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Saratov GA, Belogurov AA, Kudriaeva AA. Myelin basic protein antagonizes the SARS-CoV-2 protein ORF3a-induced autophagy inhibition. Biochimie 2024; 225:1-9. [PMID: 38703943 DOI: 10.1016/j.biochi.2024.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/06/2024] [Accepted: 04/26/2024] [Indexed: 05/06/2024]
Abstract
Inhibition of autophagy is one of the hallmarks of the SARS-CoV-2 infection. Recently it was reported that SARS-CoV-2 protein ORF3a inhibits fusion of autophagosomes with lysosomes via interaction with VPS39 thus preventing binding of homotypic fusion and protein sorting (HOPS) complex to RAB7 GTPase. Here we report that myelin basic protein (MBP), a major structural component of the myelin sheath, binds ORF3a and is colocalized with it in mammalian cells. Co-expression of MBP with ORF3a restores autophagy in mammalian cells, inhibited by viral protein. Our data suggest that basic charge of MBP drives suppression of ORF3a-induced autophagy inhibition as its deaminated variants lost ability to bind ORF3a and counteract autophagy blockade. These results together with our recent findings, indicating that MBP interacts with structural components of the vesicle transport machinery-synaptosomal-associated protein 23 (SNAP23), vesicle-associated membrane protein 3 (VAMP3) and Sec1/Munc18-1 family members, may suggest protective role of the MBP in terms of the maintaining of protein traffic and autophagosome-lysosome fusion machinery in oligodendrocytes during SARS-CoV-2 infection. Finally, our data may indicate that deimination of MBP observed in the patients with multiple sclerosis (MS) may contribute to the previously reported worser outcomes of COVID-19 and increase of post-COVID-19 neurologic symptoms in patients with MS.
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Affiliation(s)
- George A Saratov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997, Moscow, Russia; Moscow Institute of Physics and Technology (national Research University), Phystech School of Biological and Medical Physics, 141701, Dolgoprudny, Moscow Region, Russia
| | - Alexey A Belogurov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997, Moscow, Russia; Russian University of Medicine, Department of Biological Chemistry, Ministry of Health of Russian Federation, 127473, Moscow, Russia.
| | - Anna A Kudriaeva
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997, Moscow, Russia.
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Hu H, Tjaden A, Knapp S, Antolin AA, Müller S. A machine learning and live-cell imaging tool kit uncovers small molecules induced phospholipidosis. Cell Chem Biol 2023; 30:1634-1651.e6. [PMID: 37797617 DOI: 10.1016/j.chembiol.2023.09.003] [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: 05/20/2023] [Revised: 08/09/2023] [Accepted: 09/14/2023] [Indexed: 10/07/2023]
Abstract
Drug-induced phospholipidosis (DIPL), characterized by excessive accumulation of phospholipids in lysosomes, can lead to clinical adverse effects. It may also alter phenotypic responses in functional studies using chemical probes. Therefore, robust methods are needed to predict and quantify phospholipidosis (PL) early in drug discovery and in chemical probe characterization. Here, we present a versatile high-content live-cell imaging approach, which was used to evaluate a chemogenomic and a lysosomal modulation library. We trained and evaluated several machine learning models using the most comprehensive set of publicly available compounds and interpreted the best model using SHapley Additive exPlanations (SHAP). Analysis of high-quality chemical probes extracted from the Chemical Probes Portal using our algorithm revealed that closely related molecules, such as chemical probes and their matched negative controls can differ in their ability to induce PL, highlighting the importance of identifying PL for robust target validation in chemical biology.
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Affiliation(s)
- Huabin Hu
- Centre for Cancer Drug Discovery, Division of Cancer Therapeutics, The Institute of Cancer Research, London, UK; Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, BMC, Box 596, SE-751 24 Uppsala, Sweden
| | - Amelie Tjaden
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe University, 60438 Frankfurt am Main, Germany; Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences, Johann Wolfgang Goethe University, 60438 Frankfurt am Main, Germany
| | - Stefan Knapp
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe University, 60438 Frankfurt am Main, Germany; Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences, Johann Wolfgang Goethe University, 60438 Frankfurt am Main, Germany
| | - Albert A Antolin
- Centre for Cancer Drug Discovery, Division of Cancer Therapeutics, The Institute of Cancer Research, London, UK; ProCURE, Catalan Institute of Oncology, Oncobell, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Catalonia Barcelona, Spain.
| | - Susanne Müller
- Institute of Pharmaceutical Chemistry, Johann Wolfgang Goethe University, 60438 Frankfurt am Main, Germany; Structural Genomics Consortium (SGC), Buchmann Institute for Life Sciences, Johann Wolfgang Goethe University, 60438 Frankfurt am Main, Germany.
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Different Sensitivity of Macrophages to Phospholipidosis Induction by Amphiphilic Cationic Drugs. Int J Mol Sci 2020; 21:ijms21218391. [PMID: 33182310 PMCID: PMC7664898 DOI: 10.3390/ijms21218391] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 10/31/2020] [Accepted: 11/06/2020] [Indexed: 12/17/2022] Open
Abstract
Phospholipidosis (PLD), the intracellular accumulation of phospholipids, is an adaptive response to toxic stimuli and serves as an important parameter in the biological assessment of compounds. Cationic amphiphilic drugs are the main inducers of PLD and may impair the function of alveolar macrophages. In vivo and in vitro models are used for PLD screening but the choice of the cellular model may be important because PLD develops in a cell- and species-specific manner. In this study, a panel of different staining (LysoSensor, Acridine Orange, Nile Red, HCS LipidTOX, LysoID) was evaluated in murine (DMBM-2, J774, RAW264.7) and human (THP-1, monocyte-derived macrophages from peripheral blood) cells to identify the most sensitive and easy to analyze staining method and to detect species-specific differences in the reaction pattern. Amiodarone and chloroquine served as inducers of PLD. High content screening was used to compare number, area, and intensity of the staining. Due to the fast staining protocol and the sensitivity of the detection, LysoID proved to be the most suitable dye of the testing. The lower induction of PLD by chloroquine reported in vivo was also seen in this study. THP-1 macrophages, followed by DMBM-2 cells, produced the most similar reaction pattern to human monocyte-derived macrophages.
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The Lysosomotropic Activity of Hydrophobic Weak Base Drugs is Mediated via Their Intercalation into the Lysosomal Membrane. Cells 2020; 9:cells9051082. [PMID: 32349204 PMCID: PMC7290590 DOI: 10.3390/cells9051082] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/11/2020] [Accepted: 04/20/2020] [Indexed: 12/13/2022] Open
Abstract
Lipophilic weak base therapeutic agents, termed lysosomotropic drugs (LDs), undergo marked sequestration and concentration within lysosomes, hence altering lysosomal functions. This lysosomal drug entrapment has been described as luminal drug compartmentalization. Consistent with our recent finding that LDs inflict a pH-dependent membrane fluidization, we herein demonstrate that LDs undergo intercalation and concentration within lysosomal membranes. The latter was revealed experimentally and computationally by (a) confocal microscopy of fluorescent compounds and drugs within lysosomal membranes, and (b) molecular dynamics modeling of the pH-dependent membrane insertion and accumulation of an assortment of LDs, including anticancer drugs. Based on the multiple functions of the lysosome as a central nutrient sensory hub and a degradation center, we discuss the molecular mechanisms underlying the alteration of morphology and impairment of lysosomal functions as consequences of LDs’ intercalation into lysosomes. Our findings bear important implications for drug design, drug induced lysosomal damage, diseases and pertaining therapeutics.
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Simpkins F, Jang K, Yoon H, Hew KE, Kim M, Azzam DJ, Sun J, Zhao D, Ince TA, Liu W, Guo W, Wei Z, Zhang G, Mills GB, Slingerland JM. Dual Src and MEK Inhibition Decreases Ovarian Cancer Growth and Targets Tumor Initiating Stem-Like Cells. Clin Cancer Res 2018; 24:4874-4886. [PMID: 29959144 PMCID: PMC6557165 DOI: 10.1158/1078-0432.ccr-17-3697] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/06/2018] [Accepted: 06/28/2018] [Indexed: 01/06/2023]
Abstract
Purpose: Rational targeted therapies are needed for treatment of ovarian cancers. Signaling kinases Src and MAPK are activated in high-grade serous ovarian cancer (HGSOC). Here, we tested the frequency of activation of both kinases in HGSOC and the therapeutic potential of dual kinase inhibition.Experimental Design: MEK and Src activation was assayed in primary HGSOC from The Cancer Genome Atlas (TGGA). Effects of dual kinase inhibition were assayed on cell-cycle, apoptosis, gene, and proteomic analysis; cancer stem cells; and xenografts.Results: Both Src and MAPK are coactivated in 31% of HGSOC, and this associates with worse overall survival on multivariate analysis. Frequent dual kinase activation in HGSOC led us to assay the efficacy of combined Src and MEK inhibition. Treatment of established lines and primary ovarian cancer cultures with Src and MEK inhibitors saracatinib and selumetinib, respectively, showed target kinase inhibition and synergistic induction of apoptosis and cell-cycle arrest in vitro, and tumor inhibition in xenografts. Gene expression and proteomic analysis confirmed cell-cycle inhibition and autophagy. Dual therapy also potently inhibited tumor-initiating cells. Src and MAPK were both activated in tumor-initiating populations. Combination treatment followed by drug washout decreased sphere formation and ALDH1+ cells. In vivo, tumors dissociated after dual therapy showed a marked decrease in ALDH1 staining, sphere formation, and loss of tumor-initiating cells upon serial xenografting.Conclusions: Selumetinib added to saracatinib overcomes EGFR/HER2/ERBB2-mediated bypass activation of MEK/MAPK observed with saracatinib alone and targets tumor-initiating ovarian cancer populations, supporting further evaluation of combined Src-MEK inhibition in clinical trials. Clin Cancer Res; 24(19); 4874-86. ©2018 AACR.
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Affiliation(s)
- Fiona Simpkins
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida.
- Department of Obstetrics & Gynecology, University of Miami, Miami, Florida
- Ovarian Cancer Research Center, Division of Gynecology Oncology, Department of Obstetrics & Gynecology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kibeom Jang
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, Florida
| | - Hyunho Yoon
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
| | - Karina E Hew
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
- Department of Obstetrics & Gynecology, University of Miami, Miami, Florida
| | - Minsoon Kim
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, Florida
| | - Diana J Azzam
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, Florida
| | - Jun Sun
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
| | - Dekuang Zhao
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
| | - Tan A Ince
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida
- Department of Pathology and Laboratory Medicine, University of Miami, Miami, Florida
- Interdisciplinary Stem Cell Institute, University of Miami, Miami, Florida
| | - Wenbin Liu
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Wei Guo
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Zhi Wei
- Department of Computer Science, New Jersey Institute of Technology, Newark, New Jersey
| | - Gao Zhang
- Wistar Institute, Philadelphia, Pennsylvania
| | - Gordon B Mills
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Joyce M Slingerland
- Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida.
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, Florida
- Department of Medicine, University of Miami, Miami, Florida
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Spaulding HR, Kelly EM, Quindry JC, Sheffield JB, Hudson MB, Selsby JT. Autophagic dysfunction and autophagosome escape in the mdx mus musculus model of Duchenne muscular dystrophy. Acta Physiol (Oxf) 2018; 222. [PMID: 28834378 DOI: 10.1111/apha.12944] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/09/2017] [Accepted: 08/15/2017] [Indexed: 01/19/2023]
Abstract
AIM Duchenne muscular dystrophy is caused by the absence of functional dystrophin protein and results in a host of secondary effects. Emerging evidence suggests that dystrophic pathology includes decreased pro-autophagic signalling and suppressed autophagic flux in skeletal muscle, but the relationship between autophagy and disease progression is unknown. The purpose of this investigation was to determine the extent to which basal autophagy changes with disease progression. We hypothesized that autophagy impairment would increase with advanced disease. METHODS To test this hypothesis, 7-week-old and 17-month-old dystrophic diaphragms were compared to each other and age-matched controls. RESULTS Changes in protein markers of autophagy indicate impaired autophagic stimulation through AMPK, however, robust pathway activation in dystrophic muscle, independent of disease severity. Relative protein abundance of p62, an inverse correlate of autophagic degradation, was dramatically elevated with disease regardless of age. Likewise, relative protein abundance of Lamp2, a lysosome marker, was decreased twofold at 17 months of age in dystrophic muscle and was confirmed, along with mislocalization, in histological samples, implicating lysosomal dysregulation in this process. In dystrophic muscle, autophagosome-sized p62-positive foci were observed in the extracellular space. Moreover, we found that autophagosomes were released from both healthy and dystrophic diaphragms into the extracellular environment, and the occurrence of autophagosome escape was more frequent in dystrophic muscle. CONCLUSION These findings suggest autophagic dysfunction proceeds independent of disease progression and blunted degradation of autophagosomes is due in part to decreased lysosome abundance, and contributes to autophagosomal escape to the extracellular space.
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Affiliation(s)
- H. R. Spaulding
- Department of Animal Science; Iowa State University; Ames IA USA
| | - E. M. Kelly
- Coriell Institute for Medical Research; Camden NJ USA
| | - J. C. Quindry
- Department of Health and Human Performance; University of Montana; Missoula MT USA
| | - J. B. Sheffield
- Department of Biology; Temple University; Philadelphia PA USA
| | - M. B. Hudson
- Department of Kinesiology and Applied Physiology; University of Delaware; Newark DE USA
| | - J. T. Selsby
- Department of Animal Science; Iowa State University; Ames IA USA
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The biological foundation of the genetic association of TOMM40 with late-onset Alzheimer's disease. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2973-2986. [PMID: 28768149 DOI: 10.1016/j.bbadis.2017.07.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 07/13/2017] [Accepted: 07/28/2017] [Indexed: 02/06/2023]
Abstract
A variable-length poly-T variant in intron 6 of the TOMM40 gene, rs10524523, is associated with risk and age-of-onset of sporadic (late-onset) Alzheimer's disease. In Caucasians, the three predominant alleles at this locus are Short (S), Long (L) or Very long (VL). On an APOE ε3/3 background, the S/VL and VL/VL genotypes are more protective than S/S. The '523 poly-T has regulatory properties, in that the VL poly-T results in higher expression than the S poly-T in luciferase expression systems. The aim of the current work was to identify effects on cellular bioenergetics of increased TOM40 protein expression. MitoTracker Green fluorescence and autophagic vesicle staining was the same in control and over-expressing cells, but TOM40 over-expression was associated with increased expression of TOM20, a preprotein receptor of the TOM complex, the mitochondrial chaperone HSPA9, and PDHE1a, and increased activities of the oxidative phosphorylation complexes I and IV and of the TCA member α-ketoglutaric acid dehydrogenase. Consistent with the complex I findings, respiration was more sensitive to inhibition by rotenone in control cells than in the TOM40 over-expressing cells. In the absence of inhibitors, total cellular ATP, the mitochondrial membrane potential, and respiration were elevated in the over-expressing cells. Spare respiratory capacity was greater in the TOM40 over-expressing cells than in the controls. TOM40 over-expression blocked Ab-elicited decreases in the mitochondrial membrane potential, cellular ATP levels, and cellular viability in the control cells. These data suggest elevated expression of TOM40 may be protective of mitochondrial function.
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Cui X, Luo Y, Li C, Li Y, Wang Z. Changes of intracellular Ca2+ in quercetin-induced autophagy progression. Acta Biochim Biophys Sin (Shanghai) 2015; 47:908-14. [PMID: 26423114 DOI: 10.1093/abbs/gmv096] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 07/29/2015] [Indexed: 12/22/2022] Open
Abstract
Quercetin was previously reported to exhibit significant anti-proliferative activities, and its major effect on tumors was to induce cell apoptosis or autophagy. However, the specific mechanism remains controversial. In this study, autophagy induced by quercetin was determined with various methods. Intracellular Ca2+ ([Ca2+]i) was measured after being incubated with Fluo-3 acetoxymethyl (AM). At the same time, the relationship between the intracellular Ca2+ and autophagy induced by quercetin was further analyzed. These results showed that autophagy induced by quercetin (0-50 µg/ml) in HepG2 cells was in a dose-dependent manner. Meanwhile, when autophagy was induced by quercetin, [Ca2+]i was significantly increased. And after being incubated with calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N-tetraacetic acid-AM, autophagy was suppressed, which implied that [Ca2+]i elevation appeared to be the cause for autophagy induction. These results suggested that calcium from intracellular calcium storage may play an important role in quercetin-induced autophagy.
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Affiliation(s)
- Xiaodong Cui
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan 030006, China
| | - Yanan Luo
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan 030006, China
| | - Chen Li
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan 030006, China
| | - Yuying Li
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan 030006, China
| | - Zhuanhua Wang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan 030006, China
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Identification of lysosomotropic compounds based on the distribution and size of lysosomes. Biochem Biophys Res Commun 2014; 450:189-94. [DOI: 10.1016/j.bbrc.2014.05.091] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 05/20/2014] [Indexed: 01/15/2023]
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Basu S, Rajakaruna S, Reyes B, Van Bockstaele E, Menko AS. Suppression of MAPK/JNK-MTORC1 signaling leads to premature loss of organelles and nuclei by autophagy during terminal differentiation of lens fiber cells. Autophagy 2014; 10:1193-211. [PMID: 24813396 PMCID: PMC4203547 DOI: 10.4161/auto.28768] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Although autophagic pathways are essential to developmental processes, many questions still remain regarding the initiation signals that regulate autophagy in the context of differentiation. To address these questions we studied the ocular lens, as the programmed elimination of nuclei and organelles occurs in a precisely regulated spatiotemporal manner to form the organelle-free zone (OFZ), a characteristic essential for vision acuity. Here, we report our discovery that inactivation of MAPK/JNK induces autophagy for formation of the OFZ through its regulation of MTORC1, where MAPK/JNK signaling is required for both MTOR activation and RPTOR/RAPTOR phosphorylation. Autophagy pathway proteins including ULK1, BECN1/Beclin 1, and MAP1LC3B2/LC3B-II were upregulated in the presence of inhibitors to either MAPK/JNK or MTOR, inducing autophagic loss of organelles to form the OFZ. These results reveal that MAPK/JNK is a positive regulator of MTORC1 signaling and its developmentally regulated inactivation provides an inducing signal for the coordinated autophagic removal of nuclei and organelles required for lens function.
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Affiliation(s)
- Subhasree Basu
- Department of Pathology, Anatomy and Cell Biology; Thomas Jefferson University; Philadelphia, PA USA
| | - Suren Rajakaruna
- Department of Pathology, Anatomy and Cell Biology; Thomas Jefferson University; Philadelphia, PA USA
| | - Beverly Reyes
- Department of Neuroscience; Farber Institute for Neuroscience; Thomas Jefferson University; Philadelphia, PA USA
| | - Elisabeth Van Bockstaele
- Department of Neuroscience; Farber Institute for Neuroscience; Thomas Jefferson University; Philadelphia, PA USA
| | - A Sue Menko
- Department of Pathology, Anatomy and Cell Biology; Thomas Jefferson University; Philadelphia, PA USA
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Cheong BHP, Lye JKK, Backhous S, Liew OW, Ng TW. Microplates based on liquid bridges between glass rods. J Colloid Interface Sci 2013; 397:177-84. [DOI: 10.1016/j.jcis.2013.01.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 01/23/2013] [Accepted: 01/23/2013] [Indexed: 11/29/2022]
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Simpkins F, Hevia-Paez P, Sun J, Ullmer W, Gilbert CA, da Silva T, Pedram A, Levin ER, Reis IM, Rabinovich B, Azzam D, Xu XX, Ince TA, Yang JY, Verhaak RGW, Lu Y, Mills GB, Slingerland JM. Src Inhibition with saracatinib reverses fulvestrant resistance in ER-positive ovarian cancer models in vitro and in vivo. Clin Cancer Res 2012; 18:5911-23. [PMID: 22896656 DOI: 10.1158/1078-0432.ccr-12-1257] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE More effective, less toxic treatments for recurrent ovarian cancer are needed. Although more than 60% of ovarian cancers express the estrogen receptor (ER), ER-targeted drugs have been disappointing due to drug resistance. In other estrogen-sensitive cancers, estrogen activates Src to phosphorylate p27 promoting its degradation and increasing cell-cycle progression. Because Src is activated in most ovarian cancers, we investigated whether combined Src and ER blockade by saracatinib and fulvestrant would circumvent antiestrogen resistance. EXPERIMENTAL DESIGN ER and Src were assayed in 338 primary ovarian cancers. Dual ER and Src blockade effects on cell cycle, ER target gene expression, and survival were assayed in ERα+ ovarian cancer lines, a primary human ovarian cancer culture in vitro, and on xenograft growth. RESULTS Most primary ovarian cancers express ER. Src activity was greater in ovarian cancer lines than normal epithelial lines. Estrogen activated Src, ER-Src binding, and ER translocation from cytoplasm to nucleus. Estrogen-mediated mitogenesis was via ERα, not ERβ. While each alone had little effect, combined saracatinib and fulvestrant increased p27 and inhibited cyclin E-Cdk2 and cell-cycle progression. Saracatinib also impaired induction of ER-target genes c-Myc and FOSL1; this was greatest with dual therapy. Combined therapy induced autophagy and more effectively inhibited ovarian cancer xenograft growth than monotherapy. CONCLUSIONS Saracatinib augments effects of fulvestrant by opposing estrogen-mediated Src activation and target gene expression, increasing cell-cycle arrest, and impairing survival, all of which would oppose antiestrogen resistance in these ER+ ovarian cancer models. These data support further preclinical and clinical evaluation of combined fulvestrant and saracatinib in ovarian cancer.
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Affiliation(s)
- Fiona Simpkins
- Braman Family Breast Cancer Institute and Division of Biostatistics, Department of Epidemiology and Public Health, University of Miami Sylvester Comprehensive Cancer Center, Miami, Florida 33136, USA
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Lu S, Jessen B, Strock C, Will Y. The contribution of physicochemical properties to multiple in vitro cytotoxicity endpoints. Toxicol In Vitro 2012; 26:613-20. [DOI: 10.1016/j.tiv.2012.01.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 01/28/2012] [Accepted: 01/31/2012] [Indexed: 12/16/2022]
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15
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Role of ATG8 and autophagy in programmed nuclear degradation in Tetrahymena thermophila. EUKARYOTIC CELL 2012; 11:494-506. [PMID: 22366125 DOI: 10.1128/ec.05296-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Autophagy is an evolutionarily conserved mechanism for the degradation of cellular components, but its role in enucleation during differentiation has not been established. Tetrahymena thermophila is a unicellular eukaryote with two functionally distinct nuclei, the somatic (macro-) and the germ line (micro-) nuclei. These nuclei are produced during sexual reproduction (conjugation), which involves differentiation and selective degradation of several specific nuclei. To examine the role of autophagy in nuclear degradation, we studied the function of two ATG8 genes in Tetrahymena. Through fluorescent protein tagging, we found that both proteins are targeted to degrading nuclei at specific stages, with some enrichment on the nuclear periphery, suggesting the formation of autophagosomes surrounding these nuclei. In addition, ATG8 knockout mutant cells showed a pronounced delay in nuclear degradation without apparently preventing the completion of other developmental events. This evidence provided direct support for a critical role for autophagy in programmed nuclear degradation. The results also showed differential roles for two ATG8 genes, with ATG8-65 playing a more significant role in starvation than ATG8-2, although both are important in nuclear degradation.
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