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Lewis K, La Selva R, Maldonado E, Annis MG, Najyb O, Cepeda Cañedo E, Totten S, Hébert S, Sabourin V, Mirabelli C, Ciccolini E, Lehuédé C, Choinière L, Russo M, Avizonis D, Park M, St-Pierre J, Kleinman CL, Siegel PM, Ursini-Siegel J. p66ShcA promotes malignant breast cancer phenotypes by alleviating energetic and oxidative stress. Redox Biol 2024; 70:103028. [PMID: 38211442 PMCID: PMC10821068 DOI: 10.1016/j.redox.2024.103028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 01/02/2024] [Indexed: 01/13/2024] Open
Abstract
Significant efforts have focused on identifying targetable genetic drivers that support the growth of solid tumors and/or increase metastatic ability. During tumor development and progression to metastatic disease, physiological and pharmacological selective pressures influence parallel adaptive strategies within cancer cell sub-populations. Such adaptations allow cancer cells to withstand these stressful microenvironments. This Darwinian model of stress adaptation often prevents durable clinical responses and influences the emergence of aggressive cancers with increased metastatic fitness. However, the mechanisms contributing to such adaptive stress responses are poorly understood. We now demonstrate that the p66ShcA redox protein, itself a ROS inducer, is essential for survival in response to physiological stressors, including anchorage independence and nutrient deprivation, in the context of poor outcome breast cancers. Mechanistically, we show that p66ShcA promotes both glucose and glutamine metabolic reprogramming in breast cancer cells, to increase their capacity to engage catabolic metabolism and support glutathione synthesis. In doing so, chronic p66ShcA exposure contributes to adaptive stress responses, providing breast cancer cells with sufficient ATP and redox balance needed to withstand such transient stressed states. Our studies demonstrate that p66ShcA functionally contributes to the maintenance of aggressive phenotypes and the emergence of metastatic disease by forcing breast tumors to adapt to chronic and moderately elevated levels of oxidative stress.
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Affiliation(s)
- Kyle Lewis
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Department of Biochemistry, McGill University, Montreal, QC, Canada
| | - Rachel La Selva
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Elias Maldonado
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Matthew G Annis
- Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Ouafa Najyb
- Department of Biochemistry, McGill University, Montreal, QC, Canada; Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Eduardo Cepeda Cañedo
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Stephanie Totten
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Steven Hébert
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada
| | - Valérie Sabourin
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada
| | - Caitlynn Mirabelli
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Emma Ciccolini
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada
| | - Camille Lehuédé
- Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Luc Choinière
- Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Mariana Russo
- Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Daina Avizonis
- Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Morag Park
- Department of Biochemistry, McGill University, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada; Goodman Cancer Institute, McGill University, Montreal, QC, Canada; Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada
| | - Julie St-Pierre
- Department of Biochemistry, Microbiology and Immunology and Ottawa Institute of Systems Biology, University of Ottawa, ON, Canada
| | - Claudia L Kleinman
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Peter M Siegel
- Department of Biochemistry, McGill University, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada; Goodman Cancer Institute, McGill University, Montreal, QC, Canada; Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada
| | - Josie Ursini-Siegel
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada; Department of Biochemistry, McGill University, Montreal, QC, Canada; Division of Experimental Medicine, McGill University, Montreal, QC, Canada; Gerald Bronfman Department of Oncology, McGill University, Montreal, QC, Canada.
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Refet-Mollof E, Najyb O, Chermat R, Glory A, Lafontaine J, Wong P, Gervais T. Abstract B005: Hypoxic sarcoma spheroid on a chip: Insights into treatment response. Clin Cancer Res 2022. [DOI: 10.1158/1557-3265.sarcomas22-b005] [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
Context: Hypoxia is found in at least 47% of soft-tissue sarcoma (STS) patients and is known to be a major contributor to treatment resistance, metastasis progression and associated with poor prognosis. Indeed, expression of hypoxic proteins (HIF1-α, CAIX) in STS is associated with a shorter overall survival, and a shorter progression-free survival in patients. Specifically, Yang et al. demonstrated in 2017 that patients stratified by a 24-gene hypoxia signature had a poorer distant metastasis free survival. Nevertheless, hypoxia is seldom considered during treatment development due to the lack of a user-friendly way to culture naturally hypoxic 3D tumor models. Therefore, we developed a user-friendly in vitro preclinical tool allowing the study of natural chronic hypoxia and its effect on treatment response. Methods: Microfabrication technologies were used to design a microfluidic chip allowing culture, maintenance, treatment, and analysis of 240 STS naturally hypoxic spheroids (750µm of diameter). SK-LMS-1 Human leiomyosarcoma and STS117 (human primary undifferentiated pleomorphic sarcoma cells) spheroids were formed 48h after seeding. Gold-standard hypoxic protein Hypoxia Inducible Factor 1 alpha (HIF1- α) and Carbonic Anhydrase IX (CAIX) expression was assessed by Western Blot (WB). Spatial distribution of CAIX was assessed by immunofluorescence (IF). Based on the IF, an in silico model of the oxygen consumption of the spheroids was built using COMSOL. As a proof of concept, the spheroids were treated using two oxygen-dependent treatment: RT and hypoxia prodrug Tirapazamine (TPZ). DNA-damages were quantified using yH2AX in IF to assess treatment efficacy. Results: These spheroids on-a-chip are the largest to date (>750µm), and express gold-standard hypoxic protein CAIX in their core only, a feature absent in spheroids of 450µm of diameter of the same cell lines. HIF1-α expression patterns were cell line dependent. CAIX expression in SK-LMS-1 and STS117 large spheroids was respectively 7.8 and 24 times higher than in 450µm spheroids. Quantification of DNA damages (count of yH2AX foci/nuclei area in mm²) demonstrated that TPZ preferentially targets the hypoxic core. However, the response (DNA damages) to RT alone showed no evidence of radioresistance of the hypoxic regions, on samples fixed 24h after irradiation. A possible explanation could be that, in 24h, the oxygen-dependent DNA repair and the accumulation of DNA damages in hypoxic regions hide the oxygen-dependent radioresistance. Therefore, quantification of DNA damages with yH2AX 30min after irradiation is currently being investigated, as maximum DNA damage response has been shown to be observed at this time point. Our 750µm spheroids naturally display a hypoxic core expressing gold-standard hypoxic protein CAIX at 120µm of depth, a feature absent in smaller spheroids. Together, these results cement our microfluidic device and our spheroids as a potent fundamental and pre-clinical tool to explore the biology of hypoxia on 3D tumor model, its effects on treatment response.
Citation Format: Elena Refet-Mollof, Ouafa Najyb, Rodin Chermat, Audrey Glory, Julie Lafontaine, Philip Wong, Thomas Gervais. Hypoxic sarcoma spheroid on a chip: Insights into treatment response [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr B005.
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Affiliation(s)
| | - Ouafa Najyb
- 1Polytechnique Montréal - CRCHUM - ICM, Montréal, QC, Canada,
| | - Rodin Chermat
- 1Polytechnique Montréal - CRCHUM - ICM, Montréal, QC, Canada,
| | - Audrey Glory
- 1Polytechnique Montréal - CRCHUM - ICM, Montréal, QC, Canada,
| | | | - Philip Wong
- 2University of Toronto - Princess Margaret Cancer Centre, Toronto, ON, Canada
| | - Thomas Gervais
- 1Polytechnique Montréal - CRCHUM - ICM, Montréal, QC, Canada,
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Lafontaine J, Refet-Mollof E, Najyb O, Gervais T, Wong P. Cell Death Analysis in Cancer Spheroids from a Microfluidic Device. Methods Mol Biol 2022; 2543:13-25. [PMID: 36087255 DOI: 10.1007/978-1-0716-2553-8_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Microfluidic technology facilitates the generation of 3D spheroids from cancer cells, a more suitable model for preclinical therapeutic studies. This system opens the possibility to test many drugs combination at a low cost. Here we describe the use of microfluidic devices for cytotoxicity evaluation on cancer spheroids for the discovery of drugs that could be used in combination with radiotherapy. Device fabrication, preparation, and seeding are also covered. Cell death arising following treatment is detected and characterized according to spheroid size, colony formation assays, and flow cytometry analysis of apoptotic marker annexin V.
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Affiliation(s)
- Julie Lafontaine
- Institut du Cancer de Montréal (ICM), Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada
| | - Elena Refet-Mollof
- Institut du Cancer de Montréal (ICM), Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada
- Institute of Biomedical Engineering, École Polytechnique de MontrÉal, Montréal, QC, Canada
| | - Ouafa Najyb
- Institut du Cancer de Montréal (ICM), Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada
| | - Thomas Gervais
- Institut du Cancer de Montréal (ICM), Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada
- Institute of Biomedical Engineering, École Polytechnique de MontrÉal, Montréal, QC, Canada
- Department of Engineering Physics, École Polytechnique de MontrÉal, Montréal, Canada
| | - Philip Wong
- Institut du Cancer de Montréal (ICM), Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, QC, Canada.
- Département de Radio-Oncologie, Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, QC, Canada.
- Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada.
- Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
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Bavoux M, Kamio Y, Vigneux-Foley E, Lafontaine J, Najyb O, Refet-Mollof E, Carrier JF, Gervais T, Wong P. X-ray on chip: Quantifying therapeutic synergies between radiotherapy and anticancer drugs using soft tissue sarcoma tumor spheroids. Radiother Oncol 2021; 157:175-181. [DOI: 10.1016/j.radonc.2021.01.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 02/07/2023]
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Abstract
ApoD is a 25 to 30 kDa glycosylated protein, member of the lipocalin superfamily. As a transporter of several small hydrophobic molecules, its known biological functions are mostly associated to lipid metabolism and neuroprotection. ApoD is a multi-ligand, multi-function protein that is involved lipid trafficking, food intake, inflammation, antioxidative response and development and in different types of cancers. An important aspect of ApoD's role in lipid metabolism appears to involve the transport of arachidonic acid, and the modulation of eicosanoid production and delivery in metabolic tissues. ApoD expression in metabolic tissues has been associated positively and negatively with insulin sensitivity and glucose homeostasis in a tissue dependent manner. ApoD levels rise considerably in association with aging and neuropathologies such as Alzheimer's disease, stroke, meningoencephalitis, moto-neuron disease, multiple sclerosis, schizophrenia and Parkinson's disease. ApoD is also modulated in several animal models of nervous system injury/pathology.
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Affiliation(s)
- Eric Rassart
- Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Case Postale 8888, Succursale Centre-ville, Montréal, QC H3C 3P8, Canada.
| | - Frederik Desmarais
- Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Case Postale 8888, Succursale Centre-ville, Montréal, QC H3C 3P8, Canada; Laboratoire du Métabolisme Moléculaire des Lipides, Université du Québec à Montréal, Département des Sciences Biologiques, Case Postale 8888, Succursale Centre-ville, Montréal, QC H3C 3P8, Canada
| | - Ouafa Najyb
- Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Case Postale 8888, Succursale Centre-ville, Montréal, QC H3C 3P8, Canada
| | - Karl-F Bergeron
- Laboratoire du Métabolisme Moléculaire des Lipides, Université du Québec à Montréal, Département des Sciences Biologiques, Case Postale 8888, Succursale Centre-ville, Montréal, QC H3C 3P8, Canada
| | - Catherine Mounier
- Laboratoire du Métabolisme Moléculaire des Lipides, Université du Québec à Montréal, Département des Sciences Biologiques, Case Postale 8888, Succursale Centre-ville, Montréal, QC H3C 3P8, Canada
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Im YK, Najyb O, Gravel SP, McGuirk S, Ahn R, Avizonis DZ, Chénard V, Sabourin V, Hudson J, Pawson T, Topisirovic I, Pollak M, St-Pierre J, Ursini-Siegel J. Interplay between ShcA Signaling and PGC-1α Triggers Targetable Metabolic Vulnerabilities in Breast Cancer. Cancer Res 2018; 78:4826-4838. [DOI: 10.1158/0008-5472.can-17-3696] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 05/07/2018] [Accepted: 06/18/2018] [Indexed: 11/16/2022]
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Martineau C, Najyb O, Signor C, Rassart É, Moreau R. Apolipoprotein D deficiency is associated to high bone turnover, low bone mass and impaired osteoblastic function in aged female mice. Metabolism 2016; 65:1247-58. [PMID: 27506732 PMCID: PMC7094319 DOI: 10.1016/j.metabol.2016.05.007] [Citation(s) in RCA: 12] [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] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 03/26/2016] [Accepted: 05/10/2016] [Indexed: 11/25/2022]
Abstract
BACKGROUND Apolipoprotein D (ApoD) is a member of the lipocalin family known to transport small hydrophobic ligands. A major site of ApoD expression in mice is the central nervous system where evidence suggests that it plays a protective role. Gene expression of ApoD was reported in bone-forming osteoblasts but its impact on bone metabolism remains undocumented. METHODS We compared basic bone parameters of ApoD(-/-) (null) and transgenic (tg) mice to wild-type (wt) littermates through microCT and histochemistry, as well as ApoD expression and secretion in osteoblasts under various culture conditions through real-time PCR and immunoblotting. RESULTS ApoD-null females displayed progressive bone loss with aging, resulting in a 50% reduction in trabecular bone volume and a 23% reduction in cortical bone volume by 9months of age. Only cortical bone volume was significantly reduced in ApoD-null males by an average of 24%. Histochemistry indicated significantly higher osteoblast surface and number of osteoclasts in femora from ApoD-null females. ApoD gene expression was confirmed in primary cultures of bone marrow mesenchymal cells (MSC), with higher expression levels in MSC from females compared to males. ApoD-null MSC exhibited impaired proliferation and differentiation potentials. Moreover, exogenous ApoD partially rescued the osteogenic potential of null MSC, which were shown to readily uptake the protein from media. ApoD expression was upregulated under low proliferation conditions, by contact inhibition and osteoblastic differentiation in MC3T3-E1 osteoblast-like cells. CONCLUSION Our results indicate that ApoD influences bone metabolism in mice in a gender-specific manner, potentially through an auto-/paracrine pathway.
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Affiliation(s)
- Corine Martineau
- Laboratoire du Métabolisme Osseux, Centre BioMed, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada.
| | - Ouafa Najyb
- Laboratoire de Biologie Moléculaire, Centre BioMed, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Céline Signor
- Laboratoire du Métabolisme Osseux, Centre BioMed, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Éric Rassart
- Laboratoire de Biologie Moléculaire, Centre BioMed, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Robert Moreau
- Laboratoire du Métabolisme Osseux, Centre BioMed, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada
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Najyb O, Do Carmo S, Alikashani A, Rassart E. Apolipoprotein D Overexpression Protects Against Kainate-Induced Neurotoxicity in Mice. Mol Neurobiol 2016; 54:3948-3963. [PMID: 27271124 PMCID: PMC7091089 DOI: 10.1007/s12035-016-9920-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 05/03/2016] [Indexed: 01/23/2023]
Abstract
Excitotoxicity due to the excessive activation of glutamatergic receptors leads to neuronal dysfunction and death. Excitotoxicity has been implicated in the pathogenesis of a myriad of neurodegenerative diseases with distinct etiologies such as Alzheimer's and Parkinson's. Numerous studies link apolipoprotein D (apoD), a secreted glycoprotein highly expressed in the central nervous system (CNS), to maintain and protect neurons in various mouse models of acute stress and neurodegeneration. Here, we used a mouse model overexpressing human apoD in neurons (H-apoD Tg) to test the neuroprotective effects of apoD in the kainic acid (KA)-lesioned hippocampus. Our results show that apoD overexpression in H-apoD Tg mice induces an increased resistance to KA-induced seizures, significantly attenuates inflammatory responses and confers protection against KA-induced cell apoptosis in the hippocampus. The apoD-mediated protection against KA-induced toxicity is imputable in part to increased plasma membrane Ca2+ ATPase type 2 expression (1.7-fold), decreased N-methyl-D-aspartate receptor (NMDAR) subunit NR2B levels (30 %) and lipid metabolism alterations. Indeed, we demonstrate that apoD can attenuate intracellular cholesterol content in primary hippocampal neurons and in brain of H-apoD Tg mice. In addition, apoD can be internalised by neurons and this internalisation is accentuated in ageing and injury conditions. Our results provide additional mechanistic information on the apoD-mediated neuroprotection in neurodegenerative conditions.
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Affiliation(s)
- Ouafa Najyb
- Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Centre BioMed, Université du Québec à Montréal, Case Postale 8888, Succursale Centre-ville, Montréal, QC, H3C-3P8, Canada
| | - Sonia Do Carmo
- Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Centre BioMed, Université du Québec à Montréal, Case Postale 8888, Succursale Centre-ville, Montréal, QC, H3C-3P8, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Azadeh Alikashani
- Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Centre BioMed, Université du Québec à Montréal, Case Postale 8888, Succursale Centre-ville, Montréal, QC, H3C-3P8, Canada
| | - Eric Rassart
- Laboratoire de Biologie Moléculaire, Département des Sciences Biologiques, Centre BioMed, Université du Québec à Montréal, Case Postale 8888, Succursale Centre-ville, Montréal, QC, H3C-3P8, Canada.
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Labrie M, Lalonde S, Najyb O, Thiery M, Daneault C, Des Rosiers C, Rassart E, Mounier C. Apolipoprotein D Transgenic Mice Develop Hepatic Steatosis through Activation of PPARγ and Fatty Acid Uptake. PLoS One 2015; 10:e0130230. [PMID: 26083030 PMCID: PMC4470830 DOI: 10.1371/journal.pone.0130230] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [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: 12/03/2014] [Accepted: 05/18/2015] [Indexed: 12/27/2022] Open
Abstract
Transgenic mice (Tg) overexpressing human apolipoprotein D (H-apoD) in the brain are resistant to neurodegeneration. Despite the use of a neuron-specific promoter to generate the Tg mice, they expressed significant levels of H-apoD in both plasma and liver and they slowly develop hepatic steatosis and insulin resistance. We show here that hepatic PPARγ expression in Tg mice is increased by 2-fold compared to wild type (WT) mice. Consequently, PPARγ target genes Plin2 and Cide A/C are overexpressed, leading to increased lipid droplets formation. Expression of the fatty acid transporter CD36, another PPARgamma target, is also increased in Tg mice associated with elevated fatty acid uptake as measured in primary hepatocytes. Elevated expression of AMPK in the liver of Tg leads to phosphorylation of acetyl CoA carboxylase, indicating a decreased activity of the enzyme. Fatty acid synthase expression is also induced but the hepatic lipogenesis measured in vivo is not significantly different between WT and Tg mice. In addition, expression of carnitine palmitoyl transferase 1, the rate-limiting enzyme of beta-oxidation, is slightly upregulated. Finally, we show that overexpressing H-apoD in HepG2 cells in presence of arachidonic acid (AA), the main apoD ligand, increases the transcriptional activity of PPARγ. Supporting the role of apoD in AA transport, we observed enrichment in hepatic AA and a decrease in plasmatic AA concentration. Taken together, our results demonstrate that the hepatic steatosis observed in apoD Tg mice is a consequence of increased PPARγ transcriptional activity by AA leading to increased fatty acid uptake by the liver.
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Affiliation(s)
- Marilyne Labrie
- Centre de recherche BioMed, Département des Sciences Biologiques, Université du Québec, Montréal, Québec, H3C 3P8, Canada
| | - Simon Lalonde
- Centre de recherche BioMed, Département des Sciences Biologiques, Université du Québec, Montréal, Québec, H3C 3P8, Canada
| | - Ouafa Najyb
- Centre de recherche BioMed, Département des Sciences Biologiques, Université du Québec, Montréal, Québec, H3C 3P8, Canada
| | - Maxime Thiery
- Centre de recherche BioMed, Département des Sciences Biologiques, Université du Québec, Montréal, Québec, H3C 3P8, Canada
| | - Caroline Daneault
- Montreal Heart Institute Research Center, Montreal, Quebec, H1T 1C8,Canada
| | - Chrisitne Des Rosiers
- Department of Nutrition, Université de Montréal, Montréal, Québec, H3C 3J7,Canada
- Montreal Heart Institute Research Center, Montreal, Quebec, H1T 1C8,Canada
| | - Eric Rassart
- Centre de recherche BioMed, Département des Sciences Biologiques, Université du Québec, Montréal, Québec, H3C 3P8, Canada
| | - Catherine Mounier
- Centre de recherche BioMed, Département des Sciences Biologiques, Université du Québec, Montréal, Québec, H3C 3P8, Canada
- * E-mail:
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Abstract
Apolipoprotein D (apoD), a member of the lipocalin family, is a 29-kDa secreted glycoprotein that binds and transports small lipophilic molecules. Expressed in several tissues, apoD is up-regulated under different stress stimuli and in a variety of pathologies. Numerous studies have revealed that overexpression of apoD led to neuroprotection in various mouse models of acute stress and neurodegeneration. This multifunctional protein is internalized in several cells types, but the specific internalization mechanism remains unknown. In this study, we demonstrate that the internalization of apoD involves a specific cell surface receptor in 293T cells, identified as the transmembrane glycoprotein basigin (BSG, CD147); more particularly, its low glycosylated form. Our results show that internalized apoD colocalizes with BSG into vesicular compartments. Down-regulation of BSG disrupted the internalization of apoD in cells. In contrast, overexpression of basigin in SH-5YSY cells, which poorly express BSG, restored the uptake of apoD. Cyclophilin A, a known ligand of BSG, competitively reduced apoD internalization, confirming that BSG is a key player in the apoD internalization process. In summary, our results demonstrate that basigin is very likely the apoD receptor and provide additional clues on the mechanisms involved in apoD-mediated functions, including neuroprotection.
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Affiliation(s)
- Ouafa Najyb
- From the Laboratoire de Biologie Moléculaire and
| | - Louise Brissette
- Laboratoire du Métabolisme des Lipoprotéines, Département des Sciences Biologiques, Centre BioMed, Université du Québec à Montréal, Succursale Centre-ville, Montréal, Quebec H3C 3P8, Canada
| | - Eric Rassart
- From the Laboratoire de Biologie Moléculaire and
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