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Xu H, Liu T, Dai Y, Li N, Cao Z. The role of ERK1/2 signaling in diabetes: pathogenic and therapeutic implications. Front Pharmacol 2025; 16:1600251. [PMID: 40417223 PMCID: PMC12098375 DOI: 10.3389/fphar.2025.1600251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2025] [Accepted: 04/28/2025] [Indexed: 05/27/2025] Open
Abstract
ERK1/2 (extracellular signal-regulated kinase 1/2) is an important member of the MAPK (mitogen-activated protein kinase) family and is widely involved in many biological processes such as cell proliferation, differentiation, apoptosis and migration. After activation by phosphorylation, ERK1/2 can be transferred into the nucleus and directly or indirectly affect the activity of transcription factors, thereby regulating gene expression. More and more studies have shown that ERK1/2 plays an important role in diabetes and its complications, such as insulin secretion, islet β cell function, diabetic cardiomyopathy, diabetic nephropathy, renal fibrosis, lipogenesis, diabetic vasculopathy, etc. These effects reveal the complexity and diversity of the ERK1/2 signaling pathway in the pathogenesis of diabetes, and its activation and inhibition mechanisms in multiple physiological and pathological processes provide potential targets for diabetes treatment. The purpose of this mini-review is to explore the key role of ERK1/2 in diabetes and the progress of research on targeted inhibitors of ERK1/2, which provides new strategies for the treatment of diabetes.
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Affiliation(s)
- Hanlin Xu
- Department of Thoracic Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Tao Liu
- Department of Pharmacy, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yanfen Dai
- Department of Hyperbaric Oxygen, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Na Li
- Department of Pharmacy, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Zhanqi Cao
- Department of Pharmacy, The Affiliated Hospital of Qingdao University, Qingdao, China
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2
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Sun L, Cui ZG, Feng Q, Muhammad JS, Jin YJ, Zhao S, Zhou L, Wu CAI. Fenvalerate exposure induces AKT/AMPK-dependent alterations in glucose metabolism in hepatoma cells. Front Pharmacol 2025; 16:1540567. [PMID: 40070568 PMCID: PMC11893604 DOI: 10.3389/fphar.2025.1540567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2024] [Accepted: 01/27/2025] [Indexed: 03/14/2025] Open
Abstract
Background Fenvalerate (Fen) is a synthetic pyrethroid insecticide significantly associated with an increased risk of type 2 diabetes. Tumor cells exhibit a shift in glucose metabolism, known as the Warburg effect. Accordingly, we aimed to elucidate whether Fen interferes with insulin signaling and affects hepatoma cell metabolism. Methods The cells were subjected to Fen to assess glucose uptake, acidification, oxygen consumption, and ATP production. ROS generation, mitochondrial membrane potentials, and protein expression were evaluated by flow cytometry, immunofluorescence microscopy, and western blot analyses. Results Our results demonstrated that Fen promotes glucose uptake, lactate production, and ATP generation in various cancer cells. Moreover, Fen enhanced insulin receptor phosphorylation and upregulated p-AKT/p-AMPK expression. Fen enhanced insulin receptor sensitivity and endocytosis via reactive oxygen species generation rather than the PP2B pathway. Additionally, the antioxidants N-acetyl-L-cysteine and ascorbic acid reversed the Fen-induced increase in glycolysis. Finally, chronic Fen exposure protected hepatoma cells against metformin-induced cell death via the AKT/AMPK pathway. Conclusion These findings raise concerns regarding the safety of Fen and its potential role in altering cancer cell metabolism, affecting insulin signaling and treating drug resistance, thereby necessitating further research.
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Affiliation(s)
- Lu Sun
- Department of Pediatric Cardiology, Heart Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Zheng-Guo Cui
- Department of Environmental Health, University of Fukui School of Medical Sciences, Fukui, Japan
| | - Qianwen Feng
- Biocytogen Phaceuticals, Daxing Bio-Medicine Industry Park, Beijing, China
| | - Jibran Sualeh Muhammad
- Department of Biomedical Sciences, College of Medicine and Health, University of Birmingham, Birmingham, United Kingdom
| | - Yu-Jie Jin
- Department of General Practice, The First Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Songji Zhao
- Advanced Clinical Research Center, Fukushima Global Medical Science Center, Fukushima Medical University, Fukushima, Japan
| | - Lingqi Zhou
- Department of Pediatric Cardiology, Heart Center, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Cheng-AI Wu
- Department of Molecular Orthopedics, Beijing Research Institute of Traumatology and Orthopedics, Beijing Jishuitan Hospital, Beijing, China
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3
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Sekar JAP, Li YC, Schlessinger A, Pandey G. A web portal for exploring kinase-substrate interactions. NPJ Syst Biol Appl 2024; 10:113. [PMID: 39362876 PMCID: PMC11450209 DOI: 10.1038/s41540-024-00442-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 09/21/2024] [Indexed: 10/05/2024] Open
Abstract
Interactions between protein kinases and their substrates are critical for the modulation of complex signaling pathways. Currently, there is a large amount of information available about kinases and their substrates in disparate public databases. However, these data are difficult to interpret in the context of cellular systems, which can be facilitated by examining interactions among multiple proteins at once, such as the network of interactions that constitute a signaling pathway. We present KiNet, a user-friendly web portal that integrates and shares information about kinase-substrate interactions from multiple databases of post-translational modifications. KiNet enables the visual exploration of these interactions in systems contexts, such as pathways, domain families, and custom protein set inputs, in an interactive fashion. We expect KiNet to be useful as a knowledge discovery tool for kinase-substrate interactions, and the aggregated KiNet dataset to be useful for protein kinase studies and systems-level analyses. The portal is available at https://kinet.kinametrix.com/ .
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Affiliation(s)
- John A P Sekar
- Department of Genetics and Genomic Sciences, Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Yan Chak Li
- Department of Genetics and Genomic Sciences, Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
| | - Gaurav Pandey
- Department of Genetics and Genomic Sciences, Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
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4
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Christen D, Lauinger M, Brunner M, Dengjel J, Brummer T. The mTOR pathway controls phosphorylation of BRAF at T401. Cell Commun Signal 2024; 22:428. [PMID: 39223665 PMCID: PMC11370054 DOI: 10.1186/s12964-024-01808-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2024] [Accepted: 08/24/2024] [Indexed: 09/04/2024] Open
Abstract
BRAF serves as a gatekeeper of the RAS/RAF/MEK/ERK pathway, which plays a crucial role in homeostasis. Since aberrant signalling of this axis contributes to cancer and other diseases, it is tightly regulated by crosstalk with the PI3K/AKT/mTOR pathway and ERK mediated feedback loops. For example, ERK limits BRAF signalling through phosphorylation of multiple residues. One of these, T401, is widely considered as an ERK substrate following acute pathway activation by growth factors. Here, we demonstrate that prominent T401 phosphorylation (pT401) of endogenous BRAF is already observed in the absence of acute stimulation in various cell lines of murine and human origin. Importantly, the BRAF/RAF1 inhibitor naporafenib, the MEK inhibitor trametinib and the ERK inhibitor ulixertinib failed to reduce pT401 levels in these settings, supporting an alternative ERK-independent pathway to T401 phosphorylation. In contrast, the mTOR inhibitor torin1 and the dual-specific PI3K/mTOR inhibitor dactolisib significantly suppressed pT401 levels in all investigated cell types, in both a time and concentration dependent manner. Conversely, genetic mTOR pathway activation by oncogenic RHEB (Q64L) and mTOR (S2215Y and R2505P) mutants substantially increased pT401, an effect that was reverted by dactolisib and torin1 but not by trametinib. We also show that shRNAmir mediated depletion of the mTORC1 complex subunit Raptor significantly enhanced the suppression of T401 phosphorylation by a low torin1 dose, while knockdown of the mTORC2 complex subunit Rictor was less effective. Using mass spectrometry, we provide further evidence that torin1 suppresses the phosphorylation of T401, S405 and S409 but not of other important regulatory phosphorylation sites such as S446, S729 and S750. In summary, our data identify the mTOR axis and its inhibitors of (pre)clinical relevance as novel modulators of BRAF phosphorylation at T401.
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Affiliation(s)
- Daniel Christen
- Institute of Molecular Medicine, University of Freiburg, Stefan-Meier-Str. 17, 79104, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
- German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), Partner Site Freiburg and, Heidelberg, 69120, Germany
| | - Manuel Lauinger
- Institute of Molecular Medicine, University of Freiburg, Stefan-Meier-Str. 17, 79104, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Melanie Brunner
- Department of Biology, University of Fribourg, Chemin du Museé 10, 1700, Fribourg, Switzerland
| | - Jörn Dengjel
- Department of Biology, University of Fribourg, Chemin du Museé 10, 1700, Fribourg, Switzerland
| | - Tilman Brummer
- Institute of Molecular Medicine, University of Freiburg, Stefan-Meier-Str. 17, 79104, Freiburg, Germany.
- German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), Partner Site Freiburg and, Heidelberg, 69120, Germany.
- Comprehensive Cancer Center Freiburg (CCCF), Medical Center, Faculty of Medicine, University of Freiburg, University of Freiburg, 79106, Freiburg, Germany.
- Center for Biological Signalling Studies BIOSS, University of Freiburg, 79104, Freiburg, Germany.
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5
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Martin-Vega A, Cobb MH. Navigating the ERK1/2 MAPK Cascade. Biomolecules 2023; 13:1555. [PMID: 37892237 PMCID: PMC10605237 DOI: 10.3390/biom13101555] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 10/16/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023] Open
Abstract
The RAS-ERK pathway is a fundamental signaling cascade crucial for many biological processes including proliferation, cell cycle control, growth, and survival; common across all cell types. Notably, ERK1/2 are implicated in specific processes in a context-dependent manner as in stem cells and pancreatic β-cells. Alterations in the different components of this cascade result in dysregulation of the effector kinases ERK1/2 which communicate with hundreds of substrates. Aberrant activation of the pathway contributes to a range of disorders, including cancer. This review provides an overview of the structure, activation, regulation, and mutational frequency of the different tiers of the cascade; with a particular focus on ERK1/2. We highlight the importance of scaffold proteins that contribute to kinase localization and coordinate interaction dynamics of the kinases with substrates, activators, and inhibitors. Additionally, we explore innovative therapeutic approaches emphasizing promising avenues in this field.
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Affiliation(s)
- Ana Martin-Vega
- Department of Pharmacology, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390, USA;
| | - Melanie H. Cobb
- Department of Pharmacology, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390, USA;
- Simmons Comprehensive Cancer Center, UT Southwestern Medical Center, 6001 Forest Park Rd., Dallas, TX 75390, USA
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Cao R, Tian H, Zhang Y, Liu G, Xu H, Rao G, Tian Y, Fu X. Signaling pathways and intervention for therapy of type 2 diabetes mellitus. MedComm (Beijing) 2023; 4:e283. [PMID: 37303813 PMCID: PMC10248034 DOI: 10.1002/mco2.283] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 04/18/2023] [Accepted: 04/27/2023] [Indexed: 06/13/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) represents one of the fastest growing epidemic metabolic disorders worldwide and is a strong contributor for a broad range of comorbidities, including vascular, visual, neurological, kidney, and liver diseases. Moreover, recent data suggest a mutual interplay between T2DM and Corona Virus Disease 2019 (COVID-19). T2DM is characterized by insulin resistance (IR) and pancreatic β cell dysfunction. Pioneering discoveries throughout the past few decades have established notable links between signaling pathways and T2DM pathogenesis and therapy. Importantly, a number of signaling pathways substantially control the advancement of core pathological changes in T2DM, including IR and β cell dysfunction, as well as additional pathogenic disturbances. Accordingly, an improved understanding of these signaling pathways sheds light on tractable targets and strategies for developing and repurposing critical therapies to treat T2DM and its complications. In this review, we provide a brief overview of the history of T2DM and signaling pathways, and offer a systematic update on the role and mechanism of key signaling pathways underlying the onset, development, and progression of T2DM. In this content, we also summarize current therapeutic drugs/agents associated with signaling pathways for the treatment of T2DM and its complications, and discuss some implications and directions to the future of this field.
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Affiliation(s)
- Rong Cao
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
| | - Huimin Tian
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China Medical School, West China HospitalSichuan UniversityChengduSichuanChina
| | - Yu Zhang
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China Medical School, West China HospitalSichuan UniversityChengduSichuanChina
| | - Geng Liu
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
| | - Haixia Xu
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
| | - Guocheng Rao
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China Medical School, West China HospitalSichuan UniversityChengduSichuanChina
| | - Yan Tian
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
| | - Xianghui Fu
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China HospitalSichuan University and Collaborative Innovation Center of BiotherapyChengduSichuanChina
- Department of Endocrinology and MetabolismState Key Laboratory of Biotherapy and Cancer CenterWest China Medical School, West China HospitalSichuan UniversityChengduSichuanChina
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7
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Cleveland KH, Schnellmann RG. The β 2-adrenergic receptor agonist formoterol restores mitochondrial homeostasis in glucose-induced renal proximal tubule injury through separate integrated pathways. Biochem Pharmacol 2023; 209:115436. [PMID: 36720358 DOI: 10.1016/j.bcp.2023.115436] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/19/2023] [Accepted: 01/23/2023] [Indexed: 01/31/2023]
Abstract
Mitochondrial dysfunction drives the development and progression of diabetic kidney disease (DKD). Previously, we discovered that the β2-adrenergic receptor (AR) agonist formoterol regulates mitochondrial dynamics in the hyperglycemic renal proximal tubule. The goal of this study was to identify signaling mechanisms through which formoterol restores the mitochondrial fission/fusion proteins Drp1 and Mfn1. Using primary renal proximal tubule cells (RPTC), the effect of chronic high glucose on RhoA/ROCK1/Drp1 and Raf/MEK1/2/ERK1/2/Mfn1 signaling was determined. In glucose-treated RPTC, RhoA became hyperactive, leading to ROCK1-induced activation of Drp1. Treatment with formoterol and/or pharmacological inhibitors targeting RhoA, ROCK1 and Drp1 blocked RhoA and Drp1 hyperactivity. Inhibiting this pathway also restored maximal mitochondrial respiration. By preventing Gβγ signaling with gallein, we determined that formoterol signals through the Gβγ subunit of the β2-AR to restore RhoA and Drp1. Furthermore, formoterol restored this pathway by blocking binding of RhoA with the guanine nucleotide exchange factor p114RhoGEF. Formoterol also restored the mitochondrial fusion protein Mfn1 through a second Gβγ-dependent mechanism composed of Raf/MEK1/2/ERK1/2/Mfn1. Glucose-treated RPTC exhibited decreased Mfn1 activity, which was restored with formoterol. Pharmacological inhibition of Gβγ, Raf and MEK1/2 also restored Mfn1 activity. We demonstrate that glucose promotes the interaction between RhoA and p114RhoGEF, leading to increased RhoA and ROCK1-mediated activation of Drp1, and decreases Mfn1 activity through Raf/MEK1/2/ERK1/2. Formoterol restores these pathways and mitochondrial function in response to elevated glucose by activating separate yet integrative pathways that promote mitochondrial biogenesis, decreased fission and increased fusion in RPTC, further supporting its potential as a therapeutic for DKD.
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Affiliation(s)
- Kristan H Cleveland
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, United States
| | - Rick G Schnellmann
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, United States; Southern Arizona VA Health Care System, Tucson, AZ, United States; Southwest Environmental Health Science Center, University of Arizona, Tucson, AZ, United States.
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8
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Zhang J, Zhang L, Nie J, Lin Y, Li Y, Xu W, Zhao JY, Zhao SM, Wang C. Calcineurin inactivation inhibits pyruvate dehydrogenase complex activity and induces the Warburg effect. Oncogene 2021; 40:6692-6702. [PMID: 34667275 DOI: 10.1038/s41388-021-02065-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 09/24/2021] [Accepted: 10/05/2021] [Indexed: 12/25/2022]
Abstract
Calcineurin is a calcium- and calmodulin-dependent serine/threonine protein phosphatase that connects the Ca2+-dependent signalling to multiple cellular responses. Calcineurin inhibitors (CNIs) have been widely used to suppress immune response in allograft patients. However, CNIs significantly increase cancer incidence in transplant recipients compared with the general population. Accumulating evidence suggests that CNIs may promote the malignant transformation of cancer cells in addition to its role in immunosuppression, but the underlying mechanisms remain poorly understood. Here, we show that calcineurin interacts with pyruvate dehydrogenase complex (PDC), a mitochondrial gatekeeper enzyme that connects two key metabolic pathways of cells, glycolysis and the tricarboxylic acid cycle. Mitochondrial-localized calcineurin dephosphorylates PDHA1 at Ser232, Ser293 and Ser300, and thus enhances PDC enzymatic activity, remodels cellular glycolysis and oxidative phosphorylation, and suppresses cancer cell proliferation. Hypoxia attenuates mitochondrial translocation of calcineurin to promote PDC inactivation. Moreover, CNIs promote metabolic remodelling and the Warburg effect by blocking calcineurin-mediated PDC activation in cancer cells. Our findings indicate that calcineurin is a critical regulator of mitochondrial metabolism and suggest that CNIs may promote tumorigenesis through inhibition of the calcineurin-PDC pathway.
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Affiliation(s)
- Jianong Zhang
- Obstetrics & Gynecology Hospital of Fudan University, State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Key Laboratory of Reproduction Regulation of NPFPC (SIPPR, IRD), School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Liang Zhang
- Obstetrics & Gynecology Hospital of Fudan University, State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Key Laboratory of Reproduction Regulation of NPFPC (SIPPR, IRD), School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Ji Nie
- Obstetrics & Gynecology Hospital of Fudan University, State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Key Laboratory of Reproduction Regulation of NPFPC (SIPPR, IRD), School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Yan Lin
- Obstetrics & Gynecology Hospital of Fudan University, State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Key Laboratory of Reproduction Regulation of NPFPC (SIPPR, IRD), School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Yao Li
- Obstetrics & Gynecology Hospital of Fudan University, State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Key Laboratory of Reproduction Regulation of NPFPC (SIPPR, IRD), School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Wei Xu
- Shanghai Fifth People's Hospital and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Jian-Yuan Zhao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Shi-Min Zhao
- Obstetrics & Gynecology Hospital of Fudan University, State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Key Laboratory of Reproduction Regulation of NPFPC (SIPPR, IRD), School of Life Sciences, Fudan University, Shanghai, 200438, China.
| | - Chenji Wang
- Obstetrics & Gynecology Hospital of Fudan University, State Key Laboratory of Genetic Engineering, MOE Engineering Research Center of Gene Technology, Key Laboratory of Reproduction Regulation of NPFPC (SIPPR, IRD), School of Life Sciences, Fudan University, Shanghai, 200438, China.
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Thiel G, Schmidt T, Rössler OG. Ca 2+ Microdomains, Calcineurin and the Regulation of Gene Transcription. Cells 2021; 10:cells10040875. [PMID: 33921430 PMCID: PMC8068893 DOI: 10.3390/cells10040875] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/06/2021] [Accepted: 04/09/2021] [Indexed: 12/18/2022] Open
Abstract
Ca2+ ions function as second messengers regulating many intracellular events, including neurotransmitter release, exocytosis, muscle contraction, metabolism and gene transcription. Cells of a multicellular organism express a variety of cell-surface receptors and channels that trigger an increase of the intracellular Ca2+ concentration upon stimulation. The elevated Ca2+ concentration is not uniformly distributed within the cytoplasm but is organized in subcellular microdomains with high and low concentrations of Ca2+ at different locations in the cell. Ca2+ ions are stored and released by intracellular organelles that change the concentration and distribution of Ca2+ ions. A major function of the rise in intracellular Ca2+ is the change of the genetic expression pattern of the cell via the activation of Ca2+-responsive transcription factors. It has been proposed that Ca2+-responsive transcription factors are differently affected by a rise in cytoplasmic versus nuclear Ca2+. Moreover, it has been suggested that the mode of entry determines whether an influx of Ca2+ leads to the stimulation of gene transcription. A rise in cytoplasmic Ca2+ induces an intracellular signaling cascade, involving the activation of the Ca2+/calmodulin-dependent protein phosphatase calcineurin and various protein kinases (protein kinase C, extracellular signal-regulated protein kinase, Ca2+/calmodulin-dependent protein kinases). In this review article, we discuss the concept of gene regulation via elevated Ca2+ concentration in the cytoplasm and the nucleus, the role of Ca2+ entry and the role of enzymes as signal transducers. We give particular emphasis to the regulation of gene transcription by calcineurin, linking protein dephosphorylation with Ca2+ signaling and gene expression.
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10
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Roy J, Cyert MS. Identifying New Substrates and Functions for an Old Enzyme: Calcineurin. Cold Spring Harb Perspect Biol 2020; 12:a035436. [PMID: 31308145 PMCID: PMC7050593 DOI: 10.1101/cshperspect.a035436] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Biological processes are dynamically regulated by signaling networks composed of protein kinases and phosphatases. Calcineurin, or PP3, is a conserved phosphoserine/phosphothreonine-specific protein phosphatase and member of the PPP family of phosphatases. Calcineurin is unique, however, in its activation by Ca2+ and calmodulin. This ubiquitously expressed phosphatase controls Ca2+-dependent processes in all human tissues, but is best known for driving the adaptive immune response by dephosphorylating the nuclear factor of the activated T-cells (NFAT) family of transcription factors. Therefore, calcineurin inhibitors, FK506 (tacrolimus), and cyclosporin A serve as immunosuppressants. We describe some of the adverse effects associated with calcineurin inhibitors that result from inhibition of calcineurin in nonimmune tissues, illustrating the many functions of this enzyme that have yet to be elucidated. In fact, calcineurin has essential roles beyond the immune system, from yeast to humans, but since its discovery more than 30 years ago, only a small number of direct calcineurin substrates have been shown (∼75 proteins). This is because of limitations in current methods for identification of phosphatase substrates. Here we discuss recent insights into mechanisms of calcineurin activation and substrate recognition that have been critical in the development of novel approaches for identifying its targets systematically. Rather than comprehensively reviewing known functions of calcineurin, we highlight new approaches to substrate identification for this critical regulator that may reveal molecular mechanisms underlying toxicities caused by calcineurin inhibitor-based immunosuppression.
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Affiliation(s)
- Jagoree Roy
- Department of Biology, Stanford University, Stanford, California 94305-5020
| | - Martha S Cyert
- Department of Biology, Stanford University, Stanford, California 94305-5020
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11
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Fan L, Shan A, Su Y, Cheng Y, Ji H, Yang Q, Lei Y, Liu B, Wang W, Ning G, Cao Y, Jiang X. MiR-221/222 Inhibit Insulin Production of Pancreatic β-Cells in Mice. Endocrinology 2020; 161:5639771. [PMID: 31761936 DOI: 10.1210/endocr/bqz027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 11/23/2019] [Indexed: 11/19/2022]
Abstract
Microribonucleic acids (miRNAs) are essential for the regulation of development, proliferation, and functions of pancreatic β-cells. The conserved miR-221/222 cluster is an important regulator in multiple cellular processes. Here we investigated the functional role of miR-221/222 in the regulation of β-cell proliferation and functions in transgenic mouse models. We generated 2 pancreatic β-cell-specific-miR-221/222 transgenic mouse models on a C57BL/6J background. The glucose metabolic phenotypes, β-cell mass, and β-cell functions were analyzed in the mouse models. Adenovirus-mediated overexpression of miR-221/222 was performed on β-cells and mouse insulinoma 6 (MIN6) cells to explore the effect and mechanisms of miR-221/222 on β-cell proliferation and functions. Luciferase reporter assay, histological analysis, and quantitative polymerase chain reaction (PCR) were carried out to study the direct target genes of miR-221/222 in β-cells. The expression of miR-221/222 was significantly upregulated in β-cells from the high-fat diet (HFD)-fed mice and db/db mice. Overexpression of miR-221/222 impaired the insulin production and secretion of β-cells and resulted in glucose intolerance in vivo. The β-cell mass and proliferation were increased by miR-221/222 expression via Cdkn1b and Cdkn1c. MiR-221/222 repressed insulin transcription activity through targeting Nfatc3 and lead to reduction of insulin in β-cells. Our findings demonstrate that miR-221/222 are important regulators of β-cell proliferation and insulin production. The expression of miR-221/222 in β-cells could regulate glucose metabolism in physiological and pathological processes.
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Affiliation(s)
- Liwen Fan
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Aijing Shan
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Yutong Su
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Yulong Cheng
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - He Ji
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Qi Yang
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Ying Lei
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Bei Liu
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Weiqing Wang
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Guang Ning
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Yanan Cao
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Xiuli Jiang
- National Clinical Research Centre for Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory for Endocrine Tumors, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
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12
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Calcineurin controls gene transcription following stimulation of a Gαq-coupled designer receptor. Exp Cell Res 2019; 383:111553. [DOI: 10.1016/j.yexcr.2019.111553] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 08/07/2019] [Accepted: 08/10/2019] [Indexed: 01/07/2023]
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13
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Sabatini PV, Speckmann T, Lynn FC. Friend and foe: β-cell Ca 2+ signaling and the development of diabetes. Mol Metab 2019; 21:1-12. [PMID: 30630689 PMCID: PMC6407368 DOI: 10.1016/j.molmet.2018.12.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/03/2018] [Accepted: 12/19/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The divalent cation Calcium (Ca2+) regulates a wide range of processes in disparate cell types. Within insulin-producing β-cells, increases in cytosolic Ca2+ directly stimulate insulin vesicle exocytosis, but also initiate multiple signaling pathways. Mediated through activation of downstream kinases and transcription factors, Ca2+-regulated signaling pathways leverage substantial influence on a number of critical cellular processes within the β-cell. Additionally, there is evidence that prolonged activation of these same pathways is detrimental to β-cell health and may contribute to Type 2 Diabetes pathogenesis. SCOPE OF REVIEW This review aims to briefly highlight canonical Ca2+ signaling pathways in β-cells and how β-cells regulate the movement of Ca2+ across numerous organelles and microdomains. As a main focus, this review synthesizes experimental data from in vitro and in vivo models on both the beneficial and detrimental effects of Ca2+ signaling pathways for β-cell function and health. MAJOR CONCLUSIONS Acute increases in intracellular Ca2+ stimulate a number of signaling cascades, resulting in (de-)phosphorylation events and activation of downstream transcription factors. The short-term stimulation of these Ca2+ signaling pathways promotes numerous cellular processes critical to β-cell function, including increased viability, replication, and insulin production and secretion. Conversely, chronic stimulation of Ca2+ signaling pathways increases β-cell ER stress and results in the loss of β-cell differentiation status. Together, decades of study demonstrate that Ca2+ movement is tightly regulated within the β-cell, which is at least partially due to its dual roles as a potent signaling molecule.
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Affiliation(s)
- Paul V Sabatini
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada; Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Thilo Speckmann
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Francis C Lynn
- Diabetes Research Group, BC Children's Hospital Research Institute, Vancouver, British Columbia, Canada; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada; Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
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14
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Michael ES, Covic L, Kuliopulos A. Trace amine-associated receptor 1 (TAAR1) promotes anti-diabetic signaling in insulin-secreting cells. J Biol Chem 2019; 294:4401-4411. [PMID: 30670596 DOI: 10.1074/jbc.ra118.005464] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 01/16/2019] [Indexed: 12/25/2022] Open
Abstract
Pancreatic β-cell failure in type 2 diabetes mellitus is a serious challenge that results in an inability of the pancreas to produce sufficient insulin to properly regulate blood glucose levels. Trace amine-associated receptor 1 (TAAR1) is a G protein-coupled receptor expressed by β-cells that has recently been proposed as a potential target for improving glycemic control and suppressing binge eating behaviors. We discovered that TAAR1 is coupled to Gαs-signaling pathways in insulin-secreting β-cells to cause protein kinase A (PKA)/exchange protein activated by cAMP (Epac)-dependent release of insulin, activation of RAF proto-oncogene, Ser/Thr kinase (Raf)-mitogen-activated protein kinase (MAPK) signaling, induction of cAMP response element-binding protein (CREB)-insulin receptor substrate 2 (Irs-2), and increased β-cell proliferation. Interestingly, TAAR1 triggered cAMP-mediated calcium influx and release from internal stores, both of which were required for activation of a MAPK cascade utilizing calmodulin-dependent protein kinase II (CaMKII), Raf, and MAPK/ERK kinase 1/2 (MEK1/2). Together, these data identify TAAR1/Gαs-mediated signaling pathways that promote insulin secretion, improved β-cell function and proliferation, and highlight TAAR1 as a promising new target for improving β-cell health in type 2 diabetes mellitus.
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Affiliation(s)
- Emily S Michael
- From the Center for Hemostasis and Thrombosis Research, Tufts Medical Center, Department of Medicine, Tufts University School of Graduate Biomedical Sciences/Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Lidija Covic
- From the Center for Hemostasis and Thrombosis Research, Tufts Medical Center, Department of Medicine, Tufts University School of Graduate Biomedical Sciences/Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Athan Kuliopulos
- From the Center for Hemostasis and Thrombosis Research, Tufts Medical Center, Department of Medicine, Tufts University School of Graduate Biomedical Sciences/Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111
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15
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Langfermann DS, Rössler OG, Thiel G. Stimulation of B-Raf increases c-Jun and c-Fos expression and upregulates AP-1-regulated gene transcription in insulinoma cells. Mol Cell Endocrinol 2018; 472:126-139. [PMID: 29225069 DOI: 10.1016/j.mce.2017.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 12/05/2017] [Accepted: 12/07/2017] [Indexed: 01/15/2023]
Abstract
Stimulation of pancreatic β-cells with glucose activates the protein kinases B-Raf and extracellular signal-regulated protein kinase that participate in glucose sensing. Inhibition of both kinases results in impairment of glucose-regulated gene transcription. To analyze the signaling pathway controlled by B-Raf, we expressed a conditionally active form of B-Raf in INS-1 insulinoma cells. Here, we show that stimulation of B-Raf strongly activated the transcription factor AP-1 which is accompanied by increased c-Jun and c-Fos promoter activities, an upregulation of c-Jun and c-Fos biosynthesis, and elevated transcriptional activation potentials of c-Jun and c-Fos. Mutational analysis identified the AP-1 sites within the c-Jun promoter and the serum response element (SRE) within the c-Fos promoter as the essential genetic elements connecting B-Raf stimulation with AP-1 activation. In line with this, the transcriptional activation potential of the SRE-binding protein Elk-1 was increased following B-Raf activation. The signal pathway from B-Raf to AP-1 required the activation of c-Jun. We identified the cyclin D1 gene as a delayed response gene for AP-1 following stimulation of B-Raf in insulinoma cells. Moreover, MAP kinase phosphatase-1 and the Ca2+/calmodulin-dependent protein phosphatase calcineurin were identified to function as shut-off-devices for the signaling cascade connecting B-Raf stimulation with the activation of AP-1. The fact that stimulation with glucose, activation of L-type voltage-gated Ca2+ channels, and stimulation of B-Raf all trigger an activation of AP-1 indicates that AP-1 is a point of convergence of signaling pathways in β-cell.
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Affiliation(s)
- Daniel S Langfermann
- Department of Medical Biochemistry and Molecular Biology, Saarland University Medical Faculty, D-66421 Homburg, Germany
| | - Oliver G Rössler
- Department of Medical Biochemistry and Molecular Biology, Saarland University Medical Faculty, D-66421 Homburg, Germany
| | - Gerald Thiel
- Department of Medical Biochemistry and Molecular Biology, Saarland University Medical Faculty, D-66421 Homburg, Germany.
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16
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Eisenhardt AE, Sprenger A, Röring M, Herr R, Weinberg F, Köhler M, Braun S, Orth J, Diedrich B, Lanner U, Tscherwinski N, Schuster S, Dumaz N, Schmidt E, Baumeister R, Schlosser A, Dengjel J, Brummer T. Phospho-proteomic analyses of B-Raf protein complexes reveal new regulatory principles. Oncotarget 2018; 7:26628-52. [PMID: 27034005 PMCID: PMC5042004 DOI: 10.18632/oncotarget.8427] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 03/07/2016] [Indexed: 12/19/2022] Open
Abstract
B-Raf represents a critical physiological regulator of the Ras/RAF/MEK/ERK-pathway and a pharmacological target of growing clinical relevance, in particular in oncology. To understand how B-Raf itself is regulated, we combined mass spectrometry with genetic approaches to map its interactome in MCF-10A cells as well as in B-Raf deficient murine embryonic fibroblasts (MEFs) and B-Raf/Raf-1 double deficient DT40 lymphoma cells complemented with wildtype or mutant B-Raf expression vectors. Using a multi-protease digestion approach, we identified a novel ubiquitination site and provide a detailed B-Raf phospho-map. Importantly, we identify two evolutionary conserved phosphorylation clusters around T401 and S419 in the B-Raf hinge region. SILAC labelling and genetic/biochemical follow-up revealed that these clusters are phosphorylated in the contexts of oncogenic Ras, sorafenib induced Raf dimerization and in the background of the V600E mutation. We further show that the vemurafenib sensitive phosphorylation of the T401 cluster occurs in trans within a Raf dimer. Substitution of the Ser/Thr-residues of this cluster by alanine residues enhances the transforming potential of B-Raf, indicating that these phosphorylation sites suppress its signaling output. Moreover, several B-Raf phosphorylation sites, including T401 and S419, are somatically mutated in tumors, further illustrating the importance of phosphorylation for the regulation of this kinase.
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Affiliation(s)
- Anja E Eisenhardt
- Institute of Molecular Medicine and Cell Research (IMMZ), Faculty of Medicine, Albert-Ludwigs-University (ALU), Freiburg, Germany.,Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Adrian Sprenger
- Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Institute for Experimental and Clinical Pharmacology and Toxicology, ALU, Freiburg, Germany.,INSERM U976 and Universitéi Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Michael Röring
- Institute of Molecular Medicine and Cell Research (IMMZ), Faculty of Medicine, Albert-Ludwigs-University (ALU), Freiburg, Germany.,Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), ALU, Freiburg, Germany
| | - Ricarda Herr
- Institute of Molecular Medicine and Cell Research (IMMZ), Faculty of Medicine, Albert-Ludwigs-University (ALU), Freiburg, Germany.,Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Florian Weinberg
- Institute of Molecular Medicine and Cell Research (IMMZ), Faculty of Medicine, Albert-Ludwigs-University (ALU), Freiburg, Germany.,Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Martin Köhler
- Institute of Molecular Medicine and Cell Research (IMMZ), Faculty of Medicine, Albert-Ludwigs-University (ALU), Freiburg, Germany.,Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), ALU, Freiburg, Germany
| | - Sandra Braun
- Institute of Molecular Medicine and Cell Research (IMMZ), Faculty of Medicine, Albert-Ludwigs-University (ALU), Freiburg, Germany.,Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Joachim Orth
- Institute for Experimental and Clinical Pharmacology and Toxicology, ALU, Freiburg, Germany
| | - Britta Diedrich
- Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Department of Dermatology, University Medical Centre, ALU, Freiburg, Germany
| | - Ulrike Lanner
- Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Natalja Tscherwinski
- Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Simon Schuster
- Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Nicolas Dumaz
- INSERM U976 and Universitéi Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Enrico Schmidt
- Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Ralf Baumeister
- Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Freiburg Institute for Advanced Studies (FRIAS), ALU, Freiburg, Germany.,Centre for Biological Signalling Studies BIOSS, ALU, Freiburg, Germany
| | - Andreas Schlosser
- Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Jörn Dengjel
- Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Department of Dermatology, University Medical Centre, ALU, Freiburg, Germany.,Freiburg Institute for Advanced Studies (FRIAS), ALU, Freiburg, Germany.,Centre for Biological Signalling Studies BIOSS, ALU, Freiburg, Germany.,Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Tilman Brummer
- Institute of Molecular Medicine and Cell Research (IMMZ), Faculty of Medicine, Albert-Ludwigs-University (ALU), Freiburg, Germany.,Institute of Biology III, Faculty of Biology, ALU, Freiburg, Germany.,Centre for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Centre for Biological Signalling Studies BIOSS, ALU, Freiburg, Germany.,German Cancer Consortium (DKTK), Freiburg, Germany
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17
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Thiel G, Rubil S, Lesch A, Guethlein LA, Rössler OG. Transient receptor potential TRPM3 channels: Pharmacology, signaling, and biological functions. Pharmacol Res 2017; 124:92-99. [DOI: 10.1016/j.phrs.2017.07.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/12/2017] [Accepted: 07/12/2017] [Indexed: 12/13/2022]
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18
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Tesselaar MH, Crezee T, Swarts HG, Gerrits D, Boerman OC, Koenderink JB, Stunnenberg HG, Netea MG, Smit JW, Netea-Maier RT, Plantinga TS. Digitalis-like Compounds Facilitate Non-Medullary Thyroid Cancer Redifferentiation through Intracellular Ca2+, FOS, and Autophagy-Dependent Pathways. Mol Cancer Ther 2016; 16:169-181. [DOI: 10.1158/1535-7163.mct-16-0460] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/26/2016] [Accepted: 10/17/2016] [Indexed: 11/16/2022]
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19
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Dernayka L, Rauch N, Jarboui MA, Zebisch A, Texier Y, Horn N, Romano D, Gloeckner CJ, Kriegsheim AV, Ueffing M, Kolch W, Boldt K. Autophosphorylation on S614 inhibits the activity and the transforming potential of BRAF. Cell Signal 2016; 28:1432-1439. [PMID: 27345148 DOI: 10.1016/j.cellsig.2016.06.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 06/09/2016] [Accepted: 06/18/2016] [Indexed: 12/25/2022]
Abstract
The BRAF proto-oncogene serine/threonine-protein kinase, known as BRAF, belongs to the RAF kinase family. It regulates the MAPK/ERK signalling pathway affecting several cellular processes such as growth, survival, differentiation, and cellular transformation. BRAF is mutated in ~8% of all human cancers with the V600E mutation constituting ~90% of mutations. Here, we have used quantitative mass spectrometry to map and compare phosphorylation site patterns between BRAF and BRAF V600E. We identified sites that are shared as well as several quantitative differences in phosphorylation abundance. The highest difference is phosphorylation of S614 in the activation loop which is ~5fold enhanced in BRAF V600E. Mutation of S614 increases the kinase activity of both BRAF and BRAF V600E and the transforming ability of BRAF V600E. The phosphorylation of S614 is mitogen inducible and the result of autophosphorylation. These data suggest that phosphorylation at this site is inhibitory, and part of the physiological shut-down mechanism of BRAF signalling.
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Affiliation(s)
- Layal Dernayka
- Medical Proteome Center, Division for Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Nora Rauch
- Systems Biology Ireland, University College Dublin, Belfield, Dublin 4, Ireland
| | - Mohamed-Ali Jarboui
- Medical Proteome Center, Division for Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Armin Zebisch
- Systems Biology Ireland, University College Dublin, Belfield, Dublin 4, Ireland
| | - Yves Texier
- Medical Proteome Center, Division for Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Nicola Horn
- Medical Proteome Center, Division for Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - David Romano
- Systems Biology Ireland, University College Dublin, Belfield, Dublin 4, Ireland
| | - Christian Johannes Gloeckner
- Medical Proteome Center, Division for Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany; Deutsches Zentrum für Neurodegenerative Erkrankungen e. V., Otfried-Müller Strasse 23, 72076 Tübingen, Germany
| | - Alex von Kriegsheim
- Systems Biology Ireland, University College Dublin, Belfield, Dublin 4, Ireland
| | - Marius Ueffing
- Medical Proteome Center, Division for Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Walter Kolch
- Systems Biology Ireland, University College Dublin, Belfield, Dublin 4, Ireland; Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland; School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland.
| | - Karsten Boldt
- Medical Proteome Center, Division for Experimental Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany.
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20
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Pratt EPS, Salyer AE, Guerra ML, Hockerman GH. Ca2+ influx through L-type Ca2+ channels and Ca2+-induced Ca2+ release regulate cAMP accumulation and Epac1-dependent ERK 1/2 activation in INS-1 cells. Mol Cell Endocrinol 2016; 419:60-71. [PMID: 26435461 PMCID: PMC4684454 DOI: 10.1016/j.mce.2015.09.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 08/28/2015] [Accepted: 09/29/2015] [Indexed: 02/09/2023]
Abstract
We previously reported that INS-1 cells expressing the intracellular II-III loop of the L-type Ca(2+) channel Cav1.2 (Cav1.2/II-III cells) are deficient in Ca(2+)-induced Ca(2+) release (CICR). Here we show that glucose-stimulated ERK 1/2 phosphorylation (GSEP) is slowed and reduced in Cav1.2/II-III cells compared to INS-1 cells. This parallels a decrease in glucose-stimulated cAMP accumulation (GS-cAMP) in Cav1.2/II-III cells. Influx of Ca(2+) via L-type Ca(2+) channels and CICR play roles in both GSEP and GS-cAMP in INS-1 cells since both are inhibited by nicardipine or ryanodine. Further, the Epac1-selective inhibitor CE3F4 abolishes glucose-stimulated ERK activation in INS-1 cells, as measured using the FRET-based sensor EKAR. The non-selective Epac antagonist ESI-09 but not the Epac2-selective antagonist ESI-05 nor the PKA antagonist Rp-cAMPs inhibits GSEP in both INS-1 and Cav1.2/II-III cells. We conclude that L-type Ca(2+) channel-dependent cAMP accumulation, that's amplified by CICR, activates Epac1 and drives GSEP in INS-1 cells.
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Affiliation(s)
- Evan P S Pratt
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA; Purdue University Life Sciences Graduate Program, Purdue University, West Lafayette, IN, USA
| | - Amy E Salyer
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Marcy L Guerra
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA
| | - Gregory H Hockerman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, USA.
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21
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Bedinger DH, Adams SH. Metabolic, anabolic, and mitogenic insulin responses: A tissue-specific perspective for insulin receptor activators. Mol Cell Endocrinol 2015; 415:143-56. [PMID: 26277398 DOI: 10.1016/j.mce.2015.08.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/05/2015] [Accepted: 08/09/2015] [Indexed: 12/17/2022]
Abstract
Insulin acts as the major regulator of the fasting-to-fed metabolic transition by altering substrate metabolism, promoting energy storage, and helping activate protein synthesis. In addition to its glucoregulatory and other metabolic properties, insulin can also act as a growth factor. The metabolic and mitogenic responses to insulin are regulated by divergent post-receptor signaling mechanisms downstream from the activated insulin receptor (IR). However, the anabolic and growth-promoting properties of insulin require tissue-specific inter-relationships between the two pathways, and the nature and scope of insulin-regulated processes vary greatly across tissues. Understanding the nuances of this interplay between metabolic and growth-regulating properties of insulin would have important implications for development of novel insulin and IR modulator therapies that stimulate insulin receptor activation in both pathway- and tissue-specific manners. This review will provide a unique perspective focusing on the roles of "metabolic" and "mitogenic" actions of insulin signaling in various tissues, and how these networks should be considered when evaluating selective pharmacologic approaches to prevent or treat metabolic disease.
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Affiliation(s)
| | - Sean H Adams
- Arkansas Children's Nutrition Center and University of Arkansas for Medical Sciences, Department of Pediatrics, Little Rock, AR, USA
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22
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TRPV6 channel modulates proliferation of insulin secreting INS-1E beta cell line. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3202-10. [PMID: 26384871 DOI: 10.1016/j.bbamcr.2015.09.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 12/21/2022]
Abstract
Transient receptor potential channel vanilloid type 6 (TRPV6) is a non-selective cation channel with high permeability for Ca²⁺ ions. So far, the role of TRPV6 in pancreatic beta cells is unknown. In the present study, we characterized the role of TRPV6 in controlling calcium signaling, cell proliferation as well as insulin expression, and secretion in experimental INS-1E beta cell model. TRPV6 protein production was downregulated using siRNA by approx. 70%, as detected by Western blot. Intracellular free Ca²⁺ ([Ca²⁺]i) was measured by fluorescence Ca²⁺ imaging using fura-2. Calcineurin/NFAT signaling was analyzed using a NFAT reporter assay as well as a calcineurin activity assay. TRPV6 downregulation resulted in impaired cellular calcium influx. Its downregulation also reduced cell proliferation and decreased insulin mRNA expression. These changes were companied by the inhibition of the calcineurin/NFAT signaling. In contrast, insulin exocytosis was not affected by TRPV6 downregulation. In conclusion, this study demonstrates for the first time the expression of TRPV6 in INS-1E cells and rat pancreatic beta cells and describes its role in modulating calcium signaling, beta cell proliferation and insulin mRNA expression. In contrast, TRPV6 fails to influence insulin secretion.
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23
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Wauson EM, Guerra ML, Dyachok J, McGlynn K, Giles J, Ross EM, Cobb MH. Differential Regulation of ERK1/2 and mTORC1 Through T1R1/T1R3 in MIN6 Cells. Mol Endocrinol 2015; 29:1114-22. [PMID: 26168033 DOI: 10.1210/me.2014-1181] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The MAPKs ERK1/2 respond to nutrients and other insulin secretagogues in pancreatic β-cells and mediate nutrient-dependent insulin gene transcription. Nutrients also stimulate the mechanistic target of rapamycin complex 1 (mTORC1) to regulate protein synthesis. We showed previously that activation of both ERK1/2 and mTORC1 in the MIN6 pancreatic β-cell-derived line by extracellular amino acids (AAs) is at least in part mediated by the heterodimeric T1R1/T1R3, a G protein-coupled receptor. We show here that AAs differentially activate these two signaling pathways in MIN6 cells. Pretreatment with pertussis toxin did not prevent the activation of either ERK1/2 or mTORC1 by AAs, indicating that G(I) is not central to either pathway. Although glucagon-like peptide 1, an agonist for a G(s-)coupled receptor, activated ERK1/2 well and mTORC1 to a small extent, AAs had no effect on cytosolic cAMP accumulation. Ca(2+) entry is required for ERK1/2 activation by AAs but is dispensable for AA activation of mTORC1. Pretreatment with UBO-QIC, a selective G(q) inhibitor, reduced the activation of ERK1/2 but had little effect on the activation of mTORC1 by AAs, suggesting a differential requirement for G(q). Inhibition of G(12/13) by the overexpression of the regulator of G protein signaling domain of p115 ρ-guanine nucleotide exchange factor had no effect on mTORC1 activation by AAs, suggesting that these G proteins are also not involved. We conclude that AAs regulate ERK1/2 and mTORC1 through distinct signaling pathways.
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Affiliation(s)
- Eric M Wauson
- Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312
| | - Marcy L Guerra
- Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312
| | - Julia Dyachok
- Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312
| | - Kathleen McGlynn
- Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312
| | - Jennifer Giles
- Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312
| | - Elliott M Ross
- Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312
| | - Melanie H Cobb
- Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312
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Sacco F, Boldt K, Calderone A, Panni S, Paoluzi S, Castagnoli L, Ueffing M, Cesareni G. Combining affinity proteomics and network context to identify new phosphatase substrates and adapters in growth pathways. Front Genet 2014; 5:115. [PMID: 24847354 PMCID: PMC4019850 DOI: 10.3389/fgene.2014.00115] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 04/16/2014] [Indexed: 12/22/2022] Open
Abstract
Protein phosphorylation homoeostasis is tightly controlled and pathological conditions are caused by subtle alterations of the cell phosphorylation profile. Altered levels of kinase activities have already been associated to specific diseases. Less is known about the impact of phosphatases, the enzymes that down-regulate phosphorylation by removing the phosphate groups. This is partly due to our poor understanding of the phosphatase-substrate network. Much of phosphatase substrate specificity is not based on intrinsic enzyme specificity with the catalytic pocket recognizing the sequence/structure context of the phosphorylated residue. In addition many phosphatase catalytic subunits do not form a stable complex with their substrates. This makes the inference and validation of phosphatase substrates a non-trivial task. Here, we present a novel approach that builds on the observation that much of phosphatase substrate selection is based on the network of physical interactions linking the phosphatase to the substrate. We first used affinity proteomics coupled to quantitative mass spectrometry to saturate the interactome of eight phosphatases whose down regulations was shown to affect the activation of the RAS-PI3K pathway. By integrating information from functional siRNA with protein interaction information, we develop a strategy that aims at inferring phosphatase physiological substrates. Graph analysis is used to identify protein scaffolds that may link the catalytic subunits to their substrates. By this approach we rediscover several previously described phosphatase substrate interactions and characterize two new protein scaffolds that promote the dephosphorylation of PTPN11 and ERK by DUSP18 and DUSP26, respectively.
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Affiliation(s)
- Francesca Sacco
- Department of Biology, University of Rome Tor Vergata Rome, Italy
| | - Karsten Boldt
- Division of Experimental Ophthalmology, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen Tuebingen, Germany
| | | | - Simona Panni
- Department DiBEST, University of Calabria Rende, Italy
| | - Serena Paoluzi
- Department of Biology, University of Rome Tor Vergata Rome, Italy
| | - Luisa Castagnoli
- Department of Biology, University of Rome Tor Vergata Rome, Italy
| | - Marius Ueffing
- Division of Experimental Ophthalmology, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen Tuebingen, Germany ; Research Unit for Protein Science, Helmholtz Zentrum München Neuherberg, Germany
| | - Gianni Cesareni
- Department of Biology, University of Rome Tor Vergata Rome, Italy ; Istituto Ricovero e Cura a Carattere Scientifico, Fondazione Santa Lucia Rome, Italy
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25
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Signaling mechanisms of glucose-induced F-actin remodeling in pancreatic islet β cells. Exp Mol Med 2013; 45:e37. [PMID: 23969997 PMCID: PMC3789261 DOI: 10.1038/emm.2013.73] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 06/24/2013] [Indexed: 12/12/2022] Open
Abstract
The maintenance of whole-body glucose homeostasis is critical for survival, and is controlled by the coordination of multiple organs and endocrine systems. Pancreatic islet β cells secrete insulin in response to nutrient stimuli, and insulin then travels through the circulation promoting glucose uptake into insulin-responsive tissues such as liver, skeletal muscle and adipose. Many of the genes identified in human genome-wide association studies of diabetic individuals are directly associated with β cell survival and function, giving credence to the idea that β-cell dysfunction is central to the development of type 2 diabetes. As such, investigations into the mechanisms by which β cells sense glucose and secrete insulin in a regulated manner are a major focus of current diabetes research. In particular, recent discoveries of the detailed role and requirements for reorganization/remodeling of filamentous actin (F-actin) in the regulation of insulin release from the β cell have appeared at the forefront of islet function research, having lapsed in prior years due to technical limitations. Recent advances in live-cell imaging and specialized reagents have revealed localized F-actin remodeling to be a requisite for the normal biphasic pattern of nutrient-stimulated insulin secretion. This review will provide an historical look at the emergent focus on the role of the actin cytoskeleton and its regulation of insulin secretion, leading up to the cutting-edge research in progress in the field today.
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26
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Abstract
Transient receptor potential melastatin 3 (TRPM3) channels are non-selective cation channels that are expressed in insulinoma cells and pancreatic β-cells. Stimulation of TRPM3 with the neurosteroid pregnenolone sulfate induces an intracellular signaling cascade, involving a rise in intracellular Ca(2)(+) concentration, activation of the protein kinases Raf and ERK, and a change in the gene expression pattern of the cells. In particular, biosynthesis of insulin is altered following activation of TRPM3 by pregnenolone sulfate. Moreover, a direct effect of TRPM3 stimulation on insulin secretion has been reported. The fact that stimulation of TRPM3 induces a signaling cascade that is very similar to the signaling cascade induced by glucose in β-cells suggests that TRPM3 may influence main functions of pancreatic β-cells. The view that TRPM3 represents an ionotropic steroid receptor of pancreatic β-cells linking insulin release with steroid hormone signaling is discussed.
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Affiliation(s)
- Gerald Thiel
- Department of Medical Biochemistry and Molecular Biology, University of Saarland Medical Center, Building 44, D-66421 Homburg, Germany.
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27
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Müller I, Lipp P, Thiel G. Ca2+ signaling and gene transcription in glucose-stimulated insulinoma cells. Cell Calcium 2012; 52:137-51. [DOI: 10.1016/j.ceca.2012.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 05/02/2012] [Accepted: 05/04/2012] [Indexed: 10/28/2022]
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28
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Selway J, Rigatti R, Storey N, Lu J, Willars GB, Herbert TP. Evidence that Ca2+ within the microdomain of the L-type voltage gated Ca2+ channel activates ERK in MIN6 cells in response to glucagon-like peptide-1. PLoS One 2012; 7:e33004. [PMID: 22412973 PMCID: PMC3296766 DOI: 10.1371/journal.pone.0033004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Accepted: 02/08/2012] [Indexed: 11/27/2022] Open
Abstract
Glucagon like peptide-1 (GLP-1) is released from intestinal L-cells in response to nutrient ingestion and acts upon pancreatic β-cells potentiating glucose-stimulated insulin secretion and stimulating β-cell proliferation, differentiation, survival and gene transcription. These effects are mediated through the activation of multiple signal transduction pathways including the extracellular regulated kinase (ERK) pathway. We have previously reported that GLP-1 activates ERK through a mechanism dependent upon the influx of extracellular Ca2+ through L-type voltage gated Ca2+ channels (VGCC). However, the mechanism by which L-type VGCCs couple to the ERK signalling pathway in pancreatic β-cells is poorly understood. In this report, we characterise the relationship between L-type VGCC mediated changes in intracellular Ca2+ concentration ([Ca2+]i) and the activation of ERK, and demonstrate that the sustained activation of ERK (up to 30 min) in response to GLP-1 requires the continual activation of the L-type VGCC yet does not require a sustained increase in global [Ca2+]i or Ca2+ efflux from the endoplasmic reticulum. Moreover, sustained elevation of [Ca2+]i induced by ionomycin is insufficient to stimulate the prolonged activation of ERK. Using the cell permeant Ca2+ chelators, EGTA-AM and BAPTA-AM, to determine the spatial dynamics of L-type VGCC-dependent Ca2+ signalling to ERK, we provide evidence that a sustained increase in Ca2+ within the microdomain of the L-type VGCC is sufficient for signalling to ERK and that this plays an important role in GLP-1- stimulated ERK activation.
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Affiliation(s)
- Joanne Selway
- Department of Cell Physiology and Pharmacology, Henry Wellcome Building, University of Leicester, Leicester, United Kingdom
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29
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Osborne JK, Zaganjor E, Cobb MH. Signal control through Raf: in sickness and in health. Cell Res 2011; 22:14-22. [PMID: 22143568 DOI: 10.1038/cr.2011.193] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The extracellular signal-regulated kinase 1/2 (ERK1/2) cascade is the prototype mammalian mitogen-activated protein kinase (MAPK) signaling cascade that regulates a number of processes, including proliferation, differentiation, survival, migration, stress responses and apoptosis. How this seemingly linear cascade is modulated to achieve a specific cellular function has been a main focus of the field. In this review, we describe new as well as old findings in the regulation of the ERK1/2 pathway in normal and disease states via MAP3Ks.
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Affiliation(s)
- Jihan K Osborne
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9041, USA
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30
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Alejandro EU, Lim GE, Mehran AE, Hu X, Taghizadeh F, Pelipeychenko D, Baccarini M, Johnson JD. Pancreatic β-cell Raf-1 is required for glucose tolerance, insulin secretion, and insulin 2 transcription. FASEB J 2011; 25:3884-95. [PMID: 21817126 DOI: 10.1096/fj.10-180349] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Regulation of glucose homeostasis by insulin depends on pancreatic β-cell growth, survival, and function. Raf-1 kinase is a major downstream target of several growth factors that promote proliferation and survival of many cell types, including the pancreatic β cells. We have previously reported that insulin protects β cells from apoptosis and promotes proliferation by activating Raf-1 signaling in cultured human islets, mouse islets, and MIN6 cells. As Raf-1 activity is critical for basal apoptosis and insulin secretion in vitro, we hypothesized that Raf-1 may play an important role in glucose homeostasis in vivo. To test this hypothesis, we utilized the Cre-loxP recombination system to obtain a pancreatic β-cell-specific ablation of Raf-1 kinase gene (RIPCre(+/+):Raf-1(flox/flox)) and a complete set of littermate controls (RIPCre(+/+):Raf-1(wt/wt)). RIPCre(+/+):Raf-1(flox/flox) mice were viable, and no effects on weight gain were observed. RIPCre(+/+):Raf-1(flox/flox) mice had increased fasting blood glucose levels and impaired glucose tolerance but normal insulin tolerance compared to littermate controls. Insulin secretion in vivo and in isolated islets was markedly impaired, but there was no apparent effect on the exocytosis machinery. However, islet insulin protein and insulin 2 mRNA, but not insulin 1 mRNA, were dramatically reduced in Raf-1-knockout mice. Analysis of insulin 2 knockout mice demonstrated that this reduction in mRNA was sufficient to impair in vivo insulin secretion. Our data further indicate that Raf-1 specifically and acutely regulates insulin 2 mRNA via negative action on Foxo1, which has been shown to selectively control the insulin 2 gene. This work provides the first direct evidence that Raf-1 signaling is essential for the regulation of basal insulin transcription and the supply of releasable insulin in vivo.
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Affiliation(s)
- Emilyn U Alejandro
- Laboratory of Molecular Signalling in Diabetes, Diabetes Research Group, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
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