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Senthivinayagam S, Serbulea V, Upchurch CM, Polanowska-Grabowska R, Mendu SK, Sahu S, Jayaguru P, Aylor KW, Chordia MD, Steinberg L, Oberholtzer N, Uchiyama S, Inada N, Lorenz UM, Harris TE, Keller SR, Meher AK, Kadl A, Desai BN, Kundu BK, Leitinger N. Adaptive thermogenesis in brown adipose tissue involves activation of pannexin-1 channels. Mol Metab 2021; 44:101130. [PMID: 33248294 PMCID: PMC7779784 DOI: 10.1016/j.molmet.2020.101130] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 11/06/2020] [Accepted: 11/21/2020] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Brown adipose tissue (BAT) is specialized in thermogenesis. The conversion of energy into heat in brown adipocytes proceeds via stimulation of β-adrenergic receptor (βAR)-dependent signaling and activation of mitochondrial uncoupling protein 1 (UCP1). We have previously demonstrated a functional role for pannexin-1 (Panx1) channels in white adipose tissue; however, it is not known whether Panx1 channels play a role in the regulation of brown adipocyte function. Here, we tested the hypothesis that Panx1 channels are involved in brown adipocyte activation and thermogenesis. METHODS In an immortalized brown pre-adipocytes cell line, Panx1 currents were measured using patch-clamp electrophysiology. Flow cytometry was used for assessment of dye uptake and luminescence assays for adenosine triphosphate (ATP) release, and cellular temperature measurement was performed using a ratiometric fluorescence thermometer. We used RNA interference and expression plasmids to manipulate expression of wild-type and mutant Panx1. We used previously described adipocyte-specific Panx1 knockout mice (Panx1Adip-/-) and generated brown adipocyte-specific Panx1 knockout mice (Panx1BAT-/-) to study pharmacological or cold-induced thermogenesis. Glucose uptake into brown adipose tissue was quantified by positron emission tomography (PET) analysis of 18F-fluorodeoxyglucose (18F-FDG) content. BAT temperature was measured using an implantable telemetric temperature probe. RESULTS In brown adipocytes, Panx1 channel activity was induced either by apoptosis-dependent caspase activation or by β3AR stimulation via a novel mechanism that involves Gβγ subunit binding to Panx1. Inactivation of Panx1 channels in cultured brown adipocytes resulted in inhibition of β3AR-induced lipolysis, UCP-1 expression, and cellular thermogenesis. In mice, adiponectin-Cre-dependent genetic deletion of Panx1 in all adipose tissue depots resulted in defective β3AR agonist- or cold-induced thermogenesis in BAT and suppressed beigeing of white adipose tissue. UCP1-Cre-dependent Panx1 deletion specifically in brown adipocytes reduced the capacity for adaptive thermogenesis without affecting beigeing of white adipose tissue and aggravated diet-induced obesity and insulin resistance. CONCLUSIONS These data demonstrate that Gβγ-dependent Panx1 channel activation is involved in β3AR-induced thermogenic regulation in brown adipocytes. Identification of Panx1 channels in BAT as novel thermo-regulatory elements downstream of β3AR activation may have therapeutic implications.
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Affiliation(s)
| | - Vlad Serbulea
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Clint M Upchurch
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | | | - Suresh K Mendu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Srabani Sahu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Prathiba Jayaguru
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Virginia, Charlottesville, VA, 22908, USA
| | - Kevin W Aylor
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia, Charlottesville, VA, 22908, USA
| | - Mahendra D Chordia
- Department of Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Limor Steinberg
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Nathaniel Oberholtzer
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Seichii Uchiyama
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Noriko Inada
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan
| | - Ulrike M Lorenz
- Department of Microbiology, Immunology and Cancer Biology, Center for Cell Clearance, the Beirne B. Carter Center for Immunology Research, USA
| | - Thurl E Harris
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Susanna R Keller
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia, Charlottesville, VA, 22908, USA
| | - Akshaya K Meher
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Alexandra Kadl
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Virginia, Charlottesville, VA, 22908, USA
| | - Bimal N Desai
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Bijoy K Kundu
- Department of Radiology and Medical Imaging, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA; Department of Biomedical Engineering, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Norbert Leitinger
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA; Robert M Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, 22908, USA.
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Najt CP, Senthivinayagam S, Aljazi MB, Fader KA, Olenic SD, Brock JRL, Lydic TA, Jones AD, Atshaves BP. Liver-specific loss of Perilipin 2 alleviates diet-induced hepatic steatosis, inflammation, and fibrosis. Am J Physiol Gastrointest Liver Physiol 2016; 310:G726-38. [PMID: 26968211 PMCID: PMC4867327 DOI: 10.1152/ajpgi.00436.2015] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 03/08/2016] [Indexed: 01/31/2023]
Abstract
Hepatic inflammation and fibrosis are key elements in the pathogenesis of nonalcoholic steatohepatitis (NASH), a progressive liver disease initiated by excess hepatic lipid accumulation. Lipid droplet protein Perilipin 2 (Plin2) alleviates dietary-induced hepatic steatosis when globally ablated; however, its role in the progression of NASH remains unknown. To investigate this further, we challenged Plin2 liver-specific knockout mice (designated L-KO) and their respective wild-type (WT) controls with a methionine-choline-deficient (MCD) diet for 15 days to induce a NASH phenotype of increased hepatic triglyceride levels through impaired phosphatidylcholine (PC) synthesis and very-low-density lipoprotein (VLDL) secretion. Results on liver weights, body weights, fat tissue mass, and histology in WT and L-KO mice fed the MCD diet revealed signs of hepatic steatosis, fibrosis, and inflammation; however, these effects were blunted in L-KO mice. In addition, levels of PC and VLDL were unchanged, and hepatic steatosis was reduced in L-KO mice fed the MCD diet, due in part to an increase in remodeling of PE to PC via the enzyme phosphatidylethanolamine N-methyltransferase (PEMT). These mice also exhibited decreased hepatic expression of proinflammatory markers cyclooxygenase 2, IL-6, TNF-α, IL-1β, and reduced expression of endoplasmic reticulum (ER) stress proteins C/EBP homologous protein and cleaved caspase-1. Taken together, these results suggest that Plin2 liver-specific ablation alleviates diet-induced hepatic steatosis and inflammation via a PEMT-mediated mechanism that involves compensatory changes in proteins involved in phospholipid remodeling, inflammation, and ER stress that work to alleviate diet-induced NASH. Overall, these findings support a role for Plin2 as a target for NASH therapy.
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Affiliation(s)
- Charles P. Najt
- 1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan;
| | | | - Mohammad B. Aljazi
- 1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan;
| | - Kelly A. Fader
- 1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan;
| | - Sandra D. Olenic
- 1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan;
| | - Julienne R. L. Brock
- 1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan;
| | - Todd A. Lydic
- 2Department of Physiology, Michigan State University, East Lansing, Michigan; and
| | - A. Daniel Jones
- 1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan; ,3Department of Chemistry, Michigan State University, East Lansing, Michigan
| | - Barbara P. Atshaves
- 1Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan;
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Adamson SE, Griffiths R, Moravec R, Senthivinayagam S, Montgomery G, Chen W, Han J, Sharma PR, Mullins GR, Gorski SA, Cooper JA, Kadl A, Enfield K, Braciale TJ, Harris TE, Leitinger N. Disabled homolog 2 controls macrophage phenotypic polarization and adipose tissue inflammation. J Clin Invest 2016; 126:1311-22. [PMID: 26927671 DOI: 10.1172/jci79590] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/14/2016] [Indexed: 02/06/2023] Open
Abstract
Acute and chronic tissue injury results in the generation of a myriad of environmental cues that macrophages respond to by changing their phenotype and function. This phenotypic regulation is critical for controlling tissue inflammation and resolution. Here, we have identified the adaptor protein disabled homolog 2 (DAB2) as a regulator of phenotypic switching in macrophages. Dab2 expression was upregulated in M2 macrophages and suppressed in M1 macrophages isolated from both mice and humans, and genetic deletion of Dab2 predisposed macrophages to adopt a proinflammatory M1 phenotype. In mice with myeloid cell-specific deletion of Dab2 (Dab2fl/fl Lysm-Cre), treatment with sublethal doses of LPS resulted in increased proinflammatory gene expression and macrophage activation. Moreover, chronic high-fat feeding exacerbated adipose tissue inflammation, M1 polarization of adipose tissue macrophages, and the development of insulin resistance in DAB2-deficient animals compared with controls. Mutational analyses revealed that DAB2 interacts with TNF receptor-associated factor 6 (TRAF6) and attenuates IκB kinase β-dependent (IKKβ-dependent) phosphorylation of Ser536 in the transactivation domain of NF-κB p65. Together, these findings reveal that DAB2 is critical for controlling inflammatory signaling during phenotypic polarization of macrophages and suggest that manipulation of DAB2 expression and function may hold therapeutic potential for the treatment of acute and chronic inflammatory disorders.
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Najt CP, Lwande JS, McIntosh AL, Senthivinayagam S, Gupta S, Kuhn LA, Atshaves BP. Structural and functional assessment of perilipin 2 lipid binding domain(s). Biochemistry 2014; 53:7051-66. [PMID: 25338003 PMCID: PMC4238800 DOI: 10.1021/bi500918m] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 10/22/2014] [Indexed: 12/18/2022]
Abstract
Although perilipin 2 (Plin2) has been shown to bind lipids with high affinity, the Plin2 lipid binding site has yet to be defined. This is of interest since Plin2's affinity for lipids has been suggested to be important for lipid droplet biogenesis and intracellular triacylglycerol accumulation. To define these regions, mouse Plin2 and several deletion mutants expressed as recombinant proteins and in mammalian cells were assessed by molecular modeling, fluorescence binding, circular dichroic, and fluorescence resonance energy transfer techniques to identify the structural and functional requirements for lipid binding. Major findings of this study indicate (1) the N-terminal PAT domain does not bind cholesterol or stearic acid; (2) Plin2 residues 119-251, containing helix α4, the α-β domain, and part of helix α6 form a Plin3-like cleft found to be important for highest affinity lipid binding; (3) both stearic acid and cholesterol interact favorably with the Plin2 cleft formed by conserved residues in helix α6 and adjacent strands, which is common to all the active lipid-binding constructs; and (4) discrete targeting of the Plin2 mutants to lipid droplets supports Plin2 containing two independent, nonoverlapping lipid droplet targeting domains in its central and C-terminal sequences. Thus, the current work reveals specific domains responsible for Plin2-lipid interactions that involves the protein's lipid binding and targeting functions.
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Affiliation(s)
- Charles P. Najt
- Department
of Biochemistry and Molecular Biology and Department of Computer Science
and Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Joel S. Lwande
- Department
of Biochemistry and Molecular Biology and Department of Computer Science
and Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Avery L. McIntosh
- Physiology and Pharmacology, Texas A&M
University, TVMC College Station, Texas 77843-4466, United States
| | - Subramanian Senthivinayagam
- Department
of Biochemistry and Molecular Biology and Department of Computer Science
and Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Shipra Gupta
- Department
of Biochemistry and Molecular Biology and Department of Computer Science
and Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Leslie A. Kuhn
- Department
of Biochemistry and Molecular Biology and Department of Computer Science
and Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Barbara P. Atshaves
- Department
of Biochemistry and Molecular Biology and Department of Computer Science
and Engineering, Michigan State University, East Lansing, Michigan 48824, United States
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Senthivinayagam S, McIntosh AL, Moon KC, Atshaves BP. Plin2 inhibits cellular glucose uptake through interactions with SNAP23, a SNARE complex protein. PLoS One 2013; 8:e73696. [PMID: 24040030 PMCID: PMC3765312 DOI: 10.1371/journal.pone.0073696] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 07/25/2013] [Indexed: 11/19/2022] Open
Abstract
Although a link between excess lipid storage and aberrant glucose metabolism has been recognized for many years, little is known what role lipid storage droplets and associated proteins such as Plin2 play in managing cellular glucose levels. To address this issue, the influence of Plin2 on glucose uptake was examined using 2-NBD-Glucose and [(3)H]-2-deoxyglucose to show that insulin-mediated glucose uptake was decreased 1.7- and 1.8-fold, respectively in L cell fibroblasts overexpressing Plin2. Conversely, suppression of Plin2 levels by RNAi-mediated knockdown increased 2-NBD-Glucose uptake several fold in transfected L cells and differentiated 3T3-L1 cells. The effect of Plin2 expression on proteins involved in glucose uptake and transport was also examined. Expression of the SNARE protein SNAP23 was increased 1.6-fold while levels of syntaxin-5 were decreased 1.7-fold in Plin2 overexpression cells with no significant changes observed in lipid droplet associated proteins Plin1 or FSP27 or with the insulin receptor, GLUT1, or VAMP4. FRET experiments revealed a close proximity of Plin2 to SNAP23 on lipid droplets to within an intramolecular distance of 51 Å. The extent of targeting of SNAP23 to lipid droplets was determined by co-localization and co-immunoprecipitation experiments to show increased partitioning of SNAP23 to lipid droplets when Plin2 was overexpressed. Taken together, these results suggest that Plin2 inhibits glucose uptake by interacting with, and regulating cellular targeting of SNAP23 to lipid droplets. In summary, the current study for the first time provides direct evidence for the role of Plin2 in mediating cellular glucose uptake.
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Affiliation(s)
- Subramanian Senthivinayagam
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Avery L. McIntosh
- Veterinary Physiology and Pharmacology, Texas A&M University, College Station, Texas, United States of America
| | - Kenneth C. Moon
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Barbara P. Atshaves
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
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6
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McIntosh AL, Senthivinayagam S, Moon KC, Gupta S, Lwande JS, Murphy CC, Storey SM, Atshaves BP. Direct interaction of Plin2 with lipids on the surface of lipid droplets: a live cell FRET analysis. Am J Physiol Cell Physiol 2012; 303:C728-42. [PMID: 22744009 DOI: 10.1152/ajpcell.00448.2011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Despite increasing awareness of the health risks associated with excess lipid storage in cells and tissues, knowledge of events governing lipid exchange at the surface of lipid droplets remains unclear. To address this issue, fluorescence resonance energy transfer (FRET) was performed to examine live cell interactions of Plin2 with lipids involved in maintaining lipid droplet structure and function. FRET efficiencies (E) between CFP-labeled Plin2 and fluorescently labeled phosphatidylcholine, sphingomyelin, stearic acid, and cholesterol were quantitated on a pixel-by-pixel basis to generate FRET image maps that specified areas with high E (>60%) in lipid droplets. The mean E and the distance R between the probes indicated a high yield of energy transfer and demonstrated molecular distances on the order of 44-57 Å, in keeping with direct molecular contact. In contrast, FRET between CFP-Plin2 and Nile red was not detected, indicating that the CFP-Plin2/Nile red interaction was beyond FRET proximity (>100 Å). An examination of the effect of Plin2 on cellular metabolism revealed that triacylglycerol, fatty acid, and cholesteryl ester content increased while diacylglycerol remained constant in CFP-Plin2-overexpressing cells. Total phospholipids also increased, reflecting increased phosphatidylcholine and sphingomyelin. Consistent with these results, expression levels of enzymes involved in triacylglycerol, cholesteryl ester, and phospholipid synthesis were significantly upregulated in CFP-Plin2-expressing cells while those associated with lipolysis either decreased or were unaffected. Taken together, these data show for the first time that Plin2 interacts directly with lipids on the surface of lipid droplets and influences levels of key enzymes and lipids involved in maintaining lipid droplet structure and function.
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Affiliation(s)
- Avery L McIntosh
- Dept. of Biochemistry and Molecular Biology, Michigan State Univ., East Lansing, MI 48824, USA
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7
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Storey SM, McIntosh AL, Senthivinayagam S, Moon KC, Atshaves BP. The phospholipid monolayer associated with perilipin-enriched lipid droplets is a highly organized rigid membrane structure. Am J Physiol Endocrinol Metab 2011; 301:E991-E1003. [PMID: 21846905 PMCID: PMC3213997 DOI: 10.1152/ajpendo.00109.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The significance of lipid droplets (LD) in lipid metabolism, cell signaling, and membrane trafficking is increasingly recognized, yet the role of the LD phospholipid monolayer in LD protein targeting and function remains unknown. To begin to address this issue, two populations of LD were isolated by ConA sepharose affinity chromatography: 1) functionally active LD enriched in perilipin, caveolin-1, and several lipolytic proteins, including ATGL and HSL; and 2) LD enriched in ADRP and TIP47 that contained little to no lipase activity. Coimmunoprecipitation experiments confirmed the close association of caveolin and perilipin and lack of interaction between caveolin and ADRP, in keeping with the separation observed with the ConA procedure. The phospholipid monolayer structure was evaluated to reveal that the perilipin-enriched LD exhibited increased rigidity (less fluidity), as shown by increased cholesterol/phospholipid, Sat/Unsat, and Sat/MUFA ratios. These results were confirmed by DPH-TMA, NBD-cholesterol, and NBD-sphingomyelin fluorescence polarization studies. By structure and organization, the perilipin-enriched LD most closely resembled the adipocyte PM. In contrast, the ADRP/TIP47-enriched LD contained a more fluid monolayer membrane, reflecting decreased polarizations and lipid order based on phospholipid fatty acid analysis. Taken together, results indicate that perilipin and associated lipolytic enzymes target areas in the phospholipid monolayer that are highly organized and rigid, similar in structure to localized areas of the PM where cholesterol and fatty acid uptake and efflux occur.
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Affiliation(s)
- Stephen M Storey
- Department of Physiology and Pharmacology, Texas A & M University, Texas Veterinary Medical Center, College Station, Texas, USA
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Thylur RP, Senthivinayagam S, Campbell EM, Rangasamy V, Thorenoor N, Sondarva G, Mehrotra S, Mishra P, Zook E, Le PT, Rana A, Rana B. Mixed lineage kinase 3 modulates β-catenin signaling in cancer cells. J Biol Chem 2011; 286:37470-82. [PMID: 21880738 PMCID: PMC3199493 DOI: 10.1074/jbc.m111.298943] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Indexed: 12/21/2022] Open
Abstract
Expression of β-catenin is strictly regulated in normal cells via the glycogen synthase kinase 3β (GSK3β)- adenomatous polyposis coli-axin-mediated degradation pathway. Mechanisms leading to inactivation of this pathway (example: activation of Wnt/β-catenin signaling or mutations of members of the degradation complex) can result in β-catenin stabilization and activation of β-catenin/T-cell factor (TCF) signaling. β-Catenin-mediated cellular events are diverse and complex. A better understanding of the cellular signaling networks that control β-catenin pathway is important for designing effective therapeutic strategies targeting this axis. To gain more insight, we focused on determining any possible cross-talk between β-catenin and mixed lineage kinase 3 (MLK3), a MAPK kinase kinase member. Our studies indicated that MLK3 can induce β-catenin expression via post-translational stabilization in various cancer cells, including prostate cancer. This function of MLK3 was dependent on its kinase activity. MLK3 can interact with β-catenin and phosphorylate it in vitro. Overexpression of GSK3β-WT or the S9A mutant was unable to antagonize MLK3-induced stabilization, suggesting this to be independent of GSK3β pathway. Surprisingly, despite stabilizing β-catenin, MLK3 inhibited TCF transcriptional activity in the presence of both WT and S37A β-catenin. These resulted in reduced expression of β-catenin/TCF downstream targets Survivin and myc. Immunoprecipitation studies indicated that MLK3 did not decrease β-catenin/TCF interaction but promoted interaction between β-catenin and KLF4, a known repressor of β-catenin/TCF transcriptional activity. In addition, co-expression of MLK3 and β-catenin resulted in significant G(2)/M arrest. These studies provide a novel insight toward the regulation of β-catenin pathway, which can be targeted to control cancer cell proliferation, particularly those with aberrant activation of β-catenin signaling.
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Affiliation(s)
- Ramesh P. Thylur
- From the Departments of Medicine, Division of Gastroenterology, Hepatology, and Nutrition
| | | | | | | | - Nithyananda Thorenoor
- From the Departments of Medicine, Division of Gastroenterology, Hepatology, and Nutrition
| | | | | | - Prajna Mishra
- From the Departments of Medicine, Division of Gastroenterology, Hepatology, and Nutrition
| | | | | | - Ajay Rana
- Molecular Pharmacology and Therapeutics
- the Hines Veterans Affairs Medical Center, Hines, Illinois 60141
| | - Basabi Rana
- From the Departments of Medicine, Division of Gastroenterology, Hepatology, and Nutrition
- Cell and Molecular Physiology, Loyola University Chicago, Maywood, Ilinois 60153 and
- the Hines Veterans Affairs Medical Center, Hines, Illinois 60141
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Mishra P, Senthivinayagam S, Rana A, Rana B. Abstract 1724: Role of GSK-3beta in gastrin-induced migration of gastric cancer cells. Cancer Res 2010. [DOI: 10.1158/1538-7445.am10-1724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: Gastric cancers are a leading cause of death worldwide, mainly due to late detection and lack of effective therapeutic strategies. An immediate first step towards designing a safe and targeted therapeutic strategy would be to gain a better understanding of the pathobiology of these cancers. Of the different etiologic risk factors contributing to gastric cancer, Helicobacter pylori infection is the most recognized. The gastrointestinal peptide hormone gastrin also plays a significant role in mediating gastric cancer pathogenesis. Our earlier studies showed that amidated gastrin (G17) can induce proliferation in gastric cancer cells, via involvement of β-catenin and CREB. Our more recent work has been focused on elucidating the signaling mechanism by which G17 induces migratory responses in gastric cancer cells. These studies revealed that G17-induced migration is mediated via activation of JNK/MAPKinase pathway. To understand the role of other signaling molecules in mediating these responses, studies were designed here with the serine/threonine kinase Glycogen Synthase Kinase-3beta (GSK3β), which is known to regulate migratory pathways, via regulating expression of snail. Aim: These studies were undertaken to (i) determine any effect of G17 on GSK3β pathway, (ii) identify the downstream target of GSK3β and (iii) understand whether GSK3β plays any role in G17-induced migration. Methods: To address these, studies were designed with human gastric cancer cells (AGSE), overexpressing the gastrin CCKB receptor following incubation with G17. Wherever necessary, cells were pretreated with GSK3β specific inhibitor (AR-A014418) or transiently transfected with different GSK3β expression vectors or luciferase vectors. Changes in protein expression were estimated by Western Blot analysis utilizing appropriate antibodies, and the degree of changes in luciferase activity was estimated by luciferase assays. Results: Stimulation of AGSE cells with G17 resulted in a transient increase in GSK3βser9 phosphorylation (inactivation) associated with a parallel increase in AKTSer473 phosphorylation. G17 treatment also resulted in an increase in snail protein expression (GSK3β downstream) and promoter activation. Pharmacological inhibition of GSK3β with AR-A014418 increased snail expression in the absence of G17 and overexpression of phosphorylation deficient mutant of GSK3β (S9A) antagonized G17-induced snail promoter induction. In addition, ectopic overexpression of GSK3β-S9A antagonized G17-induced cell migration and MMP-7 promoter activation, with synergistic effects when overexpressed with a kinase deficient mutant of GSK3β (K/A). Conclusion: These studies indicate that GSK3β might be playing an important role in G17-induced migratory events via regulating snail and MMP7 expression. This pathway can be exploited further for developing anticancer therapies to target gastrin-related cancer pathways.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1724.
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Affiliation(s)
- Prajna Mishra
- 1Loyola Univ. Stritch School of Medicine, Maywood, IL
| | | | - Ajay Rana
- 1Loyola Univ. Stritch School of Medicine, Maywood, IL
| | - Basabi Rana
- 1Loyola Univ. Stritch School of Medicine, Maywood, IL
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Mishra P, Senthivinayagam S, Rangasamy V, Sondarva G, Rana B. Mixed lineage kinase-3/JNK1 axis promotes migration of human gastric cancer cells following gastrin stimulation. Mol Endocrinol 2010; 24:598-607. [PMID: 20150185 PMCID: PMC5419095 DOI: 10.1210/me.2009-0387] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 12/30/2009] [Indexed: 12/13/2022] Open
Abstract
Gastrin is a gastrointestinal peptide hormone, secreted by the gastric G cells and can exist as a fully processed amidated form (G17) or as unprocessed forms. All forms of gastrin possess trophic properties towards the gastrointestinal mucosa. An understanding of the signaling pathways involved is important to design therapeutic approaches to target gastrin-mediated cellular events. The studies described here were designed to identify the signaling pathways by which amidated gastrin (G17) mediates cancer cell migration. These studies indicated a time- and dose-dependent increase in gastric cancer cell migration after G17 stimulation, involving cholecystokinin 2 receptor. G17-induced migration was preceded by activation of MAPK pathways and was antagonized after pretreatment with SP600125, a pharmacological inhibitor of c-Jun-NH(2)-terminal kinase (JNK) pathway. Knockdown of endogenous JNK1 expression via small interference RNA (JNK1-siRNA) inhibited G17-induced phosphorylation of c-Jun and migration, and overexpression of wild-type JNK1 or constitutive active JNK1 promoted G17-induced migration. Studies designed to identify the MAPK kinase kinase member mediating JNK activation indicated the involvement of mixed lineage kinase-3 (MLK3), which was transiently activated upon G17 treatment. Inhibition of MLK3 pathway via a pan-MLK inhibitor or knockdown of MLK3 expression by MLK3-siRNA antagonized G17-induced migration. Incubation with G17 also resulted in an induction of matrix metalloproteinase 7 promoter activity, which is known to mediate migration and invasion pathways in cancer cells. Modulation of MLK3, JNK1, and c-Jun pathways modulated G17-induced matrix metalloproteinase 7 promoter activation. These studies indicate that the MLK3/JNK1 axis mediates G17-induced gastric cancer cell migration, which can be targeted for designing novel therapeutic strategies for treating gastric malignancies.
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Affiliation(s)
- Prajna Mishra
- Division of Gastroenterology, Hepatology and Nutrition, Loyola University Chicago, 2160 South First Avenue, Maywood, Illinois 60153, USA
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Senthivinayagam S, Mishra P, Paramasivam SK, Yallapragada S, Chatterjee M, Wong L, Rana A, Rana B. Caspase-mediated cleavage of beta-catenin precedes drug-induced apoptosis in resistant cancer cells. J Biol Chem 2009; 284:13577-13588. [PMID: 19289465 DOI: 10.1074/jbc.m900248200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A delicate balance between cell death and survival pathways maintains normal physiology, which is altered in many cancers, shifting the balance toward increased survival. Several studies have established a close connection between the Wnt/beta-catenin pathway and tumorigenesis, aberrant activation of which might contribute toward increased cancer cell growth and survival. Extensive research is underway to identify therapeutic agents that can induce apoptosis specifically in cancer cells with minimal collateral damage to normal cells. Although tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis specifically in tumor cells, many cancer cells develop resistance, which can be overcome by combinatorial treatment with other agents: for example, peroxisome proliferator-activated receptor gamma (PPARgamma) ligands. To identify the molecular target mediating combinatorial drug-induced apoptosis, we focused on beta-catenin, a protein implicated in oncogenesis. Our results show that co-treatment of TRAIL-resistant cancer cells with TRAIL and the PPARgamma ligand troglitazone leads to a reduction of beta-catenin expression, coinciding with maximal apoptosis. Modulation of beta-catenin levels via ectopic overexpression or small interference RNA-mediated gene silencing modulates drug-induced apoptosis, indicating involvement of beta-catenin in regulating this pathway. More in-depth studies indicated a post-translational mechanism, independent of glycogen synthase kinase-3beta activity regulating beta-catenin expression following combinatorial drug treatment. Furthermore, TRAIL- and troglitazone-induced apoptosis was preceded by a cleavage of beta-catenin, which was complete in a fully apoptotic population, and was mediated by caspases-3 and -8. These results demonstrate beta-catenin as a promising new target of drug-induced apoptosis, which can be targeted to sensitize apoptosis-resistant cancer cells.
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Affiliation(s)
- Subramanian Senthivinayagam
- Department of Medicine, Division of Gastroenterology, Hepatology & Nutrition Loyola University, Chicago, Maywood, Illinois 60153
| | - Prajna Mishra
- Department of Medicine, Division of Gastroenterology, Hepatology & Nutrition Loyola University, Chicago, Maywood, Illinois 60153
| | - Suresh Kanna Paramasivam
- Department of Medicine, Division of Gastroenterology, Hepatology & Nutrition Loyola University, Chicago, Maywood, Illinois 60153
| | - Srinivas Yallapragada
- Department of Internal Medicine, The Texas A&M University System-Health Science Center, College of Medicine, Temple, Texas 76504
| | - Malay Chatterjee
- Division of Biochemistry, Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India 700032
| | - Lucas Wong
- Division of Hematology/Oncology, Scott & White Hospital, Temple, Texas 76504
| | - Ajay Rana
- Department of Pharmacology and Experimental Therapeutics, Loyola University, Chicago, Maywood, Illinois 60153; Hines Veterans Affairs Medical Center, Hines, Illinois 60141
| | - Basabi Rana
- Department of Medicine, Division of Gastroenterology, Hepatology & Nutrition Loyola University, Chicago, Maywood, Illinois 60153; Department of Pharmacology and Experimental Therapeutics, Loyola University, Chicago, Maywood, Illinois 60153; Hines Veterans Affairs Medical Center, Hines, Illinois 60141.
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