Optogenetic reconstitution reveals that Dynein-Dynactin-NuMA clusters generate cortical spindle-pulling forces as a multi-arm ensemble
Preprint posted on March 06, 2018 https://www.biorxiv.org/content/early/2018/03/06/277202
Article now published in eLife at http://dx.doi.org/10.7554/eLife.36559
Mitotic cortical force machinery assembles on the plasma membrane and provides pulling forces on astral microtubules (MTs) that are important for the correct positioning of the spindle. Correct spindle positioning is important for both symmetric and asymmetric divisions, determining both cell size and fate following segregation of genetic material. In human cells, this machinery consists of the cortically anchored complex of Nuclear Mitotic Apparatus protein (NuMA), LGN and G alpha i (NuMA-LGN-Gαi), with cytoplasmic dynein and dynactin. The complex generates pulling forces on astral MTs through dynein’s minus-end directed motility and/or the control of MT dynamics. The authors use a light-induced membrane tethering system (iLID) to assess the mechanism by which NuMA contributes to cortical force generation (Figure 1A).
Using the iLID system, the authors show that spindles displace towards light-activated regions of the cortex upon NuMA, Dynein Heavy Chain (DHC) and p150 recruitment, and are able to show that repositioning of the light-induced cortical NuMA allows rotational reorientation of spindles. Although dynein-dynactin is required for cortical pulling, it is not sufficient for spindle displacement in the absence of NuMA. It contains a 200nm long central coiled-coil domain that is necessary for spindle pulling, and two additional microtubule-binding domains in the C-terminus. Together with dynein-dynactin, these regions allow NuMA clusters to efficiently capture and maintain associations with the plus-tips of astral microtubules in order to generate cortical pulling forces that are required for spindle positioning.
Why we chose this preprint:
We were drawn to this preprint thanks to the authors’ elegant use of a light induced system to reconstitute spindle pulling forces at the cortex. This preprint further highlights the power of using optogenetic tools to investigate protein function with precise spatial and temporal control, with the potential for much wider applications within other areas of cell biology. Here, by targeting the dynein-dynactin-NuMA (DDN) complex to the cortex, they further elucidate the underlying mechanisms controlling spindle positioning which is a topic of great interest to our lab.
This paper makes a significant step in dissecting the mechanism of cortical pulling by highlighting the requirement for both active dynein and additional microtubule-binding domains in NuMA to generate cortical forces. The authors note that NuMA tends to form distinct punctae on the membrane and hypothesize that it may be forming a higher-order complex in order to generate force. What might this structure look like? Finally, the authors show that slow spindle displacement can even be seen when microtubules are taxol-stabilized, removing microtubule depolymerisation at the cortex. In this case, what role are microtubule dynamics and pushing on the cortex playing during the process of spindle centering?
Posted on: 10th May 2018Read preprint
Also in the cell biology category:
Nix induced mitochondrial fission, mitophagy, and myocyte insulin resistance are abrogated by PKA phosphorylation
|Selected by||Sandra Franco Iborra|
Apical Constriction Reversal upon Mitotic Entry Underlies Different Morphogenetic Outcomes of Cell Division
|Selected by||Grace Lim|
Architectural RNA is required for heterochromatin organization
|Selected by||Ramona Jühlen|
preListscell biology category:in the
ASCB EMBO Annual Meeting 2019
A collection of preprints presented at the 2019 ASCB EMBO Meeting in Washington, DC (December 7-11)
|List by||Madhuja Samaddar, Ramona Jühlen, Amanda Haage, Laura McCormick|
EMBL Seeing is Believing – Imaging the Molecular Processes of Life
Preprints discussed at the 2019 edition of Seeing is Believing, at EMBL Heidelberg from the 9th-12th October 2019
|List by||Gautam Dey|
Preprints on autophagy and lysosomal degradation and its role in neurodegeneration and disease. Includes molecular mechanisms, upstream signalling and regulation as well as studies on pharmaceutical interventions to upregulate the process.
|List by||Sandra Malmgren Hill|
Lung Disease and Regeneration
This preprint list compiles highlights from the field of lung biology.
|List by||Rob Hynds|
A curated list of preprints related to cellular metabolism at Biorxiv by Pablo Ranea Robles from the Prelights community. Special interest on lipid metabolism, peroxisomes and mitochondria.
|List by||Pablo Ranea Robles|
BSCB/BSDB Annual Meeting 2019
Preprints presented at the BSCB/BSDB Annual Meeting 2019
|List by||Gautam Dey|
This list of preprints is focused on work expanding our knowledge on mitochondria in any organism, tissue or cell type, from the normal biology to the pathology.
|List by||Sandra Franco Iborra|
Biophysical Society Annual Meeting 2019
Few of the preprints that were discussed in the recent BPS annual meeting at Baltimore, USA
|List by||Joseph Jose Thottacherry|
ASCB/EMBO Annual Meeting 2018
This list relates to preprints that were discussed at the recent ASCB conference.
|List by||Gautam Dey, Amanda Haage|