1
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Wang WC, Zhang XF, Tang EJ, Li AJ, Chen L, Wang JQ, Ma JY, Zhang XF, Sun B. Thymosin β4, a potential marker of malignancy and prognosis in hepatocellular carcinoma. Scand J Gastroenterol 2023; 58:380-391. [PMID: 36269095 DOI: 10.1080/00365521.2022.2136012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND The lack of effective early diagnostic markers is an obstacle in clinical diagnosis and treatment of hepatocellular carcinoma (HCC). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is an increasing popular approach for identification of clinically relevant parameters including biomarkers. PATIENTS AND METHODS 540 subjects, including 274 HCC, 119 liver cirrhosis, 89 hepatitis, and 58 healthy volunteers were enrolled. MALDI-TOF MS was used to select potential novel biomarkers from serum of HCC patients. Its clinical application was evaluated by experiments and clinical data analysis. RESULTS We identified Thymosin β4 (Tβ4) in serum by MALDI-TOF MS. The expression of Tβ4 was detected up-regulating in HCC cells and tissues which enhanced motility of HCC cells. More important, the level of serum Tβ4 was significantly elevated in HCC patients. The AUROC showed the optimum diagnostic cut-off was 1063.6 ng/mL, ROC and 95% CI of Tβ4 (0.908; 0.880-0.935) were larger than that of serum AFP (0.712; 0.662-0.762; p < 0.001). The sensitivity (91.3% vs 83.1%) and specificity (81.2% vs 20.3%) of serum Tβ4 were higher than alpha-fetoprotein (AFP). In AFP-negative HCC, the sensitivity could reach to 80.5%. ROC analysis showed serum Tβ4 had a better performance compared with AFP in distinguishing early-stage and small HCC. Tβ4 is correlated with TNM stage (p = 0.016) and vascular invasion (p = 0.005). Survival analysis indicated the survival time of Tβ4 positive patients was shorter (p < 0.001). Cox analysis suggested Tβ4 could be an independent factor for HCC prognosis. CONCLUSION Tβ4 may serve as a novel biomarker for HCC diagnosis and prognosis.
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Affiliation(s)
- Wen-Chao Wang
- Department of General Surgery, Yangpu Hospital, School of Medicine, Tongji University, Shanghai, P. R. China
| | - Xiao-Feng Zhang
- School of Medicine, Shanghai University, Shanghai, P. R. China
| | - Er-Jiang Tang
- Center for Clinical Research and Translational Medicine, Yangpu Hospital, School of Medicine, Tongji University, Shanghai, P. R. China
| | - A-Jian Li
- Department of General Surgery, Yangpu Hospital, School of Medicine, Tongji University, Shanghai, P. R. China
| | - Lei Chen
- Center for Clinical Research and Translational Medicine, Yangpu Hospital, School of Medicine, Tongji University, Shanghai, P. R. China
| | - Jia-Qi Wang
- Department of General Surgery, Yangpu Hospital, School of Medicine, Tongji University, Shanghai, P. R. China
| | - Jun-Yong Ma
- Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Navy Military Medical University, Shanghai, P. R. China
| | - Xiao-Feng Zhang
- Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Navy Military Medical University, Shanghai, P. R. China
| | - Bin Sun
- Center for Clinical Research and Translational Medicine, Yangpu Hospital, School of Medicine, Tongji University, Shanghai, P. R. China
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2
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Hardin WR, Alas GCM, Taparia N, Thomas EB, Steele-Ogus MC, Hvorecny KL, Halpern AR, Tůmová P, Kollman JM, Vaughan JC, Sniadecki NJ, Paredez AR. The Giardia ventrolateral flange is a lamellar membrane protrusion that supports attachment. PLoS Pathog 2022; 18:e1010496. [PMID: 35482847 PMCID: PMC9089883 DOI: 10.1371/journal.ppat.1010496] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/10/2022] [Accepted: 04/04/2022] [Indexed: 12/01/2022] Open
Abstract
Attachment to the intestinal epithelium is critical to the lifestyle of the ubiquitous parasite Giardia lamblia. The ventrolateral flange is a sheet-like membrane protrusion at the interface between parasites and attached surfaces. This structure has been implicated in attachment, but its role has been poorly defined. Here, we identified a novel actin associated protein with putative WH2-like actin binding domains we named Flangin. Flangin complexes with Giardia actin (GlActin) and is enriched in the ventrolateral flange making it a valuable marker for studying the flanges' role in Giardia biology. Live imaging revealed that the flange grows to around 1 μm in width after cytokinesis, then remains uniform in size during interphase, grows in mitosis, and is resorbed during cytokinesis. A flangin truncation mutant stabilizes the flange and blocks cytokinesis, indicating that flange disassembly is necessary for rapid myosin-independent cytokinesis in Giardia. Rho family GTPases are important regulators of membrane protrusions and GlRac, the sole Rho family GTPase in Giardia, was localized to the flange. Knockdown of Flangin, GlActin, and GlRac result in flange formation defects. This indicates a conserved role for GlRac and GlActin in forming membrane protrusions, despite the absence of canonical actin binding proteins that link Rho GTPase signaling to lamellipodia formation. Flangin-depleted parasites had reduced surface contact and when challenged with fluid shear force in flow chambers they had a reduced ability to remain attached, confirming a role for the flange in attachment. This secondary attachment mechanism complements the microtubule based adhesive ventral disc, a feature that may be particularly important during mitosis when the parental ventral disc disassembles in preparation for cytokinesis. This work supports the emerging view that Giardia's unconventional actin cytoskeleton has an important role in supporting parasite attachment.
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Affiliation(s)
- William R. Hardin
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Germain C. M. Alas
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Nikita Taparia
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
| | - Elizabeth B. Thomas
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Melissa C. Steele-Ogus
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Kelli L. Hvorecny
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Aaron R. Halpern
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
| | - Pavla Tůmová
- Institute of Immunology and Microbiology, 1 Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Justin M. Kollman
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Joshua C. Vaughan
- Department of Chemistry, University of Washington, Seattle, Washington, United States of America
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Nathan J. Sniadecki
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, United States of America
- Bioengineering, University of Washington, Seattle, Washington, United States of America
- Lab Medicine & Pathology, University of Washington, Seattle, Washington, United States of America
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington, United States of America
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Alexander R. Paredez
- Department of Biology, University of Washington, Seattle, Washington, United States of America
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3
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Gübeli RJ, Bertoldo D, Shimada K, Gerhold CB, Hurst V, Takahashi Y, Harada K, Mothukuri GK, Wilbs J, Harata M, Gasser SM, Heinis C. In Vitro-Evolved Peptides Bind Monomeric Actin and Mimic Actin-Binding Protein Thymosin-β4. ACS Chem Biol 2021; 16:820-828. [PMID: 33843189 DOI: 10.1021/acschembio.0c00825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Actin is the most abundant protein in eukaryotic cells and is key to many cellular functions. The filamentous form of actin (F-actin) can be studied with help of natural products that specifically recognize it, as for example fluorophore-labeled probes of the bicyclic peptide phalloidin, but no synthetic probes exist for the monomeric form of actin (G-actin). Herein, we have panned a phage display library consisting of more than 10 billion bicyclic peptides against G-actin and isolated binders with low nanomolar affinity and greater than 1000-fold selectivity over F-actin. Sequence analysis revealed a strong similarity to a region of thymosin-β4, a protein that weakly binds G-actin, and competition binding experiments confirmed a common binding region at the cleft between actin subdomains 1 and 3. Together with F-actin-specific peptides that we also isolated, we evaluated the G-actin peptides as probes in pull-down, imaging, and competition binding experiments. While the F-actin peptides were applied successfully for capturing actin in cell lysates and for imaging, the G-actin peptides did not bind in the cellular context, most likely due to competition with thymosin-β4 or related endogenous proteins for the same binding site.
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Affiliation(s)
- Raphael J. Gübeli
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Davide Bertoldo
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Kenji Shimada
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Christian B. Gerhold
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Verena Hurst
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- Faculty of Natural Sciences, University of Basel, 4056 Basel, Switzerland
| | - Yuichiro Takahashi
- Laboratory of Molecular Biology, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoba-ku, Sendai 981-8555, Japan
| | - Kai Harada
- Laboratory of Molecular Biology, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoba-ku, Sendai 981-8555, Japan
| | - Ganesh K. Mothukuri
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Jonas Wilbs
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Masahiko Harata
- Laboratory of Molecular Biology, Tohoku University, Tsutsumidori-Amamiyamachi 1-1, Aoba-ku, Sendai 981-8555, Japan
| | - Susan M. Gasser
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- Faculty of Natural Sciences, University of Basel, 4056 Basel, Switzerland
| | - Christian Heinis
- Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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4
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Dutta P, Jijumon AS, Mazumder M, Dileep D, Mukhopadhyay AK, Gourinath S, Maiti S. Presence of actin binding motif in VgrG-1 toxin of Vibrio cholerae reveals the molecular mechanism of actin cross-linking. Int J Biol Macromol 2019; 133:775-785. [PMID: 31002899 DOI: 10.1016/j.ijbiomac.2019.04.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/04/2019] [Accepted: 04/04/2019] [Indexed: 11/27/2022]
Abstract
Type VI secretion systems (T6SS) plays a crucial role in Vibrio cholerae mediated pathogenicity. Tip of T6SS is homologous to gp27/gp5 complex or tail spike of T4 bacteriophage. VgrG-1 of V. cholerae T6SS is unusual among other VgrG because its effector domain is trans-located into the cytosol of eukaryotic cells with an additional actin cross-linking domain (ACD) at its C terminal end. ACD of VgrG-1 (VgrG-1-ACD) causes T6SS dependent host cell cytotoxicity through actin cytoskeleton disruption to prevent bacterial engulfment by macrophages. ACD mediated actin cross-linking promotes survival of the bacteria in the small intestine of humans, along with other virulence factors; establishes successful infection with the onset of diarrhoea in humans. Our studies demonstrated VgrG-1-ACD can bind to actin besides actin cross-linking activity. Computational analysis of ACD revealed the presence of actin binding motif (ABM). Mutations in ABM lead to loss of actin binding in vitro. VgrG-1-ACD having the mutated ABM cannot cross-link actin efficiently in vitro and manifests less actin cytoskeleton disruption when transfected in HeLa cells.
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Affiliation(s)
- Priyanka Dutta
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India
| | - A S Jijumon
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India
| | | | - Drisya Dileep
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India
| | | | | | - Sankar Maiti
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Nadia, West Bengal, India.
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5
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Isogai T, Danuser G. Discovery of functional interactions among actin regulators by analysis of image fluctuations in an unperturbed motile cell system. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0110. [PMID: 29632262 DOI: 10.1098/rstb.2017.0110] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2017] [Indexed: 01/06/2023] Open
Abstract
Cell migration is driven by propulsive forces derived from polymerizing actin that pushes and extends the plasma membrane. The underlying actin network is constantly undergoing adaptation to new mechano-chemical environments and intracellular conditions. As such, mechanisms that regulate actin dynamics inherently contain multiple feedback loops and redundant pathways. Given the highly adaptable nature of such a system, studies that use only perturbation experiments (e.g. knockdowns, overexpression, pharmacological activation/inhibition, etc.) are challenged by the nonlinearity and redundancy of the pathway. In these pathway configurations, perturbation experiments at best describe the function(s) of a molecular component in an adapting (e.g. acutely drug-treated) or fully adapted (e.g. permanent gene silenced) cell system, where the targeted component now resides in a non-native equilibrium. Here, we propose how quantitative live-cell imaging and analysis of constitutive fluctuations of molecular activities can overcome these limitations. We highlight emerging actin filament barbed-end biology as a prime example of a complex, nonlinear molecular process that requires a fluctuation analytic approach, especially in an unperturbed cellular system, to decipher functional interactions of barbed-end regulators, actin polymerization and membrane protrusion.This article is part of the theme issue 'Self-organization in cell biology'.
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Affiliation(s)
- Tadamoto Isogai
- Department of Cell Biology, Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Gaudenz Danuser
- Department of Cell Biology, Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX 75390, USA
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6
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Feng XW, Huo LJ, Yang MC, Wang JX, Shi XZ. Thymosins participate in antibacterial immunity of kuruma shrimp, Marsupenaeus japonicus. FISH & SHELLFISH IMMUNOLOGY 2019; 84:244-251. [PMID: 30292805 DOI: 10.1016/j.fsi.2018.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/22/2018] [Accepted: 10/03/2018] [Indexed: 06/08/2023]
Abstract
Thymosins β are actin-binding proteins that play a variety of different functions in inflammatory responses, wound healing, cell migration, angiogenesis, and stem cell recruitment and differentiation. In crayfish, thymosins participate in antiviral immunology. However, the roles of thymosin during bacterial infection in shrimp remain unclear. In the present study, four thymosins were identified from kuruma shrimp, Marsupenaeus japonicus, and named as Mjthymosin2, Mjthymosin3, Mjthymosin4, and Mjthymosin5 according the number of their thymosin beta actin-binding motifs. Mjthymosin3 was selected for further study because its expression level was the highest in hemocytes. Expression analysis showed that Mjthymosin3 was upregulated in hemocytes after challenged by Vibrio anguillarum or Staphylococcus aureus. The recombinant Mjthymosin3 protein could inhibit the growth of certain bacteria in an in vitro antibacterial test. Mjthymosins could facilitate external bacterial clearance in shrimp, and were beneficial to shrimp survival post V. anguillarum or S. aureus infection. The results suggested that Mjthymosins played important roles in the antibacterial immune response of kuruma shrimp.
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Affiliation(s)
- Xiao-Wu Feng
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China
| | - Li-Jie Huo
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China
| | - Ming-Chong Yang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China
| | - Jin-Xing Wang
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China
| | - Xiu-Zhen Shi
- Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China.
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7
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Popinako A, Antonov M, Dibrova D, Chemeris A, Sokolova OS. Analysis of the interactions between GMF and Arp2/3 complex in two binding sites by molecular dynamics simulation. Biochem Biophys Res Commun 2018; 496:529-535. [PMID: 29339159 DOI: 10.1016/j.bbrc.2018.01.080] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 01/11/2018] [Indexed: 12/17/2022]
Abstract
The Arp2/3 complex plays a key role in nucleating actin filaments branching. The glia maturation factor (GMF) competes with activators for interacting with the Arp2/3 complex and initiates the debranching of actin filaments. In this study, we performed a comparative analysis of interactions between GMF and the Arp2/3 complex and identified new amino acid residues involved in GMF binding to the Arp2/3 complex at two separate sites, revealed by X-ray and single particle EM techniques. Using molecular dynamics simulations we demonstrated the quantitative and qualitative changes in hydrogen bonds upon binding with GMF. We identified the specific amino acid residues in GMF and Arp2/3 complex that stabilize the interactions and estimated the mean force profile for the GMF using umbrella sampling. Phylogenetic and structural analyses of the recently defined GMF binding site on the Arp3 subunit indicate a new mechanism for Arp2/3 complex inactivation that involves interactions between the Arp2/3 complex and GMF at two binding sites.
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Affiliation(s)
- A Popinako
- A.N. Bach Institute of Biochemistry, Research Center of Biotechnology of RAS, 33 Leninsky Ave, bld. 2, Moscow, 119071, Russia
| | - M Antonov
- M.K. Ammosov North-Eastern Federal University, 58 Belinskiy str, suite 312, Yakutsk, 677980, Republic of Sakha (Yakutia), Russia
| | - D Dibrova
- Lomonosov Moscow State University, Faculty of Biology, 1 Leninskie gory, bld 12, Moscow, 119234, Russia
| | - A Chemeris
- Lomonosov Moscow State University, Faculty of Biology, 1 Leninskie gory, bld 12, Moscow, 119234, Russia
| | - O S Sokolova
- Lomonosov Moscow State University, Faculty of Biology, 1 Leninskie gory, bld 12, Moscow, 119234, Russia.
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8
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Zhang Y, Yoshida A, Sakai N, Uekusa Y, Kumeta M, Yoshimura SH. In vivo dynamics of the cortical actin network revealed by fast-scanning atomic force microscopy. Microscopy (Oxf) 2017; 66:272-282. [DOI: 10.1093/jmicro/dfx015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/29/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Yanshu Zhang
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Aiko Yoshida
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | | - Masahiro Kumeta
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shige H. Yoshimura
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
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9
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Cenik BK, Garg A, McAnally JR, Shelton JM, Richardson JA, Bassel-Duby R, Olson EN, Liu N. Severe myopathy in mice lacking the MEF2/SRF-dependent gene leiomodin-3. J Clin Invest 2015; 125:1569-78. [PMID: 25774500 DOI: 10.1172/jci80115] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 01/29/2015] [Indexed: 01/18/2023] Open
Abstract
Maintenance of skeletal muscle structure and function requires a precise stoichiometry of sarcomeric proteins for proper assembly of the contractile apparatus. Absence of components of the sarcomeric thin filaments causes nemaline myopathy, a lethal congenital muscle disorder associated with aberrant myofiber structure and contractility. Previously, we reported that deficiency of the kelch-like family member 40 (KLHL40) in mice results in nemaline myopathy and destabilization of leiomodin-3 (LMOD3). LMOD3 belongs to a family of tropomodulin-related proteins that promote actin nucleation. Here, we show that deficiency of LMOD3 in mice causes nemaline myopathy. In skeletal muscle, transcription of Lmod3 was controlled by the transcription factors SRF and MEF2. Myocardin-related transcription factors (MRTFs), which function as SRF coactivators, serve as sensors of actin polymerization and are sequestered in the cytoplasm by actin monomers. Conversely, conditions that favor actin polymerization de-repress MRTFs and activate SRF-dependent genes. We demonstrated that the actin nucleator LMOD3, together with its stabilizing partner KLHL40, enhances MRTF-SRF activity. In turn, SRF cooperated with MEF2 to sustain the expression of LMOD3 and other components of the contractile apparatus, thereby establishing a regulatory circuit to maintain skeletal muscle function. These findings provide insight into the molecular basis of the sarcomere assembly and muscle dysfunction associated with nemaline myopathy.
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10
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Siton O, Bernheim-Groswasser A. Reconstitution of actin-based motility by vasodilator-stimulated phosphoprotein (VASP) depends on the recruitment of F-actin seeds from the solution produced by cofilin. J Biol Chem 2014; 289:31274-86. [PMID: 25246528 DOI: 10.1074/jbc.m114.586958] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Vasodilator-stimulated phosphoprotein (VASP) is active in many filopodium-based and cytoskeleton reorganization processes. It is not fully understood how VASP directly functions in actin-based motility and how regulatory proteins affect its function. Here, we combine bead motility assay and single filament experiments. In the presence of a bundling component, actin bundles that grow from the surface of WT-VASP-coated beads induced movement of the beads. VASP promotes actin-based movement alone, in the absence of other actin nucleators. We propose that at physiological salt conditions VASP nucleation activity is too weak to promote motility and bundle formation. Rather, VASP recruits F-actin seeds from the solution and promotes their elongation. Cofilin has a crucial role in the nucleation of these F-actin seeds, notably under conditions of unfavorable spontaneous actin nucleation. We explored the role of multiple VASP variants. We found that the VASP-F-actin binding domain is required for the recruitment of F-actin seeds from the solution. We also found that the interaction of profilin-actin complexes with the VASP-proline-rich domain and the binding of the VASP-F-actin binding domain to the side of growing filaments is critical for transforming actin polymerization into motion. At the single filament level, profilin mediates both filament elongation rate and VASP anti-capping activity. Binding of profilin-actin complexes increases the polymerization efficiency by VASP but decreases its efficiency as an anti-capper; binding of free profilin creates the opposite effect. Finally, we found that an additional component such as methylcellulose or fascin is required for actin bundle formation and motility mediated by VASP.
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Affiliation(s)
- Orit Siton
- From the Department of Chemical Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Anne Bernheim-Groswasser
- From the Department of Chemical Engineering and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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11
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Rasson AS, Bois JS, Pham DSL, Yoo H, Quinlan ME. Filament assembly by Spire: key residues and concerted actin binding. J Mol Biol 2014; 427:824-839. [PMID: 25234086 DOI: 10.1016/j.jmb.2014.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 07/28/2014] [Accepted: 09/04/2014] [Indexed: 01/09/2023]
Abstract
The most recently identified class of actin nucleators, WASp homology domain 2 (WH2) nucleators, use tandem repeats of monomeric actin-binding WH2 domains to facilitate actin nucleation. WH2 domains are involved in a wide variety of actin regulatory activities. Structurally, they are expected to clash with interprotomer contacts within the actin filament. Thus, the discovery of their role in nucleation was surprising. Here we use Drosophila Spire (Spir) as a model system to investigate both how tandem WH2 domains can nucleate actin and what differentiates nucleating WH2-containing proteins from their non-nucleating counterparts. We found that the third WH2 domain in Spir (Spir-C or SC) plays a unique role. In the context of a short nucleation construct (containing only two WH2 domains), placement of SC in the N-terminal position was required for the most potent nucleation. We found that the native organization of the WH2 domains with respect to each other is necessary for binding to actin with positive cooperativity. We identified two residues within SC that are critical for its activity. Using this information, we were able to convert a weak synthetic nucleator into one with activity equal to a native Spir construct. Lastly, we found evidence that SC binds actin filaments, in addition to monomers.
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Affiliation(s)
- Amy S Rasson
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive, Los Angeles, CA 90095, USA
| | - Justin S Bois
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive, Los Angeles, CA 90095, USA
| | - Duy Stephen L Pham
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive, Los Angeles, CA 90095, USA
| | - Haneul Yoo
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive, Los Angeles, CA 90095, USA
| | - Margot E Quinlan
- Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles E. Young Drive, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California Los Angeles, Paul D. Boyer Hall, 611 Charles E. Young Drive East, Box 951570, Los Angeles, CA 90095-1570, USA.
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12
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Molecular characterization, tissue distribution, subcellular localization and actin-sequestering function of a thymosin protein from silkworm. PLoS One 2012; 7:e31040. [PMID: 22383992 PMCID: PMC3284464 DOI: 10.1371/journal.pone.0031040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Accepted: 12/30/2011] [Indexed: 02/07/2023] Open
Abstract
We identified a novel gene encoding a Bombyx mori thymosin (BmTHY) protein from a cDNA library of silkworm pupae, which has an open reading frame (ORF) of 399 bp encoding 132 amino acids. It was found by bioinformatics that BmTHY gene consisted of three exons and two introns and BmTHY was highly homologous to thymosin betas (Tβ). BmTHY has a conserved motif LKHTET with only one amino acid difference from LKKTET, which is involved in Tβ binding to actin. A His-tagged BmTHY fusion protein (rBmTHY) with a molecular weight of approximately 18.4 kDa was expressed and purified to homogeneity. The purified fusion protein was used to produce anti-rBmTHY polyclonal antibodies in a New Zealand rabbit. Subcellular localization revealed that BmTHY can be found in both Bm5 cell (a silkworm ovary cell line) nucleus and cytoplasm but is primarily located in the nucleus. Western blotting and real-time RT-PCR showed that during silkworm developmental stages, BmTHY expression levels are highest in moth, followed by instar larvae, and are lowest in pupa and egg. BmTHY mRNA was universally distributed in most of fifth-instar larvae tissues (except testis). However, BmTHY was expressed in the head, ovary and epidermis during the larvae stage. BmTHY formed complexes with actin monomer, inhibited actin polymerization and cross-linked to actin. All the results indicated BmTHY might be an actin-sequestering protein and participate in silkworm development.
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How a single residue in individual β-thymosin/WH2 domains controls their functions in actin assembly. EMBO J 2011; 31:1000-13. [PMID: 22193718 DOI: 10.1038/emboj.2011.461] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 11/18/2011] [Indexed: 12/21/2022] Open
Abstract
β-Thymosin (βT) and WH2 domains are widespread, intrinsically disordered actin-binding peptides that display significant sequence variability and different regulations of actin self-assembly in motile and morphogenetic processes. Here, we reveal the structural mechanisms by which, in their 1:1 stoichiometric complexes with actin, they either inhibit assembly by sequestering actin monomers like Thymosin-β4, or enhance motility by directing polarized filament assembly like Ciboulot βT. We combined mutational, functional or structural analysis by X-ray crystallography, SAXS (small angle X-ray scattering) and NMR on Thymosin-β4, Ciboulot, TetraThymosinβ and the long WH2 domain of WASP-interacting protein. The latter sequesters G-actin with the same molecular mechanisms as Thymosin-β4. Functionally different βT/WH2 domains differ by distinct dynamics of their C-terminal half interactions with G-actin pointed face. These C-terminal interaction dynamics are controlled by the strength of electrostatic interactions with G-actin. At physiological ionic strength, a single salt bridge with actin located next to their central LKKT/V motif induces G-actin sequestration in both isolated long βT and WH2 domains. The results open perspectives for elucidating the functions of βT/WH2 domains in other modular proteins.
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Poukkula M, Kremneva E, Serlachius M, Lappalainen P. Actin-depolymerizing factor homology domain: a conserved fold performing diverse roles in cytoskeletal dynamics. Cytoskeleton (Hoboken) 2011; 68:471-90. [PMID: 21850706 DOI: 10.1002/cm.20530] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 06/29/2011] [Accepted: 08/05/2011] [Indexed: 11/09/2022]
Abstract
Actin filaments form contractile and protrusive structures that play central roles in many processes such as cell migration, morphogenesis, endocytosis, and cytokinesis. During these processes, the dynamics of the actin filaments are precisely regulated by a large array of actin-binding proteins. The actin-depolymerizing factor homology (ADF-H) domain is a structurally conserved protein motif, which promotes cytoskeletal dynamics by interacting with monomeric and/or filamentous actin, and with the Arp2/3 complex. Despite their structural homology, the five classes of ADF-H domain proteins display distinct biochemical activities and cellular roles, only parts of which are currently understood. ADF/cofilin promotes disassembly of aged actin filaments, whereas twinfilin inhibits actin filament assembly via sequestering actin monomers and interacting with filament barbed ends. GMF does not interact with actin, but instead binds Arp2/3 complex and promotes dissociation of Arp2/3-mediated filament branches. Abp1 and drebrin are multidomain proteins that interact with actin filaments and regulate the activities of other proteins during various actin-dependent processes. The exact function of coactosin is currently incompletely understood. In this review article, we discuss the biochemical functions, cellular roles, and regulation of the five groups of ADF-H domain proteins.
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Affiliation(s)
- Minna Poukkula
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Finland
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15
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Molecular basis for the dual function of Eps8 on actin dynamics: bundling and capping. PLoS Biol 2010; 8:e1000387. [PMID: 20532239 PMCID: PMC2879411 DOI: 10.1371/journal.pbio.1000387] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 04/22/2010] [Indexed: 11/20/2022] Open
Abstract
Actin capping and cross-linking proteins regulate the dynamics and architectures of different cellular protrusions. Eps8 is the founding member of a unique family of capping proteins capable of side-binding and bundling actin filaments. However, the structural basis through which Eps8 exerts these functions remains elusive. Here, we combined biochemical, molecular, and genetic approaches with electron microscopy and image analysis to dissect the molecular mechanism responsible for the distinct activities of Eps8. We propose that bundling activity of Eps8 is mainly mediated by a compact four helix bundle, which is contacting three actin subunits along the filament. The capping activity is mainly mediated by a amphipathic helix that binds within the hydrophobic pocket at the barbed ends of actin blocking further addition of actin monomers. Single-point mutagenesis validated these modes of binding, permitting us to dissect Eps8 capping from bundling activity in vitro. We further showed that the capping and bundling activities of Eps8 can be fully dissected in vivo, demonstrating the physiological relevance of the identified Eps8 structural/functional modules. Eps8 controls actin-based motility through its capping activity, while, as a bundler, is essential for proper intestinal morphogenesis of developing Caenorhabditis elegans.
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Chaudhry F, Little K, Talarico L, Quintero-Monzon O, Goode BL. A central role for the WH2 domain of Srv2/CAP in recharging actin monomers to drive actin turnover in vitro and in vivo. Cytoskeleton (Hoboken) 2010; 67:120-33. [PMID: 20169536 PMCID: PMC2857556 DOI: 10.1002/cm.20429] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 12/18/2009] [Indexed: 11/08/2022]
Abstract
Cellular processes propelled by actin polymerization require rapid disassembly of filaments, and then efficient recycling of ADF/cofilin-bound ADP-actin monomers back to an assembly-competent ATP-bound state. How monomer recharging is regulated in vivo is still not well understood, but recent work suggests the involvement of the ubiquitous actin-monomer binding protein Srv2/CAP. To better understand Srv2/CAP mechanism, we explored the contribution of its WH2 domain, the function of which has remained highly elusive. We found that the WH2 domain binds to actin monomers and, unlike most other WH2 domains, exhibits similar binding affinity for ATP-actin and ADP-actin (K(d) approximately 1.5 microM). Mutations in the WH2 domain that impair actin binding disrupt the ability of purified full-length Srv2/CAP to catalyze nucleotide exchange on ADF/cofilin-bound actin monomers and accelerate actin turnover in vitro. The same mutations impair Srv2/CAP function in vivo in regulating actin organization, cell growth, and cell morphogenesis. Thus, normal cell growth and organization depend on the ability of Srv2/CAP to recharge actin monomers, and the WH2 domain plays a central role in this process. Our data also reveal that while most isolated WH2 domains inhibit nucleotide exchange on actin, WH2 domains in the context of intact proteins can help promote nucleotide exchange.
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Affiliation(s)
- Faisal Chaudhry
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts, USA
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17
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Watanabe N. Inside view of cell locomotion through single-molecule: fast F-/G-actin cycle and G-actin regulation of polymer restoration. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2010; 86:62-83. [PMID: 20075609 PMCID: PMC3417570 DOI: 10.2183/pjab.86.62] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 11/09/2009] [Indexed: 05/28/2023]
Abstract
The actin cytoskeleton drives cell locomotion and tissue remodeling. The invention of live-cell fluorescence single-molecule imaging opened a window for direct viewing of the actin remodeling processes in the cell. Since then, a number of unanticipated molecular functions have been revealed. One is the mechanism of F-actin network breakdown. In lamellipodia, one third of newly polymerized F-actin disassembles within 10 seconds. This fast F-actin turnover is facilitated by the filament severing/disrupting activity involving cofilin and AIP1. Astoundingly fast dissociation kinetics of the barbed end interactors including capping protein suggests that F-actin turnover might proceed through repetitive disruption/reassembly of the filament near the barbed end. The picture of actin polymerization is also being revealed. At the leading edge of the cell, Arp2/3 complex is highly activated in a narrow edge region. In contrast, mDia1 and its related Formin homology proteins display a long-distance directional molecular movement using their processive actin capping ability. Recently, these two independently-developed projects converged into a discovery of the spatiotemporal coupling between mDia1-mediated filament nucleation and actin disassembly. Presumably, the local concentration fluctuation of G-actin regulates the actin nucleation efficiency of specific actin nucleators including mDia1. Pharmacological perturbation and quantitative molecular behavior analysis synergize to reveal hidden molecular linkages in the actin turnover cycle and cell signaling.
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Affiliation(s)
- Naoki Watanabe
- Department of Pharmacology, Kyoto University Faculty of Medicine, Yoshida Konoe-cho, Sakyo-ku, Kyoto, Japan.
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18
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Dominguez R. Actin filament nucleation and elongation factors--structure-function relationships. Crit Rev Biochem Mol Biol 2009; 44:351-66. [PMID: 19874150 DOI: 10.3109/10409230903277340] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The spontaneous and unregulated polymerization of actin filaments is inhibited in cells by actin monomer-binding proteins such as profilin and Tbeta4. Eukaryotic cells and certain pathogens use filament nucleators to stabilize actin polymerization nuclei, whose formation is rate-limiting. Known filament nucleators include the Arp2/3 complex and its large family of nucleation promoting factors (NPFs), formins, Spire, Cobl, VopL/VopF, TARP and Lmod. These molecules control the time and location for polymerization, and additionally influence the structures of the actin networks that they generate. Filament nucleators are generally unrelated, but with the exception of formins they all use the WASP-Homology 2 domain (WH2 or W), a small and versatile actin-binding motif, for interaction with actin. A common architecture, found in Spire, Cobl and VopL/VopF, consists of tandem W domains that bind three to four actin subunits to form a nucleus. Structural considerations suggest that NPFs-Arp2/3 complex can also be viewed as a specialized form of tandem W-based nucleator. Formins are unique in that they use the formin-homology 2 (FH2) domain for interaction with actin and promote not only nucleation, but also processive barbed end elongation. In contrast, the elongation function among W-based nucleators has been "outsourced" to a dedicated family of proteins, Eva/VASP, which are related to WASP-family NPFs.
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Affiliation(s)
- Roberto Dominguez
- Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6085, USA.
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Pujol N, Bonet C, Vilella F, Petkova MI, Mozo-Villarías A, de la Torre-Ruiz MA. Two proteins from Saccharomyces cerevisiae: Pfy1 and Pkc1, play a dual role in activating actin polymerization and in increasing cell viability in the adaptive response to oxidative stress. FEMS Yeast Res 2009; 9:1196-207. [PMID: 19765090 DOI: 10.1111/j.1567-1364.2009.00565.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In this work, we show that the proteins Pkc1 and Pfy1 play a role in the repolarization of the actin cytoskeleton and in cell survival in response to oxidative stress. We have also developed an assay to determine the actin polymerization capacity of total protein extracts using fluorescence recovery after photobleaching techniques and actin purified from rabbit muscle. This assay allowed us to demonstrate that Pfy1 promotes actin polymerization under conditions of oxidative stress, while Pkc1 induces actin polymerization and cell survival under all the conditions tested. Our assay also points to a relationship between Pkc1 and Pfy1 in the actin cytoskeleton polymerization that is required to adapt to oxidative stress.
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Affiliation(s)
- Nuria Pujol
- Department de Ciències Mèdiques Bàsiques-IRBLleida, Faculty of Medicine, University of Lleida, Lleida. Spain
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Qualmann B, Kessels MM. New players in actin polymerization--WH2-domain-containing actin nucleators. Trends Cell Biol 2009; 19:276-85. [PMID: 19406642 DOI: 10.1016/j.tcb.2009.03.004] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 02/24/2009] [Accepted: 03/09/2009] [Indexed: 01/07/2023]
Abstract
Actin nucleators promote the polymerization of the different types of actin arrays formed in a variety of cellular processes, such as cell migration, cellular morphogenesis and membrane trafficking processes. Several novel nucleators have been discovered recently. They all contain Wiskott-Aldrich syndrome protein (WASP) homology 2 (WH2 or W) domains for actin nucleation but seem to employ different molecular mechanisms and serve distinct cellular functions. Here, we summarize what is currently known about the different molecular mechanisms that Spire, Cordon-Bleu and Leiomodin seem to use and, also, the bacterial counterparts that mimic them (VopF, VopL and TARP). Recent studies on these WH2 proteins offer unique insight into the biological problem of actin-filament formation and how cells use specialized molecular machines to bring about so many different cytoskeletal structures.
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Affiliation(s)
- Britta Qualmann
- Institute for Biochemistry I, Friedrich-Schiller-University Jena, Nonnenplan 2, Jena, Germany
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Spire and Cordon-bleu: multifunctional regulators of actin dynamics. Trends Cell Biol 2008; 18:494-504. [PMID: 18774717 DOI: 10.1016/j.tcb.2008.07.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 06/27/2008] [Accepted: 07/03/2008] [Indexed: 12/20/2022]
Abstract
WASP-homology 2 (WH2) domains, which were first identified in the WASP/Scar (suppressor of cAMP receptor)/WAVE (WASP-family verprolin homologous protein) family of proteins, are multifunctional regulators of actin assembly. Two recently discovered actin-binding proteins, Spire and Cordon-bleu (Cobl), which have roles in axis patterning in developmental processes, use repeats of WH2 domains to generate a large repertoire of novel regulatory activities, including G-actin sequestration, actin-filament nucleation, filament severing and barbed-end dynamics regulation. We describe how these multiple functions selectively operate in a cellular context to control the dynamics of the actin cytoskeleton. In vivo, Spire and Cobl can synergize with other actin regulators. As an example, we outline potential methods to gain insight into the functional basis for reported genetic interactions among Spire, profilin and formin.
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22
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The actin cytoskeleton in cancer cell motility. Clin Exp Metastasis 2008; 26:273-87. [PMID: 18498004 DOI: 10.1007/s10585-008-9174-2] [Citation(s) in RCA: 427] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2008] [Accepted: 04/25/2008] [Indexed: 01/01/2023]
Abstract
Cancer cell metastasis is a multi-stage process involving invasion into surrounding tissue, intravasation, transit in the blood or lymph, extravasation, and growth at a new site. Many of these steps require cell motility, which is driven by cycles of actin polymerization, cell adhesion and acto-myosin contraction. These processes have been studied in cancer cells in vitro for many years, often with seemingly contradictory results. The challenge now is to understand how the multitude of in vitro observations relates to the movement of cancer cells in living tumour tissue. In this review we will concentrate on actin protrusion and acto-myosin contraction. We will begin by presenting some general principles summarizing the widely-accepted mechanisms for the co-ordinated regulation of actin polymerization and contraction. We will then discuss more recent studies that investigate how experimental manipulation of actin dynamics affects cancer cell invasion in complex environments and in vivo.
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