1
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Sun Z, Liu J, Chen Y, Zhang J, Zhong G. RNAi-mediated knockdown of α-Spectrin depresses reproductive performance in female Bactrocera dorsalis. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 196:105611. [PMID: 37945250 DOI: 10.1016/j.pestbp.2023.105611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 08/30/2023] [Accepted: 09/01/2023] [Indexed: 11/12/2023]
Abstract
The female reproductive potential plays a crucial role in reproduction, population dynamics and population maintenance. However, the function of endogenous genes in undifferentiated germ cells has been largely unknown in Bactrocera dorsalis. In this study, the conservative analysis showed that α-Spectrin shared a similarity in B. dorsalis and other dipteral flies. Further, the differential expression of α-Spectrin was examined in B. dorsalis by RT-qPCR, and the expression pattern of α-Spectrin protein was identified in female adult ovaries by using immunostaining. During the development of ovary, the change on the number of undifferentiated germ cells was also characterized and analyzed. To understand the function of α-Spectrin in B. dorsalis ovary, the RNAi-based knockdown was conducted, and the RNAi efficiency was examined by RT-qPCR, western blot and bioassay. The results revealed that the α-Spectrin dsRNA could strikingly decrease the expression level of α-Spectrin in ovaries and diminish oviposition and ovary size as a consequence of downregulation of α-Spectrin. Overall, our study facilitates reproductive research on the function of conservative genes in B. dorsalis ovary, which may provide a new insight into seeking novel target genes for pest management control.
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Affiliation(s)
- Zhipeng Sun
- National Key Laboratory of Green Pesticide, PR China; Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture and Rural Affairs, PR China; Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, PR China.
| | - Jin Liu
- National Key Laboratory of Green Pesticide, PR China; Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture and Rural Affairs, PR China; Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, PR China.
| | - Yaoyao Chen
- National Key Laboratory of Green Pesticide, PR China; Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture and Rural Affairs, PR China; Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, PR China.
| | - Jing Zhang
- National Key Laboratory of Green Pesticide, PR China; Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture and Rural Affairs, PR China; Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, PR China.
| | - Guohua Zhong
- National Key Laboratory of Green Pesticide, PR China; Key Laboratory of Crop Integrated Pest Management in South China, Ministry of Agriculture and Rural Affairs, PR China; Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, PR China.
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2
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Park SE, Kim JC, Im Y, Kim JS. Pathogenesis and defense mechanism while Beauveria bassiana JEF-410 infects poultry red mite, Dermanyssus gallinae. PLoS One 2023; 18:e0280410. [PMID: 36800366 PMCID: PMC9937463 DOI: 10.1371/journal.pone.0280410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 12/28/2022] [Indexed: 02/18/2023] Open
Abstract
The poultry red mite, Dermanyssus gallinae (Mesostigmata: Dermanyssidae), is a major pest that causes great damage to chicken egg production. In one of our previous studies, the management of red mites using entomopathogenic fungi was evaluated, and the acaricidal fungus Beauveria bassiana JEF-410 was selected for further research. In this study, we tried to elucidate the pathogenesis of B. bassiana JEF-410 and the defense mechanisms of red mites at a transcriptome level. Red mites collected from a chicken farm were treated with B. bassiana JEF-410. When the mortality of infected red mites reached 50%, transcriptome analyses were performed to determine the interaction between B. bassiana JEF-410 and red mites. Uninfected red mites and non-infecting fungus served as controls. In B. bassiana JEF-410, up-regulated gene expression was observed in tryptophan metabolism and secondary metabolite biosynthesis pathways. Genes related to acetyl-CoA synthesis were up-regulated in tryptophan metabolism, suggesting that energy metabolism and stress management were strongly activated. Secondary metabolites associated with fungal up-regulated DEGs were related to the production of substances toxic to insects such as beauvericin and beauveriolide, efflux pump of metabolites, energy production, and resistance to stress. In red mites, physical and immune responses that strengthen the cuticle against fungal infection were highly up-regulated. From these gene expression analyses, we identified essential factors for fungal infection and subsequent defenses of red mites. These results will serve as a strong platform for explaining the interaction between B. bassiana JEF-410 and red mites in the stage of active infection.
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Affiliation(s)
- So Eun Park
- Department of Agricultural Biology, College of Agriculture & Life Sciences, Jeonbuk National University, Jeonju, Korea
| | - Jong-Cheol Kim
- Department of Agricultural Biology, College of Agriculture & Life Sciences, Jeonbuk National University, Jeonju, Korea
| | - Yeram Im
- Department of Agricultural Biology, College of Agriculture & Life Sciences, Jeonbuk National University, Jeonju, Korea
| | - Jae Su Kim
- Department of Agricultural Biology, College of Agriculture & Life Sciences, Jeonbuk National University, Jeonju, Korea
- Department of Agricultural Convergence Technology, Jeonbuk National University, Jeonju, Korea
- * E-mail:
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3
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Li D. Role of Spectrin in Endocytosis. Cells 2022; 11:cells11152459. [PMID: 35954302 PMCID: PMC9368487 DOI: 10.3390/cells11152459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/02/2022] [Accepted: 08/06/2022] [Indexed: 11/16/2022] Open
Abstract
Cytoskeletal spectrin is found in (non)erythroid cells. Eukaryotic endocytosis takes place for internalizing cargos from extracellular milieu. The role of spectrin in endocytosis still remains poorly understood. Here, I summarize current knowledge of spectrin function, spectrin-based cytoskeleton and endocytosis of erythrocytes, and highlight how spectrin contributes to endocytosis and working models in different types of cells. From an evolutionary viewpoint, I discuss spectrin and endocytosis in a range of organisms, particularly in plants and yeast where spectrin is absent. Together, the role of spectrin in endocytosis is related to its post-translational modification, movement/rearrangement, elimination (by proteases) and meshwork fencing.
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Affiliation(s)
- Donghai Li
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, China
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4
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The basement membrane controls size and integrity of the Drosophila tracheal tubes. Cell Rep 2022; 39:110734. [PMID: 35476979 DOI: 10.1016/j.celrep.2022.110734] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 01/17/2022] [Accepted: 04/04/2022] [Indexed: 11/20/2022] Open
Abstract
Biological tubes are fundamental units of most metazoan organs. Their defective morphogenesis can cause malformations and pathologies. An integral component of biological tubes is the extracellular matrix, present apically (aECM) and basally (BM). Studies using the Drosophila tracheal system established an essential function for the aECM in tubulogenesis. Here, we demonstrate that the BM also plays a critical role in this process. We find that BM components are deposited in a spatial-temporal manner in the trachea. We show that laminins, core BM components, control size and shape of tracheal tubes and their topology within the embryo. At a cellular level, laminins control cell shape changes and distribution of the cortical cytoskeleton component α-spectrin. Finally, we report that the BM and aECM act independently-yet cooperatively-to control tube elongation and together to guarantee tissue integrity. Our results unravel key roles for the BM in shaping, positioning, and maintaining biological tubes.
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5
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King TR, Kramer J, Cheng YS, Swope D, Kramer SG. Enabled/VASP is required to mediate proper sealing of opposing cardioblasts during Drosophila dorsal vessel formation. Dev Dyn 2021; 250:1173-1190. [PMID: 33587326 DOI: 10.1002/dvdy.317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 01/16/2021] [Accepted: 02/02/2021] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION The Drosophila dorsal vessel (DV) is comprised of two opposing rows of cardioblasts (CBs) that migrate toward the dorsal midline during development. While approaching the midline, CBs change shape, enabling dorsal and ventral attachments with their contralateral partners to create a linear tube with a central lumen. We previously demonstrated DV closure occurs via a "buttoning" mechanism where specific CBs advance ahead of their lateral neighbors, and attach creating transient holes, which eventually seal. RESULTS Here, we investigate the role of the actin-regulatory protein enabled (Ena) in DV closure. Loss of Ena results in DV cell shape and alignment defects. Live analysis of DV formation in ena mutants shows a reduction in CB leading edge protrusion length and gaps in the DV between contralateral CB pairs. These gaps occur primarily between a specific genetic subtype of CBs, which express the transcription factor seven-up (Svp) and form the ostia inflow tracts of the heart. In WT embryos these gaps between Svp+ CBs are observed transiently during the final stages of DV closure. CONCLUSIONS Our data suggest that Ena modulates the actin cytoskeleton in order to facilitate the complete sealing of the DV during the final stages of cardiac tube formation.
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Affiliation(s)
- Tiffany R King
- Graduate Program in Cell and Developmental Biology, Rutgers Graduate School of Biomedical Sciences at Robert Wood Johnson Medical School, Department of Pathology and Laboratory Medicine, Piscataway, New Jersey, USA.,Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Joseph Kramer
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Yi-Shan Cheng
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - David Swope
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA.,Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, New Jersey, USA
| | - Sunita G Kramer
- Department of Pathology and Laboratory Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
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6
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Van de Vondel L, Baets J, Beijer D. Reply: De novo SPTAN1 mutation in axonal sensorimotor neuropathy and developmental disorder. Brain 2021; 143:e105. [PMID: 33207363 DOI: 10.1093/brain/awaa345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Liedewei Van de Vondel
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
| | - Jonathan Baets
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Belgium
| | - Danique Beijer
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
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7
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Deng H, Yang L, Wen P, Lei H, Blount P, Pan D. Spectrin couples cell shape, cortical tension, and Hippo signaling in retinal epithelial morphogenesis. J Cell Biol 2020; 219:133846. [PMID: 32328630 PMCID: PMC7147103 DOI: 10.1083/jcb.201907018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 11/26/2019] [Accepted: 01/17/2020] [Indexed: 01/05/2023] Open
Abstract
Although extracellular force has a profound effect on cell shape, cytoskeleton tension, and cell proliferation through the Hippo signaling effector Yki/YAP/TAZ, how intracellular force regulates these processes remains poorly understood. Here, we report an essential role for spectrin in specifying cell shape by transmitting intracellular actomyosin force to cell membrane. While activation of myosin II in Drosophila melanogaster pupal retina leads to increased cortical tension, apical constriction, and Yki-mediated hyperplasia, spectrin mutant cells, despite showing myosin II activation and Yki-mediated hyperplasia, paradoxically display decreased cortical tension and expanded apical area. Mechanistically, we show that spectrin is required for tethering cortical F-actin to cell membrane domains outside the adherens junctions (AJs). Thus, in the absence of spectrin, the weakened attachment of cortical F-actin to plasma membrane results in a failure to transmit actomyosin force to cell membrane, causing an expansion of apical surfaces. These results uncover an essential mechanism that couples cell shape, cortical tension, and Hippo signaling and highlight the importance of non–AJ membrane domains in dictating cell shape in tissue morphogenesis.
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Affiliation(s)
- Hua Deng
- Department of Physiology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Limin Yang
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Pei Wen
- Department of Physiology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Huiyan Lei
- Department of Physiology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX
| | - Paul Blount
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Duojia Pan
- Department of Physiology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX
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8
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Beijer D, Deconinck T, De Bleecker JL, Dotti MT, Malandrini A, Urtizberea JA, Zulaica M, López de Munain A, Asselbergh B, De Jonghe P, Baets J. Nonsense mutations in alpha-II spectrin in three families with juvenile onset hereditary motor neuropathy. Brain 2020; 142:2605-2616. [PMID: 31332438 DOI: 10.1093/brain/awz216] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 04/25/2019] [Accepted: 05/28/2019] [Indexed: 01/09/2023] Open
Abstract
Distal hereditary motor neuropathies are a rare subgroup of inherited peripheral neuropathies hallmarked by a length-dependent axonal degeneration of lower motor neurons without significant involvement of sensory neurons. We identified patients with heterozygous nonsense mutations in the αII-spectrin gene, SPTAN1, in three separate dominant hereditary motor neuropathy families via next-generation sequencing. Variable penetrance was noted for these mutations in two of three families, and phenotype severity differs greatly between patients. The mutant mRNA containing nonsense mutations is broken down by nonsense-mediated decay and leads to reduced protein levels in patient cells. Previously, dominant-negative αII-spectrin gene mutations were described as causal in a spectrum of epilepsy phenotypes.
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Affiliation(s)
- Danique Beijer
- Neurogenetics Group, Center for Molecular Neurology, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
| | - Tine Deconinck
- Neurogenetics Group, Center for Molecular Neurology, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
| | | | - Maria Teresa Dotti
- Department of Medicine, Surgery and Neuroscience, University of Siena, Italy
| | | | | | - Miren Zulaica
- Neuroscience Area, Institute Biodonostia, Hospital Universitario Donostia, San Sebastian, Spain.,Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Institute Carlos III, Madrid, Spain
| | - Adolfo López de Munain
- Neuroscience Area, Institute Biodonostia, Hospital Universitario Donostia, San Sebastian, Spain.,Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Institute Carlos III, Madrid, Spain
| | - Bob Asselbergh
- VIB-UAntwerp Center for Molecular Neurology, University of Antwerp, Antwerp, Belgium
| | - Peter De Jonghe
- Neurogenetics Group, Center for Molecular Neurology, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Belgium
| | - Jonathan Baets
- Neurogenetics Group, Center for Molecular Neurology, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Belgium
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9
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Lambert MW. The functional importance of lamins, actin, myosin, spectrin and the LINC complex in DNA repair. Exp Biol Med (Maywood) 2019; 244:1382-1406. [PMID: 31581813 PMCID: PMC6880146 DOI: 10.1177/1535370219876651] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Three major proteins in the nucleoskeleton, lamins, actin, and spectrin, play essential roles in maintenance of nuclear architecture and the integrity of the nuclear envelope, in mechanotransduction and mechanical coupling between the nucleoskeleton and cytoskeleton, and in nuclear functions such as regulation of gene expression, transcription and DNA replication. Less well known, but critically important, are the role these proteins play in DNA repair. The A-type and B-type lamins, nuclear actin and myosin, spectrin and the LINC (linker of nucleoskeleton and cytoskeleton) complex each function in repair of DNA damage utilizing various repair pathways. The lamins play a role in repair of DNA double-strand breaks (DSBs) by nonhomologous end joining (NHEJ) or homologous recombination (HR). Actin is involved in repair of DNA DSBs and interacts with myosin in facilitating relocalization of these DSBs in heterochromatin for HR repair. Nonerythroid alpha spectrin (αSpII) plays a critical role in repair of DNA interstrand cross-links (ICLs) where it acts as a scaffold in recruitment of repair proteins to sites of damage and is important in the initial damage recognition and incision steps of the repair process. The LINC complex contributes to the repair of DNA DSBs and ICLs. This review will address the important functions of these proteins in the DNA repair process, their mechanism of action, and the profound impact a defect or deficiency in these proteins has on cellular function. The critical roles of these proteins in DNA repair will be further emphasized by discussing the human disorders and the pathophysiological changes that result from or are related to deficiencies in these proteins. The demonstrated function for each of these proteins in the DNA repair process clearly indicates that there is another level of complexity that must be considered when mechanistically examining factors crucial for DNA repair.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology, Immunology and Laboratory
Medicine, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
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10
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The Role of Nonerythroid Spectrin αII in Cancer. JOURNAL OF ONCOLOGY 2019; 2019:7079604. [PMID: 31186638 PMCID: PMC6521328 DOI: 10.1155/2019/7079604] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 04/05/2019] [Accepted: 04/09/2019] [Indexed: 12/18/2022]
Abstract
Nonerythroid spectrin αII (SPTAN1) is an important cytoskeletal protein that ensures vital cellular properties including polarity and cell stabilization. In addition, it is involved in cell adhesion, cell-cell contact, and apoptosis. The detection of altered expression of SPTAN1 in tumors indicates that SPTAN1 might be involved in the development and progression of cancer. SPTAN1 has been described in cancer and therapy response and proposed as a potential marker protein for neoplasia, tumor aggressiveness, and therapeutic efficiency. On one hand, the existing data suggest that overexpression of SPTAN1 in tumor cells reflects neoplastic and tumor promoting activity. On the other hand, nuclear SPTAN1 can have tumor suppressing effects by enabling DNA repair through interaction with DNA repair proteins. Moreover, SPTAN1 cleavage products occur during apoptosis and could serve as markers for the efficacy of cancer therapy. Due to SPTAN1's multifaceted functions and its role in adhesion and migration, SPTAN1 can influence tumor growth and progression in both positive and negative directions depending on its specific regulation. This review summarizes the current knowledge on SPTAN1 in cancer and depicts several mechanisms by which SPTAN1 could impact tumor development and aggressiveness.
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11
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Downregulation of SPTAN1 is related to MLH1 deficiency and metastasis in colorectal cancer. PLoS One 2019; 14:e0213411. [PMID: 30856214 PMCID: PMC6411122 DOI: 10.1371/journal.pone.0213411] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 02/20/2019] [Indexed: 01/02/2023] Open
Abstract
Introduction Colorectal cancers (CRCs) deficient in the DNA mismatch repair protein MutL homolog 1 (MLH1) display distinct clinicopathological features and require a different therapeutic approach compared to CRCs with MLH1 proficiency. However, the molecular basis of this fundamental difference remains elusive. Here, we report that MLH1-deficient CRCs exhibit reduced levels of the cytoskeletal scaffolding protein non-erythroid spectrin αII (SPTAN1), and that tumor progression and metastasis of CRCs correlate with SPTAN1 levels. Methods and results To investigate the link between MLH1 and SPTAN1 in cancer progression, a cohort of 189 patients with CRC was analyzed by immunohistochemistry. Compared with the surrounding normal mucosa, SPTAN1 expression was reduced in MLH1-deficient CRCs, whereas MLH1-proficient CRCs showed a significant upregulation of SPTAN1. Overall, we identified a strong correlation between MLH1 status and SPTAN1 expression. When comparing TNM classification and SPTAN1 levels, we found higher SPTAN1 levels in stage I CRCs, while stages II to IV showed a gradual reduction of SPTAN1 expression. In addition, SPTAN1 expression was lower in metastatic compared with non-metastatic CRCs. Knockdown of SPTAN1 in CRC cell lines demonstrated decreased cell viability, impaired cellular mobility and reduced cell-cell contact formation, indicating that SPTAN1 plays an important role in cell growth and cell attachment. The observed weakened cell-cell contact of SPTAN1 knockdown cells might indicate that tumor cells expressing low levels of SPTAN1 detach from their primary tumor and metastasize more easily. Conclusion Taken together, we demonstrate that MLH1 deficiency, low SPTAN1 expression, and tumor progression and metastasis are in close relation. We conclude that SPTAN1 is a candidate molecule explaining the tumor progression and metastasis of MLH1-deficient CRCs. The detailed analysis of SPTAN1 is now mandatory to substantiate its relevance and its potential value as a candidate protein for targeted therapy, and as a predictive marker of cancer aggressiveness.
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12
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Lambert MW. Spectrin and its interacting partners in nuclear structure and function. Exp Biol Med (Maywood) 2019; 243:507-524. [PMID: 29557213 DOI: 10.1177/1535370218763563] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nonerythroid αII-spectrin is a structural protein whose roles in the nucleus have just begun to be explored. αII-spectrin is an important component of the nucleoskelelton and has both structural and non-structural functions. Its best known role is in repair of DNA ICLs both in genomic and telomeric DNA. αII-spectrin aids in the recruitment of repair proteins to sites of damage and a proposed mechanism of action is presented. It interacts with a number of different groups of proteins in the nucleus, indicating it has roles in additional cellular functions. αII-spectrin, in its structural role, associates/co-purifies with proteins important in maintaining the architecture and mechanical properties of the nucleus such as lamin, emerin, actin, protein 4.1, nuclear myosin, and SUN proteins. It is important for the resilience and elasticity of the nucleus. Thus, αII-spectrin's role in cellular functions is complex due to its structural as well as non-structural roles and understanding the consequences of a loss or deficiency of αII-spectrin in the nucleus is a significant challenge. In the bone marrow failure disorder, Fanconi anemia, there is a deficiency in αII-spectrin and, among other characteristics, there is defective DNA repair, chromosome instability, and congenital abnormalities. One may speculate that a deficiency in αII-spectrin plays an important role not only in the DNA repair defect but also in the congenital anomalies observed in Fanconi anemia , particularly since αII-spectrin has been shown to be important in embryonic development in a mouse model. The dual roles of αII-spectrin in the nucleus in both structural and non-structural functions make this an extremely important protein which needs to be investigated further. Such investigations should help unravel the complexities of αII-spectrin's interactions with other nuclear proteins and enhance our understanding of the pathogenesis of disorders, such as Fanconi anemia , in which there is a deficiency in αII-spectrin. Impact statement The nucleoskeleton is critical for maintaining the architecture and functional integrity of the nucleus. Nonerythroid α-spectrin (αIISp) is an essential nucleoskeletal protein; however, its interactions with other structural and non-structural nuclear proteins and its functional importance in the nucleus have only begun to be explored. This review addresses these issues. It describes αIISp's association with DNA repair proteins and at least one proposed mechanism of action for its role in DNA repair. Specific interactions of αIISp with other nucleoskeletal proteins as well as its important role in the biomechanical properties of the nucleus are reviewed. The consequences of loss of αIISp, in disorders such as Fanconi anemia, are examined, providing insights into the profound impact of this loss on critical processes known to be abnormal in FA, such as development, carcinogenesis, cancer progression and cellular functions dependent upon αIISp's interactions with other nucleoskeletal proteins.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology and Laboratory Medicine, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ 07103, USA
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13
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Miguel-Aliaga I, Jasper H, Lemaitre B. Anatomy and Physiology of the Digestive Tract of Drosophila melanogaster. Genetics 2018; 210:357-396. [PMID: 30287514 PMCID: PMC6216580 DOI: 10.1534/genetics.118.300224] [Citation(s) in RCA: 247] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/26/2018] [Indexed: 12/15/2022] Open
Abstract
The gastrointestinal tract has recently come to the forefront of multiple research fields. It is now recognized as a major source of signals modulating food intake, insulin secretion and energy balance. It is also a key player in immunity and, through its interaction with microbiota, can shape our physiology and behavior in complex and sometimes unexpected ways. The insect intestine had remained, by comparison, relatively unexplored until the identification of adult somatic stem cells in the Drosophila intestine over a decade ago. Since then, a growing scientific community has exploited the genetic amenability of this insect organ in powerful and creative ways. By doing so, we have shed light on a broad range of biological questions revolving around stem cells and their niches, interorgan signaling and immunity. Despite their relatively recent discovery, some of the mechanisms active in the intestine of flies have already been shown to be more widely applicable to other gastrointestinal systems, and may therefore become relevant in the context of human pathologies such as gastrointestinal cancers, aging, or obesity. This review summarizes our current knowledge of both the formation and function of the Drosophila melanogaster digestive tract, with a major focus on its main digestive/absorptive portion: the strikingly adaptable adult midgut.
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Affiliation(s)
- Irene Miguel-Aliaga
- Medical Research Council London Institute of Medical Sciences, Imperial College London, W12 0NN, United Kingdom
| | - Heinrich Jasper
- Buck Institute for Research on Aging, Novato, California 94945-1400
- Immunology Discovery, Genentech, Inc., San Francisco, California 94080
| | - Bruno Lemaitre
- Global Health Institute, School of Life Sciences, École polytechnique fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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14
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Wang Q, Han TH, Nguyen P, Jarnik M, Serpe M. Tenectin recruits integrin to stabilize bouton architecture and regulate vesicle release at the Drosophila neuromuscular junction. eLife 2018; 7:35518. [PMID: 29901439 PMCID: PMC6040883 DOI: 10.7554/elife.35518] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/13/2018] [Indexed: 11/15/2022] Open
Abstract
Assembly, maintenance and function of synaptic junctions depend on extracellular matrix (ECM) proteins and their receptors. Here we report that Tenectin (Tnc), a Mucin-type protein with RGD motifs, is an ECM component required for the structural and functional integrity of synaptic specializations at the neuromuscular junction (NMJ) in Drosophila. Using genetics, biochemistry, electrophysiology, histology and electron microscopy, we show that Tnc is secreted from motor neurons and striated muscles and accumulates in the synaptic cleft. Tnc selectively recruits αPS2/βPS integrin at synaptic terminals, but only the cis Tnc/integrin complexes appear to be biologically active. These complexes have distinct pre- and postsynaptic functions, mediated at least in part through the local engagement of the spectrin-based membrane skeleton: the presynaptic complexes control neurotransmitter release, while postsynaptic complexes ensure the size and architectural integrity of synaptic boutons. Our study reveals an unprecedented role for integrin in the synaptic recruitment of spectrin-based membrane skeleton. Nerve cells or neurons can communicate with each other by releasing chemical messengers into the gap between them, the synapse. Both neurons and synapses are surrounded by a network of proteins called the extracellular matrix, which anchors, protects and supports the synapse. The matrix also helps to regulate the dynamic communication across the synapses and consequently neurons. Little is known about the proteins of the extracellular matrix, in particular about the ones involved in structural support. This is especially important for the so-called neuromuscular junctions, where neurons stimulate muscle contraction and trigger vigorous movement. Receptor proteins on cell surfaces, such as integrins, can bind to the extracellular matrix proteins to anchor the cells and are important for all cell junctions, including synaptic junctions. But because of their many essential roles during development, it was unclear how integrins modulate the activity of the synapse. To investigate this further, Wang et al. studied the neuromuscular junctions of fruit flies. The experiments revealed that both muscle and neurons secrete a large protein called Tenectin, which accumulates into the small space between the neuron and the muscle, the synaptic cleft. This protein can bind to integrin and is necessary to support the neuromuscular junction structurally and functionally. Wang et al. discovered that Tenectin works by gathering integrins on the surface of the neuron and the muscle. In the neuron, Tenectin forms complexes with integrin to regulate the release of neurotransmitters. In the muscle, the complexes provide support to the synaptic structures. However, when Tenectin was experimentally removed, it only disrupted the integrins at the neuromuscular junction, without affecting integrins in other regions of the cells, such as the site where the muscle uses integrins to attach to the tendon. Moreover, without Tenectin an important intracellular scaffolding meshwork that lines up and reinforces cell membranes was no longer organized properly at the synapse. A next step will be to identify the missing components between Tenectin/integrin complexes on the surface of neurons and the neurotransmitter release machinery inside the cells. The extracellular matrix and its receptors play fundamental roles in the development and function of the nervous system. A better knowledge of the underlying mechanisms will help us to better understand the complex interplay between the synapse and the extracellular matrix.
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Affiliation(s)
- Qi Wang
- Section on Cellular Communication, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Tae Hee Han
- Section on Cellular Communication, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Peter Nguyen
- Section on Cellular Communication, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Michal Jarnik
- Section on Intracellular Protein Trafficking, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Mihaela Serpe
- Section on Cellular Communication, Eunice Kennedy Shriver, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
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15
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Qu Y, Hahn I, Webb SED, Pearce SP, Prokop A. Periodic actin structures in neuronal axons are required to maintain microtubules. Mol Biol Cell 2016; 28:296-308. [PMID: 27881663 PMCID: PMC5231898 DOI: 10.1091/mbc.e16-10-0727] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/09/2016] [Accepted: 11/15/2016] [Indexed: 12/31/2022] Open
Abstract
Drosophila genetics is combined with high-resolution microscopy and a number of functional readouts to demonstrate key factors required for the presence of regularly spaced rings of cortical actin in axons. The data suggest important roles for the actin rings in microtubule regulation, most likely by sustaining their polymerization. Axons are cable-like neuronal processes wiring the nervous system. They contain parallel bundles of microtubules as structural backbones, surrounded by regularly spaced actin rings termed the periodic membrane skeleton (PMS). Despite being an evolutionarily conserved, ubiquitous, highly ordered feature of axons, the function of PMS is unknown. Here we studied PMS abundance, organization, and function, combining versatile Drosophila genetics with superresolution microscopy and various functional readouts. Analyses with 11 actin regulators and three actin-targeting drugs suggest that PMS contains short actin filaments that are depolymerization resistant and sensitive to spectrin, adducin, and nucleator deficiency, consistent with microscopy-derived models proposing PMS as specialized cortical actin. Upon actin removal, we observed gaps in microtubule bundles, reduced microtubule polymerization, and reduced axon numbers, suggesting a role of PMS in microtubule organization. These effects become strongly enhanced when carried out in neurons lacking the microtubule-stabilizing protein Short stop (Shot). Combining the aforementioned actin manipulations with Shot deficiency revealed a close correlation between PMS abundance and microtubule regulation, consistent with a model in which PMS-dependent microtubule polymerization contributes to their maintenance in axons. We discuss potential implications of this novel PMS function along axon shafts for axon maintenance and regeneration.
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Affiliation(s)
- Yue Qu
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Ines Hahn
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Stephen E D Webb
- Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot OX11 0QX, United Kingdom
| | - Simon P Pearce
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom.,School of Mathematics, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Andreas Prokop
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
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16
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Lambert MW. Nuclear alpha spectrin: Critical roles in DNA interstrand cross-link repair and genomic stability. Exp Biol Med (Maywood) 2016; 241:1621-38. [PMID: 27480253 PMCID: PMC4999628 DOI: 10.1177/1535370216662714] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Non-erythroid alpha spectrin (αIISp) is a structural protein which we have shown is present in the nucleus of human cells. It interacts with a number of nuclear proteins such as actin, lamin, emerin, chromatin remodeling factors, and DNA repair proteins. αIISp's interaction with DNA repair proteins has been extensively studied. We have demonstrated that nuclear αIISp is critical in DNA interstrand cross-link (ICL) repair in S phase, in both genomic (non-telomeric) and telomeric DNA, and in maintenance of genomic stability following ICL damage to DNA. We have proposed that αIISp acts as a scaffold aiding to recruit repair proteins to sites of damage. This involvement of αIISp in ICL repair and telomere maintenance after ICL damage represents new and critical functions for αIISp. These studies have led to development of a model for the role of αIISp in DNA ICL repair. They have been aided by examination of cells from patients with Fanconi anemia (FA), a repair-deficient genetic disorder in which a deficiency in αIISp leads to defective ICL repair in genomic and telomeric DNA, telomere dysfunction, and chromosome instability following DNA ICL damage. We have shown that loss of αIISp in FA cells is due to increased breakdown by the protease, µ-calpain. Importantly, we have demonstrated that this deficiency can be corrected by knockdown of µ-calpain and restoring αIISp levels to normal. This corrects a number of the phenotypic deficiencies in FA after ICL damage. These studies suggest a new and unexplored direction for therapeutically restoring genomic stability in FA cells and for correcting numerous phenotypic deficiencies occurring after ICL damage. Developing a more in-depth understanding of the importance of the interaction of αIISp with other nuclear proteins could significantly enhance our knowledge of the consequences of loss of αIISp on critical nuclear processes.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology and Laboratory Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
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17
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Lambert MW. Functional Significance of Nuclear α Spectrin. J Cell Biochem 2016; 116:1816-30. [PMID: 25757157 DOI: 10.1002/jcb.25123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 11/11/2022]
Abstract
Nonerythroid alpha spectrin (αIISp) interacts in the nucleus with an array of different proteins indicating its involvement in a number of diverse functions. However, the significance of these interactions and their functional importance has been a relatively unexplored area. The best documented role of nuclear αIISp is in DNA repair where it is critical for repair of DNA interstrand cross-links (ICLs), acting as a scaffold recruiting proteins to sites of damage in genomic and telomeric DNA. A deficiency in αIISp can importantly impact DNA ICL repair as is seen in cells from patients with the genetic disorder, Fanconi anemia (FA), where loss of αIISp leads to not only defects in repair of both genomic and telomeric DNA but also to telomere dysfunction and chromosome instability. This previously unexplored link between αIISp and telomere function is important in developing an understanding of maintenance of genomic stability after ICL damage. In FA cells, these defects in chromosome instability after ICL damage can be corrected when levels of αIISp are returned to normal by knocking down μ-calpain, a protease which cleaves αIISp. These studies suggest a new direction for correcting a number of the phenotypic defects in FA and could serve as a basis for therapeutic intervention. More in depth, examination of the interactions of αIISp with other proteins in the nucleus is of major importance in development of insights into the interacting key elements involved in the diverse processes occurring in the nucleus and the consequences loss of αIISp has on them.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology and Laboratory Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, New Jersey, 07103
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18
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Ng BF, Selvaraj GK, Santa-Cruz Mateos C, Grosheva I, Alvarez-Garcia I, Martín-Bermudo MD, Palacios IM. α-Spectrin and integrins act together to regulate actomyosin and columnarization, and to maintain a monolayered follicular epithelium. Development 2016; 143:1388-99. [PMID: 26952981 PMCID: PMC4852512 DOI: 10.1242/dev.130070] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 02/18/2016] [Indexed: 12/26/2022]
Abstract
The spectrin cytoskeleton crosslinks actin to the membrane, and although it has been greatly studied in erythrocytes, much is unknown about its function in epithelia. We have studied the role of spectrins during epithelia morphogenesis using the Drosophila follicular epithelium (FE). As previously described, we show that α-Spectrin and β-Spectrin are essential to maintain a monolayered FE, but, contrary to previous work, spectrins are not required to control proliferation. Furthermore, spectrin mutant cells show differentiation and polarity defects only in the ectopic layers of stratified epithelia, similar to integrin mutants. Our results identify α-Spectrin and integrins as novel regulators of apical constriction-independent cell elongation, as α-Spectrin and integrin mutant cells fail to columnarize. Finally, we show that increasing and reducing the activity of the Rho1-Myosin II pathway enhances and decreases multilayering of α-Spectrin cells, respectively. Similarly, higher Myosin II activity enhances the integrin multilayering phenotype. This work identifies a primary role for α-Spectrin in controlling cell shape, perhaps by modulating actomyosin. In summary, we suggest that a functional spectrin-integrin complex is essential to balance adequate forces, in order to maintain a monolayered epithelium.
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Affiliation(s)
- Bing Fu Ng
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Gokul Kannan Selvaraj
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | | | - Inna Grosheva
- Centro Andaluz de Biología del Desarrollo CSIC-Univ. Pablo de Olavide, Sevilla 41013, Spain
| | - Ines Alvarez-Garcia
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | | | - Isabel M Palacios
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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19
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Deng H, Wang W, Yu J, Zheng Y, Qing Y, Pan D. Spectrin regulates Hippo signaling by modulating cortical actomyosin activity. eLife 2015; 4:e06567. [PMID: 25826608 PMCID: PMC4412106 DOI: 10.7554/elife.06567] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/30/2015] [Indexed: 12/21/2022] Open
Abstract
The Hippo pathway controls tissue growth through a core kinase cascade that impinges on the transcription of growth-regulatory genes. Understanding how this pathway is regulated in development remains a major challenge. Recent studies suggested that Hippo signaling can be modulated by cytoskeletal tension through a Rok-myosin II pathway. How cytoskeletal tension is regulated or its relationship to the other known upstream regulators of the Hippo pathway remains poorly defined. In this study, we identify spectrin, a contractile protein at the cytoskeleton-membrane interface, as an upstream regulator of the Hippo signaling pathway. We show that, in contrast to canonical upstream regulators such as Crumbs, Kibra, Expanded, and Merlin, spectrin regulates Hippo signaling in a distinct way by modulating cortical actomyosin activity through non-muscle myosin II. These results uncover an essential mediator of Hippo signaling by cytoskeleton tension, providing a new entry point to dissecting how mechanical signals regulate Hippo signaling in living tissues. DOI:http://dx.doi.org/10.7554/eLife.06567.001 Organs including the liver, eyes, and lungs are made up of millions of cells, and how these organs stop growing once they reach their final size has fascinated scientists for decades. The cells in developing organs must communicate with each other and respond appropriately to the signals that they receive from other cells. This requires so-called “signaling pathways”. One such pathway that involves a protein called Hippo is known to control when cells should grow and divide and when they should stop. If this pathway does not work correctly, it can cause too many cells to be formed, which may result in cancer. The Hippo signaling pathway can also be regulated by an extensive network of protein filaments found within cells, called the cytoskeleton. This network can exert forces on the cells, which can have a major impact on cell growth. However, the mechanism behind the interaction between the cytoskeleton and the Hippo signaling pathway is poorly understood. Now, Deng et al. have engineered fruit flies in which the expression of individual genes had been artificially reduced, and looked for flies that had enlarged wings. Three genes identified in these experiments encode different subunits of a large spring-like protein, called spectrin, which is part of the cytoskeleton. This suggests that normally spectrin limits wing size. Furthermore, spectrin was also found to control the size of other organs in the fruit flies, such as the eyes and ovaries. In all of these organs, the Hippo signaling pathway failed to work properly in the absence of spectrin. Deng et al. then further explored the relationship between spectrin and Hippo signaling and found that cells without spectrin show abnormally high levels of tension in their cytoskeleton. When flies that lacked spectrin were engineered to reduce this tension, these flies developed normal sized organs. These findings reveal the importance of cytoskeleton tension in controlling tissue growth, and provide a new entry point to understand how normal tissues grow to their characteristic size and how such process goes awry in cancer. DOI:http://dx.doi.org/10.7554/eLife.06567.002
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Affiliation(s)
- Hua Deng
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Wei Wang
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Jianzhong Yu
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Yonggang Zheng
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Yun Qing
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Duojia Pan
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
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20
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Wong KKL, Li W, An Y, Duan Y, Li Z, Kang Y, Yan Y. β-Spectrin regulates the hippo signaling pathway and modulates the basal actin network. J Biol Chem 2015; 290:6397-407. [PMID: 25589787 DOI: 10.1074/jbc.m114.629493] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Emerging evidence suggests functional regulation of the Hippo pathway by the actin cytoskeleton, although the detailed molecular mechanism remains incomplete. In a genetic screen, we identified a requirement for β-Spectrin in the posterior follicle cells for the oocyte repolarization process during Drosophila mid-oogenesis. β-spectrin mutations lead to loss of Hippo signaling activity in the follicle cells. A similar reduction of Hippo signaling activity was observed after β-Spectrin knockdown in mammalian cells. We further demonstrated that β-spectrin mutations disrupt the basal actin network in follicle cells. The abnormal stress fiber-like actin structure on the basal side of follicle cells provides a likely link between the β-spectrin mutations and the loss of the Hippo signaling activity phenotype.
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Affiliation(s)
- Kenneth Kin Lam Wong
- From the Division of Life Science and Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and
| | - Wenyang Li
- the Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544
| | - Yanru An
- From the Division of Life Science and Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and
| | | | | | - Yibin Kang
- the Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544
| | - Yan Yan
- From the Division of Life Science and Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China and
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21
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Khanna MR, Mattie FJ, Browder KC, Radyk MD, Crilly SE, Bakerink KJ, Harper SL, Speicher DW, Thomas GH. Spectrin tetramer formation is not required for viable development in Drosophila. J Biol Chem 2014; 290:706-15. [PMID: 25381248 DOI: 10.1074/jbc.m114.615427] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The dominant paradigm for spectrin function is that (αβ)2-spectrin tetramers or higher order oligomers form membrane-associated two-dimensional networks in association with F-actin to reinforce the plasma membrane. Tetramerization is an essential event in such structures. We characterize the tetramerization interaction between α-spectrin and β-spectrins in Drosophila. Wild-type α-spectrin binds to both β- and βH-chains with high affinity, resembling other non-erythroid spectrins. However, α-spec(R22S), a tetramerization site mutant homologous to the pathological α-spec(R28S) allele in humans, eliminates detectable binding to β-spectrin and reduces binding to βH-spectrin ∼1000-fold. Even though spectrins are essential proteins, α-spectrin(R22S) rescues α-spectrin mutants to adulthood with only minor phenotypes indicating that tetramerization, and thus conventional network formation, is not the essential function of non-erythroid spectrin. Our data provide the first rigorous test for the general requirement for tetramer-based non-erythroid spectrin networks throughout an organism and find that they have very limited roles, in direct contrast to the current paradigm.
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Affiliation(s)
- Mansi R Khanna
- From the Department of Biology and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Floyd J Mattie
- From the Department of Biology and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Kristen C Browder
- From the Department of Biology and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Megan D Radyk
- From the Department of Biology and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Stephanie E Crilly
- From the Department of Biology and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Katelyn J Bakerink
- From the Department of Biology and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Sandra L Harper
- the Systems Biology Division, The Wistar Institute, Philadelphia, Pennsylvania 19104
| | - David W Speicher
- the Systems Biology Division, The Wistar Institute, Philadelphia, Pennsylvania 19104
| | - Graham H Thomas
- From the Department of Biology and the Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802 and
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22
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Chen ZF, Zhang H, Wang H, Matsumura K, Wong YH, Ravasi T, Qian PY. Quantitative proteomics study of larval settlement in the Barnacle Balanus amphitrite. PLoS One 2014; 9:e88744. [PMID: 24551147 PMCID: PMC3923807 DOI: 10.1371/journal.pone.0088744] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/08/2014] [Indexed: 01/06/2023] Open
Abstract
Barnacles are major sessile components of the intertidal areas worldwide, and also one of the most dominant fouling organisms in fouling communities. Larval settlement has a crucial ecological effect not only on the distribution of the barnacle population but also intertidal community structures. However, the molecular mechanisms involved in the transition process from the larval to the juvenile stage remain largely unclear. In this study, we carried out comparative proteomic profiles of stage II nauplii, stage VI nauplii, cyprids, and juveniles of the barnacle Balanus amphitrite using label-free quantitative proteomics, followed by the measurement of the gene expression levels of candidate proteins. More than 700 proteins were identified at each stage; 80 were significantly up-regulated in cyprids and 95 in juveniles vs other stages. Specifically, proteins involved in energy and metabolism, the nervous system and signal transduction were significantly up-regulated in cyprids, whereas proteins involved in cytoskeletal remodeling, transcription and translation, cell proliferation and differentiation, and biomineralization were up-regulated in juveniles, consistent with changes associated with larval metamorphosis and tissue remodeling in juveniles. These findings provided molecular evidence for the morphological, physiological and biological changes that occur during the transition process from the larval to the juvenile stages in B. amphitrite.
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Affiliation(s)
- Zhang-Fan Chen
- KAUST Global Collaborative Research Program, Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Huoming Zhang
- Bioscience Core Laboratory, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Hao Wang
- KAUST Global Collaborative Research Program, Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Kiyotaka Matsumura
- KAUST Global Collaborative Research Program, Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Yue Him Wong
- KAUST Global Collaborative Research Program, Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Timothy Ravasi
- Integrative Systems Biology Lab, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Pei-Yuan Qian
- KAUST Global Collaborative Research Program, Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong SAR, China
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23
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Hinrichsen I, Ernst BP, Nuber F, Passmann S, Schäfer D, Steinke V, Friedrichs N, Plotz G, Zeuzem S, Brieger A. Reduced migration of MLH1 deficient colon cancer cells depends on SPTAN1. Mol Cancer 2014; 13:11. [PMID: 24456667 PMCID: PMC3904401 DOI: 10.1186/1476-4598-13-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 01/17/2014] [Indexed: 01/13/2023] Open
Abstract
Introduction Defects in the DNA mismatch repair (MMR) protein MLH1 are frequently observed in sporadic and hereditary colorectal cancers (CRC). Affected tumors generate much less metastatic potential than the MLH1 proficient forms. Although MLH1 has been shown to be not only involved in postreplicative MMR but also in several MMR independent processes like cytoskeletal organization, the connection between MLH1 and metastasis remains unclear. We recently identified non-erythroid spectrin αII (SPTAN1), a scaffolding protein involved in cell adhesion and motility, to interact with MLH1. In the current study, the interaction of MLH1 and SPTAN1 and its potential consequences for CRC metastasis was evaluated. Methods Nine cancer cell lines as well as fresh and paraffin embedded colon cancer tissue from 12 patients were used in gene expression studies of SPTAN1 and MLH1. Co-expression of SPTAN1 and MLH1 was analyzed by siRNA knock down of MLH1 in HeLa, HEK293, MLH1 positive HCT116, SW480 and LoVo cells. Effects on cellular motility were determined in MLH1 deficient HCT116 and MLH1 deficient HEK293T compared to their MLH1 proficient sister cells, respectively. Results MLH1 deficiency is clearly associated with SPTAN1 reduction. Moreover, siRNA knock down of MLH1 decreased the mRNA level of SPTAN1 in HeLa, HEK293 as well as in MLH1 positive HCT116 cells, which indicates a co-expression of SPTAN1 by MLH1. In addition, cellular motility of MLH1 deficient HCT116 and MLH1 deficient HEK293T cells was impaired compared to the MLH1 proficient sister clones. Consequently, overexpression of SPTAN1 increased migration of MLH1 deficient cells while knock down of SPTAN1 decreased cellular mobility of MLH1 proficient cells, indicating SPTAN1-dependent migration ability. Conclusions These data suggest that SPTAN1 levels decreased in concordance with MLH1 reduction and impaired cellular mobility in MLH1 deficient colon cancer cells. Therefore, aggressiveness of MLH1-positive CRC might be related to SPTAN1.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Angela Brieger
- Medical Clinic I, Biomedical Research Laboratory, Goethe-University, Frankfurt a,M, Germany.
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24
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Genetic studies of spectrin in the larval fat body of Drosophila melanogaster: evidence for a novel lipid uptake apparatus. Genetics 2013; 195:871-81. [PMID: 24037266 DOI: 10.1534/genetics.113.155192] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spectrin cytoskeleton defects produce a host of phenotypes affecting the plasma membrane, cell polarity, and secretory membrane traffic. However, many of the underlying molecular mechanisms remain unexplained by prevailing models. Here we used the larval fat body of Drosophila melanogaster as a genetic model system to further elucidate mechanisms of αβ-spectrin function. The results provide unexpected new insights into spectrin function as well as mechanisms of dietary fat uptake and storage. We show that loss of α- or β-spectrin in the fat body eliminated a population of small cortical lipid droplets and altered plasma membrane architecture, but did not affect viability of the organism. We present a novel model in which αβ-spectrin directly couples lipid uptake at the plasma membrane to lipid droplet growth in the cytoplasm. In contrast, strong overexpression of β-spectrin caused fat body atrophy and larval lethality. Overexpression of β-spectrin also perturbed transport of dietary fat from the midgut to the fat body. This hypermorphic phenotype appears to be the result of blocking secretion of the lipid carrier lipophorin from fat cells. However, this midgut phenotype was never seen with spectrin loss of function, suggesting that spectrin is not normally required for lipophorin secretion or function. The β-spectrin hypermorphic phenotype was ameliorated by co-overexpression of α-spectrin. Based on the overexpression results here, we propose that β-spectrin family members may be prone to hypermorphic effects (including effects on secretion) if their activity is not properly regulated.
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25
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Papal S, Cortese M, Legendre K, Sorusch N, Dragavon J, Sahly I, Shorte S, Wolfrum U, Petit C, El-Amraoui A. The giant spectrin βV couples the molecular motors to phototransduction and Usher syndrome type I proteins along their trafficking route. Hum Mol Genet 2013; 22:3773-88. [PMID: 23704327 DOI: 10.1093/hmg/ddt228] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutations in the myosin VIIa gene cause Usher syndrome type IB (USH1B), characterized by deaf-blindness. A delay of opsin trafficking has been observed in the retinal photoreceptor cells of myosin VIIa-deficient mice. We identified spectrin βV, the mammalian β-heavy spectrin, as a myosin VIIa- and rhodopsin-interacting partner in photoreceptor cells. Spectrin βV displays a polarized distribution from the Golgi apparatus to the base of the outer segment, which, unlike that of other β spectrins, matches the trafficking route of opsin and other phototransduction proteins. Formation of spectrin βV-rhodopsin complex could be detected in the differentiating photoreceptors as soon as their outer segment emerges. A failure of the spectrin βV-mediated coupling between myosin VIIa and opsin molecules thus probably accounts for the opsin transport delay in myosin VIIa-deficient mice. We showed that spectrin βV also associates with two USH1 proteins, sans (USH1G) and harmonin (USH1C). Spectrins are supposed to function as heteromers of α and β subunits, but fluorescence resonance energy transfer and in vitro binding experiments indicated that spectrin βV can also form homodimers, which likely supports its αII-independent βV functions. Finally, consistent with its distribution along the connecting cilia axonemes, spectrin βV binds to several subunits of the microtubule-based motor proteins, kinesin II and the dynein complex. We therefore suggest that spectrin βV homomers couple some USH1 proteins, opsin and other phototransduction proteins to both actin- and microtubule-based motors, thereby contributing to their transport towards the photoreceptor outer disks.
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Affiliation(s)
- Samantha Papal
- Institut Pasteur, Unité de génétique et physiologie de l'audition, Paris, France
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Frazzled/DCC facilitates cardiac cell outgrowth and attachment during Drosophila dorsal vessel formation. Dev Biol 2013; 380:233-42. [PMID: 23685255 DOI: 10.1016/j.ydbio.2013.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 04/29/2013] [Accepted: 05/07/2013] [Indexed: 01/30/2023]
Abstract
Drosophila embryonic dorsal vessel (DV) morphogenesis is a highly stereotyped process that involves the migration and morphogenesis of 52 pairs of cardioblasts (CBs) in order to form a linear tube. This process requires spatiotemporally-regulated localization of signaling and adhesive proteins in order to coordinate the formation of a central lumen while maintaining simultaneous adhesion between CBs. Previous studies have shown that the Slit/Roundabout and Netrin/Unc5 repulsive signaling pathways facilitate site-specific loss of adhesion between contralateral CBs in order to form a luminal space. However, the concomitant mechanism by which attraction initiates CB outgrowth and discrete localization of adhesive proteins remains poorly understood. Here we provide genetic evidence that Netrin signals through DCC (Deleted in Colorectal Carcinoma)/UNC-40/Frazzled (Fra) to mediate CB outgrowth and attachment and that this function occurs prior to and independently of Netrin/UNC-5 signaling. fra mRNA is expressed in the CBs prior to and during DV morphogenesis. Loss-of-fra-function results in significant defects in cell shape and alignment between contralateral CB rows. In addition, CB outgrowth and attachment is impaired in both fra loss- and gain-of-function mutants. Deletion of both Netrin genes (NetA and NetB) results in CB attachment phenotypes similar to fra mutants. Similar defects are also seen when both fra and unc5 are deleted. Finally we show that Fra accumulates at dorsal and ventral leading edges of paired CBs, and this localization is dependent upon Netrin. We propose that while repulsive guidance mechanisms contribute to lumen formation by preventing luminal domains from coming together, site-specific Netrin/Frazzled signaling mediates CB attachment.
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27
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Zhang P, Herbig U, Coffman F, Lambert MW. Non-erythroid alpha spectrin prevents telomere dysfunction after DNA interstrand cross-link damage. Nucleic Acids Res 2013; 41:5321-40. [PMID: 23571757 PMCID: PMC3664817 DOI: 10.1093/nar/gkt235] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Telomere integrity is critical for telomere function and genomic stability. We previously demonstrated that non-erythroid α-spectrin (αIISp) is present in mammalian cell nuclei where it is important in repair of DNA interstrand cross-links (ICLs) and chromosome stability. We now demonstrate that αIISp is also important for telomere maintenance after ICL damage. It localizes to telomeres in S phase after ICL damage where it has enhanced association with TRF1 and TRF2 and is required for recruitment of the ICL repair protein, XPF, to damage-induced foci at telomeres. In telomerase-positive normal cells depleted of αIISp by siRNA or in Fanconi anemia, complementation group A (FA-A) cells, where αIISp levels are 35–40% of normal, ICL damage results in failure of XPF to localize to telomeres, markedly increased telomere dysfunction-induced foci, followed by catastrophic loss of telomeres. Restoration of αIISp levels to normal in FA-A cells corrects these deficiencies. Our studies demonstrate that αIISp is critical for repair of DNA ICLs at telomeres, likely by facilitating the recruitment of repair proteins similar, but not identical, to its proposed role in repair of DNA ICLs in genomic DNA and that this function in turn is critical for telomere maintenance after DNA ICL damage.
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Affiliation(s)
- Pan Zhang
- Department of Pathology and Laboratory Medicine, UMDNJ - New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07042, USA
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28
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Hollomon DW. Do we have the tools to manage resistance in the future? PEST MANAGEMENT SCIENCE 2012; 68:149-154. [PMID: 22223198 DOI: 10.1002/ps.2291] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Pesticide resistance is a major factor affecting world food and fibre production, but that has been contained so far by the availability of diverse modes of action. Overcoming resistance by switching to a new mode of action is a concept easily grasped by growers but threatened by losses through resistance and new registration requirements. Opportunities for innovation and development of a diversity of novel modes of action exist through harnessing recent advances, fundamental to all eukaryotes and largely funded for medical rather than agricultural objectives, in understanding cell biology and development. The cystoskeleton, cell wall synthesis, signal transduction and RNAi are discussed as examples where new targets are now exposed. However, new modes of action will be delivered not only by sprayer or seed treatment but also through transgenic crops, although these still need to be transferred from experiment to practice. Improvements in modelling protein structures and target-site changes, supplemented by rapid diagnostics to detect resistance early, will improve resistance risk management and integrate chemical, biopesticide, transgenic and conventional breeding around the concept of diversity in modes of action. However, before agronomy can translate this into practical antiresistance strategies, there is a need to direct more resources to the biochemistry and cell biology of pests, diseases and weeds to translate these new discoveries into key tools needed to manage resistance in the future.
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29
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Xu P, Johnson TL, Stoller-Conrad JR, Schulz RA. Spire, an actin nucleation factor, regulates cell division during Drosophila heart development. PLoS One 2012; 7:e30565. [PMID: 22276214 PMCID: PMC3262839 DOI: 10.1371/journal.pone.0030565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 12/19/2011] [Indexed: 11/18/2022] Open
Abstract
The Drosophila dorsal vessel is a beneficial model system for studying the regulation of early heart development. Spire (Spir), an actin-nucleation factor, regulates actin dynamics in many developmental processes, such as cell shape determination, intracellular transport, and locomotion. Through protein expression pattern analysis, we demonstrate that the absence of spir function affects cell division in Myocyte enhancer factor 2-, Tinman (Tin)-, Even-skipped- and Seven up (Svp)-positive heart cells. In addition, genetic interaction analysis shows that spir functionally interacts with Dorsocross, tin, and pannier to properly specify the cardiac fate. Furthermore, through visualization of double heterozygous embryos, we determines that spir cooperates with CycA for heart cell specification and division. Finally, when comparing the spir mutant phenotype with that of a CycA mutant, the results suggest that most Svp-positive progenitors in spir mutant embryos cannot undergo full cell division at cell cycle 15, and that Tin-positive progenitors are arrested at cell cycle 16 as double-nucleated cells. We conclude that Spir plays a crucial role in controlling dorsal vessel formation and has a function in cell division during heart tube morphogenesis.
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Affiliation(s)
- Peng Xu
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America.
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30
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Wang X, Yang F, Liu C, Zhou H, Wu G, Qiao S, Li D, Wang J. Dietary supplementation with the probiotic Lactobacillus fermentum I5007 and the antibiotic aureomycin differentially affects the small intestinal proteomes of weanling piglets. J Nutr 2012; 142:7-13. [PMID: 22113866 DOI: 10.3945/jn.111.147074] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Antibiotics have long been used in animal production and medication to alleviate weaning stress. However, due to the concerns over food safety and human health, its use in animal production has been prohibited in many countries. Therefore, there is growing interest in developing alternative additives, such as a probiotic Lactobacillus. In this study, a proteomic approach coupled with biochemical analysis was applied to investigate alterations of proteomes in the small intestinal mucosa of weanling piglets after a 13-d period of feeding with supplemental L. fermentum I5007 or aureomycin (an antibiotic). We indentified 27 differentially expressed protein spots that participated in 7 key biological processes, including: 1) energy metabolism; 2) lipid metabolism; 3) protein synthesis; 4) cell structure and mobility; 5) cellular proliferation and apoptosis; 6) immune response; and 7) stress response and detoxification. Both L. fermentum I5007 and aureomycin decreased the expression of proteins related to apoptosis, stress response, and increased the expression of proteins related to detoxification in the gastrointestinal (GI) tract of weanling piglets. L. fermentum I5007 exhibited additional effects in alleviating weaning stress syndrome by enhancing the levels of proteins involved in energy metabolism, lipid metabolism, cell structure and mobility, protein synthesis, and immune response, thereby facilitating cellular proliferation and depressing apoptosis. In contrast, aureomycin reduced the levels of proteins related to energy metabolism, protein synthesis, cell structure, motility, and immunity. These novel findings have important implications for understanding the mechanisms whereby L. fermentum I5007 can improve the GI health of postweaning piglets.
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Affiliation(s)
- Xiaoqiu Wang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, China
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31
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Non-erythroid beta spectrin interacting proteins and their effects on spectrin tetramerization. Cell Mol Biol Lett 2011; 16:595-609. [PMID: 21866423 PMCID: PMC3675649 DOI: 10.2478/s11658-011-0025-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 08/18/2011] [Indexed: 11/20/2022] Open
Abstract
With yeast two-hybrid methods, we used a C-terminal fragment (residues 1697–2145) of non-erythroid beta spectrin (βII-C), including the region involved in the association with alpha spectrin to form tetramers, as the bait to screen a human brain cDNA library to identify proteins interacting with βII-C. We applied stringent selection steps to eliminate false positives and identified 17 proteins that interacted with βII-C (IPβII-C s). The proteins include a fragment (residues 38–284) of “THAP domain containing, apoptosis associated protein 3, isoform CRA g”, “glioma tumor suppressor candidate region gene 2” (residues 1-478), a fragment (residues 74–442) of septin 8 isoform c, a fragment (residues 704–953) of “coatomer protein complex, subunit beta 1, a fragment (residues 146–614) of zinc-finger protein 251, and a fragment (residues 284–435) of syntaxin binding protein 1. We used yeast three-hybrid system to determine the effects of these βII-C interacting proteins as well as of 7 proteins previously identified to interact with the tetramerization region of non-erythroid alpha spectrin (IPαII-N s) [1] on spectrin tetramer formation. The results showed that 3 IPβII-C s were able to bind βII-C even in the presence of αII-N, and 4 IPαII-N s were able to bind αII-N in the presence of βII-C. We also found that the syntaxin binding protein 1 fragment abolished αII-N and βII-C interaction, suggesting that this protein may inhibit or regulate non-erythroid spectrin tetramer formation.
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Loss of lysine-specific demethylase 1 nonautonomously causes stem cell tumors in the Drosophila ovary. Proc Natl Acad Sci U S A 2011; 108:7064-9. [PMID: 21482791 DOI: 10.1073/pnas.1015874108] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Specialized microenvironments called niches keep stem cells in an undifferentiated and self-renewing state. Dedicated stromal cells form niches by producing a variety of factors that act directly on stem cells. The size and signaling output of niches must be finely tuned to ensure proper tissue homeostasis. Although advances have been made in identifying factors that promote niche cell fate, the mechanisms that restrict niche cell formation during development and limit niche signaling output in adults remain poorly understood. Here, we show that the histone lysine-specific demethylase 1 (Lsd1) regulates the size of the germline stem cell (GSC) niche in Drosophila ovaries. GSC maintenance depends on bone morphogenetic protein (BMP) signals produced by a small cluster of cap cells located at the anterior tip of the germarium. Lsd1 null mutant ovaries carry small germline tumors containing an expanded number of GSC-like cells with round fusomes that display ectopic BMP signal responsiveness away from the normal niche. Clonal analysis and cell type-specific rescue experiments demonstrate that Lsd1 functions within the escort cells (ECs) that reside immediately adjacent to cap cells and prevents them from ectopically producing niche-specific signals. Temporally restricted gene knockdown experiments suggest that Lsd1 functions both during development, to specify EC fate, and in adulthood, to prevent ECs from forming ectopic niches independent of changes in cell fate. Further analysis shows that Lsd1 functions to repress decapentaplegic (dpp) expression in adult germaria. The role of Lsd1 in regulating niche-specific signals may have important implications for understanding how disruption of its mammalian homolog contributes to cancer and metastasis.
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Inter-subunit interactions in erythroid and non-erythroid spectrins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:420-7. [DOI: 10.1016/j.bbapap.2010.12.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 12/09/2010] [Accepted: 12/22/2010] [Indexed: 11/19/2022]
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34
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Morrow JS, Rimm DL, Kennedy SP, Cianci CD, Sinard JH, Weed SA. Of Membrane Stability and Mosaics: The Spectrin Cytoskeleton. Compr Physiol 2011. [DOI: 10.1002/cphy.cp140111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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35
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Baines A. Evolution of the spectrin-based membrane skeleton. Transfus Clin Biol 2010; 17:95-103. [DOI: 10.1016/j.tracli.2010.06.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 06/23/2010] [Indexed: 12/16/2022]
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36
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Baines AJ. The spectrin-ankyrin-4.1-adducin membrane skeleton: adapting eukaryotic cells to the demands of animal life. PROTOPLASMA 2010; 244:99-131. [PMID: 20668894 DOI: 10.1007/s00709-010-0181-1] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 07/05/2010] [Indexed: 05/29/2023]
Abstract
The cells in animals face unique demands beyond those encountered by their unicellular eukaryotic ancestors. For example, the forces engendered by the movement of animals places stresses on membranes of a different nature than those confronting free-living cells. The integration of cells into tissues, as well as the integration of tissue function into whole animal physiology, requires specialisation of membrane domains and the formation of signalling complexes. With the evolution of mammals, the specialisation of cell types has been taken to an extreme with the advent of the non-nucleated mammalian red blood cell. These and other adaptations to animal life seem to require four proteins--spectrin, ankyrin, 4.1 and adducin--which emerged during eumetazoan evolution. Spectrin, an actin cross-linking protein, was probably the earliest of these, with ankyrin, adducin and 4.1 only appearing as tissues evolved. The interaction of spectrin with ankyrin is probably a prerequisite for the formation of tissues; only with the advent of vertebrates did 4.1 acquires the ability to bind spectrin and actin. The latter activity seems to allow the spectrin complex to regulate the cell surface accumulation of a wide variety of proteins. Functionally, the spectrin-ankyrin-4.1-adducin complex is implicated in the formation of apical and basolateral domains, in aspects of membrane trafficking, in assembly of certain signalling and cell adhesion complexes and in providing stability to otherwise mechanically fragile cell membranes. Defects in this complex are manifest in a variety of hereditary diseases, including deafness, cardiac arrhythmia, spinocerebellar ataxia, as well as hereditary haemolytic anaemias. Some of these proteins also function as tumor suppressors. The spectrin-ankyrin-4.1-adducin complex represents a remarkable system that underpins animal life; it has been adapted to many different functions at different times during animal evolution.
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Affiliation(s)
- Anthony J Baines
- School of Biosciences and Centre for Biomedical Informatics, University of Kent, Canterbury, CT2 7NJ, UK.
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37
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Zhang P, Sridharan D, Lambert MW. Knockdown of mu-calpain in Fanconi anemia, FA-A, cells by siRNA restores alphaII spectrin levels and corrects chromosomal instability and defective DNA interstrand cross-link repair. Biochemistry 2010; 49:5570-81. [PMID: 20518497 DOI: 10.1021/bi100656j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We have previously shown that there is a deficiency in the structural protein, nonerythroid alpha spectrin (alphaIISp), in cells from patients with Fanconi anemia (FA). These studies indicate that this deficiency is due to the reduced stability of alphaIISp and correlates with a decreased level of repair of DNA interstrand cross-links and chromosomal instability in FA cells. An important factor in the stability of alphaIISp is its susceptibility to cleavage by the protease, mu-calpain. We hypothesized that an increased level of mu-calpain cleavage of alphaIISp in FA cells leads to an increased level of breakdown of alphaIISp and that knocking down expression of mu-calpain in FA cells should restore levels of alphaIISp and correct a number of the phenotypic defects observed. The results showed that there is increased mu-calpain activity in FA-A, FA-C, FA-D2, FA-F, and FA-G cells that could account for the deficiency in alphaIISp in these FA cells. Protein interaction studies indicated that FANCA and FANCG bind directly to mu-calpain. We hypothesize that this binding may lead to inhibition of mu-calpain activity in normal cells. Knocking down mu-calpain by siRNA in FA-A cells restored levels of alphaIISp to normal and reversed a number of the cellular deficiencies in these cells. It corrected the DNA repair defect and the chromosomal instability observed after exposure to a DNA interstrand cross-linking agent. These studies indicate that FA proteins may play an important role in maintaining the stability of alphaIISp in the cell by regulating its cleavage by mu-calpain. Thus, by reducing the level of breakdown of alphaIISp in FA cells, we may be able to reverse a number of the cellular deficiencies observed in this disorder.
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Affiliation(s)
- Pan Zhang
- Department of Pathology and Laboratory Medicine, New Jersey Medical School and Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103, USA
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38
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Mazock GH, Das A, Base C, Dubreuil RR. Transgene rescue identifies an essential function for Drosophila beta spectrin in the nervous system and a selective requirement for ankyrin-2-binding activity. Mol Biol Cell 2010; 21:2860-8. [PMID: 20573981 PMCID: PMC2921109 DOI: 10.1091/mbc.e10-03-0180] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The Gal4-UAS system was used to overexpress or knock down β spectrin with dsRNA in a variety of Drosophila tissues. Unexpectedly, overexpression in most tissues tested was lethal, whereas knockdown failed to produce a detectable phenotype in the same tissues. The lethality of a β spectrin mutation was rescued by expression of β spectrin in neurons. The protein spectrin is ubiquitous in animal cells and is believed to play important roles in cell shape and membrane stability, cell polarity, and endomembrane traffic. Experiments here were undertaken to identify sites of essential β spectrin function in Drosophila and to determine whether spectrin and ankyrin function are strictly linked to one another. The Gal4-UAS system was used to drive tissue-specific overexpression of a β spectrin transgene or to knock down β spectrin expression with dsRNA. The results show that 1) overexpression of β spectrin in most of the cell types studied was lethal; 2) knockdown of β spectrin in most tissues had no detectable effect on growth or viability of the organism; and 3) nervous system-specific expression of a UAS-β spectrin transgene was sufficient to overcome the lethality of a loss-of-function β spectrin mutation. Thus β spectrin expression in other cells was not required for development of fertile adult males, although females lacking nonneuronal spectrin were sterile. Previous data indicated that binding of the DAnk1 isoform of ankyrin to spectrin was partially dispensable for viability. Domain swap experiments here uncovered a different requirement for neuronal DAnk2 binding to spectrin and establish that DAnk2-binding is critical for β spectrin function in vivo.
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Affiliation(s)
- G Harper Mazock
- Department of Biological Sciences and Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, IL 60607, USA
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39
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Vaccaro MC, Gigliotti S, Graziani F, Carotenuto R, De Angelis C, Tussellino M, Campanella C. A transient asymmetric distribution of XNOA 36 mRNA and the associated spectrin network bisects Xenopus laevis stage I oocytes along the future A/V axis. Eur J Cell Biol 2010; 89:525-36. [PMID: 20226562 DOI: 10.1016/j.ejcb.2009.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 12/09/2009] [Accepted: 12/09/2009] [Indexed: 01/10/2023] Open
Abstract
In Xenopus oogenesis, the mechanisms governing the localisation of molecules crucial for primary axis determination have been uncovered in recent years. In stage I oocytes, the mitochondrial cloud (MC) entraps RNAs implicated in germ line specification and other RNAs, such as Xwnt-11 and Xlsirts, that are later delivered to the vegetal pole. Microfilaments and microtubules gradually develop in the cytoplasm, sustaining organelles as well as the MC. At stage III, other mRNAs migrate to the vegetal hemisphere through a microtubule-dependent mechanism. We report here the isolation of a cDNA encoding XNOA 36, a highly conserved protein, whose function is to date not fully understood. The XNOA 36 transcript is abundantly accumulated in stage I oocytes where it decorates a filamentous network. At the end of stage I the transcript gradually segregates in a sector of the oocyte surrounding the MC and opposite the ovarian hylum. Here, XNOA 36 mRNA distributes in a gradient-like pattern extending from a peripheral network towards the interior of the oocyte. This distribution is similar to that of alpha-spectrin mRNA. Both mRNAs are segregated in one half of the 250 microm oocytes, with the MC located between the XNOA 36/alpha-spectrin mRNA-labelled and unlabelled regions. XNOA 36 mRNA localisation was uncoupled from that of alpha-spectrin mRNA by cytochalasin B or ice-nocodazole treatments, suggesting that the two transcripts rely on different mechanisms for their localisation. However, immunolocalisation experiments coupled with in situ hybridisation revealed that the XNOA 36 transcript co-localises with the protein spectrin. This observation, together with the finding that XNOA 36 mRNA co-precipitates with spectrin, indicates that these two molecules interact physically. In conclusion, our data suggest that XNOA 36 mRNA is localized and/or anchored in the oocyte through a cytoskeletal network containing spectrin. The putative implications of this finding are discussed.
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Affiliation(s)
- M C Vaccaro
- Department of Structural and Functional Biology, University of Naples Federico II, Italy
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40
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Chen TW, Chen G, Funkhouser LJ, Nam SC. Membrane domain modulation by Spectrins in Drosophila photoreceptor morphogenesis. Genesis 2010; 47:744-50. [PMID: 19672952 DOI: 10.1002/dvg.20555] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Spectrins are major proteins in the cytoskeletal network of most cells. In Drosophila, beta(Heavy)-Spectrin encoded by the karst gene functions together with Crb during photoreceptor morphogenesis. However, the roles of two other Spectrins (alpha- and beta-Spectrins) in developing photoreceptor cells have not been studied. Here, we analyzed the effects of spectrin mutations on developing eyes to determine their roles in photoreceptor morphogenesis. We found that the Spectrins are dispensable for retinal differentiation in eye imaginal discs during larval stage. However, photoreceptors deficient in alpha- or beta-Spectrin display dramatic apical membrane expansions including Crb and show morphogenesis defects during pupal eye development, suggesting that alpha- and beta-Spectrins are specifically required for photoreceptor polarity during pupal eye development. Karst localizes apically, whereas beta-Spectrin is preferentially distributed in the basolateral region. We show that overexpression of beta-Spectrin causes a strong shrinkage of apical membrane domains, and loss of beta-Spectrin causes an expansion of apical domains, implying an antagonistic relationship between beta-Spectrin and Karst. These results indicate that Spectrins are required for controlling photoreceptor morphogenesis through the modulations of cell membrane domains.
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Affiliation(s)
- Tony W Chen
- Department of Biology, Baylor University, Waco, Texas 76798, USA
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Maynard JC, Pham T, Zheng T, Jockheck-Clark A, Rankin HB, Newgard CB, Spana EP, Nicchitta CV. Gp93, the Drosophila GRP94 ortholog, is required for gut epithelial homeostasis and nutrient assimilation-coupled growth control. Dev Biol 2010; 339:295-306. [PMID: 20044986 DOI: 10.1016/j.ydbio.2009.12.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 12/14/2009] [Accepted: 12/17/2009] [Indexed: 11/18/2022]
Abstract
GRP94, the endoplasmic reticulum Hsp90, is a metazoan-restricted chaperone essential for early development in mammals, yet dispensable for mammalian cell viability. This dichotomy suggests that GRP94 is required for the functional expression of secretory and/or membrane proteins that enable the integration of cells into tissues. To explore this hypothesis, we have identified the Drosophila ortholog of GRP94, Gp93, and report that Gp93 is an essential gene in Drosophila. Loss of zygotic Gp93 expression is late larval-lethal and causes prominent defects in the larval midgut, the sole endoderm-derived larval tissue. Gp93 mutant larvae display pronounced defects in the midgut epithelium, with aberrant copper cell structure, markedly reduced gut acidification, atypical septate junction structure, depressed gut motility, and deficits in intestinal nutrient uptake. The metabolic consequences of the loss of Gp93-expression are profound; Gp93 mutant larvae exhibit a starvation-like metabolic phenotype, including suppression of insulin signaling and extensive mobilization of amino acids and triglycerides. The defects in copper cell structure/function accompanying loss of Gp93 expression resemble those reported for mutations in labial, an endodermal homeotic gene required for copper cell specification, and alpha-spectrin, thus suggesting an essential role for Gp93 in the functional expression of secretory/integral membrane protein-encoding lab protein target genes and/or integral membrane protein(s) that interact with the spectrin cytoskeleton to confer epithelial membrane specialization.
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Affiliation(s)
- Jason C Maynard
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
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McMahon LW, Zhang P, Sridharan DM, Lefferts JA, Lambert MW. Knockdown of alphaII spectrin in normal human cells by siRNA leads to chromosomal instability and decreased DNA interstrand cross-link repair. Biochem Biophys Res Commun 2009; 381:288-93. [PMID: 19217883 DOI: 10.1016/j.bbrc.2009.02.038] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Accepted: 02/09/2009] [Indexed: 11/18/2022]
Abstract
Nonerythroid alpha-spectrin (alphaIISp) is a structural protein involved in repair of DNA interstrand cross-links and is deficient in cells from patients with Fanconi anemia (FA), which are defective in ability to repair cross-links. In order to further demonstrate the importance of the role that alphaIISp plays in normal human cells and in the repair defect in FA, alphaIISp was knocked down in normal cells using siRNA. Depletion of alphaIISp in normal cells by siRNA resulted in chromosomal instability and cellular hypersensitivity to DNA interstrand cross-linking agents. An increased number of chromosomal aberrations were observed and, following treatment with a DNA interstrand cross-linking agent, mitomycin C, cells showed decreased cell growth and survival and decreased formation of damage-induced alphaIISp and XPF nuclear foci. Thus depletion of alphaIISp in normal cells leads to a number of defects observed in FA cells, such as chromosome instability and a deficiency in cross-link repair.
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Affiliation(s)
- Laura W McMahon
- Department of Pathology and Laboratory Medicine, UMDNJ-New Jersey Medical School and the Graduate School of Biomedical Sciences, 185 South Orange Avenue, Newark, NJ 07103, USA
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43
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Lynch AM, Hardin J. The assembly and maintenance of epithelial junctions in C. elegans. Front Biosci (Landmark Ed) 2009; 14:1414-32. [PMID: 19273138 DOI: 10.2741/3316] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The epithelial tissues of the C. elegans embryo provide a "minimalist" system for examining phylogenetically conserved proteins that function in epithelial polarity and cell-cell adhesion in a multicellular organism. In this review, we provide an overview of three major molecular complexes at the apical surface of epithelial cells in the C. elegans embryo: the cadherin-catenin complex, the more basal DLG-1/AJM-1 complex, and the apical membrane domain, which shares similarities with the subapical complex in Drosophila and the PAR/aPKC complex in vertebrates. We discuss how the assembly of these complexes contributes to epithelial polarity and adhesion, proteins that act as effectors and/or regulators of each subdomain, and how these complexes functionally interact during embryonic morphogenesis. Although much remains to be clarified, significant progress has been made in recent years to clarify the role of these protein complexes in epithelial morphogenesis, and suggests that C. elegans will continue to be a fruitful system in which to elucidate functional roles for these proteins in a living embryo.
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Affiliation(s)
- Allison M Lynch
- Program in Genetics, University of Wisconsin-Madison, University of Wisconsin-Madison, Department of Zoology, University of Wisconsin-Madison, USA
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Adams MS, Gammill LS, Bronner-Fraser M. Discovery of transcription factors and other candidate regulators of neural crest development. Dev Dyn 2008; 237:1021-33. [PMID: 18351660 DOI: 10.1002/dvdy.21513] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Neural crest cells migrate long distances and form divergent derivatives in vertebrate embryos. Despite previous efforts to identify genes up-regulated in neural crest populations, transcription factors have proved to be elusive due to relatively low expression levels and often transient expression. We screened newly induced neural crest cells for early target genes with the aim of identifying transcriptional regulators and other developmentally important genes. This yielded numerous candidate regulators, including 14 transcription factors, many of which were not previously associated with neural crest development. Quantitative real-time polymerase chain reaction confirmed up-regulation of several transcription factors in newly induced neural crest populations in vitro. In a secondary screen by in situ hybridization, we verified the expression of >100 genes in the neural crest. We note that several of the transcription factors and other genes from the screen are expressed in other migratory cell populations and have been implicated in diverse forms of cancer.
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Affiliation(s)
- Meghan S Adams
- Division of Biology 139-74, California Institute of Technology, Pasadena, California, USA
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45
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Santiago-Martínez E, Soplop NH, Patel R, Kramer SG. Repulsion by Slit and Roundabout prevents Shotgun/E-cadherin-mediated cell adhesion during Drosophila heart tube lumen formation. J Cell Biol 2008; 182:241-8. [PMID: 18663139 PMCID: PMC2483515 DOI: 10.1083/jcb.200804120] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 06/11/2008] [Indexed: 11/22/2022] Open
Abstract
During Drosophila melanogaster heart development, a lumen forms between apical surfaces of contralateral cardioblasts (CBs). We show that Slit and its receptor Roundabout (Robo) are required at CB apical domains for lumen formation. Mislocalization of Slit outside the apical domain causes ectopic lumen formation and the mislocalization of cell junction proteins, E-cadherin (E-Cad) and Enabled, without disrupting overall CB cell polarity. Ectopic lumen formation is suppressed in robo mutants, which indicates robo's requirement for this process. Genetic evidence suggests that Robo and Shotgun (Shg)/E-Cad function together in modulating CB adhesion. robo and shg/E-Cad transheterozygotes have lumen defects. In robo loss-of-function or shg/E-Cad gain-of-function embryos, lumen formation is blocked because of inappropriate CB adhesion and an accumulation of E-Cad at the apical membrane. In contrast, shg/E-Cad loss-of-function or robo gain-of-function blocks lumen formation due to a loss of CB adhesion. Our data show that Slit and Robo pathways function in lumen formation as a repulsive signal to antagonize E-Cad-mediated cell adhesion.
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Affiliation(s)
- Edgardo Santiago-Martínez
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854, USA
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Cotado-Sampayo M, Ramos PO, Perez RO, Ojha M, Barja F. Specificity of commercial anti-spectrin antibody in the study of fungal and Oomycete spectrin: cross-reaction with proteins other than spectrin. Fungal Genet Biol 2008; 45:1008-15. [PMID: 18378170 DOI: 10.1016/j.fgb.2008.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 02/12/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
Spectrin was first described in erythrocytes where it forms a filamentous network in the cytoplasmic face of the plasma membrane and participates in the membrane's structural integrity in addition to controlling the lateral mobility of integral membrane proteins. In fungi, spectrin-like proteins have been described in the plasma membrane, concentrated mainly in the region of maximum apical expansion. This localization led to the idea of a spectrin based membrane skeleton in fungi participating in mechanical integrity of the plasma membrane, generating and maintaining cell polarity. The occurrence of spectrin-like proteins in filamentous fungi, yeasts and Oomycetes, however, is questionable since the presence of such proteins has only been demonstrated with immunochemical methods using antibodies whose specificity is unclear. There is no evidence of a gene coding for the high molecular weight alphabeta-spectrin in the genome of these organisms. Mass spectrometric analysis of the anti alphabeta-spectrin immunoreacting peptides from Neurospora crassa and Phytophthora infestans identified them as elongation factor 2 (NCU07700.4) and Hsp70 (PITG_13237.1), respectively. An attempt was made to correlate the reactivity of anti-spectrin antibody to a common feature of these three proteins i.e., spectrin, elongation factor 2 and heat shock protein 70, in that they all have a hydrophobic region implicated in chaperon activity.
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Affiliation(s)
- Marta Cotado-Sampayo
- Laboratory of Bioenergetics and Microbiology, University of Geneva, ch. des Embrouchis 10, CH 1254 Jussy-Geneva, Switzerland
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Das A, Base C, Manna D, Cho W, Dubreuil RR. Unexpected complexity in the mechanisms that target assembly of the spectrin cytoskeleton. J Biol Chem 2008; 283:12643-53. [PMID: 18287096 DOI: 10.1074/jbc.m800094200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The spectrin cytoskeleton assembles within discrete regions of the plasma membrane in a wide range of animal cell types. Although recent studies carried out in vertebrate systems indicate that spectrin assembly occurs indirectly through the adapter protein ankyrin, recent studies in Drosophila have established that spectrin can also assemble through a direct ankyrin-independent mechanism. Here we tested specific regions of the spectrin molecule for a role in polarized assembly and function. First, we tested mutant beta-spectrins lacking ankyrin binding activity and/or the COOH-terminal pleckstrin homology (PH) domain for their assembly competence in midgut, salivary gland, and larval brain. Remarkably, three different assembly mechanisms operate in these three cell types: 1) neither site was required for assembly in salivary gland; 2) only the PH domain was required in midgut copper cells; and 3) either one of the two sites was sufficient for spectrin assembly in larval brain. Further characterization of the PH domain revealed that it binds strongly to lipid mixtures containing phosphatidylinositol 4,5-bisphosphate (PIP(2)) but not phosphatidylinositol 3,4,5-trisphosphate. A K8Q mutation in the lipid binding region of the PH domain eliminated the PIP(2) interaction in vitro, yet the mutant protein retained full biological function in vivo. Reporter gene studies revealed that PIP(2) and the spectrin PH domain codistribute with one another in cells but not with authentic wild type alphabeta-spectrin. Thus, it appears that the PH domain imparts membrane targeting activity through a second mechanism that takes precedence over its PIP(2) binding activity.
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Affiliation(s)
- Amlan Das
- Laboratory for Molecular Biology and Department of Biological Sciences, University of Illinois, Chicago, Illinois 60607, USA
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Oh Y, Fung LWM. Brain proteins interacting with the tetramerization region of non-erythroid alpha spectrin. Cell Mol Biol Lett 2007; 12:604-20. [PMID: 17607528 PMCID: PMC6275721 DOI: 10.2478/s11658-007-0028-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 06/11/2007] [Indexed: 12/24/2022] Open
Abstract
The N-terminal region of non-erythroid alpha spectrin (SpαII) is responsible for interacting with its binding partner, beta spectrin, to form functional spectrin tetramers. We used a yeast-two-hybrid system, with an N-terminal segment of alpha spectrin representing the functional tetramerization site, as a bait to screen human brain c-DNA library for proteins that interact with the alpha spectrin segment. In addition to several beta spectrin isoforms, we identified 14 proteins that interact with SpαII. Seven of the 14 were matched to 6 known proteins: Duo protein, Lysyl-tRNA synthetase, TBP associated factor 1, two isoforms (b and c) of a protein kinase A interacting protein and Zinc finger protein 333 (2 different segments). Four of the 6 proteins are located primarily in the nucleus, suggesting that spectrin plays important roles in nuclear functions. The remaining 7 proteins were unknown to the protein data base. Structural predictions show that many of the 14 proteins consist of a large portion of unstructured regions, suggesting that many of these proteins fold into a rather flexible conformation. It is interesting to note that all but 3 of the 14 proteins are predicted to consist of one to four coiled coils (amphiphilic helices). A mutation in SpαII, V22D, which interferes with the coiled coil bundling of SpαII with beta spectrin, also affects SpαII interaction with Duo protein, TBP associated factor 1 and Lysyl-tRNA synthetase, suggesting that they may compete with beta spectrin for interaction with SpαII. Future structural and functional studies of these proteins to provide interaction mechanisms will no doubt lead to a better understanding of brain physiology and pathophysiology.
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Affiliation(s)
- Younsang Oh
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, MC 111, Chicago, IL 60607 USA
| | - Leslie W. -M. Fung
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, MC 111, Chicago, IL 60607 USA
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Meary F, Metral S, Ferreira C, Eladari D, Colin Y, Lecomte MC, Nicolas G. A mutant alphaII-spectrin designed to resist calpain and caspase cleavage questions the functional importance of this process in vivo. J Biol Chem 2007; 282:14226-37. [PMID: 17374614 DOI: 10.1074/jbc.m700028200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
alpha- and beta-spectrins are components of molecular scaffolds located under the lipid bilayer and named membrane skeletons. Disruption of these scaffolds through mutations in spectrins demonstrated that they are involved in the membrane localization or the maintenance of proteins associated with them. The ubiquitous alphaII-spectrin chain bears in its central region a unique domain that is sensitive to several proteases such as calpains or caspases. The conservation of this region in vertebrates suggests that the proteolysis of alphaII-spectrin by these enzymes could be involved in important functions. To assess the role of alphaII-spectrin cleavage in vivo, we generated a murine model in which the exons encoding the region defining this cleavage sensitivity were disrupted by gene targeting. Surprisingly, homozygous mice expressing this mutant alphaII-spectrin appeared healthy, bred normally, and had no histological anomaly. Remarkably, the mutant alphaII-spectrin assembles correctly into the membrane skeleton, thus challenging the notion that this region is required for the stable biogenesis of the membrane skeleton in nonerythroid cells. Our finding also argues against a critical role of this particular alphaII-spectrin cleavage in either major cellular functions or in normal development.
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Hülsmeier J, Pielage J, Rickert C, Technau GM, Klämbt C, Stork T. Distinct functions of alpha-Spectrin and beta-Spectrin during axonal pathfinding. Development 2007; 134:713-22. [PMID: 17215305 DOI: 10.1242/dev.02758] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cell-shape changes during development require a precise coupling of the cytoskeleton with proteins situated in the plasma membrane. Important elements controlling the shape of cells are the Spectrin proteins that are expressed as a subcortical cytoskeletal meshwork linking specific membrane receptors with F-actin fibers. Here, we demonstrate that Drosophila karussell mutations affect beta-spectrin and lead to distinct axonal patterning defects in the embryonic CNS. karussell mutants display a slit-sensitive axonal phenotype characterized by axonal looping in stage-13 embryos. Further analyses of individual, labeled neuroblast lineages revealed abnormally structured growth cones in these animals. Cell-type-specific rescue experiments demonstrate that beta-Spectrin is required autonomously and non-autonomously in cortical neurons to allow normal axonal patterning. Within the cell, beta-Spectrin is associated with alpha-Spectrin. We show that expression of the two genes is tightly regulated by post-translational mechanisms. Loss of beta-Spectrin significantly reduces levels of neuronal alpha-Spectrin expression, whereas gain of beta-Spectrin leads to an increase in alpha-Spectrin protein expression. Because the loss of alpha-spectrin does not result in an embryonic nervous system phenotype, beta-Spectrin appears to act at least partially independent of alpha-Spectrin to control axonal patterning.
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Affiliation(s)
- Jörn Hülsmeier
- Institut für Neurobiologie, Badestr. 9, 48149 Münster, Germany
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