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Tomé D, Dias MS, Correia J, Almeida RD. Fibroblast growth factor signaling in axons: from development to disease. Cell Commun Signal 2023; 21:290. [PMID: 37845690 PMCID: PMC10577959 DOI: 10.1186/s12964-023-01284-0] [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: 06/07/2023] [Accepted: 08/18/2023] [Indexed: 10/18/2023] Open
Abstract
The fibroblast growth factor (FGF) family regulates various and important aspects of nervous system development, ranging from the well-established roles in neuronal patterning to more recent and exciting functions in axonal growth and synaptogenesis. In addition, FGFs play a critical role in axonal regeneration, particularly after spinal cord injury, confirming their versatile nature in the nervous system. Due to their widespread involvement in neural development, the FGF system also underlies several human neurological disorders. While particular attention has been given to FGFs in a whole-cell context, their effects at the axonal level are in most cases undervalued. Here we discuss the endeavor of the FGF system in axons, we delve into this neuronal subcompartment to provide an original view of this multipurpose family of growth factors in nervous system (dys)function. Video Abstract.
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Affiliation(s)
- Diogo Tomé
- Institute of Biomedicine, Department of Medical Sciences - iBiMED, University of Aveiro, Aveiro, Portugal
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Marta S Dias
- Institute of Biomedicine, Department of Medical Sciences - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Joana Correia
- Institute of Biomedicine, Department of Medical Sciences - iBiMED, University of Aveiro, Aveiro, Portugal
| | - Ramiro D Almeida
- Institute of Biomedicine, Department of Medical Sciences - iBiMED, University of Aveiro, Aveiro, Portugal.
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
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Lu R, Chen J, Wang F, Wang L, Liu J, Lin Y. Lysosome Inhibition Reduces Basal and Nutrient-Induced Fat Accumulation in Caenorhabditis elegans. Mol Cells 2022; 45:649-659. [PMID: 36058890 PMCID: PMC9448645 DOI: 10.14348/molcells.2022.0073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 04/28/2022] [Accepted: 05/02/2022] [Indexed: 11/29/2022] Open
Abstract
A long-term energy nutritional imbalance fundamentally causes the development of obesity and associated fat accumulation. Lysosomes, as nutrient-sensing and lipophagy centers, critically control cellular lipid catabolism in response to nutrient deprivation. However, whether lysosome activity is directly involved in nutrient-induced fat accumulation remains unclear. In this study, worm fat accumulation was induced by 1 mM glucose or 0.02 mM palmitic acid supplementation. Along with the elevation of fat accumulation, lysosomal number and acidification were also increased, suggesting that lysosome activity might be correlated with nutrient-induced fat deposition in Caenorhabditis elegans. Furthermore, treatments with the lysosomal inhibitors chloroquine and leupeptin significantly reduced basal and nutrient-induced fat accumulation in C. elegans. The knockdown of hlh-30, which is a critical gene in lysosomal biogenesis, also resulted in worm fat loss. Finally, the mutation of aak-2, daf-15, and rsks-1 showed that mTORC1 (mechanistic target of rapamycin complex-1) signaling mediated the effects of lysosomes on basal and nutrient-induced fat accumulation in C. elegans. Overall, this study reveals the previously undescribed role of lysosomes in overnutrition sensing, suggesting a new strategy for controlling body fat accumulation.
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Affiliation(s)
- Rui Lu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Juan Chen
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Fangbin Wang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Lu Wang
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
| | - Jian Liu
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
- Engineering Research Center of Bioprocess, Ministry of Education, Hefei University of Technology, Hefei 230009, China
| | - Yan Lin
- School of Food and Biological Engineering, Hefei University of Technology, Hefei 230009, China
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Klimaschewski L, Claus P. Fibroblast Growth Factor Signalling in the Diseased Nervous System. Mol Neurobiol 2021; 58:3884-3902. [PMID: 33860438 PMCID: PMC8280051 DOI: 10.1007/s12035-021-02367-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/19/2021] [Indexed: 12/12/2022]
Abstract
Fibroblast growth factors (FGFs) act as key signalling molecules in brain development, maintenance, and repair. They influence the intricate relationship between myelinating cells and axons as well as the association of astrocytic and microglial processes with neuronal perikarya and synapses. Advances in molecular genetics and imaging techniques have allowed novel insights into FGF signalling in recent years. Conditional mouse mutants have revealed the functional significance of neuronal and glial FGF receptors, not only in tissue protection, axon regeneration, and glial proliferation but also in instant behavioural changes. This review provides a summary of recent findings regarding the role of FGFs and their receptors in the nervous system and in the pathogenesis of major neurological and psychiatric disorders.
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Affiliation(s)
- Lars Klimaschewski
- Department of Anatomy, Histology and Embryology, Institute of Neuroanatomy, Medical University of Innsbruck, Innsbruck, Austria.
| | - Peter Claus
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany
- Center for Systems Neuroscience, Hannover, Germany
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Abstract
Sensitization of the transient receptor potential ion channel vanilloid 1 (TRPV1) is critically involved in inflammatory pain. To date, manifold signaling cascades have been shown to converge onto TRPV1 and enhance its sensitization. However, many of them also play a role for nociceptive pain, which limits their utility as targets for therapeutic intervention. Here, we show that the vesicle transport through interaction with t-SNAREs homolog 1B (Vti1b) protein promotes TRPV1 sensitization upon inflammation in cell culture but leaves normal functioning of TRPV1 intact. Importantly, the effect of Vti1b can be recapitulated in vivo: Virus-mediated knockdown of Vti1b in sensory neurons attenuated thermal hypersensitivity during inflammatory pain without affecting mechanical hypersensitivity or capsaicin-induced nociceptive pain. Interestingly, TRPV1 and Vti1b are localized in close vicinity as indicated by proximity ligation assays and are likely to bind to each other, either directly or indirectly, as suggested by coimmunoprecipitations. Moreover, using a mass spectrometry-based quantitative interactomics approach, we show that Vti1b is less abundant in TRPV1 protein complexes during inflammatory conditions compared with controls. Alongside, we identify numerous novel and pain state-dependent binding partners of native TRPV1 in dorsal root ganglia. These data represent a unique resource on the dynamics of the TRPV1 interactome and facilitate mechanistic insights into TRPV1 regulation. We propose that inflammation-related differences in the TRPV1 interactome identified here could be exploited to specifically target inflammatory pain in the future.
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A Christianson syndrome-linked deletion mutation (Δ287ES288) in SLC9A6 impairs hippocampal neuronal plasticity. Neurobiol Dis 2019; 130:104490. [PMID: 31175985 DOI: 10.1016/j.nbd.2019.104490] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 04/25/2019] [Accepted: 06/04/2019] [Indexed: 02/07/2023] Open
Abstract
Christianson Syndrome is a rare but increasingly diagnosed X-linked intellectual disability disorder that arises from mutations in SLC9A6/NHE6, a pH-regulating transporter that localizes to early and recycling endosomes. We have recently reported that one of the originally identified disease-causing mutations in NHE6 (p.E287-S288del, or ΔES) resulted in a loss of its pH regulatory function. However, the impact of this mutation upon neuronal synapse formation and plasticity is unknown. Here, we investigate the consequences of the ΔES mutant upon mouse hippocampal pyramidal neurons by expressing a fluorescently-labeled ΔES NHE6 construct into primary hippocampal neurons. Neurons expressing the ΔES mutant showed significant reductions in mature dendritic spine density with a concurrent increase in immature filopodia. Furthermore, compared to wild-type (WT), ΔES-containing endosomes are redirected away from early and recycling endosomes toward lysosomes. In parallel, the ΔES mutant reduced the trafficking of glutamatergic AMPA receptors to excitatory synapses and increased their accumulation within lysosomes for potential degradation. Upon long-term potentiation (LTP), neurons expressing ΔES failed to undergo significant structural and functional changes as observed in controls and WT transfectants. Interestingly, synapse density and LTP-induced synaptic remodeling in ΔES-expressing neurons were partially restored by bafilomycin, a vesicular alkalinisation agent, or by leupeptin, an inhibitor of lysosomal proteolytic degradation. Overall, our results demonstrate that the ∆ES mutation attenuates synapse density and structural and functional plasticity in hippocampal neurons. These deficits may be partially due to the mistargeting of AMPA receptors and other cargos to lysosomes, thereby preventing their trafficking during synaptic remodeling. This mechanism may contribute to the cognitive learning deficits observed in patients with Christianson Syndrome and suggests a potential therapeutic strategy for treatment.
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Hausott B, Förste A, Zach F, Mangger S, Haugsten EM, Klimaschewski L. Endocytosis and Transport of Growth Factor Receptors in Peripheral Axon Regeneration: Novel Lessons from Neurons Expressing Lysine-Deficient FGF Receptor Type 1 in vitro. Anat Rec (Hoboken) 2019; 302:1268-1275. [PMID: 30950230 PMCID: PMC6767123 DOI: 10.1002/ar.24120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 12/06/2018] [Accepted: 01/18/2019] [Indexed: 11/13/2022]
Abstract
In the course of peripheral nerve regeneration, axons encounter different extracellular growth factors secreted by non‐neuronal cells at the injury site and retrogradely transported after binding to neuronal membrane receptor tyrosine kinases. The present study reviews the role of receptor transport in peripheral axon outgrowth and provides novel data on trafficking of fibroblast growth factor receptor type 1 (FGFR1). Differences in receptor transport are determined by different numbers of lysine residues acting as ubiquitination sites in the intracellular receptor domain. We previously demonstrated that overexpression of mutant FGFR1‐25R (25 out of 29 intracellular lysines replaced with arginine) results in enhanced receptor recycling as compared to wild‐type FGFR1 followed by strong stimulation of elongative axon growth in vitro. Here, the effects of lysine‐deficient FGFR1 (FGFR1‐29R lacking all 29 cytoplasmic lysine residues) or of only 15 lysine mutations (FGFR1‐15R) on axon outgrowth and concomitant changes in signal pathway activation were investigated by immunocytochemistry and morphometry of cultured primary neurons. Overexpression of FGFR1‐15R in adult sensory neurons resulted in enhanced receptor recycling, which was accompanied by increased axon elongation without stimulating axon branching. By contrast, FGFR1‐29R was neither endocytosed nor axon outgrowth affected. Although overexpression of FGFR1‐15R or FGFR1‐25Ra strongly promoted elongation, we did not detect increased signal pathway activation (ERK, AKT, PLC, or STAT3) in neurons expressing mutant FGFR1 as compared with wild‐type neurons raising the possibility that other signaling pathways or signaling independent mechanisms may be involved in the axon outgrowth effects of recycled FGF receptors. Anat Rec, 302:1268–1275, 2019. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Barbara Hausott
- Department of Anatomy, Histology and Embryology, Division of Neuroanatomy, Medical University Innsbruck, Innsbruck, Austria
| | - Alexandra Förste
- Department of Anatomy, Histology and Embryology, Division of Neuroanatomy, Medical University Innsbruck, Innsbruck, Austria
| | - Fabian Zach
- Department of Anatomy, Histology and Embryology, Division of Neuroanatomy, Medical University Innsbruck, Innsbruck, Austria
| | - Stefan Mangger
- Department of Anatomy, Histology and Embryology, Division of Neuroanatomy, Medical University Innsbruck, Innsbruck, Austria
| | - Ellen Margrethe Haugsten
- Department of Tumor Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo, Norway.,Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Lars Klimaschewski
- Department of Anatomy, Histology and Embryology, Division of Neuroanatomy, Medical University Innsbruck, Innsbruck, Austria
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Membrane-Associated, Not Cytoplasmic or Nuclear, FGFR1 Induces Neuronal Differentiation. Cells 2019; 8:cells8030243. [PMID: 30875802 PMCID: PMC6468866 DOI: 10.3390/cells8030243] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/04/2019] [Accepted: 03/08/2019] [Indexed: 01/22/2023] Open
Abstract
The intracellular transport of receptor tyrosine kinases results in the differential activation of various signaling pathways. In this study, optogenetic stimulation of fibroblast growth factor receptor type 1 (FGFR1) was performed to study the effects of subcellular targeting of receptor kinases on signaling and neurite outgrowth. The catalytic domain of FGFR1 fused to the algal light-oxygen-voltage-sensing (LOV) domain was directed to different cellular compartments (plasma membrane, cytoplasm and nucleus) in human embryonic kidney (HEK293) and pheochromocytoma (PC12) cells. Blue light stimulation elevated the pERK and pPLCγ1 levels in membrane-opto-FGFR1-transfected cells similarly to ligand-induced receptor activation; however, no changes in pAKT levels were observed. PC12 cells transfected with membrane-opto-FGFR1 exhibited significantly longer neurites after light stimulation than after growth factor treatment, and significantly more neurites extended from their cell bodies. The activation of cytoplasmic FGFR1 kinase enhanced ERK signaling in HEK293 cells but not in PC12 cells and did not induce neuronal differentiation. The stimulation of FGFR1 kinase in the nucleus also did not result in signaling changes or neurite outgrowth. We conclude that FGFR1 kinase needs to be associated with membranes to induce the differentiation of PC12 cells mainly via ERK activation.
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Si W, Zhang Y, Chen K, Hu D, Qian Z, Gong S, Li H, Hao Y, Tao J. Fibroblast growth factor type 1 receptor stimulation of T-type Ca2+ channels in sensory neurons requires the phosphatidylinositol 3-kinase and protein kinase A pathways, independently of Akt. Cell Signal 2018; 45:93-101. [DOI: 10.1016/j.cellsig.2018.01.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/25/2018] [Accepted: 01/25/2018] [Indexed: 02/08/2023]
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Smith GA, Fearnley GW, Abdul-Zani I, Wheatcroft SB, Tomlinson DC, Harrison MA, Ponnambalam S. Ubiquitination of basal VEGFR2 regulates signal transduction and endothelial function. Biol Open 2017; 6:1404-1415. [PMID: 28798148 PMCID: PMC5665470 DOI: 10.1242/bio.027896] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/04/2017] [Indexed: 01/19/2023] Open
Abstract
Cell surface receptors can undergo recycling or proteolysis but the cellular decision-making events that sort between these pathways remain poorly defined. Vascular endothelial growth factor A (VEGF-A) and vascular endothelial growth factor receptor 2 (VEGFR2) regulate signal transduction and angiogenesis, but how signaling and proteolysis is regulated is not well understood. Here, we provide evidence that a pathway requiring the E1 ubiquitin-activating enzyme UBA1 controls basal VEGFR2 levels, hence metering plasma membrane receptor availability for the VEGF-A-regulated endothelial cell response. VEGFR2 undergoes VEGF-A-independent constitutive degradation via a UBA1-dependent ubiquitin-linked pathway. Depletion of UBA1 increased VEGFR2 recycling from endosome-to-plasma membrane and decreased proteolysis. Increased membrane receptor availability after UBA1 depletion elevated VEGF-A-stimulated activation of key signaling enzymes such as PLCγ1 and ERK1/2. Although UBA1 depletion caused an overall decrease in endothelial cell proliferation, surviving cells showed greater VEGF-A-stimulated responses such as cell migration and tubulogenesis. Our study now suggests that a ubiquitin-linked pathway regulates the balance between receptor recycling and degradation which in turn impacts on the intensity and duration of VEGF-A-stimulated signal transduction and the endothelial response.
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Affiliation(s)
- Gina A Smith
- Endothelial Cell Biology Unit, School of Molecular & Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Gareth W Fearnley
- Endothelial Cell Biology Unit, School of Molecular & Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Izma Abdul-Zani
- Endothelial Cell Biology Unit, School of Molecular & Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Stephen B Wheatcroft
- Leeds Institute of Cardiovascular & Metabolic Medicine, Faculty of Medicine & Health, University of Leeds, Leeds LS2 9JT, UK
| | - Darren C Tomlinson
- Endothelial Cell Biology Unit, School of Molecular & Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | | | - Sreenivasan Ponnambalam
- Endothelial Cell Biology Unit, School of Molecular & Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
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Weerasinghe SVW, Park MJ, Portney DA, Omary MB. Mouse genetic background contributes to hepatocyte susceptibility to Fas-mediated apoptosis. Mol Biol Cell 2016; 27:3005-3012. [PMID: 27535425 PMCID: PMC5063609 DOI: 10.1091/mbc.e15-06-0423] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 07/15/2016] [Accepted: 08/11/2016] [Indexed: 12/11/2022] Open
Abstract
Liver disease progression is modulated by genetic modifiers in mouse strains and across human races and ethnicities. We hypothesized that hepatocyte culture duration and genetic background regulate hepatocyte susceptibility to apoptosis. Hepatocytes were isolated from FVB/N, C57BL/6, and C3H/He mice and cultured or treated with Fas ligand or acetaminophen after different culture times. Protein and mRNA expressions of Fas receptor, caspases-3/7/8, and Bak/Bax/Bid proteins were determined. FVB/N hepatocytes manifested rapid decreases of caspases-3/7 but not caspase-8 as culture time increased, which paralleled decreased susceptibility to apoptosis. Some changes were also found in Fas-receptor and Bak, Bax, and Bid proteins; caspase mRNA decreases were also noted. Caspase protein degradation was partially reversed by lysosomal protease but not proteasome or autophagy inhibitors. C57BL/6 and FVB/N hepatocytes behaved similarly in their limited susceptibility to apoptosis, whereas C3H/He hepatocytes show limited alterations in caspases, with consequent increased susceptibility to apoptosis. Similarly, C3H/He mice were more susceptible than C57BL/6 and FVB/N mice to Fas-mediated liver injury. Therefore there are significant mouse strain-dependent differences in susceptibility to apoptosis and selective loss of caspases upon short-term hepatocyte culture, with consequent decrease in susceptibility to apoptosis. These differences likely reflect genetic modifiers that provide resistance or predisposition to hepatocyte death.
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Affiliation(s)
- Sujith V W Weerasinghe
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Min-Jung Park
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Daniel A Portney
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - M Bishr Omary
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109 Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109
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Das S, Singh G, Majid M, Sherman MB, Mukhopadhyay S, Wright CS, Martin PE, Dunn AK, Baker AB. Syndesome Therapeutics for Enhancing Diabetic Wound Healing. Adv Healthc Mater 2016; 5:2248-60. [PMID: 27385307 PMCID: PMC5228475 DOI: 10.1002/adhm.201600285] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/24/2016] [Indexed: 12/19/2022]
Abstract
Chronic wounds represent a major healthcare and economic problem worldwide. Advanced wound dressings that incorporate bioactive compounds have great potential for improving outcomes in patients with chronic wounds but significant challenges in designing treatments that are effective in long-standing, nonhealing wounds. Here, an optimized wound healing gel was developed that delivers syndecan-4 proteoliposomes ("syndesomes") with fibroblast growth factor-2 (FGF-2) to enhance diabetic wound healing. In vitro studies demonstrate that syndesomes markedly increase migration of keratinocytes and fibroblasts isolated from both nondiabetic and diabetic donors. In addition, syndesome treatment leads to increased endocytic processing of FGF-2 that includes enhanced recycling of FGF-2 to the cell surface after uptake. The optimized syndesome formulation was incorporated into an alginate wound dressing and tested in a splinted wound model in diabetic, ob/ob mice. It was found that wounds treated with syndesomes and FGF-2 have markedly enhanced wound closure in comparison to wounds treated with only FGF-2. Moreover, syndesomes have an immunomodulatory effect on wound macrophages, leading to a shift toward the M2 macrophage phenotype and alterations in the wound cytokine profile. Together, these studies show that delivery of exogenous syndecan-4 is an effective method for enhancing wound healing in the long-term diabetic diseased state.
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Affiliation(s)
- Subhamoy Das
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78731, USA
| | - Gunjan Singh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78731, USA
| | - Marjan Majid
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78731, USA
| | - Michael B Sherman
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, 77555, USA
| | - Somshuvra Mukhopadhyay
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, TX, 78731, USA
- Institute for Neuroscience, University of Texas at Austin, Austin, TX, 78731, USA
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, 78731, USA
| | - Catherine S Wright
- Diabetes Research Group, Department of Life Sciences and Institute for Applied Health Research, Glasgow Caledonian University, Glasgow, G4 0BA, UK
| | - Patricia E Martin
- Diabetes Research Group, Department of Life Sciences and Institute for Applied Health Research, Glasgow Caledonian University, Glasgow, G4 0BA, UK
| | - Andrew K Dunn
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78731, USA
| | - Aaron B Baker
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX, 78731, USA.
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, 78731, USA.
- The Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, TX, 78731, USA.
- Institute for Biomaterials, Drug Delivery and Regenerative Medicine, University of Texas at Austin, Austin, 78731, USA.
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Abstract
Peripheral axonal regeneration requires surface-expanding membrane addition. The continuous incorporation of new membranes into the axolemma allows the pushing force of elongating microtubules to drive axonal growth cones forwards. Hence, a constant supply of membranes and cytoskeletal building blocks is required, often for many weeks. In human peripheral nerves, axonal tips may be more than 1 m away from the neuronal cell body. Therefore, in the initial phase of regeneration, membranes are derived from pre-existing vesicles or synthesised locally. Only later stages of axonal regeneration are supported by membranes and proteins synthesised in neuronal cell bodies, considering that the fastest anterograde transport mechanisms deliver cargo at 20 cm/day. Whereas endocytosis and exocytosis of membrane vesicles are balanced in intact axons, membrane incorporation exceeds membrane retrieval during regeneration to compensate for the loss of membranes distal to the lesion site. Physiological membrane turnover rates will not be established before the completion of target reinnervation. In this review, the current knowledge on membrane traffic in axonal outgrowth is summarised, with a focus on endosomal vesicles as the providers of membranes and carriers of growth factor receptors required for initiating signalling pathways to promote the elongation and branching of regenerating axons in lesioned peripheral nerves.
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Affiliation(s)
- Barbara Hausott
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Medical University Innsbruck, 6020, Innsbruck, Austria
| | - Lars Klimaschewski
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Medical University Innsbruck, 6020, Innsbruck, Austria
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Hausner T, Marvaldi L, Márton G, Pajer K, Hopf R, Schmidhammer R, Hausott B, Redl H, Nógrádi A, Klimaschewski L. Inhibition of calpains fails to improve regeneration through a peripheral nerve conduit. Neurosci Lett 2014; 566:280-5. [PMID: 24631569 PMCID: PMC4000267 DOI: 10.1016/j.neulet.2014.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 02/18/2014] [Accepted: 03/05/2014] [Indexed: 12/17/2022]
Abstract
Calpain inhibitor leupeptin locally applied to transected sciatic nerve of rats. Axon number and myelination not significantly increased 3 months after lesion. No difference in behavioral tests after nerve regeneration.
Intramuscular injection of the calpain inhibitor leupeptin promotes peripheral nerve regeneration in primates (Badalamente et al., 1989 [13]), and direct positive effects of leupeptin on axon outgrowth were observed in vitro (Hausott et al., 2012 [12]). In this study, we applied leupeptin (2 mg/ml) directly to collagen-filled nerve conduits in the rat sciatic nerve transection model. Analysis of myelinated axons and retrogradely labeled motoneurons as well as functional ‘CatWalk’ video analysis did not reveal significant differences between vehicle controls and leupeptin treated animals. Therefore, leupeptin does not improve nerve regeneration via protease inhibition in regrowing axons or in surrounding Schwann cells following a single application to a peripheral nerve conduit suggesting indirect effects on motor endplate integrity if applied systemically.
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Affiliation(s)
- Thomas Hausner
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria; Department of Trauma Surgery and Sports Traumatology, Paracelsus Medical University, Müllner Hauptstr. 48-50, 5020 Salzburg, Austria; Department of Surgery, State Hospital Hainburg, Hofmeisterstr. 70, 2410 Hainburg, Austria
| | - Letizia Marvaldi
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Innsbruck Medical University, Muellerstrasse 59, 6020 Innsbruck, Austria
| | - Gábor Márton
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Hungary
| | - Krisztián Pajer
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Hungary
| | - Rudolf Hopf
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria
| | - Robert Schmidhammer
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria; Vienna Private Clinic, Pelikangasse 15, 1090 Vienna, Austria
| | - Barbara Hausott
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Innsbruck Medical University, Muellerstrasse 59, 6020 Innsbruck, Austria
| | - Heinz Redl
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria
| | - Antal Nógrádi
- Austrian Cluster of Tissue Regeneration and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology at the Research Centre for Traumatology of the Austrian Workers' Compensation Board (AUVA), Donaueschingenstr. 13, 1200 Vienna, Austria; Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Szeged, Hungary.
| | - Lars Klimaschewski
- Division of Neuroanatomy, Department of Anatomy, Histology and Embryology, Innsbruck Medical University, Muellerstrasse 59, 6020 Innsbruck, Austria.
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14
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Zakrzewska M, Haugsten EM, Nadratowska-Wesolowska B, Oppelt A, Hausott B, Jin Y, Otlewski J, Wesche J, Wiedlocha A. ERK-Mediated Phosphorylation of Fibroblast Growth Factor Receptor 1 on Ser777 Inhibits Signaling. Sci Signal 2013; 6:ra11. [DOI: 10.1126/scisignal.2003087] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Irschick R, Trost T, Karp G, Hausott B, Auer M, Claus P, Klimaschewski L. Sorting of the FGF receptor 1 in a human glioma cell line. Histochem Cell Biol 2013; 139:135-48. [PMID: 22903848 DOI: 10.1007/s00418-012-1009-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2012] [Indexed: 12/11/2022]
Abstract
Fibroblast growth factor receptor 1 (FGFR1) is a receptor tyrosine kinase promoting tumor growth in a variety of cancers, including glioblastoma. Binding of FGFs triggers the intracellular Ras/Raf/ERK signaling pathway leading to cell proliferation. Down-regulation of FGFR1 and, consequently, inactivation of its signaling pathways represent novel treatment strategies for glioblastoma. In this study, we investigated the internalization and endocytic trafficking of FGFR1 in the human glioma cell line U373. Stimulation with FGF-2 induced cell rounding accompanied by increased BrdU and pERK labeling. The overexpression of FGFR1 (without FGF treatment) resulted in enhanced phosphorylated FGFR1 suggesting receptor autoactivation. Labeled ligand (FGF-2-Cy5.5) was endocytosed in a clathrin- and caveolin-dependent manner. About 25 % of vesicles carrying fluorescently tagged FGFR1 represented early endosomes, 15 % transferrin-positive recycling endosomes and 40 % Lamp1-positive late endosomal/lysosomal vesicles. Stimulation with FGF-2 increased the colocalization rate in each of these vesicle populations. The treatment with the lysosomal inhibitor leupeptin resulted in FGFR1 accumulation in lysosomes, but did not enhance receptor recycling as observed in neurons. Analysis of vesicle distributions revealed an accumulation of recycling endosomes in the perinuclear region. In conclusion, the shuttling of receptor tyrosine kinases can be directly visualized by overexpression of fluorescently tagged receptors which respond to ligand stimulation and follow the recycling and degradation pathways similarly to their endogenous counterparts.
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Affiliation(s)
- Regina Irschick
- Division of Neuroanatomy, Medical University Innsbruck, Muellerstrasse 59, 6020 Innsbruck, Austria
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Klimaschewski L, Hausott B, Angelov DN. The pros and cons of growth factors and cytokines in peripheral axon regeneration. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2013; 108:137-71. [PMID: 24083434 DOI: 10.1016/b978-0-12-410499-0.00006-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Injury to a peripheral nerve induces a complex cellular and molecular response required for successful axon regeneration. Proliferating Schwann cells organize into chains of cells bridging the lesion site, which is invaded by macrophages. Approximately half of the injured neuron population sends out axons that enter the glial guidance channels in response to secreted neurotrophic factors and neuropoietic cytokines. These lesion-associated polypeptides create an environment that is highly supportive for axon regrowth, particularly after acute injury, and ensure that the vast majority of regenerating axons are directed toward the distal nerve stump. Unfortunately, most neurotrophic factors and neuropoietic cytokines are also strong stimulators of axonal sprouting. Although some of the axonal branches will withdraw at later stages, the sprouting effect contributes to the misdirection of reinnervation that results in the lack of functional recovery observed in many patients with peripheral nerve injuries. Here, we critically review the role of neuronal growth factors and cytokines during axon regeneration in the peripheral nervous system. Their differential effects on axon elongation and sprouting were elucidated in various studies on intraneuronal signaling mechanisms following nerve lesion. The present data define a goal for future therapeutic strategies, namely, to selectively stimulate a Ras/Raf/ERK-mediated axon elongation program over an intrinsic PI3K-dependent axonal sprouting program in lesioned motor and sensory neurons. Instead of modulating growth factor or cytokine levels at the lesion site, targeting specific intraneuronal molecules, such as the negative feedback inhibitors of ERK signaling, has been shown to promote long-distance regeneration while avoiding sprouting of regenerating axons until they have reached their target areas.
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Affiliation(s)
- Lars Klimaschewski
- Division of Neuroanatomy, Department of Anatomy and Histology, Innsbruck Medical University, Innsbruck, Austria
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