotechnology Resource Laboratory, New Haven, CT, USA
| | - Insoo Kang
- Section of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Yale University, New Haven, CT, USA
| | - Zhaohui Sunny Zhou
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA, USA
| | - Steven G. Clarke
- Department of Chemistry and Biochemistry, Molecular Biology Institute, UCLA, Los Angeles, CA, USA
| | - Mark J. Mamula
- Section of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Yale University, New Haven, CT, USA
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Lin Y, Wu F, Zhuang Y, Chu L, Ding T, Qu Q, Li X, Cui Y, Hong C. PCMT1 has Potential Prognostic Value and Promotes Cell Growth and Motility in Breast Cancer.. [DOI: 10.21203/rs.3.rs-2349165/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Abstract
Breast cancer (BC) is one of the frequently diagnosed cancers, and the leading cause of cancer-related death among women worldwide. The roles of protein L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1) in human cancer have been exploring, but the clinical significance and biological function of PCMT1 in BC are not yet clear. In this study, based on the TCGA-BRCA data set, the results showed that high expression of PCMT1 gene was significantly correlated with shorter overall survival (OS), disease specific survival (DSS) and progress free suvival (PFS) of BC patients. Utilizing the immunohistochemical assay, we found that PCMT1 protein was located in the cytoplasm of BC cells, and PCMT1 expression was only obviously correlated with progesterone receptor expression of patients (p < 0.05). Survival analysis showed that PCMT1 protein high-expression was an independent unfavorable prognostic factor for BC patients. The in vitro experiments revealed that PCMT1 could regulate growth, migration and invasion capacity of MCF-7 cell, and modulate the expression of AKT/GSK3β/mTOR signaling pathway, EMT and cell cycle-associated protein. In conclusion, PCMT1 was a potential unfavorable prognostic biomarker for BC patient and might influence the AKT/GSK3β/mTOR signaling pathway to regulate the growth and motility of MCF-7 cell.
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Affiliation(s)
- Yi-Wei Lin
- the Cancer Hospital of Shantou University Medical College
| | - Fang-Cai Wu
- the Cancer Hospital of Shantou University Medical College
| | - Yi-Xuan Zhuang
- the Cancer Hospital of Shantou University Medical College
| | - Ling-Yu Chu
- the Cancer Hospital of Shantou University Medical College
| | - Tian-Yan Ding
- the Cancer Hospital of Shantou University Medical College
| | - Qi-Qi Qu
- the Cancer Hospital of Shantou University Medical College
| | - Xin-Hao Li
- the Cancer Hospital of Shantou University Medical College
| | - Yu-Kun Cui
- the Cancer Hospital of Shantou University Medical College
| | - Chao-Qun Hong
- the Cancer Hospital of Shantou University Medical College
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3
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The Protein L-Isoaspartyl (D-Aspartyl) Methyltransferase Regulates Glial-to-Mesenchymal Transition and Migration Induced by TGF-β1 in Human U-87 MG Glioma Cells. Int J Mol Sci 2022; 23:ijms23105698. [PMID: 35628507 PMCID: PMC9146343 DOI: 10.3390/ijms23105698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 05/11/2022] [Accepted: 05/16/2022] [Indexed: 11/30/2022] Open
Abstract
The enzyme PIMT methylates abnormal aspartyl residues in proteins. U-87 MG cells are commonly used to study the most frequent brain tumor, glioblastoma. Previously, we reported that PIMT isoform I possessed oncogenic features when overexpressed in U-87 MG and U-251 MG glioma cells. Higher levels of wild-type PIMT stimulated migration and invasion in both glioma cell lines. Conversely, PIMT silencing reduced these migratory abilities of both cell lines. These results indicate that PIMT could play a critical role in glioblastoma growth. Here, we investigated for the first time, molecular mechanisms involving PIMT in the regulation of epithelial to mesenchymal transition (EMT) upon TGF-β1 treatments. Gene array analyses indicated that EMT genes but not PIMT gene were regulated in U-87 MG cells treated with TGF-β1. Importantly, PIMT silencing by siRNA inhibited in vitro migration in U-87 MG cells induced by TGF-β1. In contrast, overexpressed wild-type PIMT and TGF-β1 had additive effects on cell migration. When PIMT was inhibited by siRNA, this prevented Slug induction by TGF-β1, while Snail stimulation by TGF-β1 was increased. Indeed, overexpression of wild-type PIMT led to the opposite effects on Slug and Snail expression dependent on TGF-β1. These data highlighted the importance of PIMT in the EMT response dependent on TGF-β1 in U-87 MG glioma cells by an antagonist regulation in the expression of transcription factors Slug and Snail, which are critical players in EMT.
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Belkourchia F, Desrosiers RR. The enzyme L-isoaspartyl (D-aspartyl) methyltransferase promotes migration and invasion in human U-87 MG and U-251 MG glioblastoma cell lines. Biomed Pharmacother 2021; 140:111766. [PMID: 34082401 DOI: 10.1016/j.biopha.2021.111766] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 12/27/2022] Open
Abstract
The protein L-isoaspartyl (D-aspartyl) methyltransferase (PIMT) recognizes abnormal L-isoaspartyl and D-aspartyl residues in proteins. Among examined tissues, PIMT shows the highest level in the brain. The U-87 MG cell line is a commonly used cellular model to study the most frequent brain tumor, glioblastoma. Previously, we reported that PIMT amount increased when U-87 MG cells were detached from the extracellular matrix. Recently, we also showed that PIMT possessed pro-angiogenic properties. Together, these PIMT features led us to postulate that PIMT could play a critical role in glioblastoma growth. Here, we investigate PIMT role in U-87 MG cell viability, adhesion, migration, invasion, and colony formation and in the reorganization of the actin and tubulin cytoskeleton. PIMT inhibition by siRNA significantly reduced in vitro cell migration and invasion in various assays, including wound-healing assay, Boyden chambers coated with gelatin and Matrigel invasion assay. Conversely, in stably transfected U-87 MG cells overexpressing wild-type PIMT, cell migration, invasive capacity and colony formation significantly increased. However, in stably transfected cells with the gene encoding for mutated PIMT(D83V), despite of its overexpression, migration and invasion remained similar to those observed in control cells. In all these conditions, cell viability was unaffected. Importantly, overexpressed wild-type PIMT and mutated PIMT(D83V) have opposite effects on the organization of microtubules and actin cytoskeleton and thus on morphology of U-87 cells. These data highlighted the importance of PIMT level and its catalytic activity in migration and invasion of U-87 glioma cells and its possible contribution in cancer invasion during glioma growth.
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Affiliation(s)
- Fatima Belkourchia
- Université du Québec à Montréal, Département de chimie, C.P. 8888, Succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada
| | - Richard R Desrosiers
- Université du Québec à Montréal, Département de chimie, C.P. 8888, Succursale Centre-Ville, Montréal, Québec H3C 3P8, Canada.
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Simko V, Belvoncikova P, Csaderova L, Labudova M, Grossmannova K, Zatovicova M, Kajanova I, Skultety L, Barathova M, Pastorek J. PIMT Binding to C-Terminal Ala459 of CAIX Is Involved in Inside-Out Signaling Necessary for Its Catalytic Activity. Int J Mol Sci 2020; 21:ijms21228545. [PMID: 33198416 PMCID: PMC7696048 DOI: 10.3390/ijms21228545] [Citation(s) in RCA: 1] [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: 10/20/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 01/10/2023] Open
Abstract
Human carbonic anhydrase IX (CAIX), a unique member of the α carbonic anhydrase family, is a transmembrane glycoprotein with high enzymatic activity by which CAIX contributes to tumorigenesis through pH regulation. Due to its aberrant expression, CAIX is considered to be a marker of tumor hypoxia and a poor prognostic factor of several human cancers. Hypoxia-activated catalytic function of CAIX is dependent on posttranslational modification of its short intracellular domain. In this work, we have identified that C-terminal Ala459 residue, which is common across CAIX of various species as well as additional transmembrane isoforms, plays an important role in CAIX activation and in pH regulation. Moreover, structure prediction I-TASSER analysis revealed involvement of Ala459 in potential ligand binding. Using tandem mass spectrometry, Protein-L-isoaspartyl methyltransferase (PIMT) was identified as a novel interacting partner, further confirmed by an in vitro pulldown assay and an in situ proximity ligation assay. Indeed, suppression of PIMT led to increased alkalinization of culture media of C33a cells constitutively expressing CAIX in hypoxia. We suggest that binding of PIMT represents a novel intracellular signal required for enzymatic activity of CAIX with a potential unidentified downstream function.
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Affiliation(s)
- Veronika Simko
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
| | - Petra Belvoncikova
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
| | - Lucia Csaderova
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
| | - Martina Labudova
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
| | - Katarina Grossmannova
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
| | - Miriam Zatovicova
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
| | - Ivana Kajanova
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
| | - Ludovit Skultety
- Department of Rickettsiology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia;
| | - Monika Barathova
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
- Correspondence: ; Tel.: +421-2-5930-2461
| | - Jaromir Pastorek
- Department of Tumor Biology, Biomedical Research Center, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, 84505 Bratislava, Slovakia; (V.S.); (P.B.); (L.C.); (M.L.); (K.G.); (M.Z.); (I.K.); (J.P.)
- Faculty of Medicine, Slovak Medical University, Limbová 12, 833 03 Bratislava, Slovakia
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6
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Dong L, Li Y, Xue D, Liu Y. PCMT1 is an unfavorable predictor and functions as an oncogene in bladder cancer. IUBMB Life 2018. [PMID: 29517839 DOI: 10.1002/iub.1717] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Liming Dong
- Department of Urology; The Fourth Affiliated Hospital of China Medical University, No. 4 Chongshan Road East, Huanggu District; Liaoning Shenyang China
| | - Yanpei Li
- Department of Urology; The Fourth Affiliated Hospital of China Medical University, No. 4 Chongshan Road East, Huanggu District; Liaoning Shenyang China
| | - Dongwei Xue
- Department of Urology; The Fourth Affiliated Hospital of China Medical University, No. 4 Chongshan Road East, Huanggu District; Liaoning Shenyang China
| | - Yili Liu
- Department of Urology; The Fourth Affiliated Hospital of China Medical University, No. 4 Chongshan Road East, Huanggu District; Liaoning Shenyang China
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7
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Yamashita M, Ogasawara M, Kawasaki Y, Niisato M, Saito H, Kasai S, Maesawa C, Maemondo M, Yamauchi K. Deficiency of protein-L-isoaspartate (D-aspartate) O-methyl-transferase expression under endoplasmic reticulum stress promotes epithelial mesenchymal transition in lung adenocarcinoma. Oncotarget 2018; 9:13287-13300. [PMID: 29568357 PMCID: PMC5862578 DOI: 10.18632/oncotarget.24324] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 01/19/2018] [Indexed: 11/25/2022] Open
Abstract
A prognostic association between the novel chaperone protein-L-isoaspartate (D-aspartate) O-methyltransferase (PIMT) and lung adenocarcinoma has recently been reported. Here, we evaluated the functional roles of PIMT in the progression of lung adenocarcinoma. PIMT expression was detectable in 6 lung adenocarcinoma cell lines: A549, H441, H460, H1650, Calu 1, and Calu 6 cell lines. In A549 and H441 cells, knockdown by PIMT using silencing RNA of PIMT (si-PIMT) and/or small hairpin-RNA (sh-PIMT) induced a decrease in the expression of E-cadherin with an increase in vimentin expression, indicating that the epithelial to mesenchymal transition (EMT) was induced. Cell mobility, including migration and invasion capability, was increased in sh-PIMT A549 stable and si-PIMT H441 cells compared to in control cells. Endoplasmic reticulum (ER) stress, such as Thapsigargin (Tg) stress and hypoxia, induced EMT in A549 cells but not in other cell types, with an increase in GRP78 expression, whereas overexpression of PIMT reduced the EMT and cell invasion under stress conditions. The expression of hypoxia inducible factor-1 alpha (HIF1α) and Twist increased in sh-PIMT A549 and si-PIMT H441 cells, and Tg stress increased HIF1α expression levels in A549 cells in a dose-dependent manner. Moreover, LW6, an HIF1α inhibitor, reduced EMT, cancer invasion, and the levels of Twist in sh-PIMT A549 cells. Our results indicate that deficiency of supplemental PIMT expression under ER stress facilitates EMT and cell invasion in some cell types of lung adenocarcinoma.
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Affiliation(s)
- Masahiro Yamashita
- Department of Pulmonary Medicine, Allergy and Immunological Diseases, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan
| | - Masahito Ogasawara
- Department of Pharmacology, Graduate School of Medicine, Ehime University, Toon, Ehime, Japan
| | - Yasushi Kawasaki
- Department of Health Chemistry, School of Pharmacology, Iwate Medical University, Shiwa, Iwate, Japan
| | - Miyuki Niisato
- Department of Pulmonary Medicine, Allergy and Immunological Diseases, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan
| | - Heisuke Saito
- Department of Pulmonary Medicine, Allergy and Immunological Diseases, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan
| | - Shuya Kasai
- Department of Cancer Biology, Iwate Medical University, Shiwa, Iwate, Japan
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Chihaya Maesawa
- Department of Cancer Biology, Iwate Medical University, Shiwa, Iwate, Japan
| | - Makoto Maemondo
- Department of Pulmonary Medicine, Allergy and Immunological Diseases, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan
| | - Kohei Yamauchi
- Department of Pulmonary Medicine, Allergy and Immunological Diseases, School of Medicine, Iwate Medical University, Morioka, Iwate, Japan
- Geriatric Health Services Facilities, Keiyu, Morioka, Japan
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8
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Ouanouki A, Desrosiers RR. The enzyme l-isoaspartyl (d-aspartyl) methyltransferase is required for VEGF-dependent endothelial cell migration and tubulogenesis. Mol Cell Biochem 2016; 413:37-46. [DOI: 10.1007/s11010-015-2637-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 12/23/2015] [Indexed: 02/08/2023]
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9
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Davis FM, Stewart TA, Thompson EW, Monteith GR. Targeting EMT in cancer: opportunities for pharmacological intervention. Trends Pharmacol Sci 2014; 35:479-88. [PMID: 25042456 DOI: 10.1016/j.tips.2014.06.006] [Citation(s) in RCA: 240] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 06/21/2014] [Accepted: 06/23/2014] [Indexed: 02/09/2023]
Abstract
The spread of cancer cells to distant organs represents a major clinical challenge in the treatment of cancer. Epithelial-mesenchymal transition (EMT) has emerged as a key regulator of metastasis in some cancers by conferring an invasive phenotype. As well as facilitating metastasis, EMT is thought to generate cancer stem cells and contribute to therapy resistance. Therefore, the EMT pathway is of great therapeutic interest in the treatment of cancer and could be targeted either to prevent tumor dissemination in patients at high risk of developing metastatic lesions or to eradicate existing metastatic cancer cells in patients with more advanced disease. In this review, we discuss approaches for the design of EMT-based therapies in cancer, summarize evidence for some of the proposed EMT targets, and review the potential advantages and pitfalls of each approach.
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Affiliation(s)
- Felicity M Davis
- School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia
| | - Teneale A Stewart
- School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia
| | - Erik W Thompson
- St. Vincent's Institute, Fitzroy, VIC, Australia; University of Melbourne Department of Surgery, St Vincent's Hospital, Fitzroy, VIC, Australia; Institute of Health and Biomedical Innovation, Queensland Institute of Technology, Kelvin Grove, QLD, Australia
| | - Gregory R Monteith
- School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia.
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Hooshmand S, Ghaderi A, Yusoff K, Thilakavathy K, Rosli R, Mojtahedi Z. Differentially Expressed Proteins in ER+MCF7 and ER-MDA-MB-231 Human Breast Cancer Cells by RhoGDI-α Silencing and Overexpression. Asian Pac J Cancer Prev 2014; 15:3311-7. [DOI: 10.7314/apjcp.2014.15.7.3311] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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11
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Kim JH, Lee YG, Yoo S, Oh J, Jeong D, Song WK, Yoo BC, Rhee MH, Park J, Cha SH, Hong S, Cho JY. Involvement of Src and the actin cytoskeleton in the antitumorigenic action of adenosine dialdehyde. Biochem Pharmacol 2013; 85:1042-56. [DOI: 10.1016/j.bcp.2013.01.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 12/28/2012] [Accepted: 01/18/2013] [Indexed: 01/06/2023]
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MacKay KB, Lowenson JD, Clarke SG. Wortmannin reduces insulin signaling and death in seizure-prone Pcmt1-/- mice. PLoS One 2012; 7:e46719. [PMID: 23071621 PMCID: PMC3465263 DOI: 10.1371/journal.pone.0046719] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 09/01/2012] [Indexed: 12/23/2022] Open
Abstract
L-isoaspartyl (D-aspartyl) O-methyltransferase deficient mice (Pcmt1−/−) accumulate isomerized aspartyl residues in intracellular proteins until their death due to seizures at approximately 45 days. Previous studies have shown that these mice have constitutively activated insulin signaling in their brains, and that these brains are 20–30% larger than those from age-matched wild-type animals. To determine whether insulin pathway activation and brain enlargement is responsible for the fatal seizures, we administered wortmannin, an inhibitor of the phosphoinositide 3-kinase that catalyzes an early step in the insulin pathway. Oral wortmannin reduced the average brain size in the Pcmt1−/− animals to within 6% of the wild-type DMSO administered controls, and nearly doubled the lifespan of Pcmt1−/− at 60% survival of the original population. Immunoblotting revealed significant decreases in phosphorylation of Akt, PDK1, and mTOR in Pcmt1−/− mice and Akt and PDK1 in wild-type animals upon treatment with wortmannin. These data suggest activation of the insulin pathway and its resulting brain enlargement contributes to the early death of Pcmt1−/− mice, but is not solely responsible for the early death observed in these animals.
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Affiliation(s)
- Kennen B. MacKay
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jonathan D. Lowenson
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Steven G. Clarke
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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