Langdon Erin M.

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Langdon
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Erin M.
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  • Preprint
    mRNA structure determines specificity of a polyQ-driven phase separation
    ( 2018-04) Langdon, Erin M. ; Qiu, Yupeng ; Ghanbari Niaki, Amirhossein ; McLaughlin, Grace A. ; Weidmann, Chase ; Gerbich, Therese M. ; Smith, Jean A. ; Crutchley, John M. ; Termini, Christina M. ; Weeks, Kevin M. ; Myong, Sua ; Gladfelter, Amy S.
    RNA promotes liquid-liquid phase separation (LLPS) to build membrane-less compartments in cells. How distinct molecular compositions are established and maintained in these liquid compartments is unknown. Here we report that secondary structure allows mRNAs to self-associate and determines if an mRNA is recruited to or excluded from liquid compartments. The polyQ-protein Whi3 induces conformational changes in RNA structure and generates distinct molecular fluctuations depending on the RNA sequence. These data support a model in which structure-based, RNA-RNA interactions promote assembly of distinct droplets and protein-driven, conformational dynamics of the RNA maintain this identity. Thus, the shape of RNA can promote the formation and coexistence of the diverse array of RNA-rich liquid compartments found in a single cell.
  • Article
    Spatial heterogeneity of the cytosol revealed by machine learning-based 3D particle tracking
    (American Society for Cell Biology, 2020-06-29) McLaughlin, Grace A. ; Langdon, Erin M. ; Crutchley, John M. ; Holt, Liam J. ; Forest, M. Gregory ; Newby, Jay M. ; Gladfelter, Amy S.
    The spatial structure and physical properties of the cytosol are not well understood. Measurements of the material state of the cytosol are challenging due to its spatial and temporal heterogeneity. Recent development of genetically encoded multimeric nanoparticles (GEMs) has opened up study of the cytosol at the length scales of multiprotein complexes (20-60 nm). We developed an image analysis pipeline for 3D imaging of GEMs in the context of large, multinucleate fungi where there is evidence of functional compartmentalization of the cytosol for both the nuclear division cycle and branching. We applied a neural network to track particles in 3D and then created quantitative visualizations of spatially varying diffusivity. Using this pipeline to analyze spatial diffusivity patterns, we found that there is substantial variability in the properties of the cytosol. We detected zones where GEMs display especially low diffusivity at hyphal tips and near some nuclei, showing that the physical state of the cytosol varies spatially within a single cell. Additionally, we observed significant cell-to-cell variability in the average diffusivity of GEMs. Thus, the physical properties of the cytosol vary substantially in time and space and can be a source of heterogeneity within individual cells and across populations.