CDC-42 and RAC-1 regulate opposite chemotropisms in Neurospora crassa

Alexander Lichius, Andrew B. Goryachev, Mark D. Fricker, Boguslaw Obara, Ernestina Castro-Longoria, Nick D. Read

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    Cell polarization and fusion are crucial developmental processes that occur in response to intracellular and extracellular signals. Asexual spores (conidia) of the mold Neurospora crassa differentiate two types of polarized cell protrusions, germ tubes and conidial anastomosis tubes (CATs), which exhibit negative and positive chemotropism, respectively. We provide the first evidence that shared and separate functions of the Rho-type GTPases CDC- 42 and RAC-1 regulate these opposite chemotropisms. We demonstrate that RAC-1 is essential for CAT formation and cell fusion, whereas CDC-42 is necessary and sufficient for normal germ tube development. Cdc42-Rac-interactive-binding (CRIB) reporters were constructed to exclusively label locally activated GTP-bound GTPases. Time course analyses showed that repositioning of these activated GTPase clusters within germ tube and CAT tip apices controls directional growth in the absence of a tip-localized vesicle supply center (Spitzenkö rper). We propose a model in which the local assembly of a plasma-membraneassociated GTPase-PAK-MAPK signaling platform regulates chemoattractant perception and secretion in order to synchronize oscillatory cell-cell communication and directional CAT tip growth. © 2014. Published by The Company of Biologists Ltd.
    Original languageEnglish
    Pages (from-to)1953-1965
    Number of pages12
    JournalJournal of Cell Science
    Issue number9
    Publication statusPublished - 2014


    • CDC-42
    • Cell fusion
    • Chemotropism
    • Conidial anastomosis tube
    • CRIB
    • Directional tip growth
    • Neurospora crassa
    • RAC-1


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