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Curr Biol. 2017 Oct 9;27(19):2999-3009.e9. doi: 10.1016/j.cub.2017.08.031. Epub 2017 Sep 28.

Nesprin-1α-Dependent Microtubule Nucleation from the Nuclear Envelope via Akap450 Is Necessary for Nuclear Positioning in Muscle Cells.

Author information

1
Sorbonne Universités UPMC Université Paris 06, INSERM U974, CNRS FRE3617, Center for Research in Myology, GH Pitié Salpêtrière, 47 Boulevard de l'Hôpital, 75013 Paris, France.
2
Institute of Medical Biology, Agency for Science, Technology and Research (A(∗)STAR), 8A Biomedical Grove, No. 06-06 Immunos, Singapore 138648, Singapore.
3
Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A(∗)STAR), 61 Biopolis Drive, No. 07-48A Proteos, Singapore 138673, Singapore.
4
Department of Molecular and Cell Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7RH, UK.
5
Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
6
Charité-Universitätsmedizin Berlin, Virchowweg 6, 10117 Berlin, Germany.
7
Sorbonne Universités UPMC Université Paris 06, INSERM U974, CNRS FRE3617, Center for Research in Myology, GH Pitié Salpêtrière, 47 Boulevard de l'Hôpital, 75013 Paris, France. Electronic address: cadotbruno@gmail.com.
8
Sorbonne Universités UPMC Université Paris 06, INSERM U974, CNRS FRE3617, Center for Research in Myology, GH Pitié Salpêtrière, 47 Boulevard de l'Hôpital, 75013 Paris, France; Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028 Lisbon, Portugal. Electronic address: edgargomes@medicina.ulisboa.pt.

Abstract

The nucleus is the main microtubule-organizing center (MTOC) in muscle cells due to the accumulation of centrosomal proteins and microtubule (MT) nucleation activity at the nuclear envelope (NE) [1-4]. The relocalization of centrosomal proteins, including Pericentrin, Pcm1, and γ-tubulin, depends on Nesprin-1, an outer nuclear membrane (ONM) protein that connects the nucleus to the cytoskeleton via its N-terminal region [5-7]. Nesprins are also involved in the recruitment of kinesin to the NE and play a role in nuclear positioning in skeletal muscle cells [8-12]. However, a function for MT nucleation from the NE in nuclear positioning has not been established. Using the proximity-dependent biotin identification (BioID) method [13, 14], we found several centrosomal proteins, including Akap450, Pcm1, and Pericentrin, whose association with Nesprin-1α is increased in differentiated myotubes. We show that Nesprin-1α recruits Akap450 to the NE independently of kinesin and that Akap450, but not other centrosomal proteins, is required for MT nucleation from the NE. Furthermore, we demonstrate that this mechanism is disrupted in congenital muscular dystrophy patient myotubes carrying a nonsense mutation within the SYNE1 gene (23560 G>T) encoding Nesprin-1 [15, 16]. Finally, using computer simulation and cell culture systems, we provide evidence for a role of MT nucleation from the NE on nuclear spreading in myotubes. Our data thus reveal a novel function for Nesprin-1α/Nesprin-1 in nuclear positioning through recruitment of Akap450-mediated MT nucleation activity to the NE.

KEYWORDS:

Akap450; Nesprin-1; Nesprin-1α; centrosome; cytosim computer simulation; microtubules; non-centrosomal MTOC; nuclear envelope; nuclear positioning; skeletal muscle

PMID:
28966089
PMCID:
PMC5640514
DOI:
10.1016/j.cub.2017.08.031
[Indexed for MEDLINE]
Free PMC Article

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