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Topic Name: Cellular division, the Signal “models” cells
Category: Biodesign
Research persons: Andrea Jiménez-Dalmaroni,Victor Root , Michel
Location: Max Planck Society, Munich, Germany
Details
Division is a key stage of the life of the cells which brings
into play a very great number of molecular actors and a complex dynamics. While
collaborating, the biologists of CNRS at the Institute Curie and the physicists
theorists of the max Planck in Germany, developed an ideal model of the cellular
division of a great predictive value. The recourse to microphone-technologies
makes it possible individually to study the division of cells according to the
variations of their environment. From their observations on a very great number
of cells, the researchers describe a predictive ideal model of the orientation
of the cellular division. This model, based on the calculation of the forces
which are exerted on the spindle mitotic inside the cell, described in the
Nature review of May 24, 2007, accounts for the good course or the dysfunction
of the division of a cell. In addition, this model made it possible to show that
certain configurations of microenvironnment are able to induce the asymmetrical
division of the cells. Applied to fabrics, it will make it possible to refine
the diagnosis by describing the disordered states of divisions of the
pathological cells.
Division
is an essential stage of the life of any cell: it takes part in the growth of
the organization, with repair of wounds or infections and with the normal
replacement of the cells. 250.000 million cells are in the course of division in
our organization at every moment. Each one of it, as of its formation, has a
well determined place. This very precise positioning is essential to maintain
the shape of our fabrics and our bodies. They are the constraints induced by the
other cells, the environment, which influence the division and the positioning
of the cells girls.
Manuel
Théry in team CNRS of Michel Bornens developed an original approach which it
currently continues in the Commissariat à l' Énergie Atomique of Grenoble (1),
to study the influence of space and its constraints on the division of the cells
and more precisely of only one cell: “microphone-stencil key sets” which
impose the same contour on the cell all while providing him zones of different
adhesions, as if it were surrounded by other cells. This microphone-technology
makes it possible to modulate the environment of the cell and to observe its
answer. The imposed constraints reproduce space information that a cell is
likely “to feel” within a fabric.
Collaboration
enters team CNRS of Michel Bornens to the Institute Curie, and that of
theoretical physics of Frank Jülicher, director of the max
Planck Institute for the Physics of Complex Systems in Dresden in Germany,
succeeded, thanks to this microphone-technology, with a modeling of the cellular
division. Measurements of the orientations of cellular thousands of divisions
enabled them to propose a mechanical model of positioning of the spindle
mitotic, transitory cellular structure presents only at the moment of the
cellular division, based on the activation of molecules “engines” on the
surface of the cell. The engines, localised on the level of the points of
contact of the cell with its microphone-environment, draw on the astral
microtubules and direct the spindle. This mechanism makes it possible the cells
to grant the position of the plan of division with the geometry of their
environment.
The
researchers also show that certain space configurations of microenvironnement
cellular induce asymmetrical orientations of the spindle. The division of the
cells in a symmetrical way or not is of primary importance in the destiny of the
cells girls which of it result. These results could thus have interesting
applications in the control of symmetrical or asymmetrical divisions of the
cells in vitro stocks.
Only
the recourse to microphone-technologies as the “microphone-stencil key sets”
makes it possible to study the individual “sensitivity” of a great quantity
of cells to draw some from the laws being able to predict the distribution of
the orientations of division without knowing the detail of the implied molecular
mechanisms. These laws are operational in an embryo or an organization which
renews themselves. One can thus hope in the long term to obtain a description of
mechanics concerned during the development. This mechanics could be not only one
consequence but an active regulator of the genetics implemented in the growth of
fabrics.
It
is thus from now on possible to measure the capacity of a cell to answer its
environment in a quantified and precise way but also to locate the cells which
have an “abnormal” behavior, like the cancerous cells. This model, when it
is exploitable on the level them fabrics, will be able to make it possible to
the doctors to refine the diagnosis by informing them about the disordered
states of division in the pathological cells.
This
work in addition illustrates the interest of the crossing of competences: the
gathering of researchers of different horizons, historical stake at the
Institute Curie, generates an environment dynamic and favorable to the
creativity. One of the great originalities of the Institute Curie in particular
was to develop collaboration between physicists and biologists. This interface
gives another vision of the cellular world extremely promising to
include/understand the complexity of the alive one.
References:
“Experimental and theoretical study of mitotic spindle orientation”
Handbook Théry (1,2), Andrea Jiménez-Dalmaroni (3), Victor Root (1), Michel
Bornens (1,4), Frank Jülicher (3,4)
Nature, May 24, 2007, vol. 447, p. 493-497
1) Institute Curie, CNRS UMR144, Compartmentation and Cellular Dynamics.
2) Commissariat à l' Énergie Atomique, DSV, iRTSV, Laboratory Biochips.
3) Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.
4) Collaboration financed by a contract “Human Frontier Organization
Science” whose coordinator is Michel Bornens
In The Images :
By using the various shapes of “micro stencil key sets” (in red), the researchers observe how are directed the cellular division (line in lower part with in blue, chromosomes and in green, fibres of retraction which maintains connection between the cellular body and the “microphone-stencil key set”). They note that the cell answers in a way adapted to its environment. By multiplying measurements on the orientation of the cellular division, they thus could propose a mechanical model of positioning of the spindle mitotic, transitory cellular structure presents only at the moment of the cellular division
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