1
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Soto I, McManus R, Navarrete W, Kasanga EA, Doshier K, Nejtek VA, Salvatore MF. Aging accelerates locomotor decline in PINK1 knockout rats in association with decreased nigral, but not striatal, dopamine and tyrosine hydroxylase expression. Exp Neurol 2024; 376:114771. [PMID: 38580154 DOI: 10.1016/j.expneurol.2024.114771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/15/2024] [Accepted: 04/02/2024] [Indexed: 04/07/2024]
Abstract
Parkinson's disease (PD) rodent models provide insight into the relationship between nigrostriatal dopamine (DA) signaling and locomotor function. Although toxin-based rat models produce frank nigrostriatal neuron loss and eventual motor decline characteristic of PD, the rapid nature of neuronal loss may not adequately translate premotor traits, such as cognitive decline. Unfortunately, rodent genetic PD models, like the Pink1 knockout (KO) rat, often fail to replicate the differential severity of striatal DA and tyrosine hydroxylase (TH) loss, and a bradykinetic phenotype, reminiscent of human PD. To elucidate this inconsistency, we evaluated aging as a progression factor in the timing of motor and non-motor cognitive impairments. Male PINK1 KO and age-matched wild type (WT) rats were evaluated in a longitudinal study from 3 to 16 months old in one cohort, and in a cross-sectional study of young adult (6-7 months) and aged (18-19 months) in another cohort. Young adult PINK1 KO rats exhibited hyperkinetic behavior associated with elevated DA and TH in the substantia nigra (SN), which decreased therein, but not striatum, in the aged KO rats. Additionally, norepinephrine levels decreased in aged KO rats in the prefrontal cortex (PFC), paired with a higher DA levels in young and aged KO. Although a younger age of onset characterizes familial forms of PD, our results underscore the critical need to consider age-related factors. Moreover, the results indicate that compensatory mechanisms may exist to preserve locomotor function, evidenced by increased DA in the SN early in the lifespan, in response to deficient PINK1 function, which declines with aging and the onset of motor decline.
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Affiliation(s)
- Isabel Soto
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Robert McManus
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Walter Navarrete
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Ella A Kasanga
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Kirby Doshier
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Vicki A Nejtek
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America
| | - Michael F Salvatore
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America.
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Hubbard NW, Ames JM, Maurano M, Chu LH, Somfleth KY, Gokhale NS, Werner M, Snyder JM, Lichauco K, Savan R, Stetson DB, Oberst A. ADAR1 mutation causes ZBP1-dependent immunopathology. Nature 2022; 607:769-775. [PMID: 35859177 PMCID: PMC9339495 DOI: 10.1038/s41586-022-04896-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 05/23/2022] [Indexed: 01/22/2023]
Abstract
The RNA-editing enzyme ADAR1 is essential for the suppression of innate immune activation and pathology caused by aberrant recognition of self-RNA, a role it carries out by disrupting the duplex structure of endogenous double-stranded RNA species1,2. A point mutation in the sequence encoding the Z-DNA-binding domain (ZBD) of ADAR1 is associated with severe autoinflammatory disease3-5. ZBP1 is the only other ZBD-containing mammalian protein6, and its activation can trigger both cell death and transcriptional responses through the kinases RIPK1 and RIPK3, and the protease caspase 8 (refs. 7-9). Here we show that the pathology caused by alteration of the ZBD of ADAR1 is driven by activation of ZBP1. We found that ablation of ZBP1 fully rescued the overt pathology caused by ADAR1 alteration, without fully reversing the underlying inflammatory program caused by this alteration. Whereas loss of RIPK3 partially phenocopied the protective effects of ZBP1 ablation, combined deletion of caspase 8 and RIPK3, or of caspase 8 and MLKL, unexpectedly exacerbated the pathogenic effects of ADAR1 alteration. These findings indicate that ADAR1 is a negative regulator of sterile ZBP1 activation, and that ZBP1-dependent signalling underlies the autoinflammatory pathology caused by alteration of ADAR1.
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Affiliation(s)
| | - Joshua M Ames
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Megan Maurano
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Lan H Chu
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Kim Y Somfleth
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Nandan S Gokhale
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Margo Werner
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington, Seattle, WA, USA
| | - Katrina Lichauco
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Ram Savan
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Daniel B Stetson
- Department of Immunology, University of Washington, Seattle, WA, USA
| | - Andrew Oberst
- Department of Immunology, University of Washington, Seattle, WA, USA.
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3
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Xu Y, Lu J, Tang Y, Xie W, Zhang H, Wang B, Zhang S, Hou W, Zou C, Jiang P, Zhang W. RETRACTED: PINK1 deficiency in gastric cancer compromises mitophagy, promotes the Warburg effect, and facilitates M2 polarization of macrophages. Cancer Lett 2022; 529:19-36. [PMID: 34979165 DOI: 10.1016/j.canlet.2021.12.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 12/25/2021] [Accepted: 12/28/2021] [Indexed: 12/16/2022]
Abstract
This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief and authors. Following the publication of the above article, the Editor was notified by a concerned reader that the authors supplied duplicated images. Specifically, that in Fig. 5A, both FACS panels are identical and in Fig. 5E, two different proteins (HK2 and PDK1) have the same western blot. After checking the data in relation with Fig. 5A and Fig. 5E, the authors have confirmed that the two pictures indeed have the problems of duplication. The authors reported that this problem came from the authors’ unintentional behavior, which may be due to a copy and paste error in the manner of image processing. The authors sincerely apologize for the inconvenience caused to our Editors and readers. Due to this duplication error, the authors and Editor have made the decision to retract this paper.
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Affiliation(s)
- Ying Xu
- Department of Laboratory Center, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Jiawei Lu
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Yinbing Tang
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Wenjie Xie
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Heteng Zhang
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Beibei Wang
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Shouliang Zhang
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Wenji Hou
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Chen Zou
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China
| | - Pengcheng Jiang
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China.
| | - Wenbo Zhang
- Department of General Surgery, Affiliated People's Hospital of Jiangsu University, Zhenjiang, China.
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4
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Vos M, Dulovic-Mahlow M, Mandik F, Frese L, Kanana Y, Haissatou Diaw S, Depperschmidt J, Böhm C, Rohr J, Lohnau T, König IR, Klein C. Ceramide accumulation induces mitophagy and impairs β-oxidation in PINK1 deficiency. Proc Natl Acad Sci U S A 2021; 118:e2025347118. [PMID: 34686591 PMCID: PMC8639384 DOI: 10.1073/pnas.2025347118] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2021] [Indexed: 11/18/2022] Open
Abstract
Energy production via the mitochondrial electron transport chain (ETC) and mitophagy are two important processes affected in Parkinson's disease (PD). Interestingly, PINK1, mutations of which cause early-onset PD, plays a key role in both processes, suggesting that these two mechanisms are connected. However, the converging link of both pathways currently remains enigmatic. Recent findings demonstrated that lipid aggregation, along with defective mitochondria, is present in postmortem brains of PD patients. In addition, an increasing body of evidence shows that sphingolipids, including ceramide, are altered in PD, supporting the importance of lipids in the pathophysiology of PD. Here, we identified ceramide to play a crucial role in PINK1-related PD that was previously linked almost exclusively to mitochondrial dysfunction. We found ceramide to accumulate in mitochondria and to negatively affect mitochondrial function, most notably the ETC. Lowering ceramide levels improved mitochondrial phenotypes in pink1-mutant flies and PINK1-deficient patient-derived fibroblasts, showing that the effects of ceramide are evolutionarily conserved. In addition, ceramide accumulation provoked ceramide-induced mitophagy upon PINK1 deficiency. As a result of the ceramide accumulation, β-oxidation in PINK1 mutants was decreased, which was rescued by lowering ceramide levels. Furthermore, stimulation of β-oxidation was sufficient to rescue PINK1-deficient phenotypes. In conclusion, we discovered a cellular mechanism resulting from PD-causing loss of PINK1 and found a protective role of β-oxidation in ETC dysfunction, thus linking lipids and mitochondria in the pathophysiology of PINK1-related PD. Furthermore, our data nominate β-oxidation and ceramide as therapeutic targets for PD.
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Affiliation(s)
- Melissa Vos
- Institute of Neurogenetics, University of Luebeck, 23562 Luebeck, Germany;
| | | | - Frida Mandik
- Institute of Neurogenetics, University of Luebeck, 23562 Luebeck, Germany
| | - Lisa Frese
- Institute of Neurogenetics, University of Luebeck, 23562 Luebeck, Germany
| | - Yuliia Kanana
- Institute of Neurogenetics, University of Luebeck, 23562 Luebeck, Germany
| | | | | | - Claudia Böhm
- Institute of Neurogenetics, University of Luebeck, 23562 Luebeck, Germany
| | - Jonas Rohr
- Institute of Neurogenetics, University of Luebeck, 23562 Luebeck, Germany
| | - Thora Lohnau
- Institute of Neurogenetics, University of Luebeck, 23562 Luebeck, Germany
| | - Inke R König
- Institut für Medizinische Biometrie und Statistik, University of Luebeck, 23562 Luebeck, Germany
| | - Christine Klein
- Institute of Neurogenetics, University of Luebeck, 23562 Luebeck, Germany;
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Souza ACO, Martin-Vicente A, Nywening AV, Ge W, Lowes DJ, Peters BM, Fortwendel JR. Loss of Septation Initiation Network (SIN) kinases blocks tissue invasion and unlocks echinocandin cidal activity against Aspergillus fumigatus. PLoS Pathog 2021; 17:e1009806. [PMID: 34370772 PMCID: PMC8376064 DOI: 10.1371/journal.ppat.1009806] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/19/2021] [Accepted: 07/16/2021] [Indexed: 11/18/2022] Open
Abstract
Although considered effective treatment for many yeast fungi, the therapeutic efficacy of the echinocandin class of antifungals for invasive aspergillosis (IA) is limited. Recent studies suggest intense kinase- and phosphatase-mediated echinocandin adaptation in A. fumigatus. To identify A. fumigatus protein kinases required for survival under echinocandin stress, we employed CRISPR/Cas9-mediated gene targeting to generate a protein kinase disruption mutant library in a wild type genetic background. Cell wall and echinocandin stress screening of the 118 disruption mutants comprising the library identified only five protein kinase disruption mutants displaying greater than 4-fold decreased echinocandin minimum effective concentrations (MEC) compared to the parental strain. Two of these mutated genes, the previously uncharacterized A. fumigatus sepL and sidB genes, were predicted to encode protein kinases functioning as core components of the Septation Initiation Network (SIN), a tripartite kinase cascade that is necessary for septation in fungi. As the A. fumigatus SIN is completely uncharacterized, we sought to explore these network components as effectors of echinocandin stress survival. Our data show that mutation of any single SIN kinase gene caused complete loss of hyphal septation and increased susceptibility to cell wall stress, as well as widespread hyphal damage and loss of viability in response to echinocandin stress. Strikingly, mutation of each SIN kinase gene also resulted in a profound loss of virulence characterized by lack of tissue invasive growth. Through the deletion of multiple novel regulators of hyphal septation, we show that the non-invasive growth phenotype is not SIN-kinase dependent, but likely due to hyphal septation deficiency. Finally, we also find that echinocandin therapy is highly effective at eliminating residual tissue burden in mice infected with an aseptate strain of A. fumigatus. Together, our findings suggest that inhibitors of septation could enhance echinocandin-mediated killing while simultaneously limiting the invasive potential of A. fumigatus hyphae.
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Affiliation(s)
- Ana Camila Oliveira Souza
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Adela Martin-Vicente
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Ashley V. Nywening
- Integrated Program in Biomedical Sciences, College of Graduate Health Sciences, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Wenbo Ge
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - David J. Lowes
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Brian M. Peters
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- Department of Microbiology, Immunology, and Biochemistry, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Jarrod R. Fortwendel
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- Department of Microbiology, Immunology, and Biochemistry, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- * E-mail:
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6
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Kim SH, Shin HJ, Yoon CM, Lee SW, Sharma L, Dela Cruz CS, Kang MJ. PINK1 Inhibits Multimeric Aggregation and Signaling of MAVS and MAVS-Dependent Lung Pathology. Am J Respir Cell Mol Biol 2021; 64:592-603. [PMID: 33577398 PMCID: PMC8086043 DOI: 10.1165/rcmb.2020-0490oc] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 01/20/2021] [Indexed: 12/16/2022] Open
Abstract
Mitochondria have emerged as important signaling organelles where intracellular perturbations are integrated and, consequently, intracellular signaling pathways are modulated to execute appropriate cellular functions. MAVS (mitochondrial antiviral signaling protein) represents such an example that functions as a platform molecule to mediate mitochondrial innate immune signaling. Recently, multimeric aggregation of MAVS has been identified as a key molecular process for its signaling. The underlying mechanisms to regulate this, however, are still incompletely understood. We hypothesized that PINK1 (PTEN-induced kinase 1) plays an important role in the regulation of multimeric MAVS aggregation and its consequent pathobiology. To test whether PINK1 interacts with MAVS, bimolecular fluorescence complementation analysis and IP were performed. RLH (RIG-I-like helicase) and NLRP3 inflammasome signaling were evaluated by in vitro assay. In vivo functional significance of PINK1 in the regulation of MAVS signaling was evaluated from both murine modeling of influenza viral infection and bleomycin-induced experimental pulmonary fibrosis, wherein MAVS plays important roles. Multimeric MAVS aggregation was induced by mitochondria dysfunction, and, during this event, the stabilized PINK1 interacted physically with MAVS and antagonized multimeric MAVS aggregation. Accordingly, the MAVS-mediated antiviral innate immune and NLRP3 inflammasome signaling were enhanced in PINK1 deficiency. In addition, in vivo studies revealed that MAVS-mediated pulmonary antiviral innate immune responses and fibrotic responses after bleomycin injury were enhanced in PINK1 deficiency. In conclusion, these results establish a new role of PINK1 in the regulation of MAVS signaling and the consequent pulmonary pathobiology.
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Affiliation(s)
- Sang-Hun Kim
- Department of Internal Medicine, Section of Pulmonary, Critical Care and Sleep Medicine, Yale University School of Medicine, New Haven, Connecticut; and
| | - Hyeon Jun Shin
- Department of Internal Medicine, Section of Pulmonary, Critical Care and Sleep Medicine, Yale University School of Medicine, New Haven, Connecticut; and
| | - Chang Min Yoon
- Department of Internal Medicine, Section of Pulmonary, Critical Care and Sleep Medicine, Yale University School of Medicine, New Haven, Connecticut; and
| | - Sei Won Lee
- Department of Internal Medicine, Section of Pulmonary, Critical Care and Sleep Medicine, Yale University School of Medicine, New Haven, Connecticut; and
- Department of Pulmonary and Critical Care Medicine, and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Lokesh Sharma
- Department of Internal Medicine, Section of Pulmonary, Critical Care and Sleep Medicine, Yale University School of Medicine, New Haven, Connecticut; and
| | - Charles S. Dela Cruz
- Department of Internal Medicine, Section of Pulmonary, Critical Care and Sleep Medicine, Yale University School of Medicine, New Haven, Connecticut; and
| | - Min-Jong Kang
- Department of Internal Medicine, Section of Pulmonary, Critical Care and Sleep Medicine, Yale University School of Medicine, New Haven, Connecticut; and
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Malik AU, Karapetsas A, Nirujogi RS, Mathea S, Chatterjee D, Pal P, Lis P, Taylor M, Purlyte E, Gourlay R, Dorward M, Weidlich S, Toth R, Polinski NK, Knapp S, Tonelli F, Alessi DR. Deciphering the LRRK code: LRRK1 and LRRK2 phosphorylate distinct Rab proteins and are regulated by diverse mechanisms. Biochem J 2021; 478:553-578. [PMID: 33459343 PMCID: PMC7886321 DOI: 10.1042/bcj20200937] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/08/2021] [Accepted: 01/18/2021] [Indexed: 01/05/2023]
Abstract
Autosomal dominant mutations in LRRK2 that enhance kinase activity cause Parkinson's disease. LRRK2 phosphorylates a subset of Rab GTPases including Rab8A and Rab10 within its effector binding motif. Here, we explore whether LRRK1, a less studied homolog of LRRK2 that regulates growth factor receptor trafficking and osteoclast biology might also phosphorylate Rab proteins. Using mass spectrometry, we found that in LRRK1 knock-out cells, phosphorylation of Rab7A at Ser72 was most impacted. This residue lies at the equivalent site targeted by LRRK2 on Rab8A and Rab10. Accordingly, recombinant LRRK1 efficiently phosphorylated Rab7A at Ser72, but not Rab8A or Rab10. Employing a novel phospho-specific antibody, we found that phorbol ester stimulation of mouse embryonic fibroblasts markedly enhanced phosphorylation of Rab7A at Ser72 via LRRK1. We identify two LRRK1 mutations (K746G and I1412T), equivalent to the LRRK2 R1441G and I2020T Parkinson's mutations, that enhance LRRK1 mediated phosphorylation of Rab7A. We demonstrate that two regulators of LRRK2 namely Rab29 and VPS35[D620N], do not influence LRRK1. Widely used LRRK2 inhibitors do not inhibit LRRK1, but we identify a promiscuous inhibitor termed GZD-824 that inhibits both LRRK1 and LRRK2. The PPM1H Rab phosphatase when overexpressed dephosphorylates Rab7A. Finally, the interaction of Rab7A with its effector RILP is not affected by LRRK1 phosphorylation and we observe that maximal stimulation of the TBK1 or PINK1 pathway does not elevate Rab7A phosphorylation. Altogether, these findings reinforce the idea that the LRRK enzymes have evolved as major regulators of Rab biology with distinct substrate specificity.
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Affiliation(s)
- Asad U. Malik
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Athanasios Karapetsas
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Raja S. Nirujogi
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Sebastian Mathea
- Structural Genomics Consortium, Institute for Pharmaceutical Chemistry and Buchmann Institute for Molecular Life Sciences, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany
| | - Deep Chatterjee
- Structural Genomics Consortium, Institute for Pharmaceutical Chemistry and Buchmann Institute for Molecular Life Sciences, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany
| | - Prosenjit Pal
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Pawel Lis
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Matthew Taylor
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Elena Purlyte
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Robert Gourlay
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Mark Dorward
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Simone Weidlich
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Rachel Toth
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Nicole K. Polinski
- Michael J Fox Foundation for Parkinson's Research, Grand Central Station, PO Box 4777, New York, NY 10163, U.S.A
| | - Stefan Knapp
- Structural Genomics Consortium, Institute for Pharmaceutical Chemistry and Buchmann Institute for Molecular Life Sciences, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 9, D-60438 Frankfurt am Main, Germany
| | - Francesca Tonelli
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
| | - Dario R. Alessi
- Medical Research Council (MRC) Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, U.K
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Mizusawa A, Watanabe A, Yamada M, Kamei R, Shimomura Y, Kitaura Y. BDK Deficiency in Cerebral Cortex Neurons Causes Neurological Abnormalities and Affects Endurance Capacity. Nutrients 2020; 12:nu12082267. [PMID: 32751134 PMCID: PMC7469005 DOI: 10.3390/nu12082267] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/22/2020] [Accepted: 07/22/2020] [Indexed: 12/26/2022] Open
Abstract
Branched-chain amino acid (BCAA) catabolism is regulated by its rate-limiting enzyme, branched-chain α-keto acid dehydrogenase (BCKDH), which is negatively regulated by BCKDH kinase (BDK). Loss of BDK function in mice and humans leads to dysregulated BCAA catabolism accompanied by neurological symptoms such as autism; however, which tissues or cell types are responsible for the phenotype has not been determined. Since BDK is highly expressed in neurons compared to astrocytes, we hypothesized that neurons are the cell type responsible for determining the neurological features of BDK deficiency. To test this hypothesis, we generated mice in which BDK deletion is restricted to neurons of the cerebral cortex (BDKEmx1-KO mice). Although BDKEmx1-KO mice were born and grew up normally, they showed clasped hind limbs when held by the tail and lower brain BCAA concentrations compared to control mice. Furthermore, these mice showed a marked increase in endurance capacity after training compared to control mice. We conclude that BDK in neurons of the cerebral cortex is essential for maintaining normal neurological functions in mice, and that accelerated BCAA catabolism in that region may enhance performance in running endurance following training.
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Affiliation(s)
- Anna Mizusawa
- Laboratory of Nutritional Biochemistry, Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan; (A.M.); (A.W.); (M.Y.); (R.K.)
| | - Ayako Watanabe
- Laboratory of Nutritional Biochemistry, Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan; (A.M.); (A.W.); (M.Y.); (R.K.)
| | - Minori Yamada
- Laboratory of Nutritional Biochemistry, Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan; (A.M.); (A.W.); (M.Y.); (R.K.)
| | - Rina Kamei
- Laboratory of Nutritional Biochemistry, Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan; (A.M.); (A.W.); (M.Y.); (R.K.)
| | - Yoshiharu Shimomura
- Department of Food and Nutritional Sciences, College of Bioscience and Biotechnology, Chubu University, Kasugai, Aichi 487-8501, Japan;
| | - Yasuyuki Kitaura
- Laboratory of Nutritional Biochemistry, Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan; (A.M.); (A.W.); (M.Y.); (R.K.)
- Correspondence:
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9
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Faergeman SL, Evans H, Attfield KE, Desel C, Kuttikkatte SB, Sommerlund M, Jensen LT, Frokiaer J, Friese MA, Matthews PM, Luchtenborg C, Brügger B, Oturai AB, Dendrou CA, Fugger L. A novel neurodegenerative spectrum disorder in patients with MLKL deficiency. Cell Death Dis 2020; 11:303. [PMID: 32358523 PMCID: PMC7195448 DOI: 10.1038/s41419-020-2494-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/14/2022]
Abstract
Mixed lineage kinase domain-like (MLKL) is the main executor of necroptosis, an inflammatory form of programmed cell death. Necroptosis is implicated in combating infections, but also in contributing to numerous other clinical conditions, including cardiovascular diseases and neurodegenerative disorders. Inhibition of necroptosis is therefore of therapeutic interest. Here we report two siblings both of whom over the course of 35 years developed a similar progressive, neurodegenerative spectrum disorder characterized by paresis, ataxia and dysarthria. Magnetic resonance imaging of their central nervous system (CNS) revealed severe global cerebral volume loss and atrophy of the cerebellum and brainstem. These brothers are homozygous for a rare haplotype identified by whole genome sequencing carrying a frameshift variant in MLKL, as well as an in-frame deletion of one amino acid in the adjacent fatty acid 2-hydroxylase (FA2H) gene. Functional studies of patient-derived primary cells demonstrated that the variant in MLKL leads to a deficiency of MLKL protein resulting in impairment of necroptosis. Conversely, shotgun lipidomic analysis of the variant in FA2H shows no impact on either the abundance or the enzymatic activity of the encoded hydroxylase. To our knowledge, this is the first report of complete necroptosis deficiency in humans. The findings may suggest that impaired necroptosis is a novel mechanism of neurodegeneration, promoting a disorder that shares some clinical features with primary progressive multiple sclerosis (PPMS) and other neurodegenerative diseases. Importantly, the necroptotic deficiency does not cause symptoms outside the nervous system, nor does it confer susceptibility to infections. Given the current interest in pharmacological inhibition of necroptosis by targeting MLKL and its associated pathways, this strategy should be developed with caution, with careful consideration of the possible development of adverse neurological effects.
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Affiliation(s)
- Soren L Faergeman
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- Department of Clinical Medicine, Aarhus University Hospital, Aarhus, DK-8200, Denmark
| | - Hayley Evans
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Kathrine E Attfield
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Christiane Desel
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Subita Balaram Kuttikkatte
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Mette Sommerlund
- Department of Clinical Medicine, Aarhus University Hospital, Aarhus, DK-8200, Denmark
| | - Lise Torp Jensen
- Department of Clinical Medicine, Aarhus University Hospital, Aarhus, DK-8200, Denmark
| | - Jorgen Frokiaer
- Department of Clinical Medicine, Aarhus University Hospital, Aarhus, DK-8200, Denmark
| | - Manuel A Friese
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, Hamburg, 20246, Germany
| | - Paul M Matthews
- Division of Brain Sciences, Department of Medicine, UK Dementia Research Institute, Imperial College London, London, SW7 2AZ, UK
| | | | - Britta Brügger
- Heidelberg University Biochemistry Center (BZH), Heidelberg, D-69120, Germany
| | - Annette Bang Oturai
- Danish Multiple Sclerosis Center, Department of Neurology, Copenhagen University Hospital, Copenhagen, 2100, Denmark
| | - Calliope A Dendrou
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Lars Fugger
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK.
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK.
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10
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Zhang J, Qin D, Yang YJ, Hu GQ, Qin XX, Du CT, Chen W. MLKL deficiency inhibits DSS-induced colitis independent of intestinal microbiota. Mol Immunol 2019; 107:132-141. [PMID: 30738250 DOI: 10.1016/j.molimm.2019.01.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/28/2019] [Accepted: 01/28/2019] [Indexed: 12/11/2022]
Abstract
The maintenance of intestinal tissue homeostasis is vital for the resistance against inflammatory bowel diseases (IBDs). Necroptosis is identified as an alternative mode of regulated cell death, which plays a pivotal role in tissue homeostasis. Thus, the roles of RIP3-mediated necroptosis in intestinal inflammation have been extensively studied. However, the biological implications of the mixed lineage kinase-like protein (MLKL), a molecule downstream of RIP3 in gut remain unclear. In this study, the role of MLKL in DSS-induced colitis was examined, and the contribution of gut microbiota was also determined. Compared with non-littermate WT mice, the survival rate, clinical score, intestinal damage and intestinal mucosal barrier integrity of non-littermate MLKL-deficient mice are significantly improved. MLKL deficiency prevents inflammatory cytokines production and MAPK signaling activation. Hence, MLKL deficiency inhibits DSS-induced colitis. Moreover, we proved that DSS susceptibility difference between two genotypes is not driven by intestinal microbiota based on the co-housing of two non-littermate genotypes and qPCR detection of fecal dominant bacterial taxa.
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Affiliation(s)
- Jie Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Di Qin
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yong-Jun Yang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Gui-Qiu Hu
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xiao-Xia Qin
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Chong-Tao Du
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Wei Chen
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China.
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11
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Germino EA, Miller JP, Diehl L, Swanson CJ, Durinck S, Modrusan Z, Miner JH, Shaw AS. Homozygous KSR1 deletion attenuates morbidity but does not prevent tumor development in a mouse model of RAS-driven pancreatic cancer. PLoS One 2018; 13:e0194998. [PMID: 29596465 PMCID: PMC5875795 DOI: 10.1371/journal.pone.0194998] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 03/14/2018] [Indexed: 01/04/2023] Open
Abstract
Given the frequency with which MAP kinase signaling is dysregulated in cancer, much effort has been focused on inhibiting RAS signaling for therapeutic benefit. KSR1, a pseudokinase that interacts with RAF, is a potential target; it was originally cloned in screens for suppressors of constitutively active RAS, and its deletion prevents RAS-mediated transformation of mouse embryonic fibroblasts. In this work, we used a genetically engineered mouse model of pancreatic cancer to assess whether KSR1 deletion would influence tumor development in the setting of oncogenic RAS. We found that Ksr1-/- mice on this background had a modest but significant improvement in all-cause morbidity compared to Ksr1+/+ and Ksr1+/- cohorts. Ksr1-/- mice, however, still developed tumors, and precursor pancreatic intraepithelial neoplastic (PanIN) lesions were detected within a similar timeframe compared to Ksr1+/+ mice. No significant differences in pERK expression or in proliferation were noted. RNA sequencing also did not reveal any unique genetic signature in Ksr1-/- tumors. Further studies will be needed to determine whether and in what settings KSR inhibition may be clinically useful.
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Affiliation(s)
- Elizabeth A. Germino
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Research Biology, Genentech, South San Francisco, California, United States of America
| | - Joseph P. Miller
- Division of Nephrology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Lauri Diehl
- Department of Pathology, Genentech, South San Francisco, California, United States of America
| | - Carter J. Swanson
- Department of Research Biology, Genentech, South San Francisco, California, United States of America
| | - Steffen Durinck
- Department of Bioinformatics and Computational Biology, Genentech, South San Francisco, California, United States of America
- Department of Molecular Biology, Genentech, South San Francisco, California, United States of America
| | - Zora Modrusan
- Department of Molecular Biology, Genentech, South San Francisco, California, United States of America
| | - Jeffrey H. Miner
- Division of Nephrology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Andrey S. Shaw
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Research Biology, Genentech, South San Francisco, California, United States of America
- * E-mail:
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12
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Honarpisheh M, Foresto-Neto O, Desai J, Steiger S, Gómez LA, Popper B, Boor P, Anders HJ, Mulay SR. Phagocytosis of environmental or metabolic crystalline particles induces cytotoxicity by triggering necroptosis across a broad range of particle size and shape. Sci Rep 2017; 7:15523. [PMID: 29138474 PMCID: PMC5686194 DOI: 10.1038/s41598-017-15804-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 11/02/2017] [Indexed: 01/09/2023] Open
Abstract
In crystallopathies, crystals or crystalline particles of environmental and metabolic origin deposit within tissues, induce inflammation, injury and cell death and eventually lead to organ-failure. The NLRP3-inflammasome is involved in mediating crystalline particles-induced inflammation, but pathways leading to cell death are still unknown. Here, we have used broad range of intrinsic and extrinsic crystal- or crystalline particle-sizes and shapes, e.g. calcium phosphate, silica, titanium dioxide, cholesterol, calcium oxalate, and monosodium urate. As kidney is commonly affected by crystallopathies, we used human and murine renal tubular cells as a model system. We showed that all of the analysed crystalline particles induce caspase-independent cell death. Deficiency of MLKL, siRNA knockdown of RIPK3, or inhibitors of necroptosis signaling e.g. RIPK-1 inhibitor necrostatin-1s, RIPK3 inhibitor dabrafenib, and MLKL inhibitor necrosulfonamide, partially protected tubular cells from crystalline particles cytotoxicity. Furthermore, we identify phagocytosis of crystalline particles as an upstream event in their cytotoxicity since a phagocytosis inhibitor, cytochalasin D, prevented their cytotoxicity. Taken together, our data confirmed the involvement of necroptosis as one of the pathways leading to cell death in crystallopathies. Our data identified RIPK-1, RIPK3, and MLKL as molecular targets to limit tissue injury and organ failure in crystallopathies.
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Affiliation(s)
- Mohsen Honarpisheh
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich, 80336, Germany
| | - Orestes Foresto-Neto
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich, 80336, Germany
| | - Jyaysi Desai
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich, 80336, Germany
| | - Stefanie Steiger
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich, 80336, Germany
| | - Lidia Anguiano Gómez
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich, 80336, Germany
| | - Bastian Popper
- Biomedical Center (BMC), Department for Cell Biology, Ludwig-Maximilians University, Munich, 82152, Germany
| | - Peter Boor
- Institute of Pathology & Dept. of Nephrology, University Clinic of RWTH Aachen, Aachen, 52074, Germany
| | - Hans-Joachim Anders
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich, 80336, Germany.
| | - Shrikant R Mulay
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich, 80336, Germany.
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13
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Alejandro EU, Bozadjieva N, Blandino-Rosano M, Wasan MA, Elghazi L, Vadrevu S, Satin L, Bernal-Mizrachi E. Overexpression of Kinase-Dead mTOR Impairs Glucose Homeostasis by Regulating Insulin Secretion and Not β-Cell Mass. Diabetes 2017; 66:2150-2162. [PMID: 28546423 PMCID: PMC5521866 DOI: 10.2337/db16-1349] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 05/01/2017] [Indexed: 12/20/2022]
Abstract
Regulation of glucose homeostasis by insulin depends on β-cell growth and function. Nutrients and growth factor stimuli converge on the conserved protein kinase mechanistic target of rapamycin (mTOR), existing in two complexes, mTORC1 and mTORC2. To understand the functional relevance of mTOR enzymatic activity in β-cell development and glucose homeostasis, we generated mice overexpressing either one or two copies of a kinase-dead mTOR mutant (KD-mTOR) transgene exclusively in β-cells. We examined glucose homeostasis and β-cell function of these mice fed a control chow or high-fat diet. Mice with two copies of the transgene [RIPCre;KD-mTOR (Homozygous)] develop glucose intolerance due to a defect in β-cell function without alterations in β-cell mass with control chow. Islets from RIPCre;KD-mTOR (Homozygous) mice showed reduced mTORC1 and mTORC2 signaling along with transcripts and protein levels of Pdx-1. Islets with reduced mTORC2 signaling in their β-cells (RIPCre;Rictorfl/fl) also showed reduced Pdx-1. When challenged with a high-fat diet, mice carrying one copy of KD-mTOR mutant transgene developed glucose intolerance and β-cell insulin secretion defect but showed no changes in β-cell mass. These findings suggest that the mTOR-mediated signaling pathway is not essential to β-cell growth but is involved in regulating β-cell function in normal and diabetogenic conditions.
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Affiliation(s)
- Emilyn U Alejandro
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN
| | - Nadejda Bozadjieva
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Manuel Blandino-Rosano
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Division of Endocrinology, Metabolism and Diabetes, University of Miami, Miami, FL
| | - Michelle Ann Wasan
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN
| | - Lynda Elghazi
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | | | - Leslie Satin
- Department of Pharmacology, University of Michigan, Ann Arbor, MI
| | - Ernesto Bernal-Mizrachi
- Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
- Division of Endocrinology, Metabolism and Diabetes, University of Miami, Miami, FL
- VA Ann Arbor Healthcare System, Ann Arbor, MI
- Miami VA Healthcare System, Miami, FL
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14
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Xu M, Kitaura Y, Ishikawa T, Kadota Y, Terai C, Shindo D, Morioka T, Ota M, Morishita Y, Ishihara K, Shimomura Y. Endurance performance and energy metabolism during exercise in mice with a muscle-specific defect in the control of branched-chain amino acid catabolism. PLoS One 2017; 12:e0180989. [PMID: 28719620 PMCID: PMC5515431 DOI: 10.1371/journal.pone.0180989] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 06/23/2017] [Indexed: 01/13/2023] Open
Abstract
It is known that the catabolism of branched-chain amino acids (BCAAs) in skeletal muscle is suppressed under normal and sedentary conditions but is promoted by exercise. BCAA catabolism in muscle tissues is regulated by the branched-chain α-keto acid (BCKA) dehydrogenase complex, which is inactivated by phosphorylation by BCKA dehydrogenase kinase (BDK). In the present study, we used muscle-specific BDK deficient mice (BDK-mKO mice) to examine the effect of uncontrolled BCAA catabolism on endurance exercise performance and skeletal muscle energy metabolism. Untrained control and BDK-mKO mice showed the same performance; however, the endurance performance enhanced by 2 weeks of running training was somewhat, but significantly less in BDK-mKO mice than in control mice. Skeletal muscle of BDK-mKO mice had low levels of glycogen. Metabolome analysis showed that BCAA catabolism was greatly enhanced in the muscle of BDK-mKO mice and produced branched-chain acyl-carnitine, which induced perturbation of energy metabolism in the muscle. These results suggest that the tight regulation of BCAA catabolism in muscles is important for homeostasis of muscle energy metabolism and, at least in part, for adaptation to exercise training.
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Affiliation(s)
- Minjun Xu
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yasuyuki Kitaura
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Takuya Ishikawa
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yoshihiro Kadota
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Chihaya Terai
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Daichi Shindo
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Takashi Morioka
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Miki Ota
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yukako Morishita
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Kengo Ishihara
- Faculty of Agriculture, Ryukoku University, Fushimi-ku, Kyoto, Japan
| | - Yoshiharu Shimomura
- Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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15
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González-Juarbe N, Bradley KM, Shenoy AT, Gilley RP, Reyes LF, Hinojosa CA, Restrepo MI, Dube PH, Bergman MA, Orihuela CJ. Pore-forming toxin-mediated ion dysregulation leads to death receptor-independent necroptosis of lung epithelial cells during bacterial pneumonia. Cell Death Differ 2017; 24:917-928. [PMID: 28387756 PMCID: PMC5423117 DOI: 10.1038/cdd.2017.49] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 02/07/2017] [Accepted: 03/07/2017] [Indexed: 12/29/2022] Open
Abstract
We report that pore-forming toxins (PFTs) induce respiratory epithelial cell necroptosis independently of death receptor signaling during bacterial pneumonia. Instead, necroptosis was activated as a result of ion dysregulation arising from membrane permeabilization. PFT-induced necroptosis required RIP1, RIP3 and MLKL, and could be induced in the absence or inhibition of TNFR1, TNFR2 and TLR4 signaling. We detected activated MLKL in the lungs from mice and nonhuman primates experiencing Serratia marcescens and Streptococcus pneumoniae pneumonia, respectively. We subsequently identified calcium influx and potassium efflux as the key initiating signals responsible for necroptosis; also that mitochondrial damage was not required for necroptosis activation but was exacerbated by MLKL activation. PFT-induced necroptosis in respiratory epithelial cells did not involve CamKII or reactive oxygen species. KO mice deficient in MLKL or RIP3 had increased survival and reduced pulmonary injury during S. marcescens pneumonia. Our results establish necroptosis as a major cell death pathway active during bacterial pneumonia and that necroptosis can occur without death receptor signaling.
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Affiliation(s)
- Norberto González-Juarbe
- Department of Microbiology, The University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2170, USA
| | - Kelley Margaret Bradley
- Department of Microbiology, The University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2170, USA
| | - Anukul Taranath Shenoy
- Department of Microbiology, The University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2170, USA
| | - Ryan Paul Gilley
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Luis Felipe Reyes
- Division of Pulmonary Diseases and Critical Care Medicine, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Cecilia Anahí Hinojosa
- Division of Pulmonary Diseases and Critical Care Medicine, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Marcos Ignacio Restrepo
- Division of Pulmonary Diseases and Critical Care Medicine, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Division of Pulmonary Diseases and Critical Care Medicine, South Texas Veterans Health Care System, San Antonio, TX 78229, USA
| | - Peter Herman Dube
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Molly Ann Bergman
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Carlos Javier Orihuela
- Department of Microbiology, The University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294-2170, USA
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
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16
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Choiniere J, Wu J, Wang L. Pyruvate Dehydrogenase Kinase 4 Deficiency Results in Expedited Cellular Proliferation through E2F1-Mediated Increase of Cyclins. Mol Pharmacol 2017; 91:189-196. [PMID: 28003426 PMCID: PMC5325080 DOI: 10.1124/mol.116.106757] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 12/09/2016] [Indexed: 12/14/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is a common form of cancer with prevalence worldwide. There are many factors that lead to the development and progression of HCC. This study aimed to identify potential new tumor suppressors, examine their function as cell cycle modulators, and investigate their impact on the cyclin family of proteins and cyclin-dependent kinases (CDKs). In this study, the pyruvate dehydrogenase kinase (PDK)4 gene was shown to have potential tumor suppressor characteristics. PDK4 expression was significantly downregulated in human HCC. Pdk4-/- mouse liver exhibited a consistent increase in cell cycle regulator proteins, including cyclin D1, cyclin E1, cyclin A2, some associated CDKs, and transcription factor E2F1. PDK4-knockdown HCC cells also progressed faster through the cell cycle, which concurrently expressed high levels of cyclins and E2F1 as seen in the Pdk4-/- mice. Interestingly, the induced cyclin E1 and cyclin A2 caused by Pdk4 deficiency was repressed by arsenic treatment in mouse liver and in HCC cells. E2f1 deficiency in E2f1-/- mouse liver or knockdown E2F1 using small hairpin RNAs in HCC cells significantly decreased cyclin E1, cyclin A2, and E2F1 proteins. In contrast, inhibition of PDK4 activity in HCC cells increased cyclin E1, cyclin A2, and E2F1 proteins. These findings demonstrate that PDK4 is a critical regulator of hepatocyte proliferation via E2F1-mediated regulation of cyclins.
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Affiliation(s)
- Jonathan Choiniere
- Department of Physiology and Neurobiology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut (J.C., J.W., L.W.); Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut (L.W.); Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut (L.W.); and School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China (L.W.)
| | - Jianguo Wu
- Department of Physiology and Neurobiology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut (J.C., J.W., L.W.); Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut (L.W.); Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut (L.W.); and School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China (L.W.)
| | - Li Wang
- Department of Physiology and Neurobiology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut (J.C., J.W., L.W.); Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut (L.W.); Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut (L.W.); and School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China (L.W.)
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17
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Stauch KL, Villeneuve LM, Purnell PR, Ottemann BM, Emanuel K, Fox HS. Loss of Pink1 modulates synaptic mitochondrial bioenergetics in the rat striatum prior to motor symptoms: concomitant complex I respiratory defects and increased complex II-mediated respiration. Proteomics Clin Appl 2016; 10:1205-1217. [PMID: 27568932 PMCID: PMC5810131 DOI: 10.1002/prca.201600005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 07/21/2016] [Accepted: 08/24/2016] [Indexed: 11/08/2022]
Abstract
PURPOSE Mutations in PTEN-induced putative kinase 1 (Pink1), a mitochondrial serine/threonine kinase, cause a recessive inherited form of Parkinson's disease (PD). Pink1 deletion in rats results in a progressive PD-like phenotype, characterized by significant motor deficits starting at 4 months of age. Despite the evidence of mitochondrial dysfunction, the pathogenic mechanism underlying disease due to Pink1-deficiency remains obscure. EXPERIMENTAL DESIGN Striatal synaptic mitochondria from 3-month-old Pink1-deficient rats were characterized using bioenergetic and mass spectroscopy (MS)-based proteomic analyses. RESULTS Striatal synaptic mitochondria from Pink1-deficient rats exhibit decreased complex I-driven respiration and increased complex II-mediated respiration compared with wild-type rats. MS-based proteomics revealed 69 of the 811 quantified mitochondrial proteins were differentially expressed between Pink1-deficient rats and controls. Down-regulation of several electron carrier proteins, which shuttle electrons to reduce ubiquinone at complex III, in the Pink1-knockouts suggests disruption of the linkage between fatty acid, amino acid, and choline metabolism and the mitochondrial respiratory system. CONCLUSIONS AND CLINICAL RELEVANCE These results suggest that complex II activity is increased to compensate for loss of electron transfer mechanisms due to reduced complex I activity and loss of electron carriers within striatal nerve terminals early during disease progression. This may contribute to the pathogenesis of PD.
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Affiliation(s)
- Kelly L. Stauch
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Lance M. Villeneuve
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Phillip R. Purnell
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Brendan M. Ottemann
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Katy Emanuel
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Howard S. Fox
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
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18
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Dorn GW. Central Parkin: The evolving role of Parkin in the heart. Biochim Biophys Acta 2016; 1857:1307-1312. [PMID: 26992930 DOI: 10.1016/j.bbabio.2016.03.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 02/11/2016] [Accepted: 03/13/2016] [Indexed: 11/17/2022]
Abstract
Parkin is familiar to many because of its link to Parkinson's disease, and to others because of its well-characterized role as a central factor mediating selective mitophagy of damaged mitochondria for mitochondrial quality control. The genetic connection between Parkin and Parkinson's disease derives from clinical gene-association studies, whereas our mechanistic understanding of Parkin functioning in mitophagy is based almost entirely on work performed in cultured cells. Surprisingly, experimental evidence linking the disease and the presumed mechanism derives almost entirely from fruit flies; germline Parkin deficient mice do not develop Parkinson's disease phenotypes. Moreover, genetic manipulation of Parkin signaling in mouse hearts does not support a central role for Parkin in homeostatic mitochondrial quality control in this mitochondria-rich and -dependent organ. Here, I provide an overview of data suggesting that (in mouse hearts at least) Parkin functions more as a stress-induced and developmentally-programmed facilitator of cardiomyocyte mitochondrial turnover. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016.
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Affiliation(s)
- Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States.
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19
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Técher H, Koundrioukoff S, Carignon S, Wilhelm T, Millot GA, Lopez BS, Brison O, Debatisse M. Signaling from Mus81-Eme2-Dependent DNA Damage Elicited by Chk1 Deficiency Modulates Replication Fork Speed and Origin Usage. Cell Rep 2016; 14:1114-1127. [PMID: 26804904 DOI: 10.1016/j.celrep.2015.12.093] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 11/10/2015] [Accepted: 12/19/2015] [Indexed: 11/20/2022] Open
Abstract
Mammalian cells deficient in ATR or Chk1 display moderate replication fork slowing and increased initiation density, but the underlying mechanisms have remained unclear. We show that exogenous deoxyribonucleosides suppress both replication phenotypes in Chk1-deficient, but not ATR-deficient, cells. Thus, in the absence of exogenous stress, depletion of either protein impacts the replication dynamics through different mechanisms. In addition, Chk1 deficiency, but not ATR deficiency, triggers nuclease-dependent DNA damage. Avoiding damage formation through invalidation of Mus81-Eme2 and Mre11, or preventing damage signaling by turning off the ATM pathway, suppresses the replication phenotypes of Chk1-deficient cells. Damage and resulting DDR activation are therefore the cause, not the consequence, of replication dynamics modulation in these cells. Together, we identify moderate reduction of precursors available for replication as an additional outcome of DDR activation. We propose that resulting fork slowing, and subsequent firing of backup origins, helps replication to proceed along damaged templates.
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Affiliation(s)
- Hervé Técher
- Institut Curie, PSL Research University, CNRS UMR 3244, 75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris Cedex 05, France
| | - Stéphane Koundrioukoff
- Institut Curie, PSL Research University, CNRS UMR 3244, 75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris Cedex 05, France
| | - Sandra Carignon
- Institut Curie, PSL Research University, CNRS UMR 3244, 75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris Cedex 05, France
| | - Therese Wilhelm
- Institut Curie, PSL Research University, CNRS UMR 3244, 75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris Cedex 05, France
| | - Gaël A Millot
- Institut Curie, PSL Research University, CNRS UMR 3244, 75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris Cedex 05, France
| | - Bernard S Lopez
- Institut de Cancérologie Gustave Roussy, CNRS UMR 8200 and Université Paris Sud, 94805 Villejuif, France
| | - Olivier Brison
- Institut Curie, PSL Research University, CNRS UMR 3244, 75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris Cedex 05, France
| | - Michelle Debatisse
- Institut Curie, PSL Research University, CNRS UMR 3244, 75248 Paris Cedex 05, France; Sorbonne Universités, UPMC Univ Paris 06, 75252 Paris Cedex 05, France.
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20
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Hosios AM, Fiske BP, Gui DY, Vander Heiden MG. Lack of Evidence for PKM2 Protein Kinase Activity. Mol Cell 2015; 59:850-7. [PMID: 26300261 PMCID: PMC4548833 DOI: 10.1016/j.molcel.2015.07.013] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 07/10/2015] [Accepted: 07/16/2015] [Indexed: 01/15/2023]
Abstract
The role of pyruvate kinase M2 (PKM2) in cell proliferation is controversial. A unique function of PKM2 proposed to be important for the proliferation of some cancer cells involves the direct activity of this enzyme as a protein kinase; however, a detailed biochemical characterization of this activity is lacking. Using [(32)P]-phosphoenolpyruvate (PEP) we examine the direct substrates of PKM2 using recombinant enzyme and in vitro systems where PKM2 is genetically deleted. Labeling of some protein species from [(32)P]-PEP can be observed; however, most were dependent on the presence of ADP, and none were dependent on the presence of PKM2. In addition, we also failed to observe PKM2-dependent transfer of phosphate from ATP directly to protein. These findings argue against a role for PKM2 as a protein kinase.
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Affiliation(s)
- Aaron M Hosios
- Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Brian P Fiske
- Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Dan Y Gui
- Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Matthew G Vander Heiden
- Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
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21
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East D, Fagiani F, Crosby J, Georgakopoulos N, Bertrand H, Schaap M, Fowkes A, Wells G, Campanella M. PMI: a ΔΨm independent pharmacological regulator of mitophagy. ACTA ACUST UNITED AC 2015; 21:1585-96. [PMID: 25455860 PMCID: PMC4245710 DOI: 10.1016/j.chembiol.2014.09.019] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 09/03/2014] [Accepted: 09/10/2014] [Indexed: 12/17/2022]
Abstract
Mitophagy is central to mitochondrial and cellular homeostasis and operates via the PINK1/Parkin pathway targeting mitochondria devoid of membrane potential (ΔΨm) to autophagosomes. Although mitophagy is recognized as a fundamental cellular process, selective pharmacologic modulators of mitophagy are almost nonexistent. We developed a compound that increases the expression and signaling of the autophagic adaptor molecule P62/SQSTM1 and forces mitochondria into autophagy. The compound, P62-mediated mitophagy inducer (PMI), activates mitophagy without recruiting Parkin or collapsing ΔΨm and retains activity in cells devoid of a fully functional PINK1/Parkin pathway. PMI drives mitochondria to a process of quality control without compromising the bio-energetic competence of the whole network while exposing just those organelles to be recycled. Thus, PMI circumvents the toxicity and some of the nonspecific effects associated with the abrupt dissipation of ΔΨm by ionophores routinely used to induce mitophagy and represents a prototype pharmacological tool to investigate the molecular mechanisms of mitophagy. PMI stabilizes Nrf2 and upregulates the dependent gene product P62 The increased P62 level drives mitochondrial autophagy PMI acts downstream of the PINK1/Parkin pathway leaving the ΔΨm intact
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Affiliation(s)
- Daniel A. East
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
| | - Francesca Fagiani
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
| | - James Crosby
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
| | - Nikolaos D. Georgakopoulos
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
- UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Hélène Bertrand
- UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Marjolein Schaap
- UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Adrian Fowkes
- UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Geoff Wells
- UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Michelangelo Campanella
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, Royal College Street, London NW1 0TU, UK
- UCL Consortium for Mitochondrial Research (CfMR), London WC1E 6BT, UK
- Corresponding author
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22
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Bueno M, Lai YC, Romero Y, Brands J, St Croix CM, Kamga C, Corey C, Herazo-Maya JD, Sembrat J, Lee JS, Duncan SR, Rojas M, Shiva S, Chu CT, Mora AL. PINK1 deficiency impairs mitochondrial homeostasis and promotes lung fibrosis. J Clin Invest 2014; 125:521-38. [PMID: 25562319 DOI: 10.1172/jci74942] [Citation(s) in RCA: 398] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Accepted: 11/13/2014] [Indexed: 12/17/2022] Open
Abstract
Although aging is a known risk factor for idiopathic pulmonary fibrosis (IPF), the pathogenic mechanisms that underlie the effects of advancing age remain largely unexplained. Some age-related neurodegenerative diseases have an etiology that is related to mitochondrial dysfunction. Here, we found that alveolar type II cells (AECIIs) in the lungs of IPF patients exhibit marked accumulation of dysmorphic and dysfunctional mitochondria. These mitochondrial abnormalities in AECIIs of IPF lungs were associated with upregulation of ER stress markers and were recapitulated in normal mice with advancing age in response to stimulation of ER stress. We found that impaired mitochondria in IPF and aging lungs were associated with low expression of PTEN-induced putative kinase 1 (PINK1). Knockdown of PINK1 expression in lung epithelial cells resulted in mitochondria depolarization and expression of profibrotic factors. Moreover, young PINK1-deficient mice developed similarly dysmorphic, dysfunctional mitochondria in the AECIIs and were vulnerable to apoptosis and development of lung fibrosis. Our data indicate that PINK1 deficiency results in swollen, dysfunctional mitochondria and defective mitophagy, and promotes fibrosis in the aging lung.
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23
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Parganlija D, Klinkenberg M, Domínguez-Bautista J, Hetzel M, Gispert S, Chimi MA, Dröse S, Mai S, Brandt U, Auburger G, Jendrach M. Loss of PINK1 impairs stress-induced autophagy and cell survival. PLoS One 2014; 9:e95288. [PMID: 24751806 PMCID: PMC3994056 DOI: 10.1371/journal.pone.0095288] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 03/26/2014] [Indexed: 11/25/2022] Open
Abstract
The mitochondrial kinase PINK1 and the ubiquitin ligase Parkin are participating in quality control after CCCP- or ROS-induced mitochondrial damage, and their dysfunction is associated with the development and progression of Parkinson's disease. Furthermore, PINK1 expression is also induced by starvation indicating an additional role for PINK1 in stress response. Therefore, the effects of PINK1 deficiency on the autophago-lysosomal pathway during stress were investigated. Under trophic deprivation SH-SY5Y cells with stable PINK1 knockdown showed downregulation of key autophagic genes, including Beclin, LC3 and LAMP-2. In good agreement, protein levels of LC3-II and LAMP-2 but not of LAMP-1 were reduced in different cell model systems with PINK1 knockdown or knockout after addition of different stressors. This downregulation of autophagic factors caused increased apoptosis, which could be rescued by overexpression of LC3 or PINK1. Taken together, the PINK1-mediated reduction of autophagic key factors during stress resulted in increased cell death, thus defining an additional pathway that could contribute to the progression of Parkinson's disease in patients with PINK1 mutations.
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Affiliation(s)
- Dajana Parganlija
- Experimental Neurology, Dept. of Neurology, Goethe University Medical School, Frankfurt/Main, Germany
| | - Michael Klinkenberg
- Experimental Neurology, Dept. of Neurology, Goethe University Medical School, Frankfurt/Main, Germany
| | - Jorge Domínguez-Bautista
- Experimental Neurology, Dept. of Neurology, Goethe University Medical School, Frankfurt/Main, Germany
| | - Miriam Hetzel
- Experimental Neurology, Dept. of Neurology, Goethe University Medical School, Frankfurt/Main, Germany
| | - Suzana Gispert
- Experimental Neurology, Dept. of Neurology, Goethe University Medical School, Frankfurt/Main, Germany
| | - Marthe A. Chimi
- Molecular Bioenergetics Group, Goethe University Medical School, Frankfurt/Main, Germany
| | - Stefan Dröse
- Molecular Bioenergetics Group, Goethe University Medical School, Frankfurt/Main, Germany
- Clinic of Anesthesiology, Intensive-Care Medicine and Pain Therapy, Goethe-University Hospital, Frankfurt am Main, Germany
| | - Sören Mai
- Kinematic Cell Research Group, Institute for Cell Biology and Neuroscience, Center of Excellence Frankfurt: Macromolecular Complexes, Goethe University, Frankfurt/Main, Germany
| | - Ulrich Brandt
- Molecular Bioenergetics Group, Goethe University Medical School, Frankfurt/Main, Germany
| | - Georg Auburger
- Experimental Neurology, Dept. of Neurology, Goethe University Medical School, Frankfurt/Main, Germany
| | - Marina Jendrach
- Experimental Neurology, Dept. of Neurology, Goethe University Medical School, Frankfurt/Main, Germany
- * E-mail:
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24
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Sanchez G, Varaschin RK, Büeler H, Marcogliese PC, Park DS, Trudeau LE. Unaltered striatal dopamine release levels in young Parkin knockout, Pink1 knockout, DJ-1 knockout and LRRK2 R1441G transgenic mice. PLoS One 2014; 9:e94826. [PMID: 24733019 PMCID: PMC3986353 DOI: 10.1371/journal.pone.0094826] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Accepted: 03/19/2014] [Indexed: 01/09/2023] Open
Abstract
Parkinson's disease (PD) is one of the most prevalent neurodegenerative brain diseases; it is accompanied by extensive loss of dopamine (DA) neurons of the substantia nigra that project to the putamen, leading to impaired motor functions. Several genes have been associated with hereditary forms of the disease and transgenic mice have been developed by a number of groups to produce animal models of PD and to explore the basic functions of these genes. Surprisingly, most of the various mouse lines generated such as Parkin KO, Pink1 KO, DJ-1 KO and LRRK2 transgenic have been reported to lack degeneration of nigral DA neuron, one of the hallmarks of PD. However, modest impairments of motor behavior have been reported, suggesting the possibility that the models recapitulate at least some of the early stages of PD, including early dysfunction of DA axon terminals. To further evaluate this possibility, here we provide for the first time a systematic comparison of DA release in four different mouse lines, examined at a young age range, prior to potential age-dependent compensations. Using fast scan cyclic voltammetry in striatal sections prepared from young, 6–8 weeks old mice, we examined sub-second DA overflow evoked by single pulses and action potential trains. Unexpectedly, none of the models displayed any dysfunction of DA overflow or reuptake. These results, compatible with the lack of DA neuron loss in these models, suggest that molecular dysfunctions caused by the absence or mutation of these individual genes are not sufficient to perturb the function and survival of mouse DA neurons.
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Affiliation(s)
- Gonzalo Sanchez
- Departments of pharmacology and neurosciences, Central Nervous System Research Group, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Rafael K. Varaschin
- Departments of pharmacology and neurosciences, Central Nervous System Research Group, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Hansruedi Büeler
- School of Life Sciences and Technology, Harbin Institute of Technology, Harbin, China
| | - Paul C. Marcogliese
- Department of cellular and molecular medicine, Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - David S. Park
- Department of cellular and molecular medicine, Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Louis-Eric Trudeau
- Departments of pharmacology and neurosciences, Central Nervous System Research Group, Faculty of Medicine, Université de Montréal, Montreal, Canada
- * E-mail:
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25
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Belfield C, Queenan C, Rao H, Kitamura K, Walworth NC. The oxidative stress responsive transcription factor Pap1 confers DNA damage resistance on checkpoint-deficient fission yeast cells. PLoS One 2014; 9:e89936. [PMID: 24587136 PMCID: PMC3934961 DOI: 10.1371/journal.pone.0089936] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/28/2014] [Indexed: 11/19/2022] Open
Abstract
Eukaryotic cells invoke mechanisms to promote survival when confronted with cellular stress or damage to the genome. The protein kinase Chk1 is an integral and conserved component of the DNA damage response pathway. Mutation or inhibition of Chk1 results in mitotic death when cells are exposed to DNA damage. Oxidative stress activates a pathway that results in nuclear accumulation of the bZIP transcription factor Pap1. We report the novel finding that fission yeast Pap1 confers resistance to drug- and non-drug-induced DNA damage even when the DNA damage checkpoint is compromised. Multi-copy expression of Pap1 restores growth to chk1-deficient cells exposed to camptothecin or hydroxyurea. Unexpectedly, increased Pap1 expression also promotes survival of chk1-deficient cells with mutations in genes encoding DNA ligase (cdc17) or DNA polymerase δ (cdc6), but not DNA replication initiation mutants. The ability of Pap1 to confer resistance to DNA damage was not specific to chk1 mutants, as it also improved survival of rad1- and rad9-deficient cells in the presence of CPT. To confer resistance to DNA damage Pap1 must localize to the nucleus and be transcriptionally active.
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Affiliation(s)
- Carrie Belfield
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
- Graduate Program in Cellular and Molecular Pharmacology, Rutgers Graduate School of Biomedical Sciences, Piscataway, New Jersey, United States of America
| | - Craig Queenan
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Hui Rao
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Kenji Kitamura
- Center for Gene Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Nancy C. Walworth
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
- Graduate Program in Cellular and Molecular Pharmacology, Rutgers Graduate School of Biomedical Sciences, Piscataway, New Jersey, United States of America
- Member, Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey, United States of America
- * E-mail:
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26
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Ashraf S, Gee HY, Woerner S, Xie LX, Vega-Warner V, Lovric S, Fang H, Song X, Cattran DC, Avila-Casado C, Paterson AD, Nitschké P, Bole-Feysot C, Cochat P, Esteve-Rudd J, Haberberger B, Allen SJ, Zhou W, Airik R, Otto EA, Barua M, Al-Hamed MH, Kari JA, Evans J, Bierzynska A, Saleem MA, Böckenhauer D, Kleta R, El Desoky S, Hacihamdioglu DO, Gok F, Washburn J, Wiggins RC, Choi M, Lifton RP, Levy S, Han Z, Salviati L, Prokisch H, Williams DS, Pollak M, Clarke CF, Pei Y, Antignac C, Hildebrandt F. ADCK4 mutations promote steroid-resistant nephrotic syndrome through CoQ10 biosynthesis disruption. J Clin Invest 2013; 123:5179-89. [PMID: 24270420 DOI: 10.1172/jci69000] [Citation(s) in RCA: 235] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 09/06/2013] [Indexed: 12/14/2022] Open
Abstract
Identification of single-gene causes of steroid-resistant nephrotic syndrome (SRNS) has furthered the understanding of the pathogenesis of this disease. Here, using a combination of homozygosity mapping and whole human exome resequencing, we identified mutations in the aarF domain containing kinase 4 (ADCK4) gene in 15 individuals with SRNS from 8 unrelated families. ADCK4 was highly similar to ADCK3, which has been shown to participate in coenzyme Q10 (CoQ10) biosynthesis. Mutations in ADCK4 resulted in reduced CoQ10 levels and reduced mitochondrial respiratory enzyme activity in cells isolated from individuals with SRNS and transformed lymphoblasts. Knockdown of adck4 in zebrafish and Drosophila recapitulated nephrotic syndrome-associated phenotypes. Furthermore, ADCK4 was expressed in glomerular podocytes and partially localized to podocyte mitochondria and foot processes in rat kidneys and cultured human podocytes. In human podocytes, ADCK4 interacted with members of the CoQ10 biosynthesis pathway, including COQ6, which has been linked with SRNS and COQ7. Knockdown of ADCK4 in podocytes resulted in decreased migration, which was reversed by CoQ10 addition. Interestingly, a patient with SRNS with a homozygous ADCK4 frameshift mutation had partial remission following CoQ10 treatment. These data indicate that individuals with SRNS with mutations in ADCK4 or other genes that participate in CoQ10 biosynthesis may be treatable with CoQ10.
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27
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Nath K, Poudyal RS, Eom JS, Park YS, Zulfugarov IS, Mishra SR, Tovuu A, Ryoo N, Yoon HS, Nam HG, An G, Jeon JS, Lee CH. Loss-of-function of OsSTN8 suppresses the photosystem II core protein phosphorylation and interferes with the photosystem II repair mechanism in rice (Oryza sativa). Plant J 2013; 76:675-86. [PMID: 24103067 DOI: 10.1111/tpj.12331] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 08/07/2013] [Accepted: 09/02/2013] [Indexed: 05/10/2023]
Abstract
STN8 kinase is involved in photosystem II (PSII) core protein phosphorylation (PCPP). To examine the role of PCPP in PSII repair during high light (HL) illumination, we characterized a T-DNA insertional knockout mutant of the rice (Oryza sativa) STN8 gene. In this osstn8 mutant, PCPP was significantly suppressed, and the grana were thin and elongated. Upon HL illumination, PSII was strongly inactivated in the mutants, but the D1 protein was degraded more slowly than in wild-type, and mobilization of the PSII supercomplexes from the grana to the stromal lamellae for repair was also suppressed. In addition, higher accumulation of reactive oxygen species and preferential oxidation of PSII reaction center core proteins in thylakoid membranes were observed in the mutants during HL illumination. Taken together, our current data show that the absence of STN8 is sufficient to abolish PCPP in osstn8 mutants and to produce all of the phenotypes observed in the double mutant of Arabidopsis, indicating the essential role of STN8-mediated PCPP in PSII repair.
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Affiliation(s)
- Krishna Nath
- Department of Molecular Biology, Pusan National University, Busan, 609-735, Korea; Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu, 711-873, Korea
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28
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Siddall HK, Yellon DM, Ong SB, Mukherjee UA, Burke N, Hall AR, Angelova PR, Ludtmann MHR, Deas E, Davidson SM, Mocanu MM, Hausenloy DJ. Loss of PINK1 increases the heart's vulnerability to ischemia-reperfusion injury. PLoS One 2013; 8:e62400. [PMID: 23638067 PMCID: PMC3639249 DOI: 10.1371/journal.pone.0062400] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 03/21/2013] [Indexed: 12/21/2022] Open
Abstract
Objectives Mutations in PTEN inducible kinase-1 (PINK1) induce mitochondrial dysfunction in dopaminergic neurons resulting in an inherited form of Parkinson’s disease. Although PINK1 is present in the heart its exact role there is unclear. We hypothesized that PINK1 protects the heart against acute ischemia reperfusion injury (IRI) by preventing mitochondrial dysfunction. Methods and Results Over-expressing PINK1 in HL-1 cardiac cells reduced cell death following simulated IRI (29.2±5.2% PINK1 versus 49.0±2.4% control; N = 320 cells/group P<0.05), and delayed the onset of mitochondrial permeability transition pore (MPTP) opening (by 1.3 fold; P<0.05). Hearts excised from PINK1+/+, PINK1+/− and PINK1−/− mice were subjected to 35 minutes regional ischemia followed by 30 minutes reperfusion. Interestingly, myocardial infarct size was increased in PINK1−/− hearts compared to PINK1+/+ hearts with an intermediate infarct size in PINK1+/− hearts (25.1±2.0% PINK1+/+, 38.9±3.4% PINK1+/− versus 51.5±4.3% PINK1−/− hearts; N>5 animals/group; P<0.05). Cardiomyocytes isolated from PINK1−/− hearts had a lower resting mitochondrial membrane potential, had inhibited mitochondrial respiration, generated more oxidative stress during simulated IRI, and underwent rigor contracture more rapidly in response to an uncoupler when compared to PINK1+/+ cells suggesting mitochondrial dysfunction in hearts deficient in PINK1. Conclusions We show that the loss of PINK1 increases the heart's vulnerability to ischemia-reperfusion injury. This may be due, in part, to increased mitochondrial dysfunction. These findings implicate PINK1 as a novel target for cardioprotection.
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Affiliation(s)
- Hilary K. Siddall
- The Hatter Cardiovascular Institute, University College London, London, United Kingdom
| | - Derek M. Yellon
- The Hatter Cardiovascular Institute, University College London, London, United Kingdom
| | - Sang-Bing Ong
- Department of Clinical Sciences, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysia
| | - Uma A. Mukherjee
- The Hatter Cardiovascular Institute, University College London, London, United Kingdom
| | - Niall Burke
- The Hatter Cardiovascular Institute, University College London, London, United Kingdom
| | - Andrew R. Hall
- The Hatter Cardiovascular Institute, University College London, London, United Kingdom
| | - Plamena R. Angelova
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Marthe H. R. Ludtmann
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Emma Deas
- Department of Molecular Neuroscience, University College London Institute of Neurology, London, United Kingdom
| | - Sean M. Davidson
- The Hatter Cardiovascular Institute, University College London, London, United Kingdom
| | - Mihaela M. Mocanu
- The Hatter Cardiovascular Institute, University College London, London, United Kingdom
| | - Derek J. Hausenloy
- The Hatter Cardiovascular Institute, University College London, London, United Kingdom
- * E-mail:
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Smith GA, Isacson O, Dunnett SB. The search for genetic mouse models of prodromal Parkinson's disease. Exp Neurol 2012; 237:267-73. [PMID: 22819262 DOI: 10.1016/j.expneurol.2012.06.035] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 06/21/2012] [Accepted: 06/30/2012] [Indexed: 01/13/2023]
Abstract
Parkinson's disease is characterized and diagnosed by bradykinetic motor symptoms caused by the loss of dopamine neurons in the substantia nigra. The pathological and non-motor behavioral changes that occur prior to degeneration are less well characterized, although changes in gait, olfaction and cognition have been recognized in familial Parkinson's disease subjects. Gene mutations associated familial Parkinson's disease give rise to mitochondrial changes, altered energy homeostasis and intracellular trafficking deficits, and these can be modeled in transgenic mice. Here we discuss the recent finding of prodromal behavioral disturbances in a PINK1 deficient mouse that manifest prior to dopaminergic cell death and correlate to 5-HT fiber losses and mitochondrial morphological changes. We discuss the representation of the PINK1 deficient mouse and other genetic models to accurately recapitulate early Parkinson's disease. Prodromal symptoms and underlying pathology modeled in mice and cell lines from human subjects may have wide implications for earlier diagnosis. Current and emerging therapies need to be tailored to target both early cognitive and late stage motor symptoms.
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Affiliation(s)
- Gaynor A Smith
- Neuroregeneration Laboratories, McLean Hospital/Harvard Medical School, MA 02478, USA.
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30
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Kirsanov KI, Lesovaya EA, Sidorov RA, Belitskiĭ GA, Yakubovskaia MG. [Analysis of blastomogenic activity of mammal carcinogens in Drosophila using the wts(P4) allele and RNA interference-induced p53 silencing]. Genetika 2011; 47:466-474. [PMID: 21675235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The test for somatic mutagenesis and recombination in Drosophila is one of the widely used approaches for determination of possible carcinogenic effects of chemical compounds. The use of heterozygotes for mutant tumor suppressor gene wts enables more direct evaluation of the blastomogenic effects of chemical compounds, by tumor formation in the adult flies. This study presents evaluation of the SMART effectiveness upon the use of Drosophila heterozygotes for the wts(P4) gene, first included into the test system. The increase of the test resolution capacity compared to the literature data for the wts(P2) allele was observed. Using wts(P4) heterozygotes, a total of 20 carcinogenic compounds, and their slightly carcinogenic and noncarcinogenic analogs were tested. Specificity of the method was about 100%, and sensitivity depended on the type of the agent tested. The latter was absolute for the direct action carcinogens, with respect to carcinogens, requiring the metabolic activation. The sensitivity was elective and was limited by the presence of the enzymes capable of activating of these compounds. To increase the test sensitivity, the RNA interference-mediated silencing of the Drosophila p53 functional activity was successfully applied. Moreover, the frequency of wts tumor induction considerably increased both in spontaneous and induced mutagenesis conditions.
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Akundi RS, Huang Z, Eason J, Pandya JD, Zhi L, Cass WA, Sullivan PG, Büeler H. Increased mitochondrial calcium sensitivity and abnormal expression of innate immunity genes precede dopaminergic defects in Pink1-deficient mice. PLoS One 2011; 6:e16038. [PMID: 21249202 PMCID: PMC3020954 DOI: 10.1371/journal.pone.0016038] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 12/05/2010] [Indexed: 11/24/2022] Open
Abstract
Background PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca2+ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1−/− mice. Methods and Findings Purified brain mitochondria of Pink1−/− mice showed impaired Ca2+ storage capacity, resulting in increased Ca2+ induced mitochondrial permeability transition (mPT) that was rescued by cyclosporine A. A subpopulation of neurons in the substantia nigra of Pink1−/− mice accumulated phospho-c-Jun, showing that Jun N-terminal kinase (JNK) activity is increased. Pink1−/− mice 6 months and older displayed reduced DA levels associated with increased DA turnover. Moreover, Pink1−/− mice had increased levels of IL-1β, IL-12 and IL-10 in the striatum after peripheral challenge with lipopolysaccharide (LPS), and Pink1−/− embryonic fibroblasts showed decreased basal and inflammatory cytokine-induced nuclear factor kappa-β (NF-κB) activity. Quantitative transcriptional profiling in the striatum revealed that Pink1−/− mice differentially express genes that (i) are upregulated in animals with experimentally induced dopaminergic lesions, (ii) regulate innate immune responses and/or apoptosis and (iii) promote axonal regeneration and sprouting. Conclusions Increased mitochondrial Ca2+ sensitivity and JNK activity are early defects in Pink1−/− mice that precede reduced DA levels and abnormal DA homeostasis and may contribute to neuronal dysfunction in familial PD. Differential gene expression in the nigrostriatal system of Pink1−/− mice supports early dopaminergic dysfunction and shows that Pink1 deletion causes aberrant expression of genes that regulate innate immune responses. While some differentially expressed genes may mitigate neurodegeneration, increased LPS-induced brain cytokine expression and impaired cytokine-induced NF-κB activation may predispose neurons of Pink1−/− mice to inflammation and injury-induced cell death.
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Affiliation(s)
- Ravi S. Akundi
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Zhenyu Huang
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Joshua Eason
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Jignesh D. Pandya
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Lianteng Zhi
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Wayne A. Cass
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Patrick G. Sullivan
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- Spinal Cord and Brain Injury Research Center, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
| | - Hansruedi Büeler
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America
- * E-mail:
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Jeong YJ, Shang Y, Kim BH, Kim SY, Song JH, Lee JS, Lee MM, Li J, Nam KH. BAK7 displays unequal genetic redundancy with BAK1 in brassinosteroid signaling and early senescence in Arabidopsis. Mol Cells 2010; 29:259-66. [PMID: 20108170 DOI: 10.1007/s10059-010-0024-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 10/13/2009] [Accepted: 11/18/2009] [Indexed: 10/19/2022] Open
Abstract
BRI1-Associated kinase 1 (BAK1), a five leucine-rich-repeat containing receptor-like serine/threonine kinase, has been shown to have dual functions: mediating brassinosteroid (BR) signaling and acting in the BR-independent plant defense response. Sequence analysis has revealed that BAK1 has two homologs, BAK7 and BAK8. Because BAK8 deviates from the canonical RD kinase motif, we focused on the functional analysis of BAK7. The expression pattern and tissues in which BAK7 appeared partially overlapped with those observed for BAK1. Expression levels of BAK7 increased in the bak1 mutant. Overexpression of BAK7 rescued the bri1 mutant phenotype, indicating that BAK7 can compensate for BAK1 in BR-mediated processes, especially in the absence of BAK1. However, root and hypocotyl elongation patterns of transgenic plants overexpressing BAK1 or BAK7 appeared to be different from the patterns observed in a BRI1 overexpressor. Furthermore, the sensitivity of transgenic plants overexpressing BAK7 to brassinazole, a biosynthetic inhibitor of brassinolide (BL), did not change compared to that of wild-type plants. In addition, we generated transgenic plants expressing BAK7 RNA interference constructs and found severe growth retardation and early senescence in these lines. Taken together, these results suggest that BAK7 is a component of the BR signaling pathway, with varying degrees of genetic redundancy with BAK1, and that it affects plant growth via BL-independent pathways in vivo.
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Affiliation(s)
- Yu Jeong Jeong
- Division of Biological Science, Sookmyung Women's University, Seoul, 140-742, Korea
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Sandebring A, Thomas KJ, Beilina A, van der Brug M, Cleland MM, Ahmad R, Miller DW, Zambrano I, Cowburn RF, Behbahani H, Cedazo-Mínguez A, Cookson MR. Mitochondrial alterations in PINK1 deficient cells are influenced by calcineurin-dependent dephosphorylation of dynamin-related protein 1. PLoS One 2009; 4:e5701. [PMID: 19492085 PMCID: PMC2683574 DOI: 10.1371/journal.pone.0005701] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 04/27/2009] [Indexed: 01/17/2023] Open
Abstract
PTEN-induced novel kinase 1 (PINK1) mutations are associated with autosomal recessive parkinsonism. Previous studies have shown that PINK1 influences both mitochondrial function and morphology although it is not clearly established which of these are primary events and which are secondary. Here, we describe a novel mechanism linking mitochondrial dysfunction and alterations in mitochondrial morphology related to PINK1. Cell lines were generated by stably transducing human dopaminergic M17 cells with lentiviral constructs that increased or knocked down PINK1. As in previous studies, PINK1 deficient cells have lower mitochondrial membrane potential and are more sensitive to the toxic effects of mitochondrial complex I inhibitors. We also show that wild-type PINK1, but not recessive mutant or kinase dead versions, protects against rotenone-induced mitochondrial fragmentation whereas PINK1 deficient cells show lower mitochondrial connectivity. Expression of dynamin-related protein 1 (Drp1) exaggerates PINK1 deficiency phenotypes and Drp1 RNAi rescues them. We also show that Drp1 is dephosphorylated in PINK1 deficient cells due to activation of the calcium-dependent phosphatase calcineurin. Accordingly, the calcineurin inhibitor FK506 blocks both Drp1 dephosphorylation and loss of mitochondrial integrity in PINK1 deficient cells but does not fully rescue mitochondrial membrane potential. We propose that alterations in mitochondrial connectivity in this system are secondary to functional effects on mitochondrial membrane potential.
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Affiliation(s)
- Anna Sandebring
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, Maryland, United States of America
- Alzheimer's Disease Research Center, Karolinska Institutet, Stockholm, Sweden
| | - Kelly Jean Thomas
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, Maryland, United States of America
| | - Alexandra Beilina
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, Maryland, United States of America
| | - Marcel van der Brug
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, Maryland, United States of America
| | - Megan M. Cleland
- Surgical Neurology Branch, National Institute of Neurological Diseases and Stroke, Bethesda, Maryland, United States of America
| | - Rili Ahmad
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, Maryland, United States of America
| | - David W. Miller
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, Maryland, United States of America
| | - Ibardo Zambrano
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, Maryland, United States of America
| | - Richard F. Cowburn
- Alzheimer's Disease Research Center, Karolinska Institutet, Stockholm, Sweden
| | - Homira Behbahani
- Alzheimer's Disease Research Center, Karolinska Institutet, Stockholm, Sweden
| | | | - Mark R. Cookson
- Laboratory of Neurogenetics, National Institute on Aging, Bethesda, Maryland, United States of America
- * E-mail:
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Gandhi S, Wood-Kaczmar A, Yao Z, Plun-Favreau H, Deas E, Klupsch K, Downward J, Latchman DS, Tabrizi SJ, Wood NW, Duchen MR, Abramov AY. PINK1-associated Parkinson's disease is caused by neuronal vulnerability to calcium-induced cell death. Mol Cell 2009; 33:627-38. [PMID: 19285945 PMCID: PMC2724101 DOI: 10.1016/j.molcel.2009.02.013] [Citation(s) in RCA: 505] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 09/01/2008] [Accepted: 02/20/2009] [Indexed: 12/21/2022]
Abstract
Mutations in PINK1 cause autosomal recessive Parkinson's disease. PINK1 is a mitochondrial kinase of unknown function. We investigated calcium homeostasis and mitochondrial function in PINK1-deficient mammalian neurons. We demonstrate physiologically that PINK1 regulates calcium efflux from the mitochondria via the mitochondrial Na(+)/Ca(2+) exchanger. PINK1 deficiency causes mitochondrial accumulation of calcium, resulting in mitochondrial calcium overload. We show that calcium overload stimulates reactive oxygen species (ROS) production via NADPH oxidase. ROS production inhibits the glucose transporter, reducing substrate delivery and causing impaired respiration. We demonstrate that impaired respiration may be restored by provision of mitochondrial complex I and II substrates. Taken together, reduced mitochondrial calcium capacity and increased ROS lower the threshold of opening of the mitochondrial permeability transition pore (mPTP) such that physiological calcium stimuli become sufficient to induce mPTP opening in PINK1-deficient cells. Our findings propose a mechanism by which PINK1 dysfunction renders neurons vulnerable to cell death.
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Affiliation(s)
- Sonia Gandhi
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, UK
- Medical Molecular Biology Unit, Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
| | - Alison Wood-Kaczmar
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Zhi Yao
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Helene Plun-Favreau
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Emma Deas
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Kristina Klupsch
- Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - Julian Downward
- Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
| | - David S. Latchman
- Medical Molecular Biology Unit, Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
- Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Sarah J. Tabrizi
- Department of Neurodegenerative Disease, Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Nicholas W. Wood
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Michael R. Duchen
- Department of Physiology, University College London, London WC1E 6BT, UK
| | - Andrey Y. Abramov
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, UK
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Da Silva Morais A, Lebrun V, Abarca-Quinones J, Brichard S, Hue L, Guigas B, Viollet B, Leclercq IA. Prevention of steatohepatitis by pioglitazone: implication of adiponectin-dependent inhibition of SREBP-1c and inflammation. J Hepatol 2009; 50:489-500. [PMID: 19155087 DOI: 10.1016/j.jhep.2008.10.027] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Revised: 10/04/2008] [Accepted: 10/11/2008] [Indexed: 01/07/2023]
Abstract
BACKGROUND/AIMS Peroxisome proliferator-activated receptor gamma (PPARgamma) agonist drugs, like pioglitazone (PGZ), are proposed as treatments for steatohepatitis. Their mechanisms of action remain ill-clarified. METHODS To test the hypothesis that PGZ improves steatohepatitis through adiponectin-dependent stimulation of AMPK and/or PPARalpha, mice lacking adiponectin (Adipo(-/-)) or the AMPKalpha1 catalytic subunit (AMPKalpha1(-/-)) or wild-type (Wt) mice were fed the methionine and choline deficient (MCD) diet, supplemented or not with PGZ. RESULTS In Wt mice, PGZ increased circulating levels of adiponectin and reduced the severity of MCD-induced steatohepatitis but there was no evidence of activation of AMPK or PPARalpha and their downstream targets. By contrast, PGZ completely repressed nuclear translocation of SREBP-1c, a key transcription factor for de novo lipogenesis. This effect was lacking in Adipo(-/-) mice in which PGZ failed to prevent steatohepatitis. Surprisingly, AMPKalpha1(-/-) mice were resistant to MCD-induced steatohepatitis, a status also associated with repression of SREBP-1c. CONCLUSIONS The preventive effect of PGZ on MCD-induced steatohepatitis depends on adiponectin upregulation but apparently does not involve AMPK or PPARalpha activation. The inhibition of SREBP-1c and dependent repression of lipogenesis are likely to participate in this effect. The mechanisms by which PGZ and adiponectin control SREBP-1c and inflammation remain to be elucidated.
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Affiliation(s)
- Alain Da Silva Morais
- Laboratoire de Gastro-entérologie, Université Catholique de Louvain, GAEN 53/79, Brussels, Belgium
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Abstract
The effect of pyruvate dehydrogenase kinase-4 (PDK4) deficiency on glucose homeostasis was studied in mice fed a high-fat diet. Expression of PDK4 was greatly increased in skeletal muscle and diaphragm but not liver and kidney of wild-type mice fed the high-fat diet. Wild-type and PDK4(-/-) mice consumed similar amounts of the diet and became equally obese. Insulin resistance developed in both groups. Nevertheless, fasting blood glucose levels were lower, glucose tolerance was slightly improved, and insulin sensitivity was slightly greater in the PDK4(-/-) mice compared with wild-type mice. When the mice were killed in the fed state, the actual activity of the pyruvate dehydrogenase complex (PDC) was higher in the skeletal muscle and diaphragm but not in the liver and kidney of PDK4(-/-) mice compared with wild-type mice. When the mice were killed after overnight fasting, the actual PDC activity was higher only in the kidney of PDK4(-/-) mice compared with wild-type mice. The concentrations of gluconeogenic substrates were lower in the blood of PDK4(-/-) mice compared with wild-type mice, consistent with reduced formation in peripheral tissues. Diaphragms isolated from PDK4(-/-) mice oxidized glucose faster and fatty acids slower than diaphragms from wild-type mice. Fatty acid oxidation inhibited glucose oxidation by diaphragms from wild-type but not PDK4(-/-) mice. NEFA, ketone bodies, and branched-chain amino acids were elevated more in PDK4(-/-) mice, consistent with slower rates of oxidation. These findings show that PDK4 deficiency lowers blood glucose and slightly improves glucose tolerance and insulin sensitivity in mice with diet-induced obesity.
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Affiliation(s)
- Nam Ho Jeoung
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine and the Research Service, Richard Roudebush Veterans Affairs Medical Center, Indianapolis, IN 46202, USA
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Zhou J, Wulfkuhle J, Zhang H, Gu P, Yang Y, Deng J, Margolick JB, Liotta LA, Petricoin E, Zhang Y. Activation of the PTEN/mTOR/STAT3 pathway in breast cancer stem-like cells is required for viability and maintenance. Proc Natl Acad Sci U S A 2007; 104:16158-63. [PMID: 17911267 PMCID: PMC2042178 DOI: 10.1073/pnas.0702596104] [Citation(s) in RCA: 520] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Side-population (SP) cells within cancers and cell lines are rare cell populations known to enrich cancer stem-like cells. In this study, we characterized SP cells from the human breast cancer cell line MCF7 as a model for cancer stem-like cells. Compared with non-SP cells, MCF7 SP cells had higher colony-formation ability in vitro and greater tumorigenicity in vivo, suggesting that MCF7 SP cells enrich cancer stem-like cells. cDNA microarray analysis of the SP cells indicated higher expression of ATP-binding cassette transporters and genes involved in quiescence, which were confirmed by quantitative RT-PCR and flow cytometry cell cycle analysis. To identify signal pathways important for cancer stem-like cells, we analyzed cDNA microarray data and identified nine pathways that were altered in the SP cells. To analyze the protein signaling networks, we used reverse-phase signaling pathway protein microarray technology and identified three signaling proteins that are significantly different between MCF7 SP and non-SP cells. Notably, signaling of phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR), signal transduction and activator of transcription (STAT3), and phosphatase and tensin homolog (PTEN) was confirmed to be critical for MCF7 SP cell survival and proliferation by pathway specific inhibitors, selected gene knockdown, and in vivo tumorigenicity assay. The STAT3 pathway was found to be positively regulated by mTOR signaling, whereas PTEN served as a negative regulator of both STAT3 and mTOR signaling. This study suggests the existence of prosurvival signaling pathways critical for cancer stem-like cell maintenance, which could be selectively targeted for inhibiting cancer stem-like cells for improved treatment.
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Affiliation(s)
- Jiangbing Zhou
- Department of *Molecular Microbiology and Immunology, Bloomberg School of Public Health, and
| | - Julia Wulfkuhle
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110
| | - Hao Zhang
- Department of *Molecular Microbiology and Immunology, Bloomberg School of Public Health, and
| | - Peihua Gu
- Department of *Molecular Microbiology and Immunology, Bloomberg School of Public Health, and
| | - Yanqin Yang
- Department of Ophthalmology, School of Medicine, The Johns Hopkins University, Baltimore, MD 21205; and
| | - Jianghong Deng
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110
| | - Joseph B. Margolick
- Department of *Molecular Microbiology and Immunology, Bloomberg School of Public Health, and
| | - Lance A. Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110
| | - Emanuel Petricoin
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110
| | - Ying Zhang
- Department of *Molecular Microbiology and Immunology, Bloomberg School of Public Health, and
- To whom correspondence should be addressed. E-mail:
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Jin H, Yan Z, Nam KH, Li J. Allele-specific suppression of a defective brassinosteroid receptor reveals a physiological role of UGGT in ER quality control. Mol Cell 2007; 26:821-30. [PMID: 17588517 PMCID: PMC1948852 DOI: 10.1016/j.molcel.2007.05.015] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 04/11/2007] [Accepted: 05/16/2007] [Indexed: 10/23/2022]
Abstract
UDP-glucose:glycoprotein glucosyltransferase (UGGT) is a presumed folding sensor of protein quality control in the endoplasmic reticulum (ER). Previous biochemical studies with nonphysiological substrates revealed that UGGT can glucosylate nonnative glycoproteins by recognizing subtle folding defects; however, its physiological function remains undefined. Here, we show that mutations in the Arabidopsis EBS1 gene suppressed the growth defects of a brassinosteroid (BR) receptor mutant, bri1-9, in an allele-specific manner by restoring its BR sensitivity. Using a map-based cloning strategy, we discovered that EBS1 encodes the Arabidopsis homolog of UGGT. We demonstrated that bri1-9 is retained in the ER through interactions with several ER chaperones and that ebs1 mutations significantly reduce the stringency of the retention-based ER quality control, allowing export of the structurally imperfect yet biochemically competent bri1-9 to the cell surface for BR perception. Thus, our discovery provides genetic support for a physiological role of UGGT in high-fidelity ER quality control.
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Affiliation(s)
- Hua Jin
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA
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Moniz S, Veríssimo F, Matos P, Brazão R, Silva E, Kotelevets L, Kotevelets L, Chastre E, Gespach C, Jordan P. Protein kinase WNK2 inhibits cell proliferation by negatively modulating the activation of MEK1/ERK1/2. Oncogene 2007; 26:6071-81. [PMID: 17667937 DOI: 10.1038/sj.onc.1210706] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The recently identified subfamily of WNK protein kinases is characterized by a unique sequence variation in the catalytic domain and four related human WNK genes were identified. Here, we describe the cloning and functional analysis of the human family member WNK2. We show that the depletion of endogenous WNK2 expression by RNA interference in human cervical HeLa cancer cells led to the activation of the extracellular signal-regulated kinase (ERK)1/2 mitogen-activated protein kinases but, in contrast to the depletion of WNK1, had no effect on ERK5. Furthermore, expression of a kinase-dead WNK2-K207M mutant also activated ERK1/2 suggesting that WNK2 catalytic activity is required. Depletion of WNK2 expression increased G1/S progression and potentiated the cellular response to low epidermal growth factor concentrations. The molecular mechanism of ERK1/2 activation in WNK2-depleted cells lies downstream of the Raf kinases and involves MEK1 phosphorylation at serine 298 in both HeLa and HT29 colon cancer cells. This modification is linked to the upregulation of MEK1 activity toward ERK1/2. Together, these results provide evidence that WNK2 is involved in the modulation of growth factor-induced cancer cell proliferation through the MEK1/ERK1/2 pathway. The data identify WNK2 as a candidate tumor suppressor gene and suggest a coordinated activity of WNK kinases in the regulation of cell proliferation.
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Affiliation(s)
- S Moniz
- Centre of Human Genetics, Instituto Nacional de Saúde Dr Ricardo Jorge, Lisbon, Portugal
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40
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Kitada T, Pisani A, Porter DR, Yamaguchi H, Tscherter A, Martella G, Bonsi P, Zhang C, Pothos EN, Shen J. Impaired dopamine release and synaptic plasticity in the striatum of PINK1-deficient mice. Proc Natl Acad Sci U S A 2007; 104:11441-6. [PMID: 17563363 PMCID: PMC1890561 DOI: 10.1073/pnas.0702717104] [Citation(s) in RCA: 390] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Parkinson's disease (PD) is characterized by the selective vulnerability of the nigrostriatal dopaminergic circuit. Recently, loss-of-function mutations in the PTEN-induced kinase 1 (PINK1) gene have been linked to early-onset PD. How PINK1 deficiency causes dopaminergic dysfunction and degeneration in PD patients is unknown. Here, we investigate the physiological role of PINK1 in the nigrostriatal dopaminergic circuit through the generation and multidisciplinary analysis of PINK1(-/-) mutant mice. We found that numbers of dopaminergic neurons and levels of striatal dopamine (DA) and DA receptors are unchanged in PINK1(-/-) mice. Amperometric recordings, however, revealed decreases in evoked DA release in striatal slices and reductions in the quantal size and release frequency of catecholamine in dissociated chromaffin cells. Intracellular recordings of striatal medium spiny neurons, the major dopaminergic target, showed specific impairments of corticostriatal long-term potentiation and long-term depression in PINK1(-/-) mice. Consistent with a decrease in evoked DA release, these striatal plasticity impairments could be rescued by either DA receptor agonists or agents that increase DA release, such as amphetamine or l-dopa. These results reveal a critical role for PINK1 in DA release and striatal synaptic plasticity in the nigrostriatal circuit and suggest that altered dopaminergic physiology may be a pathogenic precursor to nigrostriatal degeneration.
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Affiliation(s)
- Tohru Kitada
- *Center for Neurologic Diseases, Brigham and Women's Hospital, Program in Neuroscience, Harvard Medical School, Boston, MA 02115
| | - Antonio Pisani
- Department of Neuroscience, University of Rome Tor Vergata and Fondazione Santa Lucia, 00133 Rome, Italy; and
| | - Douglas R. Porter
- Department of Pharmacology and Experimental Therapeutics and Program in Neuroscience, Tufts University School of Medicine, Boston, MA 02111
| | - Hiroo Yamaguchi
- *Center for Neurologic Diseases, Brigham and Women's Hospital, Program in Neuroscience, Harvard Medical School, Boston, MA 02115
| | - Anne Tscherter
- Department of Neuroscience, University of Rome Tor Vergata and Fondazione Santa Lucia, 00133 Rome, Italy; and
| | - Giuseppina Martella
- Department of Neuroscience, University of Rome Tor Vergata and Fondazione Santa Lucia, 00133 Rome, Italy; and
| | - Paola Bonsi
- Department of Neuroscience, University of Rome Tor Vergata and Fondazione Santa Lucia, 00133 Rome, Italy; and
| | - Chen Zhang
- *Center for Neurologic Diseases, Brigham and Women's Hospital, Program in Neuroscience, Harvard Medical School, Boston, MA 02115
| | - Emmanuel N. Pothos
- Department of Pharmacology and Experimental Therapeutics and Program in Neuroscience, Tufts University School of Medicine, Boston, MA 02111
| | - Jie Shen
- *Center for Neurologic Diseases, Brigham and Women's Hospital, Program in Neuroscience, Harvard Medical School, Boston, MA 02115
- To whom correspondence should be addressed at:
Center for Neurologic Diseases, Brigham and Women's Hospital, Program in Neuroscience, Harvard Medical School, New Research Building, Room 636E, 77 Avenue Louis Pasteur, Boston, MA 02115.E-mail:
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41
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Abstract
PR-Set7 is a histone methyltransferase that specifically monomethylates histone H4 lysine 20 (K20) and is essential for cell proliferation. Our results show that in PR-Set7 mutants, the DNA damage checkpoint is activated. This phenotype is manifested by reduction in both the mitotic and the S phase indexes, a delay in the progression through early mitosis, and strong reduction of cyclin B. Furthermore, in a double mutant of PR-Set7 and mei-41 (the fly ATR orthologue), the abnormalities of mitotic progression and the cyclin B protein level were rescued. PR-Set7 also showed a defect in chromosome condensation that was enhanced in the double mutant. We therefore propose that monomethylated H4K20 is involved in the maintenance of proper higher order structure of DNA and is consequently essential for chromosome condensation.
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Affiliation(s)
- Ayako Sakaguchi
- Waksman Institute, Department of Molecular Biology and Biochemistry, Cancer Institute of New Jersey, Rutgers University, Piscataway, NJ 08854, USA
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42
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Gjoerup OV, Wu J, Chandler-Militello D, Williams GL, Zhao J, Schaffhausen B, Jat PS, Roberts TM. Surveillance mechanism linking Bub1 loss to the p53 pathway. Proc Natl Acad Sci U S A 2007; 104:8334-9. [PMID: 17488820 PMCID: PMC1895950 DOI: 10.1073/pnas.0703164104] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Bub1 is a kinase believed to function primarily in the mitotic spindle checkpoint. Mutation or aberrant Bub1 expression is associated with chromosomal instability, aneuploidy, and human cancer. We now find that targeting Bub1 by RNAi or simian virus 40 (SV40) large T antigen in normal human diploid fibroblasts results in premature senescence. Interestingly, cells undergoing replicative senescence were also low in Bub1 expression, although ectopic Bub1 expression in presenescent cells was insufficient to extend lifespan. Premature senescence caused by lower Bub1 levels depends on p53. Senescence induction was blocked by dominant negative p53 expression or depletion of p21(CIP1), a p53 target. Importantly, cells with lower Bub1 levels and inactivated p53 became highly aneuploid. Taken together, our data highlight a role for p53 in monitoring Bub1 function, which may be part of a more general spindle checkpoint surveillance mechanism. Our data support the hypothesis that Bub1 compromise triggers p53-dependent senescence, which limits the production of aneuploid and potentially cancerous cells.
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Affiliation(s)
- Ole V. Gjoerup
- *Molecular Virology Program, University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213
- To whom correspondence may be addressed. E-mail: or
| | - Jiaping Wu
- Department of Cancer Biology, Dana–Farber Cancer Institute and Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115
| | - Devin Chandler-Militello
- Department of Cancer Biology, Dana–Farber Cancer Institute and Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115
| | - Grace L. Williams
- Department of Cancer Biology, Dana–Farber Cancer Institute and Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115
| | - Jean Zhao
- Department of Cancer Biology, Dana–Farber Cancer Institute and Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115
| | - Brian Schaffhausen
- Department of Biochemistry, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111
| | - Parmjit S. Jat
- Department of Neurodegenerative Disease, Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, United Kingdom
| | - Thomas M. Roberts
- Department of Cancer Biology, Dana–Farber Cancer Institute and Harvard Medical School, 1 Jimmy Fund Way, Boston, MA 02115
- To whom correspondence may be addressed. E-mail: or
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43
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Lee JH, Koh H, Kim M, Kim Y, Lee SY, Karess RE, Lee SH, Shong M, Kim JM, Kim J, Chung J. Energy-dependent regulation of cell structure by AMP-activated protein kinase. Nature 2007; 447:1017-20. [PMID: 17486097 DOI: 10.1038/nature05828] [Citation(s) in RCA: 320] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 04/10/2007] [Indexed: 12/11/2022]
Abstract
AMP-activated protein kinase (AMPK, also known as SNF1A) has been primarily studied as a metabolic regulator that is activated in response to energy deprivation. Although there is relatively ample information on the biochemical characteristics of AMPK, not enough data exist on the in vivo function of the kinase. Here, using the Drosophila model system, we generated the first animal model with no AMPK activity and discovered physiological functions of the kinase. Surprisingly, AMPK-null mutants were lethal with severe abnormalities in cell polarity and mitosis, similar to those of lkb1-null mutants. Constitutive activation of AMPK restored many of the phenotypes of lkb1-null mutants, suggesting that AMPK mediates the polarity- and mitosis-controlling functions of the LKB1 serine/threonine kinase. Interestingly, the regulatory site of non-muscle myosin regulatory light chain (MRLC; also known as MLC2) was directly phosphorylated by AMPK. Moreover, the phosphomimetic mutant of MRLC rescued the AMPK-null defects in cell polarity and mitosis, suggesting MRLC is a critical downstream target of AMPK. Furthermore, the activation of AMPK by energy deprivation was sufficient to cause dramatic changes in cell shape, inducing complete polarization and brush border formation in the human LS174T cell line, through the phosphorylation of MRLC. Taken together, our results demonstrate that AMPK has highly conserved roles across metazoan species not only in the control of metabolism, but also in the regulation of cellular structures.
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Affiliation(s)
- Jun Hee Lee
- National Creative Research Initiatives Center for Cell Growth Regulation, Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 373-1 Kusong-Dong, Yusong-Gu, Taejon 305-701, Korea
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44
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Abstract
Two cell cycle surveillance systems--the DNA damage checkpoint and the spindle checkpoint--guard against genomic instability. The protein kinase Chk1 is a well-established signal transducer in the DNA damage checkpoint. In this issue of Developmental Cell, Zachos et al.(2007) present evidence to indicate that Chk1 also plays a critical role in the spindle checkpoint, suggesting an interplay between the DNA damage and spindle checkpoints.
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Affiliation(s)
- Hongtao Yu
- Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390, USA.
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Zachos G, Black EJ, Walker M, Scott MT, Vagnarelli P, Earnshaw WC, Gillespie DA. Chk1 is required for spindle checkpoint function. Dev Cell 2007; 12:247-60. [PMID: 17276342 PMCID: PMC7115955 DOI: 10.1016/j.devcel.2007.01.003] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 12/01/2006] [Accepted: 01/10/2007] [Indexed: 11/28/2022]
Abstract
The spindle checkpoint delays anaphase onset in cells with mitotic spindle defects. Here, we show that Chk1, a component of the DNA damage and replication checkpoints, protects vertebrate cells against spontaneous chromosome missegregation and is required to sustain anaphase delay when spindle function is disrupted by taxol, but not when microtubules are completely depolymerized by nocodazole. Spindle checkpoint failure in Chk1-deficient cells correlates with decreased Aurora-B kinase activity and impaired phosphorylation and kinetochore localization of BubR1. Furthermore, Chk1 phosphorylates Aurora-B and enhances its catalytic activity in vitro. We propose that Chk1 augments spindle checkpoint signaling and is required for optimal regulation of Aurora-B and BubR1 when kinetochores produce a weakened signal. In addition, Chk1-deficient cells exhibit increased resistance to taxol. These results suggest a mechanism through which Chk1 could protect against tumorigenesis through its role in spindle checkpoint signaling.
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Affiliation(s)
- George Zachos
- Beatson Institute for Cancer Research, Garscube Estate, Switchback
Road, Glasgow G61 1BD, United Kingdom
- Correspondence:
(G.Z.), (D.A.F.G.)
| | - Elizabeth J. Black
- Beatson Institute for Cancer Research, Garscube Estate, Switchback
Road, Glasgow G61 1BD, United Kingdom
| | - Mark Walker
- Beatson Institute for Cancer Research, Garscube Estate, Switchback
Road, Glasgow G61 1BD, United Kingdom
| | - Mary T. Scott
- Beatson Institute for Cancer Research, Garscube Estate, Switchback
Road, Glasgow G61 1BD, United Kingdom
| | - Paola Vagnarelli
- Welcome Trust Centre for Cell Biology, University of Edinburgh,
Michael Swann Building, King’s Buildings,Mayfield Road, Edinburgh EH9 3JR,
United Kingdom
| | - William C. Earnshaw
- Welcome Trust Centre for Cell Biology, University of Edinburgh,
Michael Swann Building, King’s Buildings,Mayfield Road, Edinburgh EH9 3JR,
United Kingdom
| | - David A.F. Gillespie
- Beatson Institute for Cancer Research, Garscube Estate, Switchback
Road, Glasgow G61 1BD, United Kingdom
- Faculty of Biomedical and Life Sciences, University of Glasgow,
Glasgow G12 8QQ, United Kingdom
- Correspondence:
(G.Z.), (D.A.F.G.)
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46
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Abstract
BACKGROUND AND PURPOSE Aging is a major risk for stroke and a highly complex biological process believed to involve multiple mechanisms. Mutant mice that express low levels of the spindle assembly checkpoint protein BubR1 are known to develop several aging-associated phenotypes at a very young age, including cataracts, lordokyphosis, loss of subcutaneous fat, and impaired wound healing. However, whether BubR1 acts to prevent vascular aging has not yet been established. The present study was designed to investigate the vascular phenotype of mutant mice with low levels of BubR1. METHODS Morphological, functional, and biochemical analyses were performed on aortas and carotid arteries of 3- to 5-month-old BubR1 mutant mice and wild-type littermates. RESULTS Arterial wall thickness and inner diameter were significantly reduced in BubR1 mutant mice. Arterial walls of BubR1 mutant mice had low numbers of medial smooth muscle cells. Masson trichrome staining showed profound fibrosis in arterial walls of BubR1 mutant. In agreement with these morphological changes, functional analysis of pressurized isolated carotid arteries of BubR1 mutant mice demonstrated reduced elastic properties. Endothelium-dependent relaxations to acetylcholine and endothelium-independent relaxations to the nitric oxide donor DEA-NONOate were significantly reduced in carotid arteries of BubR1 mutant mice. Furthermore, enzymatic activity of nitric oxide synthase and levels of cyclic GMP were significantly reduced in aortas of mutant mice, but production of superoxide anions was significantly increased. CONCLUSIONS These findings demonstrate that BubR1 insufficiency in mice results in phenotypic changes reminiscent of vascular aging in humans and suggest a role for BubR1 in suppressing the vascular aging process.
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Affiliation(s)
- Takuya Matsumoto
- Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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47
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Abstract
The genetic study of titin has been notoriously difficult because of its size and complicated alternative splicing routes. Here, we have used zebrafish as an animal model to investigate the functions of individual titin isoforms. We identified 2 titin orthologs in zebrafish, ttna and ttnb, and annotated the full-length genomic sequences for both genes. We found that ttna, but not ttnb, is required for sarcomere assembly in the heart as well as the subsequent establishment of cardiac contractility. In fact, ttna is the earliest sarcomeric mRNA that is expressed in the heart, which makes it an early molecular marker for cardiomyocyte differentiation. Surprisingly, ttna is required for later steps of sarcomere assembly, including the assembly of Z-discs and A-bands, but not for early steps such as the assembly of Z-bodies and nonstriated myosin filaments. Reduction of individual titin isoforms in vivo using morpholino-modified antisense oligonucleotides indicated that (1) both N2B exon-containing and N2A exon-containing isoforms of ttna are required for sarcomere assembly in the heart; (2) N2A exon-containing isoforms of both ttna and ttnb are required for sarcomere assembly in the somites; and (3) the N2B exon-containing isoforms of ttnb are expressed later than other titin isoforms and are probably involved in modulating their expression; however, these isoforms of ttnb are not required for sarcomere assembly. Collectively, our results reveal distinct functions of different titin isoforms and suggest that various phenotypes in "titinopathies" may be attributable to the disruption of different titin isoforms.
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Affiliation(s)
- Michael Seeley
- Department of Biochemistry and Molecular Biology/Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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48
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Joshi M, Jeoung N, Obayashi M, Hattab E, Brocken E, Liechty E, Kubek M, Vattem K, Wek R, Harris R. Impaired growth and neurological abnormalities in branched-chain alpha-keto acid dehydrogenase kinase-deficient mice. Biochem J 2006; 400:153-62. [PMID: 16875466 PMCID: PMC1635446 DOI: 10.1042/bj20060869] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The BCKDH (branched-chain alpha-keto acid dehydrogenase complex) catalyses the rate-limiting step in the oxidation of BCAAs (branched-chain amino acids). Activity of the complex is regulated by a specific kinase, BDK (BCKDH kinase), which causes inactivation, and a phosphatase, BDP (BCKDH phosphatase), which causes activation. In the present study, the effect of the disruption of the BDK gene on growth and development of mice was investigated. BCKDH activity was much greater in most tissues of BDK-/- mice. This occurred in part because the E1 component of the complex cannot be phosphorylated due to the absence of BDK and also because greater than normal amounts of the E1 component were present in tissues of BDK-/- mice. Lack of control of BCKDH activity resulted in markedly lower blood and tissue levels of the BCAAs in BDK-/- mice. At 12 weeks of age, BDK-/- mice were 15% smaller than wild-type mice and their fur lacked normal lustre. Brain, muscle and adipose tissue weights were reduced, whereas weights of the liver and kidney were greater. Neurological abnormalities were apparent by hind limb flexion throughout life and epileptic seizures after 6-7 months of age. Inhibition of protein synthesis in the brain due to hyperphosphorylation of eIF2alpha (eukaryotic translation initiation factor 2alpha) might contribute to the neurological abnormalities seen in BDK-/- mice. BDK-/- mice show significant improvement in growth and appearance when fed a high protein diet, suggesting that higher amounts of dietary BCAA can partially compensate for increased oxidation in BDK-/- mice. Disruption of the BDK gene establishes that regulation of BCKDH by phosphorylation is critically important for the regulation of oxidative disposal of BCAAs. The phenotype of the BDK-/- mice demonstrates the importance of tight regulation of oxidative disposal of BCAAs for normal growth and neurological function.
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Affiliation(s)
- Mandar A. Joshi
- *Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Nam Ho Jeoung
- *Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Mariko Obayashi
- *Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Eyas M. Hattab
- †Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Eric G. Brocken
- †Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Edward A. Liechty
- ‡Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Michael J. Kubek
- §Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Krishna M. Vattem
- *Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Ronald C. Wek
- *Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
| | - Robert A. Harris
- *Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, U.S.A
- To whom correspondence should be addressed (email )
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49
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Abstract
BCAAs (branched-chain amino acids) are indispensable (essential) amino acids that are required for body protein synthesis. Indispensable amino acids cannot be synthesized by the body and must be acquired from the diet. The BCAA leucine provides hormone-like signals to tissues such as skeletal muscle, indicating overall nutrient sufficiency. BCAA metabolism provides an important transport system to move nitrogen throughout the body for the synthesis of dispensable (non-essential) amino acids, including the neurotransmitter glutamate in the central nervous system. BCAA metabolism is tightly regulated to maintain levels high enough to support these important functions, but at the same time excesses are prevented via stimulation of irreversible disposal pathways. It is well known from inborn errors of BCAA metabolism that dysregulation of the BCAA catabolic pathways that leads to excess BCAAs and their alpha-keto acid metabolites results in neural dysfunction. In this issue of Biochemical Journal, Joshi and colleagues have disrupted the murine BDK (branched-chain alpha-keto acid dehydrogenase kinase) gene. This enzyme serves as the brake on BCAA catabolism. The impaired growth and neurological abnormalities observed in this animal show conclusively the importance of tight regulation of indispensable amino acid metabolism.
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Affiliation(s)
- Susan M Hutson
- Department of Biochemistry and Molecular Biology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
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50
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Fusello AM, Mandik-Nayak L, Shih F, Lewis RE, Allen PM, Shaw AS. The MAPK Scaffold Kinase Suppressor of Ras Is Involved in ERK Activation by Stress and Proinflammatory Cytokines and Induction of Arthritis. J Immunol 2006; 177:6152-8. [PMID: 17056543 DOI: 10.4049/jimmunol.177.9.6152] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The MAPK ERK is required for LPS-induced TNF production by macrophages. Although the scaffold kinase suppressor of Ras (KSR)1 is required for efficient Erk activation by mitogenic stimuli, the role of KSR1 in ERK activation by inflammatory and stress stimuli is unknown. In this study, we examined the effects of KSR deficiency on ERK activation by stress stimuli and show that ERK activation by TNF, IL-1, and sorbitol is attenuated in the absence of KSR1. To determine the significance of this defect in vivo, we tested KSR-deficient mice using a passive transfer model of arthritis. We found that the induction of arthritis is impaired in the absence of KSR. Thus, KSR plays a role in ERK activation during inflammatory and stress responses both in vitro and in vivo.
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Affiliation(s)
- Angela M Fusello
- Department of Pathology and Department of Immunology, Washington University School of Medicine, 660 South Euclid, St. Louis, MO 63110, USA
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