Maitreyi Das
University of Miami
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Maitreyi Das.
Science | 2012
Maitreyi Das; Tyler Drake; David J. Wiley; Peter Buchwald; Dimitrios Vavylonis; Fulvia Verde
Pole to Pole How do fission yeast cells decide when to grow at a single end (or pole) of the cell or whether to grow in a multipolar manner? Das et al. (p. 239, published online 17 May) found that accumulation of the active form of the small guanine nucleotide–binding protein Cdc42 at the growing tip of the cell oscillated with a period of a few minutes. In cells growing at one pole, the oscillations were primarily present at that pole and during bipolar growth symmetrical anticorrelated oscillations were observed. Dynamic competition for Cdc42 between multiple growth zones could represent a flexible mechanism to modulate cell growth asymmetry. The regulation of a yeast cell-growth enzyme is dynamic rather than on-off. Cells promote polarized growth by activation of Rho-family protein Cdc42 at the cell membrane. We combined experiments and modeling to study bipolar growth initiation in fission yeast. Concentrations of a fluorescent marker for active Cdc42, Cdc42 protein, Cdc42-activator Scd1, and scaffold protein Scd2 exhibited anticorrelated fluctuations and oscillations with a 5-minute average period at polarized cell tips. These dynamics indicate competition for active Cdc42 or its regulators and the presence of positive and delayed negative feedbacks. Cdc42 oscillations and spatial distribution were sensitive to the amounts of Cdc42-activator Gef1 and to the activity of Cdc42-dependent kinase Pak1, a negative regulator. Feedbacks regulating Cdc42 oscillations and spatial self-organization appear to provide a flexible mechanism for fission yeast cells to explore polarization states and to control their morphology.
Current Biology | 2009
Maitreyi Das; David J. Wiley; Xi Chen; Kavita Shah; Fulvia Verde
The conserved NDR kinase regulates cell morphogenesis and polarized cell growth in different eukaryotic cells ranging from yeast to neurons. Although studies have unraveled the mechanism of regulation of NDR kinase activity, the mechanism of morphology control by NDR and the effectors that mediate NDR function are unknown. Via a chemical genetic approach, we show that the fission yeast NDR homolog, Orb6 kinase, maintains polarized cell growth at the cell tips by spatially regulating the localization of Cdc42 GTPase, a key morphology regulator. Loss of Orb6 kinase activity leads to the recruitment of Cdc42 GTPase and the Cdc42-dependent formin For3, normally found only at the cell tips, to the cell sides. Furthermore, we show that loss of Orb6 kinase activity leads to ectopic lateral localization of the Cdc42 guanine nucleotide exchange factor (GEF) Gef1, but not of the other Cdc42 GEF, Scd1. Consistent with these observations, gef1 deletion suppresses the increased cell diameter phenotype of orb6 mutants. In contrast, the microtubule cytoskeleton and the localization of the microtubule-dependent polarity markers Tea1 and Tea4 are not altered by loss of Orb6 kinase activity. Our findings indicate that the conserved NDR kinase Orb6 regulates cell polarity by spatially restricting the localization and activity of Cdc42 GTPase.
Molecular Biology of the Cell | 2015
Maitreyi Das; Illyce Nuñez; Marbelys Rodriguez; David J. Wiley; Juan Carlos de Vicente Rodríguez; Ali Sarkeshik; John R. Yates; Peter Buchwald; Fulvia Verde
The 14-3-3 protein Rad24 modulates the availability of Cdc42 GEF Gef1, spatially regulating Cdc42 activity during cell morphogenesis. Gef1 is sequestered in the cytoplasm upon 14-3-3 interaction, mediated by Orb6 kinase. The resulting competition for Gef1 promotes anticorrelated Cdc42 oscillations at cell tips.
Current Genetics | 2008
Revathi S. Iyer; Maitreyi Das; Paike Jayadeva Bhat
In response to carbon and/or nitrogen limitation, diploid cells of Saccharomyces cerevisiae either sporulate or develop pseudohyphae. Although the signal transduction pathways leading to these developmental changes have been extensively studied, how nutritional signals are integrated is not clearly understood. Results of this study indicate that reducing glucose concentration from 2% (SLAD) to 0.05% (SLALD) causes an increase in the magnitude of filamentation as well as a discernible reduction in the time required for pseudohyphal development. Further, the pseudohyphal defect of gpa2, gpr1and gpa2gpr1 but not the mep2 mutant strain is overcome on SLALD. Low glucose also induced pseudohyphae in mep2gpr1 but not mep2gpa2 strain suggesting that GPR1 inhibits pseudohyphae by inhibiting GPA2 function. Accordingly, deleting GPA2 in mep2gpr1 mutant abrogated pseudohyphae formation in SLALD. Further, replenishment of glucose suppressed pseudohyphal differentiation in wild-type cells grown in SLAD medium. However, in SLALD, glucose replenishment suppressed the filamentation response of gpa2 mutants but not that of strains carrying the wild-type GPA2. Increased trehalose levels correlated with decreased pseudohyphae formation. Results of this study demonstrate that filamentation in response to nitrogen limitation occurs as glucose becomes limiting.
Molecular Biology of the Cell | 2016
Bin Wei; Brian S. Hercyk; Nicholas Mattson; Ahmad Mohammadi; Julie Rich; Erica DeBruyne; Mikayla M. Clark; Maitreyi Das
Cdc42 is activated in a unique spatiotemporal manner during cytokinesis due to the localization of its GEFs, Gef1 and Scd1. The fission yeast Gef1 localizes to the actomyosin ring and promotes timely onset of ring constriction. Scd1 localizes to the ingressing membrane to promote septum formation.
Biochemical Society Transactions | 2013
Maitreyi Das; Fulvia Verde
Cell polarization is fundamental to many cellular processes, including cell differentiation, cell motility and cell fate determination. A key regulatory enzyme in the control of cell morphogenesis is the conserved Rho GTPase Cdc42, which breaks symmetry via self-amplifying positive-feedback mechanisms. Additional mechanisms of control, including competition between different sites of polarized cell growth and time-delayed negative feedback, define a cellular-level system that promotes Cdc42 oscillatory dynamics and modulates activated Cdc42 intracellular distribution.
eLife | 2016
Illyce Nuñez; Marbelys Rodriguez Pino; David J. Wiley; Maitreyi Das; Chuan Chen; Tetsuya Goshima; Kazunori Kume; Dai Hirata; Takashi Toda; Fulvia Verde
RNA-binding proteins contribute to the formation of ribonucleoprotein (RNP) granules by phase transition, but regulatory mechanisms are not fully understood. Conserved fission yeast NDR (Nuclear Dbf2-Related) kinase Orb6 governs cell morphogenesis in part by spatially controlling Cdc42 GTPase. Here we describe a novel, independent function for Orb6 kinase in negatively regulating the recruitment of RNA-binding protein Sts5 into RNPs to promote polarized cell growth. We find that Orb6 kinase inhibits Sts5 recruitment into granules, its association with processing (P) bodies, and degradation of Sts5-bound mRNAs by promoting Sts5 interaction with 14-3-3 protein Rad24. Many Sts5-bound mRNAs encode essential factors for polarized cell growth, and Orb6 kinase spatially and temporally controls the extent of Sts5 granule formation. Disruption of this control system affects cell morphology and alters the pattern of polarized cell growth, revealing a role for Orb6 kinase in the spatial control of translational repression that enables normal cell morphogenesis. DOI: http://dx.doi.org/10.7554/eLife.14216.001
bioRxiv | 2018
Brian S. Hercyk; Julie Rich; Maitreyi Das
The small GTPase Cdc42, a conserved regulator of cell polarity in eukaryotes, is activated by two GEFs, Gef1 and Scd1, in fission yeast. Gef1 and Scd1 localize sequentially to the division site to activate Cdc42 for efficient cytokinesis. The significance of multiple Cdc42 GEFS is not well understood. Here we report a novel interplay between Gef1 and Scd1 that fine-tunes Cdc42 activation during two cellular programs: cytokinesis and polarized growth. We find that Gef1 promotes Scd1 localization to the division site during cytokinesis. During polarized growth, Gef1 is required for bipolar Scd1 localization. Gef1 recruits Scd1 through the recruitment of the scaffold Scd2; we propose this facilitates polarized cell growth at a second site. In turn, Scd1 restricts Gef1 localization to the division site and to the cell cortex, thus maintaining polarity. Our results suggest that crosstalk between GEFs is a conserved mechanism that orchestrates Cdc42 activation during complex processes.
bioRxiv | 2018
Udodirim Onwubiko; Paul J. Mlynarczyk; Bin Wei; Julius Habiyaremye; Amanda Clack; Steven M. Abel; Maitreyi Das
During cytokinesis, fission yeast coordinates actomyosin ring constriction with septum ingression, resulting in concentric furrow formation. Mechanisms coordinating septum ingression with the actomyosin ring remain unclear. We report that cells lacking the Cdc42 activator Gef1, combined with an activated allele of the formin, Cdc12, display non-concentric furrowing. Although cells that furrow non-concentrically display normal actomyosin rings, the scaffold Cdc15 is unevenly distributed along the ring. This suggests that after ring assembly, uniform Cdc15 distribution along the ring drives proper furrow formation. We find that Cdc15 levels at the ring are reduced in the activated cdc12 mutant, or upon disruption of Arp2/3 complex-dependent endocytic patches. Furthermore, Cdc15 levels in endocytic patches increase in gef1 mutants. We hypothesize that assembled rings recruit Cdc15 from endocytic patches. Patches with higher Cdc15 levels and slower ring-association rate lead to uneven Cdc15 distribution. Based on this hypothesis we developed a mathematical model that captures experimentally observed Cdc15 distributions along the ring. We propose that, at the ring, Gef1 and endocytic events promote uniform Cdc15 distribution to enable proper septum ingression and concentric furrow formation. Summary Statement Gef1 and endocytic events at the assembled actomyosin ring facilitate uniform Cdc15 distribution along the ring thus enabling concentric furrow formation.
Molecular Biology of the Cell | 2007
Maitreyi Das; David J. Wiley; Saskia Medina; Helen A. Vincent; Michelle D. Larrea; Andrea S. Oriolo; Fulvia Verde