Biology subjects

Driscoll, T.

Publications and source records attributed to Driscoll, T..

3 recordsLinked to original sources

bioRxiv2018

The Drosophila Cortactin Binding Protein 2 homolog, Nausicaa, regulates lamellipodial actin dynamics in a Cortactin-dependent manner.

Drosophila CG10915 is an uncharacterized protein coding gene with sequence similarity to human Cortactin Binding Protein 2 (CTTNBP2) and Cortactin Binding Protein 2 N-terminal like (CTTNBP2NL). We have named this gene Nausicaa (naus) and characterize it through a combination of quantitative live-cell total internal reflection fluorescence (TIRF) microscopy, electron microscopy, RNAi depletion, and genetics. We found that Naus co-localizes with F-actin and Cortactin in the lamellipodia of Drosophila S2R+ and D25c2 cells and this localization is lost following Cortactin or Arp2/3 depletion or by mutations that disrupt a conserved proline patch found in its mammalian homologs. Using Permeabilization Activated Reduction in Fluorescence (PARF) and Fluorescence Recovery after Photo-bleaching (FRAP), we find that depletion of Cortactin alters Naus dynamics leading to a decrease in its half-life. Furthermore, we discovered that Naus depletion in S2R+ cells led to a decrease in actin retrograde flow and a lamellipodia characterized by long, unbranched filaments. We demonstrate that these alterations to the dynamics and underlying actin architecture also affect D25c2 cell migration and decrease arborization in Drosophila neurons. We present the novel hypothesis that Naus functions to slow Cortactins disassociation from Arp2/3 nucleated branch junctions, thereby increasing both branch nucleation and junction stability.

cell biology↗

bioRxiv2018

microRNA-dependent regulation of biomechanical genes establishes tissue stiffness homeostasis

The mechanical properties of tissues, which are determined primarily by their extracellular matrix (ECM), are largely stable over time despite continual turnover of ECM constituents 1,2. These observations imply active homeostasis, where cells sense and adjust rates of matrix synthesis, assembly and degradation to keep matrix and tissue properties within the optimal range. However, the regulatory pathways that mediate this process are essentially unknown3. Genome-wide analyses of endothelial cells revealed abundant microRNA-mediated regulation of cytoskeletal, adhesive and extracellular matrix (CAM) mRNAs. High-throughput assays showed co-transcriptional regulation of microRNA and CAM genes on stiff substrates, which buffers CAM expression. Disruption of global or individual microRNA-dependent suppression of CAM genes induced hyper-adhesive, hyper-contractile phenotypes in multiple systems in vitro, and increased tissue stiffness in the zebrafish fin-fold during homeostasis and regeneration in vivo. Thus, a network of microRNAs and CAM mRNAs mediate tissue mechanical homeostasis.

cell biology↗

bioRxiv2017

New Insights into the Conformational Activation of Full-Length Integrin

Integrin binding to extracellular matrix proteins is regulated by conformational transitions from closed, low affinity states to open, high affinity states. However, the pathways of integrin conformational activation remain incompletely understood. Here, by combining all-atom molecular dynamics simulation, coarse-graining, heterogeneous elastic network modeling, and experimental ligand binding measurements, we test the effect of integrin {beta} mutations that destabilize the closed conformation. Our results support a \"deadbolt\" model of integrin activation, where extension of the headpiece is not coupled to leg separation, consistent with recent cryo-EM reconstructions of integrin intermediates. Moreover, our results are inconsistent with a \"switchblade-like\" mechanism. The data show that locally correlated atomistic motions are likely responsible for extension of integrin headpiece before separation of transmembrane legs, without persistence of these correlations across the entire protein. By combining modeling and simulation with experiment, this study provides new insight into the structural basis of full-length integrin activation.

biophysics↗