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Caberoy NB, Maiguel D, Kim Y, Li W. Identification of tubby and tubby-like protein 1 as eat-me signals by phage display. Exp Cell Res 2009; 316:245-57. [PMID: 19837063 DOI: 10.1016/j.yexcr.2009.10.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 09/10/2009] [Accepted: 10/07/2009] [Indexed: 01/24/2023]
Abstract
Phagocytosis is an important process for the removal of apoptotic cells or cellular debris. Eat-me signals control the initiation of phagocytosis and hold the key for in-depth understanding of its molecular mechanisms. However, because of difficulties to identify unknown eat-me signals, only a limited number of them have been identified and characterized. Using a newly developed functional cloning strategy of open reading frame (ORF) phage display, we identified nine putative eat-me signals, including tubby-like protein 1 (Tulp1). This further led to the elucidation of tubby as the second eat-me signal in the same protein family. Both proteins stimulated phagocytosis of retinal pigment epithelium (RPE) cells and macrophages. Tubby-conjugated fluorescent microbeads facilitated RPE phagocytosis. Tubby and Tulp1, but not other family members, enhanced the uptake of membrane vesicles by RPE cells in synergy. Retinal membrane vesicles of Tubby mice and Tulp1(-/-) mice showed reduced activities for RPE phagocytosis, which were compensated by purified tubby and Tulp1, respectively. These data reveal a novel activity of tubby and Tulp1, and demonstrate that unbiased identification of eat-me signals by the broadly applicable strategy of ORF phage display can provide detailed insights into phagocyte biology.
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Affiliation(s)
- Nora B Caberoy
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, 1638 NW 10th Avenue, Miami, FL 33136, USA
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Gene delivery targeted to the brain using an Angiopep-conjugated polyethyleneglycol-modified polyamidoamine dendrimer. Biomaterials 2009; 30:6976-85. [PMID: 19765819 DOI: 10.1016/j.biomaterials.2009.08.049] [Citation(s) in RCA: 224] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 08/28/2009] [Indexed: 01/12/2023]
Abstract
Angiopep targeting to the low-density lipoprotein receptor-related protein-1 (LRP1) was identified to exhibit high transcytosis capacity and parenchymal accumulation. In this study, it was exploited as a ligand for effective brain-targeting gene delivery. Polyamidoamine dendrimers (PAMAM) were modified with angiopep through bifunctional PEG, then complexed with DNA, yielding PAMAM-PEG-Angiopep/DNA nanoparticles (NPs). The angiopep-modified NPs were observed to be internalized by brain capillary endothelial cells (BCECs) through a clathrin- and caveolae-mediated energy-depending endocytosis, also partly through marcopinocytosis. Also, the cellular uptake of the angiopep-modified NPs were competed by angiopep-2, receptor-associated protein (RAP) and lactoferrin, indicating that LRP1-mediated endocytosis may be the main mechanism of cellular internalization of angiopep-modified NPs. And the angiopep-modified NPs showed higher efficiency in crossing blood-brain barrier (BBB) than unmodified NPs in an in vitro BBB model, and accumulated in brain more in vivo. The angiopep-modified NPs also showed higher efficiency in gene expressing in brain than the unmodified NPs. In conclusion, PAMAM-PEG-Angiopep showed great potential to be applied in designing brain-targeting drug delivery system.
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Caberoy NB, Zhou Y, Li W. Can phage display be used as a tool to functionally identify endogenous eat-me signals in phagocytosis? ACTA ACUST UNITED AC 2009; 14:653-61. [PMID: 19531662 DOI: 10.1177/1087057109335679] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Removal of apoptotic cells and cellular debris by phagocytosis is essential for development, tissue homeostasis, and resolution of inflammation. Eat-me signals control the initiation of phagocytosis, holding a key to the understanding of phagocyte biology. Because of a lack of functional cloning strategy, eat-me signals are conventionally identified and characterized on a case-by-case basis. The feasibility of functional cloning of eat-me signals by phage display is investigated by characterizing the biological behavior of T7 phages displaying 2 well-known eat-me signals: growth arrest-specific gene 6 (Gas6) and milk fat globule-EGF8 (MFG-E8). Gas6-phage binds to all 3 known Gas6 receptors: Mer, Axl, and Tyro3 receptor tyrosine kinases. Gas6-phage and MFG-E8-phage are capable of binding to phagocytes and nonphagocytes. However, both phages stimulate phage uptake only in phagocytes, including macrophages, microglia, and retinal pigment epithelium cells, but not in nonphagocytes. Furthermore, functional phage selection by phagocytosis in phagocytes enriches both Gas6-phage and MFG-E8-phage, suggesting that phage display can be used as a tool to functionally identify unknown eat-me signals from phage display cDNA library.
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Affiliation(s)
- Nora B Caberoy
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami School of Medicine, Miami, Florida 33136, USA
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Jayakumar A, Widenmaier R, Ma X, McDowell MA. Transcriptional inhibition of interleukin-12 promoter activity in Leishmania spp.-infected macrophages. J Parasitol 2008; 94:84-93. [PMID: 18372625 DOI: 10.1645/ge-1153.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
To establish and persist within a host, Leishmania spp. parasites delay the onset of cell-mediated immunity by suppressing interleukin-12 (IL-12) production from host macrophages. Although it is established that Leishmania spp.-infected macrophages have impaired IL-12 production, the mechanisms that account for this suppression remain to be completely elucidated. Using a luciferase reporter assay assessing IL-12 transcription, we report here that Leishmania major, Leishmania donovani, and Leishmania chagasi inhibit IL-12 transcription in response to interferon-gamma, lipopolysaccharide, and CD40 ligand and that Leishmania spp. lipophosphoglycan, phosphoglycans, and major surface protein are not necessary for inhibition. In addition, all the Leishmania spp. strains and life-cycle stages tested inhibited IL-12 promoter activity. Our data further reveal that autocrine-acting host factors play no role in the inhibitory response and that phagocytosis signaling is necessary for inhibition of IL-12.
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Affiliation(s)
- Asha Jayakumar
- 215 Galvin Life Sciences, Center for Global Health and Infectious Diseases, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Oesterling E, Chopra N, Gavalas V, Arzuaga X, Lim EJ, Sultana R, Butterfield DA, Bachas L, Hennig B. Alumina nanoparticles induce expression of endothelial cell adhesion molecules. Toxicol Lett 2008; 178:160-6. [PMID: 18456438 DOI: 10.1016/j.toxlet.2008.03.011] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 03/12/2008] [Accepted: 03/12/2008] [Indexed: 01/09/2023]
Abstract
Nanotechnology is a rapidly growing industry that has elicited much concern because of the lack of available toxicity data. Exposure to ultrafine particles may be a risk for the development of vascular diseases due to dysfunction of the vascular endothelium. Increased endothelial adhesiveness is a critical first step in the development of vascular diseases, such as atherosclerosis. The hypothesis that alumina nanoparticles increase inflammatory markers of the endothelium, measured by the induction of adhesion molecules as well as the adhesion of monocytes to the endothelial monolayer, was tested. Following characterization of alumina nanoparticles by transmission electron microscopy (TEM), electron diffraction, and particle size distribution analysis, endothelial cells were exposed to alumina at various concentrations and times. Both porcine pulmonary artery endothelial cells and human umbilical vein endothelial cells showed increased mRNA and protein expression of VCAM-1, ICAM-1, and ELAM-1. Furthermore, human endothelial cells treated with alumina particles showed increased adhesion of activated monocytes. The alumina particles tended to agglomerate at physiological pH in serum-containing media, which led to a range of particle sizes from nano to micron size during treatment conditions. These data show that alumina nanoparticles can elicit a proinflammatory response and thus present a cardiovascular disease risk.
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Affiliation(s)
- Elizabeth Oesterling
- Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA
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Vrieling EG, Sun Q, Tian M, Kooyman PJ, Gieskes WWC, van Santen RA, Sommerdijk NAJM. Salinity-dependent diatom biosilicification implies an important role of external ionic strength. Proc Natl Acad Sci U S A 2007; 104:10441-6. [PMID: 17563373 PMCID: PMC1965532 DOI: 10.1073/pnas.0608980104] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Indexed: 11/18/2022] Open
Abstract
The role of external ionic strength in diatom biosilica formation was assessed by monitoring the nanostructural changes in the biosilica of the two marine diatom species Thalassiosira punctigera and Thalassiosira weissflogii that was obtained from cultures grown at two distinct salinities. Using physicochemical methods, we found that at lower salinity the specific surface area, the fractal dimensions, and the size of mesopores present in the biosilica decreased. Diatom biosilica appears to be denser at the lower salinity that was applied. This phenomenon can be explained by assuming aggregation of smaller coalescing silica particles inside the silica deposition vesicle, which would be in line with principles in silica chemistry. Apparently, external ionic strength has an important effect on diatom biosilica formation, making it tempting to propose that uptake of silicic acid and other external ions may take place simultaneously. Uptake and transport of reactants in the proximity of the expanding silica deposition vesicle, by (macro)pinocytosis, are more likely than intracellular stabilization and transport of silica precursors at the high concentrations that are necessary for the formation of the siliceous frustule components.
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Affiliation(s)
- Engel G Vrieling
- Groningen Biomolecular Sciences and Biotechnology Institute, Center for Ecological and Evolutionary Studies, University of Groningen, NL-9750 AA Haren, The Netherlands.
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Liu L, Li J, Liu J, Yuan Z, Pierre SV, Qu W, Zhao X, Xie Z. Involvement of Na+/K+-ATPase in hydrogen peroxide-induced hypertrophy in cardiac myocytes. Free Radic Biol Med 2006; 41:1548-56. [PMID: 17045923 DOI: 10.1016/j.freeradbiomed.2006.08.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Revised: 08/08/2006] [Accepted: 08/21/2006] [Indexed: 10/24/2022]
Abstract
We have shown that increased production of reactive oxygen species (ROS) was required for ouabain-induced hypertrophy in cultured cardiac myocytes. In the present study we assessed whether long-term exposure of myocytes to nontoxic ROS stress alone is sufficient to induce hypertrophy. A moderate amount of H2O2 was continuously generated in culture media by glucose oxidase. This resulted in a steady increase in intracellular ROS in cultured cardiac myocytes for at least 12 h. Such sustained, but not transient, increase in intracellular ROS at a level comparable to that induced by ouabain was sufficient to stimulate protein synthesis, increase cell size, and change the expression of several hypertrophic marker genes. Like ouabain, glucose oxidase increased intracellular Ca2+ and activated extracellular signal-regulated kinases 1 and 2 (ERK1/2). These effects of glucose oxidase were additive to ouabain-induced cellular changes. Furthermore, glucose oxidase stimulated endocytosis of the plasma membrane Na+/K+-ATPase, resulting in significant inhibition of sodium pump activity. While inhibition of ERK1/2 abolished glucose oxidase-induced increases in protein synthesis, chelating intracellular Ca2+ by BAPTA-AM showed no effect. These results, taken together with our prior observations, suggest that ROS may cross talk with Na+/K+-ATPase, leading to the activation of hypertrophic pathways in cardiac myocytes.
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Affiliation(s)
- Lijun Liu
- Department of Physiology, Pharmacology, Metabolism and Cardiovascular Sciences, Medical University of Ohio, Toledo, OH 43614, USA
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Hughes S, El Haj AJ, Dobson J. Magnetic micro- and nanoparticle mediated activation of mechanosensitive ion channels. Med Eng Phys 2005; 27:754-62. [PMID: 15985383 DOI: 10.1016/j.medengphy.2005.04.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2005] [Accepted: 04/11/2005] [Indexed: 10/25/2022]
Abstract
Most cells are known to respond to mechanical cues, which initiate biochemical signalling pathways and play a role in cell membrane electrodynamics. These cues can be transduced either via direct activation of mechanosensitive (MS) ion channels or through deformation of the cell membrane and cytoskeleton. Investigation of the function and role of these ion channels is a fertile area of research and studies aimed at characterizing and understanding the mechanoactive regions of these channels and how they interact with the cytoskeleton are fundamental to discovering the specific role that mechanical cues play in cells. In this review, we will focus on novel techniques, which use magnetic micro- and nanoparticles coupled to external applied magnetic fields for activating and investigating MS ion channels and cytoskeletal mechanics.
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Affiliation(s)
- Steven Hughes
- Institute of Science and Technology in Medicine, Keele University, Thornburrow Drive, Hartshill, Stoke-on-Trent, ST4 7QB, UK
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