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Trelford CB, Shepherd TG. LKB1 biology: assessing the therapeutic relevancy of LKB1 inhibitors. Cell Commun Signal 2024; 22:310. [PMID: 38844908 PMCID: PMC11155146 DOI: 10.1186/s12964-024-01689-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 05/28/2024] [Indexed: 06/10/2024] Open
Abstract
Liver Kinase B1 (LKB1), encoded by Serine-Threonine Kinase 11 (STK11), is a master kinase that regulates cell migration, polarity, proliferation, and metabolism through downstream adenosine monophosphate-activated protein kinase (AMPK) and AMPK-related kinase signalling. Since genetic screens identified STK11 mutations in Peutz-Jeghers Syndrome, STK11 mutants have been implicated in tumourigenesis labelling it as a tumour suppressor. In support of this, several compounds reduce tumour burden through upregulating LKB1 signalling, and LKB1-AMPK agonists are cytotoxic to tumour cells. However, in certain contexts, its role in cancer is paradoxical as LKB1 promotes tumour cell survival by mediating resistance against metabolic and oxidative stressors. LKB1 deficiency has also enhanced the selectivity and cytotoxicity of several cancer therapies. Taken together, there is a need to develop LKB1-specific pharmacological compounds, but prior to developing LKB1 inhibitors, further work is needed to understand LKB1 activity and regulation. However, investigating LKB1 activity is strenuous as cell/tissue type, mutations to the LKB1 signalling pathway, STE-20-related kinase adaptor protein (STRAD) binding, Mouse protein 25-STRAD binding, splicing variants, nucleocytoplasmic shuttling, post-translational modifications, and kinase conformation impact the functional status of LKB1. For these reasons, guidelines to standardize experimental strategies to study LKB1 activity, associate proteins, spliced isoforms, post-translational modifications, and regulation are of upmost importance to the development of LKB1-specific therapies. Therefore, to assess the therapeutic relevancy of LKB1 inhibitors, this review summarizes the importance of LKB1 in cell physiology, highlights contributors to LKB1 activation, and outlines the benefits and risks associated with targeting LKB1.
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Affiliation(s)
- Charles B Trelford
- The Mary &, John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer Program, 790 Commissioners Road East, Room A4‑921, London, ON, N6A 4L6, Canada.
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.
| | - Trevor G Shepherd
- The Mary &, John Knight Translational Ovarian Cancer Research Unit, London Regional Cancer Program, 790 Commissioners Road East, Room A4‑921, London, ON, N6A 4L6, Canada
- Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- Department of Oncology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
- Department of Obstetrics and Gynaecology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
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Kakoti BB, Alom S, Deka K, Halder RK. AMPK pathway: an emerging target to control diabetes mellitus and its related complications. J Diabetes Metab Disord 2024; 23:441-459. [PMID: 38932895 PMCID: PMC11196491 DOI: 10.1007/s40200-024-01420-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/07/2024] [Indexed: 06/28/2024]
Abstract
Purpose In this extensive review work, the important role of AMP-activated protein kinase (AMPK) in causing of diabetes mellitus has been highlighted. Structural feature of AMPK as well its regulations and roles are described nicely, and the association of AMPK with the diabetic complications like nephropathy, neuropathy and retinopathy are also explained along with the connection between AMPK and β-cell function, insulin resistivity, mTOR, protein metabolism, autophagy and mitophagy and effect on protein and lipid metabolism. Methods Published journals were searched on the database like PubMed, Medline, Scopus and Web of Science by using keywords such as AMPK, diabetes mellitus, regulation of AMPK, complications of diabetes mellitus, autophagy, apoptosis etc. Result After extensive review, it has been found that, kinase enzyme like AMPK is having vital role in management of type II diabetes mellitus. AMPK involve in enhance the concentration of glucose transporter like GLUT 1 and GLUT 4 which result in lowering of blood glucose level in influx of blood glucose into the cells; AMPK increases the insulin sensitivity and decreases the insulin resistance and further AMPK decreases the apoptosis of β-cells which result into secretion of insulin and AMPK is also involve in declining of oxidative stress, lipotoxicity and inflammation, owing to which organ damage due to diabetes mellitus can be lowered by activation of AMPK. Conclusion As AMPK activation leads to overall control of diabetes mellitus, designing and developing of small molecules or peptide that can act as AMPK agonist will be highly beneficial for control or manage diabetes mellitus.
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Affiliation(s)
- Bibhuti B. Kakoti
- Department of Pharmaceutical Sciences, Dibrugarh University, 786004 Dibrugarh, Assam India
| | - Shahnaz Alom
- Department of Pharmaceutical Sciences, Dibrugarh University, 786004 Dibrugarh, Assam India
- Department of Pharmacology, Girijananda Chowdhury Institute of Pharmaceutical Sciences, Girijananda Chowdhury University- Tezpur campus, 784501 Sonitpur, Assam India
| | - Kangkan Deka
- Department of Pharmaceutical Sciences, Dibrugarh University, 786004 Dibrugarh, Assam India
- Department of Pharmacognosy, NETES Institute of Pharmaceutical Science, NEMCARE Group of Institutions, 781125 Mirza, Kamrup, Assam India
| | - Raj Kumar Halder
- Ruhvenile Biomedical, Plot -8 OCF Pocket Institution, Sarita Vihar, 110076 Delhi, India
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Benman W, Huang Z, Iyengar P, Wilde D, Mumford TR, Bugaj LJ. A temperature-inducible protein module for control of mammalian cell fate. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.19.581019. [PMID: 38464222 PMCID: PMC10925237 DOI: 10.1101/2024.02.19.581019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Inducible protein switches are used throughout the biosciences to allow on-demand control of proteins in response to chemical or optical inputs. However, these inducers either cannot be controlled with precision in space and time or cannot be applied in optically dense settings, limiting their application in tissues and organisms. Here we introduce a protein module whose active state can be reversibly toggled with a small change in temperature, a stimulus that is both penetrant and dynamic. This protein, called Melt (Membrane localization through temperature), exists as a monomer in the cytoplasm at elevated temperatures but both oligomerizes and translocates to the plasma membrane when temperature is lowered. Using custom devices for rapid and high-throughput temperature control during live-cell microscopy, we find that the original Melt variant fully switches states between 28-32°C, and state changes can be observed within minutes of temperature changes. Melt was highly modular, permitting thermal control over diverse intracellular processes including signaling, proteolysis, and nuclear shuttling through straightforward end-to-end fusions with no further engineering. Melt was also highly tunable, giving rise to a library of Melt variants with switch point temperatures ranging from 30-40°C. The variants with higher switch points allowed control of molecular circuits between 37°C-41°C, a well-tolerated range for mammalian cells. Finally, Melt could thermally regulate important cell decisions over this range, including cytoskeletal rearrangement and apoptosis. Thus Melt represents a versatile thermogenetic module that provides straightforward, temperature-based, real-time control of mammalian cells with broad potential for biotechnology and biomedicine.
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Affiliation(s)
- William Benman
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Zikang Huang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Pavan Iyengar
- Department of Biophysics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Delaney Wilde
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Thomas R. Mumford
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Lukasz J. Bugaj
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, 19104, USA
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Bansal S, Rahman M, Ravichandran R, Canez J, Fleming T, Mohanakumar T. Extracellular Vesicles in Transplantation: Friend or Foe. Transplantation 2024; 108:374-385. [PMID: 37482627 DOI: 10.1097/tp.0000000000004693] [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] [Indexed: 07/25/2023]
Abstract
The long-term function of transplanted organs, even under immunosuppression, is hindered by rejection, especially chronic rejection. Chronic rejection occurs more frequently after lung transplantation, termed chronic lung allograft dysfunction (CLAD), than after transplantation of other solid organs. Pulmonary infection is a known risk factor for CLAD, as transplanted lungs are constantly exposed to the external environment; however, the mechanisms by which respiratory infections lead to CLAD are poorly understood. The role of extracellular vesicles (EVs) in transplantation remains largely unknown. Current evidence suggests that EVs released from transplanted organs can serve as friend and foe. EVs carry not only major histocompatibility complex antigens but also tissue-restricted self-antigens and various transcription factors, costimulatory molecules, and microRNAs capable of regulating alloimmune responses. EVs play an important role in antigen presentation by direct, indirect, and semidirect pathways in which CD8 and CD4 cells can be activated. During viral infections, exosomes (small EVs <200 nm in diameter) can express viral antigens and regulate immune responses. Circulating exosomes may also be a viable biomarker for other diseases and rejection after organ transplantation. Bioengineering the surface of exosomes has been proposed as a tool for targeted delivery of drugs and personalized medicine. This review focuses on recent studies demonstrating the role of EVs with a focus on exosomes and their dual role (immune activation or tolerance induction) after organ transplantation, more specifically, lung transplantation.
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Affiliation(s)
- Sandhya Bansal
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ
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Stanczyk P, Tatekoshi Y, Shapiro JS, Nayudu K, Chen Y, Zilber Z, Schipma M, De Jesus A, Mahmoodzadeh A, Akrami A, Chang HC, Ardehali H. DNA Damage and Nuclear Morphological Changes in Cardiac Hypertrophy Are Mediated by SNRK Through Actin Depolymerization. Circulation 2023; 148:1582-1592. [PMID: 37721051 PMCID: PMC10840668 DOI: 10.1161/circulationaha.123.066002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 08/23/2023] [Indexed: 09/19/2023]
Abstract
BACKGROUND Proper nuclear organization is critical for cardiomyocyte function, because global structural remodeling of nuclear morphology and chromatin structure underpins the development and progression of cardiovascular disease. Previous reports have implicated a role for DNA damage in cardiac hypertrophy; however, the mechanism for this process is not well delineated. AMPK (AMP-activated protein kinase) family of proteins regulates metabolism and DNA damage response (DDR). Here, we examine whether a member of this family, SNRK (SNF1-related kinase), which plays a role in cardiac metabolism, is also involved in hypertrophic remodeling through changes in DDR and structural properties of the nucleus. METHODS We subjected cardiac-specific Snrk-/- mice to transaortic banding to assess the effect on cardiac function and DDR. In parallel, we modulated SNRK in vitro and assessed its effects on DDR and nuclear parameters. We also used phosphoproteomics to identify novel proteins that are phosphorylated by SNRK. Last, coimmunoprecipitation was used to verify Destrin (DSTN) as the binding partner of SNRK that modulates its effects on the nucleus and DDR. RESULTS Cardiac-specific Snrk-/- mice display worse cardiac function and cardiac hypertrophy in response to transaortic banding, and an increase in DDR marker pH2AX (phospho-histone 2AX) in their hearts. In addition, in vitro Snrk knockdown results in increased DNA damage and chromatin compaction, along with alterations in nuclear flatness and 3-dimensional volume. Phosphoproteomic studies identified a novel SNRK target, DSTN, a member of F-actin depolymerizing factor proteins that directly bind to and depolymerize F-actin. SNRK binds to DSTN, and DSTN downregulation reverses excess DNA damage and changes in nuclear parameters, in addition to cellular hypertrophy, with SNRK knockdown. We also demonstrate that SNRK knockdown promotes excessive actin depolymerization, measured by the increased ratio of G-actin to F-actin. Last, jasplakinolide, a pharmacological stabilizer of F-actin, rescues the increased DNA damage and aberrant nuclear morphology in SNRK-downregulated cells. CONCLUSIONS These results indicate that SNRK is a key player in cardiac hypertrophy and DNA damage through its interaction with DSTN. This interaction fine-tunes actin polymerization to reduce DDR and maintain proper cardiomyocyte nuclear shape and morphology.
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Affiliation(s)
- Paulina Stanczyk
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- These authors contributed equally
| | - Yuki Tatekoshi
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
- These authors contributed equally
| | - Jason S. Shapiro
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
- These authors contributed equally
| | - Krithika Nayudu
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Yihan Chen
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Zachary Zilber
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Matthew Schipma
- Department of Biochemistry and Molecular Genetics, Northwestern University School of Medicine, Chicago, IL, USA
| | - Adam De Jesus
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Amir Mahmoodzadeh
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Ashley Akrami
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Hsiang-Chun Chang
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Hossein Ardehali
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
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Stanczyk P, Tatekoshi Y, Shapiro JS, Nayudu K, Chen Y, Zilber Z, Schipma M, De Jesus A, Mahmoodzadeh A, Akrami A, Chang HC, Ardehali H. DNA damage and nuclear morphological changes in cardiac hypertrophy are mediated by SNRK through actin depolymerization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.14.549060. [PMID: 37503243 PMCID: PMC10370003 DOI: 10.1101/2023.07.14.549060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
BACKGROUND Proper nuclear organization is critical for cardiomyocyte (CM) function, as global structural remodeling of nuclear morphology and chromatin structure underpins the development and progression of cardiovascular disease. Previous reports have implicated a role for DNA damage in cardiac hypertrophy, however, the mechanism for this process is not well delineated. AMPK family of proteins regulate metabolism and DNA damage response (DDR). Here, we examine whether a member of this family, SNF1-related kinase (SNRK), which plays a role in cardiac metabolism, is also involved in hypertrophic remodeling through changes in DDR and structural properties of the nucleus. METHODS We subjected cardiac specific (cs)- Snrk -/- mice to trans-aortic banding (TAC) to assess the effect on cardiac function and DDR. In parallel, we modulated SNRK in vitro and assessed its effects on DDR and nuclear parameters. We also used phospho-proteomics to identify novel proteins that are phosphorylated by SNRK. Finally, co-immunoprecipitation (co-IP) was used to verify Destrin (DSTN) as the binding partner of SNRK that modulates its effects on the nucleus and DDR. RESULTS cs- Snrk -/- mice display worse cardiac function and cardiac hypertrophy in response to TAC, and an increase in DDR marker pH2AX in their hearts. Additionally, in vitro Snrk knockdown results in increased DNA damage and chromatin compaction, along with alterations in nuclear flatness and 3D volume. Phospho-proteomic studies identified a novel SNRK target, DSTN, a member of F-actin depolymerizing factor (ADF) proteins that directly binds to and depolymerize F-actin. SNRK binds to DSTN, and DSTN downregulation reverses excess DNA damage and changes in nuclear parameters, in addition to cellular hypertrophy, with SNRK knockdown. We also demonstrate that SNRK knockdown promotes excessive actin depolymerization, measured by the increased ratio of globular (G-) actin to F-actin. Finally, Jasplakinolide, a pharmacological stabilizer of F-actin, rescues the increased DNA damage and aberrant nuclear morphology in SNRK downregulated cells. CONCLUSIONS These results indicate that SNRK is a key player in cardiac hypertrophy and DNA damage through its interaction with DSTN. This interaction fine-tunes actin polymerization to reduce DDR and maintain proper CM nuclear shape and morphology. Clinical Perspective What is new? Animal hearts subjected to pressure overload display increased SNF1-related kinase (SNRK) protein expression levels and cardiomyocyte specific SNRK deletion leads to aggravated myocardial hypertrophy and heart failure.We have found that downregulation of SNRK impairs DSTN-mediated actin polymerization, leading to maladaptive changes in nuclear morphology, higher DNA damage response (DDR) and increased hypertrophy. What are the clinical implications? Our results suggest that disruption of DDR through genetic loss of SNRK results in an exaggerated pressure overload-induced cardiomyocyte hypertrophy.Targeting DDR, actin polymerization or SNRK/DSTN interaction represent promising therapeutic targets in pressure overload cardiac hypertrophy.
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Affiliation(s)
- Paulina Stanczyk
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- These authors contributed equally
| | - Yuki Tatekoshi
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
- These authors contributed equally
| | - Jason S. Shapiro
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
- These authors contributed equally
| | - Krithika Nayudu
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Yihan Chen
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Zachary Zilber
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Matthew Schipma
- Department of Biochemistry and Molecular Genetics, Northwestern University School of Medicine, Chicago, IL, USA
| | - Adam De Jesus
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Amir Mahmoodzadeh
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Ashley Akrami
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Hsiang-Chun Chang
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
| | - Hossein Ardehali
- Division of Cardiology, Department of Medicine, and Feinberg Cardiovascular and Renal Research Institute, Northwestern University School of Medicine, Chicago, IL, USA
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Rahman M, Ravichandran R, Sankpal NV, Bansal S, Sureshbabu A, Fleming T, Perincheri S, Bharat A, Smith MA, Bremner RM, Mohanakumar T. Downregulation of a tumor suppressor gene LKB1 in lung transplantation as a biomarker for chronic murine lung allograft rejection. Cell Immunol 2023; 386:104690. [PMID: 36812767 PMCID: PMC11019891 DOI: 10.1016/j.cellimm.2023.104690] [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: 11/08/2022] [Revised: 02/07/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023]
Abstract
BACKGROUND We recently demonstrated decreased tumor suppressor gene liver kinase B1 (LKB1) level in lung transplant recipients diagnosed with bronchiolitis obliterans syndrome. STE20-related adaptor alpha (STRADα) functions as a pseudokinase that binds and regulates LKB1 activity. METHODS A murine model of chronic lung allograft rejection in which a single lung from a B6D2F1 mouse was orthotopically transplanted into a DBA/2J mouse was employed. We examined the effect of LKB1 knockdown using CRISPR-CAS9 in vitro culture system. RESULTS Significant downregulation of LKB1 and STRADα expression was found in donor lung compared to recipient lung. STRADα knockdown significantly inhibited LKB1, pAMPK expression but induced phosphorylated mammalian target of rapamycin (mTOR), fibronectin, and Collagen-I, expression in BEAS-2B cells. LKB1 overexpression decreased fibronectin, Collagen-I, and phosphorylated mTOR expression in A549 cells. CONCLUSIONS We demonstrated that downregulation of LKB1-STRADα pathway accompanied with increased fibrosis, results in development of chronic rejection following murine lung transplantation.
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Affiliation(s)
- Mohammad Rahman
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States
| | - Ranjithkumar Ravichandran
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States
| | - Narendra V Sankpal
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States
| | - Sandhya Bansal
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States
| | - Angara Sureshbabu
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States
| | - Timothy Fleming
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States
| | | | - Ankit Bharat
- Northwestern University, Chicago, IL, United States
| | - Michael A Smith
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States
| | - Ross M Bremner
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States
| | - T Mohanakumar
- Norton Thoracic Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, United States.
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Liu Y, Li D, Wang S, Peng Z, Tan Q, He Q, Wang J. 6-Gingerol Ameliorates Hepatic Steatosis, Inflammation and Oxidative Stress in High-Fat Diet-Fed Mice through Activating LKB1/AMPK Signaling. Int J Mol Sci 2023; 24:ijms24076285. [PMID: 37047258 PMCID: PMC10094681 DOI: 10.3390/ijms24076285] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 03/18/2023] [Accepted: 03/25/2023] [Indexed: 03/29/2023] Open
Abstract
6-Gingerol, one of the major pharmacologically active ingredients extracted from ginger, has been reported experimentally to exert hepatic protection in non-alcoholic fatty liver disease (NAFLD). However, the molecular mechanism remains largely elusive. RNA sequencing indicated the significant involvement of the AMPK signaling pathway in 6-gingerol-induced alleviation of NAFLD in vivo. Given the significance of the LKB1/AMPK pathway in metabolic homeostasis, this study aims to investigate its role in 6-gingerol-induced mitigation on NAFLD. Our study showed that 6-gingerol ameliorated hepatic steatosis, inflammation and oxidative stress in vivo and in vitro. Further experiment validation suggested that 6-gingerol activated an LKB1/AMPK pathway cascade in vivo and in vitro. Co-immunoprecipitation analysis demonstrated that the 6-gingerol-elicited activation of an LKB1/AMPK pathway cascade was related to the enhanced stability of the LKB1/STRAD/MO25 complex. Furthermore, radicicol, an LKB1 destabilizer, inhibited the activating effect of 6-gingerol on an LKB1/AMPK pathway cascade via destabilizing LKB1/STRAD/MO25 complex stability in vitro, thus reversing the 6-gingerol-elicited ameliorative effect. In addition, molecular docking analysis further predicated the binding pockets of LKB1 necessary for binding with 6-gingerol. In conclusion, our results indicate that 6-gingerol plays an important role in regulating the stability of the LKB1/STRAD/MO25 complex and the activation of LKB1, which might weigh heavily in the 6-gingerol alleviation of NAFLD.
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Affiliation(s)
- Yuzhe Liu
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic Diseases, College of Traditional Chinese Medicine, Chongqing Medical University, Chongqing 400016, China
- College of Basic Medical Sciences, Chongqing Medical University, Chongqing 400016, China
| | - Dong Li
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic Diseases, College of Traditional Chinese Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Shang Wang
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic Diseases, College of Traditional Chinese Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Ze Peng
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic Diseases, College of Traditional Chinese Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Qi Tan
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic Diseases, College of Traditional Chinese Medicine, Chongqing Medical University, Chongqing 400016, China
| | - Qifeng He
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic Diseases, College of Traditional Chinese Medicine, Chongqing Medical University, Chongqing 400016, China
- College of Basic Medical Sciences, Chongqing Medical University, Chongqing 400016, China
| | - Jianwei Wang
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic Diseases, College of Traditional Chinese Medicine, Chongqing Medical University, Chongqing 400016, China
- Correspondence:
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Borkowsky S, Gass M, Alavizargar A, Hanewinkel J, Hallstein I, Nedvetsky P, Heuer A, Krahn MP. Phosphorylation of LKB1 by PDK1 Inhibits Cell Proliferation and Organ Growth by Decreased Activation of AMPK. Cells 2023; 12:cells12050812. [PMID: 36899949 PMCID: PMC10000615 DOI: 10.3390/cells12050812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 02/24/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023] Open
Abstract
The master kinase LKB1 is a key regulator of se veral cellular processes, including cell proliferation, cell polarity and cellular metabolism. It phosphorylates and activates several downstream kinases, including AMP-dependent kinase, AMPK. Activation of AMPK by low energy supply and phosphorylation of LKB1 results in an inhibition of mTOR, thus decreasing energy-consuming processes, in particular translation and, thus, cell growth. LKB1 itself is a constitutively active kinase, which is regulated by posttranslational modifications and direct binding to phospholipids of the plasma membrane. Here, we report that LKB1 binds to Phosphoinositide-dependent kinase (PDK1) by a conserved binding motif. Furthermore, a PDK1-consensus motif is located within the kinase domain of LKB1 and LKB1 gets phosphorylated by PDK1 in vitro. In Drosophila, knockin of phosphorylation-deficient LKB1 results in normal survival of the flies, but an increased activation of LKB1, whereas a phospho-mimetic LKB1 variant displays decreased AMPK activation. As a functional consequence, cell growth as well as organism size is decreased in phosphorylation-deficient LKB1. Molecular dynamics simulations of PDK1-mediated LKB1 phosphorylation revealed changes in the ATP binding pocket, suggesting a conformational change upon phosphorylation, which in turn can alter LKB1's kinase activity. Thus, phosphorylation of LKB1 by PDK1 results in an inhibition of LKB1, decreased activation of AMPK and enhanced cell growth.
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Affiliation(s)
- Sarah Borkowsky
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149 Münster, Germany
| | - Maximilian Gass
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149 Münster, Germany
| | - Azadeh Alavizargar
- Institute of Physical Chemistry, University of Münster, Corrensstr. 28/30, 48149 Münster, Germany
| | - Johannes Hanewinkel
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149 Münster, Germany
| | - Ina Hallstein
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149 Münster, Germany
| | - Pavel Nedvetsky
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149 Münster, Germany
| | - Andreas Heuer
- Institute of Physical Chemistry, University of Münster, Corrensstr. 28/30, 48149 Münster, Germany
| | - Michael P. Krahn
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149 Münster, Germany
- Correspondence: ; Tel.: +49-251-8357052
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10
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Barriga EH, Alasaadi DN, Mencarelli C, Mayor R, Pichaud F. RanBP1 plays an essential role in directed migration of neural crest cells during development. Dev Biol 2022; 492:79-86. [PMID: 36206829 DOI: 10.1016/j.ydbio.2022.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/15/2022] [Accepted: 09/23/2022] [Indexed: 11/21/2022]
Abstract
Collective cell migration is essential for embryonic development, tissue regeneration and repair, and has been implicated in pathological conditions such as cancer metastasis. It is, in part, directed by external cues that promote front-to-rear polarity in individual cells. However, our understanding of the pathways that underpin the directional movement of cells in response to external cues remains incomplete. To examine this issue we made use of neural crest cells (NC), which migrate as a collective during development to generate vital structures including bones and cartilage. Using a candidate approach, we found an essential role for Ran-binding protein 1 (RanBP1), a key effector of the nucleocytoplasmic transport pathway, in enabling directed migration of these cells. Our results indicate that RanBP1 is required for establishing front-to-rear polarity, so that NCs are able to chemotax. Moreover, our work suggests that RanBP1 function in chemotaxis involves the polarity kinase LKB1/PAR4. We envisage that regulated nuclear export of LKB1 through Ran/RanBP1 is a key regulatory step required for establishing front-to-rear polarity and thus chemotaxis, during NC collective migration.
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Affiliation(s)
- Elias H Barriga
- Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom; Mechanisms of Morphogenesis Lab, Instituto Gulbenkian de Ciencia, Oeiras, 2780-156, Portugal
| | - Delan N Alasaadi
- Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom
| | - Chiara Mencarelli
- Laboratory for Molecular Cell Biology, University College London, London, WC1E 6BT, United Kingdom
| | - Roberto Mayor
- Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom.
| | - Franck Pichaud
- Laboratory for Molecular Cell Biology, University College London, London, WC1E 6BT, United Kingdom.
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11
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Huang E, Li S. Liver Kinase B1 Functions as a Regulator for Neural Development and a Therapeutic Target for Neural Repair. Cells 2022; 11:cells11182861. [PMID: 36139438 PMCID: PMC9496952 DOI: 10.3390/cells11182861] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/02/2022] [Accepted: 09/10/2022] [Indexed: 11/16/2022] Open
Abstract
The liver kinase B1 (LKB1), also known as serine/threonine kinase 11 (STK11) and Par-4 in C. elegans, has been identified as a master kinase of AMPKs and AMPK-related kinases. LKB1 plays a crucial role in cell growth, metabolism, polarity, and tumor suppression. By interacting with the downstream signals of SAD, NUAK, MARK, and other kinases, LKB1 is critical to regulating neuronal polarization and axon branching during development. It also regulates Schwann cell function and the myelination of peripheral axons. Regulating LKB1 activity has become an attractive strategy for repairing an injured nervous system. LKB1 upregulation enhances the regenerative capacity of adult CNS neurons and the recovery of locomotor function in adult rodents with CNS axon injury. Here, we update the major cellular and molecular mechanisms of LKB1 in regulating neuronal polarization and neural development, and the implications thereof for promoting neural repair, axon regeneration, and functional recovery in adult mammals.
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12
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Spatial regulation of AMPK signaling revealed by a sensitive kinase activity reporter. Nat Commun 2022; 13:3856. [PMID: 35790710 PMCID: PMC9256702 DOI: 10.1038/s41467-022-31190-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 06/06/2022] [Indexed: 12/13/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is a master regulator of cellular energetics which coordinates metabolism by phosphorylating a plethora of substrates throughout the cell. But how AMPK activity is regulated at different subcellular locations for precise spatiotemporal control over metabolism is unclear. Here we present a sensitive, single-fluorophore AMPK activity reporter (ExRai AMPKAR), which reveals distinct kinetic profiles of AMPK activity at the mitochondria, lysosome, and cytoplasm. Genetic deletion of the canonical upstream kinase liver kinase B1 (LKB1) results in slower AMPK activity at lysosomes but does not affect the response amplitude at lysosomes or mitochondria, in sharp contrast to the necessity of LKB1 for maximal cytoplasmic AMPK activity. We further identify a mechanism for AMPK activity in the nucleus, which results from cytoplasmic to nuclear shuttling of AMPK. Thus, ExRai AMPKAR enables illumination of the complex subcellular regulation of AMPK signaling.
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13
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Bourouh M, Marignani PA. The Tumor Suppressor Kinase LKB1: Metabolic Nexus. Front Cell Dev Biol 2022; 10:881297. [PMID: 35573694 PMCID: PMC9097215 DOI: 10.3389/fcell.2022.881297] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
Liver kinase B1 (LKB1) is a multitasking tumor suppressor kinase that is implicated in multiple malignancies such as lung, gastrointestinal, pancreatic, and breast. LKB1 was first identified as the gene responsible for Peutz-Jeghers syndrome (PJS) characterized by hamartomatous polyps and oral mucotaneous pigmentation. LKB1 functions to activate AMP-activated protein kinase (AMPK) during energy stress to shift metabolic processes from active anabolic pathways to active catabolic pathways to generate ATP. Genetic loss or inactivation of LKB1 promotes metabolic reprogramming and metabolic adaptations of cancer cells that fuel increased growth and division rates. As a result, LKB1 loss is associated with increased aggressiveness and treatment options for patients with LKB1 mutant tumors are limited. Recently, there has been new insights into the role LKB1 has on metabolic regulation and the identification of potential vulnerabilities in LKB1 mutant tumors. In this review, we discuss the tumor suppressive role of LKB1 and the impact LKB1 loss has on metabolic reprograming in cancer cells, with a focus on lung cancer. We also discuss potential therapeutic avenues to treat malignancies associated with LKB1 loss by targeting aberrant metabolic pathways associated with LKB1 loss.
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Affiliation(s)
- Mohammed Bourouh
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University Halifax, Halifax, NS, Canada
| | - Paola A Marignani
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University Halifax, Halifax, NS, Canada
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14
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Khodadadi M, Jafari-Gharabaghlou D, Zarghami N. An update on mode of action of metformin in modulation of meta-inflammation and inflammaging. Pharmacol Rep 2022; 74:310-322. [PMID: 35067907 DOI: 10.1007/s43440-021-00334-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/11/2021] [Accepted: 10/13/2021] [Indexed: 12/13/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is the most common chronic metabolic condition. Several genetic and environmental factors are involved in developing T2DM. Aging, inflammation, and obesity are the main contributors to the initiation of T2DM. They cause chronic sterile meta-inflammation and insulin resistance, thereby making a person more susceptible to developing T2DM. Metformin, a natural cationic biguanide, is widely used as the first-line treatment of T2DM. The exact action mechanism behind the glucose-lowering effect of metformin is not clear, but, presumably, metformin utilizes a broad spectrum of molecular mechanisms to control blood glucose including decreasing intestinal glucose absorption, inhibition of the hepatic gluconeogenesis, decreasing insulin resistance, etc. Recent studies have shown that metformin exerts its effects through the inhibition of mitochondrial respiratory chain complex 1 and the AMP-activated protein kinase (AMPK) activation, but it has been identified in the other studies that AMPK is not the sole hub in metformin mode of action or there are other unknown mechanisms which are involved and yet to be explored. Therefore, here, we discuss the updated findings of the mechanism of action of metformin that contributes to the meta-inflammation and inflammaging action. It is proposed that figuring out the precise mechanism of action of metformin could improve its application in the fields of obesity, inflammation, aging, and inflammaging.
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Affiliation(s)
- Meysam Khodadadi
- Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Davoud Jafari-Gharabaghlou
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Clinical Biochemistry and Laboratory Medicine, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Nosratollah Zarghami
- Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran. .,Department of Medical Biochemistry, Faculty of Medicine, Istanbul Aydin University, Istanbul, Turkey. .,Department of Clinical Biochemistry and Laboratory Medicine, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
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15
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Koseoglu H, Celebi A, Galamiyeva G, Dalay N, Ozkardes H, Buyru N. No Tumor Suppressor Role for LKB1 in Prostate Cancer. DNA Cell Biol 2021; 40:1222-1229. [PMID: 34370601 DOI: 10.1089/dna.2021.0274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
To elucidate the pathogenesis of prostate diseases, following in silico analysis, the LKB1 gene was selected for further investigation. The LKB1 gene has been associated with poor prognosis and is frequently mutated in different types of cancers. In this study, 50 benign prostatic hyperplasia (BPH) and 57 prostate cancer (PCa) tissues, including matched normal tissue for the patients, were analyzed by qRT-PCR and DNA sequencing for LKB1 expression and the mutation profile, respectively. Expression of LKB1 was increased in 60.7% of the PCa tissues compared with noncancerous tissue samples (p ≤ 0.001). However, LKB1 expression was lower when compared with normal tissues in BPH (p = 0.920). Four coding sequence alterations were detected in BPH. Three silent mutations were located in codons 9, 32, and 275 and a missense mutation was observed in codon 384. Six alterations were identified in the intronic regions of the LKB1 gene in both PCa and BPH. Five mutations were observed in both patient groups. A new alteration in intron 6 was observed in a patient with PCa. The LKB1 gene may be associated with benign transformations rather than the tumors in prostate pathogenesis when its expression and mutation status are considered. However, the mechanism of LKB1 in PCa needs further studies.
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Affiliation(s)
- Hikmet Koseoglu
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Asuman Celebi
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Gunay Galamiyeva
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Nejat Dalay
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Hakan Ozkardes
- Department of Urology, Medical Faculty, Baskent University, Istanbul, Turkey
| | - Nur Buyru
- Department of Medical Biology, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
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16
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Markiewicz Ł, Uśpieński T, Baran B, Niedziółka SM, Niewiadomski P. Xpo7 negatively regulates Hedgehog signaling by exporting Gli2 from the nucleus. Cell Signal 2021; 80:109907. [PMID: 33383157 DOI: 10.1016/j.cellsig.2020.109907] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/22/2020] [Accepted: 12/27/2020] [Indexed: 01/01/2023]
Abstract
Dynamic bidirectional transport between the nucleus and the cytoplasm is critical for the regulation of many transcription factors, whose levels inside the nucleus must be tightly controlled. Efficient shuttling across the nuclear membrane is especially crucial with regard to the Hedgehog (Hh) pathway, where the transcriptional signal depends on the fine balance between the amounts of Gli protein activator and repressor forms in the nucleus. The nuclear export machinery prevents the unchecked nuclear accumulation of Gli proteins, but the mechanistic insight into this process is limited. We show that the atypical exportin Xpo7 functions as a major nuclear export receptor that actively excludes Gli2 from the nucleus and controls the outcome of Hh signaling. We show that Xpo7 interacts with several domains of Gli2 and that this interaction is modulated by SuFu, a key negative regulator of Hh signaling. Our data pave the way for a more complete understanding of the nuclear shuttling of Gli proteins and the regulation of their transcriptional activity.
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Affiliation(s)
- Łukasz Markiewicz
- Laboratory of Molecular and Cellular Signaling, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Tomasz Uśpieński
- Laboratory of Molecular and Cellular Signaling, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Brygida Baran
- Laboratory of Molecular and Cellular Signaling, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Sylwia M Niedziółka
- Laboratory of Molecular and Cellular Signaling, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland
| | - Paweł Niewiadomski
- Laboratory of Molecular and Cellular Signaling, Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland.
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17
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Granado-Martínez P, Garcia-Ortega S, González-Sánchez E, McGrail K, Selgas R, Grueso J, Gil R, Naldaiz-Gastesi N, Rhodes AC, Hernandez-Losa J, Ferrer B, Canals F, Villanueva J, Méndez O, Espinosa-Gil S, Lizcano JM, Muñoz-Couselo E, García-Patos V, Recio JA. STK11 (LKB1) missense somatic mutant isoforms promote tumor growth, motility and inflammation. Commun Biol 2020; 3:366. [PMID: 32647375 PMCID: PMC7347935 DOI: 10.1038/s42003-020-1092-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Accepted: 06/19/2020] [Indexed: 02/07/2023] Open
Abstract
Elucidating the contribution of somatic mutations to cancer is essential for personalized medicine. STK11 (LKB1) appears to be inactivated in human cancer. However, somatic missense mutations also occur, and the role/s of these alterations to this disease remain unknown. Here, we investigated the contribution of four missense LKB1 somatic mutations in tumor biology. Three out of the four mutants lost their tumor suppressor capabilities and showed deficient kinase activity. The remaining mutant retained the enzymatic activity of wild type LKB1, but induced increased cell motility. Mechanistically, LKB1 mutants resulted in differential gene expression of genes encoding vesicle trafficking regulating molecules, adhesion molecules and cytokines. The differentially regulated genes correlated with protein networks identified through comparative secretome analysis. Notably, three mutant isoforms promoted tumor growth, and one induced inflammation-like features together with dysregulated levels of cytokines. These findings uncover oncogenic roles of LKB1 somatic mutations, and will aid in further understanding their contributions to cancer development and progression. Paula Granado-Martínez, Sara Ortega, Elena González-Sánchez et al. report a functional analysis of four cancer-associated mutant isoforms of the gene STK11 using cell-based and animal models. They find the mutant isoforms no longer show tumor suppressor activity, promote tumor growth, and affect the regulation of cytokines and genes involved in vesicle trafficking.
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Affiliation(s)
- Paula Granado-Martínez
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Sara Garcia-Ortega
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Elena González-Sánchez
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Kimberley McGrail
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Rafael Selgas
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Judit Grueso
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain.,Experimental Therapeutics Group, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, 08035, Spain
| | - Rosa Gil
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Neia Naldaiz-Gastesi
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain.,Biodonostia, Neurosciences Area, Group of Neuromuscular Diseases, San Sebastian, 20014, Spain
| | - Ana C Rhodes
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain.,Barcelona Clinic Liver Cancer (BCLC) Group, Liver Unit, Hospital Clínic of Barcelona, University of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, 08036, Spain
| | - Javier Hernandez-Losa
- Anatomy Pathology Department, Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Berta Ferrer
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain.,Anatomy Pathology Department, Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Francesc Canals
- Proteomics Laboratory, Vall d'Hebron Institute of Oncology (VHIO, Barcelona, 08035, Spain
| | - Josep Villanueva
- Preclinical Research Program, Vall d'Hebron Institute of Oncology (VHIO, Barcelona, 08035, Spain
| | - Olga Méndez
- Preclinical Research Program, Vall d'Hebron Institute of Oncology (VHIO, Barcelona, 08035, Spain
| | - Sergio Espinosa-Gil
- Protein Kinases and Signal Transduction Laboratory, Neuroscience Institute and Molecular Biology and Biochemistry Department, UAB, Bellaterra, Barcelona, 08193, Spain
| | - José M Lizcano
- Protein Kinases and Signal Transduction Laboratory, Neuroscience Institute and Molecular Biology and Biochemistry Department, UAB, Bellaterra, Barcelona, 08193, Spain
| | - Eva Muñoz-Couselo
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain.,Clinical Oncology Program, Vall d'Hebron Institute of Oncology (VHIO), Vall d'Hebron Hospital, Barcelona-UAB, Barcelona, 08035, Spain
| | - Vicenç García-Patos
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain.,Dermatology Department, Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain
| | - Juan A Recio
- Biomedical Research in Melanoma-Animal Models and Cancer Laboratory- Vall d'Hebron Research Institute VHIR-Vall d'Hebron Hospital Barcelona-UAB, Barcelona, 08035, Spain.
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18
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Jiang Q, Gu S. Sevoflurane Postconditioning Reduces Hypoxia-Reoxygenation Injury in H9C2 Embryonic Rat Cardiomyocytes and Targets the STRADA Gene by Upregulating microRNA-107. Med Sci Monit 2020; 26:e920849. [PMID: 32332694 PMCID: PMC7197225 DOI: 10.12659/msm.920849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Sevoflurane as a widely used inhalational general anesthetic that also has a cardioprotective role in hypoxia-reoxygenation (H/R) injury. This study aimed to investigate the effects of microRNA-107 (miR-107) on sevoflurane postconditioning (SpostC) in H9C2 embryonic rat cardiomyocytes and to use bioinformatics analysis to identify the molecular basis of cardioprotection from sevoflurane in human cardiac tissue. MATERIAL AND METHODS The STRADA gene was identified from the Gene Expression Omnibus (GEO) database. H9C2 embryonic rat cardiomyocytes were cultured with sevoflurane. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to measure the mRNA expression and protein expression of STRADA and miR-107 in H9C2 cells. TargetScanHuman version 7.2 was used to identify the target gene of miR-107 and to predict the STRADA 3'-UTR binding site of miR-107. The dual-luciferase reporter assay measured the relative luciferase activity. The cell proliferation rate and cell apoptosis were measured using the MTT assay and flow cytometry, respectively. RESULTS H/R injury in H9C2 cells following SpostC resulted in increased expression of miR-107 and reduced expression of STRADA. Specific binding of miR-107 was identified to STRADA 3'-UTR. Upregulation of the miR-107 in SpostC H/R injured H9C2 cells promoted cell proliferation, reduced cell apoptosis, and downregulating the protein expression of caspase-3. STRADA overexpression reduced the effects of a miR-107 mimic on SpostC. CONCLUSIONS SpostC reduced H/R injury in H9C2 embryonic rat cardiomyocytes by targeting the STRADA gene and by upregulating the expression of microRNA-107.
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Affiliation(s)
- Qun Jiang
- Department of Pain Medicine, Affiliated Hospital of Jianghan University, Wuhan, Hubei, China (mainland)
| | - Shan Gu
- Department of Anesthesiology, Hubei Provincial Hospital of Traditional Chinese Medicine, Wuhan, Hubei, China (mainland).,Hubei Province Academy of Traditional Chinese Medicine, Wuhan, Hubei, China (mainland)
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19
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Chauhan AS, Zhuang L, Gan B. Spatial control of AMPK signaling at subcellular compartments. Crit Rev Biochem Mol Biol 2020; 55:17-32. [PMID: 32069425 DOI: 10.1080/10409238.2020.1727840] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AMP-activated protein kinase (AMPK) is a master regulator of energy homeostasis that functions to restore the energy balance by phosphorylating its substrates during altered metabolic conditions. AMPK activity is tightly controlled by diverse regulators including its upstream kinases LKB1 and CaMKK2. Recent studies have also identified the localization of AMPK at different intracellular compartments as another key mechanism for regulating AMPK signaling in response to specific stimuli. This review discusses the AMPK signaling associated with different subcellular compartments, including lysosomes, endoplasmic reticulum, mitochondria, Golgi apparatus, nucleus, and cell junctions. Because altered AMPK signaling is associated with various pathologic conditions including cancer, targeting AMPK signaling in different subcellular compartments may present attractive therapeutic approaches for treatment of disease.
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Affiliation(s)
- Anoop Singh Chauhan
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Li Zhuang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Boyi Gan
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Health Graduate School of Biomedical Sciences, The University of Texas MD Anderson UT, Houston, TX, USA
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20
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Kari S, Vasko VV, Priya S, Kirschner LS. PKA Activates AMPK Through LKB1 Signaling in Follicular Thyroid Cancer. Front Endocrinol (Lausanne) 2019; 10:769. [PMID: 31798532 PMCID: PMC6874117 DOI: 10.3389/fendo.2019.00769] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 10/23/2019] [Indexed: 01/08/2023] Open
Abstract
Thyroid cancer affects about one percent of the population, and has seen rising incidence in recent years. Follicular thyroid cancer (FTC) comprises 10-15% of all thyroid cancers. Although FTC is often localized, it can behave aggressively with hematogenous metastasis, leading to an increased risk of cancer death. We previously described a mouse model for FTC caused by tissue-specific ablation of the Protein Kinase A (PKA) regulatory subunit Prkar1a, either by itself or in combination with knockout of Pten. Loss of Prkar1a causes enhanced activity of PKA, whereas ablation of Pten causes activation of Akt signaling. At the molecular level, these genetic manipulations caused activation of mTOR signaling, which was also observed in human FTC cases. To understand the mechanism by which PKA activates mTOR, we began by studying intracellular kinases known to modulate mTOR function. Although AMP-activated kinase (AMPK) has been characterized as a negative regulator of mTOR activity, our tumor model exhibited activation of both AMPK and mTOR. To understand the mechanism by which AMPK was turned on, we next studied kinases known to cause its phosphorylation. In this paper, we report that PKA leads to AMPK activation through the LKB1 kinase. Although LKB1 has traditionally been considered a tumor suppressor, our data indicates that it may have a complex role in the thyroid gland, where its activation appears to be frequently associated with follicular thyroid carcinoma in both mice and humans.
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Affiliation(s)
- Suresh Kari
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
| | - Vasyl V. Vasko
- Uniformed Services University of Health Sciences, Bethesda, MD, United States
| | - Shivam Priya
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
| | - Lawrence S. Kirschner
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, The Ohio State University, Columbus, OH, United States
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21
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Delgado TC, Lopitz-Otsoa F, Martínez-Chantar ML. Post-translational modifiers of liver kinase B1/serine/threonine kinase 11 in hepatocellular carcinoma. J Hepatocell Carcinoma 2019; 6:85-91. [PMID: 31240204 PMCID: PMC6560252 DOI: 10.2147/jhc.s169585] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/24/2019] [Indexed: 12/16/2022] Open
Abstract
Liver kinase B1 (LKB1) also referred to as serine/threonine kinase 11 (STK11) encodes a 50 kDa evolutionary conserved serine/threonine kinase that is ubiquitously expressed in adult and fetal tissues. LKB1 is a master kinase known to phosphorylate and activate several kinases including AMP-activated protein kinase, a crucial cellular energy sensor. LKB1 shows pleiotropic activity playing diverse roles in multiple processes, including cell polarity and other processes relevant in cancer pathology, such as energy metabolism, proliferation and apoptosis. In spite of the fact that LKB1 is often considered a tumor suppressor in a wide variety of organs, in the last years, several studies have shown that LKB1 is unexpectedly high in hepatocellular carcinoma (HCC), the most common type of primary liver cancer. Post-translational modifications of LKB1 are potentially relevant in HCC. Herein, we provide a comprehensive revision of post-translational modifications of LKB1 in HCC and how they modulate LKB1 function by different mechanisms such as regulation of its activity, localization or stability. Overall, the signature post-translational modifications of LKB1 in HCC appear to play an important role in the rather unique role of LKB1 as an oncogenic driver in liver cancer and may provide an alternative valuable therapeutic approach to regulate LKB1 expression and/or activity in HCC. ![]()
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Affiliation(s)
- Teresa Cardoso Delgado
- Liver Disease and Liver Metabolism Laboratories, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Derio 48160, Bizkaia, Spain
| | - Fernando Lopitz-Otsoa
- Liver Disease and Liver Metabolism Laboratories, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Derio 48160, Bizkaia, Spain
| | - María Luz Martínez-Chantar
- Liver Disease and Liver Metabolism Laboratories, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Derio 48160, Bizkaia, Spain
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Zubiete-Franco I, García-Rodríguez JL, Lopitz-Otsoa F, Serrano-Macia M, Simon J, Fernández-Tussy P, Barbier-Torres L, Fernández-Ramos D, Gutiérrez-de-Juan V, López de Davalillo S, Carlevaris O, Beguiristain Gómez A, Villa E, Calvisi D, Martín C, Berra E, Aspichueta P, Beraza N, Varela-Rey M, Ávila M, Rodríguez MS, Mato JM, Díaz-Moreno I, Díaz-Quintana A, Delgado TC, Martínez-Chantar ML. SUMOylation regulates LKB1 localization and its oncogenic activity in liver cancer. EBioMedicine 2018; 40:406-421. [PMID: 30594553 PMCID: PMC6412020 DOI: 10.1016/j.ebiom.2018.12.031] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 12/13/2018] [Accepted: 12/14/2018] [Indexed: 02/06/2023] Open
Abstract
Background Even though liver kinase B1 (LKB1) is usually described as a tumor suppressor in a wide variety of tissues, it has been shown that LKB1 aberrant expression is associated with bad prognosis in Hepatocellular Carcinoma (HCC). Methods Herein we have overexpressed LKB1 in human hepatoma cells and by using histidine pull-down assay we have investigated the role of the hypoxia-related post-translational modification of Small Ubiquitin-related Modifier (SUMO)ylation in the regulation of LKB1 oncogenic role. Molecular modelling between LKB1 and its interactors, involved in regulation of LKB1 nucleocytoplasmic shuttling and LKB1 activity, was performed. Finally, high affinity SUMO binding entities-based technology were used to validate our findings in a pre-clinical mouse model and in clinical HCC. Findings We found that in human hepatoma cells under hypoxic stress, LKB1 overexpression increases cell viability and aggressiveness in association with changes in LKB1 cellular localization. Moreover, by using site-directed mutagenesis, we have shown that LKB1 is SUMOylated by SUMO-2 at Lys178 hampering LKB1 nucleocytoplasmic shuttling and fueling hepatoma cell growth. Molecular modelling of SUMO modified LKB1 further confirmed steric impedance between SUMOylated LKB1 and the STe20-Related ADaptor cofactor (STRADα), involved in LKB1 export from the nucleus. Finally, we provide evidence that endogenous LKB1 is modified by SUMO in pre-clinical mouse models of HCC and clinical HCC, where LKB1 SUMOylation is higher in fast growing tumors. Interpretation Overall, SUMO-2 modification of LKB1 at Lys178 mediates LKB1 cellular localization and its oncogenic role in liver cancer. Fund This work was supported by grants from NIH (US Department of Health and Human services)-R01AR001576-11A1 (J.M.M and M.L.M-C.), Gobierno Vasco-Departamento de Salud 2013111114 (to M.L.M.-C), ELKARTEK 2016, Departamento de Industria del Gobierno Vasco (to M.L.M.-C), MINECO: SAF2017–87301-R and SAF2014–52097-R integrado en el Plan Estatal de Investigación Cientifica y Técnica y Innovación 2013–2016 cofinanciado con Fondos FEDER (to M.L.M.-C and J.M.M., respectively), BFU2015–71017/BMC MINECO/FEDER, EU (to A.D.Q. and I.D.M.), BIOEF (Basque Foundation for Innovation and Health Research): EITB Maratoia BIO15/CA/014; Instituto de Salud Carlos III:PIE14/00031, integrado en el Plan Estatal de Investigación Cientifica y Técnica y Innovacion 2013–2016 cofinanciado con Fondos FEDER (to M.L.M.-C and J.M.M), Asociación Española contra el Cáncer (T.C.D, P·F-T and M.L.M-C), Daniel Alagille award from EASL (to T.C.D), Fundación Científica de la Asociación Española Contra el Cancer (AECC Scientific Foundation) Rare Tumor Calls 2017 (to M.L.M and M.A), La Caixa Foundation Program (to M.L.M), Programma di Ricerca Regione-Università 2007–2009 and 2011–2012, Regione Emilia-Romagna (to E.V.), Ramón Areces Foundation and the Andalusian Government (BIO-198) (A.D.Q. and I.D.M.), ayudas para apoyar grupos de investigación del sistema Universitario Vasco IT971–16 (P.A.), MINECO:SAF2015–64352-R (P.A.), Institut National du Cancer, FRANCE, INCa grant PLBIO16–251 (M.S.R.), MINECO - BFU2016–76872-R to (E.B.). Work produced with the support of a 2017 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation (M.V-R). Finally, Ciberehd_ISCIII_MINECO is funded by the Instituto de Salud Carlos III. We thank MINECO for the Severo Ochoa Excellence Accreditation to CIC bioGUNE (SEV-2016-0644). Funding sources had no involvement in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication. Overexpression of LKB1 in human hepatoma cells during hypoxic stress induces deregulated cell growth and survival. SUMO-2 modifications of LKB1 at Lys178 occur in human hepatoma cells hampering its nucleocytoplasmic shuttling. LKB1 SUMOylation is augmented in pre-clinical mouse models and clinical HCC, being a hallmark of more aggressive HCC tumors.
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Affiliation(s)
- Imanol Zubiete-Franco
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Juan L García-Rodríguez
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Fernando Lopitz-Otsoa
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Marina Serrano-Macia
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Jorge Simon
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Pablo Fernández-Tussy
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Lucía Barbier-Torres
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - David Fernández-Ramos
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Virginia Gutiérrez-de-Juan
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Sergio López de Davalillo
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Onintza Carlevaris
- Physiopathology of the Hypoxia-Signalling Pathway Lab, CIC bioGUNE, 48160 Derio, Bizkaia, Spain
| | | | - Erica Villa
- Department of Gastroenterology, Azienda Ospedaliero-Universitaria & University of Modena and Reggio Emilia, 41124 Modena, Italy
| | - Diego Calvisi
- Institute of Pathology, University Klinic of Regensburg, 93053 Regensburg, Germany
| | - César Martín
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, UPV/EHU, 48940 Leioa, Spain
| | - Edurne Berra
- Physiopathology of the Hypoxia-Signalling Pathway Lab, CIC bioGUNE, 48160 Derio, Bizkaia, Spain
| | - Patricia Aspichueta
- Department of Physiology, Faculty of Medicine and Nursing, University of the Basque Country, 48940 Leioa, Bizkaia, Spain; Biocruces Health Research Institute, 48093 Barakaldo, Bizkaia, Spain
| | - Naiara Beraza
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Marta Varela-Rey
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Matias Ávila
- Hepatology Department, Centro de Investigación Médica Aplicada (CIMA), Universidad de Navarra, 31008 Pamplona, Spain
| | - Manuel S Rodríguez
- UbiCARE, Advanced Technology Institute in Life Sciences (ITAV)-CNRS-IPBS, 31106 Toulouse, France
| | - José M Mato
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain
| | - Irene Díaz-Moreno
- Instituto de Investigaciones Químicas (IIQ) - Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - Consejo Superior de Investigaciones Científicas (CSIC), 41092 Sevilla, Spain
| | - Antonio Díaz-Quintana
- Instituto de Investigaciones Químicas (IIQ) - Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - Consejo Superior de Investigaciones Científicas (CSIC), 41092 Sevilla, Spain
| | - Teresa C Delgado
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain.
| | - María L Martínez-Chantar
- Liver Disease and Liver Metabolism Lab, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), 48160 Derio, Bizkaia, Spain.
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Mencarelli C, Nitarska J, Kroecher T, Ferraro F, Massey K, Riccio A, Pichaud F. RanBP1 Couples Nuclear Export and Golgi Regulation through LKB1 to Promote Cortical Neuron Polarity. Cell Rep 2018; 24:2529-2539.e4. [PMID: 30184488 PMCID: PMC6137820 DOI: 10.1016/j.celrep.2018.07.107] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 06/06/2018] [Accepted: 07/30/2018] [Indexed: 11/18/2022] Open
Abstract
Neuronal polarity in the developing cortex begins during the early stages of neural progenitor migration toward the cortical plate and culminates with the specification of the axon and dendrites. Here, we demonstrate that the Ran-dependent nucleocytoplasmic transport machinery is essential for the establishment of cortical neuron polarity. We found that Ran-binding protein 1 (RanBP1) regulates axon specification and dendritic arborization in cultured neurons in vitro and radial neural migration in vivo. During axonogenesis, RanBP1 regulates the cytoplasmic levels of the polarity protein LKB1/Par4, and this is dependent on the nuclear export machinery. Our results show that downstream of RanBP1, LKB1 function is mediated by the STK25-GM130 pathway, which promotes axonogenesis through Golgi regulation. Our results indicate that the nucleocytoplasmic transport machinery is a main regulator of neuron polarity, including radial migration, and that the regulated export of LKB1 through RanBP1 is a limiting step of axonogenesis.
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Affiliation(s)
- Chiara Mencarelli
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Justyna Nitarska
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Tim Kroecher
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Francesco Ferraro
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Katherine Massey
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Antonella Riccio
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Franck Pichaud
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK.
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Abstract
The tumor suppressor LKB1 is an essential serine/threonine kinase, which regulates various cellular processes such as cell metabolism, cell proliferation, cell polarity, and cell migration. Germline mutations in the STK11 gene (encoding LKB1) are the cause of the Peutz-Jeghers syndrome, which is characterized by benign polyps in the intestine and a higher risk for the patients to develop intestinal and extraintestinal tumors. Moreover, mutations and misregulation of LKB1 have been reported to occur in most types of tumors and are among the most common aberrations in lung cancer. LKB1 activates several downstream kinases of the AMPK family by direct phosphorylation in the T-loop. In particular the activation of AMPK upon energetic stress has been intensively analyzed in various diseases, including cancer to induce a metabolic switch from anabolism towards catabolism to regulate energy homeostasis and cell survival. In contrast, the regulation of LKB1 itself has long been only poorly understood. Only in the last years, several proteins and posttranslational modifications of LKB1 have been analyzed to control its localization, activity and recognition of substrates. Here, we summarize the current knowledge about the upstream regulation of LKB1, which is important for the understanding of the pathogenesis of many types of tumors.
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Karyopherins in cancer. Curr Opin Cell Biol 2018; 52:30-42. [PMID: 29414591 DOI: 10.1016/j.ceb.2018.01.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/08/2018] [Accepted: 01/14/2018] [Indexed: 12/16/2022]
Abstract
Malfunction of nuclear-cytoplasmic transport contributes to many diseases including cancer. Defective nuclear transport leads to changes in both the physiological levels and temporal-spatial location of tumor suppressors, proto-oncogenes and other macromolecules that in turn affect the tumorigenesis process and drug sensitivity of cancer cells. In addition to their nuclear transport functions in interphase, Karyopherin nuclear transport receptors also have important roles in mitosis and chromosomal integrity. Therefore, alterations in the expressions or regular functions of Karyopherins may have substantial effects on the course and outcome of diseases.
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Bai B, Man AWC, Yang K, Guo Y, Xu C, Tse HF, Han W, Bloksgaard M, De Mey JGR, Vanhoutte PM, Xu A, Wang Y. Endothelial SIRT1 prevents adverse arterial remodeling by facilitating HERC2-mediated degradation of acetylated LKB1. Oncotarget 2018; 7:39065-39081. [PMID: 27259994 PMCID: PMC5129914 DOI: 10.18632/oncotarget.9687] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/23/2016] [Indexed: 11/25/2022] Open
Abstract
Aims-SIRT1 exerts potent activity against cellular senescence and vascular ageing. By decreasing LKB1 protein levels, it promotes the survival and regeneration of endothelial cells. The present study aims to investigate the molecular mechanisms underlying SIRT1-mediated LKB1 degradation for the prevention of vascular ageing. Methods and Results-Co-immunoprecipitation assay demonstrated that SIRT1, via its amino-terminus, binds to the DOC domain of HERC2 [HECT and RLD domain containing E3 ubiquitin protein ligase 2], which then ubiquitinates LKB1 in the nuclear compartment of endothelial cells. Site-directed mutagenesis revealed that acetylation at lysine (K) 64 of LKB1 triggers the formation of SIRT1/HERC2/LKB1 protein complex and subsequent proteasomal degradation. In vitro cellular studies suggested that accumulation of acetylated LKB1 in the nucleus leads to endothelial activation, in turn stimulating the proliferation of vascular smooth muscle cells and the production of extracellular matrix proteins. Chromatin immunoprecipitation quantitative PCR confirmed that acetylated LKB1 interacts with and activates TGFβ1 promoter, which is inhibited by SIRT1. Knocking down either SIRT1 or HERC2 results in an increased association of LKB1 with the positive regulatory elements of TGFβ1 promoter. In mice without endothelial nitric oxide synthase, selective overexpression of human SIRT1 in endothelium prevents hypertension and age-related adverse arterial remodeling. Lentiviral-mediated knockdown of HERC2 abolishes the beneficial effects of endothelial SIRT1 on both arterial remodeling and arterial blood pressure control. Conclusion-By downregulating acetylated LKB1 protein via HERC2, SIRT1 fine-tunes the crosstalk between endothelial and vascular smooth muscle cells to prevent adverse arterial remodeling and maintain vascular homeostasis.
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Affiliation(s)
- Bo Bai
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China.,Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Andy W C Man
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
| | - Kangmin Yang
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
| | - Yumeng Guo
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
| | - Cheng Xu
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
| | - Hung-Fat Tse
- Department of Medicine, The University of Hong Kong, Hong Kong, China
| | - Weiping Han
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Maria Bloksgaard
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Jo G R De Mey
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Paul M Vanhoutte
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
| | - Aimin Xu
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China.,Department of Medicine, The University of Hong Kong, Hong Kong, China
| | - Yu Wang
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
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Aurora-A-mediated phosphorylation of LKB1 compromises LKB1/AMPK signaling axis to facilitate NSCLC growth and migration. Oncogene 2017; 37:502-511. [PMID: 28967900 DOI: 10.1038/onc.2017.354] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 08/04/2017] [Accepted: 08/16/2017] [Indexed: 12/16/2022]
Abstract
Deletion or loss-of-function mutation of LKB1, frequently occurring in non-small cell lung cancers (NSCLCs), is a predominant caution of NSCLC initiation and progression. However, the upstream signaling pathways governing LKB1 activation are largely unknown. Here, we report that LKB1 undergoes Aurora kinase A (AURKA)-mediated phosphorylation, which largely compromises the LKB1/AMPK signaling axis, in turn leading to the elevation of NSCLC cell proliferation, invasion and migration. Mechanically, AURKA-mediated phosphorylation of LKB1 impairs LKB1 interaction with and phosphorylation of its downstream target AMPKα, which has critical roles in governing cancer cell energy metabolic homeostasis and tumorigenesis. Clinically, AURKA displays high levels in NSCLC patients, and correlates with poor outcome of patients with lung adenocarcinoma. Pathologically, the amplification or activation of AURKA-induced impairment of the LKB1/AMPK signaling pathway contributes to NSCLC initiation and progression, highlighting AURKA as a potential therapeutic target for combatting hyperactive AURKA-driven NSCLCs.
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Membrane-binding and activation of LKB1 by phosphatidic acid is essential for development and tumour suppression. Nat Commun 2017. [PMID: 28649994 PMCID: PMC5490199 DOI: 10.1038/ncomms15747] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The serine/threonine kinase LKB1 regulates various cellular processes such as cell proliferation, energy homeostasis and cell polarity and is frequently downregulated in various tumours. Many downstream pathways controlled by LKB1 have been described but little is known about the upstream regulatory mechanisms. Here we show that targeting of the kinase to the membrane by a direct binding of LKB1 to phosphatidic acid is essential to fully activate its kinase activity. Consequently, LKB1 mutants that are deficient for membrane binding fail to activate the downstream target AMPK to control mTOR signalling. Furthermore, the in vivo function of LKB1 during development of Drosophila depends on its capacity to associate with membranes. Strikingly, we find LKB1 to be downregulated in malignant melanoma, which exhibit aberrant activation of Akt and overexpress phosphatidic acid generating Phospholipase D. These results provide evidence for a fundamental mechanism of LKB1 activation and its implication in vivo and during carcinogenesis. LKB1 regulates various cellular processes such as cell proliferation, energy homeostasis and cell polarity and is frequently downregulated in various tumours. Here the authors show that LKB1 activation requires direct binding to phospholipids and show this has an implication for carcinogenesis.
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29
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Cidlinsky N, Dogliotti G, Pukrop T, Jung R, Weber F, Krahn MP. Inactivation of the LKB1-AMPK signaling pathway does not contribute to salivary gland tumor development - a short report. Cell Oncol (Dordr) 2016; 39:389-96. [PMID: 27480082 DOI: 10.1007/s13402-016-0290-8] [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] [Accepted: 07/15/2016] [Indexed: 01/05/2023] Open
Abstract
PURPOSE Activation of AMPK by the tumor suppressor LKB1 represents an essential gatekeeping step for cells under energetic stress to prevent their growth and proliferation by inhibiting mTOR activation, until the energy supply normalizes. The LKB1/AMPK pathway is frequently downregulated in various types of cancer, thereby uncoupling tumor cell growth and proliferation from energy supply. As yet, little information is available on the role of the LKB1/AMPK pathway in tumors derived from salivary gland tissues. METHODS We performed LKB1 protein expression and AMPK and mTOR activation analyses in several salivary gland tumor types and their respective healthy control tissues using immunohistochemistry. RESULTS No significant downregulation of LKB1 expression or decreased activation of AMPK or mTOR were observed in any of the salivary gland tumors tested. In contrast, we found that the salivary gland tumors exhibited an increased rather than a decreased AMPK activation. Although the PI3K/Akt pathway was found to be activated in most of the analyzed tumor samples, the unchanged robust activity of LKB1/AMPK likely prevents (over)activation of mTOR. CONCLUSION In contrast to many other types of cancer, inactivation or downregulation of the LKB1/AMPK pathway does not substantially contribute to the pathogenesis of salivary gland tumors.
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Affiliation(s)
- Natascha Cidlinsky
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Giada Dogliotti
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Tobias Pukrop
- Department of Internal Medicine III, Hematology and Medical Oncology, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053, Regensburg, Germany
| | - Rudolf Jung
- Institute for Pathology, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053, Regensburg, Germany
| | - Florian Weber
- Institute for Pathology, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053, Regensburg, Germany
| | - Michael P Krahn
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany.
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Salminen A, Kauppinen A, Kaarniranta K. AMPK/Snf1 signaling regulates histone acetylation: Impact on gene expression and epigenetic functions. Cell Signal 2016; 28:887-95. [PMID: 27010499 DOI: 10.1016/j.cellsig.2016.03.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 03/18/2016] [Indexed: 01/22/2023]
Abstract
AMP-activated protein kinase (AMPK) and its yeast homolog, Snf1, are critical regulators in the maintenance of energy metabolic balance not only stimulating energy production but also inhibiting energy-consuming processes. The AMPK/Snf1 signaling controls energy metabolism by specific phosphorylation of many metabolic enzymes and transcription factors, enhancing or suppressing their functions. The AMPK/Snf1 complexes can be translocated from cytoplasm into nuclei where they are involved in the regulation of transcription. Recent studies have indicated that AMPK/Snf1 activation can control histone acetylation through different mechanisms affecting not only gene transcription but also many other epigenetic functions. For instance, AMPK/Snf1 enzymes can phosphorylate the histone H3S10 (yeast) and H2BS36 (mammalian) sites which activate specific histone acetyltransferases (HAT), consequently enhancing histone acetylation. Moreover, nuclear AMPK can phosphorylate type 2A histone deacetylases (HDAC), e.g. HDAC4 and HDAC5, triggering their export from nuclei thus promoting histone acetylation reactions. AMPK activation can also increase the level of acetyl CoA, e.g. by inhibiting fatty acid and cholesterol syntheses. Acetyl CoA is a substrate for HATs, thus increasing their capacity for histone acetylation. On the other hand, AMPK can stimulate the activity of nicotinamide phosphoribosyltransferase (NAMPT) which increases the level of NAD(+). NAD(+) is a substrate for nuclear sirtuins, especially for SIRT1 and SIRT6, which deacetylate histones and transcription factors, e.g. those regulating ribosome synthesis and circadian clocks. Histone acetylation is an important epigenetic modification which subsequently can affect chromatin remodeling, e.g. via bromodomain proteins. We will review the signaling mechanisms of AMPK/Snf1 in the control of histone acetylation and subsequently clarify their role in the epigenetic regulation of ribosome synthesis and circadian clocks.
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Affiliation(s)
- Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland.
| | - Anu Kauppinen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland; Department of Ophthalmology, Kuopio University Hospital, Kuopio, Finland
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Shorning BY, Clarke AR. Energy sensing and cancer: LKB1 function and lessons learnt from Peutz-Jeghers syndrome. Semin Cell Dev Biol 2016; 52:21-9. [PMID: 26877140 DOI: 10.1016/j.semcdb.2016.02.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 02/08/2016] [Accepted: 02/08/2016] [Indexed: 12/31/2022]
Abstract
We describe in this review increasing evidence that loss of LKB1 kinase in Peutz-Jeghers syndrome (PJS) derails the existing natural balance between cell survival and tumour growth suppression. LKB1 deletion can plunge cells into an energy/oxidative stress-induced crisis which leads to the activation of alternative and often carcinogenic pathways to maintain cellular energy levels. It therefore appears that although LKB1 deficiency can suppress oncogenic transformation in the short term, it can ultimately lead to more progressed and malignant phenotypes by driving abnormal cell differentiation, genomic instability and increased tumour heterogeneity.
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Affiliation(s)
- Boris Y Shorning
- European Cancer Stem Cell Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, United Kingdom.
| | - Alan R Clarke
- European Cancer Stem Cell Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, United Kingdom
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Nakatsu Y, Iwashita M, Sakoda H, Ono H, Nagata K, Matsunaga Y, Fukushima T, Fujishiro M, Kushiyama A, Kamata H, Takahashi SI, Katagiri H, Honda H, Kiyonari H, Uchida T, Asano T. Prolyl isomerase Pin1 negatively regulates AMP-activated protein kinase (AMPK) by associating with the CBS domain in the γ subunit. J Biol Chem 2015; 290:24255-66. [PMID: 26276391 DOI: 10.1074/jbc.m115.658559] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMPK) plays a critical role in metabolic regulation. In this study, first, it was revealed that Pin1 associates with any isoform of γ, but not with either the α or the β subunit, of AMPK. The association between Pin1 and the AMPK γ1 subunit is mediated by the WW domain of Pin1 and the Thr(211)-Pro-containing motif located in the CBS domain of the γ1 subunit. Importantly, overexpression of Pin1 suppressed AMPK phosphorylation in response to either 2-deoxyglucose or biguanide stimulation, whereas Pin1 knockdown by siRNAs or treatment with Pin1 inhibitors enhanced it. The experiments using recombinant Pin1, AMPK, LKB1, and PP2C proteins revealed that the protective effect of AMP against PP2C-induced AMPKα subunit dephosphorylation was markedly suppressed by the addition of Pin1. In good agreement with the in vitro data, the level of AMPK phosphorylation as well as the expressions of mitochondria-related genes, such as PGC-1α, which are known to be positively regulated by AMPK, were markedly higher with reduced triglyceride accumulation in the muscles of Pin1 KO mice as compared with controls. These findings suggest that Pin1 plays an important role in the pathogenic mechanisms underlying impaired glucose and lipid metabolism, functioning as a negative regulator of AMPK.
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Affiliation(s)
- Yusuke Nakatsu
- From the Department of Medical Science, Graduate School of Medicine
| | - Misaki Iwashita
- the Department of Dental Science for Health Promotion, Graduate School of Biomedical Science, and
| | - Hideyuki Sakoda
- the Department of Internal Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiraku Ono
- the Department of Endocrinology and Diabetes, School of Medicine, Saitama Medical University, Moroyama, Saitama 350-0495, Japan
| | - Kengo Nagata
- From the Department of Medical Science, Graduate School of Medicine
| | - Yasuka Matsunaga
- From the Department of Medical Science, Graduate School of Medicine
| | | | - Midori Fujishiro
- the Department of Internal Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Akifumi Kushiyama
- the Division of Diabetes and Metabolism, Institute for Adult Disease, Asahi Life Foundation, 1-6-1 Marunouchi, Chiyoda-ku, Tokyo 103-0002, Japan
| | - Hideaki Kamata
- From the Department of Medical Science, Graduate School of Medicine
| | - Shin-Ichiro Takahashi
- the Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hideki Katagiri
- the Division of Molecular Metabolism and Diabetes, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan
| | - Hiroaki Honda
- the Department of Disease Model, Research Institute of Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City 734-8553, Hiroshima, Japan
| | - Hiroshi Kiyonari
- the Animal Resource Development Unit and Genetic Engineering Team, Division of Bio-function Dynamics Imaging, RIKEN Center for Life Science Technologies, 2-2-3 Minatojima Minami-machi, Chuou-ku, Kobe 650-0047, Japan, and
| | - Takafumi Uchida
- the Department of Molecular Cell Biology, Graduate School of Agricultural Science, Tohoku University Sendai, Miyagi 981-8555, Japan
| | - Tomoichiro Asano
- From the Department of Medical Science, Graduate School of Medicine,
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Lee SW, Li CF, Jin G, Cai Z, Han F, Chan CH, Yang WL, Li BK, Rezaeian AH, Li HY, Huang HY, Lin HK. Skp2-dependent ubiquitination and activation of LKB1 is essential for cancer cell survival under energy stress. Mol Cell 2015; 57:1022-1033. [PMID: 25728766 DOI: 10.1016/j.molcel.2015.01.015] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 11/24/2014] [Accepted: 01/05/2015] [Indexed: 12/25/2022]
Abstract
LKB1 is activated by forming a heterotrimeric complex with STRAD and MO25. Recent studies suggest that LKB1 has pro-oncogenic functions, besides acting as a tumor suppressor. How the LKB1 activity is maintained and how LKB1 regulates cancer development are largely unclear. Here we show that K63-linked LKB1 polyubiquitination by Skp2-SCF ubiquitin ligase is critical for LKB1 activation by maintaining LKB1-STRAD-MO25 complex integrity. We further demonstrate that oncogenic Ras acts upstream of Skp2 to promote LKB1 polyubiquitination by activating Skp2-SCF ubiquitin ligase. Moreover, Skp2-mediated LKB1 polyubiquitination is required for energy-stress-induced cell survival. We also detected overexpression of Skp2 and LKB1 in late-stage hepatocellular carcinoma (HCC), and their overexpression predicts poor survival outcomes. Finally, we show that Skp2-mediated LKB1 polyubiquitination is important for HCC tumor growth in vivo. Our study provides new insights into the upstream regulation of LKB1 activation and suggests a potential target, the Ras/Skp2/LKB1 axis, for cancer therapy.
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Affiliation(s)
- Szu-Wei Lee
- Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chien-Feng Li
- Department of Pathology, Chi-Mei Foundational Medical Center, Tainan 710, Taiwan; National Institute of Cancer Research, National Health Research Institutes, Tainan 704, Taiwan
| | - Guoxiang Jin
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zhen Cai
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Fei Han
- Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chia-Hsin Chan
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Wei-Lei Yang
- Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Bin-Kui Li
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Abdol Hossein Rezaeian
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hong-Yu Li
- College of Pharmacy, Department of Pharmacology and Toxicology, the University of Arizona, Tucson, AZ 85721, USA
| | - Hsuan-Ying Huang
- Department of Pathology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung City 83301, Taiwan
| | - Hui-Kuan Lin
- Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Graduate Institute of Basic Medical Science, China Medical University, Taichung 404, Taiwan; Department of Biotechnology, Asia University, Taichung 404, Taiwan.
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Cautain B, Hill R, de Pedro N, Link W. Components and regulation of nuclear transport processes. FEBS J 2014; 282:445-62. [PMID: 25429850 PMCID: PMC7163960 DOI: 10.1111/febs.13163] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/11/2014] [Accepted: 11/12/2014] [Indexed: 12/27/2022]
Abstract
The spatial separation of DNA replication and gene transcription in the nucleus and protein translation in the cytoplasm is a uniform principle of eukaryotic cells. This compartmentalization imposes a requirement for a transport network of macromolecules to shuttle these components in and out of the nucleus. This nucleo‐cytoplasmic transport of macromolecules is critical for both cell physiology and pathology. Consequently, investigating its regulation and disease‐associated alterations can reveal novel therapeutic approaches to fight human diseases, such as cancer or viral infection. The characterization of the nuclear pore complex, the identification of transport signals and transport receptors, as well as the characterization of the Ran system (providing the energy source for efficient cargo transport) has greatly facilitated our understanding of the components, mechanisms and regulation of the nucleo‐cytoplasmic transport of proteins in our cells. Here we review this knowledge with a specific emphasis on the selection of disease‐relevant molecular targets for potential therapeutic intervention.
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Affiliation(s)
- Bastien Cautain
- Fundacion MEDINA Parque tecnológico ciencias de la salud, Granada, Spain
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Esteve-Puig R, Gil R, González-Sánchez E, Bech-Serra JJ, Grueso J, Hernández-Losa J, Moliné T, Canals F, Ferrer B, Cortés J, Bastian B, Ramón y Cajal S, Martín-Caballero J, Flores JM, Vivancos A, García-Patos V, Recio JÁ. A mouse model uncovers LKB1 as an UVB-induced DNA damage sensor mediating CDKN1A (p21WAF1/CIP1) degradation. PLoS Genet 2014; 10:e1004721. [PMID: 25329316 PMCID: PMC4199501 DOI: 10.1371/journal.pgen.1004721] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/30/2014] [Indexed: 11/29/2022] Open
Abstract
Exposure to ultraviolet (UV) radiation from sunlight accounts for 90% of the symptoms of premature skin aging and skin cancer. The tumor suppressor serine-threonine kinase LKB1 is mutated in Peutz-Jeghers syndrome and in a spectrum of epithelial cancers whose etiology suggests a cooperation with environmental insults. Here we analyzed the role of LKB1 in a UV-dependent mouse skin cancer model and show that LKB1 haploinsufficiency is enough to impede UVB-induced DNA damage repair, contributing to tumor development driven by aberrant growth factor signaling. We demonstrate that LKB1 and its downstream kinase NUAK1 bind to CDKN1A. In response to UVB irradiation, LKB1 together with NUAK1 phosphorylates CDKN1A regulating the DNA damage response. Upon UVB treatment, LKB1 or NUAK1 deficiency results in CDKN1A accumulation, impaired DNA repair and resistance to apoptosis. Importantly, analysis of human tumor samples suggests that LKB1 mutational status could be a prognostic risk factor for UV-induced skin cancer. Altogether, our results identify LKB1 as a DNA damage sensor protein regulating skin UV-induced DNA damage response. Environmental insults are directly involved in cancer development. In particular, Ultraviolet (UV) radiation has been associated to the acquisition of different types skin cancer and premature skin aging. UV radiation causes modifications in the genetic material of cells (DNA) that if not repaired properly will lead to a mutated DNA (mutated genes) which might trigger the development of cancer. Understanding the molecular basis of the UV-induced DNA damage response is important to elucidate the mechanisms of skin homeostasis and tumorigenesis. Here we provide a UVB-induced skin cancer animal model showing that LKB1 tumor suppressor is also a DNA damage sensor. Importantly, the data suggest that reduced amounts of LKB1 protein in skin could be a risk factor for UV-induced skin carcinogenesis in humans.
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Affiliation(s)
- Rosaura Esteve-Puig
- Animal Models and Cancer Laboratory, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Rosa Gil
- Animal Models and Cancer Laboratory, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Elena González-Sánchez
- Animal Models and Cancer Laboratory, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Joan Josep Bech-Serra
- Proteomic Laboratory Medical Oncology Research Program, Vall d'Hebron Institute of Oncology - VHIO, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Judit Grueso
- Animal Models and Cancer Laboratory, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | | | - Teresa Moliné
- Pathology Department, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Francesc Canals
- Proteomic Laboratory Medical Oncology Research Program, Vall d'Hebron Institute of Oncology - VHIO, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Berta Ferrer
- Pathology Department, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Javier Cortés
- Clinical Oncology Program, Vall d'Hebron Institute of Oncology - VHIO, Barcelona, Spain
| | - Boris Bastian
- Department of Dermatology, University of California San Francisco, San Francisco, California, United States of America
| | | | | | - Juana Maria Flores
- Surgery and Medicine Department, Veterinary School, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana Vivancos
- Cancer Genomics Group Translational Research Program, Vall d'Hebron Institute of Oncology - VHIO, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Vicenç García-Patos
- Dermatology Department, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Juan Ángel Recio
- Animal Models and Cancer Laboratory, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
- * E-mail:
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Liang HJ, Chai RC, Li X, Kong JG, Jiang JH, Ma J, Vatcher G, Yu ACH. Astrocytic exportin-7 responds to ischemia through mediating LKB1 translocation from the nucleus to the cytoplasm. J Neurosci Res 2014; 93:253-67. [PMID: 25250856 DOI: 10.1002/jnr.23486] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 07/16/2014] [Accepted: 08/18/2014] [Indexed: 11/06/2022]
Abstract
The superfamily of importin-β-related proteins is the largest class of nuclear transport receptors and can be generally divided into importins and exportins according to their transport directions. Eleven importins and seven exportins have been identified, and the expression patterns of both classes are important for their functions in nucleocytoplasmic transport activities. This study demonstrates that all of the importins (importin-β; transportin-1, -2, and -3; and importin-4, -5, -7, -8, -9, -11, and -13) and all the exportins (exportin-1, -2, -4, -5, -6, -7, and -t) are differentially expressed in the cerebral cortex, cerebellum, hippocampus, and brainstem and in primary cultures of cerebral cortical astrocytes and neurons. For astrocytes, we observed that different importins and exportins displayed different expression changes during 0-6 hr of ischemia treatment, especially an increase of both the mRNA and the protein of exportin-7. Immunostaining showed that exportin-7 accumulated inside the nucleus and around the nuclear envelope. In addition, we noticed an increased cytoplasmic distribution of one of the cargo proteins of exportin-7, LKB1, an important element in maintaining energy homeostasis. This increased cytoplasmic distribution was accompanied by an increased expression of exportin-7 under ischemia in astrocytes. We demonstrate that exportin-7 responds to ischemia in astrocytes and that this response involves translocation of LKB1, a protein that plays important roles during metabolic stress, from the nucleus to the cytoplasm.
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Affiliation(s)
- Hai Jie Liang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, China; Key Laboratory for Neuroscience of the Ministry of Education and Key Laboratory for Neuroscience of the National Health and Family Planning Commission, Peking University, Beijing, China
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Abstract
LKB1 is commonly thought of as a tumor suppressor gene because its hereditary mutation is responsible for a cancer syndrome, and somatic inactivation of LKB1 is found in non-small cell lung cancer, melanoma, and cervical cancers. However, unlike other tumor suppressors whose main function is to either suppress cell proliferation or promote cell death, one of the functions of LKB1-regulated AMPK signaling is to suppress cell proliferation in order to promote cell survival under energetic stress conditions. This unique, pro-survival function of LKB1 has led to the discovery of reagents, such as phenformin, that specifically exploit the vulnerability of LKB1-null cells in their defect in sensing energetic stress. Such targeted agents represent a novel treatment strategy because they induce cell killing when LKB1 is absent. This review article summarizes various vulnerabilities of LKB1-mutant cells that have been reported in the literature and discusses the potential of using existing or developing novel reagents to target cancer cells with defective LKB1.
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Affiliation(s)
- Wei Zhou
- Corresponding author. Departments of Hematology and Medical Oncology, Emory University School of Medicine, 1365 Clifton Road, NE, Suite C4084, Atlanta 30322, Georgia. Tel.: +995 404 778 2134; fax: +995 404 778 5530.
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Bang S, Chen Y, Ahima RS, Kim SF. Convergence of IPMK and LKB1-AMPK signaling pathways on metformin action. Mol Endocrinol 2014; 28:1186-93. [PMID: 24877601 DOI: 10.1210/me.2014-1134] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Metformin is a biguanide drug that is widely prescribed for type 2 diabetes. Metformin suppresses hepatic gluconeogenesis and increases fatty acid oxidation. Although studies have suggested that metformin acts, at least in part, via activation of the liver kinase B1 (LKB1)/AMP-activated protein kinase (AMPK) pathway, the specific molecular mechanisms underlying metformin's regulation of glucose and lipid metabolism have not been well delineated. Recently, we have shown that inositol polyphosphate multikinase (IPMK) plays an important role in cellular energy metabolism and glucose-mediated AMPK regulation. Here we investigated the role of IPMK in metformin-induced AMPK activation. We observed that metformin-mediated activation of AMPK was impaired in the absence of IPMK. Overexpression of wild-type IPMK was sufficient to restore LKB1-AMPK activation by either metformin or AICAR in IPMK(-/-) murine embryonic fibroblast cells, suggesting that IPMK may act as an upstream regulator of LKB1-AMPK signaling in response to metformin. Moreover, this regulation was mediated by protein-protein interaction between IPMK and LKB1 as a dominant-negative peptide, which abrogates this interaction, attenuated metformin's ability to activate AMPK. Our data demonstrate that IPMK plays an important role in LKB1/AMPK signaling and may be targeted for treatment of metabolic diseases.
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Affiliation(s)
- Sookhee Bang
- Department of Psychiatry and Pharmacology, Center for Neurobiology and Behavior (S.B., Y.C., S.F.K.); and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism and the Institute for Diabetes, Obesity, and Metabolism (R.S.A.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Cáceres-Gorriti KY, Carmona E, Barrès V, Rahimi K, Létourneau IJ, Tonin PN, Provencher D, Mes-Masson AM. RAN nucleo-cytoplasmic transport and mitotic spindle assembly partners XPO7 and TPX2 are new prognostic biomarkers in serous epithelial ovarian cancer. PLoS One 2014; 9:e91000. [PMID: 24625450 PMCID: PMC3953127 DOI: 10.1371/journal.pone.0091000] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 02/06/2014] [Indexed: 01/25/2023] Open
Abstract
Purpose Epithelial ovarian cancer has the highest mortality rate of all gynecological malignancies. We have shown that high RAN expression strongly correlates with high-grade and poor patient survival in epithelial ovarian cancer. However, as RAN is a small GTPase involved in two main biological functions, nucleo-cytoplasmic transport and mitosis, it is still unknown which of these functions associate with poor prognosis. Methods To examine the biomarker value of RAN network components in serous epithelial ovarian cancer, protein expression of six specific RAN partners was analyzed by immunohistochemistry using a tissue microarray representing 143 patients associated with clinical parameters. The RAN GDP/GTP cycle was evaluated by the expression of RANBP1 and RCC1, the mitotic function by TPX2 and IMPβ, and the nucleo-cytoplasmic trafficking function by XPO7, XPOT and IMPβ. Results Based on Kaplan-Meier analyses, RAN, cytoplasmic XPO7 and TPX2 were significantly associated with poor overall patient survival, and RAN and TPX2 were associated with lower disease free survival in patients with high-grade serous carcinoma. Cox regression analysis revealed that RAN and TPX2 expression were independent prognostic factors for both overall and disease free survival, and that cytoplasmic XPO7 expression was a prognostic factor for overall patient survival. Conclusions In this systematic study, we show that RAN and two protein partners involved in its nucleo-cytoplasmic and mitotic functions (XPO7 and TPX2, respectively) can be used as biomarkers to stratify patients based on prognosis. In particular, we reported for the first time the clinical relevance of the exportin XPO7 and showed that TPX2 expression had the strongest prognostic value. These findings suggest that protein partners in each of RAN’s functions can discriminate between different outcomes in high-grade serous epithelial ovarian cancer patients. Furthermore, these proteins point to cellular processes that may ultimately be targeted to improve the survival in serous epithelial ovarian cancer.
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Affiliation(s)
- Katia Y. Cáceres-Gorriti
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Canada
- Institut du Cancer de Montréal, Montreal, Canada
| | - Euridice Carmona
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Canada
- Institut du Cancer de Montréal, Montreal, Canada
| | - Véronique Barrès
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Canada
- Institut du Cancer de Montréal, Montreal, Canada
| | - Kurosh Rahimi
- Department of Pathology, Centre Hospitalier de l’Université de Montréal (CHUM), Montreal, Canada
| | - Isabelle J. Létourneau
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Canada
- Institut du Cancer de Montréal, Montreal, Canada
| | - Patricia N. Tonin
- The Research Institute of the McGill University Health Centre, Montreal, Canada
- Department of Human Genetics, McGill University, Montreal, Canada
- Department of Medicine, McGill University, Montreal, Canada
| | - Diane Provencher
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Canada
- Institut du Cancer de Montréal, Montreal, Canada
- Department of Obstetric-Gynecology, Université de Montréal, Montreal, Canada
- Department of Medicine, Université de Montréal, Montreal, Canada
| | - Anne-Marie Mes-Masson
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Montreal, Canada
- Institut du Cancer de Montréal, Montreal, Canada
- Department of Medicine, Université de Montréal, Montreal, Canada
- * E-mail:
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Veleva-Rotse BO, Smart JL, Baas AF, Edmonds B, Zhao ZM, Brown A, Klug LR, Hansen K, Reilly G, Gardner AP, Subbiah K, Gaucher EA, Clevers H, Barnes AP. STRAD pseudokinases regulate axogenesis and LKB1 stability. Neural Dev 2014; 9:5. [PMID: 24594058 PMCID: PMC4016016 DOI: 10.1186/1749-8104-9-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 02/18/2014] [Indexed: 11/12/2022] Open
Abstract
Background Neuronal polarization is an essential step of morphogenesis and connectivity in the developing brain. The serine/threonine kinase LKB1 is a key regulator of cell polarity, metabolism, tumorigenesis, and is required for axon formation. It is allosterically regulated by two related and evolutionarily conserved pseudokinases, STe20-Related ADapters (STRADs) α and β. The roles of STRADα and STRADβ in the developing nervous system are not fully defined, nor is it known whether they serve distinct functions. Results We find that STRADα is highly spliced and appears to be the primal STRAD paralog. We report that each STRAD is sufficient for axogenesis and promoting cell survival in the developing cortex. We also reveal a reciprocal protein-stabilizing relationship in vivo between LKB1 and STRADα, whereby STRADα specifically maintains LKB1 protein levels via cytoplasmic compartmentalization. Conclusions We demonstrate a novel role for STRADβ in axogenesis and also show for the first time in vivo that STRADα, but not STRADβ, is responsible for LKB1 protein stability.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Anthony P Barnes
- Department of Pediatrics-Doernbecher, Children's Hospital, Portland, OR 97239, USA.
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Bouchekioua-Bouzaghou K, Poulard C, Rambaud J, Lavergne E, Hussein N, Billaud M, Bachelot T, Chabaud S, Mader S, Dayan G, Treilleux I, Corbo L, Le Romancer M. LKB1 when associated with methylatedERα is a marker of bad prognosis in breast cancer. Int J Cancer 2014; 135:1307-18. [PMID: 24615515 DOI: 10.1002/ijc.28781] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 01/20/2014] [Accepted: 01/28/2014] [Indexed: 01/09/2023]
Abstract
Although the presence of nuclear estrogen receptor is widely used to guide breast cancer therapy, less attention has been paid to the receptor cytoplasmic signaling. Recently, we have shown that this pathway is operative in vivo and is activated in aggressive tumors representing a new potential target for breast cancer therapy. Here, we identified LKB1 as a partner of ERα and we explored its potential role in estrogen nongenomic signaling. The associations between LKB1 expression and the actors of this pathway, namely the methylated form of ERα (metERα), Src and PI3K, have been analyzed both in cultured cells and in 154 primary breast tumor samples. We found that LKB1 is a component of the cytoplasmic signaling complex in breast cell lines as well as in primary breast tumors. Moreover, an inverse correlation between the localization of LKB1 in nuclear and cytoplasmic compartments is observed. Importantly, high expression of cytoplasmic LKB1 is an independent marker of poor prognosis, associated with reduced overall survival (OS) and disease free survival (DFS). Conversely, the presence of nuclear LKB1 associates with increased OS and DFS. In conclusion, our results highlight that LKB1 expression in breast cancer appears to have opposite effects depending on its subcellular localization and may be used as a new prognostic biomarker.
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Affiliation(s)
- Katia Bouchekioua-Bouzaghou
- Université de Lyon, France; Université Lyon 1, France; Inserm U1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; Equipe Labellisée "La Ligue", Lyon, France
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Sangel P, Oka M, Yoneda Y. The role of Importin-βs in the maintenance and lineage commitment of mouse embryonic stem cells. FEBS Open Bio 2014; 4:112-20. [PMID: 24490135 PMCID: PMC3907685 DOI: 10.1016/j.fob.2014.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 11/29/2013] [Accepted: 01/02/2014] [Indexed: 01/08/2023] Open
Abstract
Members of the Importin-β family recognize nuclear localization signals (NLS) and nuclear export signals (NES). These proteins play important roles in various nucleocytoplasmic transport processes in cells. Here, we examined the expression patterns of 21 identified Importin-β genes in mouse embryonic stem cells (mESCs), mouse embryonic fibroblast (MEF) and mESCs differentiated into neural ectoderm (NE) or mesoendoderm (ME). We observed striking differences in the Importin-β mRNA expression levels within these cell types. We also found that knockdown of selected Importin-β genes led to suppression of Nanog, and altered the balance of Oct4/Sox2 expression ratio, which is important for NE/ME lineage choice. Furthermore, we demonstrated that knockdown of XPO4, RanBP17, RanBP16, or IPO7 differentially affected the lineage selection of differentiating mESCs. More specifically, knockdown of XPO4 selectively stimulated the mESC differentiation towards definitive endoderm, while concomitantly inhibiting NE differentiation. RanBP17 knockdown also promoted endodermal differentiation with no effect on NE differentiation. RanBP16 knockdown caused differentiation into ME, while IPO7 knockdown inhibited NE differentiation, without obvious effects on the other lineages. Collectively, our results suggest that Importin-βs play important roles in cell fate determination processes of mESCs, such as in the maintenance of pluripotency or selection of lineage during differentiation. Importin-β expression patterns are distinct in mESCs, MEFs, NE and ME cells. Importin-β may modulate differentiation and lineage selection in mESCs. Suppression of either XPO4 or RanBP17 induces endodermal differentiation in mESCs. RanBP16 suppression induces a ME differentiation in mESCs. XPO4 and IPO7 are essential for mESC differentiation into NE cells.
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Affiliation(s)
- Percival Sangel
- Biomolecular Dynamics Laboratory, Department of Frontier Bioscience, Graduate School of Frontier Bioscience, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Masahiro Oka
- Biomolecular Dynamics Laboratory, Department of Frontier Bioscience, Graduate School of Frontier Bioscience, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan ; Department of Biochemistry, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan ; JST, CREST, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yoshihiro Yoneda
- Biomolecular Dynamics Laboratory, Department of Frontier Bioscience, Graduate School of Frontier Bioscience, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan ; Department of Biochemistry, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan ; JST, CREST, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan
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Partanen JI, Tervonen TA, Klefström J. Breaking the epithelial polarity barrier in cancer: the strange case of LKB1/PAR-4. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130111. [PMID: 24062587 DOI: 10.1098/rstb.2013.0111] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The PAR clan of polarity regulating genes was initially discovered in a genetic screen searching for genes involved in asymmetric cell divisions in the Caenorhabditis elegans embryo. Today, investigations in worms, flies and mammals have established PAR proteins as conserved and fundamental regulators of animal cell polarization in a broad range of biological phenomena requiring cellular asymmetries. The human homologue of invertebrate PAR-4, a serine-threonine kinase LKB1/STK11, has caught attention as a gene behind Peutz-Jeghers polyposis syndrome and as a bona fide tumour suppressor gene commonly mutated in sporadic cancer. LKB1 functions as a master regulator of AMP-activated protein kinase (AMPK) and 12 other kinases referred to as the AMPK-related kinases, including four human homologues of PAR-1. The role of LKB1 as part of the energy sensing LKB1-AMPK module has been intensively studied, whereas the polarity function of LKB1, in the context of homoeostasis or cancer, has gained less attention. Here, we focus on the PAR-4 identity of LKB1, discussing the weight of evidence indicating a role for LKB1 in regulation of cell polarity and epithelial integrity across species and highlight recent investigations providing new insight into the old question: does the PAR-4 identity of LKB1 matter in cancer?
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Affiliation(s)
- Johanna I Partanen
- Cancer Cell Circuitry Laboratory, Translational Cancer Biology Research Program and Institute of Biomedicine, University of Helsinki, , Biomedicum Helsinki, Rm B507b, PO Box 63, Haartmaninkatu 8, 00014 Helsinki, Finland
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Liang P, Zhang H, Wang G, Li S, Cong S, Luo Y, Zhang B. KPNB1, XPO7 and IPO8 mediate the translocation ofNF-κB/p65 into the nucleus. Traffic 2013; 14:1132-43. [PMID: 23906023 DOI: 10.1111/tra.12097] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 07/30/2013] [Accepted: 08/01/2013] [Indexed: 12/25/2022]
Abstract
NF-κB/p65 is retained in the cytoplasm until it is activated in response to stress. Nuclear import of p65 is regulated by importin α in a nuclear localization signal (NLS)-dependent manner. However, the role of importin β family members in the nuclear translocation of p65 is largely unclear. In this study, using high-content siRNA screening, we identified three of 17 importin β family members that are involved in the nuclear import of p65. Our data showed that knockdown of KPNB1, XPO7 and IPO8 reduced the amount of nuclear p65 following tumor necrosis factor-α (TNF-α) stimulation, resulting in lower NF-κB activity. KPNB1 was the major importin β receptor for p65 import, and this import was dependent on the NLS of p65. However, NLS-mutated p65 still entered the nucleus and bound to XPO7 and IPO8. Interestingly, among the six members of the importin α family, KPNA2 was most important for p65 import. Taken together, our results show that the import of p65 mainly relies on the canonical KPNA2/KPNB1 pathway; however, p65 is also imported by an alternative pathway that is independent of its NLS. Redundant importin receptors are likely to maintain the important function of p65 according to need.
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Affiliation(s)
- Peizhou Liang
- State Key Laboratory of Respiratory Diseases, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Guangzhou , 510530, China
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Zhu H, Moriasi CM, Zhang M, Zhao Y, Zou MH. Phosphorylation of serine 399 in LKB1 protein short form by protein kinase Cζ is required for its nucleocytoplasmic transport and consequent AMP-activated protein kinase (AMPK) activation. J Biol Chem 2013; 288:16495-16505. [PMID: 23612973 PMCID: PMC3675585 DOI: 10.1074/jbc.m112.443580] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 04/21/2013] [Indexed: 11/06/2022] Open
Abstract
Two splice variants of LKB1 exist: LKB1 long form (LKB1(L)) and LKB1 short form (LKB1(S)). In a previous study, we demonstrated that phosphorylation of Ser-428/431 (in LKB1(L)) by protein kinase Cζ (PKCζ) was essential for LKB1-mediated activation of AMP-activated protein kinase (AMPK) in response to oxidants or metformin. Paradoxically, LKB1S also activates AMPK although it lacks Ser-428/431. Thus, we hypothesized that LKB1(S) contained additional phosphorylation sites important in AMPK activation. Truncation analysis and site-directed mutagenesis were used to identify putative PKCζ phosphorylation sites in LKB1(S). Substitution of Ser-399 to alanine did not alter the activity of LKB1(S), but abolished peroxynitrite- and metformin-induced activation of AMPK. Furthermore, the phosphomimetic mutation (S399D) increased the phosphorylation of AMPK and its downstream target phospho-acetyl-coenzyme A carboxylase (ACC). PKCζ-dependent phosphorylation of Ser-399 triggered nucleocytoplasmic translocation of LKB1(S) in response to metformin or peroxynitrite treatment. This effect was ablated by pharmacological and genetic inhibition of PKCζ, by inhibition of CRM1 activity and by substituting Ser-399 with alanine (S399A). Overexpression of PKCζ up-regulated metformin-mediated phosphorylation of both AMPK (Thr-172) and ACC (Ser-79), but the effect was ablated in the S399A mutant. We conclude that, similar to Ser-428/431 (in LKB1(L)), Ser-399 (in LKB1(S)) is a PKCζ-dependent phosphorylation site essential for nucleocytoplasmic export of LKB1(S) and consequent AMPK activation.
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Affiliation(s)
- Huaiping Zhu
- Section of Molecular Medicine, Department of Medicine, Oklahoma City, Oklahoma 73013
| | - Cate M Moriasi
- Section of Molecular Medicine, Department of Medicine, Oklahoma City, Oklahoma 73013
| | - Miao Zhang
- Section of Molecular Medicine, Department of Medicine, Oklahoma City, Oklahoma 73013
| | - Yu Zhao
- Section of Molecular Medicine, Department of Medicine, Oklahoma City, Oklahoma 73013
| | - Ming-Hui Zou
- Section of Molecular Medicine, Department of Medicine, Oklahoma City, Oklahoma 73013; Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73013.
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Caenorhabditis elegans PIG-1/MELK acts in a conserved PAR-4/LKB1 polarity pathway to promote asymmetric neuroblast divisions. Genetics 2012; 193:897-909. [PMID: 23267054 DOI: 10.1534/genetics.112.148106] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Asymmetric cell divisions produce daughter cells with distinct sizes and fates, a process important for generating cell diversity during development. Many Caenorhabditis elegans neuroblasts, including the posterior daughter of the Q cell (Q.p), divide to produce a larger neuron or neuronal precursor and a smaller cell that dies. These size and fate asymmetries require the gene pig-1, which encodes a protein orthologous to vertebrate MELK and belongs to the AMPK-related family of kinases. Members of this family can be phosphorylated and activated by the tumor suppressor kinase LKB1, a conserved polarity regulator of epithelial cells and neurons. In this study, we present evidence that the C. elegans orthologs of LKB1 (PAR-4) and its partners STRAD (STRD-1) and MO25 (MOP-25.2) regulate the asymmetry of the Q.p neuroblast division. We show that PAR-4 and STRD-1 act in the Q lineage and function genetically in the same pathway as PIG-1. A conserved threonine residue (T169) in the PIG-1 activation loop is essential for PIG-1 activity, consistent with the model that PAR-4 (or another PAR-4-regulated kinase) phosphorylates and activates PIG-1. We also demonstrate that PIG-1 localizes to centrosomes during cell divisions of the Q lineage, but this localization does not depend on T169 or PAR-4. We propose that a PAR-4-STRD-1 complex stimulates PIG-1 kinase activity to promote asymmetric neuroblast divisions and the generation of daughter cells with distinct fates. Changes in cell fate may underlie many of the abnormal behaviors exhibited by cells after loss of PAR-4 or LKB1.
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Calamaras TD, Lee C, Lan F, Ido Y, Siwik DA, Colucci WS. Post-translational modification of serine/threonine kinase LKB1 via Adduction of the Reactive Lipid Species 4-Hydroxy-trans-2-nonenal (HNE) at lysine residue 97 directly inhibits kinase activity. J Biol Chem 2012; 287:42400-6. [PMID: 23086944 PMCID: PMC3516783 DOI: 10.1074/jbc.m112.385831] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 10/18/2012] [Indexed: 02/03/2023] Open
Abstract
Oxidative stress is pathogenic in a variety of diseases, but the mechanism by which cellular signaling is affected by oxidative species has yet to be fully characterized. Lipid peroxidation, a secondary process that occurs during instances of free radical production, may play an important role in modulating cellular signaling under conditions of oxidative stress. 4-Hydroxy-trans-2-nonenal (HNE) is an electrophilic aldehyde produced during lipid peroxidation that forms covalent adducts on proteins, altering their activity and function. One such target, LKB1, has been reported to be inhibited by HNE adduction. We tested the hypothesis that HNE inhibits LKB1 activity through adduct formation on a specific reactive residue of the protein. To elucidate the mechanism of the inhibitory effect, HEK293T cells expressing LKB1 were treated with HNE (10 μm for 1 h) and assayed for HNE-LKB1 adduct formation and changes in LKB1 kinase activity. HNE treatment resulted in the formation of HNE-LKB1 adducts and decreased LKB1 kinase activity by 31 ± 9% (S.E.) but had no effect on the association of LKB1 with its adaptor proteins sterile-20-related adaptor and mouse protein 25. Mutation of LKB1 lysine residue 97 reduced HNE adduct formation and attenuated the effect of HNE on LKB1 activity. Taken together, our results suggest that adduction of LKB1 Lys-97 mediates the inhibitory effect of HNE.
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Affiliation(s)
- Timothy D. Calamaras
- From the Myocardial Biology Unit, Cardiovascular Medicine, Department of Medicine and
| | - Charlie Lee
- From the Myocardial Biology Unit, Cardiovascular Medicine, Department of Medicine and
| | - Fan Lan
- Diabetes and Metabolism Research Unit, Section of Endocrinology, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Yasuo Ido
- Diabetes and Metabolism Research Unit, Section of Endocrinology, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Deborah A. Siwik
- From the Myocardial Biology Unit, Cardiovascular Medicine, Department of Medicine and
| | - Wilson S. Colucci
- From the Myocardial Biology Unit, Cardiovascular Medicine, Department of Medicine and
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Lohia M, Qin Y, Macara IG. The Scribble polarity protein stabilizes E-cadherin/p120-catenin binding and blocks retrieval of E-cadherin to the Golgi. PLoS One 2012; 7:e51130. [PMID: 23226478 PMCID: PMC3511384 DOI: 10.1371/journal.pone.0051130] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 10/31/2012] [Indexed: 11/18/2022] Open
Abstract
Several polarity proteins, including Scribble (Scrb) have been implicated in control of vesicle traffic, and in particular the endocytosis of E-cadherin, but through unknown mechanisms. We now show that depletion of Scrb enhances endocytosis of E-cadherin by weakening the E-cadherin-p120catenin interaction. Unexpectedly, however, the internalized E-cadherin is not degraded but accumulates in the Golgi apparatus. Silencing p120-catenin causes degradation of E-cadherin in lysosomes, but degradation is blocked by the co-depletion of Scrb, which diverts the internalized E-cadherin to the Golgi. Loss of Scrb also enhances E-cadherin binding to retromer components, and retromer is required for Golgi accumulation of Scrb, and E-cadherin stability. These data identify a novel and unanticipated function for Scrb in blocking retromer-mediated diversion of E-cadherin to the Golgi. They provide evidence that polarity proteins can modify the intracellular itinerary for endocytosed membrane proteins.
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Affiliation(s)
- Madhura Lohia
- Department of Microbiology, Ctr for Cell Signaling, University of Virginia School of Medicine Charlottesville, Virginia, United States of America
| | - Yi Qin
- Department of Microbiology, Ctr for Cell Signaling, University of Virginia School of Medicine Charlottesville, Virginia, United States of America
| | - Ian G. Macara
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, United States of America
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Nakagawa K, Uehata Y, Natsuizaka M, Kohara T, Darmanin S, Asaka M, Takeda H, Kobayashi M. The nuclear protein Artemis promotes AMPK activation by stabilizing the LKB1-AMPK complex. Biochem Biophys Res Commun 2012; 427:790-5. [PMID: 23044421 DOI: 10.1016/j.bbrc.2012.09.140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 09/23/2012] [Indexed: 01/03/2023]
Abstract
AMP-activated protein kinase (AMPK) is a hetero-trimeric Ser/Thr kinase composed of a catalytic α subunit and regulatory β and γ subunits; it functions as an energy sensor that controls cellular energy homeostasis. In response to an increased cellular AMP/ATP ratio, AMPK is activated by phosphorylation at Thr172 in the α-subunit by upstream AMPK kinases (AMPKKs), including tumor suppressor liver kinase B1 (LKB1). To elucidate more precise molecular mechanisms of AMPK activation, we performed yeast two-hybrid screening and isolated the complementary DNA (cDNA) encoding the nuclear protein Artemis/DNA cross-link repair 1C (DCLRE1C) as an AMPKα2-binding protein. Artemis was found to co-immunoprecipitate with AMPKα2, and the co-localization of Artemis with AMPKα2 in the nucleus was confirmed by immunofluorescence staining in U2OS cells. Moreover, over-expression of Artemis enhanced the phosphorylation of AMPKα2 and the AMPK substrate acetyl-CoA carboxylase (ACC). Conversely, RNAi-mediated knockdown of Artemis reduced AMPK and ACC phosphorylation. In addition, Artemis markedly increased the physical association between AMPKα2 and LKB1. Taken together, these results suggest that Artemis functions as a positive regulator of AMPK signaling by stabilizing the LKB1-AMPK complex.
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Affiliation(s)
- Koji Nakagawa
- Department of Pathophysiology and Therapeutics, Division of Pharmascience, Faculty of Pharmaceutical Sciences, Hokkaido University, N12 W6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan.
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50
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Ma L, Niknejad N, Gorn-Hondermann I, Dayekh K, Dimitroulakos J. Lovastatin induces multiple stress pathways including LKB1/AMPK activation that regulate its cytotoxic effects in squamous cell carcinoma cells. PLoS One 2012; 7:e46055. [PMID: 23029387 PMCID: PMC3460930 DOI: 10.1371/journal.pone.0046055] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 08/27/2012] [Indexed: 01/09/2023] Open
Abstract
Background Cellular stress responses trigger signaling cascades that inhibit proliferation and protein translation to help alleviate the stress or if the stress cannot be overcome induce apoptosis. In recent studies, we demonstrated the ability of lovastatin, an inhibitor of mevalonate synthesis, to induce the Integrated Stress Response as well as inhibiting epidermal growth factor receptor (EGFR) activation. Methodology/Principal Findings In this study, we evaluated the effects of lovastatin on the activity of the LKB1/AMPK pathway that is activated upon cellular energy shortage and can interact with the above pathways. In the squamous cell carcinoma (SCC) cell lines SCC9 and SCC25, lovastatin treatment (1–25 µM, 24 hrs) induced LKB1 and AMPK activation similar to metformin (1–10 mM, 24 hrs), a known inducer of this pathway. Lovastatin treatment impaired mitochondrial function and also decreased cellular ADP/ATP ratios, common triggers of LKB1/AMPK activation. The cytotoxic effects of lovastatin were attenuated in LKB1 null MEFs indicating a role for this pathway in regulating lovastatin-induced cytotoxicity. Of clinical relevance, lovastatin induces synergistic cytotoxicity in combination with the EGFR inhibitor gefitinib. In LKB1 deficient (A549, HeLa) and expressing (SCC9, SCC25) cell lines, metformin enhanced gefitinib cytotoxicity only in LKB1 expressing cell lines while both groups showed synergistic cytotoxic effects with lovastatin treatments. Furthermore, the combination of lovastatin with gefitinib induced a potent apoptotic response without significant induction of autophagy that is often induced during metabolic stress inhibiting cell death. Conclusion/Significance Thus, targeting multiple metabolic stress pathways including the LKB1/AMPK pathway enhances lovastatin’s ability to synergize with gefitinib in SCC cells.
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Affiliation(s)
- Laurie Ma
- Centre for Cancer Therapeutics, The Ottawa Hospital Research Institute, Ontario, Canada
| | - Nima Niknejad
- Centre for Cancer Therapeutics, The Ottawa Hospital Research Institute, Ontario, Canada
| | - Ivan Gorn-Hondermann
- Centre for Cancer Therapeutics, The Ottawa Hospital Research Institute, Ontario, Canada
| | - Khalil Dayekh
- Centre for Cancer Therapeutics, The Ottawa Hospital Research Institute, Ontario, Canada
- The Faculty of Medicine and the Department of Biochemistry, University of Ottawa, Ontario, Canada
| | - Jim Dimitroulakos
- Centre for Cancer Therapeutics, The Ottawa Hospital Research Institute, Ontario, Canada
- The Faculty of Medicine and the Department of Biochemistry, University of Ottawa, Ontario, Canada
- * E-mail:
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