ARKOWITZ

Robert ARKOWITZ

Polarized growth in yeast

Main interests

  • Transduction of external stimuli into asymmetric growth that is tightly controlled in time and space
  • Coordination and regulation of membrane traffic resulting in distinct cell shape changes
  • Temporal and spatial regulation of forces involved in invasive growth
  • Interplay between force generation, cell polarity/cell organization and membrane traffic

Scientific Questions

Our main interest is how cells spatially and temporally regulate growth. Polarized growth is essential for both internal organization and generation of complex multi-cellular structures. Asymmetric growth requires the specification of a polarity site, orientation of the cytoskeleton towards this site and subsequent directed membrane traffic. Our primary focus is on polarized growth, morphogenesis and development in response to external cues, predominantly in the human pathogenic yeast Candida albicans but also in the baker’s yeast Saccharomyces cerevisiae. The human commensal C. albicans switches from an oval yeast form to a hyphal filamentous form that can invade tissue and evade host immune cells. This dimorphic switch is critical for pathogenicity of C. albicans, which is a major cause of life-threatening nosocomial infections as well as persistent mucosal infections. We are investigating the roles of polarity, membrane traffic and mechanical forces in this human fungal pathogen.

Our Strategy

We take advantage of a range of genetic and chemical perturbations to probe cell polarity, membrane traffic and invasive growth in C. albicans. Molecular genetic approaches are used to generate mutants and fluorescent reporter fusions. A variety of microscopy techniques are used to probe the dynamics of cell polarity, membrane traffic and invasive growth with high temporal and spatial resolution. An assortment of reporters for lipid and active small GTPase distribution are optimized and used to follow establishment and maintenance of cellular asymmetries in vivo. In addition, micro-fabrication approaches are used to impose and vary physical constraints in these studies. We also work in close collaboration physicists to model aspects of cell polarity, membrane traffic and invasive growth in order to predict key parameters in these processes that will be subsequently tested.

Research Aims

Polarity

  • Role of GTPases and lipids in initiation and maintenance of asymmetric growth.
  • Cellular reorganization upon cell shape changes.
  • Importance of cell polarity in multicellular structures.
  • Regulation of cell polarity upon external stimuli or changes in the environment, including host cells.
  • Role of cell polarity in force generation and regulation of membrane traffic.

Membrane traffic

  • Regulation of membrane traffic during yeast to hyphal transition.
  • Membrane traffic dynamics during invasion and infection.
  • Coordination of membrane traffic in multicellular structures.
  • Traffic and transport of membrane lipids and their importance in hyphal growth.
  • Local control of membrane traffic for site-specific growth and cell shape changes.

Forces

  • Forces critical for invasive growth.
  • Effect of resistive forces on cellular organization and polarity.
  • Role of local alterations or perturbations of resistive and cellular forces during substrate penetration and invasion.
  • Importance of membrane traffic and cell wall for invasive growth.
  • Cellular forces and interplay with resistive forces during different types of infection.
Researchers

BASSILANA Martine - +33 489150740
FOLLETTE Peter - +33 489150741

Postdocs

GARCIA RODAS Rocio - +33 489150741

PreDocs

BASANTE BEDOYA Miguel Angel - +33 489150741

Engineers & Technicians

BOGLIOLO Stéphanie - +33 489150741

Masters

WANG Xin - +33 R

 

Recent publications

  1. Etienne-Manneville, S, Arkowitz, R. Cell polarity inside-out. Curr. Opin. Cell Biol. 2020;62 :iii-iv. doi: 10.1016/j.ceb.2020.01.008. PubMed PMID:32081296 .
  2. Bassilana, M, Puerner, C, Arkowitz, RA. External signal-mediated polarized growth in fungi. Curr. Opin. Cell Biol. 2020;62 :150-158. doi: 10.1016/j.ceb.2019.11.001. PubMed PMID:31875532 .
  3. Silva, PM, Puerner, C, Seminara, A, Bassilana, M, Arkowitz, RA. Secretory Vesicle Clustering in Fungal Filamentous Cells Does Not Require Directional Growth. Cell Rep. 2019;28 (8):2231-2245.e5. doi: 10.1016/j.celrep.2019.07.062. PubMed PMID:31433995 .
  4. Arkowitz, RA, Bassilana, M. Recent advances in understanding Candida albicans hyphal growth. F1000Res. 2019;8 :. doi: 10.12688/f1000research.18546.1. PubMed PMID:31131089 PubMed Central PMC6530606.
  5. Weiner, A, Orange, F, Lacas-Gervais, S, Rechav, K, Ghugtyal, V, Bassilana, M et al.. On-site secretory vesicle delivery drives filamentous growth in the fungal pathogen Candida albicans. Cell. Microbiol. 2019;21 (1):e12963. doi: 10.1111/cmi.12963. PubMed PMID:30321912 .
  6. Bar-Yosef, H, Gildor, T, Ramírez-Zavala, B, Schmauch, C, Weissman, Z, Pinsky, M et al.. A Global Analysis of Kinase Function in Candida albicans Hyphal Morphogenesis Reveals a Role for the Endocytosis Regulator Akl1. Front Cell Infect Microbiol. 2018;8 :17. doi: 10.3389/fcimb.2018.00017. PubMed PMID:29473018 PubMed Central PMC5809406.
  7. Wakade, R, Labbaoui, H, Stalder, D, Arkowitz, RA, Bassilana, M. Overexpression of YPT6 restores invasive filamentous growth and secretory vesicle clustering in a Candida albicans arl1 mutant. Small GTPases. 2020;11 (3):204-210. doi: 10.1080/21541248.2017.1378157. PubMed PMID:28960163 .
  8. Labbaoui, H, Bogliolo, S, Ghugtyal, V, Solis, NV, Filler, SG, Arkowitz, RA et al.. Role of Arf GTPases in fungal morphogenesis and virulence. PLoS Pathog. 2017;13 (2):e1006205. doi: 10.1371/journal.ppat.1006205. PubMed PMID:28192532 PubMed Central PMC5325608.
  9. Lin, TC, Neuner, A, Flemming, D, Liu, P, Chinen, T, Jäkle, U et al.. MOZART1 and γ-tubulin complex receptors are both required to turn γ-TuSC into an active microtubule nucleation template. J. Cell Biol. 2016;215 (6):823-840. doi: 10.1083/jcb.201606092. PubMed PMID:27920216 PubMed Central PMC5166503.
  10. Stone, DE, Arkowitz, RA. In Situ Assays of Chemotropism During Yeast Mating. Methods Mol. Biol. 2016;1407 :1-12. doi: 10.1007/978-1-4939-3480-5_1. PubMed PMID:27271890 .
  11. Ismael, A, Tian, W, Waszczak, N, Wang, X, Cao, Y, Suchkov, D et al.. Gβ promotes pheromone receptor polarization and yeast chemotropism by inhibiting receptor phosphorylation. Sci Signal. 2016;9 (423):ra38. doi: 10.1126/scisignal.aad4376. PubMed PMID:27072657 PubMed Central PMC4908976.
  12. Ghugtyal, V, Garcia-Rodas, R, Seminara, A, Schaub, S, Bassilana, M, Arkowitz, RA et al.. Phosphatidylinositol-4-phosphate-dependent membrane traffic is critical for fungal filamentous growth. Proc. Natl. Acad. Sci. U.S.A. 2015;112 (28):8644-9. doi: 10.1073/pnas.1504259112. PubMed PMID:26124136 PubMed Central PMC4507248.
  13. Arkowitz, RA, Bassilana, M. Rho GTPase-phosphatidylinositol phosphate interplay in fungal cell polarity. Biochem. Soc. Trans. 2014;42 (1):206-11. doi: 10.1042/BST20130226. PubMed PMID:24450653 .
  14. Martin, SG, Arkowitz, RA. Cell polarization in budding and fission yeasts. FEMS Microbiol. Rev. 2014;38 (2):228-53. doi: 10.1111/1574-6976.12055. PubMed PMID:24354645 .
  15. Ramírez-Zavala, B, Weyler, M, Gildor, T, Schmauch, C, Kornitzer, D, Arkowitz, R et al.. Activation of the Cph1-dependent MAP kinase signaling pathway induces white-opaque switching in Candida albicans. PLoS Pathog. 2013;9 (10):e1003696. doi: 10.1371/journal.ppat.1003696. PubMed PMID:24130492 PubMed Central PMC3795047.
  16. Corvest, V, Bogliolo, S, Follette, P, Arkowitz, RA, Bassilana, M. Spatiotemporal regulation of Rho1 and Cdc42 activity during Candida albicans filamentous growth. Mol. Microbiol. 2013;89 (4):626-48. doi: 10.1111/mmi.12302. PubMed PMID:23796158 .
  17. Guillas, I, Vernay, A, Vitagliano, JJ, Arkowitz, RA. Phosphatidylinositol 4,5-bisphosphate is required for invasive growth in Saccharomyces cerevisiae. J. Cell. Sci. 2013;126 (Pt 16):3602-14. doi: 10.1242/jcs.122606. PubMed PMID:23781030 .
  18. Deflorio, R, Brett, ME, Waszczak, N, Apollinari, E, Metodiev, MV, Dubrovskyi, O et al.. Phosphorylation of Gβ is crucial for efficient chemotropism in yeast. J. Cell. Sci. 2013;126 (Pt 14):2997-3009. doi: 10.1242/jcs.112797. PubMed PMID:23613469 .
  19. Arkowitz, RA. Cell polarity: wanderful exploration in yeast sex. Curr. Biol. 2013;23 (1):R10-2. doi: 10.1016/j.cub.2012.11.037. PubMed PMID:23305660 .
  20. Vernay, A, Schaub, S, Guillas, I, Bassilana, M, Arkowitz, RA. A steep phosphoinositide bis-phosphate gradient forms during fungal filamentous growth. J. Cell Biol. 2012;198 (4):711-30. doi: 10.1083/jcb.201203099. PubMed PMID:22891265 PubMed Central PMC3514036.
Search PubMed

 Doctoral position at University Côte d’Azur: Fungal Cell Biology

Light-dependent regulation of cell polarity in a fungal pathogen

The fungus Candida albicans is normally a harmless commensal that is found on mucosal surfaces of the gastrointestinal and urogenital tract in most healthy individuals. This commensal organism can cause superficial as well as life-threatening systemic infections in response to alterations of its environment, and is particularly aggressive in immuno-compromised individuals. As an opportunistic pathogen it can colonize and infect different body sites and is responsible for one of the most predominant fungal nosocomial infections. The ability of this fungus to switch from an ovoid form to a filamentous form is critical for its pathogenicity, in particularly its ability to invade and penetrate into host tissues and evade and burst out of host immune cells.

The recent advent of light-dependent approaches to control protein subcellular localization has made possible the specific alteration of growth, circumventing classical genetic and chemical perturbations. We have optimized such a light-dependent protein targeting system for C. albicans, which gives us exquisite control of growth in this organism. In addition, new variants of these systems have been established which facilitate their use and response time. Furthermore, a number of new, spectrally distinct fluorescent proteins, which we have optimized for use in C. albicans, now make it possible to follow different cellular processes simultaneously during light-dependent perturbation of growth and cell polarity. The goal of this project is to use such a light-dependent protein targeting to probe filamentous growth as well as invasive filamentous growth in a human fungal pathogen. The project will use a combination of molecular biology, microbiology and live cell microscopy to probe filamentous growth and morphogenesis in this fungal human pathogen.

We are seeking highly motivated candidates with a background in Cell Biology and interest in live cell imaging. Experience in Microbiology would be a plus.

Interested candidates can contact R. Arkowitz (arkowitz@unice.fr) by June 1st

 

1) M Bassilana, C Puerner & RA Arkowitz. Curr. Opin. Cell Biol. 2020 62:150-158.
2) PM Silva, C Puerner, A Seminara, M Bassilana & RA Arkowitz. Cell Rep. 2019 28:2231–2245.
3) RA Arkowitz & M Bassilana. F1000 Res. 2019 8.
4) A Weiner, F Orange, S Lacas-Gervais, K Rechav, V Ghugtyal, M Bassilana & RA Arkowitz. Cell Microbiol. 2019 21: e12963
5) H Labbaoui, S Bogliolo, V Ghugtyal, NV Solis, SG Filler, RA Arkowitz & M Bassilana. Plos Pathog. 2017 13: e1006205

 

/ ARKOWITZ, Job Offers, Open

Doctoral position at University Côte d’Azur: Fungal Cell Biology

Organelle dynamics in a human fungal pathogen at high temporal and spatial resolution

Worldwide, fungal infections cause significant morbidity and mortality and Candida species are the major etiological agent of such life-threatening infections and represent an emerging global microbial threat. A range of advances in medical treatment have increased life expectancy yet also dramatically increased the population of elderly as well as severely ill patients, highly susceptible to nosocomial infections, in particular those caused by fungi such as Candida albicans. C. albicans is normally a harmless commensal, found on mucosal surfaces of the gastrointestinal and urogenital tract in most healthy individuals that causes superficial as well as life-threatening systemic infections in response to alterations of its host environment. It is particularly aggressive in immuno-compromised individuals. The ability of this organism to switch from an ovoid to a filamentous form, concomitant with changes in cell surface antigens and enzyme production, is critical for its pathogenicity, in particular to invade host tissues and evade host immune cells. Many fungi, including C. albicans form elongated hyphal filaments that are tube-like cells in which growth is restricted to the tip. This dramatic yeast to filament cell shape change is a distinct advantage for studying the regulation of cell polarity and membrane traffic, critical for such morphogenesis. However, the hyphal apical zone is densely packed, with multiple membrane compartments including secretory vesicles below the light resolution limit and somewhat larger Golgi cisternae in a small volume at the filament tip and these compartments are highly dynamic making live cell imaging extremely challenging, in particular with high temporal and spatial resolution.

To understand the exquisite regulation of tip growth, the aim of this project is to quantitate the movement of membrane compartments in 3D with high spatial and temporal resolution. Conventional methods including fluorescence microscopy and electron microscopy suffer from either limited spatial or temporal resolution, whereas of super-resolution microscopy approaches, has made imaging with a resolution higher than that imposed by the diffraction limit of light possible. This interdisciplinary project (carried out with Laure BLANC‐FERAUD, I3S Laboratory – UMR CNRS 7271) will take advantage of fluorescent molecule blinking and their fluctuations over time, to generate super-resolved images with high temporal resolution. The goal of this project is to develop, optimize and apply such methods, specifically adapted to a multimodal microscope established at the iBV, to the investigate the reorganization of the membrane compartments during C. albicans filamentous growth, with high temporal and spatial resolution. This project will involve extensive state-of-the-art microscopy as well as optimization of image reconstruction and analyses computational algorithms.

We are seeking highly motivated candidates with a background in Cell Biology and interest in live cell imaging. Experience in Microbiology would be a plus.

Interested candidates can contact R. Arkowitz (arkowitz@unice.fr) by June 1st

 

1) M Bassilana, C Puerner & RA Arkowitz. Curr. Opin. Cell Biol. 2020 62:150-158.
2) PM Silva, C Puerner, A Seminara, M Bassilana & RA Arkowitz. Cell Rep. 2019 28:2231–2245.
3) RA Arkowitz & M Bassilana. F1000 Res. 2019 8.
4) A Weiner, F Orange, S Lacas-Gervais, K Rechav, V Ghugtyal, M Bassilana & RA Arkowitz. Cell Microbiol. 2019 21: e12963
5) H Labbaoui, S Bogliolo, V Ghugtyal, NV Solis, SG Filler, RA Arkowitz & M Bassilana. Plos Pathog. 2017 13: e1006205

/ ARKOWITZ, Job Offers, Open

Post-doctoral position in Fungal Cell Biology

A funded postdoctoral position (2 years in the first instance) is available at the Institute of Biology Valrose of the University of Côte d’Azur, Nice France to investigate the dynamics of polarity establishment in the human fungal pathogen, Candida albicans. C. albicans is a harmless commensal that in response to alterations of its environment can cause superficial as well as life-threatening systemic infections (1). The ability of this organism to switch from an ovoid to a filamentous form is critical for its pathogenicity. This dramatic cell shape change is a distinct advantage for studying cell polarity (2-4). We have recently optimized and established an optogenetic approach in C. albicans filamentous cells that gives us exquisite control of cell polarity in this fungal pathogen (5). In this ANR funded project our goal is to elucidate the interaction between two potential growth sites within the cell, as well as how different membrane compartments contribute to the initiation and stabilization of a new growth. The project will take advantage of cutting-edge imaging approaches, optogenetics and molecular genetics to investigate temporal and spatial control of fungal cell polarity.

We are seeking highly motivated candidates with a background in Cell Biology and previous experience in live cell imaging. Previous experience in Microbiology would be a plus.

Interested candidates can apply at the following link : https://emploi.cnrs.fr/Offres/CDD/UMR7277-ROBARK-004/Default.aspx

1) RA Arkowitz & M Bassilana. F1000 Res. 2019 8.
2) M Bassilana, C Puerner & RA Arkowitz. Curr. Opin. Cell Biol. 2019 62:150-158.
3) A Weiner, F Orange, S Lacas-Gervais, K Rechav, V Ghugtyal, M Bassilana & RA Arkowitz. Cell Microbiol. 2019 21: e12963
4) H Labbaoui, S Bogliolo, V Ghugtyal, NV Solis, SG Filler, RA Arkowitz & M Bassilana. Plos Pathog. 2017 13: e1006205
5) PM Silva, C Puerner, A Seminara, M Bassilana & RA Arkowitz. Cell Rep. 2019 28:2231–2245.

/ ARKOWITZ, Job Offers, Open

Super-resolution Dynamic Imaging of Intracellular Compartments in a Human Fungal Pathogen

Super-Dynamic-I2Fun

Worldwide, fungal infections cause significant morbidity and mortality and Candida species are major etiological agents of such lifethreatening infections. Candida albicans, a normally harmless commensal, is found on mucosal surfaces in most healthy individuals, yet it can cause superficial as well as life-threatening systemic infections. Its ability to switch from an ovoid to a filamentous form, in response to environmental cues, is critical for its pathogenicity. The apical zone of the filament is densely packed with multiple highly dynamic membrane compartments, including a cluster of secretory vesicles and Golgi cisternae. To understand the exquisite regulation of apical polarized growth, it will be critical to follow the movement of these compartments in 3D, with high spatial and temporal resolution. This PhD project will develop, optimize and apply super-resolution imaging approaches, in particular those taking advantage of fluorescent molecule blinking and their independent fluctuations in time, to study membrane traffic reorganization during filamentous growth in this medically relevant human fungal pathogen.

Candidates should have either a strong math/computational (convex/nonconvex sparse optimization in image processing, time series deconvolution, super-resolution) or a strong biological/microbiological (microscopy, mycology) background and be motivated to work in an interdisciplinary environment, with the possibility of short stays in life science biotechnology companies.

The recruited PhD student will follow different fluorescent protein fusions expressed in C. albicans live cells in super-resolved images obtained by reconstruction from wide-field acquisition. The entire acquisition pipeline will be optimized, from the experimental conditions to the reconstruction algorithm, for quantitative analysis of C. albicans hyphal subcellular structure and dynamics.

The supervisors have extensive experience in image processing and reconstruction (L. Blanc-Féraud; https://www-sop.inria.fr/members/Laure.Blanc_Feraud/) and fungal cell biology (R. Arkowitz; http://ibv.unice.fr/research-team/arkowitz/) and S. Schaub has developed a super-resolution microscope taking advantage of multiple-angle total internal reflection fluorescence (http://ibv.unice.fr/news/multi-angle-tirf-amolecular-resolution-optical-microscope-developed-at-ibv/).
For program information see http://univ-cotedazur.fr/fr/recherche/boosturcareer

Interested and motivated students please contact:

Robert Arkowitz Robert.ARKOWITZ@univ-cotedazur.fr
Laure Blanc-Féraud Laure.Blancferaud@cnrs.fr

 

PRINT OFFER

/ ARKOWITZ, Job Offers, Open

2015 - Marie Curie Multi-ITN (H2020-MSCA-ITN-2015)

2013 - Marie Curie Multi-ITN (FP7-PEOPLE-2013-ITN)

2012 - France Berkeley Fund Award

2005 - Marie Curie Host Fellowships for Early Stage Researchers (EST). FP6-2002-Mobility 2

2002 - Equipe Labellisée - La Ligue Contre le Cancer

2001 - Young Investigator Programme - EMBO

2001 - France Berkeley Fund Award

2001 - FRM Fondation pour la Recherche Médicale – BNP Paribas Award

2000 - Installation Award - FRM

2000 - ATIP - CNRS

1998 - EU Eurofan II (European Network for the Functional Analysis of Yeast Genes) FP5

iBV - Institut de Biologie Valrose

"Centre de Biochimie"

Université Nice Sophia Antipolis
Faculté des Sciences
Parc Valrose
06108 Nice cedex 2