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Bai Y, Zhao F, Wu T, Chen F, Pang X. Actin polymerization and depolymerization in developing vertebrates. Front Physiol 2023; 14:1213668. [PMID: 37745245 PMCID: PMC10515290 DOI: 10.3389/fphys.2023.1213668] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 08/22/2023] [Indexed: 09/26/2023] Open
Abstract
Development is a complex process that occurs throughout the life cycle. F-actin, a major component of the cytoskeleton, is essential for the morphogenesis of tissues and organs during development. F-actin is formed by the polymerization of G-actin, and the dynamic balance of polymerization and depolymerization ensures proper cellular function. Disruption of this balance results in various abnormalities and defects or even embryonic lethality. Here, we reviewed recent findings on the structure of G-actin and F-actin and the polymerization of G-actin to F-actin. We also focused on the functions of actin isoforms and the underlying mechanisms of actin polymerization/depolymerization in cellular and organic morphogenesis during development. This information will extend our understanding of the role of actin polymerization in the physiologic or pathologic processes during development and may open new avenues for developing therapeutics for embryonic developmental abnormalities or tissue regeneration.
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Affiliation(s)
- Yang Bai
- Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
| | - Feng Zhao
- Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
| | - Tingting Wu
- Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
| | - Fangchun Chen
- Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
| | - Xiaoxiao Pang
- Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China
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Ma S, Yu H, Wang M, Cui T, Zhao Y, Zhang X, Wang C, Li M, Zhang L, Dong J. Natural product drupacine acting on a novel herbicidal target shikimate dehydrogenase. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 194:105480. [PMID: 37532346 DOI: 10.1016/j.pestbp.2023.105480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/18/2023] [Accepted: 05/23/2023] [Indexed: 08/04/2023]
Abstract
Natural products are one of the important sources for the creation of new pesticides. Drupacine ((1R,11S,12S,13R,15S)-13-methoxy-5,7,21-trioxa-19-azahexacyclo[11.7.1.02,10.04,8.011,15.015,19]henicosa-2,4(8),9-trien-12-ol), isolated from Cephalotaxus sinensis (Chinese plum-yew), is a potent herbicidal compound containing an oxo-bridged oxygen bond structure. However, its molecular target still remains unknown. In this study, the targets of drupacine in Amaranthus retroflexus were identified by combining drug affinity responsive target stability (DARTS), cellular thermal shift assay coupled with mass spectrometry (CETSA MS), RNA-seq transcriptomic, and TMT proteomic analyses. Fifty-one and sixty-eight main binding proteins were identified by DARTS and CETSA MS, respectively, including nine co-existing binding proteins. In drupacine-treated A. retroflexus seedlings we identified 1389 up-regulated genes and 442 down-regulated genes, 34 up-regulated proteins, and 194 down-regulated proteins, respectively. Combining the symptoms and the biochemical profiles, Profilin, Shikimate dehydrogenase (SkDH), and Zeta-carotene desaturase were predicted to be the drupacine potential target proteins. At the same time, drupacine was found to bind SkDH stronger by molecular docking, and its inhibition on ArSkDH increased with the treatment concentration increase. Our results suggest that the molecular target of drupacine is SkDH, a new herbicide target, which lay a foundation for the rational design of herbicides based on new targets from natural products and enrich the target resources for developing green herbicides.
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Affiliation(s)
- Shujie Ma
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China.
| | - Hualong Yu
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
| | - Mingyu Wang
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
| | - Tingru Cui
- Baoding Meteorological Bureau, Baoding 071000, China
| | - Yujing Zhao
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
| | - Xinxin Zhang
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
| | - Caixia Wang
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
| | - Mengmeng Li
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China
| | - Lihui Zhang
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China.
| | - Jingao Dong
- State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology/College of Plant Protection, Hebei Agricultural University, Baoding 071000, China.
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Actin depolymerizing factor ADF7 inhibits actin bundling protein VILLIN1 to regulate root hair formation in response to osmotic stress in Arabidopsis. PLoS Genet 2022; 18:e1010338. [PMID: 36095000 PMCID: PMC9499291 DOI: 10.1371/journal.pgen.1010338] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 09/22/2022] [Accepted: 07/12/2022] [Indexed: 11/25/2022] Open
Abstract
Actin cytoskeleton is essential for root hair formation. However, the underlying molecular mechanisms of actin dynamics in root hair formation in response to abiotic stress are largely undiscovered. Here, genetic analysis showed that actin-depolymerizing protein ADF7 and actin-bundling protein VILLIN1 (VLN1) were positively and negatively involved in root hair formation of Arabidopsis respectively. Moreover, RT-qPCR, GUS staining, western blotting, and genetic analysis revealed that ADF7 played an important role in inhibiting the expression and function of VLN1 during root hair formation. Filament actin (F-actin) dynamics observation and actin pharmacological experiments indicated that ADF7-inhibited-VLN1 pathway led to the decline of F-actin bundling and thick bundle formation, as well as the increase of F-actin depolymerization and turnover to promote root hair formation. Furthermore, the F-actin dynamics mediated by ADF7-inhibited-VLN1 pathway was associated with the reactive oxygen species (ROS) accumulation in root hair formation. Finally, ADF7-inhibited-VLN1 pathway was critical for osmotic stress-induced root hair formation. Our work demonstrates that ADF7 inhibits VLN1 to regulate F-actin dynamics in root hair formation in response to osmotic stress, providing the novel evidence on the F-actin dynamics and their molecular mechanisms in root hair formation and in abiotic stress. Root hairs are required for plants to absorb nutrients and water. The dynamics of cytoskeleton such as actin filaments (F-actin) are necessary for the formation of root hairs, which is regulated by different kinds of cytoskeleton-binding proteins. At the same time, the dynamics of cytoskeleton are also involved in plant abiotic stress tolerance. However, there are few studies on the underlying molecular mechanisms of F-actin dynamics in root hair formation in response to abiotic stress. Actin depolymerization factor 7 (ADF7) and actin bunding protein Villin 1 (VLN1) are important actin-binding proteins in Arabidopsis. Here, we describe a pathway that ADF7 inhibits VLN1 to regulate F-actin dynamics in root hair formation in response to osmotic stress, providing a new evidence for the studies on the molecular mechanisms of F-actin dynamics in root hair formation and in plant abiotic stress tolerance.
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Sun J, Zhong X, Fu X, Miller H, Lee P, Yu B, Liu C. The Actin Regulators Involved in the Function and Related Diseases of Lymphocytes. Front Immunol 2022; 13:799309. [PMID: 35371070 PMCID: PMC8965893 DOI: 10.3389/fimmu.2022.799309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 02/01/2022] [Indexed: 11/21/2022] Open
Abstract
Actin is an important cytoskeletal protein involved in signal transduction, cell structure and motility. Actin regulators include actin-monomer-binding proteins, Wiskott-Aldrich syndrome (WAS) family of proteins, nucleation proteins, actin filament polymerases and severing proteins. This group of proteins regulate the dynamic changes in actin assembly/disassembly, thus playing an important role in cell motility, intracellular transport, cell division and other basic cellular activities. Lymphocytes are important components of the human immune system, consisting of T-lymphocytes (T cells), B-lymphocytes (B cells) and natural killer cells (NK cells). Lymphocytes are indispensable for both innate and adaptive immunity and cannot function normally without various actin regulators. In this review, we first briefly introduce the structure and fundamental functions of a variety of well-known and newly discovered actin regulators, then we highlight the role of actin regulators in T cell, B cell and NK cell, and finally provide a landscape of various diseases associated with them. This review provides new directions in exploring actin regulators and promotes more precise and effective treatments for related diseases.
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Affiliation(s)
- Jianxuan Sun
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Department and Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xingyu Zhong
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoyu Fu
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Heather Miller
- Cytek Biosciences, R&D Clinical Reagents, Fremont, CA, United States
| | - Pamela Lee
- Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Bing Yu
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chaohong Liu
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Gao J, Nakamura F. Actin-Associated Proteins and Small Molecules Targeting the Actin Cytoskeleton. Int J Mol Sci 2022; 23:ijms23042118. [PMID: 35216237 PMCID: PMC8880164 DOI: 10.3390/ijms23042118] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 02/06/2023] Open
Abstract
Actin-associated proteins (AAPs) act on monomeric globular actin (G-actin) and polymerized filamentous actin (F-actin) to regulate their dynamics and architectures which ultimately control cell movement, shape change, division; organelle localization and trafficking. Actin-binding proteins (ABPs) are a subset of AAPs. Since actin was discovered as a myosin-activating protein (hence named actin) in 1942, the protein has also been found to be expressed in non-muscle cells, and numerous AAPs continue to be discovered. This review article lists all of the AAPs discovered so far while also allowing readers to sort the list based on the names, sizes, functions, related human diseases, and the dates of discovery. The list also contains links to the UniProt and Protein Atlas databases for accessing further, related details such as protein structures, associated proteins, subcellular localization, the expression levels in cells and tissues, mutations, and pathology. Because the actin cytoskeleton is involved in many pathological processes such as tumorigenesis, invasion, and developmental diseases, small molecules that target actin and AAPs which hold potential to treat these diseases are also listed.
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Boraldi F, Lofaro FD, Bergamini G, Ferrari A, Malagoli D. Pomacea canaliculata Ampullar Proteome: A Nematode-Based Bio-Pesticide Induces Changes in Metabolic and Stress-Related Pathways. BIOLOGY 2021; 10:1049. [PMID: 34681148 PMCID: PMC8533556 DOI: 10.3390/biology10101049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 12/17/2022]
Abstract
Pomacea canaliculata is a freshwater gastropod known for being both a highly invasive species and one of the possible intermediate hosts of the mammalian parasite Angiostrongylus cantonensis. With the aim of providing new information concerning P. canaliculata biology and adaptability, the first proteome of the ampulla, i.e., a small organ associated with the circulatory system and known as a reservoir of nitrogen-containing compounds, was obtained. The ampullar proteome was derived from ampullae of control snails or after exposure to a nematode-based molluscicide, known for killing snails in a dose- and temperature-dependent fashion. Proteome analysis revealed that the composition of connective ampulla walls, cell metabolism and oxidative stress response were affected by the bio-pesticide. Ultrastructural investigations have highlighted the presence of rhogocytes within the ampullar walls, as it has been reported for other organs containing nitrogen storage tissue. Collected data suggested that the ampulla may belong to a network of organs involved in controlling and facing oxidative stress in different situations. The response against the nematode-based molluscicide recalled the response set up during early arousal after aestivation and hibernation, thus encouraging the hypothesis that metabolic pathways and antioxidant defences promoting amphibiousness could also prove useful in facing other challenges stimulating an oxidative stress response, e.g., immune challenges or biocide exposure. Targeting the oxidative stress resistance of P. canaliculata may prove helpful for increasing its susceptibility to bio-pesticides and may help the sustainable control of this pest's diffusion.
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Affiliation(s)
- Federica Boraldi
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.D.L.); (A.F.)
| | - Francesco Demetrio Lofaro
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.D.L.); (A.F.)
| | - Giulia Bergamini
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy;
| | - Agnese Ferrari
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.D.L.); (A.F.)
| | - Davide Malagoli
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy; (F.D.L.); (A.F.)
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Adaptor SH3BGRL promotes breast cancer metastasis through PFN1 degradation by translational STUB1 upregulation. Oncogene 2021; 40:5677-5690. [PMID: 34331014 DOI: 10.1038/s41388-021-01970-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 07/11/2021] [Accepted: 07/19/2021] [Indexed: 02/07/2023]
Abstract
Metastatic recurrence is still a major challenge in breast cancer treatment, but the underlying mechanisms remain unclear. Here, we report that a small adaptor protein, SH3BGRL, is upregulated in the majority of breast cancer patients, especially elevated in those with metastatic relapse, indicating it as a marker for the poor prognosis of breast cancer. Physiologically, SH3BGRL can multifunctionally promote breast cancer cell tumorigenicity, migration, invasiveness, and efficient lung colonization in nude mice. Mechanistically, SH3BGRL downregulates the acting-binding protein profilin 1 (PFN1) by accelerating the translation of the PFN1 E3 ligase, STUB1 via SH3BGRL interaction with ribosomal proteins, or/and enhancing the interaction of PFN1 with STUB1 to accelerate PFN1 degradation. Loss of PFN1 consequently contributes to downstream multiple activations of AKT, NF-kB, and WNT signaling pathways. In contrast, the forced expression of compensatory PFN1 in SH3BGRL-high cells efficiently neutralizes SH3BGRL-induced metastasis and tumorigenesis with PTEN upregulation and PI3K-AKT signaling inactivation. Clinical analysis validates that SH3BGRL expression is negatively correlated with PFN1 and PTEN levels, but positively to the activations of AKT, NF-kB, and WNT signaling pathways in breast patient tissues. Our results thus suggest that SH3BGRL is a valuable prognostic factor and a potential therapeutic target for preventing breast cancer progression and metastasis.
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Janssen E, Geha RS. Primary immunodeficiencies caused by mutations in actin regulatory proteins. Immunol Rev 2019; 287:121-134. [PMID: 30565251 DOI: 10.1111/imr.12716] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 08/31/2018] [Indexed: 12/31/2022]
Abstract
The identification of patients with monogenic gene defects have illuminated the function of different proteins in the immune system, including proteins that regulate the actin cytoskeleton. Many of these actin regulatory proteins are exclusively expressed in leukocytes and regulate the formation and branching of actin filaments. Their absence or abnormal function leads to defects in immune cell shape, cellular projections, migration, and signaling. Through the study of patients' mutations and generation of mouse models that recapitulate the patients' phenotypes, our laboratory and others have gained a better understanding of the role these proteins play in cell biology and the underlying pathogenesis of immunodeficiencies and immune dysregulatory syndromes.
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Affiliation(s)
- Erin Janssen
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Raif S Geha
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
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Ding X, Zhang S, Liu J, Liu S, Su H. Arabidopsis FIM4 and FIM5 regulates the growth of root hairs in an auxin-insensitive way. PLANT SIGNALING & BEHAVIOR 2018; 13:e1473667. [PMID: 30148414 PMCID: PMC6204792 DOI: 10.1080/15592324.2018.1473667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
Tip-growing cells provide a useful model system for studying the underlying mechanisms of plant cell growth. The apical growth of root hairs is dependent on the microfilament skeleton, and auxin is an important regulator of root hair development. We functionally characterized actin bundling proteins AtFIM4 and AtFIM5, which were preferentially expressed in tip-growing cells such as pollen tubes and root hairs. The morphology and length of root hairs in atfim4/atfim5 double mutant line had obvious defects. In addition, we found the growth of root hairs of atfim4/atfim5 double mutant was insensitive to exogenous IAA (indole-3-acetic acid) treatment. So we consider that AtFIM4 and AtFIM5 act together to regulate the growth of root hair in an auxin-insensitive way.
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Affiliation(s)
- X. Ding
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
| | - S. Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
| | - J. Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
| | - S. Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
| | - H. Su
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, School of Life Sciences, Northwest University, Xi’an, China
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Skruber K, Read TA, Vitriol EA. Reconsidering an active role for G-actin in cytoskeletal regulation. J Cell Sci 2018; 131:131/1/jcs203760. [PMID: 29321224 DOI: 10.1242/jcs.203760] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Globular (G)-actin, the actin monomer, assembles into polarized filaments that form networks that can provide structural support, generate force and organize the cell. Many of these structures are highly dynamic and to maintain them, the cell relies on a large reserve of monomers. Classically, the G-actin pool has been thought of as homogenous. However, recent work has shown that actin monomers can exist in distinct groups that can be targeted to specific networks, where they drive and modify filament assembly in ways that can have profound effects on cellular behavior. This Review focuses on the potential factors that could create functionally distinct pools of actin monomers in the cell, including differences between the actin isoforms and the regulation of G-actin by monomer binding proteins, such as profilin and thymosin β4. Owing to difficulties in studying and visualizing G-actin, our knowledge over the precise role that specific actin monomer pools play in regulating cellular actin dynamics remains incomplete. Here, we discuss some of these unanswered questions and also provide a summary of the methodologies currently available for the imaging of G-actin.
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Affiliation(s)
- Kristen Skruber
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
| | - Tracy-Ann Read
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
| | - Eric A Vitriol
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
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Overexpression of GhPFN2 enhances protection against Verticillium dahliae invasion in cotton. SCIENCE CHINA-LIFE SCIENCES 2017; 60:861-867. [PMID: 28741129 DOI: 10.1007/s11427-017-9067-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/03/2017] [Indexed: 12/12/2022]
Abstract
Growing evidence indicates that actin cytoskeleton is involved in plant innate immune responses, but the functional mechanism remains largely unknown. Here, we investigated the behavior of a cotton profilin gene (GhPFN2) in response to Verticillium dahliae invasion, and evaluated its contribution to plant defense against this soil-borne fungal pathogen. GhPFN2 expression was up-regulated when cotton root was inoculated with V. dahliae, and the actin architecture was reorganized in the infected root cells, with a clear increase in the density of filamentous actin and the extent of actin bundling. Compared to the wild type, GhPFN2-overexpressing cotton plants showed enhanced protection against V. dahliae infection and the actin cytoskeleton organization in root epidermal cells was clearly altered, which phenocopied that of the wild-type (WT) root cells challenged with V. dahliae. These results provide a solid line of evidence showing that actin cytoskeleton reorganization involving GhPFN2 is important for defense against V. dahliae infection.
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12
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Del Poggetto E, Gori L, Chiti F. Biophysical analysis of three novel profilin-1 variants associated with amyotrophic lateral sclerosis indicates a correlation between their aggregation propensity and the structural features of their globular state. Biol Chem 2017; 397:927-37. [PMID: 27101547 DOI: 10.1515/hsz-2016-0154] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 04/14/2016] [Indexed: 11/15/2022]
Abstract
Profilin-1 is a small protein involved in actin-mediated cytoskeleton rearrangement. Recently, mutations of profilin-1 have been associated with familial amyotrophic lateral sclerosis. It was previously reported that pathogenic mutations of profilin-1 increase the aggregation propensity of this protein, leaving its function unaffected. However, it is not clear if the mutations act by decreasing the conformational stability or by promoting structural perturbations of the folded state of this protein. In this work we have purified three novel profilin-1 mutants that were recently discovered and have investigated their conformational stability, structural features and aggregation behaviour in vitro. Analysis of the data obtained with the three novel variants, and a global statistical analysis with all profilin-1 mutants so far characterised, indicate significant correlations between aggregation propensity and structural perturbations of the folded state, rather than its conformational stability, in this group of mutants.
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Evolutionary expansion and structural functionalism of the ancient family of profilin proteins. Gene 2017; 626:70-86. [PMID: 28501628 DOI: 10.1016/j.gene.2017.05.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 05/02/2017] [Accepted: 05/09/2017] [Indexed: 02/07/2023]
Abstract
Structure and functional similarities of a recent protein's orthologs with its ancient counterpart are largely determined by the configuration of evolutionary preservation of amino acids. The emergence of genome sequencing databases allowed dissecting the evolutionarily important gene families at a comprehensive and genome-wide scale. The profilin multi-gene family is an ancient, universal, and functionally diverged across kingdoms, which regulates various aspects of cellular development in both prokarya and eukarya, especially cell-wall maintenance through actin sequestering, nucleation and cytokinesis. We performed a meta-analysis of the evolutionary expansion, structural conservation, evolution of function motifs, and transcriptional biases of profilin proteins across kingdoms. An exhaustive search of various genome databases of cyanobacteria, fungi, animalia and plantae kingdoms revealed 172 paralogous/orthologous profilins those were phylogenetically clustered in various groups. Orthologous gene comparisons indicated that segmental and tandem duplication events under strong purifying selection are predominantly responsible for their convoluted structural divergences. Evidently, structural divergences were more prevalent in the paralogs than orthologs, and evolutionary variations in the exon/intron architecture were accomplished by 'exon/intron-gain' and insertion/deletion during sequence-exonization. Remarkably, temporal expression evolution of profilin paralogs/homeologs during cotton fiber domestication provides evolutionary impressions of the selection of highly diverged transcript abundance notably in the fiber morpho-evolution. These results provide global insights into the profilin evolution, their structural design across taxa; and their future utilization in translational research.
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Fields PA, Burmester EM, Cox KM, Karch KR. Rapid proteomic responses to a near-lethal heat stress in the salt marsh mussel Geukensia demissa. ACTA ACUST UNITED AC 2016; 219:2673-86. [PMID: 27335449 DOI: 10.1242/jeb.141176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/17/2016] [Indexed: 01/27/2023]
Abstract
Acute heat stress perturbs cellular function on a variety of levels, leading to protein dysfunction and aggregation, oxidative stress and loss of metabolic homeostasis. If these challenges are not overcome quickly, the stressed organism can die. To better understand the earliest tissue-level responses to heat stress, we examined the proteomic response of gill from Geukensia demissa, an extremely eurythermal mussel from the temperate intertidal zone of eastern North America. We exposed 15°C-acclimated individuals to an acute near-lethal heat stress (45°C) for 1 h, and collected gill samples from 0 to 24 h of recovery. The changes in protein expression we found reveal a coordinated physiological response to acute heat stress: proteins associated with apoptotic processes were increased in abundance during the stress itself (i.e. at 0 h of recovery), while protein chaperones and foldases increased in abundance soon after (3 h). The greatest number of proteins changed abundance at 6 h; these included oxidative stress proteins and enzymes of energy metabolism. Proteins associated with the cytoskeleton and extracellular matrix also changed in abundance starting at 6 h, providing evidence of cell proliferation, migration and tissue remodeling. By 12 h, the response to acute heat stress was diminishing, with fewer stress and structural proteins changing in abundance. Finally, the proteins with altered abundances identified at 24 h suggest a return to the pre-stress anabolic state.
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Affiliation(s)
- Peter A Fields
- Biology Department, Franklin & Marshall College, Lancaster, PA 17603, USA
| | | | - Kelly M Cox
- Biology Department, Franklin & Marshall College, Lancaster, PA 17603, USA
| | - Kelly R Karch
- Biology Department, Franklin & Marshall College, Lancaster, PA 17603, USA
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15
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Pernier J, Shekhar S, Jegou A, Guichard B, Carlier MF. Profilin Interaction with Actin Filament Barbed End Controls Dynamic Instability, Capping, Branching, and Motility. Dev Cell 2016; 36:201-14. [PMID: 26812019 PMCID: PMC4729542 DOI: 10.1016/j.devcel.2015.12.024] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/09/2015] [Accepted: 12/22/2015] [Indexed: 12/22/2022]
Abstract
Cell motility and actin homeostasis depend on the control of polarized growth of actin filaments. Profilin, an abundant regulator of actin dynamics, supports filament assembly at barbed ends by binding G-actin. Here, we demonstrate how, by binding and destabilizing filament barbed ends at physiological concentrations, profilin also controls motility, cell migration, and actin homeostasis. Profilin enhances filament length fluctuations. Profilin competes with Capping Protein at barbed ends, which generates a lower amount of profilin-actin than expected if barbed ends were tightly capped. Profilin competes with barbed end polymerases, such as formins and VopF, and inhibits filament branching by WASP-Arp2/3 complex by competition for filament barbed ends, accounting for its as-yet-unknown effects on motility and metastatic cell migration observed in this concentration range. In conclusion, profilin is a major coordinator of polarized growth of actin filaments, controlled by competition between barbed end cappers, trackers, destabilizers, and filament branching machineries. The binding of profilin to barbed ends accounts for its effects on cell migration Profilin enhances length fluctuations of actin filaments by destabilizing barbed ends Profilin competes with capping protein at filament barbed ends Profilin competes with polymerases and filament branching machineries at barbed ends
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Affiliation(s)
- Julien Pernier
- Cytoskeleton Dynamics and Motility Group, I2BC, CNRS, Gif-sur-Yvette 91198, France
| | - Shashank Shekhar
- Cytoskeleton Dynamics and Motility Group, I2BC, CNRS, Gif-sur-Yvette 91198, France
| | - Antoine Jegou
- Cytoskeleton Dynamics and Motility Group, I2BC, CNRS, Gif-sur-Yvette 91198, France
| | - Bérengère Guichard
- Cytoskeleton Dynamics and Motility Group, I2BC, CNRS, Gif-sur-Yvette 91198, France
| | - Marie-France Carlier
- Cytoskeleton Dynamics and Motility Group, I2BC, CNRS, Gif-sur-Yvette 91198, France.
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16
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Abstract
Seven decades of research have revealed much about actin structure, assembly, regulatory proteins, and cellular functions. However, some key information is still missing, so we do not understand the mechanisms of most processes that depend on actin. This chapter summarizes our current knowledge and explains some examples of work that will be required to fill these gaps and arrive at a mechanistic understanding of actin biology.
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Affiliation(s)
- Thomas D Pollard
- Department of Molecular Cellular and Developmental Biology, Yale University, 208103, New Haven, CT, 06520-8103, USA. .,Department of Molecular Biophysics and Biochemistry, Yale University, 208103, New Haven, CT, 06520-8103, USA. .,Department of Cell Biology, Yale University, 208103, New Haven, CT, 06520-8103, USA.
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17
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Del Poggetto E, Bemporad F, Tatini F, Chiti F. Mutations of Profilin-1 Associated with Amyotrophic Lateral Sclerosis Promote Aggregation Due to Structural Changes of Its Native State. ACS Chem Biol 2015; 10:2553-63. [PMID: 26226631 DOI: 10.1021/acschembio.5b00598] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The PFN1 gene, coding for profilin-1, has recently been associated with familial amyotrophic lateral sclerosis (fALS), as three mutations, namely C71G, M114T, and G118V, have been found in patients with familial forms of the disease and another, E117G, has been proposed to be a moderate risk factor for disease onset. In this work, we have purified the four profilin-1 variants along with the wild-type protein. The resulting aggregates appear to be fibrillar, to have a weak binding to ThT, and to possess a significant amount of intermolecular β-sheet structure. Using ThT fluorescence assays, far-UV circular dichroism, and dynamic light scattering, we found that all four variants have an aggregation propensity higher than that of the wild-type counterpart. In particular, the C71G mutation was found to induce the most dramatic change in aggregation, followed by the G118V and M114T substitutions and then the E117G mutation. Such a propensity was found not to strictly correlate with the conformational stability in this group of profilin-1 variants, determined using both urea-induced denaturation at equilibrium and folding/unfolding kinetics. However, it correlated with structural changes of the folded states, as monitored with far-UV circular dichroism, intrinsic fluorescence spectroscopy, ANS binding, acrylamide quenching, and dynamic light scattering. Overall, the results suggest that all four mutations increase the tendency of profilin-1 to aggregate and that such aggregation behavior is largely determined by the mutation-induced structural changes occurring in the folded state of the protein.
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Affiliation(s)
- Edoardo Del Poggetto
- Department
of Biomedical Experimental and Clinical Sciences, Section of Biochemistry, University of Florence, Viale Morgagni 50, I-50134, Florence, Italy
| | - Francesco Bemporad
- Department
of Biomedical Experimental and Clinical Sciences, Section of Biochemistry, University of Florence, Viale Morgagni 50, I-50134, Florence, Italy
| | - Francesca Tatini
- Institute
of Applied Physics Nello Carrara, National Research Council, Via
Madonna del Piano 10, I-50019, Sesto Fiorentino (FI), Italy
| | - Fabrizio Chiti
- Department
of Biomedical Experimental and Clinical Sciences, Section of Biochemistry, University of Florence, Viale Morgagni 50, I-50134, Florence, Italy
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18
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Actin, actin-related proteins and profilin in diatoms: A comparative genomic analysis. Mar Genomics 2015; 23:133-42. [DOI: 10.1016/j.margen.2015.07.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 06/30/2015] [Accepted: 07/02/2015] [Indexed: 12/24/2022]
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The Folding process of Human Profilin-1, a novel protein associated with familial amyotrophic lateral sclerosis. Sci Rep 2015; 5:12332. [PMID: 26227615 PMCID: PMC4521207 DOI: 10.1038/srep12332] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 06/17/2015] [Indexed: 12/11/2022] Open
Abstract
Human profilin-1 is a novel protein associated with a recently discovered form of familial amyotrophic lateral sclerosis. This urges the characterization of possible conformational states, different from the fully folded state, potentially able to initiate self-assembly. Under native conditions, profilin-1 is monomeric and possesses a well-defined secondary and tertiary structure. When incubated at low pH or with high urea concentrations, profilin-1 remains monomeric but populates unfolded states exhibiting larger hydrodynamic radius and disordered structure, as assessed by dynamic light scattering, far-UV circular dichroism and intrinsic fluorescence. Refolding from the urea-unfolded state was studied at equilibrium and in real-time using a stopped-flow apparatus. The results obtained with intrinsic fluorescence and circular dichroism indicate a single phase without significant changes of the corresponding signals before the major refolding transition. However, such a transition is preceded by a burst phase with an observed increase of ANS fluorescence, which indicates the conversion into a transiently populated collapsed state possessing solvent-exposed hydrophobic clusters. Kinetic analysis reveals that such state has a conformational stability comparable to that of the fully unfolded state. To our knowledge, profilin-1 is the first example of an amyloid-related protein where folding occurs in the absence of thermodynamically stable partially folded states.
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Structural basis of thymosin-β4/profilin exchange leading to actin filament polymerization. Proc Natl Acad Sci U S A 2014; 111:E4596-605. [PMID: 25313062 PMCID: PMC4217450 DOI: 10.1073/pnas.1412271111] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Thymosin-β4 (Tβ4) and profilin are the two major sequestering proteins that maintain the pool of monomeric actin (G-actin) within cells of higher eukaryotes. Tβ4 prevents G-actin from joining a filament, whereas profilin:actin only supports barbed-end elongation. Here, we report two Tβ4:actin structures. The first structure shows that Tβ4 has two helices that bind at the barbed and pointed faces of G-actin, preventing the incorporation of the bound G-actin into a filament. The second structure displays a more open nucleotide binding cleft on G-actin, which is typical of profilin:actin structures, with a concomitant disruption of the Tβ4 C-terminal helix interaction. These structures, combined with biochemical assays and molecular dynamics simulations, show that the exchange of bound actin between Tβ4 and profilin involves both steric and allosteric components. The sensitivity of profilin to the conformational state of actin indicates a similar allosteric mechanism for the dissociation of profilin during filament elongation.
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21
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Ramaiola I, Padró T, Peña E, Juan-Babot O, Cubedo J, Martin-Yuste V, Sabate M, Badimon L. Changes in thrombus composition and profilin-1 release in acute myocardial infarction. Eur Heart J 2014; 36:965-75. [PMID: 25217443 DOI: 10.1093/eurheartj/ehu356] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 08/08/2014] [Indexed: 12/11/2022] Open
Abstract
AIM Thrombus formation is a dynamic process regulated by flow, blood cells, and plasma proteins. The present study was performed to investigate the characteristics of human coronary thrombus in ST-segment elevation myocardial infarction (STEMI). METHODS AND RESULTS Patients admitted with ST-elevation myocardial infarction, in which thrombectomy was performed, were included (n = 86). Intracoronary thrombi and blood from the culprit coronary site and the systemic circulation were obtained during percutaneous coronary intervention (PCI). Thrombi were categorized by onset-of-pain-to-PCI elapsed time in thrombus of <3 (T3) and more than 6 h of evolution (T6). Clinical, morphological, and proteomic variables were investigated. While T3 were mainly composed by platelets and fibrin(ogen), T6 were characterized by a reduced platelet content, increased leucocytes infiltration (including monocytes, neutrophils, T-cells, and B-cells), and appearance of undifferentiated progenitor cells. Significant differences between T3 and T6 were found in the cell cytoskeleton-associated proteome (beta-actin and tropomyosin 3 and 4). By discovery proteomics, we have identified profilin-1 (Pfn-1) in the coronary thrombi and detected higher levels in T3 than in T6. While plasma Pfn-1 levels were low in T3 patients, levels significantly increased in both coronary and peripheral circulation in T6 patients indicating release. In vitro platelet aggregation studies showed that platelets secrete Pfn-1 upon complete activation. CONCLUSION Coronary thrombi show rapid dynamic changes both in structure and cell composition as a function of elapsed onset-of-pain-to-PCI time. Aged ischaemic thrombi were more likely to have reduced Pfn-1 content releasing Pfn-1 to the circulation. Onset-of-pain-to-PCI elapsed time in STEMI patients and hence age of occlusive thrombus can be profiled by Pfn-1 levels found in the peripheral circulation.
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Affiliation(s)
- Ilaria Ramaiola
- Cardiovascular Research Center (CSIC-ICCC), IIB SantPau, c/Sant Antoni Mª Claret 167, 08025 Barcelona, Spain
| | - Teresa Padró
- Cardiovascular Research Center (CSIC-ICCC), IIB SantPau, c/Sant Antoni Mª Claret 167, 08025 Barcelona, Spain
| | - Esther Peña
- Cardiovascular Research Center (CSIC-ICCC), IIB SantPau, c/Sant Antoni Mª Claret 167, 08025 Barcelona, Spain
| | - Oriol Juan-Babot
- Cardiovascular Research Center (CSIC-ICCC), IIB SantPau, c/Sant Antoni Mª Claret 167, 08025 Barcelona, Spain
| | - Judit Cubedo
- Cardiovascular Research Center (CSIC-ICCC), IIB SantPau, c/Sant Antoni Mª Claret 167, 08025 Barcelona, Spain
| | | | | | - Lina Badimon
- Cardiovascular Research Center (CSIC-ICCC), IIB SantPau, c/Sant Antoni Mª Claret 167, 08025 Barcelona, Spain Cardiovascular Research Chair UAB, Barcelona, Spain
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22
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Abstract
WIP plays an important role in the remodeling of the actin cytoskeleton, which controls cellular activation, proliferation, and function. WIP regulates actin polymerization by linking the actin machinery to signaling cascades. WIP binding to WASp and to its homolog, N-WASp, which are central activators of the actin-nucleating complex Arp2/3, regulates their cellular distribution, function, and stability. By binding to WASp, WIP protects it from degradation and thus, is crucial for WASp retention. Indeed, most mutations that result in WAS, an X-linked immunodeficiency caused by defective/absent WASp activity, are located in the WIP-binding region of WASp. In addition, by binding directly to actin, WIP promotes the formation and stabilization of actin filaments. WASp-independent activities of WIP constitute a new research frontier and are discussed extensively in this article. Here, we review the current information on WIP in human and mouse systems, focusing on its associated proteins, its molecular-regulatory mechanisms, and its role as a key regulator of actin-based processes in the immune system.
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Affiliation(s)
- Sophia Fried
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Omri Matalon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Elad Noy
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Mira Barda-Saad
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
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23
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Choi YN, Lee SK, Seo TW, Lee JS, Yoo SJ. C-terminus of Hsc70-interacting protein regulates profilin1 and breast cancer cell migration. Biochem Biophys Res Commun 2014; 446:1060-6. [DOI: 10.1016/j.bbrc.2014.03.061] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 03/15/2014] [Indexed: 10/25/2022]
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24
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Girdler GC, Röper K. Controlling cell shape changes during salivary gland tube formation in Drosophila. Semin Cell Dev Biol 2014; 31:74-81. [PMID: 24685610 DOI: 10.1016/j.semcdb.2014.03.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 03/18/2014] [Indexed: 12/23/2022]
Abstract
Any type of tubulogenesis is a process that is highly coordinated between large numbers of cells. Like other morphogenetic processes, it is driven to a great extent by complex cell shape changes and cell rearrangements. The formation of the salivary glands in the fly embryo provides an ideal model system to study these changes and rearrangements, because upon specification of the cells that are destined to form the tube, there is no further cell division or cell death. Thus, morphogenesis of the salivary gland tubes is entirely driven by cell shape changes and rearrangements. In this review, we will discuss and distill from the literature what is known about the control of cell shape during the early invagination process and whilst the tubes extend in the fly embryo at later stages.
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Affiliation(s)
- Gemma C Girdler
- MRC-Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Katja Röper
- MRC-Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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25
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Kang H, Bradley MJ, Elam WA, De La Cruz EM. Regulation of actin by ion-linked equilibria. Biophys J 2013; 105:2621-8. [PMID: 24359734 PMCID: PMC3882474 DOI: 10.1016/j.bpj.2013.10.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 10/25/2013] [Accepted: 10/29/2013] [Indexed: 11/22/2022] Open
Abstract
Actin assembly, filament mechanical properties, and interactions with regulatory proteins depend on the types and concentrations of salts in solution. Salts modulate actin through both nonspecific electrostatic effects and specific binding to discrete sites. Multiple cation-binding site classes spanning a broad range of affinities (nanomolar to millimolar) have been identified on actin monomers and filaments. This review focuses on discrete, low-affinity cation-binding interactions that drive polymerization, regulate filament-bending mechanics, and modulate interactions with regulatory proteins. Cation binding may be perturbed by actin post-translational modifications and linked equilibria. Partial cation occupancy under physiological and commonly used in vitro solution conditions likely contribute to filament mechanical heterogeneity and structural polymorphism. Site-specific cation-binding residues are conserved in Arp2 and Arp3, and may play a role in Arp2/3 complex activation and actin-filament branching activity. Actin-salt interactions demonstrate the relevance of ion-linked equilibria in the operation and regulation of complex biological systems.
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Affiliation(s)
- Hyeran Kang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Michael J Bradley
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - W Austin Elam
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut.
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Guo Z, Stephenson R, Qiu J, Zheng S, Luo ZQ. A Legionella effector modulates host cytoskeletal structure by inhibiting actin polymerization. Microbes Infect 2013; 16:225-36. [PMID: 24286927 DOI: 10.1016/j.micinf.2013.11.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 12/21/2022]
Abstract
Successful infection by the opportunistic pathogen Legionella pneumophila requires the collective activity of hundreds of virulence proteins delivered into the host cell by the Dot/Icm type IV secretion system. These virulence proteins, also called effectors modulate distinct host cellular processes to create a membrane-bound niche called the Legionella containing vacuole (LCV) supportive of bacterial growth. We found that Ceg14 (Lpg0437), a Dot/Icm substrate is toxic to yeast and such toxicity can be alleviated by overexpression of profilin, a protein involved in cytoskeletal structure in eukaryotes. We further showed that mutations in profilin affect actin binding but not other functions such as interactions with poly-l-proline or phosphatidylinositol, abolish its suppressor activity. Consistent with the fact the profilin suppresses its toxicity, expression of Ceg14 but not its non-toxic mutants in yeast affects actin distribution and budding of daughter cells. Although Ceg14 does not detectably interact with profilin, it co-sediments with filamentous actin and inhibits actin polymerization, causing the accumulation of short actin filaments. Together with earlier studies, these results reveal that multiple L. pneumophila effectors target components of the host cytoskeleton.
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Affiliation(s)
- Zhenhua Guo
- State Key Laboratory of Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, and College of Veterinary Medicine, China Agricultural University, Beijing 100193, China; Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Robert Stephenson
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Jiazhang Qiu
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Shijun Zheng
- State Key Laboratory of Agrobiotechnology, Key Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, and College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Zhao-Qing Luo
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
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27
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Vervaet N, Kallio JP, Meier S, Salmivaara E, Eberhardt M, Zhang S, Sun X, Wu Z, Kursula P, Kursula I. Recombinant production, crystallization and preliminary structural characterization of Schistosoma japonicum profilin. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:1264-7. [PMID: 24192365 PMCID: PMC3818049 DOI: 10.1107/s174430911302647x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 09/24/2013] [Indexed: 11/11/2022]
Abstract
Helminthic parasites of the genus Schistosoma contain a tegumental membrane, which is of crucial importance for modulation of the host immune response and parasite survival. The actin cytoskeleton plays an important role in the function of the tegument. Profilins are among the most important proteins regulating actin dynamics. Schistosoma japonicum possesses one profilin-like protein, which has been characterized as a potential vaccine candidate. Notably, profilins are highly immunogenic molecules in many organisms. Here, the profilin from S. japonicum was expressed, purified and crystallized. A native data set to 1.91 Å resolution and a single-wavelength anomalous diffraction (SAD) data set to a resolution of 2.2 Å were collected. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 31.82, b = 52.17, c = 59.79 Å and a = 35.29, b = 52.15, c = 59.82 Å, respectively.
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Affiliation(s)
- Nele Vervaet
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research and German Electron Synchrotron (DESY), Notkestrasse 85, Bldg. 25b, 22607 Hamburg, Germany
| | - Juha Pekka Kallio
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research and German Electron Synchrotron (DESY), Notkestrasse 85, Bldg. 25b, 22607 Hamburg, Germany
| | - Susanne Meier
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research and German Electron Synchrotron (DESY), Notkestrasse 85, Bldg. 25b, 22607 Hamburg, Germany
| | - Emilia Salmivaara
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research and German Electron Synchrotron (DESY), Notkestrasse 85, Bldg. 25b, 22607 Hamburg, Germany
- Department of Biochemistry, University of Oulu, PO Box 3000, 90014 Oulu, Finland
| | - Maike Eberhardt
- Department of Biochemistry, University of Oulu, PO Box 3000, 90014 Oulu, Finland
| | - Shuangmin Zhang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, People’s Republic of China
| | - Xi Sun
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, People’s Republic of China
| | - Zhongdao Wu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, People’s Republic of China
| | - Petri Kursula
- Department of Biochemistry, University of Oulu, PO Box 3000, 90014 Oulu, Finland
- Biocenter Oulu, University of Oulu, PO Box 3000, 90014 Oulu, Finland
- Department of Chemistry, University of Hamburg, DESY, Notkestrasse 85, Bldg. 25b, 22607 Hamburg, Germany
| | - Inari Kursula
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research and German Electron Synchrotron (DESY), Notkestrasse 85, Bldg. 25b, 22607 Hamburg, Germany
- Department of Biochemistry, University of Oulu, PO Box 3000, 90014 Oulu, Finland
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Profilin-1 promotes the development of hypertension-induced cardiac hypertrophy. J Hypertens 2013; 31:576-86; discussion 586. [PMID: 23615214 DOI: 10.1097/hjh.0b013e32835d6a56] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Cardiac hypertrophy is a major cause of heart failure and sudden cardiac death among hypertensive individuals. The present study examined the effects of profilin-1 on hypertension-induced cardiac hypertrophy. METHODS We used adenovirus injection to knockdown or overexpress profilin-1 in spontaneous hypertensive rats (SHRs). As a control, blank adenovirus was injected into age-matched SHRs and Wistar-Kyoto rats (WKYs). SBP and cardiac mass index were measured. Cardiac tissues were stained with hematoxylin-eosin and sirius red, and cardiac ultrastructure was imaged using transmission electron microscopy. Actin filament was quantified by staining with TRIC-tagged phalloidin. Caveolin-3 abundance and endothelial nitric oxide synthase (eNOS) activity were measured using real-time quantitative PCR, Western blot or immunofluorescence staining. RESULTS Endogenous profilin-1 was highly expressed in hypertrophic myocardium of SHRs compared with WKYs. Lowering profilin-1 expression in SHRs significantly attenuated hypertension-induced cardiac hypertrophy and fibrosis and displayed a significant preservation of myofibrils, sarcolemmal caveolae, abundance of caveolin-3 protein, activity of eNOS and production of nitric oxide (NO). In contrast, transgenic overexpression of profilin-1 in SHRs induced more serious cardiac hypertrophy and fibrosis with significant reduction of sarcolemmal caveolae, caveolin-3 protein, eNOS activity, and production of NO when compared with SHR controls. CONCLUSION Profilin-1 promotes cardiac hypertrophy partly through interfering with the formation of sarcolemmal caveolae and attenuating the eNOS/NO pathway. These results demonstrate a crucial role for profilin-1 in hypertensive cardiac hypertrophy.
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Gordón-Alonso M, Rocha-Perugini V, Álvarez S, Ursa Á, Izquierdo-Useros N, Martinez-Picado J, Muñoz-Fernández MA, Sánchez-Madrid F. Actin-binding protein drebrin regulates HIV-1-triggered actin polymerization and viral infection. J Biol Chem 2013; 288:28382-97. [PMID: 23926103 DOI: 10.1074/jbc.m113.494906] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HIV-1 contact with target cells triggers F-actin rearrangements that are essential for several steps of the viral cycle. Successful HIV entry into CD4(+) T cells requires actin reorganization induced by the interaction of the cellular receptor/co-receptor complex CD4/CXCR4 with the viral envelope complex gp120/gp41 (Env). In this report, we analyze the role of the actin modulator drebrin in HIV-1 viral infection and cell to cell fusion. We show that drebrin associates with CXCR4 before and during HIV infection. Drebrin is actively recruited toward cell-virus and Env-driven cell to cell contacts. After viral internalization, drebrin clustering is retained in a fraction of the internalized particles. Through a combination of RNAi-based inhibition of endogenous drebrin and GFP-tagged expression of wild-type and mutant forms, we establish drebrin as a negative regulator of HIV entry and HIV-mediated cell fusion. Down-regulation of drebrin expression promotes HIV-1 entry, decreases F-actin polymerization, and enhances profilin local accumulation in response to HIV-1. These data underscore the negative role of drebrin in HIV infection by modulating viral entry, mainly through the control of actin cytoskeleton polymerization in response to HIV-1.
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Affiliation(s)
- Mónica Gordón-Alonso
- From the Servicio de Inmunología, Instituto de Investigación Sanitaria de la Princesa, Hospital Universitario de la Princesa, 28006 Madrid, Spain
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Lee CW, Vitriol EA, Shim S, Wise AL, Velayutham RP, Zheng JQ. Dynamic localization of G-actin during membrane protrusion in neuronal motility. Curr Biol 2013; 23:1046-56. [PMID: 23746641 PMCID: PMC3712510 DOI: 10.1016/j.cub.2013.04.057] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 04/19/2013] [Accepted: 04/19/2013] [Indexed: 11/28/2022]
Abstract
BACKGROUND Actin-based cell motility is fundamental for development, function, and malignant events in eukaryotic organisms. During neural development, axonal growth cones depend on rapid assembly and disassembly of actin filaments (F-actin) for their guided extension to specific targets for wiring. Monomeric globular actin (G-actin) is the building block for F-actin but is not considered to play a direct role in spatiotemporal control of actin dynamics in cell motility. RESULTS Here we report that a pool of G-actin dynamically localizes to the leading edge of growth cones and neuroblastoma cells to spatially elevate the G-/F-actin ratio that drives membrane protrusion and cell movement. Loss of G-actin localization leads to the cessation and retraction of membrane protrusions. Moreover, G-actin localization occurs asymmetrically in growth cones during attractive turning. Finally, we identify the actin monomer-binding proteins profilin and thymosin β4 as key molecules that localize actin monomers to the leading edge of lamellipodia for their motility. CONCLUSIONS Our results suggest that dynamic localization of G-actin provides a novel mechanism to regulate the spatiotemporal actin dynamics underlying membrane protrusion in cell locomotion and growth cone chemotaxis.
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Affiliation(s)
- Chi Wai Lee
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322
| | - Eric A. Vitriol
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322
| | - Sangwoo Shim
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322
| | - Ariel L. Wise
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322
| | - Radhi P. Velayutham
- Department of Neurosurgery, Winship Cancer Center, Emory University School of Medicine, Atlanta, GA 30322
| | - James Q. Zheng
- Departments of Cell Biology and Neurology, Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA 30322
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Domozych DS, Fujimoto C, LaRue T. Polar Expansion Dynamics in the Plant Kingdom: A Diverse and Multifunctional Journey on the Path to Pollen Tubes. PLANTS (BASEL, SWITZERLAND) 2013; 2:148-73. [PMID: 27137370 PMCID: PMC4844288 DOI: 10.3390/plants2010148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 02/24/2013] [Accepted: 03/01/2013] [Indexed: 12/18/2022]
Abstract
Polar expansion is a widespread phenomenon in plants spanning all taxonomic groups from the Charophycean Green Algae to pollen tubes in Angiosperms and Gymnosperms. Current data strongly suggests that many common features are shared amongst cells displaying polar growth mechanics including changes to the structural features of localized regions of the cell wall, mobilization of targeted secretion mechanisms, employment of the actin cytoskeleton for directing secretion and in many cases, endocytosis and coordinated interaction of multiple signal transduction mechanisms prompted by external biotic and abiotic cues. The products of polar expansion perform diverse functions including delivery of male gametes to the egg, absorption, anchorage, adhesion and photo-absorption efficacy. A comparative analysis of polar expansion dynamics is provided with special emphasis on those found in early divergent plants.
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Affiliation(s)
- David S Domozych
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, New York, NY 12866, USA.
| | - Chelsea Fujimoto
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, New York, NY 12866, USA.
| | - Therese LaRue
- Department of Biology and Skidmore Microscopy Imaging Center, Skidmore College, Saratoga Springs, New York, NY 12866, USA.
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Zhang D, Xiang J, Wang L, Xu Z, Sun L, Zhou F, Zha X, Cai D. Comparative proteomic analysis of gallbladder bile proteins related to cholesterol gallstones. PLoS One 2013; 8:e54489. [PMID: 23349907 PMCID: PMC3547929 DOI: 10.1371/journal.pone.0054489] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 12/12/2012] [Indexed: 12/11/2022] Open
Abstract
Background Nucleation of cholesterol monohydrate crystals following the aggregation and fusion of cholesterol-enriched vesicles is a critical procedure in the formation of cholesterol gallstone. Biliary proteins play important roles in the process. It is inefficient to screen pro-nucleating or anti-nucleating proteins with routine physiochemical techniques, by which we discovered several pro-nucleating proteins. Methodology/Principal Findings Based on comparative proteomic technologies, we investigated the differentially expressed proteins between the cholesterol gallstone and control groups, and between the vesicular phase and micellar phase. There are 401±75 spots detected on the cholesterol gallstone group and 389±94 spots on the control group gels, 120±24 spots detected on vesicular phase and 198±37 on micellar phase gels, and accordingly 22 and 8 differentially expressed proteins were identified successfully, respectively. Three of them, HSA, Profilin and Retinol Binding Protein, were validated by Western blot. Conclusion/Significance Some of the identified proteins are in good agreement with proteins reported to be involved in the gallstone formation before. The information from this study might provide some important clues to uncover the key proteins involved in the formation of cholesterol gallstone.
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Affiliation(s)
- Diancai Zhang
- Department of General Surgery, the First Affiliated Hospital, Nanjing Medical University, Nanjing, People’s Republic of China
| | - Jianbin Xiang
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
- Department of Surgery, Shanghai Medical College, Fudan University, Shanghai, People’s Republic of China
- * E-mail: (DC); (JBX)
| | - Liying Wang
- Key Laboratory Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, Fudan University, Shanghai, People’s Republic of China
| | - Zhibin Xu
- Key Laboratory Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, Fudan University, Shanghai, People’s Republic of China
| | - Lidong Sun
- Key Laboratory Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, Fudan University, Shanghai, People’s Republic of China
| | - Feng Zhou
- Key Laboratory Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, Fudan University, Shanghai, People’s Republic of China
| | - Xiliang Zha
- Key Laboratory Glycoconjugate Research, Ministry of Health, Department of Biochemistry and Molecular Biology, Fudan University, Shanghai, People’s Republic of China
| | - Duan Cai
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China
- Department of Surgery, Shanghai Medical College, Fudan University, Shanghai, People’s Republic of China
- * E-mail: (DC); (JBX)
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Identification of cation-binding sites on actin that drive polymerization and modulate bending stiffness. Proc Natl Acad Sci U S A 2012; 109:16923-7. [PMID: 23027950 DOI: 10.1073/pnas.1211078109] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The assembly of actin monomers into filaments and networks plays vital roles throughout eukaryotic biology, including intracellular transport, cell motility, cell division, determining cellular shape, and providing cells with mechanical strength. The regulation of actin assembly and modulation of filament mechanical properties are critical for proper actin function. It is well established that physiological salt concentrations promote actin assembly and alter the overall bending mechanics of assembled filaments and networks. However, the molecular origins of these salt-dependent effects, particularly if they involve nonspecific ionic strength effects or specific ion-binding interactions, are unknown. Here, we demonstrate that specific cation binding at two discrete sites situated between adjacent subunits along the long-pitch helix drive actin polymerization and determine the filament bending rigidity. We classify the two sites as "polymerization" and "stiffness" sites based on the effects that mutations at the sites have on salt-dependent filament assembly and bending mechanics, respectively. These results establish the existence and location of the cation-binding sites that confer salt dependence to the assembly and mechanics of actin filaments.
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Ding Z, Bae YH, Roy P. Molecular insights on context-specific role of profilin-1 in cell migration. Cell Adh Migr 2012; 6:442-9. [PMID: 23076048 DOI: 10.4161/cam.21832] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Profilin-1 (Pfn1) is a ubiquitously expressed actin-monomer binding protein that has been linked to many cellular activities ranging from control of actin polymerization to gene transcription. Traditionally, Pfn1 has been considered to be an essential control element for actin polymerization and cell migration. Seemingly contrasting this view, a few recent studies have shown evidence of an inhibitory action of Pfn1 on motility of certain types of carcinoma cells. In this review, we summarize biochemistry and functional aspects of Pfn1 in normal cells and bring in newly emerged action of Pfn1 in cancer cells that may explain its context-specific role in cell migration.
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Affiliation(s)
- Zhijie Ding
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
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Pei W, Du F, Zhang Y, He T, Ren H. Control of the actin cytoskeleton in root hair development. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 187:10-8. [PMID: 22404828 DOI: 10.1016/j.plantsci.2012.01.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 01/18/2012] [Accepted: 01/19/2012] [Indexed: 05/09/2023]
Abstract
The development of root hair includes four stages: bulge site selection, bulge formation, tip growth, and maturation. The actin cytoskeleton is involved in all of these stages and is organized into distinct arrangements in the different stages. In addition to the actin configuration, actin isoforms also play distinct roles in the different stages. The actin cytoskeleton is regulated by actin-binding proteins, such as formin, Arp2/3 complex, profilin, actin depolymerizing factor, and villin. Some upstream signals, i.e. calcium, phospholipids, and small GTPase regulate the activity of these actin-binding proteins to produce the proper actin configuration. We constructed a working model on how the actin cytoskeleton is controlled by actin-binding proteins and upstream signaling in root hair development based on the current literature: at the tip of hairs, actin polymerization appears to be facilitated by Arp2/3 complex that is activated by small GTPase, and profilin that is regulated by phosphatidylinositol 4,5-bisphosphate. Meanwhile, actin depolymerization and turnover are likely mediated by villin and actin depolymerizing factor, which are stimulated by calcium. At the shank, actin cables are produced by formin and villin. Under the complicated interaction, the actin cytoskeleton is controlled spatially and temporally during root hair development.
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Affiliation(s)
- Weike Pei
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education and College of Life Science, Beijing Normal University, Beijing 100875, China
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Zhao SH, Gao HQ, Ji X, Wang Y, Liu XJ, You BA, Cui XP, Qiu J. Effect of ouabain on myocardial ultrastructure and cytoskeleton during the development of ventricular hypertrophy. Heart Vessels 2012; 28:101-13. [PMID: 22241736 DOI: 10.1007/s00380-011-0219-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 12/08/2011] [Indexed: 02/03/2023]
Abstract
The aim of this work is to study cytoskeletal impairment during the development of ouabain-induced ventricular hypertrophy. Male Sprague-Dawley rats were treated with either ouabain or saline. Systolic blood pressure (SBP) was recorded weekly. At the end of the 3rd and 6th week, the rats were killed and cardiac mass index were measured. Hematoxylin-eosin and Sirius red staining were carried out and cardiac ultrastructure were studied using transmission electron microscopy. The mRNA level of Profilin-1, Desmin, PCNA, TGF-β(1) and ET-1 in the left ventricle were measured using real-time quantitative PCR while their protein levels were examined by Western blot or immunohistochemistry. After 3 weeks, there was no significant difference in the mean SBP, cardiac mass index, mRNA and protein expression of PCNA, TGF-β(1) and ET-1 between the two groups. However, ouabain-treated rats showed disorganized cardiac cytoskeleton with abnormal expression of Profilin-1 and Desmin. After 6 weeks, the cardiac mass index remained the same in the two groups while PCNA, TGF-β(1), and ET-1 have been upregulated in ouabain-treated rats. The cardiac cytoskeletal impairment was more severe in ouabain-treated rats with further changes of Profilin-1 and Desmin. Cytoskeletal abnormality is an ultra-early change during ouabain-induced ventricular hypertrophy, before the release of hypertrophic factors. Therapy for prevention of ouabain-induced hypertrophy should start at the early stage by preventing the cytoskeleton from disorganization.
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Affiliation(s)
- Shao-hua Zhao
- Department of Geriatric Cardiology, Qilu Hospital of Shandong University, 107 Wenhua Xi Road, Jinan, People's Republic of China
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Jégou A, Niedermayer T, Orbán J, Didry D, Lipowsky R, Carlier MF, Romet-Lemonne G. Individual actin filaments in a microfluidic flow reveal the mechanism of ATP hydrolysis and give insight into the properties of profilin. PLoS Biol 2011; 9:e1001161. [PMID: 21980262 PMCID: PMC3181223 DOI: 10.1371/journal.pbio.1001161] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 08/18/2011] [Indexed: 11/18/2022] Open
Abstract
A novel microfluidic approach allows the analysis of the dynamics of individual actin filaments, revealing both their local ADP/ADP-Pi-actin composition and that Pi release is a random mechanism. The hydrolysis of ATP associated with actin and profilin-actin polymerization is pivotal in cell motility. It is at the origin of treadmilling of actin filaments and controls their dynamics and mechanical properties, as well as their interactions with regulatory proteins. The slow release of inorganic phosphate (Pi) that follows rapid cleavage of ATP gamma phosphate is linked to an increase in the rate of filament disassembly. The mechanism of Pi release in actin filaments has remained elusive for over 20 years. Here, we developed a microfluidic setup to accurately monitor the depolymerization of individual filaments and determine their local ADP-Pi content. We demonstrate that Pi release in the filament is not a vectorial but a random process with a half-time of 102 seconds, irrespective of whether the filament is assembled from actin or profilin-actin. Pi release from the depolymerizing barbed end is faster (half-time of 0.39 seconds) and further accelerated by profilin. Profilin accelerates the depolymerization of both ADP- and ADP-Pi-F-actin. Altogether, our data show that during elongation from profilin-actin, the dissociation of profilin from the growing barbed end is not coupled to Pi release or to ATP cleavage on the terminal subunit. These results emphasize the potential of microfluidics in elucidating actin regulation at the scale of individual filaments. Actin proteins assemble into microfilaments that control cell shape and movement by polymerizing or depolymerizing. These actin monomers can bind ATP or ADP molecules. The incorporation of an ATP-actin monomer into a growing filament results in rapid cleavage of ATP into ADP and inorganic phosphate (Pi), followed by a slower release of Pi. As a consequence, actin filaments are composed mainly of ADP- and ADP-Pi-actin subunits, which have different depolymerization kinetics and mechanical properties, and can be targeted specifically by regulatory proteins that affect filament function. Hence, the understanding of many cellular processes requires a knowledge of the ADP/ADP-Pi composition of actin filaments at a molecular scale. This has so far remained elusive because traditional studies rely on measuring an average over many filaments in solution. To address this issue, we developed a microfluidics setup to monitor individual filaments with light microscopy while rapidly changing their chemical environment. We find that depolymerization accelerates progressively and corresponds to an exponential ADP-Pi-actin profile in the filament, meaning that each subunit releases its Pi with the same rate. Our method also provides novel insight into the function of profilin, a protein important for regulation of actin dynamics in cells, thus demonstrating the method's potential in the functional analysis of actin regulators.
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Affiliation(s)
- Antoine Jégou
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre de Recherche de Gif, CNRS, Gif-sur-Yvette, France
| | - Thomas Niedermayer
- Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - József Orbán
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre de Recherche de Gif, CNRS, Gif-sur-Yvette, France
| | - Dominique Didry
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre de Recherche de Gif, CNRS, Gif-sur-Yvette, France
| | - Reinhard Lipowsky
- Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Marie-France Carlier
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre de Recherche de Gif, CNRS, Gif-sur-Yvette, France
| | - Guillaume Romet-Lemonne
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre de Recherche de Gif, CNRS, Gif-sur-Yvette, France
- * E-mail:
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Husson C, Renault L, Didry D, Pantaloni D, Carlier MF. Cordon-Bleu Uses WH2 Domains as Multifunctional Dynamizers of Actin Filament Assembly. Mol Cell 2011; 43:464-77. [DOI: 10.1016/j.molcel.2011.07.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 03/18/2011] [Accepted: 07/19/2011] [Indexed: 11/26/2022]
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Gonçalves-Pimentel C, Gombos R, Mihály J, Sánchez-Soriano N, Prokop A. Dissecting regulatory networks of filopodia formation in a Drosophila growth cone model. PLoS One 2011; 6:e18340. [PMID: 21464901 PMCID: PMC3065487 DOI: 10.1371/journal.pone.0018340] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 02/25/2011] [Indexed: 11/18/2022] Open
Abstract
F-actin networks are important structural determinants of cell shape and morphogenesis. They are regulated through a number of actin-binding proteins. The function of many of these proteins is well understood, but very little is known about how they cooperate and integrate their activities in cellular contexts. Here, we have focussed on the cellular roles of actin regulators in controlling filopodial dynamics. Filopodia are needle-shaped, actin-driven cell protrusions with characteristic features that are well conserved amongst vertebrates and invertebrates. However, existing models of filopodia formation are still incomplete and controversial, pieced together from a wide range of different organisms and cell types. Therefore, we used embryonic Drosophila primary neurons as one consistent cellular model to study filopodia regulation. Our data for loss-of-function of capping proteins, enabled, different Arp2/3 complex components, the formin DAAM and profilin reveal characteristic changes in filopodia number and length, providing a promising starting point to study their functional relationships in the cellular context. Furthermore, the results are consistent with effects reported for the respective vertebrate homologues, demonstrating the conserved nature of our Drosophila model system. Using combinatorial genetics, we demonstrate that different classes of nucleators cooperate in filopodia formation. In the absence of Arp2/3 or DAAM filopodia numbers are reduced, in their combined absence filopodia are eliminated, and in genetic assays they display strong functional interactions with regard to filopodia formation. The two nucleators also genetically interact with enabled, but not with profilin. In contrast, enabled shows strong genetic interaction with profilin, although loss of profilin alone does not affect filopodia numbers. Our genetic data support a model in which Arp2/3 and DAAM cooperate in a common mechanism of filopodia formation that essentially depends on enabled, and is regulated through profilin activity at different steps.
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Affiliation(s)
- Catarina Gonçalves-Pimentel
- Wellcome Trust Centre for Cell-Matrix
Research, Faculty of Life Sciences, Manchester, United Kingdom
- Center for Neuroscience and Cell Biology,
University of Coimbra, Coimbra, Portugal
| | - Rita Gombos
- Biological Research Center, Hungarian Academy
of Sciences, Institute of Genetics, Szeged, Hungary
| | - József Mihály
- Biological Research Center, Hungarian Academy
of Sciences, Institute of Genetics, Szeged, Hungary
| | - Natalia Sánchez-Soriano
- Wellcome Trust Centre for Cell-Matrix
Research, Faculty of Life Sciences, Manchester, United Kingdom
| | - Andreas Prokop
- Wellcome Trust Centre for Cell-Matrix
Research, Faculty of Life Sciences, Manchester, United Kingdom
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Bednarek ML, Speich JE, Miner AS, Ratz PH. Active tension adaptation at a shortened arterial muscle length: inhibition by cytochalasin-D. Am J Physiol Heart Circ Physiol 2011; 300:H1166-73. [PMID: 21239639 DOI: 10.1152/ajpheart.00009.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Unlike the static length-tension curve of striated muscle, airway and urinary bladder smooth muscles display a dynamic length-tension curve. Much less is known about the plasticity of the length-tension curve of vascular smooth muscle. The present study demonstrates that there were significant increases of ∼15% in the phasic phase and ∼10% in the tonic phase of a third KCl-induced contraction of a rabbit femoral artery ring relative to the first contraction after a 20% decrease in length from an optimal muscle length (L(0)) to 0.8-fold L(0). Typically, three repeated contractions were necessary for full length adaptation to occur. The tonic phase of a third KCl-induced contraction was increased by ∼50% after the release of tissues from 1.25-fold to 0.75-fold L(o). The mechanism for this phenomenon did not appear to lie in thick filament regulation because there was no increase in myosin light chain (MLC) phosphorylation to support the increase in tension nor was length adaptation abolished when Ca(2+) entry was limited by nifedipine and when Rho kinase (ROCK) was blocked by H-1152. However, length adaptation of both the phasic and tonic phases was abolished when actin polymerization was inhibited through blockade of the plus end of actin by cytochalasin-D. Interestingly, inhibition of actin polymerization when G-actin monomers were sequestered by latrunculin-B increased the phasic phase and had no effect on the tonic phase of contraction during length adaptation. These data suggest that for a given level of cytosolic free Ca(2+), active tension in the femoral artery can be sensitized not only by regulation of MLC phosphatase via ROCK and protein kinase C, as has been reported by others, but also by a nonmyosin regulatory mechanism involving actin polymerization. Dysregulation of this form of active tension modulation may provide insight into alterations of large artery stiffness in hypertension.
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Affiliation(s)
- Melissa L Bednarek
- Departments of Physiology, School of Engineering, Virginia Commonwealth University, Richmond, 23298-0614, USA.
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Abstract
Cell migration is a fundamental process that controls morphogenesis and inflammation. Its deregulation causes or is part of many diseases, including autoimmune syndromes, chronic inflammation, mental retardation, and cancer. Cell migration is an integral part of the cell biology, embryology, immunology, and neuroscience fields; as such, it has benefited from quantum leaps in molecular biology, biochemistry, and imaging techniques, and the emergence of the genomic and proteomic era. Combinations of these techniques have revealed new and exciting insights that explain how cells adhere and move, how the migration of multiple cells are coordinated and regulated, and how the cells interact with neighboring cells and/or react to changes in their microenvironment. This introduction provides a primer of the molecular and cellular insights, particularly the signaling networks, which control the migration of individual cells as well as collective migrations. The rest of the chapters are devoted to describe in detail some of the most salient technical advances that have illuminated the field of cell migration in recent years.
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Sun X, Kovacs T, Hu YJ, Yang WX. The role of actin and myosin during spermatogenesis. Mol Biol Rep 2010; 38:3993-4001. [DOI: 10.1007/s11033-010-0517-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2010] [Accepted: 11/13/2010] [Indexed: 01/08/2023]
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Caglayan E, Romeo GR, Kappert K, Odenthal M, Südkamp M, Body SC, Shernan SK, Hackbusch D, Vantler M, Kazlauskas A, Rosenkranz S. Profilin-1 is expressed in human atherosclerotic plaques and induces atherogenic effects on vascular smooth muscle cells. PLoS One 2010; 5:e13608. [PMID: 21049052 PMCID: PMC2963617 DOI: 10.1371/journal.pone.0013608] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Accepted: 09/13/2010] [Indexed: 01/29/2023] Open
Abstract
Background Profilin-1 is an ubiquitous actin binding protein. Under pathological conditions such as diabetes, profilin-1 levels are increased in the vascular endothelium. We recently demonstrated that profilin-1 overexpression triggers indicators of endothelial dysfunction downstream of LDL signaling, and that attenuated expression of profilin-1 confers protection from atherosclerosis in vivo. Methodology Here we monitored profilin-1 expression in human atherosclerotic plaques by immunofluorescent staining. The effects of recombinant profilin-1 on atherogenic signaling pathways and cellular responses such as DNA synthesis (BrdU-incorporation) and chemotaxis (modified Boyden-chamber) were evaluated in cultured rat aortic and human coronary vascular smooth muscle cells (VSMCs). Furthermore, the correlation between profilin-1 serum levels and the degree of atherosclerosis was assessed in humans. Principal Findings In coronary arteries from patients with coronary heart disease, we found markedly enhanced profilin expression in atherosclerotic plaques compared to the normal vessel wall. Stimulation of rat aortic and human coronary VSMCs with recombinant profilin-1 (10−6 M) in vitro led to activation of intracellular signaling cascades such as phosphorylation of Erk1/2, p70S6 kinase and PI3K/Akt within 10 minutes. Furthermore, profilin-1 concentration-dependently induced DNA-synthesis and migration of both rat and human VSMCs, respectively. Inhibition of PI3K (Wortmannin, LY294002) or Src-family kinases (SU6656, PP2), but not PLCγ (U73122), completely abolished profilin-induced cell cycle progression, whereas PI3K inhibition partially reduced the chemotactic response. Finally, we found that profilin-1 serum levels were significantly elevated in patients with severe atherosclerosis in humans (p<0.001 vs. no atherosclerosis or control group). Conclusions Profilin-1 expression is significantly enhanced in human atherosclerotic plaques compared to the normal vessel wall, and the serum levels of profilin-1 correlate with the degree of atherosclerosis in humans. The atherogenic effects exerted by profilin-1 on VSMCs suggest an auto-/paracrine role within the plaque. These data indicate that profilin-1 might critically contribute to atherogenesis and may represent a novel therapeutic target.
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Affiliation(s)
- Evren Caglayan
- Klinik III für Innere Medizin, Universität zu Köln, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Universität zu Köln, Cologne, Germany
| | - Giulio R. Romeo
- Department of Cellular and Molecular Physiology, Joslin Diabetes Center, Boston, Massachusetts, United States of America
| | - Kai Kappert
- Institut für Pharmakologie, Center for Cardiovascular Research (CCR), Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - Michael Südkamp
- Herz- und Gefäßchirurgie, Universitätsklinikum Freiburg, Freiburg, Germany
| | - Simon C. Body
- Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Stanton K. Shernan
- Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Daniel Hackbusch
- Institut für Pharmakologie, Center for Cardiovascular Research (CCR), Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Marius Vantler
- Klinik III für Innere Medizin, Universität zu Köln, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Universität zu Köln, Cologne, Germany
| | - Andrius Kazlauskas
- Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Stephan Rosenkranz
- Klinik III für Innere Medizin, Universität zu Köln, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Universität zu Köln, Cologne, Germany
- * E-mail:
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Defining a core set of actin cytoskeletal proteins critical for actin-based motility of Rickettsia. Cell Host Microbe 2010; 7:388-98. [PMID: 20478540 DOI: 10.1016/j.chom.2010.04.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 03/09/2010] [Accepted: 03/25/2010] [Indexed: 01/15/2023]
Abstract
Many Rickettsia species are intracellular bacterial pathogens that use actin-based motility for spread during infection. However, while other bacteria assemble actin tails consisting of branched networks, Rickettsia assemble long parallel actin bundles, suggesting the use of a distinct mechanism for exploiting actin. To identify the underlying mechanisms and host factors involved in Rickettsia parkeri actin-based motility, we performed an RNAi screen targeting 115 actin cytoskeletal genes in Drosophila cells. The screen delineated a set of four core proteins-profilin, fimbrin/T-plastin, capping protein, and cofilin--as crucial for determining actin tail length, organizing filament architecture, and enabling motility. In mammalian cells, these proteins were localized throughout R. parkeri tails, consistent with a role in motility. Profilin and fimbrin/T-plastin were critical for the motility of R. parkeri but not Listeria monocytogenes. Our results highlight key distinctions between the evolutionary strategies and molecular mechanisms employed by bacterial pathogens to assemble and organize actin.
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Wang J, Wang HY, Zhao PM, Han LB, Jiao GL, Zheng YY, Huang SJ, Xia GX. Overexpression of a profilin (GhPFN2) promotes the progression of developmental phases in cotton fibers. PLANT & CELL PHYSIOLOGY 2010; 51:1276-90. [PMID: 20558432 DOI: 10.1093/pcp/pcq086] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Cotton fiber development at the stages of elongation and secondary wall synthesis determines the traits of fiber length and strength. To date, the mechanisms controlling the progression of these two phases remain elusive. In this work, the function of a fiber-preferential actin-binding protein (GhPFN2) was characterized by cytological and molecular studies on the fibers of transgenic green-colored cotton (Gossypium hirsutum) through three successive generations. Overexpression of GhPFN2 caused pre-terminated cell elongation, resulting in a marked decrease in the length of mature fibers. Cytoskeleton staining and quantitative assay revealed that thicker and more abundant F-actin bundles formed during the elongation stage in GhPFN2-overexpressing fibers. Accompanying this alteration, the developmental reorientation of transverse microtubules to the oblique direction was advanced by 2 d at the period of transition from elongation to secondary wall deposition. Birefringence and reverse transcription-PCR analyses showed that earlier onset of secondary wall synthesis occurred in parallel. These data demonstrate that formation of the higher actin structure plays a determinant role in the progression of developmental phases in cotton fibers, and that GhPFN2 acts as a critical modulator in this process. Such a function of the actin cytoskeleton in cell phase conversion may be common to other secondary wall-containing plant cells.
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Affiliation(s)
- Juan Wang
- Institute of Microbiology, Chinese Academy of Sciences, Beijing, PR China
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Borro M, Gentile G, De Luca O, Torre MS, Aimati L, Tatarelli C, Antonietta Aloe Spiriti M, Christina Cox M, Simmaco M. Specific effects exerted by B-lymphoproliferative diseases on peripheral T-lymphocyte protein expression. Br J Haematol 2010; 150:463-72. [PMID: 20618332 DOI: 10.1111/j.1365-2141.2010.08285.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A proteomic approach was applied to study the protein expression profile of peripheral T-cells derived from patients at the onset of different B-lymphoproliferative diseases, because a rising interest in specific actions played by T-cells in such pathologies has emerged. Decreased levels of profilin-1 and cofilin-1 and increased levels of coronin1A and prohibitin were found in patients, compared with healthy controls. The protein-protein interaction network of these proteins was studied using a web-based bioinformatics tool, highlighting the actin cytoskeleton regulation as the main biological process involved in peripheral T-cells of such patients. Unsupervised cluster analysis of protein expression data shows that the recorded alteration of T-cell proteome was specifically induced by B-cell pathologies.
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Affiliation(s)
- Marina Borro
- 2nd Faculty of Medicine, Sant'Andrea Hospital, Sapienza University of Rome, Italy
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Yarmola EG, Bubb MR. How depolymerization can promote polymerization: the case of actin and profilin. Bioessays 2010; 31:1150-60. [PMID: 19795407 DOI: 10.1002/bies.200900049] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Rapid polymerization and depolymerization of actin filaments in response to extracellular stimuli is required for normal cell motility and development. Profilin is one of the most important actin-binding proteins; it regulates actin polymerization and interacts with many cytoskeletal proteins that link actin to extracellular membrane. The molecular mechanism of profilin has been extensively considered and debated in the literature for over two decades. Here we discuss several accepted hypotheses regarding the mechanism of profilin function as well as new recently emerged possibilities. Thermal noise is routine in molecular world and unsurprisingly, nature has found a way to utilize it. An increasing amount of theoretical and experimental research suggests that fluctuation-based processes play important roles in many cell events. Here we show how a fluctuation-based process of exchange diffusion is involved in the regulation of actin polymerization.
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Affiliation(s)
- Elena G Yarmola
- Department of Medicine, University of Florida, Gainesville, FL 32610, USA.
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Usual and unusual biochemical properties of ADF/cofilin-like protein Adf73p in ciliate Tetrahymena thermophila. Biochem Biophys Res Commun 2009; 390:54-9. [DOI: 10.1016/j.bbrc.2009.09.063] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 09/16/2009] [Indexed: 11/19/2022]
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Mutational analysis reveals a noncontractile but interactive role of actin and profilin in viral RNA-dependent RNA synthesis. J Virol 2009; 83:10869-76. [PMID: 19710142 DOI: 10.1128/jvi.01271-09] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
As obligatory parasites, viruses co-opt a variety of cellular functions for robust replication. The expression of the nonsegmented negative-strand RNA genome of respiratory syncytial virus (RSV), a significant pediatric pathogen, absolutely requires actin and is stimulated by the actin-regulatory protein profilin. As actin is a major contractile protein, it was important to determine whether the known functional domains of actin and profilin were important for their ability to activate RSV transcription. Analyses of recombinant mutants in a reconstituted RSV transcription system suggested that the divalent-cation-binding domain of actin is critically needed for binding to the RSV genome template and for the activation of viral RNA synthesis. In contrast, the nucleotide-binding domain and the N-terminal acidic domain were needed neither for template binding nor for transcription. Specific surface residues of actin, required for actin-actin contact during filamentation, were also nonessential for viral transcription. Unlike actin, profilin did not directly bind to the viral template but was recruited by actin. Mutation of the interactive residues of actin or profilin, resulting in the loss of actin-profilin binding, also abolished profilin's ability to stimulate viral transcription. Together, these results suggest that actin acts as a classical transcription factor for the virus by divalent-cation-dependent binding to the viral template and that profilin acts as a transcriptional cofactor, in part by associating with actin. This essential viral role of actin is independent of its contractile cellular role.
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50
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Gieni RS, Hendzel MJ. Actin dynamics and functions in the interphase nucleus: moving toward an understanding of nuclear polymeric actin. Biochem Cell Biol 2009; 87:283-306. [PMID: 19234542 DOI: 10.1139/o08-133] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Actin exists as a dynamic equilibrium of monomers and polymers within the nucleus of living cells. It is utilized by the cell for many aspects of gene regulation, including mRNA processing, chromatin remodelling, and global gene expression. Polymeric actin is now specifically linked to transcription by RNA polymerase I, II, and III. An active process, requiring both actin polymers and myosin, appears to drive RNA polymerase I transcription, and is also implicated in long-range chromatin movement. This type of mechanism brings activated genes from separate chromosomal territories together, and then participates in their compartmentalization near nuclear speckles. Nuclear speckle formation requires polymeric actin, and factors promoting polymerization, such as profilin and PIP2, are concentrated there. A review of the literature shows that a functional population of G-actin cycles between the cytoplasm and the nucleoplasm. Its nuclear concentration is dependent on the cytoplasmic G-actin pool, as well as on the activity of import and export mechanisms and the availability of interactions that sequester it within the nucleus. The N-WASP-Arp2/3 actin polymer-nucleating mechanism functions in the nucleus, and its mediators, including NCK, PIP2, and Rac1, can be found in the nucleoplasm, where they likely influence the kinetics of polymer formation. The actin polymer species produced are tightly regulated, and may take on conformations not easily recognized by phalloidin. Many of the factors that cleave F-actin in the cytoplasm are present at high levels in the nucleoplasm, and are also likely to affect actin dynamics there. The absolute and relative G-actin content in the nucleoplasm and the cytoplasm of a cell contains information about the homeostatic state of that cell. We propose that the cycling of G-actin between the nucleus and cytoplasm represents a signal transduction mechanism that can function through both extremes of global cellular G-actin content. MAL signalling within the serum response factor pathway, when G-actin levels are low, represents a well-studied example of actin functioning in signal transduction. The translocation of NCK into the nucleus, along with G-actin, during dissolution of the cytoskeleton in response to DNA damage represents another instance of a unique signalling mechanism operating when G-actin levels are high.
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Affiliation(s)
- Randall S Gieni
- Cross Cancer Institute and Department of Oncology, Faculty of Medicine, University of Alberta, Edmonton, ABT6G1Z2, Canada
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