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Demers EG, Stajich JE, Ashare A, Occhipinti P, Hogan DA. Balancing Positive and Negative Selection: In Vivo Evolution of Candida lusitaniae MRR1. mBio 2021; 12:e03328-20. [PMID: 33785623 PMCID: PMC8092287 DOI: 10.1128/mbio.03328-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
The evolution of pathogens in response to selective pressures present during chronic infections can influence their persistence and virulence and the outcomes of antimicrobial therapy. Because subpopulations within an infection can be spatially separated and the host environment can fluctuate, an appreciation of the pathways under selection may be most easily revealed through the analysis of numerous isolates from single infections. Here, we continued our analysis of a set of clonally derived Clavispora (Candida) lusitaniae isolates from a single chronic lung infection with a striking enrichment in the number of alleles of MRR1 Genetic and genomic analyses found evidence for repeated acquisition of gain-of-function mutations that conferred constitutive Mrr1 activity. In the same population, there were multiple alleles with both gain-of-function mutations and secondary suppressor mutations that either attenuated or abolished the constitutive activity, suggesting the presence of counteracting selective pressures. Our studies demonstrated trade-offs between high Mrr1 activity, which confers resistance to the antifungal fluconazole, host factors, and bacterial products through its regulation of MDR1, and resistance to hydrogen peroxide, a reactive oxygen species produced in the neutrophilic environment associated with this infection. This inverse correlation between high Mrr1 activity and hydrogen peroxide resistance was observed in multiple Candida species and in serially collected populations from this individual over 3 years. These data lead us to propose that dynamic or variable selective pressures can be reflected in population genomics and that these dynamics can complicate the drug resistance profile of the population.IMPORTANCE Understanding microbial evolution within patients is critical for managing chronic infections and understanding host-pathogen interactions. Here, our analysis of multiple MRR1 alleles in isolates from a single Clavispora (Candida) lusitaniae infection revealed the selection for both high and low Mrr1 activity. Our studies reveal trade-offs between high Mrr1 activity, which confers resistance to the commonly used antifungal fluconazole, host antimicrobial peptides, and bacterial products, and resistance to hydrogen peroxide. This work suggests that spatial or temporal differences within chronic infections can support a large amount of dynamic and parallel evolution and that Mrr1 activity is under both positive and negative selective pressure to balance different traits that are important for microbial survival.
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Affiliation(s)
- Elora G Demers
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jason E Stajich
- Department of Microbiology & Plant Pathology and Institute for Integrative Genome Biology, University of California-Riverside, Riverside, California, USA
| | - Alix Ashare
- Dartmouth-Hitchcock Medical Center, Section of Pulmonary and Critical Care Medicine, Lebanon, New Hampshire, USA
| | - Patricia Occhipinti
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Deborah A Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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2
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Radaelli F, Paggi S, Repici A, Gullotti G, Cesaro P, Rotondano G, Cugia L, Trovato C, Spada C, Fuccio L, Occhipinti P, Pace F, Fabbri C, Buda A, Manes G, Feliciangeli G, Manno M, Barresi L, Anderloni A, Dulbecco P, Rogai F, Amato A, Senore C, Hassan C. Barriers against split-dose bowel preparation for colonoscopy. Gut 2017; 66:1428-1433. [PMID: 27196589 DOI: 10.1136/gutjnl-2015-311049] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 03/14/2016] [Accepted: 03/19/2016] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Although split regimen is associated with higher adenoma detection and is recommended for elective colonoscopy, its adoption remains suboptimal. The identification of patient-related barriers may improve its implementation. Our aim was to assess patients' attitude towards split regimen and patient-related factors associated with its uptake. DESIGN In a multicentre, prospective study, outpatients undergoing colonoscopy from 8:00 to 14:00 were given written instructions for 4 L polyethylene glycol bowel preparation, offering the choice between split-dose and day-before regimens and emphasising the superiority of split regimen on colonoscopy outcomes. Uptake of split regimen and association with patient-related factors were explored by a 20-item questionnaire. RESULTS Of the 1447 patients (mean age 59.2±13.5 years, men 54.3%), 61.7% and 38.3% chose a split-dose and day-before regimens, respectively. A linear correlation was observed between time of colonoscopy appointments and split-dose uptake, from 27.3% in 8:00 patients to 96% in 14:00 patients (p<0.001, χ2 for linear trend). At multivariate analysis, colonoscopy appointment before 10:00 (OR 0.14, 95% CI 0.11 to 0.18), travel time to endoscopy service >1 h (OR 0.55, 95% CI 0.38 to 0.79), low education level (OR 0.72, 95% CI 0.54 to 0.96) and female gender (OR 0.74, 95% CI 0.58 to 0.95) were inversely correlated with the uptake of split-dose. Overall, the risk of travel interruption and faecal incontinence was slightly increased in split regimen patients (3.0% vs 1.4% and 1.5% vs 0.9%, respectively; p=NS). Split regimen was an independent predictor of adequate colon cleansing (OR 3.34, 95% CI 2.40 to 4.63) and polyp detection (OR 1.46, 95% CI 1.11 to 1.92). CONCLUSION Patient attitude towards split regimen is suboptimal, especially for early morning examinations. Interventions to improve patient compliance (ie, policies to reorganise colonoscopy timetable, educational initiatives for patient and healthcare providers) should be considered. TRIAL REGISTRATION NUMBER NCT02287051; pre-result.
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Affiliation(s)
- F Radaelli
- Department of Gastroenterology, Valduce Hospital, Como, Italy
| | - S Paggi
- Department of Gastroenterology, Valduce Hospital, Como, Italy
| | - A Repici
- Humanitas Research Hospital, Humanitas University, Rozzano, Milan, Italy
| | | | - P Cesaro
- Poliambulanza Foundation Hospital, Brescia, Italy
| | - G Rotondano
- Maresca Hospital, ASLNA3sud, Torre del Greco, Naples, Italy
| | - L Cugia
- SS Annunziata Hospital, Sassari, Italy
| | - C Trovato
- European Institute of Oncology, Milan, Italy
| | - C Spada
- Fondazione Policlinico Universitario Agostino Gemelli, Rome, Italy
| | - L Fuccio
- S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | | | - F Pace
- Bolognini Hospital, Seriate, Italy
| | - C Fabbri
- Bellaria-Maggiore Hospital, Bologna, Italy
| | - A Buda
- S. Maria del Prato Hospital, Feltre, Italy
| | - G Manes
- G. Salvini Hospital, Garbagnate Milanese, Milan, Italy
| | | | - M Manno
- Ospedali di Carpi e Mirandola, Modena, Italy
| | - L Barresi
- IRCCS-ISMETT (Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione), Palermo, Italy
| | - A Anderloni
- Humanitas Research Hospital, Humanitas University, Rozzano, Milan, Italy
| | | | - F Rogai
- University Hospital Careggi, Florence, Italy
| | - A Amato
- Department of Gastroenterology, Valduce Hospital, Como, Italy
| | - C Senore
- Centro di Prevenzione Oncologica (CPO Piemonte), AOU Città della Salute e della Scienza, Turin, Italy
| | - C Hassan
- Nuovo Regina Margherita Hospital, Rome, Italy
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3
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Dundon SER, Chang SS, Kumar A, Occhipinti P, Shroff H, Roper M, Gladfelter AS. Clustered nuclei maintain autonomy and nucleocytoplasmic ratio control in a syncytium. Mol Biol Cell 2016; 27:2000-7. [PMID: 27193301 PMCID: PMC4927274 DOI: 10.1091/mbc.e16-02-0129] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/09/2016] [Indexed: 01/14/2023] Open
Abstract
Nuclei in syncytia found in fungi, muscles, and tumors can behave independently despite cytoplasmic translation and the homogenizing potential of diffusion. We use a dynactin mutant strain of the multinucleate fungus Ashbya gossypii with highly clustered nuclei to assess the relative contributions of nucleus and cytoplasm to nuclear autonomy. Remarkably, clustered nuclei maintain cell cycle and transcriptional autonomy; therefore some sources of nuclear independence function even with minimal cytosol insulating nuclei. In both nuclear clusters and among evenly spaced nuclei, a nucleus' transcriptional activity dictates local cytoplasmic contents, as assessed by the localization of several cyclin mRNAs. Thus nuclear activity is a central determinant of the local cytoplasm in syncytia. Of note, we found that the number of nuclei per unit cytoplasm was identical in the mutant to that in wild-type cells, despite clustered nuclei. This work demonstrates that nuclei maintain autonomy at a submicrometer scale and simultaneously maintain a normal nucleocytoplasmic ratio across a syncytium up to the centimeter scale.
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Affiliation(s)
| | - Shyr-Shea Chang
- Departments of Mathematics and Biomathematics, University of California, Los Angeles, Los Angeles, CA 90095
| | - Abhishek Kumar
- Section on High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
| | | | - Hari Shroff
- Section on High Resolution Optical Imaging, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
| | - Marcus Roper
- Departments of Mathematics and Biomathematics, University of California, Los Angeles, Los Angeles, CA 90095
| | - Amy S Gladfelter
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 The Bell Center, Marine Biological Laboratory, Woods Hole, MA 02543
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4
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Bridges AA, Jentzsch MS, Oakes PW, Occhipinti P, Gladfelter AS. Micron-scale plasma membrane curvature is recognized by the septin cytoskeleton. J Cell Biol 2016; 213:23-32. [PMID: 27044896 PMCID: PMC4828694 DOI: 10.1083/jcb.201512029] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 02/23/2016] [Indexed: 11/22/2022] Open
Abstract
Fungal and human septins can distinguish between different degrees of micron-scale curvature in cells, suggesting that this property of the septin cytoskeleton provides a cell with a mechanism to sense its local shape. Cells change shape in response to diverse environmental and developmental conditions, creating topologies with micron-scale features. Although individual proteins can sense nanometer-scale membrane curvature, it is unclear if a cell could also use nanometer-scale components to sense micron-scale contours, such as the cytokinetic furrow and base of neuronal branches. Septins are filament-forming proteins that serve as signaling platforms and are frequently associated with areas of the plasma membrane where there is micron-scale curvature, including the cytokinetic furrow and the base of cell protrusions. We report here that fungal and human septins are able to distinguish between different degrees of micron-scale curvature in cells. By preparing supported lipid bilayers on beads of different curvature, we reconstitute and measure the intrinsic septin curvature preference. We conclude that micron-scale curvature recognition is a fundamental property of the septin cytoskeleton that provides the cell with a mechanism to know its local shape.
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Affiliation(s)
- Andrew A Bridges
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 The Bell Center, Marine Biological Laboratory, Woods Hole, MA 02543
| | | | - Patrick W Oakes
- Department of Physics, Institute for Biophysical Dynamics and James Franck Institute, University of Chicago, Chicago, IL 60637
| | | | - Amy S Gladfelter
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755 The Bell Center, Marine Biological Laboratory, Woods Hole, MA 02543
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5
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Zhang H, Elbaum-Garfinkle S, Langdon EM, Taylor N, Occhipinti P, Bridges AA, Brangwynne CP, Gladfelter AS. RNA Controls PolyQ Protein Phase Transitions. Mol Cell 2016; 60:220-30. [PMID: 26474065 DOI: 10.1016/j.molcel.2015.09.017] [Citation(s) in RCA: 480] [Impact Index Per Article: 60.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/09/2015] [Accepted: 09/17/2015] [Indexed: 12/28/2022]
Abstract
Compartmentalization in cells is central to the spatial and temporal control of biochemistry. In addition to membrane-bound organelles, membrane-less compartments form partitions in cells. Increasing evidence suggests that these compartments assemble through liquid-liquid phase separation. However, the spatiotemporal control of their assembly, and how they maintain distinct functional and physical identities, is poorly understood. We have previously shown an RNA-binding protein with a polyQ-expansion called Whi3 is essential for the spatial patterning of cyclin and formin transcripts in cytosol. Here, we show that specific mRNAs that are known physiological targets of Whi3 drive phase separation. mRNA can alter the viscosity of droplets, their propensity to fuse, and the exchange rates of components with bulk solution. Different mRNAs impart distinct biophysical properties of droplets, indicating mRNA can bring individuality to assemblies. Our findings suggest that mRNAs can encode not only genetic information but also the biophysical properties of phase-separated compartments.
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Affiliation(s)
- Huaiying Zhang
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA; Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Shana Elbaum-Garfinkle
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Erin M Langdon
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Nicole Taylor
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Patricia Occhipinti
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Andrew A Bridges
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Clifford P Brangwynne
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
| | - Amy S Gladfelter
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
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6
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Kaplan C, Jing B, Winterflood CM, Bridges AA, Occhipinti P, Schmied J, Grinhagens S, Gronemeyer T, Tinnefeld P, Gladfelter AS, Ries J, Ewers H. Absolute Arrangement of Subunits in Cytoskeletal Septin Filaments in Cells Measured by Fluorescence Microscopy. Nano Lett 2015; 15:3859-3864. [PMID: 25939363 DOI: 10.1021/acs.nanolett.5b00693] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We resolved the organization of subunits in cytoskeletal polymers in cells by light microscopy. Septin GTPases form linear complexes of about 32 nm length that polymerize into filaments. We visualized both termini of septin complexes by single molecule microscopy in vitro. Complexes appeared as 32 nm spaced localization pairs, and filaments appeared as stretches of equidistant localizations. Cellular septins were resolved as localization pairs and thin stretches of equidistant localizations.
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Affiliation(s)
- Charlotte Kaplan
- †Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Bo Jing
- †Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
| | | | - Andrew A Bridges
- ‡Life Science Center, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Patricia Occhipinti
- ‡Life Science Center, Dartmouth College, Hanover, New Hampshire 03755, United States
| | | | - Sören Grinhagens
- ∥Institute of Molecular Genetics and Cell Biology, University of Ulm, 89081 Ulm, Germany
| | - Thomas Gronemeyer
- ∥Institute of Molecular Genetics and Cell Biology, University of Ulm, 89081 Ulm, Germany
| | | | - Amy S Gladfelter
- ‡Life Science Center, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Jonas Ries
- †Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
| | - Helge Ewers
- †Institute of Biochemistry, ETH Zurich, 8093 Zurich, Switzerland
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7
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Abstract
Transcripts encoding polarity factors such as Bni1 and Spa2 are nonrandomly clustered in the cytosol to initiate and maintain sites of polarized growth in the fungus Ashbya gossypii. Dendritic growth in fungi and neurons requires that multiple axes of polarity are established and maintained within the same cytoplasm. We have discovered that transcripts encoding key polarity factors including a formin, Bni1, and a polarisome scaffold, Spa2, are nonrandomly clustered in the cytosol to initiate and maintain sites of polarized growth in the fungus Ashbya gossypii. This asymmetric distribution requires the mRNAs to interact with a polyQ-containing protein, Whi3, and a Pumilio protein with a low-complexity sequence, Puf2. Cells lacking Whi3 or Puf2 had severe defects in establishing new sites of polarity and failed to localize Bni1 protein. Interaction of mRNAs with Whi3 and Puf2 promotes enrichment of transcripts at established sites of polarized growth and clustering of polarity transcripts throughout the cell body. Thus, aggregation-prone proteins make functional assemblies to position polarity transcripts, and nonrandom positioning of transcripts is required for symmetry-breaking events. This reveals a physiological function for polyQ-driven assemblies in regulating cell polarity.
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Affiliation(s)
- ChangHwan Lee
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
| | | | - Amy S Gladfelter
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755
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8
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Mehta SB, McQuilken M, Occhipinti P, Verma A, Oldenbourg R, Gladfelter AS, Tani T. Dynamics of Polymeric Protein Assemblies in Live Cells Revealed by Fluorescence Polarization Imaging of Single Molecules. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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9
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Lee C, Zhang H, Baker AE, Occhipinti P, Borsuk ME, Gladfelter AS. Protein aggregation behavior regulates cyclin transcript localization and cell-cycle control. Dev Cell 2013; 25:572-84. [PMID: 23769973 DOI: 10.1016/j.devcel.2013.05.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 01/28/2013] [Accepted: 05/07/2013] [Indexed: 12/26/2022]
Abstract
Little is known about the active positioning of transcripts outside of embryogenesis or highly polarized cells. We show here that a specific G1 cyclin transcript is highly clustered in the cytoplasm of large multinucleate cells. This heterogeneous cyclin transcript localization results from aggregation of an RNA-binding protein, and deletion of a polyglutamine stretch in this protein results in random transcript localization. These multinucleate cells are remarkable in that nuclei cycle asynchronously despite sharing a common cytoplasm. Notably, randomization of cyclin transcript localization significantly diminishes nucleus-to-nucleus differences in the number of mRNAs and synchronizes cell-cycle timing. Thus, nonrandom cyclin transcript localization is important for cell-cycle timing control and arises due to polyQ-dependent behavior of an RNA-binding protein. There is a widespread association between polyQ expansions and RNA-binding motifs, suggesting that this is a broadly exploited mechanism to produce spatially variable transcripts and heterogeneous cell behaviors. PAPERCLIP:
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Affiliation(s)
- Changhwan Lee
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
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10
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Tani T, Mehta S, DeMay BS, Occhipinti P, Oldenbourg R, Gladfelter AS. Fluorescent Single Molecule Orientation Imaging for Exploring 3D Architectural Dynamics of Cytoskeletal Protein Assembly in Living Cells. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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11
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DeMay BS, Bai X, Howard L, Occhipinti P, Meseroll RA, Spiliotis ET, Oldenbourg R, Gladfelter AS. Septin filaments exhibit a dynamic, paired organization that is conserved from yeast to mammals. ACTA ACUST UNITED AC 2011; 193:1065-81. [PMID: 21670216 PMCID: PMC3115802 DOI: 10.1083/jcb.201012143] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Polarized fluorescence microscopy reveals that septins across diverse species assemble into similar higher-order structures consisting of dynamic, paired filaments. The septins are conserved, GTP-binding proteins important for cytokinesis, membrane compartmentalization, and exocytosis. However, it is unknown how septins are arranged within higher-order structures in cells. To determine the organization of septins in live cells, we developed a polarized fluorescence microscopy system to monitor the orientation of GFP dipole moments with high spatial and temporal resolution. When GFP was fused to septins, the arrangement of GFP dipoles reflected the underlying septin organization. We demonstrated in a filamentous fungus, a budding yeast, and a mammalian epithelial cell line that septin proteins were organized in an identical highly ordered fashion. Fluorescence anisotropy measurements indicated that septin filaments organized into pairs within live cells, just as has been observed in vitro. Additional support for the formation of pairs came from the observation of paired filaments at the cortex of cells using electron microscopy. Furthermore, we found that highly ordered septin structures exchanged subunits and rapidly rearranged. We conclude that septins assemble into dynamic, paired filaments in vivo and that this organization is conserved from yeast to mammals.
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Affiliation(s)
- Bradley S DeMay
- Department of Biological Sciences and 2 EM Facility, Dartmouth College, Hanover, NH 03755, USA
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12
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DeMay BS, Meseroll RA, Occhipinti P, Gladfelter AS. Cellular requirements for the small molecule forchlorfenuron to stabilize the septin cytoskeleton. Cytoskeleton (Hoboken) 2010; 67:383-99. [PMID: 20517926 DOI: 10.1002/cm.20452] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The septins are filament-forming, GTP-binding proteins that are conserved from yeast to humans. Septins assemble into higher-order structures such as rings, bars, and gauzes with diverse functions including serving as membrane diffusion barriers and scaffolds for cell signaling. The basis for septin filament polymerization and the rules governing septin polymer dynamics are presently not well understood. Pharmacological agents are essential tools in studying such properties of the actin and microtubule cytoskeletons however there are only limited reports of a drug specific to the septin cytoskeleton. Forchlorfenuron (FCF) is a synthetic plant cytokinin used in agriculture which has been shown to alter septin organization in yeast and mammalian tissue culture cells. Here we assess cellular requirements and properties of septin-based structures induced by FCF. Treatment of the filamentous fungus Ashbya gossypii with FCF leads to assembly of extensive septin fibers throughout hyphae which is rapidly reversed upon removal of the drug. These fibers do not exchange or add septin subunits after assembly, indicating that FCF suppresses normal septin dynamics and stabilizes the polymers. While FCF-induced septin fibers do not co-localize to actin or microtubules, a polarized F-actin cytoskeleton is likely required for the assembly of drug-induced septin fibers. Thus, FCF is a potent inducer of septin polymerization and acts as a reversible stabilizer of extended septin polymers. This drug will be a powerful tool for studying mechanisms of septin polymerization and function, particularly in cell types where molecular analyses are complicated by the presence of multiple isoforms and limited genetics.
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Affiliation(s)
- Bradley S DeMay
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
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13
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Nair DR, D'Ausilio CA, Occhipinti P, Borsuk ME, Gladfelter AS. A conserved G₁ regulatory circuit promotes asynchronous behavior of nuclei sharing a common cytoplasm. Cell Cycle 2010; 9:3771-9. [PMID: 20930528 DOI: 10.4161/cc.9.18.12999] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Synthesis and accumulation of conserved cell cycle regulators such as cyclins are thought to promote G₁/S and G₂/M transitions in most eukaryotes. When cells at different stages of the cell cycle are fused to form heterokaryons, the shared complement of regulators in the cytoplasm induces the nuclei to become synchronized. However, multinucleate fungi often display asynchronous nuclear division cycles, even though the nuclei inhabit a shared cytoplasm. Similarly, checkpoints can induce nuclear asynchrony in multinucleate cells by arresting only the nucleus that receives damage. The cell biological basis for nuclear autonomy in a common cytoplasm is not known. Here we show that in the filamentous fungus Ashbya gossypii, sister nuclei born from one mitosis immediately lose synchrony in the subsequent G₁ interval. A conserved G₁ transcriptional regulatory circuit involving the Rb-analogue Whi5p promotes the asynchronous behavior yet Whi5 protein is uniformly distributed among nuclei throughout the cell cycle. The homologous Whi5p circuit in S. cerevisiae employs positive feedback to promote robust and coherent entry into the cell cycle. We propose that positive feedback in this same circuit generates timing variability in a multinucleate cell. These unexpected findings indicate that a regulatory program whose products (mRNA transcripts) are translated in a common cytoplasm can nevertheless promote variability in the individual behavior of sister nuclei.
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14
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DeMay BS, Meseroll RA, Occhipinti P, Gladfelter AS. Regulation of distinct septin rings in a single cell by Elm1p and Gin4p kinases. Mol Biol Cell 2009; 20:2311-26. [PMID: 19225152 DOI: 10.1091/mbc.e08-12-1169] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Septins are conserved, GTP-binding proteins that assemble into higher order structures, including filaments and rings with varied cellular functions. Using four-dimensional quantitative fluorescence microscopy of Ashbya gossypii fungal cells, we show that septins can assemble into morphologically distinct classes of rings that vary in dimensions, intensities, and positions within a single cell. Notably, these different classes coexist and persist for extended times, similar in appearance and behavior to septins in mammalian neurons and cultured cells. We demonstrate that new septin proteins can add through time to assembled rings, indicating that septins may continue to polymerize during ring maturation. Different classes of rings do not arise from the presence or absence of specific septin subunits and ring maintenance does not require the actin and microtubule cytoskeletons. Instead, morphological and behavioral differences in the rings require the Elm1p and Gin4p kinases. This work demonstrates that distinct higher order septin structures form within one cell because of the action of specific kinases.
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Affiliation(s)
- Bradley S DeMay
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
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15
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Ruzza M, Andorno S, Ballarè M, Brondolo R, Cusumano S, D'Andrea F, La Terra G, Occhipinti P, Picchini G, Sartori M. [A sustained response in chronic hepatitis C treated with interferon]. Recenti Prog Med 1994; 85:433-7. [PMID: 7938875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We analyzed 27 subjects with long-term response, from a group of 110 interferon treated patients with biopsy-proven chronic hepatitis and serum anti-HCV antibodies. The following variables were assessed as potential predictors: sex, age, ALT level before the therapy was started, liver structure, type of interferon, total amount of interferon. Total amount of administered interferon statistically correlated with long-term response by univariate analysis. Nevertheless upon stepwise logistic multivariate analysis none of them was independently predictive of long-term response. Additional studies would be needed in order to develop a model capable of predicting from pre-treatment features which patients are likely to have long-term response.
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Affiliation(s)
- M Ruzza
- Clinica Medica Generale, Dipartimento di Scienze Biomediche ed Oncologia Umana, Università, Novara
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16
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Affiliation(s)
- M Del Piano
- Gastrointestinal Endoscopy Unit, Ospedale Maggiore di Novara, Italy
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17
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Del Piano M, Manfredda I, Montino F, Occhipinti P. [Comparison of 3 methods of preparation for colonoscopy]. MINERVA GASTROENTERO 1993; 39:89-92. [PMID: 8364106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We compared three cleansing methods of preparation for colonoscopy in 150 patients: the first containing a mixture of cathartics, especially sennosides: the second containing polyethyleneglycol: the third containing a mixture of monosodic monohydrated and bisodic heptahydrated phosphate. We evaluated the tolerability, the compliance and the side effects of the preparations. Regarding the evaluated parameters, it was found that the mixture of monosodic and bisodic heptahydrated phosphate was more valid than the other preparations.
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Affiliation(s)
- M Del Piano
- II Divisione di Medicina Generale, Ospedale Maggiore della Carità di Novara
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18
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19
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Boccardi A, Spalluto F, Del Piano M, Occhipinti P, Montino F, Bergamaschi V. [A gastric leiomyoma of conspicuous size. A case report]. Minerva Dietol Gastroenterol 1990; 36:119-21. [PMID: 2247259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The authors describe a large gastric leiomyoma with prevailing subserous growth. Conventional X-ray examination and endoscopy failed to diagnose the lesion properly. On the contrary, with CT it was possible to hypothesize the existence of leiomyoma with the correct definition of the outline of the lesion.
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Affiliation(s)
- A Boccardi
- Servizio di Radiodiagnostica, Ospedale Maggiore della Carità, Novara
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20
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Brunero M, Graziano L, Di Mattia O, Arceci F, Occhipinti P. [Neoplasms of the duodenum. A description of 2 clinical cases]. MINERVA CHIR 1989; 44:1385-8. [PMID: 2761741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Duodenal tumours are a rare pathology, hard to diagnose early because of the unsubstantial symptomatology even though, in recent years, with the advent of improved techniques, a larger number have found their way into the literature. Two cases of duodenal cancer, one an adenocarcinoma localised in the first portion of the duodenum and one a subpapillary leiomyosarcoma are reported. 2 and 5 years respectively after the operation, both patients are in good health and do not present signs of disease.
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21
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Cardano S, D'Andrea F, Occhipinti P. [A case of fibro-lamellar carcinoma of the liver]. G Clin Med 1988; 69:439-41. [PMID: 2854085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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22
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Del Piano M, Montino F, Occhipinti P, Rossi F, Maffei S, Rudoni M. [Scintigraphy using labelled sucralfate in the diagnosis of chronic idiopathic inflammatory diseases of the intestine]. Ann Ital Med Int 1988; 3:126-31. [PMID: 3152843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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23
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Campanini M, Saglietti G, Zaccala G, Occhipinti P, Cardano S, Monteverde A. [Behavior of thyroid hormones in chronic hepatopathies]. Recenti Prog Med 1986; 77:405-10. [PMID: 3797791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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