101
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Lu G, Sun H, She P, Youn JY, Warburton S, Ping P, Vondriska TM, Cai H, Lynch CJ, Wang Y. Protein phosphatase 2Cm is a critical regulator of branched-chain amino acid catabolism in mice and cultured cells. J Clin Invest 2009; 119:1678-87. [PMID: 19411760 DOI: 10.1172/jci38151] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 02/25/2009] [Indexed: 01/26/2023] Open
Abstract
The branched-chain amino acids (BCAA) are essential amino acids required for protein homeostasis, energy balance, and nutrient signaling. In individuals with deficiencies in BCAA, these amino acids can be preserved through inhibition of the branched-chain-alpha-ketoacid dehydrogenase (BCKD) complex, the rate-limiting step in their metabolism. BCKD is inhibited by phosphorylation of its E1alpha subunit at Ser293, which is catalyzed by BCKD kinase. During BCAA excess, phosphorylated Ser293 (pSer293) becomes dephosphorylated through the concerted inhibition of BCKD kinase and the activity of an unknown intramitochondrial phosphatase. Using unbiased, proteomic approaches, we have found that a mitochondrial-targeted phosphatase, PP2Cm, specifically binds the BCKD complex and induces dephosphorylation of Ser293 in the presence of BCKD substrates. Loss of PP2Cm completely abolished substrate-induced E1alpha dephosphorylation both in vitro and in vivo. PP2Cm-deficient mice exhibited BCAA catabolic defects and a metabolic phenotype similar to the intermittent or intermediate types of human maple syrup urine disease (MSUD), a hereditary disorder caused by defects in BCKD activity. These results indicate that PP2Cm is the endogenous BCKD phosphatase required for nutrient-mediated regulation of BCKD activity and suggest that defects in PP2Cm may be responsible for a subset of human MSUD.
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Affiliation(s)
- Gang Lu
- Division of Molecular Medicine, Department of Anesthesiology, David Geffen School of Medicine, UCLA, Los Angeles, California 90095, USA
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102
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Lu G, Sun H, Korge P, Koehler CM, Weiss JN, Wang Y. Functional characterization of a mitochondrial Ser/Thr protein phosphatase in cell death regulation. Methods Enzymol 2009; 457:255-73. [PMID: 19426872 DOI: 10.1016/s0076-6879(09)05014-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Protein phosphorylation is a major form of posttranslational modification critical to cell signaling that also occurs in mitochondrial proteome. Yet, only very limited studies have been performed to characterize mitochondrial-targeted protein kinases or phosphatases. Recently, we identified a novel member of PP2C family (PP2Cm) that is a resident mitochondrial protein phosphatase which plays an important role in normal development and cell survival. In this chapter, we will describe the methods applied in the identification of PP2Cm as a resident mitochondrial protein phosphatase based on sequence analysis and biochemical characterization. We will also provide experimental protocols used to establish the intracellular localization of PP2Cm, to achieve loss and gain function of PP2Cm in cultured cells and intact tissue, and to assess the impact of PP2Cm deficiency on cell death, mitochondria oxidative phosphorylation and permeability transition pore opening.
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Affiliation(s)
- Gang Lu
- Department of Anesthesiology, Division of Molecular Medicine, UCLA, Los Angeles, California, USA
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103
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De Marchi U, Szabò I, Cereghetti GM, Hoxha P, Craigen WJ, Zoratti M. A maxi-chloride channel in the inner membrane of mammalian mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:1438-48. [DOI: 10.1016/j.bbabio.2008.08.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 08/01/2008] [Accepted: 08/12/2008] [Indexed: 01/09/2023]
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104
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Nguyen CT, Lu Q, Wang Y, Chen JN. Zebrafish as a model for cardiovascular development and disease. ACTA ACUST UNITED AC 2008; 5:135-140. [PMID: 22275951 DOI: 10.1016/j.ddmod.2009.02.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Catherine T Nguyen
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA
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105
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Monick MM, Powers LS, Barrett CW, Hinde S, Ashare A, Groskreutz DJ, Nyunoya T, Coleman M, Spitz DR, Hunninghake GW. Constitutive ERK MAPK activity regulates macrophage ATP production and mitochondrial integrity. THE JOURNAL OF IMMUNOLOGY 2008; 180:7485-96. [PMID: 18490749 DOI: 10.4049/jimmunol.180.11.7485] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A unique feature of human alveolar macrophages is their prolonged survival in the face of a stressful environment. We have shown previously that the ERK MAPK is constitutively active in these cells and is important in prolonging cell survival. This study examines the role of the ERK pathway in maintaining mitochondrial energy production. The data demonstrate that ATP levels in alveolar macrophages depend on intact mitochondria and optimal functioning of the electron transport chain. Significant levels of MEK and ERK localize to the mitochondria and inhibition of ERK activity induces an early and profound depletion in cellular ATP coincident with a loss of mitochondrial transmembrane potential. The effect of ERK suppression on ATP levels was specific, since it did not occur with PI3K/Akt, p38, or JNK suppression. ERK inhibition led to cytosolic release of mitochondrial proteins and caspase activation. Both ERK inhibition and mitochondrial blockers induced loss of plasma membrane permeability and cell death. The cell death induced by ERK inhibition had hallmarks of both apoptotic (caspase activation) and necrotic (ATP loss) cell death. By blocking ERK inhibition-induced reactive oxygen species, caspase activation was prevented, although necrotic pathways continued to induce cell death. This suggests that mitochondrial dysfunction caused by ERK inhibition generates both apoptotic and necrotic cell death-inducing pathways. As a composite, these data demonstrate a novel mitochondrial role for ERK in maintaining mitochondrial membrane potential and ATP production in human alveolar macrophages.
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Affiliation(s)
- Martha M Monick
- Department of Medicine, University of Iowa Carver College of Medicine and Veterans Administration Medical Center, Iowa City, IA 52242, USA.
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106
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Awano K, Amano K, Nagaura Y, Kanno SI, Echigo S, Tamura S, Kobayashi T. Phosphorylation of Protein Phosphatase 2Cζ by c-Jun NH2-Terminal Kinase at Ser92 Attenuates Its Phosphatase Activity. Biochemistry 2008; 47:7248-55. [DOI: 10.1021/bi800067p] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kenjiro Awano
- Department of Biochemistry and Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan, and Division of Oral Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Kazutaka Amano
- Department of Biochemistry and Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan, and Division of Oral Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Yuko Nagaura
- Department of Biochemistry and Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan, and Division of Oral Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Shin-ichiro Kanno
- Department of Biochemistry and Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan, and Division of Oral Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Seishi Echigo
- Department of Biochemistry and Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan, and Division of Oral Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Shinri Tamura
- Department of Biochemistry and Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan, and Division of Oral Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Takayasu Kobayashi
- Department of Biochemistry and Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan, and Division of Oral Surgery, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
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107
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MacLellan WR, Wang Y, Vondriska TM, Weiss JN, Ping P. Proteomic insights into cardiac cell death and survival. Proteomics Clin Appl 2008; 2:837-44. [PMID: 21136883 PMCID: PMC3808833 DOI: 10.1002/prca.200780121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Indexed: 11/06/2022]
Abstract
Cardiovascular disease is the leading cause of death and disability in the developed world. To design novel therapeutic strategies to treat and prevent this disease, better understanding of cardiac cell function is necessary. In addition to (and, indeed, in combination with) genetics, physiology and molecular biology, proteomics plays a critical role in our understanding of cardiovascular systems at multiple scales. The purpose of this review is to examine recent developments in the field of myocardial injury and protection, examining how proteomics has informed investigations into organelles, signaling complexes, and cardiac phenotype.
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Affiliation(s)
- W. Robb MacLellan
- Department of Medicine/Cardiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
- Department of Physiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
| | - Yibin Wang
- Department of Medicine/Cardiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
- Department of Physiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
- Department of Anesthesiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
| | - Thomas M. Vondriska
- Department of Medicine/Cardiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
- Department of Physiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
- Department of Anesthesiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
| | - James N. Weiss
- Department of Medicine/Cardiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
- Department of Physiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
| | - Peipei Ping
- Department of Medicine/Cardiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
- Department of Physiology, Cardiovascular Research Laboratories, University of California, Los Angeles, CA, USA
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108
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Lu G, Wang Y. FUNCTIONAL DIVERSITY OF MAMMALIAN TYPE 2C PROTEIN PHOSPHATASE ISOFORMS: NEW TALES FROM AN OLD FAMILY. Clin Exp Pharmacol Physiol 2008; 35:107-12. [DOI: 10.1111/j.1440-1681.2007.04843.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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109
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Saito S, Matsui H, Kawano M, Kumagai K, Tomishige N, Hanada K, Echigo S, Tamura S, Kobayashi T. Protein phosphatase 2Cepsilon is an endoplasmic reticulum integral membrane protein that dephosphorylates the ceramide transport protein CERT to enhance its association with organelle membranes. J Biol Chem 2007; 283:6584-93. [PMID: 18165232 DOI: 10.1074/jbc.m707691200] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein phosphatase 2Cepsilon (PP2Cepsilon), a mammalian PP2C family member, is expressed in various tissues and is implicated in the negative regulation of stress-activated protein kinase pathways. We show that PP2Cepsilon is an endoplasmic reticulum (ER) transmembrane protein with a transmembrane domain at the amino terminus and the catalytic domain facing the cytoplasm. Yeast two-hybrid screening of a human brain library using PP2Cepsilon as bait resulted in the isolation of a cDNA that encoded vesicle-associated membrane protein-associated protein A (VAPA). VAPA is an ER resident integral membrane protein involved in recruiting lipid-binding proteins such as the ceramide transport protein CERT to the ER membrane. Expression of PP2Cepsilon resulted in dephosphorylation of CERT in a VAPA expression-dependent manner, which was accompanied by redistribution of CERT from the cytoplasm to the Golgi apparatus. The expression of PP2Cepsilon also enhanced the association between CERT and VAPA. In addition, knockdown of PP2Cepsilon expression by short interference RNA attenuated the interaction between CERT and VAPA and the sphingomyelin synthesis. These results suggest that CERT is a physiological substrate of PP2Cepsilon and that dephosphorylation of CERT by PP2Cepsilon may play an important role in the regulation of ceramide trafficking from the ER to the Golgi apparatus.
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Affiliation(s)
- Satoko Saito
- Department of Biochemistry, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
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110
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Ong PL, Weng BC, Lu FJ, Lin ML, Chang TT, Hung RP, Chen CH. The anticancer effect of protein-extract from Bidens alba in human colorectal carcinoma SW480 cells via the reactive oxidative species- and glutathione depletion-dependent apoptosis. Food Chem Toxicol 2007; 46:1535-47. [PMID: 18226850 DOI: 10.1016/j.fct.2007.12.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 11/30/2007] [Accepted: 12/09/2007] [Indexed: 10/22/2022]
Abstract
Bidens alba has been used for healing cuts, injuries, swellings, hypertension, jaundice, and diabetes in some countries. However, the effect of B. alba on human cancer remains poorly understood. The goal of this study was to investigate whether B. alba protein-extract could have an anticancer property against human colorectal cancer. The human colorectal cancer SW 480 cells treated with the protein-extract of B. alba would cause marked DNA damages and apoptosis-related cellular morphologies. Treatment with 225 microg/ml B. alba protein-extract also led to the SW480 cells to produce readily intracellular reactive oxygen species (ROS) after 1h of treatment and last to 24 h. The intracellular glutathione (GSH) depletion occurred after 12-24h of treatment. The treatment of the protein-extract would also caused mitochondrial transmembrane potential (DeltaPsi(m)) to decrease and cytosolic cytochrome c to increase. The caspase 3/7 activities were activated from 3 to 6 h after the treatment. The percentages of apoptosis induced by the protein-extract of B. alba decreased 26.4%, 10.1%, and 29.4% when the SW 480 cells were pretreated with Vitamin C, N-acetylcysteine, and Boc-Asp(OMe)-fmk, respectively. Taken together, we demonstrated for the first time that the protein-extract of B. alba could induce apoptosis that was related to the ROS production and GSH depletion in human colorectal cancer. The protein-extract of B. alba might have therapeutic value against the human colorectal cancer.
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Affiliation(s)
- Ping-Lin Ong
- Department of Biochemical Science and Technology, College of Life Sciences, National Chiayi University, Chiayi, Taiwan
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111
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Baden KN, Murray J, Capaldi RA, Guillemin K. Early Developmental Pathology Due to Cytochrome c Oxidase Deficiency Is Revealed by a New Zebrafish Model. J Biol Chem 2007; 282:34839-49. [PMID: 17761683 DOI: 10.1074/jbc.m703528200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Deficiency of cytochrome c oxidase (COX) is associated with significant pathology in humans. However, the consequences for organogenesis and early development are not well understood. We have investigated these issues using a zebrafish model. COX deficiency was induced using morpholinos to reduce expression of CoxVa, a structural subunit, and Surf1, an assembly factor, both of which impaired COX assembly. Reduction of COX activity to 50% resulted in developmental defects in endodermal tissue, cardiac function, and swimming behavior. Cellular investigations revealed different underlying mechanisms. Apoptosis was dramatically increased in the hindbrain and neural tube, and secondary motor neurons were absent or abnormal, explaining the motility defect. In contrast, the heart lacked apoptotic cells but showed increasingly poor performance over time, consistent with energy deficiency. The zebrafish model has revealed tissue-specific responses to COX deficiency and holds promise for discovery of new therapies to treat mitochondrial diseases in humans.
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Affiliation(s)
- Katrina N Baden
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1229, USA
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