Download How do cells position their division plane?

How do cells position their division plane?
Nicolas Minc
Group Leader
Institut Jacques Monod
Contact: [email protected]
Cells divide at specific location
C. Elegans zygote
Sea urchin Embryos
10 mic
Fission yeast cells
Division plane positioning
Xenopus cells
Zebrafish embryo
Drosophila epithelium
C. Elegans embryo
Sea cucumber embryo
(Synapta maculata)
How do cells position their division plane?
?
?
?
Outline
1- A historical view on the question
2- The steps of cell divison
3- Microtubule forces
4- Some classical case studies
5- Predicting division position and orientation
Outline
1- A historical view on the question
2- The steps of cell divison
3- Microtubule forces
4- Some classical case studies
5- Predicting division position and orientation
Old rules for division positioning
Sachs’ rules for plant cells:
Daughter cells of same size and division plane perpendicular to existing wall
Sachs, 1878; Besson and Dumais, PNAS 2011
Old rules for division positioning
Sea cucumber Synapata
Oscar Hertwig’s constrained frog egg
Hertwig’s rules for animal cells
Division at cell center of mass and perpendicular to longest axis
Hertwig, 1884; Minc and Piel , Trends Cell Biol, 2012
Old rules for division positioning
Sea cucumber Synapata
Oscar Hertwig’s constrained frog egg
What has changed in our understanding of this basic process?
Ouline
1- A historical view on the question
2- The steps of cell divison
3- Microtubule forces
4- Some classical case studies
5- Predicting division position and orientation
The Different steps of cell division
Animal cells
Plant cells
Metaphase
Anaphase
Cytokinesis
The mitotic spindle
Microtubules
DNA
In animal cells mitotic spindle organises both karyokinesis and cytokinesis
Astral Microtubules play a key role in mediating position and orientation of spindle
Ouline
1- A historical view on the question
2- The steps of cell divison
3- Microtubule forces
4- Some classical case studies
5- Predicting division position and orientation
Microtubules are dynamic
Tubulin-GFP in fission yeast
Microtubules are polarized
Microtubules can generate forces
Minus-end motors: Dynein, kinesin-14
Depolymerizing factors: kinesin-13, kinesin-8
Dominant modes of force generation
Dominant modes of force generation
MT pushing and the problem of cell size
fPush ~ 1/L^2
Sufficient for small cells (fission yeast..~5mic)
Not sufficient for large cells (eggs ~100-1000mic)
Dominant modes of force generation
MT pulling at the cortex
Pulling may be unstable in centering
fpull~ Constant
Pulling with a limiting numbers of sites works in centering
fpull~ L^2
Grill et al. Dev Cell 2005, Wuhr et al. Curr Biol 2009
Dominant modes of force generation
MT pulling in the cytoplasm
fpull~ L
Cytoplasmic forces:
Dynein-mediated vesicle friction?
Wuhr et al. Curr Biol 2009, Kimura et al. 2011
Mechanics of spindle positioning
Microtubules / DNA / Centrosomes
(C. elegans zygote, P. Gonczy Lab)
Microtubules generate forces to position the centrosomes, nuclei or spindle
Forces are biased by different cues : Polarity components, cell adhesion, geometry
Ouline
1- A historical view on the question
2- The steps of cell divison
3- Microtubule forces
4- Some classical case studies
5- Predicting division position and orientation
Asymetric divisions
?
Asymmetric first division in C. elegans embryo
Hyman Lab Youtube Channel
Direct evidence for asymmetric force generation
Grill et al. Nature 2001, Science 2003
Asymmetric first division in C. elegans embryo
Asymmetry in polarity factors lead to
asymmetry in pulling forces exerted by astral
microtubules.
Microtubule pulling forces are exerted by
minus end directed motors (Dynein) that pull
on microtubules
-> position spindle
Morin and Bellaiche, Dev cell 2011
Other Asymmetric classical divisions
S. Cerevisiae
Drosophila Neuroblast
Symetric divisions
?
A-The fission yeast cell
WT
Chang et al. JCS, 1997; Padte et. al. Curr Biol 2006; Celton-Morizur et. al. JCS 2006
The fission yeast cell
Mid1 mutant
Mid1-GFP
WT
Mid1 links Nuclear positioning to cytokinesis
Chang et al. JCS, 1997; Padte et. al. Curr Biol 2006; Celton-Morizur et. al. JCS 2006
The fission yeast cell
Centrifuge nucleus
Without MTs
How is the nucleus position in the center??
Tran et. al., JCB 2001 Daga et al. PNAS 2005, Curr Biol 2006
B. Cell shape and cell division positioning
Observation of cleavage
planes in early embryogenesis
“The two poles of the division figure come to lie
in the direction of the greatest protoplasmic mass”.
(Hertwig, 1884 )
How does it work?
Model system: Sea Urchin embryos
- Round and apolarized
- Large cells/ large organelles
- Cells obtained in large batch
Hoechst staining (DNA)
Time in minutes after fertilization
b. Cell shape and cell division
100mm
Minc et al, Cell, 2011
b. Cell shape and cell division
How does the cell sense its shape? How does the cell define its center/ its geometry?
Interphase microtubules sense shape and orient division
DNA
Microtubules
+ DMSO
+ Nocodazole
. Division axis is set early in interphase/early prophase
. Centering and orientation is MT dependent and actin independent
. MT asters probe cellular space and orient the nucleus by exerting pulling forces
Theoretical model of division axis definition
Key hypothesis: Each MT pulls with a force that scales with its length.
Hamaguchi, Hiramoto, 1980
Wühr , Tan, Parker, Detrich, Mitchison , 2010
Theoretical model of division axis definition
Key hypothesis: Each MT pulls with a force that scales with its length.
Division axis angle, a
Probability density (A.U.)
Torque (A.U.)
=> Compute global torque exerted by the two MT asters on the nucleus
Division axis angle, a
See Théry M, Jiménez-Dalmaroni A, Racine V, Bornens M, Jülicher F., Nature 2007
Experiments
Theory
Theoretical model of division axis definition
All parameters fixed, only cell shape varies
Ouline
1- A historical view on the question
2- The steps of cell divison
3- Microtubule forces
4- Some classical case studies
5- Predicting division position and orientation
Predicting spindle orientation in an adult tissue
Section drawing
from pigeon testis
(M. Guyer, 1900)
Predicting spindle orientation in an adult tissue
Section drawing
from pigeon testis
(M. Guyer, 1900)
Predicting spindle orientation in an adult tissue
Section drawing
from pigeon testis
(M. Guyer, 1900)
Model
Suggest that cell geometry may be a major cue for division positioning in these cells
Predicting cleavage plane orientation
Carvhalo et. al. Nat Cell Biol 2013 (with C-P Heisenberg)
Predicting cleavage plane orientation
Carvhalo et. al. Nat Cell Biol 2013 (with C-P Heisenberg)
Predicting division orientation in tissues
Drosophila thorax
epithelium
Bosveld et al., Submitted, (with Y. Bellaiche)
Continuing projects : Predicting embryonic cleavage patterns
Sea Urchins
Frogs
- Cleavage patterns are stereotyped and invariant among groups of species (amphibians, fishes..)
- Set by various signals (cell shapes, maternal cues, yolk..)
- Yet they are labile, suggesting they may rely more on self-organization designs than determinism
Novel model framework to predict cleavage patterns
1- Model to predict division position in 3D ; can account for surface cues, yolk..
Anaëlle
Novel model framework to predict cleavage patterns
1- Model to predict division position in 3D ; can account for surface cues, yolk..
Anaëlle
2- Model to predict blastomere shapes and
Rearrangements (Surface evolver)
Novel model framework to predict cleavage patterns
F
Polarity cap,
Yolk gradient
Surface
Evolver
3D di vision
model
Shape
Surface
Evolver
Division : volumes and
initial cell-cell contacts
And so on…
Complete in silico modeling of embryos development !
Shapes
Predicting cleavage patterns
Zebrafish
Kimmel et al. 1995
Blastodisc
Predicting cleavage patterns
WT Zebrafish Yolk
A
Model
B
Zebrafish
Blastodisc
Yolk
Hypothesis: Microtubule length-dependent forces
Blastodisc
Predicting cleavage patterns
WT Zebrafish Yolk
A
Blastodisc
Model
B
Zebrafish
Yolk
Top view
Blastodisc
Predicting cleavage patterns
WT Zebrafish Yolk
A
Model
B
Zebrafish
Blastodisc
Yolk
Experiment (Olivier et al., 2010)
C
Top view
Experiment (Olivier et al., 2010)
Model
F
Top view
C
D
Model
F
G
Top view
Side view 1
Top view
Side view 1
Switch of orientation
E
D
Side view 1
G
D
Side view 1
Side view 2
Side view 1
Side view 1
L
H
Side view 2
G
Side view 1
Experiment (Urven et al., 2006)
Switch of orientation
Switch of orientation
Predicting cleavage patterns
A
B
WT xenopus
Yolk granules MTs
Hypothesis: Microtubules pull with length dependent forces,
and are less stable in yolk
C
Model
Xenopus
Predicting cleavage patterns
D
h
Experiment (*)
H
Model
AVCR = H/h
* Yokota et al., 1992
1
2
3
Predicting cleavage patterns
Sea urchin
Macromeres
Micromeres
Take Home
- Division positioning and orientation relies on forces and torques exerted by
cytoskeletal elements onto nuclei or spindles
- These forces are influenced by different cues: Internal polarity, cell geometry, adhesion..
- These cues may act in additive manner in tissues to generate the wide diversity of
division patterns.
- Integration between biological and quantitative approach at the heart of these questions
Acknowledgments
Morphogenetic puzzle team
Collaborators
Arezki Boudaoud, ENS Lyon
Etienne Couturier, MsC, Paris
Carl Philipp Heisenberg, IST, Vienna
Yohanns Bellaiche, Curie, Paris
Alex Mc Dougal, Villefranche
David Burgess, Boston College
Fred Chang, Columbia University
Past members: Francois Rousset, Henry De Belly,
Marguerite Lapierre Yonatan Zegman,
Alexis Campetelli, Rima Seddiki
OPEN POSITIONS FOR MASTERS
IJM
Paris
100m
10m
Armin
10cm
Pombe
10μm