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van Heerden D, Klima S, van den Bout I. How nuclear envelope dynamics can direct laminopathy phenotypes. Curr Opin Cell Biol 2024; 86:102290. [PMID: 38048657 DOI: 10.1016/j.ceb.2023.102290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/25/2023] [Accepted: 11/09/2023] [Indexed: 12/06/2023]
Abstract
The nuclear envelope separates the genome from the cytoplasmic environment. However, the nuclear envelope is also physically associated with the genome and exerts influence on gene expression and genome modification. The nucleus is dynamic, changing shape and responding to cell movement, disassembling and assembling during cell division, and undergoing rupture and repair. These dynamics can be impacted by genetic disease, leading to a family of diseases called laminopathies. Their disparate phenotypes suggest that multiple processes are affected. We highlight three such processes here, which we believe can be used to classify most of the laminopathies. While much still needs to be learned, some commonalities between these processes, such as proteins involved in nuclear envelope formation and rupture repair, may drive a variety of laminopathies. Here we review the latest information regarding nuclear dynamics and its role in laminopathies related to mutations in the nuclear lamina and linker of nucleoskeleton and cytoskeleton complex (LINC) proteins.
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Affiliation(s)
- David van Heerden
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, South Africa; Centre for Neuroendocrinology, Department of Immunology, Faculty of Health Sciences, University of Pretoria, South Africa
| | - Stefanie Klima
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, South Africa; Centre for Neuroendocrinology, Department of Immunology, Faculty of Health Sciences, University of Pretoria, South Africa
| | - Iman van den Bout
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, South Africa; Centre for Neuroendocrinology, Department of Immunology, Faculty of Health Sciences, University of Pretoria, South Africa.
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Grobbelaar S, Mercier AE, van den Bout I, Durandt C, Pepper MS. Considerations for enhanced mesenchymal stromal/stem cell myogenic commitment in vitro. Clin Transl Sci 2024; 17:e13703. [PMID: 38098144 PMCID: PMC10787211 DOI: 10.1111/cts.13703] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/16/2023] [Accepted: 12/09/2023] [Indexed: 01/15/2024] Open
Abstract
The generation of tissue from stem cells is an alluring concept as it holds a number of potential applications in clinical therapeutics and regenerative medicine. Mesenchymal stromal/stem cells (MSCs) can be isolated from a number of different somatic sources, and have the capacity to differentiate into adipogenic, osteogenic, chondrogenic, and myogenic lineages. Although the first three have been extensively investigated, there remains a paucity of literature on the latter. This review looks at the various strategies available in vitro to enhance harvested MSC commitment and differentiation into the myogenic pathway. These include chemical inducers, myogenic-enhancing cell culture substrates, and mechanical and dynamic culturing conditions. Drawing on information from embryonic and postnatal myogenesis from somites, satellite, and myogenic progenitor cells, the mechanisms behind the chemical and mechanical induction strategies can be studied, and the sequential gene and signaling cascades can be used to monitor the progression of myogenic differentiation in the laboratory. Increased understanding of the stimuli and signaling mechanisms in the initial stages of MSC myogenic commitment will provide tools with which we can enhance their differentiation efficacy and advance the process to clinical translation.
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Affiliation(s)
- Simone Grobbelaar
- Department of Physiology, School of Medicine, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
- Institute for Cellular and Molecular Medicine, Department of Immunology, and South African Medical Research Council Extramural Unit for Stem Cell Research and Therapy, School of Medicine, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
| | - Anne E. Mercier
- Department of Physiology, School of Medicine, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
| | - Iman van den Bout
- Department of Physiology, School of Medicine, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
- Centre for Neuroendocrinology, Department of Immunology, School of Medicine, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
| | - Chrisna Durandt
- Institute for Cellular and Molecular Medicine, Department of Immunology, and South African Medical Research Council Extramural Unit for Stem Cell Research and Therapy, School of Medicine, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
| | - Michael S. Pepper
- Institute for Cellular and Molecular Medicine, Department of Immunology, and South African Medical Research Council Extramural Unit for Stem Cell Research and Therapy, School of Medicine, Faculty of Health SciencesUniversity of PretoriaPretoriaSouth Africa
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Ncube KN, Jurgens T, Steenkamp V, Cromarty AD, van den Bout I, Cordier W. Comparative Evaluation of the Cytotoxicity of Doxorubicin in BT-20 Triple-Negative Breast Carcinoma Monolayer and Spheroid Cultures. Biomedicines 2023; 11:biomedicines11051484. [PMID: 37239157 DOI: 10.3390/biomedicines11051484] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/10/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023] Open
Abstract
Three-dimensional cell culture models are increasingly adopted as preferred pre-clinical drug testing platforms, as they circumvent limitations associated with traditional monolayer cell cultures. However, many of these models are not fully characterized. This study aimed to characterize a BT-20 triple-negative breast carcinoma spheroid model and assess its susceptibility to doxorubicin in comparison to a monolayer model. Spheroids were developed using the liquid overlay method. Phenotypic attributes were analyzed by characterizing changes in size, gross morphology, protein content, metabolic activity, hypoxic status, and cell-cell junctions. The cytotoxic range of doxorubicin in monolayers was determined using the sulforhodamine B assay, and the comparative effect of toxic and sub-toxic concentrations was assessed in both spheroids and monolayers. Similar to the in vivo microenvironment, spheroids had a heterogeneous spatial cytoarchitecture, inherent hypoxia and strong adherens junctions. Doxorubicin induced dose-dependent cytotoxicity in monolayers (IC25: 130 nM, IC50: 320 nM and IC75: 1580 nM); however, these concentrations did not alter the spheroid size or acid phosphatase activity. Only concentrations ≥6 µM had any effect on spheroid integrity. In comparison to monolayers, the BT-20 spheroid model has decreased sensitivity to doxorubicin and could serve as a better model for susceptibility testing in triple-negative breast cancer.
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Affiliation(s)
- Keith N Ncube
- Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, Pretoria 0007, South Africa
| | - Tamarin Jurgens
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria 0007, South Africa
| | - Vanessa Steenkamp
- Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, Pretoria 0007, South Africa
| | - Allan D Cromarty
- Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, Pretoria 0007, South Africa
| | - Iman van den Bout
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria 0007, South Africa
- Centre for Neuroendocrinology, Department of Immunology, University of Pretoria, Pretoria 0007, South Africa
| | - Werner Cordier
- Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, Pretoria 0007, South Africa
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Richards GA, Theron AJ, van den Bout I, Anderson R, Feldman C, van Zyl Smit R, Chang JW, Tintinger GR. Comparison of the effects of electronic cigarette vapours and tobacco smoke extracts on human neutrophils in vitro. ERJ Open Res 2023; 9:00502-2022. [PMID: 37228295 PMCID: PMC10204819 DOI: 10.1183/23120541.00502-2022] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/17/2023] [Indexed: 05/27/2023] Open
Abstract
Background Electronic cigarettes (ECs) are electronic aerosol delivery systems composed of nicotine and various chemicals, which are widely used to facilitate smoking cessation. Although ECs are considered safer than cigarettes, they do, however, contain chemical toxicants, some of which may interact with cells of the host's innate immune system of which neutrophils constitute a key component. Methods The current study was designed to compare the effects of aqueous EC aerosol extracts (ECEs; with or without nicotine) with those of cigarette smoke extract (CSE) on neutrophil and platelet reactivity in vitro. Neutrophil reactivity is characterised by the generation of reactive oxygen species (ROS), degranulation (elastase release) and the release of extracellular DNA (neutrophil extracellular trap (NET) formation: NETosis), which were measured using chemiluminescence, spectrophotometric and microscopic procedures, respectively. Platelet reactivity was measured according to the magnitude of upregulated expression of the adhesion molecule CD62P on activated cells using a flow cytometric procedure. Results Exposure of neutrophils to either ECEs or CSE caused a significant inhibition of ROS generation and elastase release by N-formyl-l-methionyl-l-leucyl-l-phenylalanine (1 µM)-activated neutrophils. Pre-treatment of neutrophils with CSE also resulted in a marked attenuation of phorbol 12-myristate 13-acetate (6.25 nM)-mediated release of extracellular DNA, which was unaffected by the ECEs. Similarly, CSE, but not the ECEs, inhibited the expression of CD62P by platelets activated with ADP (100 µM). Conclusions These observations suggest that ECE aerosols may inhibit some of the immuno-protective activities of neutrophils such as ROS production and elastase release by activated cells, the effect of which was not enhanced by inclusion of nicotine. The inhibitory effects of CSE were significantly more pronounced than those of ECEs, especially so for suppression of NET formation and platelet activation. If operative in vivo, these harmful immunosuppressive effects of ECEs may compromise intrinsic pulmonary antimicrobial defence mechanisms, albeit less so than cigarette smoke.
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Affiliation(s)
- Guy A. Richards
- Division of Critical Care, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Annette J. Theron
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Iman van den Bout
- Centre of Neuroendocrinology, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Ronald Anderson
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Charles Feldman
- Department of Internal Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Richard van Zyl Smit
- Department of Medicine, University of Cape Town, Groote Schuur Hospital, Cape Town, South Africa
| | - Ju-Wei Chang
- Department of Medicine, University of Cape Town, Groote Schuur Hospital, Cape Town, South Africa
| | - Gregory R. Tintinger
- Department of Internal Medicine, Steve Biko Academic Hospital and Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
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Anderson RC, Hanyroup S, Song YB, Mohamed-Moosa Z, van den Bout I, Schwulst AC, Kaiser UB, Millar RP, Newton CL. Functional Rescue of Inactivating Mutations of the Human Neurokinin 3 Receptor Using Pharmacological Chaperones. Int J Mol Sci 2022; 23:ijms23094587. [PMID: 35562976 PMCID: PMC9100388 DOI: 10.3390/ijms23094587] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 12/04/2022] Open
Abstract
G protein-coupled receptors (GPCRs) facilitate the majority of signal transductions across cell membranes in humans, with numerous diseases attributed to inactivating GPCR mutations. Many of these mutations result in misfolding during nascent receptor synthesis in the endoplasmic reticulum (ER), resulting in intracellular retention and degradation. Pharmacological chaperones (PCs) are cell-permeant small molecules that can interact with misfolded receptors in the ER and stabilise/rescue their folding to promote ER exit and trafficking to the cell membrane. The neurokinin 3 receptor (NK3R) plays a pivotal role in the hypothalamic–pituitary–gonadal reproductive axis. We sought to determine whether NK3R missense mutations result in a loss of cell surface receptor expression and, if so, whether a cell-permeant small molecule NK3R antagonist could be repurposed as a PC to restore function to these mutants. Quantitation of cell surface expression levels of seven mutant NK3Rs identified in hypogonadal patients indicated that five had severely impaired cell surface expression. A small molecule NK3R antagonist, M8, increased cell surface expression in four of these five and resulted in post-translational receptor processing in a manner analogous to the wild type. Importantly, there was a significant improvement in receptor activation in response to neurokinin B (NKB) for all four receptors following their rescue with M8. This demonstrates that M8 may have potential for therapeutic development in the treatment of hypogonadal patients harbouring NK3R mutations. The repurposing of existing small molecule GPCR modulators as PCs represents a novel and therapeutically viable option for the treatment of disorders attributed to mutations in GPCRs that cause intracellular retention.
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Affiliation(s)
- Ross C. Anderson
- Centre for Neuroendocrinology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa; (S.H.); (Z.M.-M.); (I.v.d.B.); (A.C.S.); (R.P.M.); (C.L.N.)
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa
- Correspondence:
| | - Sharika Hanyroup
- Centre for Neuroendocrinology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa; (S.H.); (Z.M.-M.); (I.v.d.B.); (A.C.S.); (R.P.M.); (C.L.N.)
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa
| | - Yong Bhum Song
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Y.B.S.); (U.B.K.)
- Division of Research Center, Scripps Korea Antibody Institute, Chuncheon 24341, Korea
| | - Zulfiah Mohamed-Moosa
- Centre for Neuroendocrinology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa; (S.H.); (Z.M.-M.); (I.v.d.B.); (A.C.S.); (R.P.M.); (C.L.N.)
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa
- Department of Anatomy and Physiology, Faculty of Veterinary Sciences, University of Pretoria, Private Bag X04, Pretoria 0110, South Africa
| | - Iman van den Bout
- Centre for Neuroendocrinology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa; (S.H.); (Z.M.-M.); (I.v.d.B.); (A.C.S.); (R.P.M.); (C.L.N.)
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa
| | - Alexis C. Schwulst
- Centre for Neuroendocrinology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa; (S.H.); (Z.M.-M.); (I.v.d.B.); (A.C.S.); (R.P.M.); (C.L.N.)
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa
| | - Ursula B. Kaiser
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA; (Y.B.S.); (U.B.K.)
| | - Robert P. Millar
- Centre for Neuroendocrinology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa; (S.H.); (Z.M.-M.); (I.v.d.B.); (A.C.S.); (R.P.M.); (C.L.N.)
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa
- Department of Integrative Biomedical Sciences, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Observatory 7925, South Africa
- Deanery of Biomedical Sciences, University of Edinburgh, Edinburgh EH8 9JZ, UK
- School of Medicine, Medical and Biological Sciences Building, University of St Andrews, St Andrews KY16 9TF, UK
| | - Claire L. Newton
- Centre for Neuroendocrinology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa; (S.H.); (Z.M.-M.); (I.v.d.B.); (A.C.S.); (R.P.M.); (C.L.N.)
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Pretoria 0031, South Africa
- Deanery of Biomedical Sciences, University of Edinburgh, Edinburgh EH8 9JZ, UK
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Ellero AA, van den Bout I, Vlok M, Cromarty AD, Hurrell T. Continual proteomic divergence of HepG2 cells as a consequence of long-term spheroid culture. Sci Rep 2021; 11:10917. [PMID: 34035320 PMCID: PMC8149451 DOI: 10.1038/s41598-021-89907-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 04/28/2021] [Indexed: 02/04/2023] Open
Abstract
Three-dimensional models are considered a powerful tool for improving the concordance between in vitro and in vivo phenotypes. However, the duration of spheroid culture may influence the degree of correlation between these counterparts. When using immortalised cell lines as model systems, the assumption for consistency and reproducibility is often made without adequate characterization or validation. It is therefore essential to define the biology of each spheroid model by investigating proteomic dynamics, which may be altered relative to culture duration. As an example, we assessed the influence of culture duration on the relative proteome abundance of HepG2 cells cultured as spheroids, which are routinely used to model aspects of the liver. Quantitative proteomic profiling of whole cell lysates labelled with tandem-mass tags was conducted using liquid chromatography-tandem mass spectrometry (LC-MS/MS). In excess of 4800 proteins were confidently identified, which were shared across three consecutive time points over 28 days. The HepG2 spheroid proteome was divergent from the monolayer proteome after 14 days in culture and continued to change over the successive culture time points. Proteins representing the recognised core hepatic proteome, cell junction, extracellular matrix, and cell adhesion proteins were found to be continually modulated.
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Affiliation(s)
- Andrea Antonio Ellero
- grid.49697.350000 0001 2107 2298Department of Pharmacology, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa ,grid.49697.350000 0001 2107 2298Centre for Neuroendocrinology, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa
| | - Iman van den Bout
- grid.49697.350000 0001 2107 2298Centre for Neuroendocrinology, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa ,grid.49697.350000 0001 2107 2298Department of Physiology, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa
| | - Maré Vlok
- grid.11956.3a0000 0001 2214 904XProteomics Unit, Central Analytical Facility, Stellenbosch University, Stellenbosch, South Africa
| | - Allan Duncan Cromarty
- grid.49697.350000 0001 2107 2298Department of Pharmacology, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa
| | - Tracey Hurrell
- grid.7327.10000 0004 0607 1766Bioengineering and Integrated Genomics Group, Next Generation Health Cluster, Council for Scientific and Industrial Research, Pretoria, South Africa
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van Vuuren RJ, Botes M, Jurgens T, Joubert AM, van den Bout I. Correction to: Novel sulphamoylated 2-methoxy estradiol derivatives inhibit breast cancer migration by disrupting microtubule turnover and organization. Cancer Cell Int 2020; 20:308. [PMID: 32684845 PMCID: PMC7359456 DOI: 10.1186/s12935-020-01408-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Affiliation(s)
| | - Mandie Botes
- Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa.,Centre for Neuroendocrinology, University of Pretoria, Pretoria, 0084 South Africa
| | - Tamarin Jurgens
- Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa
| | | | - Iman van den Bout
- Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa.,Centre for Neuroendocrinology, University of Pretoria, Pretoria, 0084 South Africa
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van Vuuren RJ, Botes M, Jurgens T, Joubert AM, van den Bout I. Novel sulphamoylated 2-methoxy estradiol derivatives inhibit breast cancer migration by disrupting microtubule turnover and organization. Cancer Cell Int 2019; 19:1. [PMID: 30622437 PMCID: PMC6317210 DOI: 10.1186/s12935-018-0719-4] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 12/21/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The estrogen metabolite 2-methoxyestradiol (2ME2) and a number of synthesised derivatives have been shown to bind to microtubules thereby arresting cancer cells in mitosis which leads to apoptosis. In interphase cells, microtubules play an important role in the delivery of proteins to subcellular locations including the focal adhesions. In fact, focal adhesion dynamics and cell migration are in part regulated by microtubules. We hypothesised that novel 2ME2 derivatives can alter cell migration by influencing microtubule dynamics in interphase cells. In this report we describe 2ME2 derivatives that display anti-migratory capabilities in a metastatic breast cancer cell line through their effects on the microtubule network resulting in altered focal adhesion signalling and RhoA activity. METHODS Cell migration was assayed using wound healing assays. To eliminate mitosis blockage and cell rounding as a confounding factor cell migration was also assessed in interphase blocked cells. Fluorescence confocal microscopy was used to visualise microtubule dynamics and actin cytoskeleton organisation while western blot analysis was performed to analyse focal adhesion signalling and RhoA activation. RESULTS 2ME2 derivatives, ESE-one and ESE-15-one, inhibited cell migration in cycling cells as expected but equally diminished migration in cells blocked in interphase. While no significant effects were observed on the actin cytoskeleton, focal adhesion kinase activity was increased while RhoA GTPase activity was inhibited after exposure to either compound. Microtubule stability was increased as evidenced by the increased length and number of detyrosinated microtubules while at the same time clear disorganisation of the normal radial microtubule organisation was observed including multiple foci. CONCLUSIONS ESE-15-one and ESE-one are potent migration inhibitors of metastatic breast cancer cells. This ability is coupled to alterations in focal adhesion signalling but more importantly is associated with severe disorganisation of microtubule dynamics and polarity. Therefore, these compounds may offer potential as anti-metastatic therapies.
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Affiliation(s)
| | - Mandie Botes
- Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa
- Centre for Neuroendocrinology, University of Pretoria, Pretoria, 0084 South Africa
| | - Tamarin Jurgens
- Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa
| | | | - Iman van den Bout
- Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa
- Centre for Neuroendocrinology, University of Pretoria, Pretoria, 0084 South Africa
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Botes M, Jurgens T, Riahi Z, Visagie M, Janse van Vuuren R, Joubert AM, van den Bout I. A novel non-sulphamoylated 2-methoxyestradiol derivative causes detachment of breast cancer cells by rapid disassembly of focal adhesions. Cancer Cell Int 2018; 18:188. [PMID: 30479567 PMCID: PMC6245879 DOI: 10.1186/s12935-018-0688-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/13/2018] [Indexed: 12/14/2022] Open
Abstract
Background 2-Methoxyestradiol (2ME2) is an estradiol metabolite with well documented antiproliferative properties in many cancer cell lines. However, it is rapidly metabolised in vivo which limits its clinical application. Therefore, more stable derivatives with potentially improved clinical features have been designed by our group. Here we describe an estrone-like derivative of 2ME2, namely EE-15-one, that unlike other derivatives which induce cell cycle arrest, induces a rapid loss of cell–substrate adhesion through the inactivation and disassembly of focal adhesions. Methods To assess the effect of 2-ethyl-estra-1,3,5 (10),15-tetraen-3-ol-17-one (EE-15-one) on breast cancer cell lines, cell survival was quantified. The effect of EE-15-one on cell attachment was assessed by measuring cell adhesion and cell rounding via light microscopy. Effects on focal adhesion dynamics and actin cytoskeleton organisation were visualised by immunofluorescence while focal adhesion signalling was assessed by western blot. Cell death was quantified using a lactate dehydrogenase activity (LDH) assay. To investigate specificity towards cell–substrate over cell–cell contact inhibition, EE-15-one effects on 3D cell cultures were assessed. Results Cell survival assays show an almost complete loss of cells within 24 h of EE-15-one exposure in contrast to published sulphamoylated 2ME2 derivatives. Cell loss is linked to rapid detachment and adhesion inhibition. Focal adhesion size and number are rapidly diminished while actin fibres became severed and disappeared within 2 h post exposure. These changes were not due to cell necrosis as LDH activity only slightly increased after 24 h. Cells grown in cell–cell adhesion dependent spheroids did not respond to EE-15-one exposure suggesting that EE-15-one specifically inhibits cell–substrate adhesions but not cell–cell adhesions and does not directly impact the actin cytoskeleton. Conclusion We show that a novel 2ME2 derivative, EE-15-one, induces rapid loss of focal adhesion function leading to cell–substrate detachment through interference with integrin-based cell–substrate adhesions, but not cadherin dependent cell–cell adhesions. Therefore, EE-15-one is the first 2ME2 derivative that has an alternative mode of action to the antimitotic activity of 2ME2. As such EE-15-one shows potential as a lead compound for further development as an inhibitor of cell–substrate adhesion which is essential for metastatic dissemination. Electronic supplementary material The online version of this article (10.1186/s12935-018-0688-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mandie Botes
- 1Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa.,2Centre for Neuroendocrinology, University of Pretoria, Pretoria, 0084 South Africa
| | - Tamarin Jurgens
- 1Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa.,2Centre for Neuroendocrinology, University of Pretoria, Pretoria, 0084 South Africa
| | - Zohreh Riahi
- 1Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa
| | - Michelle Visagie
- 1Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa
| | | | | | - Iman van den Bout
- 1Department of Physiology, University of Pretoria, Pretoria, 0084 South Africa.,2Centre for Neuroendocrinology, University of Pretoria, Pretoria, 0084 South Africa
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Nkandeu SD, van den Bout I, Cronjé MJ, van Papendorp DH, Joubert AM. A Novel 2-Methoxyestradiol Analogue Is Responsible for Vesicle Disruption and Lysosome Aggregation in Breast Cancer Cells. Pharmacology 2018; 102:9-16. [PMID: 29672318 DOI: 10.1159/000487443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 01/30/2018] [Indexed: 11/19/2022]
Abstract
BACKGROUND 2-Methoxyestradiol (2ME2) is an endogenous metabolite of 17-β-estradiol with anti-proliferative and anti-angiogenic properties. Due to 2ME2's rapid metabolism and low oral bioavailability in in vivo settings, 2ME2 analogues have been designed to alleviate these issues. One of these compounds is 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene (ESE-16). A previous work alluded to the ability of ESE-16 to induce autophagic cell death. Therefore, we investigated the mode of action of ESE-16 by studying its effects on autophagy, vesicle formation, and lysosomal organisation. SUMMARY Vesicle formation and autophagy induction were analysed by transmission electron microscopy (TEM), monodansylcadaverine (MDC) staining and Lysotracker staining, while autophagosome turnover was analysed using microtubule-associated protein 1A/1B-light chain 3 (LC3 lipidation) analysis. MDC staining of acidic vesicles revealed an increase both in the number and size of vesicles after ESE-16 exposure. This was confirmed by TEM. Lysotracker staining indicated an increase in the size of lysosomes, as well as changes in their distribution within the cell. However, autophagy was not induced, since LC3 lipidation did not increase after exposure to ESE-16. Key -Messages: This study showed that ESE-16 exposure leads to the aggregation of acidic vesicles, identified as lysosomes, not accompanied by an induction of autophagy. Therefore, ESE-16 disrupts normal endocytic vesicle maturation likely through the inhibition of the microtubule function.
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Affiliation(s)
- Sandra D Nkandeu
- Department of Physiology, University of Pretoria, Pretoria, South Africa
| | - Iman van den Bout
- Department of Physiology, University of Pretoria, Pretoria, South Africa.,Centre for Neuroendocrinology, University of Pretoria, Pretoria, South Africa
| | - Marianne J Cronjé
- Department of Biochemistry, University of Johannesburg, Johannesburg, South Africa
| | | | - Anna M Joubert
- Department of Physiology, University of Pretoria, Pretoria, South Africa
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11
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Visagie MH, van den Bout I, Joubert AM. A bis-sulphamoylated estradiol derivative induces ROS-dependent cell cycle abnormalities and subsequent apoptosis. PLoS One 2017; 12:e0176006. [PMID: 28410397 PMCID: PMC5391954 DOI: 10.1371/journal.pone.0176006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [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: 08/02/2016] [Accepted: 03/27/2017] [Indexed: 01/23/2023] Open
Abstract
Clinical trials have revealed that the potential anticancer agent, 2-methoxyestradiol (2ME2) has limitations due to its low bioavailability. Subsequently, 2ME2 derivatives including (8R,13S,14S,17S)-2-ethyl-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrane-3,17-diyl bis(sulphamate) (EMBS) have shown improved efficacies in inducing apoptosis. However, no conclusive data exist to explain the mode of action exerted by these drugs. This study investigated the mode of action used by EMBS as a representative of the sulphamoylated 2ME2 derivatives. Hydrogen peroxide and superoxide production was quantified using dichlorofluorescein diacetate and hydroethidine. Cell proliferation and mitochondrial metabolism were investigated using crystal violet and Alamar Blue. Apoptosis was assessed using Annexin V-FITC while mitochondrial integrity was assessed using Mitocapture. Autophagy was visualised using LC3B II antibodies. The effects of EMBS on H2A phosphorylation and nuclei were visualised using phospho H2A antibody and 4',6-diamidino-2-phenylindole, dihydrochloride. Data showed that EMBS exposure leads to increased reactive oxygen species (ROS) production which is correlated with loss of cell proliferation, mitochondrial membrane damage, decreased metabolic activity, G2/M arrest, endoreduplication, DNA double stranded breaks, micronuclei and apoptosis induction. Treatment of EMBS-exposed cells with the ROS scavenger, N-acetyl cysteine, abrogated ROS production, cell cycle arrest and apoptosis implying an essential role for ROS production in EMBS signaling. The inhibition of c-Jun N-terminal kinase (JNK) activity also inhibited EMBS-induced apoptosis suggesting that EMBS triggers apoptosis via the JNK pathway. Lastly, evaluation of LC3IIB protein levels indicated that autophagy is not activated in EMBS-exposed cells. Our data shows that EMBS targets a pathway that leads to increased ROS production as an early event that culminates in G2/M arrest and apoptosis by means of JNK-signaling in cancer cells. This study suggests a novel oxidative stress-dependent mode of action for sulphamoylated derivatives.
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Affiliation(s)
- Michelle Helen Visagie
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, Gauteng, South Africa
- * E-mail:
| | - Iman van den Bout
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, Gauteng, South Africa
| | - Anna Margaretha Joubert
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, Gauteng, South Africa
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12
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Visuttijai K, Pettersson J, Mehrbani Azar Y, van den Bout I, Örndal C, Marcickiewicz J, Nilsson S, Hörnquist M, Olsson B, Ejeskär K, Behboudi A. Lowered Expression of Tumor Suppressor Candidate MYO1C Stimulates Cell Proliferation, Suppresses Cell Adhesion and Activates AKT. PLoS One 2016; 11:e0164063. [PMID: 27716847 PMCID: PMC5055341 DOI: 10.1371/journal.pone.0164063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 09/18/2016] [Indexed: 12/12/2022] Open
Abstract
Myosin-1C (MYO1C) is a tumor suppressor candidate located in a region of recurrent losses distal to TP53. Myo1c can tightly and specifically bind to PIP2, the substrate of Phosphoinositide 3-kinase (PI3K), and to Rictor, suggesting a role for MYO1C in the PI3K pathway. This study was designed to examine MYO1C expression status in a panel of well-stratified endometrial carcinomas as well as to assess the biological significance of MYO1C as a tumor suppressor in vitro. We found a significant correlation between the tumor stage and lowered expression of MYO1C in endometrial carcinoma samples. In cell transfection experiments, we found a negative correlation between MYO1C expression and cell proliferation, and MYO1C silencing resulted in diminished cell migration and adhesion. Cells expressing excess of MYO1C had low basal level of phosphorylated protein kinase B (PKB, a.k.a. AKT) and cells with knocked down MYO1C expression showed a quicker phosphorylated AKT (pAKT) response in reaction to serum stimulation. Taken together the present study gives further evidence for tumor suppressor activity of MYO1C and suggests MYO1C mediates its tumor suppressor function through inhibition of PI3K pathway and its involvement in loss of contact inhibition.
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Affiliation(s)
- Kittichate Visuttijai
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
- Department of Medical and Clinical Genetics, Sahlgrenska Academy, University of Gothenburg, SE-405 30, Gothenburg, Sweden
| | - Jennifer Pettersson
- Department of Medical and Clinical Genetics, Sahlgrenska Academy, University of Gothenburg, SE-405 30, Gothenburg, Sweden
| | - Yashar Mehrbani Azar
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
| | - Iman van den Bout
- Department of physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, 0007, South Africa
| | - Charlotte Örndal
- Department of Pathology, Sahlgrenska University Hospital, SE-413 45, Gothenburg, Sweden
| | - Janusz Marcickiewicz
- Department of Obstetrics and Gynecology, Halland Hospital Varberg, SE- 432 37, Varberg, Sweden
| | - Staffan Nilsson
- Institute of Mathematical Statistics, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Michael Hörnquist
- Department of Science and Technology, University of Linköping, ITN, SE-601 74, Norrköping, Sweden
| | - Björn Olsson
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
| | - Katarina Ejeskär
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
| | - Afrouz Behboudi
- School of Bioscience, Tumor Biology research group, University of Skövde, SE-541 28, Skövde, Sweden
- * E-mail:
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13
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Theron A, Prudent R, Nolte E, van den Bout I, Punchoo R, Marais S, du Toit P, Hlophe Y, van Papendorp D, Lafanechère L, Joubert A. Novel in silico-designed estradiol analogues are cytotoxic to a multidrug-resistant cell line at nanomolar concentrations. Cancer Chemother Pharmacol 2014; 75:431-7. [PMID: 25547405 DOI: 10.1007/s00280-014-2653-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 12/15/2014] [Indexed: 01/10/2023]
Abstract
PURPOSE 2-Methoxyestradiol (2ME) is a promising anti-cancer agent that disrupts the integrity and dynamics of the spindle network. In order to overcome the pharmacokinetic constraints of this compound, a panel of sulphamoylated estradiol analogues were in silico-designed by our laboratory. In this study, we analysed the potential of each analogue to induce cell death on a panel of cancer cell lines. Moreover, the mechanism of action of the most effective compounds was determined. METHODS Cytotoxicity screening of the compounds and intermediates was performed on five different cancer cell lines to determine IG50 values. An in vitro tubulin polymerization assay was done to determine the effect of the drugs on tubulin polymerization while their intracellular effects on the microtubule network were assessed by immunofluorescence microscopy. RESULTS IG50 calculations showed that the sulphamoylated analogues induce cytotoxicity at nanomolar concentrations in all cell lines, including the P-glycoprotein pump overexpressing multidrug-resistant uterine sarcoma cell line. The non-sulphamoylated compounds were only cytotoxic at micromolar ranges, if at all. The sulphamoylated compounds inhibited pure tubulin polymerization in a dose-dependent manner and induced microtubule destruction in cells after 24-h exposure. CONCLUSION Results revealed that the novel sulphamoylated 2ME derivatives have potential as anti-cancer drugs, possibly even against chemoresistant cancer cells. These compounds disrupt the intracellular microtubule integrity which leads to mitotic block of the cells.
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Affiliation(s)
- Anne Theron
- Department of Physiology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, Pretoria, Gauteng, 0007, South Africa,
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14
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Margadant C, van den Bout I, van Boxtel AL, Thijssen VL, Sonnenberg A. Epigenetic regulation of galectin-3 expression by β1 integrins promotes cell adhesion and migration. J Biol Chem 2012; 287:44684-93. [PMID: 23118221 DOI: 10.1074/jbc.m112.426445] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Introduction of the integrin β1- but not the β3-subunit in GE11 cells induces an epithelial-to-mesenchymal-transition (EMT)-like phenomenon that is characterized by the loss of cell-cell contacts, cell scattering, increased cell migration and RhoA activity, and fibronectin fibrillogenesis. Because galactose-binding lectins (galectins) have been implicated in these phenomena, we investigated whether galectins are involved in the β1-induced phenotype. We examined 9 galectins and, intriguingly, found that the expression of galectin-3 (Gal-3) is specifically induced by β1 but not by β3. Using β1-β3 chimeric integrins, we show that the induction of Gal-3 expression requires the hypervariable region in the extracellular domain of β1, but not its cytoplasmic tail. Furthermore, Gal-3 expression does not depend on RhoA signaling, serum factors, or any of the major signal transduction pathways involving protein kinase C (PKC), p38 mitogen-activated protein kinase (p38MAPK), extracellular signal-regulated kinase-1/-2 (ERK-1/2), phosphatidylinositol-3-OH kinase (PI3-K), or Src kinases. Instead, Gal-3 expression is controlled in an epigenetic manner. Whereas DNA methylation of the Lgals3 promoter maintains Gal-3 silencing in GE11 cells, expression of β1 causes its demethylation, leading to transcriptional activation of the Lgals3 gene. In turn, Gal-3 expression enhances β1 integrin-mediated cell adhesion to fibronectin (FN) and laminin (LN), as well as cell migration. Gal-3 also promotes β1-mediated cell adhesion to LN and Collagen-1 (Col)-1 in cells that endogenously express Gal-3 and β1 integrins. In conclusion, we identify a functional feedback-loop between β1 integrins and Gal-3 that involves the epigenetic induction of Gal-3 expression during integrin-induced EMT and cell scattering.
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Affiliation(s)
- Coert Margadant
- Division of Cell Biology, the Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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15
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Halstead JR, Savaskan NE, van den Bout I, Van Horck F, Hajdo-Milasinovic A, Snell M, Keune WJ, ten Klooster JP, Hordijk PL, Divecha N. Rac controls PIP5K localisation and PtdIns(4,5)P2 synthesis, which modulates vinculin localisation and neurite dynamics. J Cell Sci 2010; 123:3535-46. [DOI: 10.1242/jcs.062679] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In N1E-115 cells, neurite retraction induced by neurite remodelling factors such as lysophosphatidic acid, sphingosine 1-phosphate and semaphorin 3A require the activity of phosphatidylinositol 4-phosphate 5-kinases (PIP5Ks). PIP5Ks synthesise the phosphoinositide lipid second messenger phosphatidylinositol(4,5)bisphosphate [PtdIns(4,5)P2], and overexpression of active PIP5K is sufficient to induce neurite retraction in both N1E-115 cells and cerebellar granule neurones. However, how PIP5Ks are regulated or how they induce neurite retraction is not well defined. Here, we show that neurite retraction induced by PIP5Kβ is dependent on its interaction with the low molecular weight G protein Rac. We identified the interaction site between PIP5Kβ and Rac1 and generated a point mutant of PIP5Kβ that no longer interacts with endogenous Rac. Using this mutant, we show that Rac controls the plasma membrane localisation of PIP5Kβ and thereby the localised synthesis of PtdIns(4,5)P2 required to induce neurite retraction. Mutation of this residue in other PIP5K isoforms also attenuates their ability to induce neurite retraction and to localise at the membrane. To clarify how increased levels of PtdIns(4,5)P2 induce neurite retraction, we show that mutants of vinculin that are unable to interact with PtdIns(4,5)P2, attenuate PIP5K- and LPA-induced neurite retraction. Our findings support a role for PtdIns(4,5)P2 synthesis in the regulation of vinculin localisation at focal complexes and ultimately in the regulation of neurite dynamics.
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Affiliation(s)
- Jonathan R. Halstead
- Division of Cell Biology, The Netherlands Cancer Institute Amsterdam, Amsterdam, 1066 CX, The Netherlands
| | - Nicolai E. Savaskan
- Division of Cell Biology, The Netherlands Cancer Institute Amsterdam, Amsterdam, 1066 CX, The Netherlands
- Institute of Cell Biology and Neurobiology, Charité – Universitätsmedizin Berlin, D-10115 Berlin, Germany
| | - Iman van den Bout
- The CRUK Inositide Laboratory, The Paterson Institute for Cancer Research, Wilmslow Road, Manchester M20 4BX, UK
| | - Francis Van Horck
- Department of Physiology, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - Amra Hajdo-Milasinovic
- Division of Cell Biology, The Netherlands Cancer Institute Amsterdam, Amsterdam, 1066 CX, The Netherlands
| | - Mireille Snell
- Division of Cell Biology, The Netherlands Cancer Institute Amsterdam, Amsterdam, 1066 CX, The Netherlands
| | - Willem-Jan Keune
- Division of Cell Biology, The Netherlands Cancer Institute Amsterdam, Amsterdam, 1066 CX, The Netherlands
- The CRUK Inositide Laboratory, The Paterson Institute for Cancer Research, Wilmslow Road, Manchester M20 4BX, UK
| | - Jean-Paul ten Klooster
- Sanquin Research at CLB and Landsteiner Laboratory, Academic Medical Centre, University of Amsterdam, Amsterdam, 1066 CX, The Netherlands
| | - Peter L. Hordijk
- Sanquin Research at CLB and Landsteiner Laboratory, Academic Medical Centre, University of Amsterdam, Amsterdam, 1066 CX, The Netherlands
| | - Nullin Divecha
- Division of Cell Biology, The Netherlands Cancer Institute Amsterdam, Amsterdam, 1066 CX, The Netherlands
- The CRUK Inositide Laboratory, The Paterson Institute for Cancer Research, Wilmslow Road, Manchester M20 4BX, UK
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Abstract
It has long been known that phosphoinositides are present in cellular membranes, but only in the past four decades has our understanding of their importance for proper cell function advanced significantly. Key to determining the biological roles of phosphoinositides is understanding the enzymes involved in their metabolism. Although many such enzymes have now been identified, there is still much to learn about their cellular functions. Phosphatidylinositol 4-phosphate 5-kinases (PIP5Ks) are a group of kinases that catalyse the production of phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P2]. As well as being a substrate for the enzymes phospholipase C (PLC) and phosphatidylinositol 3-kinase (PI3K), PtdIns(4,5)P2 acts as a second messenger in its own right, influencing a variety of cellular processes. In this Commentary, we review how PIP5Ks are modulated to achieve regulated PtdIns(4,5)P2 production, and discuss the role of these proteins in different cellular processes.
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Affiliation(s)
- Iman van den Bout
- Inositide Laboratory, Paterson Institute for Cancer Research, Wilmslow Road, Manchester M20 4BX, UK
| | - Nullin Divecha
- Inositide Laboratory, Paterson Institute for Cancer Research, Wilmslow Road, Manchester M20 4BX, UK
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17
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van den Bout I, van Rheenen J, van Angelen AA, de Rooij J, Wilhelmsen K, Jalink K, Divecha N, Sonnenberg A. Investigation into the mechanism regulating MRP localization. Exp Cell Res 2007; 314:330-41. [PMID: 17897642 DOI: 10.1016/j.yexcr.2007.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Revised: 08/21/2007] [Accepted: 08/23/2007] [Indexed: 11/15/2022]
Abstract
The major PKC substrates MARCKS and MacMARCKS (MRP) are membrane-binding proteins implicated in cell spreading, integrin activation and exocytosis. According to the myristoyl-electrostatic switch model the co-operation between the myristoyl moiety and the positively charged effector domain (ED) is an essential mechanism by which proteins bind to membranes. Loss of the electrostatic interaction between the ED and phospholipids, such as Ptdins(4,5)P2, results in the translocation of such proteins to the cytoplasm. While this model has been extensively tested for the binding of MARCKS far less is known about the mechanisms regulating MRP localization. We demonstrate that after phosphorylation, MRP is relocated to the intracellular membranes of late endosomes and lysosomes. MRP binds to all membranes via its myristoyl moiety, but for its localization at the plasma membrane the ED is also required. Although the ED of MRP can bind to Ptdins(4,5)P2 in vitro, this binding is not essential for its retention at or targeting to the plasma membrane. We conclude that the co-operation between the myristoyl moiety and the ED is not required for the binding to membranes in general but that it is essential for the targeting of MRP to the plasma membrane in a Ptdins(4,5)P2-independent manner.
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Affiliation(s)
- Iman van den Bout
- Division of Cell Biology, Netherlands Cancer Institute, 121 Plesmanlaan, 1066 CX Amsterdam, The Netherlands
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18
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van den Bout I, Truong HH, Huveneers S, Kuikman I, Danen EHJ, Sonnenberg A. The regulation of MacMARCKS expression by integrin β3. Exp Cell Res 2007; 313:1260-9. [PMID: 17292354 DOI: 10.1016/j.yexcr.2007.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 12/13/2006] [Accepted: 01/04/2007] [Indexed: 01/09/2023]
Abstract
Integrin-mediated adhesion regulates multiple signaling pathways. Our group previously showed that ectopic expression of different integrin beta-subunits in the neuroepithelial cell line GE11, has distinct effects on cell morphology, actin cytoskeletal organization, and on focal contact distribution. In this report we have investigated changes in gene transcription levels resulting from overexpression of the integrin beta3 subunit. We found that beta3 overexpression leads to the transcriptional downregulation of MARCKS related protein (MRP) resulting in a decreased expression of the MRP protein. Furthermore, we show that the Ras/MAPK pathway controls the basal level of MRP expression but beta3 overexpression bypasses this pathway downstream of ERK to downregulate MRP. Further studies indicate that a region of the cytoplasmic tail of beta3 containing part of the NITY motif is responsible for increased cell spreading and MRP downregulation. However, MRP overexpression failed to inhibit the beta3-induced increase in cell spreading while the knock down of MRP expression in GE11 cells did not increase cell spreading. We suggest that the downregulation of MRP by beta3 is not required for increased cell spreading but instead that MRP downregulation is a secondary effect of increased cell spreading.
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Affiliation(s)
- Iman van den Bout
- Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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19
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Abstract
Increased activity of the proto-oncogene c-Src and elevated levels of integrin alpha(v)beta(3) are found in melanomas and multiple carcinomas. Regulation of c-Src involves "priming" through disruption of intramolecular interactions followed by "activation" through phosphorylation in the kinase domain. Interactions with overexpressed receptor tyrosine kinases or mutations in the SRC gene can induce priming of c-Src in cancer. Here, we show that alpha(v)beta(3) promotes activation of primed c-Src, causing enhanced phosphorylation of established Src substrates, survival, proliferation, and tumor growth. The beta(3) cytoplasmic tail is required and sufficient for integrin-mediated stimulation of all these events through a mechanism that is independent of beta(3) tyrosine phosphorylation. Instead, experiments using Src variants containing the v-Src Src homology 3 (SH3) domain and using mutant beta(3) subunits indicate that a functional interaction of the beta(3) cytoplasmic tail with the c-Src SH3 domain is required. These findings delineate a novel integrin-controlled oncogenic signaling cascade and suggest that the interaction of alpha(v)beta(3) with c-Src may represent a novel target for therapeutic intervention.
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Affiliation(s)
- Stephan Huveneers
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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Wilhelmsen K, Litjens SHM, Kuikman I, Tshimbalanga N, Janssen H, van den Bout I, Raymond K, Sonnenberg A. Nesprin-3, a novel outer nuclear membrane protein, associates with the cytoskeletal linker protein plectin. ACTA ACUST UNITED AC 2006; 171:799-810. [PMID: 16330710 PMCID: PMC2171291 DOI: 10.1083/jcb.200506083] [Citation(s) in RCA: 360] [Impact Index Per Article: 20.0] [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] [Indexed: 12/04/2022]
Abstract
Despite their importance in cell biology, the mechanisms that maintain the nucleus in its proper position in the cell are not well understood. This is primarily the result of an incomplete knowledge of the proteins in the outer nuclear membrane (ONM) that are able to associate with the different cytoskeletal systems. Two related ONM proteins, nuclear envelope spectrin repeat (nesprin)–1 and –2, are known to make direct connections with the actin cytoskeleton through their NH2-terminal actin-binding domain (ABD). We have now isolated a third member of the nesprin family that lacks an ABD and instead binds to the plakin family member plectin, which can associate with the intermediate filament (IF) system. Overexpression of nesprin-3 results in a dramatic recruitment of plectin to the nuclear perimeter, which is where these two molecules are colocalized with both keratin-6 and -14. Importantly, plectin binds to the integrin α6β4 at the cell surface and to nesprin-3 at the ONM in keratinocytes, suggesting that there is a continuous connection between the nucleus and the extracellular matrix through the IF cytoskeleton.
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Affiliation(s)
- Kevin Wilhelmsen
- Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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