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Guo L, Choi S, Bikkannavar P, Cordeiro MF. Microglia: Key Players in Retinal Ageing and Neurodegeneration. Front Cell Neurosci 2022; 16:804782. [PMID: 35370560 PMCID: PMC8968040 DOI: 10.3389/fncel.2022.804782] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 02/11/2022] [Indexed: 12/20/2022] Open
Abstract
Microglia are the resident immune cells of the central nervous system (CNS) and play a key role in maintaining the normal function of the retina and brain. During early development, microglia migrate into the retina, transform into a highly ramified phenotype, and scan their environment constantly. Microglia can be activated by any homeostatic disturbance that may endanger neurons and threaten tissue integrity. Once activated, the young microglia exhibit a high diversity in their phenotypes as well as their functions, which relate to either beneficial or harmful consequences. Microglial activation is associated with the release of cytokines, chemokines, and growth factors that can determine pathological outcomes. As the professional phagocytes in the retina, microglia are responsible for the clearance of pathogens, dead cells, and protein aggregates. However, their phenotypic diversity and phagocytic capacity is compromised with ageing. This may result in the accumulation of protein aggregates and myelin debris leading to retinal neuroinflammation and neurodegeneration. In this review, we describe microglial phenotypes and functions in the context of the young and ageing retina, and the mechanisms underlying changes in ageing. Additionally, we review microglia-mediated retinal neuroinflammation and discuss the mechanisms of microglial involvement in retinal neurodegenerative diseases.
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Affiliation(s)
- Li Guo
- Institute of Ophthalmology, University College London, London, United Kingdom
- *Correspondence: Li Guo,
| | - Soyoung Choi
- Institute of Ophthalmology, University College London, London, United Kingdom
| | | | - M. Francesca Cordeiro
- Institute of Ophthalmology, University College London, London, United Kingdom
- Imperial College Ophthalmology Research Group, Imperial College London, London, United Kingdom
- M. Francesca Cordeiro,
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Dyne E, Cawood M, Suzelis M, Russell R, Kim MH. Ultrastructural analysis of the morphological phenotypes of microglia associated with neuroinflammatory cues. J Comp Neurol 2021; 530:1263-1275. [PMID: 34773250 DOI: 10.1002/cne.25274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 12/15/2022]
Abstract
Microglia are the primary resident immune cells of the central nervous system that are responsible for the maintenance of brain homeostasis. There is a plethora of evidence to suggest that microglia display distinct phenotypes that are associated with the alteration of cell morphology under varying environmental cues. However, it has not been fully explored how the varying states of microglial activation are linked to the alteration of microglia morphology, especially in the microdomain. The objective of this study was to quantitatively characterize the ultrastructural morphology of human microglia under neuroinflammatory cues. To address this, a human cell line of microglia was stimulated by antiinflammatory (IL-4), proinflammatory (TNF-α), and Alzheimer's disease (AD)-associated cues (Aβ, Aβ + TNF-α). The resulting effects on microglia morphology associated with changes in microdomain were analyzed using a high-resolution scanning electron microscopy. Our findings demonstrated that microglial activation under proinflammatory and AD-cues were closely linked to changes not only in cell shape but also in cell surface topography and higher-order branching of processes. Furthermore, our results revealed that microglia under proinflammatory cues exhibited unique morphological features involving cell-to-cell contact and the formation of vesicle-like structures. Our study provides insight into the fine details of microglia morphology associated with varying status of microglial activation.
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Affiliation(s)
- Eric Dyne
- School of Biomedical Sciences, Kent State University, Kent, Ohio, USA
| | - Meghan Cawood
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Matthew Suzelis
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Reagan Russell
- Department of Biological Sciences, Kent State University, Kent, Ohio, USA
| | - Min-Ho Kim
- School of Biomedical Sciences, Kent State University, Kent, Ohio, USA.,Department of Biological Sciences, Kent State University, Kent, Ohio, USA
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3
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Basu M, Chatterjee A, Chakraborty B, Chatterjee E, Ghosh S, Samadder S, Pal DK, Roy A, Chakrabarti J, Ghosh A, Panda CK. High nuclear expression of HIF1α, synergizing with inactivation of LIMD1 and VHL, portray worst prognosis among the bladder cancer patients: association with arsenic prevalence. J Cancer Res Clin Oncol 2021; 147:2309-2322. [PMID: 34080067 DOI: 10.1007/s00432-021-03661-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 05/05/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE Our study was aimed to understand the importance of LIMD1-VHL-HIF1α pathway in development of bladder carcinoma (BlCa) in association with arsenic prevalence. METHODS At first, the mRNA expression pattern of the genes of this pathway (LIMD1, VHL and HIF1α) was checked in GEO datasets and in our samples. Next, genetic and epigenetic profiling of LIMD1 and VHL was done in our sample pool, validated in T24 BlCa cell line. The results were next correlated with various clinico-pathological parameters. RESULTS Differential under-expression of LIMD1 and VHL genes was found in muscle-invasive BlCa (MIBC) in comparison to non-muscle-invasive BlCa (NMIBC). However, HIF1α protein, but mRNA, was found to be overexpressed among the MIBC samples; depicting the probability of HIF1α protein stabilization. Analysis of genetic and epigenetic profiles of LIMD1 and VHL exposed a frequent promoter methylation of LIMD1 gene in MIBC samples. Further, in-depth look into the results unveiled that the high nuclear expression of HIF1α was significantly correlated with genetic alterations of LIMD1, alone or in combination with VHL. Moreover, treating the T24 cells with a de-methylating agent (5-aza-2'-deoxycytidine) re-expressed the methylated LIMD1 and VHL genes, which in turn, reduced the HIF1α protein level significantly. Additionally, patients with high arsenic content (> 112 ng/g, AsH) seemed to have recurrent promoter methylation in LIMD1, as well as co-methylation/alteration of LIMD1 and VHL gene. Lastly, high nuclear expression of HIF1α in association with co-alteration of VHL and LIMD1 showed the worst overall survival (OS) among the patients. CONCLUSION To conclude, MIBC samples portrayed higher alterations in VHL and LIMD1, thereby, stabilizing HIF1α protein and lowering the OS of patients.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Arsenic Poisoning/diagnosis
- Arsenic Poisoning/epidemiology
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Transitional Cell/diagnosis
- Carcinoma, Transitional Cell/epidemiology
- Carcinoma, Transitional Cell/genetics
- Carcinoma, Transitional Cell/pathology
- Cell Line, Tumor
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Cell Nucleus/pathology
- Comorbidity
- DNA Methylation
- Datasets as Topic
- Female
- Gene Expression Regulation, Neoplastic
- Gene Silencing
- Humans
- Hypoxia-Inducible Factor 1, alpha Subunit/genetics
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Intracellular Signaling Peptides and Proteins/genetics
- Intracellular Signaling Peptides and Proteins/metabolism
- LIM Domain Proteins/genetics
- LIM Domain Proteins/metabolism
- Male
- Middle Aged
- Neoplasm Invasiveness
- Prevalence
- Prognosis
- Survival Analysis
- Urinary Bladder Neoplasms/diagnosis
- Urinary Bladder Neoplasms/epidemiology
- Urinary Bladder Neoplasms/genetics
- Urinary Bladder Neoplasms/pathology
- Von Hippel-Lindau Tumor Suppressor Protein/genetics
- Von Hippel-Lindau Tumor Suppressor Protein/metabolism
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Affiliation(s)
- Mukta Basu
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, 37 S. P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Amvrin Chatterjee
- Department of Urology, IPGMER, SSKM, 244 A.J.C. Bose Road, Kolkata, 700020, India
| | - Balarko Chakraborty
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, 37 S. P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Essha Chatterjee
- National Institute of Pharmaceutical Education and Research, Kukatpally Industrial Estate, Balanagar, Hyderabad, Telangana, 500037, India
| | - Sabnam Ghosh
- Department of Life Science, Presidency University, 86/1, College Street, Kolkata, 700073, India
| | - Sudip Samadder
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, 37 S. P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Dilip Kumar Pal
- Department of Urology, IPGMER, SSKM, 244 A.J.C. Bose Road, Kolkata, 700020, India
| | - Anup Roy
- Nil Ratan Sarkar Medical College and Hospital, Kolkata, West Bengal, India
| | - Jayanta Chakrabarti
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, 37 S. P. Mukherjee Road, Kolkata, West Bengal, 700026, India
| | - Amlan Ghosh
- Department of Life Science, Presidency University, 86/1, College Street, Kolkata, 700073, India
| | - Chinmay Kumar Panda
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, 37 S. P. Mukherjee Road, Kolkata, West Bengal, 700026, India.
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Franco-Bocanegra DK, McAuley C, Nicoll JAR, Boche D. Molecular Mechanisms of Microglial Motility: Changes in Ageing and Alzheimer's Disease. Cells 2019; 8:cells8060639. [PMID: 31242692 PMCID: PMC6627151 DOI: 10.3390/cells8060639] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/21/2019] [Accepted: 06/24/2019] [Indexed: 12/25/2022] Open
Abstract
Microglia are the tissue-resident immune cells of the central nervous system, where they constitute the first line of defense against any pathogens or injury. Microglia are highly motile cells and in order to carry out their function, they constantly undergo changes in their morphology to adapt to their environment. The microglial motility and morphological versatility are the result of a complex molecular machinery, mainly composed of mechanisms of organization of the actin cytoskeleton, coupled with a “sensory” system of membrane receptors that allow the cells to perceive changes in their microenvironment and modulate their responses. Evidence points to microglia as accountable for some of the changes observed in the brain during ageing, and microglia have a role in the development of neurodegenerative diseases, such as Alzheimer’s disease. The present review describes in detail the main mechanisms driving microglial motility in physiological conditions, namely, the cytoskeletal actin dynamics, with emphasis in proteins highly expressed in microglia, and the role of chemotactic membrane proteins, such as the fractalkine and purinergic receptors. The review further delves into the changes occurring to the involved proteins and pathways specifically during ageing and in Alzheimer’s disease, analyzing how these changes might participate in the development of this disease.
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Affiliation(s)
- Diana K Franco-Bocanegra
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK.
| | - Ciaran McAuley
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK.
| | - James A R Nicoll
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK.
- Department of Cellular Pathology, University Hospital Southampton NHS Foundation Trust, Southampton SO16 6YD, UK.
| | - Delphine Boche
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK.
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Ravinder R, Goyal N. Cloning, characterization and subcellular localization of Nuclear LIM interactor interacting factor gene from Leishmania donovani. Gene 2017; 611:1-8. [DOI: 10.1016/j.gene.2017.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 02/04/2017] [Accepted: 02/06/2017] [Indexed: 12/30/2022]
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Sukumaran SK, Blau-Wasser R, Rohlfs M, Gallinger C, Schleicher M, Noegel AA. The centrosomal component CEP161 of Dictyostelium discoideum interacts with the Hippo signaling pathway. Cell Cycle 2015; 14:1024-35. [PMID: 25607232 PMCID: PMC4614953 DOI: 10.1080/15384101.2015.1007015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
CEP161 is a novel component of the Dictyostelium discoideum centrosome which was identified as binding partner of the pericentriolar component CP250. Here we show that the amino acids 1-763 of the 1381 amino acids CEP161 are sufficient for CP250 binding, centrosomal targeting and centrosome association. Analysis of AX2 cells over-expressing truncated and full length CEP161 proteins revealed defects in growth and development. By immunoprecipitation experiments we identified the Hippo related kinase SvkA (Hrk-svk) as binding partner for CEP161. Both proteins colocalize at the centrosome. In in vitro kinase assays the N-terminal domain of CEP161 (residues 1-763) inhibited the kinase activity of Hrk-svk. A comparison of D. discoideum Hippo kinase mutants with mutants overexpressing CEP161 polypeptides revealed similar defects. We propose that the centrosomal component CEP161 is a novel player in the Hippo signaling pathway and affects various cellular properties through this interaction.
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Affiliation(s)
- Salil K Sukumaran
- a Institute of Biochemistry I; Medical Faculty University of Cologne ; Köln , Germany
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7
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The Dictyostelium discoideum GPHR ortholog is an endoplasmic reticulum and Golgi protein with roles during development. EUKARYOTIC CELL 2014; 14:41-54. [PMID: 25380752 DOI: 10.1128/ec.00208-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Dictyostelium discoideum GPHR (Golgi pH regulator)/Gpr89 is a developmentally regulated transmembrane protein present on the endoplasmic reticulum (ER) and the Golgi apparatus. Transcript levels are low during growth and vary during development, reaching high levels during the aggregation and late developmental stages. The Arabidopsis ortholog was described as a G protein-coupled receptor (GPCR) for abscisic acid present at the plasma membrane, whereas the mammalian ortholog is a Golgi apparatus-associated anion channel functioning as a Golgi apparatus pH regulator. To probe its role in D. discoideum, we generated a strain lacking GPHR. The mutant had different growth characteristics than the AX2 parent strain, exhibited changes during late development, and formed abnormally shaped small slugs and fruiting bodies. An analysis of development-specific markers revealed that their expression was disturbed. The distributions of the endoplasmic reticulum and the Golgi apparatus were unaltered at the immunofluorescence level. Likewise, their functions did not appear to be impaired, since membrane proteins were properly processed and glycosylated. Also, changes in the external pH were sensed by the ER, as indicated by a pH-sensitive ER probe, as in the wild type.
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8
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Müller R, Herr C, Sukumaran SK, Omosigho NN, Plomann M, Riyahi TY, Stumpf M, Swaminathan K, Tsangarides M, Yiannakou K, Blau-Wasser R, Gallinger C, Schleicher M, Kolanus W, Noegel AA. The cytohesin paralog Sec7 of Dictyostelium discoideum is required for phagocytosis and cell motility. Cell Commun Signal 2013; 11:54. [PMID: 23915312 PMCID: PMC3737031 DOI: 10.1186/1478-811x-11-54] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 07/29/2013] [Indexed: 12/26/2022] Open
Abstract
Background Dictyostelium harbors several paralogous Sec7 genes that encode members of three subfamilies of the Sec7 superfamily of guanine nucleotide exchange factors. One of them is the cytohesin family represented by three members in D. discoideum, SecG, Sec7 and a further protein distinguished by several transmembrane domains. Cytohesins are characterized by a Sec7-PH tandem domain and have roles in cell adhesion and migration. Results We study here Sec7. In vitro its PH domain bound preferentially to phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2), phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3). When following the distribution of GFP-Sec7 in vivo we observed the protein in the cytosol and at the plasma membrane. Strikingly, when cells formed pseudopods, macropinosomes or phagosomes, GFP-Sec7 was conspicuously absent from areas of the plasma membrane which were involved in these processes. Mutant cells lacking Sec7 exhibited an impaired phagocytosis and showed significantly reduced speed and less persistence during migration. Cellular properties associated with mammalian cytohesins like cell-cell and cell-substratum adhesion were not altered. Proteins with roles in membrane trafficking and signal transduction have been identified as putative interaction partners consistent with the data obtained from mutant analysis. Conclusions Sec7 is a cytosolic component and is associated with the plasma membrane in a pattern distinctly different from the accumulation of PI(3,4,5)P3. Mutant analysis reveals that loss of the protein affects cellular processes that involve membrane flow and the actin cytoskeleton.
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Affiliation(s)
- Rolf Müller
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, 50931 Köln, Germany
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9
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Rout AK, Patel S, Somlata, Shukla M, Saraswathi D, Bhattacharya A, Chary KVR. Functional manipulation of a calcium-binding protein from Entamoeba histolytica guided by paramagnetic NMR. J Biol Chem 2013; 288:23473-87. [PMID: 23782698 DOI: 10.1074/jbc.m112.411058] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
EhCaBP1, one of the calcium-binding proteins from Entamoeba histolytica, is a two-domain EF-hand protein. The two domains of EhCaBP1 are structurally and functionally different from each other. However, both domains are required for structural stability and a full range of functional diversity. Analysis of sequence and structure of EhCaBP1 and other CaBPs indicates that the C-terminal domain of EhCaBP1 possesses a unique structure compared with other family members. This had been attributed to the absence of a Phe-Phe interaction between highly conserved Phe residues at the -4 position in EF-hand III (F[-4]; Tyr(81)) and at the 13th position in EF-hand IV (F[+13]; Phe(129)) of the C-terminal domain. Against this backdrop, we mutated the Tyr residue at the -4th position of EF III to the Phe residue (Y81F), to bring in the Phe-Phe interaction and understand the nature of structural and functional changes in the protein by NMR spectroscopy, molecular dynamics (MD) simulation, isothermal titration calorimetry (ITC), and biological assays, such as imaging and actin binding. The Y81F mutation in EhCaBP1 resulted in a more compact structure for the C-terminal domain of the mutant as in the case of calmodulin and troponin C. The compact structure is favored by the presence of a π-π interaction between Phe(81) and Phe(129) along with several hydrophobic interactions of Phe(81), which are not seen in the wild-type protein. Furthermore, the biological assays reveal preferential membrane localization of the mutant, loss of its colocalization with actin in the phagocytic cups, whereas retaining its ability to bind G- and F-actin.
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Affiliation(s)
- Ashok K Rout
- Tata Institute of Fundamental Research, Mumbai, India
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Clark KA, Kadrmas JL. Drosophila melanogaster muscle LIM protein and alpha-actinin function together to stabilize muscle cytoarchitecture: a potential role for Mlp84B in actin-crosslinking. Cytoskeleton (Hoboken) 2013; 70:304-16. [PMID: 23606669 PMCID: PMC3716849 DOI: 10.1002/cm.21106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 02/06/2023]
Abstract
Stabilization of tissue architecture during development and growth is essential to maintain structural integrity. Because of its contractile nature, muscle is especially susceptible to physiological stresses, and has multiple mechanisms to maintain structural integrity. The Drosophila melanogaster Muscle LIM Protein (MLP), Mlp84B, participates in muscle maintenance, yet its precise mechanism of action is still controversial. Through a candidate approach, we identified α-actinin as a protein that functions with Mlp84B to ensure muscle integrity. α-actinin RNAi animals die primarily as pupae, and Mlp84B RNAi animals are adult viable. RNAi knockdown of Mlp84B and α-actinin together produces synergistic early larval lethality and destabilization of Z-line structures. We recapitulated these phenotypes using combinations of traditional loss-of-function alleles and single-gene RNAi. We observe that Mlp84B induces the formation of actin loops in muscle cell nuclei in the absence of nuclear α-actinin, suggesting Mlp84B has intrinsic actin cross-linking activity, which may complement α-actinin cross-linking activity at sites of actin filament anchorage. These results reveal a molecular mechanism for MLP stabilization of muscle and implicate reduced actin crosslinking as the primary destabilizing defect in MLP-associated cardiomyopathies. Our data support a model in which α-actinin and Mlp84B have important and overlapping functions at sites of actin filament anchorage to preserve muscle structure and function.
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Affiliation(s)
- Kathleen A. Clark
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
- Department of Biology, University of Utah, Salt Lake City, UT 84112
- Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Julie L. Kadrmas
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
- Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
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Miller PW, Clarke DN, Weis WI, Lowe CJ, Nelson WJ. The evolutionary origin of epithelial cell-cell adhesion mechanisms. CURRENT TOPICS IN MEMBRANES 2013; 72:267-311. [PMID: 24210433 PMCID: PMC4118598 DOI: 10.1016/b978-0-12-417027-8.00008-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A simple epithelium forms a barrier between the outside and the inside of an organism, and is the first organized multicellular tissue found in evolution. We examine the relationship between the evolution of epithelia and specialized cell-cell adhesion proteins comprising the classical cadherin/β-catenin/α-catenin complex (CCC). A review of the divergent functional properties of the CCC in metazoans and non-metazoans, and an updated phylogenetic coverage of the CCC using recent genomic data reveal: (1) The core CCC likely originated before the last common ancestor of unikonts and their closest bikont sister taxa. (2) Formation of the CCC may have constrained sequence evolution of the classical cadherin cytoplasmic domain and β-catenin in metazoa. (3) The α-catenin-binding domain in β-catenin appears to be the favored mutation site for disrupting β-catenin function in the CCC. (4) The ancestral function of the α/β-catenin heterodimer appears to be an actin-binding module. In some metazoan groups, more complex functions of α-catenin were gained by sequence divergence in the non-actin-binding (N-, M-) domains. (5) Allosteric regulation of α-catenin may have evolved for more complex regulation of the actin cytoskeleton.
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Affiliation(s)
- Phillip W. Miller
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
| | | | - William I. Weis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
| | | | - W. James Nelson
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biology, Stanford University, Stanford, CA 94305
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Ye J, Xu M. Actin bundler PLIM2s are involved in the regulation of pollen development and tube growth in Arabidopsis. JOURNAL OF PLANT PHYSIOLOGY 2012; 169:516-22. [PMID: 22209219 DOI: 10.1016/j.jplph.2011.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 11/23/2011] [Accepted: 11/23/2011] [Indexed: 05/21/2023]
Abstract
Microspores develop inside the anther, where they are surrounded by nourishing tapetal cells. However, many cellular processes occurring during microspore development in the locule are poorly characterized. The actin cytoskeleton is known to play a crucial role in various aspects of the plant developmental process. During pollen tube tip growth, actin cytoskeleton serves as an efficient molecular transportation track, although how it functions in pollen development is unknown. The plant actin bundler PLIM2s have been shown to regulate actin bundling in different cells. Here, we investigate the biological function of three Arabidopsis pollen-specific LIM proteins, PLIM2a, PLIM2b, and PLIM2c (collectively, PLIM2s), in pollen development and tube growth. Variable degrees of suppressed expression of the PLIM2s by RNA interference resulted in aberrant phenotypes. Complete suppression of the PLIM2s totally disrupted pollen development, producing abortive pollen grains and rendering the transgenic plants sterile. Partial suppression of the PLIM2s arrested pollen tube growth to a lesser extent, resulting in short and swollen pollen tubes. Finally, the PLIM2c promoter initiated expression in pollen during stamen filament elongation, and the PLIM2c protein was located on particle structures in the developing pollen grains in Arabidopsis. These suggest that the actin bundler, PLIM2s, are an important factor for Arabidopsis pollen development and tube growth.
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Affiliation(s)
- Jianrong Ye
- National Maize Improvement Center of China, China Agricultural University, 2 West Yuanmingyuan Road, Beijing 100193, PR China.
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Amann K, Ridinger H, Rutenberg C, Ritz E, Mall G, Maercker C. Gene expression profiling on global cDNA arrays gives hints concerning potential signal transduction pathways involved in cardiac fibrosis of renal failure. Comp Funct Genomics 2010; 4:571-83. [PMID: 18629021 PMCID: PMC2447303 DOI: 10.1002/cfg.347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2003] [Revised: 09/03/2003] [Accepted: 10/10/2003] [Indexed: 01/07/2023] Open
Abstract
Cardiac remodelling with interstitial fibrosis in renal failure, which so far is only poorly understood on the molecular level, was investigated in the rat model by a global
gene expression profiling analysis. Sprague–Dawley rats were subjected to subtotal
nephrectomy (SNX) or sham operation (sham) and followed for 2 and 12 weeks,
respectively. Heart-specific gene expression profiling, with RZPD Rat Unigene-1
cDNA arrays containing about 27 000 gene and EST sequences revealed substantial
changes in gene expression in SNX compared to sham animals. Motor protein genes,
growth and differentiation markers, and extracellular matrix genes were upregulated
in SNX rats. Obviously, not only genes involved in cardiomyocyte hypertrophy, but
also genes involved in the expansion of non-vascular interstitial tissue are activated
very early in animals with renal failure. Together with earlier findings in the SNX
model, the present data suggest the hypothesis that the local renin–angiotensin system
(RAS) may be activated by at least two pathways: (a) via second messengers and Gproteins
(short-term signalling); and (b) via motor proteins, actins and integrins (longterm
signalling). The study documents that complex hybridization analysis yields
reproducible and promising results of patterns of gene activation pointing to signalling
pathways involved in cardiac remodelling in renal failure. The complete array data
are available via http://www.rzpd.de/cgi-bin/services/exp/viewExpressionData.pl.cgi
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Affiliation(s)
- Kerstin Amann
- Department of Pathology, University of Erlangen-Nürnberg, Krankenhausstrasse 8-10, Erlangen D-91054, Germany.
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Shina MC, Müller R, Blau-Wasser R, Glöckner G, Schleicher M, Eichinger L, Noegel AA, Kolanus W. A cytohesin homolog in Dictyostelium amoebae. PLoS One 2010; 5:e9378. [PMID: 20186335 PMCID: PMC2826412 DOI: 10.1371/journal.pone.0009378] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 02/02/2010] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Dictyostelium, an amoeboid motile cell, harbors several paralogous Sec7 genes that encode members of three distinct subfamilies of the Sec7 superfamily of Guanine nucleotide exchange factors. Among them are proteins of the GBF/BIG family present in all eukaryotes. The third subfamily represented with three members in D. discoideum is the cytohesin family that has been thought to be metazoan specific. Cytohesins are characterized by a Sec7 PH tandem domain and have roles in cell adhesion and migration. PRINCIPAL FINDINGS Dictyostelium SecG exhibits highest homologies to the cytohesins. It harbors at its amino terminus several ankyrin repeats that are followed by the Sec7 PH tandem domain. Mutants lacking SecG show reduced cell-substratum adhesion whereas cell-cell adhesion that is important for development is not affected. Accordingly, multicellular development proceeds normally in the mutant. During chemotaxis secG(-) cells elongate and migrate in a directed fashion towards cAMP, however speed is moderately reduced. SIGNIFICANCE The data indicate that SecG is a relevant factor for cell-substrate adhesion and reveal the basic function of a cytohesin in a lower eukaryote.
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Affiliation(s)
- Maria Christina Shina
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
| | - Rolf Müller
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
| | - Rosemarie Blau-Wasser
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
| | - Gernot Glöckner
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
- Leibniz Institute for Age Research - Fritz-Lipmann-Institute e.V., Jena, Germany
| | - Michael Schleicher
- Institute of Anatomy and Cell Biology and Center for Integrated Protein Science (CIPSM), Ludwig-Maximilians-University, Muenchen, Germany
| | - Ludwig Eichinger
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
| | - Angelika A. Noegel
- Center for Biochemistry, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Köln, Germany
- * E-mail: (AAN); (WK)
| | - Waldemar Kolanus
- Laboratory of Molecular Immunology, LIMES Institute of the University of Bonn, Bonn, Germany
- * E-mail: (AAN); (WK)
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Nakagawa H, Suzuki H, Machida S, Suzuki J, Ohashi K, Jin M, Miyamoto S, Terasaki AG. Contribution of the LIM domain and nebulin-repeats to the interaction of Lasp-2 with actin filaments and focal adhesions. PLoS One 2009; 4:e7530. [PMID: 19851499 PMCID: PMC2761545 DOI: 10.1371/journal.pone.0007530] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 09/28/2009] [Indexed: 11/24/2022] Open
Abstract
Lasp-2 binds to actin filaments and concentrates in the actin bundles of filopodia and lamellipodia in neural cells and focal adhesions in fibroblastic cells. Lasp-2 has three structural regions: a LIM domain, a nebulin-repeat region, and an SH3 domain; however, the region(s) responsible for its interactions with actin filaments and focal adhesions are still unclear. In this study, we revealed that the N-terminal fragment from the LIM domain to the first nebulin-repeat module (LIM-n1) retained actin-binding activity and showed a similar subcellular localization to full-length lasp-2 in neural cells. The LIM domain fragment did not interact with actin filaments or localize to actin filament bundles. In contrast, LIM-n1 showed a clear subcellular localization to filopodial actin bundles. Although truncation of the LIM domain caused the loss of F-actin binding activity and the accumulation of filopodial actin bundles, these truncated fragments localized to focal adhesions. These results suggest that lasp-2 interactions with actin filaments are mediated through the cooperation of the LIM domain and the first nebulin-repeat module in vitro and in vivo. Actin filament binding activity may be a major contributor to the subcellular localization of lasp-2 to filopodia but is not crucial for lasp-2 recruitment to focal adhesions.
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Affiliation(s)
- Hiroyuki Nakagawa
- Division of Biology, Faculty of Science, Fukuoka University, Fukuoka, Japan.
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16
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Blau-Wasser R, Euteneuer U, Xiong H, Gassen B, Schleicher M, Noegel AA. CP250, a novel acidic coiled-coil protein of the Dictyostelium centrosome, affects growth, chemotaxis, and the nuclear envelope. Mol Biol Cell 2009; 20:4348-61. [PMID: 19692569 DOI: 10.1091/mbc.e09-03-0180] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Dictyostelium centrosome is a nucleus associated body consisting of a box-shaped core surrounded by the corona, an amorphous matrix functionally equivalent to the pericentriolar material of animal centrosomes which is responsible for the nucleation and anchoring of microtubules. Here we describe CP250 a component of the corona, an acidic coiled coil protein that is present at the centrosome throughout interphase while disappearing during prophase and reappearing at the end of late telophase. Amino acids 756-1148 of the 2110 amino acids are sufficient for centrosomal targeting and cell cycle-dependent centrosome association. Mutant cells lacking CP250 are smaller in size, growth on bacteria is delayed, chemotaxis is altered, and development is affected, which, in general, are defects observed in cytoskeletal mutants. Furthermore, loss of CP250 affected the nuclear envelope and led to reduced amounts and altered distribution of Sun-1, a conserved nuclear envelope protein that connects the centrosome to chromatin.
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Affiliation(s)
- Rosemarie Blau-Wasser
- Center for Biochemistry, Medical Faculty, University of Cologne, 50931 Köln, Germany
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Endocytosis and the Actin Cytoskeleton in Dictyostelium discoideum. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 267:343-97. [DOI: 10.1016/s1937-6448(08)00633-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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18
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A GPCR involved in post aggregation events in Dictyostelium discoideum. Dev Biol 2007; 312:29-43. [PMID: 17950724 DOI: 10.1016/j.ydbio.2007.08.055] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Revised: 08/27/2007] [Accepted: 08/28/2007] [Indexed: 02/07/2023]
Abstract
Dictyostelium has 55 genes encoding seven-transmembrane G-protein-coupled receptors (GPCR) that belong to five of the six GPCR families. GrlA is one of the 17 family 3 GPCRs in Dictyostelium all of which resemble GABA(B) receptors from higher eukaryotes. GrlA is a 90-kDa protein present on the plasma membrane and on membranes of the ER. It has a large extracellular domain with homology to bacterial periplasmic proteins. The GrlA message is present throughout development and shows increased levels during the post aggregation stages. Inactivation of the grlA gene does not severely affect the growth phase, however, it leads to a delay in the development at the post aggregation stage. GrlA deficient strains show an altered DIF-1 response specific to the prestalk-specific ecmA and ecmB gene, reduced car2 and pkaC transcript levels and form a reduced number of spores. Germination of the spores was as in wild type. Transcriptional profiling supported the defect in the sporulation pathway as a large number of genes involved in the biogenesis and organization of the extracellular matrix and the sporulation process were significantly downregulated in the mutant.
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Wender N, Villalobo E, Mirelman D. EhLimA, a novel LIM protein, localizes to the plasma membrane in Entamoeba histolytica. EUKARYOTIC CELL 2007; 6:1646-55. [PMID: 17630327 PMCID: PMC2043370 DOI: 10.1128/ec.00177-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The parasitic protozoan Entamoeba histolytica relies on a very dynamic cytoskeleton in order to invade and survive in host tissues. Identification of cytoskeletal elements is key to understanding these processes. Here we present the characterization of EhLimA, the first LIM protein of E. histolytica. EhLimA consists of a single LIM domain at its N terminus and exhibits the highest degree of homology with DdLimE from Dictyostelium discoideum. Immunofluorescence localization of EhLimA using anti-EhLimA antibodies revealed that EhLimA is highly concentrated at the plasma membrane of cells. Silencing or overexpression of the EhLimA gene did not have a significant effect on the growth or morphology of the parasite. EhLimA associates with the cytoskeleton as demonstrated by the enrichment of the protein in cytoskeleton fractions as well as in pull-down assays that revealed that cytoskeleton association involves interaction with actin. EhLimA binding to actin was shown to be dependent on the N-terminal LIM domain of EhLimA, as removal of even half of the LIM domain resulted in almost complete inhibition of the binding to actin. We also found that a portion of EhLimA floats to the lower-density regions of a sucrose gradient together with portions of the Gal-lectin light subunit and actin. Treatment of cells with the cholesterol-sequestering agent digitonin resulted in increased solubility of EhLimA. These results indicate that in addition to cytoskeletal association, EhLimA may also associate with lipid rafts in the parasite plasma membrane and suggest that EhLimA may be part of the molecular system connecting the actin cytoskeleton to membrane rafts.
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Affiliation(s)
- Nomy Wender
- Department of Biological Chemistry, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100, Israel
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20
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STATc is a key regulator of the transcriptional response to hyperosmotic shock. BMC Genomics 2007; 8:123. [PMID: 17517120 PMCID: PMC1888708 DOI: 10.1186/1471-2164-8-123] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Accepted: 05/21/2007] [Indexed: 11/14/2022] Open
Abstract
Background Dictyostelium discoideum is frequently subjected to environmental changes in its natural habitat, the forest soil. In order to survive, the organism had to develop effective mechanisms to sense and respond to such changes. When cells are faced with a hypertonic environment a complex response is triggered. It starts with signal sensing and transduction and leads to changes in cell shape, the cytoskeleton, transport processes, metabolism and gene expression. Certain aspects of the Dictyostelium osmotic stress response have been elucidated, however, no comprehensive picture was available up to now. Results To better understand the D. discoideum response to hyperosmotic conditions, we performed gene expression profiling using DNA microarrays. The transcriptional profile of cells treated with 200 mM sorbitol during a 2-hour time course revealed a time-dependent induction or repression of 809 genes, more than 15% of the genes on the array, which peaked 45 to 60 minutes after the hyperosmotic shock. The differentially regulated genes were applied to cluster analysis and functional annotation using gene GO terms. Two main responses appear to be the down-regulation of the metabolic machinery and the up-regulation of the stress response system, including STATc. Further analysis of STATc revealed that it is a key regulator of the transcriptional response to hyperosmotic shock. Approximately 20% of the differentially regulated genes were dependent on the presence of STATc. Conclusion At least two signalling pathways are activated in Dictyostelium cells subjected to hypertonicity. STATc is responsible for the transcriptional changes of one of them.
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21
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GrlJ, a Dictyostelium GABAB-like receptor with roles in post-aggregation development. BMC DEVELOPMENTAL BIOLOGY 2007; 7:44. [PMID: 17501984 PMCID: PMC1885808 DOI: 10.1186/1471-213x-7-44] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Accepted: 05/14/2007] [Indexed: 11/10/2022]
Abstract
BACKGROUND The G-protein-coupled receptor (GPCR) family represents the largest and most important group of targets for chemotherapeutics. They are extremely versatile receptors that transduce signals as diverse as biogenic amines, purins, odorants, ions and pheromones from the extracellular compartment to the interior via biochemical processes involving GTP-binding proteins. Until recently, the cyclic AMP receptors (cARs) were the only known G protein coupled receptors in Dictyostelium discoideum. The completed genome sequence revealed the presence of several families of GPCRs in Dictyostelium, among them members of the family 3 of GPCRs, the GABAB/glutamate like receptor family, which in higher eukaryotes is involved in neuronal signaling. RESULTS D. discoideum has seventeen Family 3 members of GPCRs, denoted GrlA through GrlR. Their transcripts are detected throughout development with increased levels during early and late development. We have examined here GrlJ. GFP-tagged GrlJ localises to the plasma-membrane and to internal membranes. Inactivation of the grlJ gene leads to precocious development, and the mutant completes development ~6 hours earlier. Alterations were also noted at the slug stage and in spore formation. grlJ- slugs were longer and broke apart several times on their way to culmination forming smaller but proportionate fruiting bodies. Spores from grlJ- fruiting bodies were malformed and less viable, although the spore differentiation factors were synthesized and sensed normally. Expression of a GFP-tagged full length GrlJ rescued the phenotype. CONCLUSION Our data suggest that GrlJ acts at several stages of Dictyostelium development and that it is a negative regulator in Dictyostelium development.
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22
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Adyshev DM, Kolosova IA, Verin AD. Potential protein partners for the human TIMAP revealed by bacterial two-hybrid screening. Mol Biol Rep 2007; 33:83-9. [PMID: 16817016 DOI: 10.1007/s11033-005-2311-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2005] [Indexed: 11/30/2022]
Abstract
BacterioMatch Two-Hybrid System (Stratagene) was applied in order to identify potential human TIMAP interaction proteins in the lung. TIMAP highly expressed in endothelial cells and may be involved in endothelial cytoskeletal and barrier regulation. Seven TIMAP interacting partner proteins were identified. Four of identified proteins: cystein and glycine-rich protein 1, eukaryotic translation elongation factor 2, U5 snRNP-specific protein 116 kD, and solute carrier family 3 member 2 are involved in actin cytoskeleton organization, cell adhesion or translation and transcriptional regulation.
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Affiliation(s)
- Djanybek M Adyshev
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, School of Medicine, Johns Hopkins University, 5200 Eastern Avenue, MFL Building Center Tower, Baltimore, MD 21224, USA
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Thomas C, Hoffmann C, Dieterle M, Van Troys M, Ampe C, Steinmetz A. Tobacco WLIM1 is a novel F-actin binding protein involved in actin cytoskeleton remodeling. THE PLANT CELL 2006; 18:2194-206. [PMID: 16905656 PMCID: PMC1560925 DOI: 10.1105/tpc.106.040956] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 06/22/2006] [Accepted: 07/13/2006] [Indexed: 05/05/2023]
Abstract
We used confocal microscopy and in vitro analyses to show that Nicotiana tabacum WLIM1, a LIM domain protein related to animal Cys-rich proteins, is a novel actin binding protein in plants. Green fluorescent protein (GFP)-tagged WLIM1 protein accumulated in the nucleus and cytoplasm of tobacco BY2 cells. It associated predominantly with actin cytoskeleton, as demonstrated by colabeling and treatment with actin-depolymerizing latrunculin B. High-speed cosedimentation assays revealed the ability of WLIM1 to bind directly to actin filaments with high affinity. Fluorescence recovery after photobleaching and fluorescence loss in photobleaching showed a highly dynamic in vivo interaction of WLIM1-GFP with actin filaments. Expression of WLIM1-GFP in BY2 cells significantly delayed depolymerization of the actin cytoskeleton induced by latrunculin B treatment. WLIM1 also stabilized actin filaments in vitro. Importantly, expression of WLIM1-GFP in Nicotiana benthamiana leaves induces significant changes in actin cytoskeleton organization, specifically, fewer and thicker actin bundles than in control cells, suggesting that WLIM1 functions as an actin bundling protein. This hypothesis was confirmed by low-speed cosedimentation assays and direct observation of F-actin bundles that formed in vitro in the presence of WLIM1. Taken together, these data identify WLIM1 as a novel actin binding protein that increases actin cytoskeleton stability by promoting bundling of actin filaments.
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Khurana T, Brzostowski JA, Kimmel AR. A Rab21/LIM-only/CH-LIM complex regulates phagocytosis via both activating and inhibitory mechanisms. EMBO J 2005; 24:2254-64. [PMID: 15962002 PMCID: PMC1173156 DOI: 10.1038/sj.emboj.7600716] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Accepted: 05/24/2005] [Indexed: 11/08/2022] Open
Abstract
We have identified two LIM domain proteins, LimF and ChLim, from Dictyostelium that interact with each other and with the small, Rab5-related, Rab21 GTPase to collectively regulate phagocytosis. To investigate in vivo functions, we generated cell lines that lack or overexpress LimF and ChLim and strains that express activating or inhibiting variants of Rab21. Overexpression of LimF, loss of ChLim, or expression of constitutively active Rab21 increases the rate of phagocytosis above that of wild type. Conversely, loss of LimF, overexpression of ChLim, or expression of a dominant-negative Rab21 inhibits phagocytosis. Our studies using cells carrying multiple mutations in these genes further indicate that ChLim antagonizes the activating function of Rab21-GTP during phagocytosis; in turn, LimF is required for Rab21-GTP function. Finally, we demonstrate that ChLim and LimF localize to the phagocytic cup and phago-lysosomal vesicles. We suggest that LimF, ChLim, and activated Rab21-GTP participate as a novel signaling complex that regulates phagocytic activity.
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Affiliation(s)
- Taruna Khurana
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, USA
| | - Joseph A Brzostowski
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, USA
| | - Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, NIDDK, National Institutes of Health, Bethesda, MD, USA
- Laboratory of Cellular and Developmental Biology, National Institutes of Health, NIDDK, MMDS, Building 6/B1-22, NIH, Bethesda, MD 20892-2715, USA. Tel.: +1 301 496 3016; Fax: +1 301 496 5239; E-mail:
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25
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Bosgraaf L, Waijer A, Engel R, Visser AJWG, Wessels D, Soll D, van Haastert PJM. RasGEF-containing proteins GbpC and GbpD have differential effects on cell polarity and chemotaxis in Dictyostelium. J Cell Sci 2005; 118:1899-910. [PMID: 15827084 DOI: 10.1242/jcs.02317] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The regulation of cell polarity plays an important role in chemotaxis. Previously, two proteins termed GbpC and GbpD were identified in Dictyostelium, which contain RasGEF and cyclic nucleotide binding domains. Here we show that gbpC-null cells display strongly reduced chemotaxis, because they are unable to polarise effectively in a chemotactic gradient. However, gbpD-null mutants exhibit the opposite phenotype: cells display improved chemotaxis and appear hyperpolar, because cells make very few lateral pseudopodia, whereas the leading edge is continuously remodelled. Overexpression of GbpD protein results in severely reduced chemotaxis. Cells extend many bifurcated and lateral pseudopodia, resulting in the absence of a leading edge. Furthermore, cells are flat and adhesive owing to an increased number of substrate-attached pseudopodia. This GbpD phenotype is not dependent on intracellular cGMP or cAMP, like its mammalian homolog PDZ-GEF. Previously we showed that GbpC is a high-affinity cGMP-binding protein that acts via myosin II. We conclude that cGMP activates GbpC, mediating the chemoattractant-induced establishment of cell polarity through myosin. GbpD induces the formation of substrate-attached pseudopodia, resulting in increased attachment and suppression of polarity.
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Affiliation(s)
- Leonard Bosgraaf
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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26
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Fajardo M, Schleicher M, Noegel A, Bozzaro S, Killinger S, Heuner K, Hacker J, Steinert M. Calnexin, calreticulin and cytoskeleton-associated proteins modulate uptake and growth of Legionella pneumophila in Dictyostelium discoideum. Microbiology (Reading) 2004; 150:2825-2835. [PMID: 15347742 DOI: 10.1099/mic.0.27111-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The haploid amoebaDictyostelium discoideumis a versatile host system for studying cellular aspects ofLegionellapathogenicity. Previous studies have shown that the internalization ofL. pneumophilaleads to an endoplasmic reticulum (ER)-derived organelle that supports intracellular replication of the bacteria. In this study a roadmap of host-cell factors involved in this process was developed. Phagocytosis assays with specific cellular inhibitors and the effects of well defined host-cell mutants revealed that cytoplasmic calcium levels, cytoskeleton-associated proteins and the calcium-binding proteins of the ER, calreticulin and calnexin, specifically influence the uptake and intracellular growth ofL. pneumophila. Confocal microscopic time series with green fluorescent protein (GFP)-tagged calnexin and calreticulin demonstrated the accumulation of both proteins in the phagocytic cup ofL. pneumophila-infected host cells. In contrast to the control experiment withEscherichia coli-containing phagosomes, both proteins decorated the replicative vacuole ofL. pneumophiladuring the entire growth phase of the bacteria. The cumulative effects of cytosolic calcium levels, the spatial distribution of calnexin and calreticulin, and the defective invasion and replication ofL. pneumophilain calnexin- and calreticulin-minus cells suggest that these factors are part of a regulatory system that leads to the specific vacuole ofL. pneumophila.
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Affiliation(s)
- Marcela Fajardo
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany
| | - Michael Schleicher
- Institut für Zellbiologie, Ludwig-Maximilians-Universität, Schillerstr. 42, D-80336 München, Germany
| | - Angelika Noegel
- Zentrum Biochemie, Medizinische Fakultät der Universität zu Köln, Joseph-Stelzmann-Str. 52, D-50931 Köln, Germany
| | - Salvatore Bozzaro
- Department of Clinical and Biological Sciences, University Turin, Ospedale S. Luigi, Orbassano 10043, Italy
| | - Silke Killinger
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany
| | - Klaus Heuner
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany
| | - Jörg Hacker
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany
| | - Michael Steinert
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany
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27
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Schneider N, Weber I, Faix J, Prassler J, Müller-Taubenberger A, Köhler J, Burghardt E, Gerisch G, Marriott G. A Lim protein involved in the progression of cytokinesis and regulation of the mitotic spindle. ACTA ACUST UNITED AC 2004; 56:130-9. [PMID: 14506710 DOI: 10.1002/cm.10139] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
DdLimE regulates cell motility and cytokinesis in Dictyostelium. To specify its function, we generated knock-out mutants and analyzed mitosis by marking the mitotic apparatus with GFP-alpha-tubulin. Characteristic of DdLimE-null cells is a late reversal of cytokinesis caused by backward movement of the incipient daughter cells. This process of "retro-cytokinesis" is accompanied by a delay in disassembly of the mitotic spindle. The length of interphase microtubules is increased and their depolymerization at prophase is impaired. These data indicate that DdLimE links the cortical actin network, where it is located, to the microtubule system, whose dynamics it regulates.
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Affiliation(s)
- Natalie Schneider
- University of Wisconsin-Madison, Department of Physiology, Madison, WI 53706, USA
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28
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Abstract
Cysteine-rich proteins (CRPs) have been shown to be involved in cell differentiation, transcriptional regulation and the organisation of the actin cytoskeleton. Thus far, the latter function has been inferred solely from the in vitro interaction of CRP1, CRP2, and CRP3 with alpha-actinin and zyxin. We show here that purified, recombinant CRP2 binds directly to F-actin in vitro in co-sedimentation assays. Using a green fluorescent protein (GFP)-tagged construct of CRP2 we analysed its localisation and dynamics in A7r5 rat smooth muscle cells. CRP2 was associated with the actin cytoskeleton and decorated actin stress fibres in a continuous fashion, unlike the periodic labelling pattern observed for alpha-actinin and zyxin, which also accumulate in focal adhesions. Using live video fluorescence microscopy we observed the behaviour of GFP-CRP2 during the dynamic rearrangement of the actin cytoskeleton in phorbol 12,13-dibutyrate-treated A7r5 cells. In contrast to the actin-binding proteins SM22alpha and alpha-actinin, GFP-CRP2 did not translocate into the podosomes induced by this treatment, but remained preferentially bound to the stress fibres, suggesting an actin filament-stabilising role for CRP2. When fused to the mitochondrial targeting sequence from the Listeria protein ActA, GFP-CRP2 was almost completely localised to mitochondria, but no significant recruitment of either alpha-actinin or zyxin could be observed. Taken together, our results demonstrate that CRP2 can bind to F-actin directly and that the association with the actin cytoskeleton is independent of alpha-actinin or zyxin localisation in the cell, thus questioning the role of CRP2 as a regulator of alpha-actinin function in vivo.
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Affiliation(s)
- Markus Grubinger
- Department of Cell Biology, Austrian Academy of Sciences, Billrothstrasse 11, A-5020 Salzburg, Austria.
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Mackin NA, Sousou TJ, Erdman SE. The PXL1 gene of Saccharomyces cerevisiae encodes a paxillin-like protein functioning in polarized cell growth. Mol Biol Cell 2004; 15:1904-17. [PMID: 14767053 PMCID: PMC379286 DOI: 10.1091/mbc.e04-01-0004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Saccharomyces cerevisiae open reading frame YKR090w encodes a predicted protein displaying similarity in organization to paxillin, a scaffolding protein that organizes signaling and actin cytoskeletal regulating activities in many higher eucaryotic cell types. We found that YKR090w functions in a manner analogous to paxillin as a mediator of polarized cell growth; thus, we have named this gene PXL1 (Paxillin-like protein 1). Analyses of pxl1Delta strains show that PXL1 is required for the selection and maintenance of polarized growth sites during vegetative growth and mating. Genetic analyses of strains lacking both PXL1 and the Rho GAP BEM2 demonstrate that such cells display pronounced growth defects in response to different conditions causing Rho1 pathway activation. PXL1 also displays genetic interactions with the Rho1 effector FKS1. Pxl1p may therefore function as a modulator of Rho-GTPase signaling. A GFP::Pxl1 fusion protein localizes to sites of polarized cell growth. Experiments mapping the localization determinants of Pxl1p demonstrate the existence of localization mechanisms conserved between paxillin and Pxl1p and indicate an evolutionarily ancient and conserved role for LIM domain proteins in acting to modulate cell signaling and cytoskeletal organization during polarized growth.
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Affiliation(s)
- Nancy A Mackin
- Department of Biology, Syracuse University, Syracuse, New York 13244, USA
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Rivero F, Somesh BP. Signal transduction pathways regulated by Rho GTPases in Dictyostelium. J Muscle Res Cell Motil 2003; 23:737-49. [PMID: 12952072 DOI: 10.1023/a:1024423611223] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Rho GTPases are ubiquitously expressed across the eukaryotes where they act as molecular switches, cycling between an active GTP-bound state and an inactive GDP-bound state. Activation enables Rho GTPases to interact with a multitude of effectors that relay upstream signals to cytoskeletal and other components, eliciting rearrangements of the actin cytoskeleton and diverse other cellular responses. In Dictyostelium the Rho family comprises 15 members. Some of them (Rac1a/b/c, RacF1/F2, RacB) are members of the Rac subfamily, and one, RacA, belongs to the RhoBTB subfamily, however the Rho and Cdc42 subfamilies are not represented. Dictyostelium Rho GTPases regulate actin polymerization, cell morphology, endocytosis, cytokinesis, cell polarity and chemotaxis. Guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs) modulate the activation/inactivation cycle of the GTPases. In addition, guanine nucleotide-dissociation inhibitors (GDIs) regulate cycling of the GTPases between membranes and cytosol. Members of these three classes of regulatory molecules along with some effectors have been identified in Dictyostelium during the last years and their role in Rho signaling pathways has been investigated.
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Affiliation(s)
- Francisco Rivero
- Institut für Biochemie I, Medizinische Fakultät, Universität zu Köln, Joseph-Stelzmann-Strasse 52, 50931 Köln, Germany.
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Herr C, Clemen CS, Lehnert G, Kutschkow R, Picker SM, Gathof BS, Zamparelli C, Schleicher M, Noegel AA. Function, expression and localization of annexin A7 in platelets and red blood cells: insights derived from an annexin A7 mutant mouse. BMC BIOCHEMISTRY 2003; 4:8. [PMID: 12925238 PMCID: PMC194730 DOI: 10.1186/1471-2091-4-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2003] [Accepted: 08/19/2003] [Indexed: 11/13/2022]
Abstract
BACKGROUND Annexin A7 is a Ca2+- and phospholipid-binding protein expressed as a 47 and 51 kDa isoform, which is thought to be involved in membrane fusion processes. Recently the 47 kDa isoform has been identified in erythrocytes where it was proposed to be a key component in the process of the Ca2+-dependent vesicle release, a process with which red blood cells might protect themselves against an attack by for example complement components. RESULTS The role of annexin A7 in red blood cells was addressed in erythrocytes from anxA7-/- mice. Interestingly, the Ca2+-mediated vesiculation process was not impaired. Also, the membrane organization appeared not to be disturbed as assessed using gradient fractionation studies. Instead, lack of annexin A7 led to an altered cell shape and increased osmotic resistance of red blood cells. Annexin A7 was also identified in platelets. In these cells its loss led to a slightly slower aggregation velocity which seems to be compensated by an increased number of platelets. The results appear to rule out an important role of annexin A7 in membrane fusion processes occurring in red blood cells. Instead the protein might be involved in the organization of the membrane cytoskeleton. Red blood cells may represent an appropriate model to study the role of annexin A7 in cellular processes. CONCLUSION We have demonstrated the presence of both annexin A7 isoforms in red blood cells and the presence of the small isoform in platelets. In both cell types the loss of annexin A7 impairs cellular functions. The defects observed are however not compatible with a crucial role for annexin A7 in membrane fusion processes in these cell types.
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Affiliation(s)
- Claudia Herr
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Christoph S Clemen
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Gisela Lehnert
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
| | - Rüdiger Kutschkow
- Institute for Clinical Chemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 9, 50924 Cologne, Germany
| | - Susanne M Picker
- Transfusion Medicine, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 9, 50924 Cologne, Germany
| | - Birgit S Gathof
- Transfusion Medicine, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 9, 50924 Cologne, Germany
| | - Carlotta Zamparelli
- Centro Biologia Molecolare CNR, Dipartimento di Scienze Biochimiche, Universita La Sapienza, P.le A. Moro, 5, 00185 Roma, Italy
| | - Michael Schleicher
- Institut für Zellbiologie, Ludwig-Maximilians-Universität München, Germany
| | - Angelika A Noegel
- Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne, Germany
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