Spatiotemporally controlled Myosin relocalization and internal pressure cause biased cortical extension to generate sibling cell size asymmetry

Tri Thanh Pham, Arnaud Monnard, Jonne Helenius, Erik Lund, Nicole Lee, Daniel Mueller, Clemens Cabernard

Preprint posted on May 01, 2018

The right cell at the right size: how myosin-dependent tension and hydrostatic pressure coordinate to achieve physical asymmetry.

Selected by Giuliana Clemente

Categories: cell biology

Context and Background:

Cells of a developing organism can undergo either symmetric or asymmetric cell division. Upon symmetric cell division, the dividing cell generates two daughters of identical fate and size. Asymmetric cell division is a peculiar trait of stem cells and it serves both, self-renewal as well as lineage commitment and differentiation. In the context of cell division, asymmetry is generally meant as asymmetric inheritance of cell fate determinants or as a difference in the type and strength of signal(s) received from the niche. Furthermore, this form of division is often accompanied by asymmetry in cell size.

Drosophila Neuroblasts (NBs) represent a well-established system to study asymmetric stem cell division. These are large cells that repetitively divide to generate another self-renewing neuroblast and a smaller progenitor known as Ganglion Mother Cell (GMC). Neuroblasts generate cell-fate asymmetry by the establishment of a robust polarity axis. The generation of the polarity cues allows the cells to segregate fate determinants to the basal side, ensuring their subsequent inheritance by the future GMC. How cell size asymmetry is generated in the system is still somewhat elusive. Some evidence suggests that an apical-to-basal flow of Myosin-II provides a mean to generate unequally sized daughter cells (Cabernard et al, 2010; Connel et al. 2011; Ou et al. 2010). However it is still unclear by which mechanism Myosin-II promotes physical asymmetry and whether other forces acting on the system contribute to the outcome.

Key findings:

Pham et al. combine atomic force microscopy with the amenability and genetic power of Drosophila and suggest a multi-step model in which coordinated and dynamic changes in cortical tension and hydrostatic pressure direct apical membrane expansion and basal constriction, resulting in sibling size asymmetry (Figure 1). Specifically, they propose that an increase in internal pressure accompanied by a reduction in apical cortical tension drives apical expansion. At the onset of anaphase, once the internal pressure levels drastically reduce to basal level, a contractile ring forms shifted toward the basal side. This basal constriction starts basal membrane expansion and supports apical expansion as well.


Figure1: Proposed working model adopted from Figure 4 of the preprint.


Why I chose this paper:

Are cells smart entities able to receive, interpret and integrate multiple signals and tune their response accordingly? The question of cell intelligence is the big mystery that has been fascinating scientists for decades. How do cells know their relationship with the external environment? How are they able to travel long distances and get to the right place at the right time? Similarly, how do cells know what their right size should be in relation with the outer space and how do they tune their size during growth and division?

I chose the work from Pham and colleagues as they aim to address this latter question by trying to set a molecular base to the establishment of sibling cell asymmetry. This is physiologically relevant especially in the stem cell field, where keeping the right size ratio between the two daughter cells is crucial for cell specification and determination (Ou et al., 2010).

Questions for the Authors:

As the authors mention in the discussion, there is still space for a better characterisation of the process. The model indeed does not explain how internal pressure increases and whether this is under cell-cycle control. Another question would be: what is the membrane reservoir? Is new membrane delivered asymmetrically or asymmetric lipid distribution is achieved lately through the activity of the acto-myosin ring?

This area of research is undoubtedly expanding. In fact, on a smaller scale, one could ask how do cells know the size of their organelles? And by what molecular mechanisms do they control it? In this regard a good example has been recently offered by the Raff lab that published about regulation of centriole size and identified in Plk-4 the “homeostatic clock” which sets the time and rate of centriole growth (Aydogan M. G. et al., 2018).


1. Cabernard, C., Prehoda, K.E., Doe, C.Q., 2010. A spindle-independent cleavage furrow positioning

pathway. Nature 467, 91–94. doi:10.1038/nature09334

2. Connell, M., Cabernard, C., Ricketson, D., Doe, C.Q., Prehoda, K.E., 2011. Asymmetric cortical

extension shifts cleavage furrow position in Drosophila neuroblasts. Mol. Biol. Cell 22, 4220–4226


3. Ou, G., Stuurman, N., D’Ambrosio, M., Vale, R.D., 2010. Polarized myosin produces unequal-size

daughters during asymmetric cell division. Science 330, 677–680. doi:10.1126/science.1196112

4. Mustafa G. Aydogan, ProAlan WainmanSaroj Saurya, Thomas L. Steinacker, Anna Caballe, Zsofia A. Novak, Janina Baumbach, Nadine Muschalik, Jordan W. Raff. A homeostatic clock sets daughter centriole size in flies. Journal of Cell Biology 217 (4), 1233-1248. doi: 10.1083/jcb.201801014




Posted on: 24th June 2018 , updated on: 25th June 2018

Read preprint (No Ratings Yet)

Have your say

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sign up to customise the site to your preferences and to receive alerts

Register here

preLists in the cell biology category:

FENS 2020

A collection of preprints presented during the virtual meeting of the Federation of European Neuroscience Societies (FENS) in 2020


List by Ana Dorrego-Rivas

Planar Cell Polarity – PCP

This preList contains preprints about the latest findings on Planar Cell Polarity (PCP) in various model organisms at the molecular, cellular and tissue levels.


List by Ana Dorrego-Rivas

BioMalPar XVI: Biology and Pathology of the Malaria Parasite

[under construction] Preprints presented at the (fully virtual) EMBL BioMalPar XVI, 17-18 May 2020 #emblmalaria


List by Dey Lab, Samantha Seah


Cell Polarity

Recent research from the field of cell polarity is summarized in this list of preprints. It comprises of studies focusing on various forms of cell polarity ranging from epithelial polarity, planar cell polarity to front-to-rear polarity.


List by Yamini Ravichandran

TAGC 2020

Preprints recently presented at the virtual Allied Genetics Conference, April 22-26, 2020. #TAGC20


List by Maiko Kitaoka, Madhuja Samaddar, Miguel V. Almeida, Sejal Davla, Jennifer Ann Black, Dey Lab

3D Gastruloids

A curated list of preprints related to Gastruloids (in vitro models of early development obtained by 3D aggregation of embryonic cells). Preprint missing? Don't hesitate to let us know.


List by Paul Gerald L. Sanchez and Stefano Vianello

ECFG15 – Fungal biology

Preprints presented at 15th European Conference on Fungal Genetics 17-20 February 2020 Rome


List by Hiral Shah

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, Maiko Kitaoka

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 Dey Lab


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

Cellular metabolism

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 Dey Lab


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 Dey Lab, Amanda Haage