Bio

Honors & Awards


  • Stanford Graduate Fellowship in Science and Engineering, Stanford University (2009-2011)

Education & Certifications


  • Master of Science, National Centre for Biological Sciences (2009)
  • Bachelor of Science, University Of Delhi, Biochemistry (2006)

Research & Scholarship

Current Research and Scholarly Interests


Phylogenetic profiling
Signaling control of translation
Collective cell migration

Lab Affiliations


Publications

Journal Articles


  • Systematic Discovery of Human Gene Function and Principles of Modular Organization through Phylogenetic Profiling CELL REPORTS Dey, G., Jaimovich, A., Collins, S. R., Seki, A., Meyer, T. 2015; 10 (6): 993-1006
  • Exploiting Cell-To-Cell Variability To Detect Cellular Perturbations PLOS ONE Dey, G., Gupta, G. D., Ramalingam, B., Sathe, M., Mayor, S., Thattai, M. 2014; 9 (3)

    Abstract

    Any single-cell-resolved measurement generates a population distribution of phenotypes, characterized by a mean, a variance, and a shape. Here we show that changes in the shape of a phenotypic distribution can signal perturbations to cellular processes, providing a way to screen for underlying molecular machinery. We analyzed images of a Drosophila S2R+ cell line perturbed by RNA interference, and tracked 27 single-cell features which report on endocytic activity, and cell and nuclear morphology. In replicate measurements feature distributions had erratic means and variances, but reproducible shapes; RNAi down-regulation reliably induced shape deviations in at least one feature for 1072 out of 7131 genes surveyed, as revealed by a Kolmogorov-Smirnov-like statistic. We were able to use these shape deviations to identify a spectrum of genes that influenced cell morphology, nuclear morphology, and multiple pathways of endocytosis. By preserving single-cell data, our method was even able to detect effects invisible to a population-averaged analysis. These results demonstrate that cell-to-cell variability contains accessible and useful biological information, which can be exploited in existing cell-based assays.

    View details for DOI 10.1371/journal.pone.0090540

    View details for Web of Science ID 000332475500063

    View details for PubMedID 24594940

  • Population Distribution Analyses Reveal a Hierarchy of Molecular Players Underlying Parallel Endocytic Pathways. PloS one Gupta, G. D., Dey, G., Mg, S., Ramalingam, B., Shameer, K., Thottacherry, J. J., Kalappurakkal, J. M., Howes, M. T., Chandran, R., Das, A., Menon, S., Parton, R. G., Sowdhamini, R., Thattai, M., Mayor, S. 2014; 9 (6): e100554

    Abstract

    Single-cell-resolved measurements reveal heterogeneous distributions of clathrin-dependent (CD) and -independent (CLIC/GEEC: CG) endocytic activity in Drosophila cell populations. dsRNA-mediated knockdown of core versus peripheral endocytic machinery induces strong changes in the mean, or subtle changes in the shapes of these distributions, respectively. By quantifying these subtle shape changes for 27 single-cell features which report on endocytic activity and cell morphology, we organize 1072 Drosophila genes into a tree-like hierarchy. We find that tree nodes contain gene sets enriched in functional classes and protein complexes, providing a portrait of core and peripheral control of CD and CG endocytosis. For 470 genes we obtain additional features from separate assays and classify them into early- or late-acting genes of the endocytic pathways. Detailed analyses of specific genes at intermediate levels of the tree suggest that Vacuolar ATPase and lysosomal genes involved in vacuolar biogenesis play an evolutionarily conserved role in CG endocytosis.

    View details for DOI 10.1371/journal.pone.0100554

    View details for PubMedID 24971745

  • Parallel measurement of dynamic changes in translation rates in single cells NATURE METHODS Han, K., Jaimovich, A., Dey, G., Ruggero, D., Meyuhas, O., Sonenberg, N., Meyer, T. 2014; 11 (1): 86-?

    Abstract

    Protein concentrations are often regulated by dynamic changes in translation rates. Nevertheless, it has been challenging to directly monitor changes in translation in living cells. We have developed a reporter system to measure real-time changes of translation rates in human or mouse individual cells by conjugating translation regulatory motifs to sequences encoding a nuclear targeted fluorescent protein and a controllable destabilization domain. Application of the method showed that individual cells undergo marked fluctuations in the translation rate of mRNAs whose 5' terminal oligopyrimidine (5' TOP) motif regulates the synthesis of ribosomal proteins. Furthermore, we show that small reductions in amino acid levels signal through different mTOR-dependent pathways to control TOP mRNA translation, whereas larger reductions in amino acid levels control translation through eIF2A. Our study demonstrates that dynamic measurements of single-cell activities of translation regulatory motifs can be used to identify and investigate fundamental principles of translation.

    View details for DOI 10.1038/NMETH.2729

    View details for Web of Science ID 000329178200032

    View details for PubMedID 24213167

  • Survival strategies of a sterol auxotroph DEVELOPMENT Carvalho, M., Schwudke, D., Sampaio, J. L., Palm, W., Riezman, I., Dey, G., Gupta, G. D., Mayor, S., Riezman, H., Shevchenko, A., Kurzchalia, T. V., Eaton, S. 2010; 137 (21): 3675-3685

    Abstract

    The high sterol concentration in eukaryotic cell membranes is thought to influence membrane properties such as permeability, fluidity and microdomain formation. Drosophila cannot synthesize sterols, but do require them for development. Does this simply reflect a requirement for sterols in steroid hormone biosynthesis, or is bulk membrane sterol also essential in Drosophila? If the latter is true, how do they survive fluctuations in sterol availability and maintain membrane homeostasis? Here, we show that Drosophila require both bulk membrane sterol and steroid hormones in order to complete adult development. When sterol availability is restricted, Drosophila larvae modulate their growth to maintain membrane sterol levels within tight limits. When dietary sterol drops below a minimal threshold, larvae arrest growth and development in a reversible manner. Strikingly, membrane sterol levels in arrested larvae are dramatically reduced (dropping sixfold on average) in most tissues except the nervous system. Thus, sterols are dispensable for maintaining the basic membrane biophysical properties required for cell viability; these functions can be performed by non-sterol lipids when sterols are unavailable. However, bulk membrane sterol is likely to have essential functions in specific tissues during development. In tissues in which sterol levels drop, the overall level of sphingolipids increases and the proportion of different sphingolipid variants is altered. These changes allow survival, but not growth, when membrane sterol levels are low. This relationship between sterols and sphingolipids could be an ancient and conserved principle of membrane homeostasis.

    View details for DOI 10.1242/dev.044560

    View details for Web of Science ID 000283669300015

    View details for PubMedID 20940226

  • Analysis of Endocytic Pathways in Drosophila Cells Reveals a Conserved Role for GBF1 in Internalization via GEECs PLOS ONE Gupta, G. D., Swetha, M. G., Kumari, S., Lakshminarayan, R., Dey, G., Mayor, S. 2009; 4 (8)

    Abstract

    In mammalian cells, endocytosis of the fluid phase and glycosylphosphatidylinositol-anchored proteins (GPI-APs) forms GEECs (GPI-AP enriched early endosomal compartments) via an Arf1- and Cdc42-mediated, dynamin independent mechanism. Here we use four different fluorescently labeled probes and several markers in combination with quantitative kinetic assays, RNA interference and high resolution imaging to delineate major endocytic routes in Drosophila cultured cells. We find that the hallmarks of the pinocytic GEEC pathway are conserved in Drosophila and identify garz, the fly ortholog of the GTP exchange factor GBF1, as a novel component of this pathway. Live confocal and TIRF imaging reveals that a fraction of GBF1 GFP dynamically associates with ABD RFP (a sensor for activated Arf1 present on nascent pinosomes). Correspondingly, a GTP exchange mutant of GBF1 has altered ABD RFP localization in the evanescent field and is impaired in fluid phase uptake. Furthermore, GBF1 activation is required for the GEEC pathway even in the presence of Brefeldin A, implying that, like Arf1, it has a role in endocytosis that is separable from its role in secretion.

    View details for DOI 10.1371/journal.pone.0006768

    View details for Web of Science ID 000269335000014

    View details for PubMedID 19707569

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