Publications by authors named "Brigette Y Monroy"

3 Publications

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A Combinatorial MAP Code Dictates Polarized Microtubule Transport.

Dev Cell 2020 04 27;53(1):60-72.e4. Epub 2020 Feb 27.

Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA. Electronic address:

Many eukaryotic cells distribute their intracellular components asymmetrically through regulated active transport driven by molecular motors along microtubule tracks. While intrinsic and extrinsic regulation of motor activity exists, what governs the overall distribution of activated motor-cargo complexes within cells remains unclear. Here, we utilize in vitro reconstitution of purified motor proteins and non-enzymatic microtubule-associated proteins (MAPs) to demonstrate that MAPs exhibit distinct influences on the motility of the three main classes of transport motors: kinesin-1, kinesin-3, and cytoplasmic dynein. Further, we dissect how combinations of MAPs affect motors and unveil MAP9 as a positive modulator of kinesin-3 motility. From these data, we propose a general "MAP code" that has the capacity to strongly bias directed movement along microtubules and helps elucidate the intricate intracellular sorting observed in highly polarized cells such as neurons.
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http://dx.doi.org/10.1016/j.devcel.2020.01.029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7181406PMC
April 2020

Dual control of Kinesin-1 recruitment to microtubules by Ensconsin in neuroblasts and oocytes.

Development 2019 04 17;146(8). Epub 2019 Apr 17.

Univ. Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, F-35000 Rennes, France

Ensconsin (also known as MAP7) controls spindle length, centrosome separation in brain neuroblasts (NBs) and asymmetric transport in oocytes. The control of spindle length by Ensconsin is Kinesin-1 independent but centrosome separation and oocyte transport require targeting of Kinesin-1 to microtubules by Ensconsin. However, the molecular mechanism used for this targeting remains unclear. Ensconsin contains a microtubule (MT)-binding domain (MBD) and a Kinesin-binding domain (KBD). Rescue experiments show that only full-length Ensconsin restores the spindle length phenotype. KBD expression rescues centrosome separation defects in NBs, but not the fast oocyte streaming and the localization of Staufen and Gurken. Interestingly, the KBD can stimulate Kinesin-1 targeting to MTs and We propose that a KBD and Kinesin-1 complex is a minimal activation module that increases Kinesin-1 affinity for MTs. Addition of the MBD present in full-length Ensconsin allows this process to occur directly on the MT and triggers higher Kinesin-1 targeting. This dual regulation by Ensconsin is essential for optimal Kinesin-1 targeting to MTs in oocytes, but not in NBs, illustrating the importance of adapting Kinesin-1 recruitment to different biological contexts.
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http://dx.doi.org/10.1242/dev.171579DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6503980PMC
April 2019

Competition between microtubule-associated proteins directs motor transport.

Nat Commun 2018 04 16;9(1):1487. Epub 2018 Apr 16.

Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, 95616, USA.

Within cells, motor and non-motor microtubule-associated proteins (MAPs) simultaneously converge on the microtubule. How the binding activities of non-motor MAPs are coordinated and how they contribute to the balance and distribution of motor transport is unknown. Here, we examine the relationship between MAP7 and tau owing to their antagonistic roles in vivo. We find that MAP7 and tau compete for binding to microtubules, and determine a mechanism by which MAP7 displaces tau from the lattice. MAP7 promotes kinesin-based transport in vivo and strongly recruits kinesin-1 to the microtubule in vitro, providing evidence for direct enhancement of motor motility by a MAP. Both MAP7 and tau strongly inhibit kinesin-3 and have no effect on cytoplasmic dynein, demonstrating that MAPs differentially control distinct classes of motors. Overall, these results reveal a general principle for how MAP competition dictates access to the microtubule to determine the correct distribution and balance of motor activity.
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http://dx.doi.org/10.1038/s41467-018-03909-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5902456PMC
April 2018