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Xu Y, Wang S, Xiong J, Zheng P, Zhang H, Chen S, Ma Q, Shen J, Velkov T, Dai C, Jiang H. Fe 3O 4-Incorporated Metal-Organic Framework for Chemo/Ferroptosis Synergistic Anti-Tumor via the Enhanced Chemodynamic Therapy. Adv Healthc Mater 2024; 13:e2303839. [PMID: 38334034 DOI: 10.1002/adhm.202303839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 01/24/2024] [Indexed: 02/10/2024]
Abstract
Metal-organic framework (MOF)-based drug delivery nanomaterials for cancer therapy have attracted increasing attention in recent years. Here, an enhanced chemodynamic anti-tumor therapy strategy by promoting the Fenton reaction by using core-shell zeolitic imidazolate framework-8 (ZIF-8)@Fe3O4 as a therapeutic platform is proposed. Carboxymethyl cellulose (CMC) is used as a stabilizer of Fe3O4, which is then decorated on the surface of ZIF-8 via the electrostatic interaction and serves as an efficient Fenton reaction trigger. Meanwhile, the pH-responsive ZIF-8 scaffold acts as a container to encapsulate the chemotherapeutic drug doxorubicin (DOX). The obtained DOX-ZIF-8@Fe3O4/CMC (DZFC) nanoparticles concomitantly accelerate DOX release and generate more hydroxyl radicals by targeting the lysosomes in cancer cells. In vitro and in vivo studies verify that the DZFC nanoparticles trigger glutathione peroxidase 4 (GPX4)-dependent ferroptosis via the activation of the c-Jun N-terminal kinases (JNK) signaling pathway, following to achieve the chemo/ferroptosis synergistic anti-tumor efficacy. No marked toxic effects are detected during DZFC treatment in a tumor-bearing mouse model. This composite nanoparticle remarkably suppresses the tumor growth with minimized systemic toxicity, opening new horizons for the next generation of theragnostic nanomedicines.
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Affiliation(s)
- Yuliang Xu
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
| | - Sihan Wang
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
| | - Jincheng Xiong
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
| | - Pimiao Zheng
- Department of Animal Pharmacy, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, Shandong, 271018, P. R. China
| | - Huixia Zhang
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
| | - Shiqi Chen
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
| | - Qiang Ma
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
| | - Jianzhong Shen
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
| | - Tony Velkov
- Department of Pharmacology, Biodiscovery Institute, Monash University, Victoria, 3800, Australia
| | - Chongshan Dai
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
| | - Haiyang Jiang
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, P.R. China
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Bae DH, Bae H, Yu HS, Dorjsembe B, No YH, Kim T, Kim NH, Kim JW, Kim J, Lee BS, Kim YJ, Park S, Khaleel ZH, Sa DH, Lee EC, Lee J, Ham J, Kim JC, Kim YH. Peptide-Drug Conjugate with Statistically Designed Transcellular Peptide for Psoriasis-Like Inflammation. Adv Healthc Mater 2024; 13:e2303480. [PMID: 38421096 DOI: 10.1002/adhm.202303480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 02/26/2024] [Indexed: 03/02/2024]
Abstract
Peptide-drug conjugates (PDCs) are a promising class of drug delivery systems that utilize covalently conjugated carrier peptides with therapeutic agents. PDCs offer several advantages over traditional drug delivery systems including enhanced target engagement, improved bioavailability, and increased cell permeability. However, the development of efficient transcellular peptides capable of effectively transporting drugs across biological barriers remains an unmet need. In this study, physicochemical criteria based on cell-penetrating peptides are employed to design transcellular peptides derived from an antimicrobial peptides library. Among the statistically designed transcellular peptides (SDTs), SDT7 exhibits higher skin permeability, faster kinetics, and improved cell permeability in human keratinocyte cells compared to the control peptide. Subsequently, it is found that 6-Paradol (PAR) exhibits inhibitory activity against phosphodiesterase 4, which can be utilized for an anti-inflammatory PDC. The transcellular PDC (SDT7-conjugated with PAR, named TM5) is evaluated in mouse models of psoriasis, exhibiting superior therapeutic efficacy compared to PAR alone. These findings highlight the potential of transcellular PDCs (TDCs) as a promising approach for the treatment of inflammatory skin disorders.
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Affiliation(s)
- Do Hyun Bae
- Department of Biomedical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
| | - Hayeon Bae
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Hyung-Seok Yu
- Natural Products Research Institute, Korea Institute of Science and Technology (KIST), Gangneung, 25451, Republic of Korea
| | - Banzragch Dorjsembe
- Natural Products Research Institute, Korea Institute of Science and Technology (KIST), Gangneung, 25451, Republic of Korea
- Division of Bio-Medical Science & Technology, University of Science and Technology (UST), Daejeon, 34113, Republic of Korea
| | - Young Hyun No
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Taejung Kim
- Natural Products Research Institute, Korea Institute of Science and Technology (KIST), Gangneung, 25451, Republic of Korea
- Division of Bio-Medical Science & Technology, University of Science and Technology (UST), Daejeon, 34113, Republic of Korea
| | - Nam Hyeong Kim
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Jin-Woo Kim
- Natural Products Research Institute, Korea Institute of Science and Technology (KIST), Gangneung, 25451, Republic of Korea
| | - Jiyool Kim
- Natural Products Research Institute, Korea Institute of Science and Technology (KIST), Gangneung, 25451, Republic of Korea
- Division of Bio-Medical Science & Technology, University of Science and Technology (UST), Daejeon, 34113, Republic of Korea
| | - Bok-Soo Lee
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Ye Ji Kim
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Seongchan Park
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Zinah Hilal Khaleel
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Deok Hyang Sa
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Eui-Chul Lee
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Jaecheol Lee
- School of Pharmacy, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Biopharmaceutical Convergence, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- IMNEWRUN Inc., Suwon, 16419, Republic of Korea
| | - Jungyeob Ham
- Natural Products Research Institute, Korea Institute of Science and Technology (KIST), Gangneung, 25451, Republic of Korea
- Division of Bio-Medical Science & Technology, University of Science and Technology (UST), Daejeon, 34113, Republic of Korea
| | - Jin-Chul Kim
- Natural Products Research Institute, Korea Institute of Science and Technology (KIST), Gangneung, 25451, Republic of Korea
- Division of Bio-Medical Science & Technology, University of Science and Technology (UST), Daejeon, 34113, Republic of Korea
| | - Yong Ho Kim
- Department of Biomedical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, 16419, Republic of Korea
- SKKU Advanced Institute of Nano Technology (SAINT), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- Department of Nano Science and Technology, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
- IMNEWRUN Inc., Suwon, 16419, Republic of Korea
- Department of Nano Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
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Sabnis N, Raut S, Nagarajan B, Kapic A, Dossou AS, Lothstein L, Fudala R, Bunnell BA, Lacko AG. A Spontaneous Assembling Lipopeptide Nanoconjugate Transporting the Anthracycline Drug N-Benzyladriamycin-14-valerate for Personalized Therapy of Ewing Sarcoma. Bioconjug Chem 2024; 35:187-202. [PMID: 38318778 DOI: 10.1021/acs.bioconjchem.3c00429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
To meet the current need for a tumor-selective, targeted therapy regimen associated with reduced toxicity, our laboratory has developed a spontaneously assembled nanostructure that resembles high-density lipoproteins (HDLs). These myristoyl-5A (MYR-5A) nanotransporters are designed to safely transport lipophilic pharmaceuticals, including a novel anthracycline drug (N-benzyladriamycin-14-valerate (AD198)). This formulation has been found to enhance the therapeutic efficacy and reduced toxicity of drugs in preclinical studies of 2D and 3D models of Ewing sarcoma (EWS) and cardiomyocytes. Our findings indicate that the MYR-5A/AD198 nanocomplex delivers its payload selectively to cancer cells via the scavenger receptor type B1 (SR-B1), thus providing a solid proof of concept for the development of an improved and highly effective, potentially personalized therapy for EWS while protecting against treatment-associated cardiotoxicity.
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Affiliation(s)
- Nirupama Sabnis
- Lipoprotein Drug Delivery Research Laboratory, Department of Microbiology, Immunology & Genetics, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
| | - Sangram Raut
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
| | - Bhavani Nagarajan
- North Texas Research Eye Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
| | - Ammar Kapic
- Lipoprotein Drug Delivery Research Laboratory, Department of Microbiology, Immunology & Genetics, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
| | - Akpedje Serena Dossou
- Lipoprotein Drug Delivery Research Laboratory, Department of Microbiology, Immunology & Genetics, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
| | - Leonard Lothstein
- Department of Pathology and Laboratory Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee 38103, United States
| | - Rafal Fudala
- Lipoprotein Drug Delivery Research Laboratory, Department of Microbiology, Immunology & Genetics, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
| | - Bruce A Bunnell
- Lipoprotein Drug Delivery Research Laboratory, Department of Microbiology, Immunology & Genetics, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
| | - Andras G Lacko
- Lipoprotein Drug Delivery Research Laboratory, Department of Microbiology, Immunology & Genetics, University of North Texas Health Science Center, Fort Worth, Texas 76107, United States
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da Costa Marques R, Hüppe N, Speth KR, Oberländer J, Lieberwirth I, Landfester K, Mailänder V. Proteomics reveals time-dependent protein corona changes in the intracellular pathway. Acta Biomater 2023; 172:355-368. [PMID: 37839632 DOI: 10.1016/j.actbio.2023.10.010] [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: 05/17/2023] [Revised: 10/04/2023] [Accepted: 10/06/2023] [Indexed: 10/17/2023]
Abstract
The intracellular protein corona has not been fully investigated in the field of nanotechnology-biology (nano-bio) interactions. To effectively understand intracellular protein corona formation and dynamics, we established a workflow to isolate the intracellular protein corona at different uptake times of two nanoparticles - magnetic hydroxyethyl starch nanoparticles (HES-NPs) and magnetic human serum albumin nanocapsules (HSA-NCs). We performed label-free quantitative LC-MS proteomics to analyze the composition of the intracellular protein corona and correlated our findings with results from conventional methods for intracellular trafficking of nanocarriers, such as flow cytometry, transmission electron microscopy (TEM), and confocal microscopy (cLSM). We determined the evolution of the intracellular protein corona. At different time stages the protein corona of the HES-NPs with a slower uptake changed, but there were fewer changes in that of the HSA-NCs with a more rapid uptake. We identified proteins that are involved in macropinocytosis (RAC1, ASAP2) as well as caveolin. This was confirmed by blocking experiments and by TEM studies. The investigated nanocarrier predominantly trafficked from early endosomes as determined by RAB5 identification in proteomics and in cLSM to late endosomes/lysosomes (RAB7, LAMP1, cathepsin K and HSP 90-beta) We further demonstrated differences between nanoparticles with slower and faster uptake kinetics and determined the associated proteome at different time points. Analysis of the intracellular protein corona provides us with effective data to examine the intracellular trafficking of nanocarriers used in efficient drug delivery and intracellular applications. STATEMENT OF SIGNIFICANCE: Many research papers focus on the protein corona on nanoparticles formed in biological fluids, but there are hardly any articles dealing with proteins that come in contact with nanoparticles inside cells. The "intracellular protein corona" studied here is a far more complex and highly demanding field. Most nanocarriers are designed to be taken up into cells. Given this, we chose two different nanocarriers to reveal changes in the proteins in dendritic cells during contact at specific times. Further studies will allow us to examine molecular target proteins using these methods. Our research is a significant addition towards the goal of understanding and thus improving the efficacy of drug nanocarriers.
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Affiliation(s)
- Richard da Costa Marques
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany; Dermatology Clinic, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany
| | - Natkritta Hüppe
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Kai R Speth
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany; Dermatology Clinic, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany
| | - Jennifer Oberländer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany; Dermatology Clinic, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany
| | - Ingo Lieberwirth
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Katharina Landfester
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Volker Mailänder
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany; Dermatology Clinic, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany.
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5
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Hivare P, Mujmer K, Swarup G, Gupta S, Bhatia D. Endocytic pathways of pathogenic protein aggregates in neurodegenerative diseases. Traffic 2023; 24:434-452. [PMID: 37392160 DOI: 10.1111/tra.12906] [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: 09/20/2022] [Revised: 05/14/2023] [Accepted: 06/11/2023] [Indexed: 07/03/2023]
Abstract
Endocytosis is the fundamental uptake process through which cells internalize extracellular materials and species. Neurodegenerative diseases (NDs) are characterized by a progressive accumulation of intrinsically disordered protein species, leading to neuronal death. Misfolding in many proteins leads to various NDs such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS) and other disorders. Despite the significance of disordered protein species in neurodegeneration, their spread between cells and the cellular uptake of extracellular species is not entirely understood. This review discusses the major internalization mechanisms of the different conformer species of these proteins and their endocytic mechanisms. We briefly introduce the broad types of endocytic mechanisms found in cells and then summarize what is known about the endocytosis of monomeric, oligomeric and aggregated conformations of tau, Aβ, α-Syn, Huntingtin, Prions, SOD1, TDP-43 and other proteins associated with neurodegeneration. We also highlight the key players involved in internalizing these disordered proteins and the several techniques and approaches to identify their endocytic mechanisms. Finally, we discuss the obstacles involved in studying the endocytosis of these protein species and the need to develop better techniques to elucidate the uptake mechanisms of a particular disordered protein species.
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Affiliation(s)
- Pravin Hivare
- Biological Engineering Discipline, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
| | - Kratika Mujmer
- Center for Brain and Cognitive Sciences, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
| | - Gitanjali Swarup
- Biological Engineering Discipline, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
| | - Sharad Gupta
- Biological Engineering Discipline, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
- Center for Biomedical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
| | - Dhiraj Bhatia
- Biological Engineering Discipline, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
- Center for Biomedical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gujarat, India
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6
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Banushi B, Joseph SR, Lum B, Lee JJ, Simpson F. Endocytosis in cancer and cancer therapy. Nat Rev Cancer 2023:10.1038/s41568-023-00574-6. [PMID: 37217781 DOI: 10.1038/s41568-023-00574-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/11/2023] [Indexed: 05/24/2023]
Abstract
Endocytosis is a complex process whereby cell surface proteins, lipids and fluid from the extracellular environment are packaged, sorted and internalized into cells. Endocytosis is also a mechanism of drug internalization into cells. There are multiple routes of endocytosis that determine the fate of molecules, from degradation in the lysosomes to recycling back to the plasma membrane. The overall rates of endocytosis and temporal regulation of molecules transiting through endocytic pathways are also intricately linked with signalling outcomes. This process relies on an array of factors, such as intrinsic amino acid motifs and post-translational modifications. Endocytosis is frequently disrupted in cancer. These disruptions lead to inappropriate retention of receptor tyrosine kinases on the tumour cell membrane, changes in the recycling of oncogenic molecules, defective signalling feedback loops and loss of cell polarity. In the past decade, endocytosis has emerged as a pivotal regulator of nutrient scavenging, response to and regulation of immune surveillance and tumour immune evasion, tumour metastasis and therapeutic drug delivery. This Review summarizes and integrates these advances into the understanding of endocytosis in cancer. The potential to regulate these pathways in the clinic to improve cancer therapy is also discussed.
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Affiliation(s)
- Blerida Banushi
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Shannon R Joseph
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Benedict Lum
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Jason J Lee
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Fiona Simpson
- Frazer Institute, University of Queensland, Woolloongabba, Queensland, Australia.
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Maguire E, Connor-Robson N, Shaw B, O’Donoghue R, Stöberl N, Hall-Roberts H. Assaying Microglia Functions In Vitro. Cells 2022; 11:3414. [PMID: 36359810 PMCID: PMC9654693 DOI: 10.3390/cells11213414] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 10/20/2022] [Accepted: 10/25/2022] [Indexed: 08/27/2023] Open
Abstract
Microglia, the main immune modulators of the central nervous system, have key roles in both the developing and adult brain. These functions include shaping healthy neuronal networks, carrying out immune surveillance, mediating inflammatory responses, and disposing of unwanted material. A wide variety of pathological conditions present with microglia dysregulation, highlighting the importance of these cells in both normal brain function and disease. Studies into microglial function in the context of both health and disease thus have the potential to provide tremendous insight across a broad range of research areas. In vitro culture of microglia, using primary cells, cell lines, or induced pluripotent stem cell derived microglia, allows researchers to generate reproducible, robust, and quantifiable data regarding microglia function. A broad range of assays have been successfully developed and optimised for characterizing microglial morphology, mediation of inflammation, endocytosis, phagocytosis, chemotaxis and random motility, and mediation of immunometabolism. This review describes the main functions of microglia, compares existing protocols for measuring these functions in vitro, and highlights common pitfalls and future areas for development. We aim to provide a comprehensive methodological guide for researchers planning to characterise microglial functions within a range of contexts and in vitro models.
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Affiliation(s)
- Emily Maguire
- UK Dementia Research Institute (UK DRI), School of Medicine, Cardiff University, Cardiff CF10 3AT, UK
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8
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Rennick JJ, Johnston APR, Parton RG. Key principles and methods for studying the endocytosis of biological and nanoparticle therapeutics. NATURE NANOTECHNOLOGY 2021; 16:266-276. [PMID: 33712737 DOI: 10.1038/s41565-021-00858-8] [Citation(s) in RCA: 493] [Impact Index Per Article: 164.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 01/19/2021] [Indexed: 05/20/2023]
Abstract
Endocytosis is a critical step in the process by which many therapeutic nanomedicines reach their intracellular targets. Our understanding of cellular uptake mechanisms has developed substantially in the past five years. However, these advances in cell biology have not fully translated to the nanoscience and therapeutics literature. Misconceptions surrounding the role of different endocytic pathways and how to study these pathways are hindering progress in developing improved nanoparticle therapies. Here, we summarize the latest insights into cellular uptake mechanisms and pathways. We highlight limitations of current systems to study endocytosis, particularly problems with non-specific inhibitors. We also summarize alternative genetic approaches to robustly probe these pathways and discuss the need to understand how cells endocytose particles in vivo. We hope that this critical assessment of the current methods used in studying nanoparticle uptake will guide future studies at the interface of cell biology and nanomedicine.
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Affiliation(s)
- Joshua J Rennick
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Brisbane, Queensland, Australia
| | - Angus P R Johnston
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia.
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Brisbane, Queensland, Australia.
| | - Robert G Parton
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Brisbane, Queensland, Australia.
- Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland, Australia.
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9
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Salazar ML, Jiménez JM, Villar J, Rivera M, Báez M, Manubens A, Becker MI. N-Glycosylation of mollusk hemocyanins contributes to their structural stability and immunomodulatory properties in mammals. J Biol Chem 2019; 294:19546-19564. [PMID: 31719148 PMCID: PMC6926458 DOI: 10.1074/jbc.ra119.009525] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 10/29/2019] [Indexed: 12/16/2022] Open
Abstract
Hemocyanins are widely used as carriers, adjuvants, and nonspecific immunostimulants in cancer because they promote Th1 immunity in mammals. Hemocyanins also interact with glycan-recognizing innate immune receptors on antigen-presenting cells, such as the C-type lectin immune receptors mannose receptor (MR), macrophage galactose lectin (MGL), and the Toll-like receptors (TLRs), stimulating proinflammatory cytokine secretion. However, the role of N-linked oligosaccharides on the structural and immunological properties of hemocyanin is unclear. Mollusk hemocyanins, such as Concholepas concholepas (CCH), Fissurella latimarginata (FLH), and Megathura crenulata (KLH), are oligomeric glycoproteins with complex dodecameric quaternary structures and heterogeneous glycosylation patterns, primarily consisting of mannose-rich N-glycans. Here, we report that enzyme-catalyzed N-deglycosylation of CCH, FLH, and KLH disrupts their quaternary structure and impairs their immunogenic effects. Biochemical analyses revealed that the deglycosylation does not change hemocyanin secondary structure but alters their refolding mechanism and dodecameric structure. Immunochemical analyses indicated decreased binding of N-deglycosylated hemocyanins to the MR and MGL receptors and TLR4 and reduced endocytosis concomitant with an impaired production of tumor necrosis factor α, and interleukins 6 and 12 (IL-6 and IL-12p40, respectively) in macrophages. Evaluating the function of N-deglycosylated hemocyanins in the humoral immune response and their nonspecific antitumor effects in the B16F10 melanoma model, we found that compared with native hemocyanins N-deglycosylated hemocyanins elicited reduced antibody titers, as well as partially diminished antitumor effects and altered carrier activities. In conclusion, the glycan content of hemocyanins is, among other structural characteristics, critically required for their immunological activities and should be considered in biomedical applications.
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Affiliation(s)
- Michelle L Salazar
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750269, Chile
| | - José M Jiménez
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750269, Chile
| | - Javiera Villar
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750269, Chile
| | - Maira Rivera
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380494, Chile
| | - Mauricio Báez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380494, Chile
| | - Augusto Manubens
- Departamento de Investigación y Desarrollo, Biosonda Corp., Santiago 7750269, Chile
| | - María Inés Becker
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750269, Chile .,Departamento de Investigación y Desarrollo, Biosonda Corp., Santiago 7750269, Chile
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10
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Koumakpayi IH, Le Page C, Delvoye N, Saad F, Mes-Masson AM. Macropinocytosis inhibitors and Arf6 regulate ErbB3 nuclear localization in prostate cancer cells. Mol Carcinog 2011; 50:901-12. [PMID: 21438025 DOI: 10.1002/mc.20766] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 02/10/2011] [Accepted: 02/13/2011] [Indexed: 01/08/2023]
Abstract
ErbB3 is a transmembrane tyrosine kinase receptor among the epidermal growth factor receptor (EGFR) family that plays an important role in prostate cancer (PCa) progression. We previously demonstrated that ErbB3 is located in the nucleus of PCa cell lines and PCa tissues. It also was observed that ErbB3 nuclear localization could discriminate between benign and malignant prostate tissues as well as between hormone sensitive and hormone-refractory PCa. Several studies have suggested a role for clathrin-mediated endosomal sorting in the nuclear localization of EGFR and ErbB2 but the mechanisms by which ErbB receptors escape recycling or degradation are not well known. Consequently to determine the role of endocytosis in the nuclear localization of ErbB3, different endocytotic inhibitors and specific si-RNAs were used to discriminate between clathrin-dependent and clathrin-independent pathways. We found that clathrin, caveolin, and membrane domains are not required for endocytosis-mediated nuclear localization of ErbB3 in PCa cells and we provide evidence that amiloride, a macropinocytosis inhibitor, and the ADP-ribosylation factor 6 (Arf6) are implicated in the compartimentalization of ErbB3. In conclusion, evidence for an endocytosis-based mechanism in the nuclear localization of ErbB3 in PCa cells is proposed. These results may help elucidate new therapeutic avenues in PCa that target nuclear ErbB3, which may participate in the progression and aggressivity of the disease.
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Affiliation(s)
- Ismaël Hervé Koumakpayi
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CR-CHUM) and Institut du Cancer de Montréal, Montreal, Quebec, Canada
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11
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Ueda S, Ogata S, Tsuda H, Kawarabayashi N, Kimura M, Sugiura Y, Tamai S, Matsubara O, Hatsuse K, Mochizuki H. The correlation between cytoplasmic overexpression of epidermal growth factor receptor and tumor aggressiveness: poor prognosis in patients with pancreatic ductal adenocarcinoma. Pancreas 2004; 29:e1-8. [PMID: 15211117 DOI: 10.1097/00006676-200407000-00061] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVES Recent studies have shown that some growth factor receptors with tyrosine kinase activity, eg, the epidermal growth factor receptor (EGFr) and the c-erbB-2 (HER-2) oncoprotein, are associated with aggressive biologic behavior of various cancer cell types. We examined the clinicopathological significance of the expression and localization of EGFr and HER-2 in both invasive and intraductal components of ductal adenocarcinomas of the pancreas. METHODS Tissue samples from 76 archival cases of pancreatic ductal adenocarcinoma were immunohistochemically analyzed for both membrane and cytoplasmic overexpression of EGFr and HER-2 oncoprotein. The rate of incidence between the invasive and intraductal components was analyzed and then their correlation with tumor differentiation and patient prognosis was analyzed. RESULTS Cytoplasmic EGFr overexpression was more frequent in invasive components (47 of 76, 62%) than in intraductal components (19 of 76, 25%), while membrane EGFr overexpression was more frequent in intraductal components (41 of 76, 54%) than in invasive components (11 of 76, 14%). The membrane HER-2 overexpression was also more frequent in intraductal components (15 of 76, 20%) than in invasive components (2 of 76, 3%), but the incidence of cytoplasmic HER-2 overexpression did not differ between intraductal components (12 of 76, 16%) and invasive components (8 of 76, 11%). The cytoplasmic EGFr overexpression in invasive components was more frequent in grade 3 group (32 of 33, 97%) than in grade 2 (15 of 32, 47%) and grade 1 groups (0 of 10, 0%) (P < 0.001). Patients with adenocarcinoma with cytoplasmic EGFr overexpression showed shorter overall survival than those with adenocarcinoma without cytoplasmic EGFr overexpression (P = 0.02). CONCLUSION It is suggested that the cytoplasmic overexpression of EGFr plays a significant role in the progression of pancreatic ductal adenocarcinoma, especially in the invasion and acquisition of aggressive clinical behavior. Both membrane and cytoplasmic expression of HER-2 showed no significant correlation between tumor differentiation and poor survival.
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Affiliation(s)
- Shigeto Ueda
- Surgery I, National Defense Medical College, Saitama, Japan
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12
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Marti U, Ruchti C, Kämpf J, Thomas GA, Williams ED, Peter HJ, Gerber H, Bürgi U. Nuclear localization of epidermal growth factor and epidermal growth factor receptors in human thyroid tissues. Thyroid 2001; 11:137-45. [PMID: 11288982 DOI: 10.1089/105072501300042785] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Epidermal growth factor (EGF) has widespread growth effects, and in some tissues proliferation is associated with the nuclear localization of EGF and epidermal growth factor receptor (EGFR). In the thyroid, EGF promotes growth but differs from thyrotropin (TSH) in inhibiting rather than stimulating functional parameters. We have therefore studied the occurrence and cellular distribution of EGF and EGFR in normal thyroid, in Graves' disease, where growth is mediated through the thyrotropin receptor (TSHR), and in a variety of human thyroid tumors. In the normal gland the staining was variable, but largely cytoplasmic, for both EGF and EGFR. In Graves' disease there was strong cytoplasmic staining for both EGF and EGFR, with frequent positive nuclei. Nuclear positivity for EGF and particularly for EGFR was also a feature of both follicular adenomas and follicular carcinomas. Interestingly, nuclear staining was almost absent in papillary carcinomas. These findings document for the first time the presence of nuclear EGF and EGFR in thyroid. Their predominant occurrence in tissues with increased growth (Graves' disease, follicular adenoma, and carcinoma) may indicate that nuclear EGF and EGFR play a role in growth regulation in these conditions. The absence of nuclear EGF and EGFR in papillary carcinomas would suggest that the role played by EGF in growth control differs between papillary carcinoma and follicular adenomas/carcinomas of the thyroid.
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Affiliation(s)
- U Marti
- Department of Clinical Chemistry, University Hospital, Bern, Switzerland.
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13
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Marti U, Wells A. The nuclear accumulation of a variant epidermal growth factor receptor (EGFR) lacking the transmembrane domain requires coexpression of a full-length EGFR. MOLECULAR CELL BIOLOGY RESEARCH COMMUNICATIONS : MCBRC 2000; 3:8-14. [PMID: 10683311 DOI: 10.1006/mcbr.2000.0177] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Both the epidermal growth factor (EGF) and its receptor (EGFR) accumulate in the nucleoplasm during liver regeneration. This localization in a nonmembraneous compartment presents a challenge in that the standard form of EGFR is a transmembrane protein and suggests the existence of a variant, soluble form of EGFR. To investigate the localization of such a putative EGFR splice variant, we generated a transmembrane-devoid form of EGFR. We placed this transmembrane-negative [TM(-)] EGFR construct and full-length wild-type (wt) EGFR either in a retroviral transfection vector or in an inducible expression vector. Mouse 3T3 cells, which express endogenous EGFR, were transfected with the TM(-) EGFR construct. The expression of these TM(-) EGFR, detected with a specific antibody against human EGFR using a confocal laser-scanning microscope, was predominantly found in the cytoplasm with no nuclear localization. After an overnight incubation with EGF the TM(-) EGFR accumulated in the nucleus. In mouse NR6 cells, which lack endogenous EGFR, transfected TM(-) EGFR were found in the cytoplasm, but incubation with EGF did not result in a nuclear accumulation of TM(-) EGFR. However, NR6 cells transfected with both TM(-) EGFR and wt EGFR showed nuclear accumulation after EGF treatment. These results suggest that both the wt EGFR and the TM(-) EGFR are required for nuclear accumulation of TM(-) EGFR and may implicate a model of homotypic recognition and translocation of a splice variant of EGFR.
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Affiliation(s)
- U Marti
- Endocrine and Diabetes Division, Department of Clincal Chemistry, University Hospital, Bern, CH-3010, Switzerland.
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14
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Abstract
Binding of ligand to the epidermal growth factor receptor (EGFR) initiates a series of processes including activation of the intrinsic EGFR tyrosine kinase, receptor autophosphorylation, and the assembly of active signaling complexes at the plasma membrane. Concomitantly, receptor trafficking is initiated, and the receptor is ultimately delivered to the lysosome, where it is degraded. Virtually all studies on EGFR trafficking have used fibroblasts and transformed cells. Because EGFR exerts a potent effect on the physiology of epithelial cells, we examined the regulation of EGFR activity and trafficking in nontransformed human mammary epithelial cells (HMEC). We found that HMEC that displayed a luminal phenotype were largely unresponsive to EGF and maintained a majority of their EGFR at the cell surface. In contrast, HMEC with a basal phenotype were highly responsive to EGF and, at steady state in the absence of exogenous ligand, distributed empty EGFR into intracellular pools. Maintenance of the intracellular pools was a direct consequence of specific and rapid endocytosis of the empty EGFR. The trafficking pattern was EGFR specific, used coated pits, and did not require receptor tyrosine kinase activity. Such an mechanism redistributes EGFR signaling potential among different membrane domains and into vesicles with unique biochemical microenviroments. In addition, our data show that EGFR endocytosis can be regulated in the absence of ligand binding and receptor activation in a cell-type-specific manner.
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Affiliation(s)
- P M Burke
- Department of Pathology, University of Utah, Salt Lake City 84132, USA
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15
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Nanbo A, Nishimura H, Muta T, Nagasawa S. Lipopolysaccharide stimulates HepG2 human hepatoma cells in the presence of lipopolysaccharide-binding protein via CD14. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 260:183-91. [PMID: 10091598 DOI: 10.1046/j.1432-1327.1999.00141.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Lipopolysaccharide (LPS)-binding protein (LBP), an opsonin for activation of macrophages by bacterial LPS, is synthesized in hepatocytes and is known to be an acute phase protein. Recently, cytokine-induced production of LBP was reported to increase 10-fold in hepatocytes isolated from LPS-treated rats, compared with those from normal rats. However, the mechanism by which the LPS treatment enhances the effect of cytokines remains to be clarified. In the present study, we examined whether LPS alone or an LPS/LBP complex directly stimulates the hepatocytes, leading to acceleration of the cytokine-induced LBP production. HepG2 cells (a human hepatoma cell line) were shown to express CD14, a glycosylphosphatidylinositol-anchored LPS receptor, by both RT/PCR and flow cytometric analyses. An LPS/LBP complex was an effective stimulator for LBP and CD14 production in HepG2 cells, but stimulation of the cells with either LPS or LBP alone did not significantly accelerate the production of these proteins. The findings were confirmed by semiquantitative RT/PCR analysis of mRNA levels of LBP and CD14 in HepG2 cells after stimulation with LPS alone and an LPS/LBP complex. In addition, two monoclonal antibodies (mAbs) to CD14 (3C10 and MEM-18) inhibited LPS/LBP-induced cellular responses of HepG2 cells. Furthermore, prestimulation of HepG2 cells with LPS/LBP augmented cytokine-induced production and gene expression of LBP and CD14. All these findings suggest that an LPS/LBP complex, but not free LPS, stimulates HepG2 cells via CD14 leading to increased basal and cytokine-induced LBP and CD14 production.
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Affiliation(s)
- A Nanbo
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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16
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Giovanazzi S, Accomazzo MR, Letari O, Oliva D, Nicosia S. Internalization and down-regulation of the prostacyclin receptor in human platelets. Biochem J 1997; 325 ( Pt 1):71-7. [PMID: 9224631 PMCID: PMC1218530 DOI: 10.1042/bj3250071] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The internalization of [3H]iloprost, a prostacyclin analogue, was studied in human platelets by binding studies. After incubation with [3H]iloprost at 37 degrees C, addition of unlabelled ligand at either 37 degrees C or 4 degrees C caused dissociation of 74% and 52% of the bound ligand respectively, suggesting that a portion had been internalized. The percentage of [3H]iloprost bound at equilibrium to the surface (evaluated by acid treatment) at either 37 degrees C or 4 degrees C was markedly different (80% versus 25%). Internalization was dependent on time and on the ligand nature and concentration. Energy-depleting agents (dinitrophenol and 2-deoxyglucose) completely inhibited internalization, whereas probenecid (inhibitor of organic anion transporters) did not affect it significantly. Subcellular fractionation indicated that, at 4 degrees C or in the absence of ligand, most of the receptor was present in membrane fractions (pellet at 27000 or 105000 g), whereas, when platelets were preincubated at 37 degrees C with iloprost, the receptor was found mainly in the cytosolic fraction. In platelets preincubated with iloprost at 4 degrees C, two classes of binding sites were present, whereas after preincubation at 37 degrees C only the lower-affinity sites were detected. After exposure to the agonist, iloprost-induced inhibition of platelet aggregation and activation of adenylate cyclase and cAMP production were significantly lower. Taken together, these data demonstrate that human platelets can internalize a high-affinity binding site for iloprost, presumably the prostacyclin receptor.
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Affiliation(s)
- S Giovanazzi
- Laboratory of Molecular Pharmacology, Institute of Pharmacological Sciences, University of Milan, via Balzaretti 9, 20133 Milan, Italy
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Soler C, Cragoe EJ, Soley M. Effects of epidermal growth factor on gluconeogenesis and cellular redox state do not require Na+/H+ exchange or Na+/K(+)-ATPase activities. REGULATORY PEPTIDES 1994; 52:1-6. [PMID: 7972927 DOI: 10.1016/0167-0115(94)90015-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Epidermal growth factor (EGF) triggers rapid and delayed effects on gluconeogenesis, cytosolic (lactate/pyruvate ratio) and mitochondrial (3-hydroxybutyrate/acetoacetate ratio) redox states (Soler, C. and Soley, M., Biochem. J., 294 (1993) 865-872). This study attempts to determine whether the mechanism by which EGF modulates any of these parameters is dependent on the regulation of Na+/H+ exchange and/or Na+/K(+)-ATPase activities. The Na+/H+ exchange was inhibited by either amiloride or the analogue 5-(N,N-hexamethylene)amiloride (HMA), and the Na+/K(+)-ATPase activity was inhibited by ouabain. The delayed EGF inhibition of gluconeogenesis, increase of the lactate/pyruvate ratio and decrease in the 3-hydroxybutyrate/acetoacetate ratio were unaltered in the presence of amiloride, HMA or ouabain. The rapid EGF stimulation of gluconeogenesis was also observed in the presence of HMA or ouabain. Although Na+/H+ exchange and/or Na+/K(+)-ATPase are regulated by EGF, our results indicate that these activities are not required for the effects of EGF on gluconeogenesis and/or cytosolic and mitochondrial redox state.
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Affiliation(s)
- C Soler
- Departament de Bioquímica i Fisiologia, Universitat de Barcelona, Spain
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18
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Gladhaug IP, Refsnes M, Christoffersen T. Regulation of surface expression of high-affinity receptors for epidermal growth factor (EGF) in hepatocytes by hormones, differentiating agents, and phorbol ester. Dig Dis Sci 1992; 37:233-9. [PMID: 1735341 DOI: 10.1007/bf01308177] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Freshly isolated adult rat hepatocytes exhibit a nonhomogeneous population of epidermal growth factor (EGF) receptors with about 10,000 high-affinity binding sites (Kd 20 pM) and about 200,000 low-affinity sites (Kd 600 pM) per cell. With culturing as primary monolayers under conditions where the cells show a marked increase in the sensitivity to the growth-stimulatory effect of EGF, a gradual reduction in the number of EGF receptors and an almost complete loss of high-affinity EGF receptors is seen. Insulin, which promotes growth of hepatocytes in concert with EGF, enhances the down-regulation of these high-affinity receptors. The differentiating (and growth-inhibitory) agent n-butyrate counteracts this down-regulation and preserves the high-affinity receptors. This effect of butyrate is synergistic with the glucocorticoid agent dexamethasone. Another differentiating agent, dimethylsulfoxide (DMSO), also counteracts the down-regulation of high-affinity EGF receptors. Moreover, the tumor promoter, tetradecanoylphorbol acetate (TPA), down-regulates the EGF receptor. This effect is particularly evident when studying the high-affinity receptors up-regulated by prior treatment with butyrate plus dexamethasone. Taken together these results provide strong support for the notion that an inverse relationship exists between expression of high-affinity EGF binding and responsiveness to growth activation by EGF.
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Affiliation(s)
- I P Gladhaug
- Department of Pharmacology, Faculty of Medicine, University of Oslo, Norway
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