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Fan T, Qu R, Jiang X, Yang Y, Sun B, Huang X, Zhou Z, Ouyang J, Zhong S, Dai J. Spatial organization and crosstalk of vimentin and actin stress fibers regulate the osteogenic differentiation of human adipose-derived stem cells. FASEB J 2020; 35:e21175. [PMID: 33205555 DOI: 10.1096/fj.202000378rr] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 10/10/2020] [Accepted: 10/26/2020] [Indexed: 12/12/2022]
Abstract
Human adipose-derived stem cells (hASCs) are ideal seed cells for tissue engineering due to their multidirectional differentiation potential. Microfilaments, microtubules, and intermediate filaments are responsible for supporting the intracellular space. Vimentin, a type III intermediate filament protein that is specifically expressed in cells of mesenchymal origin, can function as a scaffold and endow cells with tension and shear stress resistance. Actin stress fibers (ASF) act as an important physical device in stress signal transduction, providing stiffness for cells, and promoting osteogenesis. Through direct physical contact, cross-linkers, and spatial interactions, vimentin and actin networks exist as intersecting entities. Spatial interactions occur in the overlapping area of cytoskeleton subsystems, which could affect cell morphology, cell mechanics, and cell fate. However, how does the spatial organization between the cytoskeletal subsystems changed during osteogenesis, especially between vimentin and ASF, is still not understood, and its mechanism effect on cell fate remains unclear. In our study, WB experiment was used to detect the expression changes in Vimentin, ASF, and other proteins. Cells were reconstructed by three-dimensional scanning with fluorescence microscope, and the spatial thickness of vimentin and ASF cytoskeletons and the thickness of the overlapping area between them were calculated, respectively, so as to observe the spatial reorganization of vimentin and ASF in cells. Cytochalasin D (an inhibitor of actin polymerization) and vimentin upregulated/downregulated cells were used to verify the change in the spatial organization between vimentin and ASF and its influence on osteogenesis. Then, heat shock protein 27 (HSP27) was downregulated to illuminate the regulatory mechanisms of spatial organization between vimentin and ASF during osteogenesis. The amounts and the spatial positions of vimentin and actin stress fiber exhibited opposite trends during osteogenesis. Through controlling the anchor sites on the nucleus, intermediate filaments vimentin can reduce the spatial proportion of actin stress fibers, which can be regulated by HSP27. In addition, depolymerization of actin stress fibers lead to lower osteogenic differentiation ability, resulting in osteogenesis and lipogenesis existed simultaneously, that can be resisted by vimentin. Our data indicate that the spatial reorganization of vimentin and actin stress fibers is a key factor in the regulation of the differentiation state of hASCs. And their spatial overlapping area is detrimental to hASCs osteogenesis, providing a new perspective for further exploring the mechanism underlying hASCs osteogenesis.
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Affiliation(s)
- Tingyu Fan
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Rongmei Qu
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Xin Jiang
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Yuchao Yang
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China.,Central Laboratory, Southern Medical University, Guangzhou, China
| | - Bing Sun
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China.,Central Laboratory, Southern Medical University, Guangzhou, China
| | - Xiaolan Huang
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China.,Central Laboratory, Southern Medical University, Guangzhou, China
| | - Zhitao Zhou
- Central Laboratory, Southern Medical University, Guangzhou, China
| | - Jun Ouyang
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Shizhen Zhong
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
| | - Jingxing Dai
- Guangdong Provincial Key Laboratory of Medical Biomechanics &, Department of Anatomy, School of Basic Medical Science, Southern Medical University, Guangzhou, China
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Prill K, Dawson JF. Assembly and Maintenance of Sarcomere Thin Filaments and Associated Diseases. Int J Mol Sci 2020; 21:E542. [PMID: 31952119 PMCID: PMC7013991 DOI: 10.3390/ijms21020542] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/06/2020] [Accepted: 01/12/2020] [Indexed: 12/22/2022] Open
Abstract
Sarcomere assembly and maintenance are essential physiological processes required for cardiac and skeletal muscle function and organism mobility. Over decades of research, components of the sarcomere and factors involved in the formation and maintenance of this contractile unit have been identified. Although we have a general understanding of sarcomere assembly and maintenance, much less is known about the development of the thin filaments and associated factors within the sarcomere. In the last decade, advancements in medical intervention and genome sequencing have uncovered patients with novel mutations in sarcomere thin filaments. Pairing this sequencing with reverse genetics and the ability to generate patient avatars in model organisms has begun to deepen our understanding of sarcomere thin filament development. In this review, we provide a summary of recent findings regarding sarcomere assembly, maintenance, and disease with respect to thin filaments, building on the previous knowledge in the field. We highlight debated and unknown areas within these processes to clearly define open research questions.
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Affiliation(s)
| | - John F. Dawson
- Centre for Cardiovascular Investigations, Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada;
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Song L, Rijal R, Karow M, Stumpf M, Hahn O, Park L, Insall R, Schröder R, Hofmann A, Clemen CS, Eichinger L. Expression of N471D strumpellin leads to defects in the endolysosomal system. Dis Model Mech 2018; 11:dmm033449. [PMID: 30061306 PMCID: PMC6177004 DOI: 10.1242/dmm.033449] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 07/09/2018] [Indexed: 12/11/2022] Open
Abstract
Hereditary spastic paraplegias (HSPs) are genetically diverse and clinically characterised by lower limb weakness and spasticity. The N471D and several other point mutations of human strumpellin (Str; also known as WASHC5), a member of the Wiskott-Aldrich syndrome protein and SCAR homologue (WASH) complex, have been shown to cause a form of HSP known as spastic paraplegia 8 (SPG8). To investigate the molecular functions of wild-type (WT) and N417D Str, we generated Dictyostelium Str- cells and ectopically expressed StrWT-GFP or StrN471D-GFP in Str- and WT cells. Overexpression of both proteins apparently caused a defect in cell division, as we observed a clear increase in multinucleate cells. Real-time PCR analyses revealed no transcriptional changes in WASH complex subunits in Str- cells, but western blots showed a twofold decrease in the SWIP subunit. GFP-trap experiments in conjunction with mass-spectrometric analysis revealed many previously known, as well as new, Str-interacting proteins, and also proteins that no longer bind to StrN471D At the cellular level, Str- cells displayed defects in cell growth, phagocytosis, macropinocytosis, exocytosis and lysosomal function. Expression of StrWT-GFP in Str- cells rescued all observed defects. In contrast, expression of StrN471D-GFP could not rescue lysosome morphology and exocytosis of indigestible material. Our results underscore a key role for the WASH complex and its core subunit, Str, in the endolysosomal system, and highlight the fundamental importance of the Str N471 residue for maintaining lysosome morphology and dynamics. Our data indicate that the SPG8-causing N471D mutation leads to a partial loss of Str function in the endolysosomal system. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Lin Song
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Ramesh Rijal
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
- Department of Biology, Texas A&M University, College Station, TX 3258, USA
| | - Malte Karow
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Maria Stumpf
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
| | - Oliver Hahn
- Max Planck Institute for Biology of Ageing, Biological Mechanisms of Ageing, 50931 Cologne, Germany
| | - Laura Park
- CR-UK Beatson Institute, Institute of Cancer Sciences, Glasgow University, Glasgow G12 8QQ, UK
| | - Robert Insall
- CR-UK Beatson Institute, Institute of Cancer Sciences, Glasgow University, Glasgow G12 8QQ, UK
| | - Rolf Schröder
- Institute of Neuropathology, University Hospital Erlangen, 91054 Erlangen, Germany
| | - Andreas Hofmann
- Structural Chemistry Program, Eskitis Institute, Griffith University, N75 Don Young Road, Nathan, QLD 4111, Australia
- Faculty of Veterinary Science, The University of Melbourne, Parkville, VIC 3030, Australia
| | - Christoph S Clemen
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Ludwig Eichinger
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, 50931 Cologne, Germany
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Augustine SM, Cherian AV, Syamaladevi DP, Subramonian N. Erianthus arundinaceus HSP70 (EaHSP70) Acts as a Key Regulator in the Formation of Anisotropic Interdigitation in Sugarcane (Saccharum spp. hybrid) in Response to Drought Stress. PLANT & CELL PHYSIOLOGY 2015; 56:2368-80. [PMID: 26423958 DOI: 10.1093/pcp/pcv142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/22/2015] [Indexed: 05/07/2023]
Abstract
Plant growth during abiotic stress is a long sought-after trait especially in crop plants in the context of global warming and climate change. Previous studies on leaf epidermal cells have revealed that during normal growth and development, adjacent cells interdigitate anisotropically to form cell morphological patterns known as interlocking marginal lobes (IMLs), involving the cell wall-cell membrane-cortical actin continuum. IMLs are growth-associated cell morphological changes in which auxin-binding protein (ABP), Rho GTPases and actin are known to play important roles. In the present study, we investigated the formation of IMLs under drought stress and found that Erianthus arundinaceus, a drought-tolerant wild relative of sugarcane, develops such growth-related cell morphological patterns under drought stress. Using confocal microscopy, we showed an increasing trend in cortical F-actin intensity in drought-tolerant plants with increasing soil moisture stress. In order to check the role of drought tolerance-related genes in IML formation under soil moisture stress, we adopted a structural data mining strategy and identified indirect connections between the ABPs and heat shock proteins (HSPs). Initial experimental evidence for this connection comes from the high transcript levels of HSP70 observed in drought-stressed Erianthus, which developed anisotropic interdigitation, i.e. IMLs. Subsequently, by overexpressing the E. arundinaceus HSP70 gene (EaHSP70) in sugarcane (Saccharum spp. hybrid), we confirm the role of HSP70 in the formation of anisotropic interdigitation under drought stress. Taken together, our results suggest that EaHSP70 acts as a key regulator in the formation of anisotropic interdigitation in drought-tolerant plants (Erianthus and HSP70 transgenic sugarcane) under moisture stress in an actin-mediated pathway. The possible biological significance of the formation of drought-associated interlocking marginal lobes (DaIMLs) in sugarcane plants upon drought stress is discussed.
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Affiliation(s)
| | - Anoop V Cherian
- Present address: Max Planck Institute for Heart and Lungs Research, Bad Nauheim, Germany.
| | - Divya P Syamaladevi
- Sugarcane Breeding Institute, ICAR, Coimbatore 641007, India Present address: Indian Institute of Rice Research, ICAR, Hyderabad, India.
| | - N Subramonian
- Sugarcane Breeding Institute, ICAR, Coimbatore 641007, India
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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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Omosigho NN, Swaminathan K, Plomann M, Müller-Taubenberger A, Noegel AA, Riyahi TY. The Dictyostelium discoideum RACK1 orthologue has roles in growth and development. Cell Commun Signal 2014; 12:37. [PMID: 24930026 PMCID: PMC4094278 DOI: 10.1186/1478-811x-12-37] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 06/06/2014] [Indexed: 12/19/2022] Open
Abstract
Background The receptor for activated C-kinase 1 (RACK1) is a conserved protein belonging to the WD40 repeat family of proteins. It folds into a beta propeller with seven blades which allow interactions with many proteins. Thus it can serve as a scaffolding protein and have roles in several cellular processes. Results We identified the product of the Dictyostelium discoideum gpbB gene as the Dictyostelium RACK1 homolog. The protein is mainly cytosolic but can also associate with cellular membranes. DdRACK1 binds to phosphoinositides (PIPs) in protein-lipid overlay and liposome-binding assays. The basis of this activity resides in a basic region located in the extended loop between blades 6 and 7 as revealed by mutational analysis. Similar to RACK1 proteins from other organisms DdRACK1 interacts with G protein subunits alpha, beta and gamma as shown by yeast two-hybrid, pulldown, and immunoprecipitation assays. Unlike the Saccharomyces cerevisiae and Cryptococcus neoformans RACK1 proteins it does not appear to take over Gβ function in D. discoideum as developmental and other defects were not rescued in Gβ null mutants overexpressing GFP-DdRACK1. Overexpression of GFP-tagged DdRACK1 and a mutant version (DdRACK1mut) which carried a charge-reversal mutation in the basic region in wild type cells led to changes during growth and development. Conclusion DdRACK1 interacts with heterotrimeric G proteins and can through these interactions impact on processes specifically regulated by these proteins.
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Affiliation(s)
| | | | | | | | - Angelika A Noegel
- Institute of Biochemistry I, Medical Faculty, Center for Molecular Medicine Cologne (CMMC) and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, 50931 Köln, Germany.
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Hishiya A, Kitazawa T, Takayama S. BAG3 and Hsc70 interact with actin capping protein CapZ to maintain myofibrillar integrity under mechanical stress. Circ Res 2010; 107:1220-31. [PMID: 20884878 DOI: 10.1161/circresaha.110.225649] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
RATIONALE A homozygous disruption or genetic mutation of the bag3 gene, a member of the Bcl-2-associated athanogene (BAG) family proteins, causes cardiomyopathy and myofibrillar myopathy that is characterized by myofibril and Z-disc disruption. However, the detailed disease mechanism is not yet fully understood. OBJECTIVE bag3(-/-) mice exhibit differences in the extent of muscle degeneration between muscle groups with muscles experiencing the most usage degenerating at an accelerated rate. Usage-dependent muscle degeneration suggests a role for BAG3 in supporting cytoskeletal connections between the Z-disc and myofibrils under mechanical stress. The mechanism by which myofibrillar structure is maintained under mechanical stress remains unclear. The purpose of the study is to clarify the detailed molecular mechanism of BAG3-mediated muscle maintenance under mechanical stress. METHODS AND RESULTS To address the question of whether bag3 gene knockdown induces myofibrillar disorganization caused by mechanical stress, in vitro mechanical stretch experiments using rat neonatal cardiomyocytes and a short hairpin RNA-mediated gene knockdown system of the bag3 gene were performed. As expected, mechanical stretch rapidly disrupts myofibril structures in bag3 knockdown cardiomyocytes. BAG3 regulates the structural stability of F-actin through the actin capping protein, CapZβ1, by promoting association between Hsc70 and CapZβ1. BAG3 facilitates the distribution of CapZβ1 to the proper location, and dysfunction of BAG3 induces CapZ ubiquitin-proteasome-mediated degradation. Inhibition of CapZβ1 function by overexpressing CapZβ2 increased myofibril vulnerability and fragmentation under mechanical stress. On the other hand, overexpression of CapZβ1 inhibits myofibrillar disruption in bag3 knockdown cells under mechanical stress. As a result, heart muscle isolated from bag3(-/-) mice exhibited myofibrillar degeneration and lost contractile activity after caffeine contraction. CONCLUSIONS These results suggest novel roles for BAG3 and Hsc70 in stabilizing myofibril structure and inhibiting myofibrillar degeneration in response to mechanical stress. These proteins are possible targets for further research to identify therapies for myofibrillar myopathy or other degenerative diseases.
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Affiliation(s)
- Akinori Hishiya
- Boston Biomedical Research Institute, Watertown, MA 02472, USA
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Woschnagg C, Forsberg J, Engström Å, Odreman F, Venge P, Garcia RC. The Human Eosinophil Proteome. Changes Induced by Birch Pollen Allergy. J Proteome Res 2009; 8:2720-32. [DOI: 10.1021/pr800984e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Charlotte Woschnagg
- Department of Medical Sciences, Clinical Chemistry, Uppsala University, 75185 Uppsala, Sweden, Department of Medical Biochemistry and Microbiology, Uppsala University, P.O. Box 582, 75123 Uppsala, Sweden, and Leukocyte Biology and Proteomics Groups, International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
| | - Jens Forsberg
- Department of Medical Sciences, Clinical Chemistry, Uppsala University, 75185 Uppsala, Sweden, Department of Medical Biochemistry and Microbiology, Uppsala University, P.O. Box 582, 75123 Uppsala, Sweden, and Leukocyte Biology and Proteomics Groups, International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
| | - Åke Engström
- Department of Medical Sciences, Clinical Chemistry, Uppsala University, 75185 Uppsala, Sweden, Department of Medical Biochemistry and Microbiology, Uppsala University, P.O. Box 582, 75123 Uppsala, Sweden, and Leukocyte Biology and Proteomics Groups, International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
| | - Federico Odreman
- Department of Medical Sciences, Clinical Chemistry, Uppsala University, 75185 Uppsala, Sweden, Department of Medical Biochemistry and Microbiology, Uppsala University, P.O. Box 582, 75123 Uppsala, Sweden, and Leukocyte Biology and Proteomics Groups, International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
| | - Per Venge
- Department of Medical Sciences, Clinical Chemistry, Uppsala University, 75185 Uppsala, Sweden, Department of Medical Biochemistry and Microbiology, Uppsala University, P.O. Box 582, 75123 Uppsala, Sweden, and Leukocyte Biology and Proteomics Groups, International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
| | - Rodolfo C. Garcia
- Department of Medical Sciences, Clinical Chemistry, Uppsala University, 75185 Uppsala, Sweden, Department of Medical Biochemistry and Microbiology, Uppsala University, P.O. Box 582, 75123 Uppsala, Sweden, and Leukocyte Biology and Proteomics Groups, International Centre for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, 34012 Trieste, Italy
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Sultana H, Neelakanta G, Eichinger L, Rivero F, Noegel AA. Microarray phenotyping places cyclase associated protein CAP at the crossroad of signaling pathways reorganizing the actin cytoskeleton in Dictyostelium. Exp Cell Res 2009; 315:127-40. [DOI: 10.1016/j.yexcr.2008.10.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 08/29/2008] [Accepted: 10/14/2008] [Indexed: 01/31/2023]
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Masoudi AA, Uchida K, Yokouchi K, Ohwada K, Abbasi AR, Tsuji T, Watanabe T, Hirano T, Sugimoto Y, Kunieda T. Linkage mapping of the locus responsible for forelimb-girdle muscular anomaly of Japanese black cattle on bovine chromosome 26. Anim Genet 2008; 39:46-50. [PMID: 18254734 DOI: 10.1111/j.1365-2052.2007.01679.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Forelimb-girdle muscular anomaly is an autosomal recessive disorder of Japanese black cattle characterized by tremor, astasia and abnormal shape of the shoulders. Pathological examination of affected animals reveals hypoplasia of forelimb-girdle muscles with reduced diameter of muscle fibres. To identify the gene responsible for this disorder, we performed linkage mapping of the disorder locus using an inbred pedigree including a great-grand sire, a grand sire, a sire and 26 affected calves obtained from a herd of Japanese black cattle. Two hundred and fifty-eight microsatellite markers distributed across the genome were genotyped across the pedigree. Four markers on the middle region of bovine chromosome 26 showed significant linkage with the disorder locus. Haplotype analysis using additional markers in this region refined the critical region of the disorder locus to a 3.5-Mb interval on BTA26 between BM4505 and MOK2602. Comparative mapping data revealed several potential candidate genes for the disorder, including NRAP, PDZD8 and HSPA12A, which are associated with muscular function.
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Affiliation(s)
- A A Masoudi
- Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
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Chen Q, Lakshmikanth GS, Spudich JA, De Lozanne A. The localization of inner centromeric protein (INCENP) at the cleavage furrow is dependent on Kif12 and involves interactions of the N terminus of INCENP with the actin cytoskeleton. Mol Biol Cell 2007; 18:3366-74. [PMID: 17567958 PMCID: PMC1951774 DOI: 10.1091/mbc.e06-10-0895] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The inner centromeric protein (INCENP) and other chromosomal passenger proteins are known to localize on the cleavage furrow and to play a role in cytokinesis. However, it is not known how INCENP localizes on the furrow or whether this localization is separable from that at the midbody. Here, we show that the association of Dictyostelium INCENP (DdINCENP) with the cortex of the cleavage furrow involves interactions with the actin cytoskeleton and depends on the presence of the kinesin-6-related protein Kif12. We found that Kif12 is found on the central spindle and the cleavage furrow during cytokinesis. Kif12 is not required for the redistribution of DdINCENP from centromeres to the central spindle. However, in the absence of Kif12, DdINCENP fails to localize on the cleavage furrow. Domain analysis indicates that the N terminus of DdINCENP is necessary and sufficient for furrow localization and that it binds directly to the actin cytoskeleton. Our data suggest that INCENP moves from the central spindle to the furrow of a dividing cell by a Kif12-dependent pathway. Once INCENP reaches the equatorial cortex, it associates with the actin cytoskeleton where it then concentrates toward the end of cytokinesis.
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Affiliation(s)
- Qian Chen
- *Section of Molecular Cell and Developmental Biology and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712; and
| | | | - James A. Spudich
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Arturo De Lozanne
- *Section of Molecular Cell and Developmental Biology and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712; and
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Lima SB, Cenedeze MA, Bertolla RP, Filho PAH, Oehninger S, Cedenho AP. Expression of the HSPA2 gene in ejaculated spermatozoa from adolescents with and without varicocele. Fertil Steril 2006; 86:1659-63. [DOI: 10.1016/j.fertnstert.2006.05.030] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 05/08/2006] [Accepted: 05/08/2006] [Indexed: 10/24/2022]
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Koch KV, Reinders Y, Ho TH, Sickmann A, Gräf R. Identification and isolation of Dictyostelium microtubule-associated protein interactors by tandem affinity purification. Eur J Cell Biol 2006; 85:1079-90. [PMID: 16782229 DOI: 10.1016/j.ejcb.2006.05.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Tandem affinity purification (TAP) is a method originally established in yeast to isolate highly purified protein complexes in a very gentle and efficient way. In this work, we have modified TAP for Dictyostelium applications and have proved it as a useful method to specifically isolate and identify microtubule-associated protein (MAP) complexes. MAPs are known to interact with other proteins to fulfill their complex functions in balancing the dynamic instability of microtubules as well as anchoring microtubules at the cell cortex, controlling mitosis at the centrosome and guiding transport along them. DdEB1 and the Dictyostelium member of the XMAP215 protein family, DdCP224, are known to be part of complexes at the microtubule tips as well as at the centrosome. Employing TAP and mass spectrometry we were able to prove an interaction between EB1 and the DdCP224. Additionally, among other interactions that remain to be confirmed by other methods, an interaction between DdCP224 and a TACC-family protein could be shown for the first time in Dictyostelium and was confirmed by colocalization and co-immunoprecipitation analyses.
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Affiliation(s)
- Katrin V Koch
- Adolf-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, Schillerstrasse 42, D-80336 München, Germany
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Heintzelman MB. Cellular and Molecular Mechanics of Gliding Locomotion in Eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 251:79-129. [PMID: 16939778 DOI: 10.1016/s0074-7696(06)51003-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Gliding is a form of substrate-dependent cell locomotion exploited by a variety of disparate cell types. Cells may glide at rates well in excess of 1 microm/sec and do so without the gross distortion of cellular form typical of amoeboid crawling. In the absence of a discrete locomotory organelle, gliding depends upon an assemblage of molecules that links cytoplasmic motor proteins to the cell membrane and thence to the appropriate substrate. Gliding has been most thoroughly studied in the apicomplexan parasites, including Plasmodium and Toxoplasma, which employ a unique assortment of proteins dubbed the glideosome, at the heart of which is a class XIV myosin motor. Actin and myosin also drive the gliding locomotion of raphid diatoms (Bacillariophyceae) as well as the intriguing form of gliding displayed by the spindle-shaped cells of the primitive colonial protist Labyrinthula. Chlamydomonas and other flagellated protists are also able to abandon their more familiar swimming locomotion for gliding, during which time they recruit a motility apparatus independent of that driving flagellar beating.
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Affiliation(s)
- Matthew B Heintzelman
- Department of Biology, Program in Cell Biology and Biochemistry, Bucknell University, Lewisburg, PA 17837, USA
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15
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Arifuzzaman M, Oshima T, Mori H. The ATPase domain of HscC (DnaK homolog) is essential for interfering sigma70 activity in E. coli. FEMS Microbiol Lett 2004; 230:99-104. [PMID: 14734171 DOI: 10.1016/s0378-1097(03)00863-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
HscC, a DnaK homolog in Escherichia coli, consists of adenosine triphosphatase (ATPase), substrate-binding and C-terminal domains. Overexpression of HscC markedly inhibits growth of host cell and reduces the sigma(70)-dependent promoter activity presumably by forming a complex with sigma(70). To identify the region(s) of HscC responsible for growth inhibition and complex formation with sigma(70), domain swapping experiments were carried out between DnaK and HscC. Thus the chimeric proteins carrying the ATPase domain of HscC and substrate-binding domains of either HscC or DnaK were found to inhibit the growth of the cell, reduce the sigma(70)-dependent promoter activity and form a complex with sigma(70). These results indicate that the ATPase domain of HscC rather than the substrate-binding domain is important for determining its functional specificity.
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Affiliation(s)
- Mohammad Arifuzzaman
- Department of Cell Biology, NARA Institute of Science and Technology, Ikoma, Japan
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16
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Abstract
The interaction of particles with certain cell surface receptors initiates intracellular signalling pathways that ultimately lead to submembranous actin filament assembly, pseudopod extension, and the ingestion of the particles. Here, Steven Greenberg reviews recent evidence implicating various signalling events in phagocytosis--in particular, activation of tyrosine kinases and phosphatidylinositol 3-kinase--and speculates how they might regulate the actin cytoskeleton.
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Affiliation(s)
- S Greenberg
- Dept of Medicine, Pulmonary Division, Columbia University College of Physicians & Surgeons, 630 West 168th Street, New York, NY 10032, USA
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17
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Wolucka BA, Van Montagu M. GDP-mannose 3',5'-epimerase forms GDP-L-gulose, a putative intermediate for the de novo biosynthesis of vitamin C in plants. J Biol Chem 2003; 278:47483-90. [PMID: 12954627 DOI: 10.1074/jbc.m309135200] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Despite its importance for agriculture, bioindustry, and nutrition, the fundamental process of L-ascorbic acid (vitamin C) biosynthesis in plants is not completely elucidated, and little is known about its regulation. The recently identified GDP-Man 3',5'-epimerase catalyzes a reversible epimerization of GDP-D-mannose that precedes the committed step in the biosynthesis of vitamin C, resulting in the hydrolysis of the highly energetic glycosyl-pyrophosphoryl linkage. Here, we characterize the native and recombinant GDP-Man 3',5'-epimerase of Arabidopsis thaliana. GDP and GDP-D-glucose are potent competitive inhibitors of the enzyme, whereas GDP-L-fucose gives a complex type of inhibition. The epimerase contains a modified version of the NAD binding motif and is inhibited by NAD(P)H and stimulated by NAD(P)+. A feedback inhibition of vitamin C biosynthesis is observed apparently at the level of GDP-Man 3',5'-epimerase. The epimerase catalyzes at least two distinct epimerization reactions and releases, besides the well known GDP-l-galactose, a novel intermediate: GDP-L-gulose. The yield of the epimerization varies and seems to depend on the molecular form of the enzyme. Both recombinant and native enzymes co-purified with a Hsp70 heat-shock protein (Escherichia coli DnaK and A. thaliana Hsc70.3, respectively). We speculate, therefore, that the Hsp70 molecular chaperones might be involved in folding and/or regulation of the epimerase. In summary, the plant epimerase undergoes a complex regulation and could control the carbon flux into the vitamin C pathway in response to the redox state of the cell, stress conditions, and GDP-sugar demand for the cell wall/glycoprotein biosynthesis. Exogenous L-gulose and L-gulono-1,4-lactone serve as direct precursors of l-ascorbic acid in plant cells. We propose an L-gulose pathway for the de novo biosynthesis of vitamin C in plants.
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Affiliation(s)
- Beata A Wolucka
- Department of Molecular Microbiology, Flanders Interuniversity Institute for Biotechnology (VIB), Kasteelpark Arenberg 31, B-3001 Leuven-Heverlee, Belgium.
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18
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Huang S, Blanchoin L, Kovar DR, Staiger CJ. Arabidopsis capping protein (AtCP) is a heterodimer that regulates assembly at the barbed ends of actin filaments. J Biol Chem 2003; 278:44832-42. [PMID: 12947123 DOI: 10.1074/jbc.m306670200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The precise regulation of actin filament polymerization and depolymerization is essential for many cellular processes and is choreographed by a multitude of actin-binding proteins (ABPs). In higher plants the number of well characterized ABPs is quite limited, and some evidence points to significant differences in the biochemical properties of apparently conserved proteins. Here we provide the first evidence for the existence and biochemical properties of a heterodimeric capping protein from Arabidopsis thaliana (AtCP). The purified recombinant protein binds to actin filament barbed ends with Kd values of 12-24 nM, as assayed both kinetically and at steady state. AtCP prevents the addition of profilin actin to barbed ends during a seeded elongation reaction and suppresses dilution-mediated depolymerization. It does not, however, sever actin filaments and does not have a preference for the source of actin. During assembly from Mg-ATP-actin monomers, AtCP eliminates the initial lag period for actin polymerization and increases the maximum rate of polymerization. Indeed, the efficiency of actin nucleation of 0.042 pointed ends created per AtCP polypeptide compares favorably with mouse CapZ, which has a maximal nucleation of 0.17 pointed ends per CapZ polypeptide. AtCP activity is not affected by calcium but is sensitive to phosphatidylinositol 4,5-bisphosphate. We propose that AtCP is a major regulator of actin dynamics in plant cells that, together with abundant profilin, is responsible for maintaining a large pool of actin subunits and a surprisingly small population of F-actin.
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Affiliation(s)
- Shanjin Huang
- Department of Biological Sciences and Purdue Motility Group, Purdue University, West Lafayette, Indiana 47907-2064, USA
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19
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Xiang W, Rensing L. Changes in cell morphology and actin organization during heat shock in Dictyostelium discoideum: does HSP70 play a role in acquired thermotolerance? FEMS Microbiol Lett 1999; 178:95-107. [PMID: 10483728 DOI: 10.1111/j.1574-6968.1999.tb13764.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In response to heat shock (34 degrees C, 30 min), cell morphology and actin organization in Dictyostelium discoideum are drastically changed. Loss of pseudopodia and disappearance of F-actin-containing structures were observed by using fluorescence microscopy. These changes were paralleled by a rapid decrease of the F-actin content measured by a TRITC-phalloidin binding assay. The effects of heat shock on cell morphology and actin organization are transient: After heat shock (34 degrees C) or during a long-term heat treatment (30 degrees C), cell morphology, F-actin patterns and F-actin content recovered/adapted to a state which is characteristic for untreated cells. Because F-actin may be stabilized by increased amounts of heat shock proteins, their response and interaction with F-actin was analyzed. After a 1 h heat treatment (34 degrees C), the major heat shock protein of D. discoideum (HSP70) showed maximally increased synthesis rates and levels. During recovery from a 34 degrees C shock or during a continuous heat treatment at 30 degrees C, the HSP70 content first increased and then declined slowly toward normal levels. Pre-treatment of cells with a short heat shock of 30 min at 34 degrees C stabilized the F-actin content when the cells were exposed to a second heat shock. Furthermore, a transient colocalization of HSP70 and actin was observed at the beginning of heat treatment (30 degrees C) using immunological detection of HSP70 in the cytoskeletal actin fraction.
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Affiliation(s)
- W Xiang
- Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen, Germany
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20
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Moerman AM, de Maria AC, Gomes SL, Klein C. Heat shock alters poly(A) tail length of Dictyostelium discoideum hsp32 RNA. DNA Cell Biol 1998; 17:635-41. [PMID: 9703022 DOI: 10.1089/dna.1998.17.635] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hsp32 is a heat shock gene in D. discoideum. We have previously observed that heat stress-induced change produces a broad band on Northern blots, suggesting that more than one population of mRNA is present under those conditions. This was not the result of a defect in the splicing of the hsp32 mRNA, nor did it result from the use of a different transcription start site under heat shock conditions. Here, we show that the broad banding pattern reflects the appearance of a transcript with a poly(A) tail that is approximately 100 nt longer than that seen in unstressed cells. Experiments indicated that this tail was not a property of newly synthesized mRNA but rather a response to heat stress. This response appeared to be specific to the hsp32 transcript and did not result in the retention of the RNA in the nucleus. These results document a relatively unusual heat shock response and also indicate that the nature of the response differs among RNAs and has selective consequences.
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Affiliation(s)
- A M Moerman
- E.A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, MO 63104, USA
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21
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Tardieux I, Baines I, Mossakowska M, Ward GE. Actin-binding proteins of invasive malaria parasites and the regulation of actin polymerization by a complex of 32/34-kDa proteins associated with heat shock protein 70kDa. Mol Biochem Parasitol 1998; 93:295-308. [PMID: 9662713 DOI: 10.1016/s0166-6851(98)00044-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Movement of the malaria parasite into a host erythrocyte during invasion is thought to involve polymerization of parasite actin. We have used F-actin affinity chromatography to isolate actin-binding proteins from Plasmodium knowlesi merozoites, in an attempt to identify proteins responsible for regulating parasite actin polymerization during invasion. Five major proteins, of molecular masses 75, 70, 48, 40 and 34 kDa, were reproducibly eluted from the F-actin columns. The 70 kDa actin-binding protein was identified by tryptic peptide microsequencing as heat shock protein-70 kDa (HSC70); this identification was confirmed by Western blotting with anti-HSC70 antibody, and binding of the protein to ATP-agarose. A doublet of 32/34-kDa proteins coeluted with parasite HSC70 from the F-actin and ATP-agarose columns; a complex of these three proteins was also observed by gel filtration chromatography Highly enriched fractions containing the Plasmodium HSC70/32/34 complex inhibited the polymerization of rabbit skeletal muscle actin, in vitro. This capping activity was calcium-independent, and abrogated by phosphatidylinositol 4,5-bisphosphate. The average length of the actin filaments polymerized in presence of the HSC70/32/34-kDa complex was significantly shorter than in the absence of the complex, consistent with a capping activity. The capping or uncapping of actin filament ends by the HSC70/32/34-kDa complex during invasion could provide a mechanism for localized actin filament growth and movement of the parasite into the host cell.
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Affiliation(s)
- I Tardieux
- Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda 20892, USA.
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22
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Eddy RJ, Han J, Condeelis JS. Capping protein terminates but does not initiate chemoattractant-induced actin assembly in Dictyostelium. J Cell Biol 1997; 139:1243-53. [PMID: 9382870 PMCID: PMC2140204 DOI: 10.1083/jcb.139.5.1243] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/1997] [Revised: 09/25/1997] [Indexed: 02/05/2023] Open
Abstract
The first step in the directed movement of cells toward a chemotactic source involves the extension of pseudopods initiated by the focal nucleation and polymerization of actin at the leading edge of the cell. We have previously isolated a chemoattractant-regulated barbed-end capping activity from Dictyostelium that is uniquely associated with capping protein, also known as cap32/34. Although uncapping of barbed ends by capping protein has been proposed as a mechanism for the generation of free barbed ends after stimulation, in vitro and in situ analysis of the association of capping protein with the actin cytoskeleton after stimulation reveals that capping protein enters, but does not exit, the cytoskeleton during the initiation of actin polymerization. Increased association of capping protein with regions of the cell containing free barbed ends as visualized by exogenous rhodamine-labeled G-actin is also observed after stimulation. An approximate threefold increase in the number of filaments with free barbed ends is accompanied by increases in absolute filament number, whereas the average filament length remains constant. Therefore, a mechanism in which preexisting filaments are uncapped by capping protein, in response to stimulation leading to the generation of free barbed ends and filament elongation, is not supported. A model for actin assembly after stimulation, whereby free barbed ends are generated by either filament severing or de novo nucleation is proposed. In this model, exposure of free barbed ends results in actin assembly, followed by entry of free capping protein into the actin cytoskeleton, which acts to terminate, not initiate, the actin polymerization transient.
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Affiliation(s)
- R J Eddy
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461, USA
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23
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DiNubile MJ, Huang S. High concentrations of phosphatidylinositol-4,5-bisphosphate may promote actin filament growth by three potential mechanisms: inhibiting capping by neutrophil lysates, severing actin filaments and removing capping protein-beta2 from barbed ends. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1358:261-78. [PMID: 9366258 DOI: 10.1016/s0167-4889(97)00076-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cell locomotion requires rapid growth of cortical actin filaments whose barbed ends are capped in the resting cell. Phosphatidylinositol-4,5-bisphosphate (PIP2) may play a critical role as an intracellular messenger in cytoskeletal rearrangement after stimulation. We have examined the effects of PIP2 micelles on the Ca2+-independent actin filament capping activity in high speed supernatants of neutrophil lysates which we had previously demonstrated to be almost entirely due to capping protein-beta2, a homologue of cap Z. High concentrations of PIP2 totally prevented the capping of exogenous spectrin-F-actin seeds by dilute supernatants of neutrophil extracts. Capping could also be inhibited, albeit less effectively, by PIP and PI, but not by other phospholipids. When incubated with filaments in the absence of supernatant, PIP2 increased the number of growing ends. PIP2 also uncapped previously capped actin filaments, as demonstrated by incubating supernatant-capped and uncapped seeds with and without PIP2 and then comparing the initial elongation rates after addition of pyrenyl-G-actin. Incubation of capped seeds with high concentrations of PIP2 increased the number of free barbed ends to a level comparable to that of the uncapped seeds exposed to PIP2. PIP2 caused uncapping to occur too quickly to be explained simply by the off-rate of capping protein-beta2, implying that PIP2 interacted directly with capping protein on the filament ends. In fact, PIP2 transiently uncapped capped seeds in the presence of excess free capping protein. From our data, we estimate that millimolar concentrations of PIP2 (almost 100-fold higher than the amount predicted from the effective concentration in purified systems) would be required to inhibit all the capping protein-beta2 in the cytosol. This discrepancy probably results, in large part, from sequestration of PIP2 by other PIP2-binding proteins in the cytoplasm. If PIP2 mediates differential cytoskeletal growth after chemoattractant stimulation in vivo, very high concentrations may be required subjacent to the plasma membrane for regional severing and uncapping of actin filaments to occur quickly near the perturbed membrane.
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Affiliation(s)
- M J DiNubile
- Department of Medicine, Cooper Hospital / University Medical Center, UMDNJ / Robert Wood Johnson Medical School, Camden, NJ, USA.
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Benoff S, Hurley IR, Barcia M, Mandel FS, Cooper GW, Hershlag A. A potential role for cadmium in the etiology of varicocele-associated infertility. Fertil Steril 1997; 67:336-47. [PMID: 9022613 DOI: 10.1016/s0015-0282(97)81921-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To determine whether mannose ligand receptor and acrosome reaction deficits in sperm from men with varicocele are related to the transition metal content of their semen. DESIGN Cadmium and zinc in semen and blood plasma were assayed for fertile males, men without varicocele who required intracytoplasmic sperm injection to achieve fertilization, and men evaluated for potential varicocele-associated infertility. The relationship between actin cytoskeletal distributions and acrosome status was determined for fertile donor sperm in the presence and absence of exogenous cadmium. SETTING University hospital-based molecular biology research laboratory. PATIENT(S) Patients from two university hospital-based IVF-assisted reproductive technology programs and two male urology private practices. INTERVENTION(S) Fertile donor sperm were exposed to exogenous cadmium during capacitating incubations followed by culture at temperatures up to 41 degrees C. MAIN OUTCOME MEASURE(S) Metal ion levels in semen and blood plasma were determined by graphite furnace atomic absorption spectroscopy. Motile sperm were examined for mannose ligand binding and the ability to undergo spontaneous and induced acrosome reactions. Unfixed, Triton-permeabilized sperm were probed with antiactin and antimyosin antibodies. RESULT(S) Cadmium was elevated and zinc was decreased in the seminal plasma of men with varicocele. The content of these metals in semen and blood was not correlated. Cadmium exposure in vitro reduced mannose receptor expression, acrosome exocytosis, and cytoskeletal formation by fertile donor sperm. CONCLUSION(S) Defects in transition metal regulation or excessive cadmium exposure are involved in varicocele-associated infertility.
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Affiliation(s)
- S Benoff
- North Shore University Hospital, Boas-Marks Biomedical Science Research Center, New York 11030, USA
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25
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Abstract
Molecular chaperones of the 70-kilodalton heat shock protein (Hsp70) class bind to partially unfolded polypeptide substrates and participate in a wide variety of cellular processes. Differences in peptide-binding specificity among Hsp70s have led to the hypothesis that peptide binding determines specific Hsp70 functions. Protein domains were identified that were required for two separate functions of a yeast Hsp70 family. The peptide-binding domain was not required for either of these specific Hsp70 functions, which suggests that peptide-binding specificity plays little or no role in determining Hsp70 functions in vivo.
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Affiliation(s)
- P James
- Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI 53706, USA.
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26
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Eddy RJ, Han J, Sauterer RA, Condeelis JS. A major agonist-regulated capping activity in Dictyostelium is due to the capping protein, cap32/34. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1314:247-59. [PMID: 8982279 DOI: 10.1016/s0167-4889(96)00108-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Stimulation of starved Dictyostelium amoebae with the chemoattractant cAMP produces a rapid increase in actin nucleation activity at 5 seconds which is cotemporal with an increase in actin assembly and a decrease in Ca(2+)-insensitive capping activity [1]. Further characterization of this capping activity, called aginactin, led to the isolation of an Hsc70 [2]. Here, we demonstrate that purified aginactin contains both Hsc70 and the heterodimeric barbed-end capping protein, cap32/34. Immunoprecipitation of cap32/34 from purified aginactin removes all capping activity while immunoprecipitation of Hsc70 does not, indicating that the capping activity of aginactin is an intrinsic property of cap32/34. Gel filtration and immunoprecipitation assays fail to demonstrate the existence of a stable, high affinity complex between Hsc70 and cap32/34 in either lysate supernatants or aginactin pools but indicate the presence of a transient, ATP-sensitive interaction in cell lysates. Reconstitution experiments with purified Hsc70 and cap32/34 demonstrate that Hsc70 neither stimulates nor inhibits the capping activity of native cap32/34. Furthermore, we measured a Kd of approx. 0.8 nM for the binding of cap32/34 to barbed ends of actin filaments in the absence or presence of Hsc70, in agreement with Kd values measured for purified capping protein from other sources. We conclude, therefore, that cap32/34 is responsible for the capping activity called aginactin and that Hsc70 is not a regulatory cofactor for cap32/34 in Dictyostelium but may function as a chaperone during assembly of the cap32/34 heterodimer.
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Affiliation(s)
- R J Eddy
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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27
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Association of HSP90 with the heme-regulated eukaryotic initiation factor 2α kinase—A collaboration for regulating protein synthesis. J Biosci 1996. [DOI: 10.1007/bf02703108] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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28
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Maun NA, Speicher DW, DiNubile MJ, Southwick FS. Purification and properties of a Ca(2+)-independent barbed-end actin filament capping protein, CapZ, from human polymorphonuclear leukocytes. Biochemistry 1996; 35:3518-24. [PMID: 8639502 DOI: 10.1021/bi952470p] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In human polymorphonuclear leukocytes (PMN), changes in the actin architecture are critical for the shape changes required for chemotaxis and phagocytosis. Barbed-end capping proteins are likely to regulate actin assembly in PMN. The previously identified barbed-end blocking proteins in PMN, gelsolin and CapG, require Ca(2+) to initiate capping of actin filaments. Because chemoattractants can stimulate PMN actin assembly by a calcium-independent signal transduction pathway, we sought to purify a calcium-independent barbed-end capping activity from PMN cytoplasmic extracts. A Ca(2+) -insensitive actin polymerization inhibitory activity was partially purified from human PMN [Southwick & Stossel (1981) J. Biol. Chem 256, 3030]. Using five column chromatography steps, we purified the protein to homogeneity as assessed by silver staining. Purification was associated with an increase in specific activity of greater than 40 X. Western blot analysis identified the protein as the nonmuscle isoform of the heterodimeric capping protein capZ. Human PMN capZ has an apparent disassociation constant of 3 nM for capping in the presence or absence of micromolar Ca(2+), as assessed by both pyrenylactin elongation and depolymerization assays. Similar to the activity reported for the actin polymerization inhibitor, activity of PMN capZ was inhibited by increasing the KC1 concentration from 0.1 M to 0.6 M. The capping function was also inhibited by phosphatidylinositol 4,5-bisphosphate (PIP(2)) micelles, with half-maximal inhibition occurring at 5.5 micrograms mL(-1). PMN capZ did not nucleate actin assembly, sequester actin monomers, or sever actin filaments. Quantitative Western blot analysis revealed that capZ levels corresponded to 0.7-1.0% of the total human PMN cytoplasmic protein. Given its abundance and high affinity for barbed filament ends, capZ is likely to play an important role in the calcium-independent regulation of actin filament assembly associated with PMN chemotaxis.
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Affiliation(s)
- N A Maun
- University of Florida College of Medicine, Division of Infectious Diseases, Gainesville, 32610, USA
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29
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Buxbaum E, Woodman PG. The speed of partial reactions of the uncoating ATPase Hsc70 depends on the source of coated vesicles. J Cell Sci 1996; 109 ( Pt 3):705-11. [PMID: 8907715 DOI: 10.1242/jcs.109.3.705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hsc70 was previously isolated by its ability to catalyse the uncoating of clathrin-coated vesicles from bovine brain. We have recently shown that Hsc70 is more active towards coated vesicles from brain than those from other tissues. In order to gain information on the mechanistic reason for this difference we have examined the ability of brain and placental coated vesicles to stimulate partial reactions during a single round of ATP turnover. The Hsc70-ATP complex is turned over to Hsc70-ADP center dot Pi, from which phosphate is slowly released. The resulting Hsc70-ADP complex exchanges ATP for ADP. Dissociation of ATP or ADP from Hsc70 does not seem to occur under physiological conditions. The hydrolysis of ATP is accelerated by the presence of clathrin-coated vesicles, with vesicles from brain being about twice as effective as vesicles from placenta. Additionally, it appears that brain, but not placental, coated vesicles can also stimulate the exchange of ADP for ATP.
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Affiliation(s)
- E Buxbaum
- Division of Biochemistry, School of Biological Sciences, University of Manchester, UK.
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30
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Nachmias VT, Golla R, Casella JF, Barron-Casella E. Cap Z, a calcium insensitive capping protein in resting and activated platelets. FEBS Lett 1996; 378:258-62. [PMID: 8557113 DOI: 10.1016/0014-5793(95)01474-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Capping of the barbed-ends of actin filaments is an important mechanism for control of the cytoskeleton. In platelets, a valuable model system, it has been thought that gelsolin was the major capping protein. We now report that platelets contain approximately 2 microM Cap Z, a calcium insensitive heterodimeric capping protein; two major and additional minor isoforms of both alpha and beta subunits are present. In lysates from resting platelets 75-80% of the Cap Z sediments with the high speed pellet, but if the platelets are activated with thrombin for 10 s, about 15% of the Cap Z leaves the pellet fraction and is found in the high speed supernatant where it is not bound to actin. This translocation of Cap Z to the supernatant is also observed when resting platelets are lysed into buffer containing 50-100 microM GTP gamma S and 10 mM EGTA. Our results suggest that release of Cap Z from some actin filaments could generate free filament barbed-ends. An increase in free barbed-ends has been reported in platelet lysates prepared shortly after thrombin activation.
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Affiliation(s)
- V T Nachmias
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia 19104-6058, USA
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31
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Abstract
New avenues of cytoskeleton research in Dictyostelium discoideum have opened up with the cloning of the alpha- and beta-tubulin genes and the characterization of kinesins and cytoplasmic dynein. Much research, however, continues to focus on the actin cytoskeleton and its dynamics during chemotaxis, morphogenesis, and other motile processes. New actin-associated proteins are being identified and characterized by biochemical means and through isolation of mutants lacking individual components. This work is shedding light on the roles of specific actin assemblies in various biological processes.
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Affiliation(s)
- A A Noegel
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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Röhrig U, Gerisch G, Morozova L, Schleicher M, Wegner A. Coactosin interferes with the capping of actin filaments. FEBS Lett 1995; 374:284-6. [PMID: 7589554 DOI: 10.1016/0014-5793(95)01130-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Coactosin, a 16 kDa protein associated with the actin cytoskeleton from Dictyostelium discoideum, was purified by an improved method, in which other components of the cytoskeleton were removed. The highly purified coactosin had no effect on the time course of actin polymerization, but when added to actin in presence of capping proteins, coactosin counteracted the capping activity of these proteins. The capping proteins cap32/34 and severin domain 1 retarded actin polymerization, on addition of coactosin to samples containing one of these capping proteins the time course of actin polymerization became close to controls without capping proteins.
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Affiliation(s)
- U Röhrig
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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33
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Kabakov AE, Molotkov AO, Budagova KR, Mosin AF, Gabai VL. Adaptation of Ehrlich ascites carcinoma cells to energy deprivation in vivo can be associated with heat shock protein accumulation. J Cell Physiol 1995; 165:1-6. [PMID: 7559791 DOI: 10.1002/jcp.1041650102] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Tumor adaptation to chronic energy starvation in vivo was studied on Ehrlich ascites carcinoma (EAC) cells. EAC cells were isolated from mice and incubated in a glucose-free medium containing blocators of mitochondrial ATP generation (rotenone, 2,4-dinitrophenol, or oligomycin). ATP level in the treated cells decreased to 3-4% of the initial during 30 min of the incubation. The aggregation of cytoskeletal proteins, blebbing, and necrotic death within 2-3 h were observed in ATP-depleted EAC which were isolated and treated in the exponential phase of growth (5 days after inoculation), whereas stationary EAC (8 days after inoculation) were considerably more resistant to ATP depletion, and actin aggregation as well as bleb formation were suppressed in these cells despite the ATP loss. In contrast to the exponentially growing cells, thermotolerance and unexpected expression of inducible HSP68 and HSP27 as well as an elevated level of HSP90 were found in stationary EAC. Since the stationary cells had decreased content of ATP, ATP/ADP ratio, and energy charge, we suggest that this energy dysbalance may be conducive to HSP induction within the ascites tumor in vivo, and, at the same time, EAC cells with elevated content of HSPs acquire resistance to chronic energy starvation occurring in late stages of the tumor growth.
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Affiliation(s)
- A E Kabakov
- Medical Radiology Research Center of Russian Academy of Medical Sciences, Obninsk
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34
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Buxbaum E, Woodman PG. Selective action of uncoating ATPase towards clathrin-coated vesicles from brain. J Cell Sci 1995; 108 ( Pt 3):1295-306. [PMID: 7622612 DOI: 10.1242/jcs.108.3.1295] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Clathrin-coated vesicles from brain are primarily involved in synaptic vesicle recycling and are substrates for the constitutively expressed heat shock cognate hsc70 protein (uncoating ATPase). To investigate the regulation of clathrin coat turnover in other tissues the activity of hsc70 towards coated vesicles from other sources was examined. Concentrations of hsc70 which caused near-complete removal of clathrin from brain coated vesicles effected only partial uncoating of vesicles prepared from other tissues. The selective action of hsc70 could not be accounted for by tissue or species specificities of hsc70, but rather reflected differences in coat structure. Selective action was associated with two differences in the hsc70-dependent ATPase cycle. Firstly, uncoating of brain, but not placental vesicles, could occur under circumstances where ATP hydrolysis was prevented. Secondly, only brain coated vesicles could support multiple rounds of hsc70-dependent ATP hydrolysis. Implications of these findings for the mechanism of hsc70-dependent vesicle uncoating in non-neuronal cells and the organisation of the endocytic pathway in the axon are discussed.
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Affiliation(s)
- E Buxbaum
- Division of Biochemistry, School of Biological Sciences, University of Manchester, UK
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Liao J, Lowthert LA, Ghori N, Omary MB. The 70-kDa heat shock proteins associate with glandular intermediate filaments in an ATP-dependent manner. J Biol Chem 1995; 270:915-22. [PMID: 7529764 DOI: 10.1074/jbc.270.2.915] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Keratin polypeptides 8 and 18 (K8/18) are intermediate filament proteins expressed preferentially in glandular epithelia. We describe the identification, by co-immunoprecipitation from normal human colonic tissues and cultured cell lines, of the 70-kDa heat shock protein (hsp) and its related heat shock cognate protein as K8/18-associated proteins (hsp/c). The association is significant but sub-stoichiometric and occurs preferentially with the soluble rather than the cytoskeletal K8/18 fractions. Heat stress increases the level of soluble K8/18 in association with an increase in hsp70 levels and an increase in the stoichiometry of K8/18-hsp70 association. Identity of the associated proteins was confirmed by microsequencing of a tryptic digest of the purified associated protein and by using anti-hsp/c70-specific antibodies. The K8/18-hsp/c70 complex can be dissociated in a Mg-ATP-dependent manner that requires ATP hydrolysis. Binding of hsp to K8/18 can be reconstituted using purified bovine hsp70 and human K8/18 immunoprecipitates that have been depleted of bound hsp/c70 and increases slightly in the presence of ATP. The reconstituted K8/18-hsp70 complex can be again released in the presence of Mg-ATP. In addition, hsp70 binds to K8/18 without having a significant effect on in vitro filament assembly when added during or after assembly. Using an overlay assay, hsp70 binds exclusively to K8 in the presence of ATP. Our results show direct association of the hsp/c70 proteins with K8/18. This interaction may serve, at least in part, to regulate the function of these two abundant protein groups.
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Affiliation(s)
- J Liao
- Palo Alto Veterans Affairs Medical Center, California 94304
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36
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Affiliation(s)
- O B Ptitsyn
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia
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37
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Kabakov AE, Gabai VL. Heat-shock proteins maintain the viability of ATP-deprived cells: what is the mechanism? Trends Cell Biol 1994; 4:193-6. [PMID: 14731676 DOI: 10.1016/0962-8924(94)90135-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
ATP depletion causes necrosis in mammalian cells. However, a previous heat shock can protect cells from the effects of energy deprivation, probably as a result of the synthesis and accumulation of heat-shock proteins (hsps). We propose that hsps protect ATP-depleted cells from rapid necrotic death by inhibiting the aggregation of cytoskeletal proteins that occurs when ATP synthesis is blocked.
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Affiliation(s)
- A E Kabakov
- Department of Radiation Biochemistry, Medical Radiology Research Center, 4 Korolev St, Obninsk 249020, Russia
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Jungbluth A, von Arnim V, Biegelmann E, Humbel B, Schweiger A, Gerisch G. Strong increase in the tyrosine phosphorylation of actin upon inhibition of oxidative phosphorylation: correlation with reversible rearrangements in the actin skeleton of Dictyostelium cells. J Cell Sci 1994; 107 ( Pt 1):117-25. [PMID: 7513710 DOI: 10.1242/jcs.107.1.117] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When oxidative phosphorylation is inhibited in cells of Dictyostelium discoideum, the phosphorylation of tyrosine residues on actin is strongly increased. This increase is fully reversible. Under the same conditions the amoeboid cells undergo a series of shape changes. Within three minutes the pseudopods are withdrawn and replaced by cell surface blebs. Subsequently, the cells are rounding up to become immobile. In parallel with the changes in cell shape, the distribution of actin filaments is grossly altered within the cells. The cortical network of actin filaments of normal cells is broken down, and the F-actin forms large, irregular clusters deep within the cytoplasm. In these clusters the actin is associated with myosin II and with the heterodimeric F-actin capping protein cap32/34. After restoration of oxidative phosphorylation the actin returns within less than four minutes to its normal cortical position. A causal relationship between tyrosine phosphorylation and changes in the distribution of actin remains to be established. The rearrangements in the actin system that result from the inhibition of oxidative phosphorylation indicate that the organisation of this system and its maintenance in a functional state depend on the continuous supply of energy by ATP.
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Affiliation(s)
- A Jungbluth
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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