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Nat Commun. 2018 Jul 9;9(1):2659. doi: 10.1038/s41467-018-04991-2.

Microtubule minus-end aster organization is driven by processive HSET-tubulin clusters.

Author information

1
Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, 37232, USA.
2
Division of Hematology/Oncology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
3
Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, 48109-2216, USA.
4
The Life Sciences Institute, University of Michigan Medical School, Ann Arbor, MI, 48109-2216, USA.
5
Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, 37232, USA. marija.zanic@vanderbilt.edu.
6
Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, 37232, USA. marija.zanic@vanderbilt.edu.
7
Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, 37232, USA. oryoma@umich.edu.
8
Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, 48109-2216, USA. oryoma@umich.edu.
9
The Life Sciences Institute, University of Michigan Medical School, Ann Arbor, MI, 48109-2216, USA. oryoma@umich.edu.

Abstract

Higher-order structures of the microtubule (MT) cytoskeleton are comprised of two architectures: bundles and asters. Although both architectures are critical for cellular function, the molecular pathways that drive aster formation are poorly understood. Here, we study aster formation by human minus-end-directed kinesin-14 (HSET/KIFC1). We show that HSET is incapable of forming asters from preformed, nongrowing MTs, but rapidly forms MT asters in the presence of soluble (non-MT) tubulin. HSET binds soluble (non-MT) tubulin via its N-terminal tail domain to form heterogeneous HSET-tubulin clusters containing multiple motors. Cluster formation induces motor processivity and rescues the formation of asters from nongrowing MTs. We then show that excess soluble (non-MT) tubulin stimulates aster formation in HeLa cells overexpressing HSET during mitosis. We propose a model where HSET can toggle between MT bundle and aster formation in a manner governed by the availability of soluble (non-MT) tubulin.

PMID:
29985404
PMCID:
PMC6037785
DOI:
10.1038/s41467-018-04991-2
[Indexed for MEDLINE]
Free PMC Article

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