Accueil du site > Animations Scientifiques > Séminaires 2010 > Gijsje Koenderink — Active self-organization of the actin cytoskeleton driven by molecular motors
Gijsje Koenderink — Active self-organization of the actin cytoskeleton driven by molecular motors
Speaker :
Gijsje Koenderink, Biological Soft Matter Group, FOM Institute for Atomic and Molecular Physics (AMOLF), Amsterdam
When :
Wednesday 7 April at 11h
Where :
C023 (RDC LR6 côté Centre Blaise Pascal)
Title :
Active self-organization of the actin cytoskeleton driven by molecular motors
Abstract :
The aim of the Biological Soft Matter group at AMOLF is to understand the physical mechanisms that govern the (active) mechanics of cells. We study in parallel two different model systems of cells. The first approach is to reconstitute artificial cells from purified cytoskeletal proteins inside cell-sized PDMS microchambers or inside liposomes. We can thus dissect the roles of polymer physics, motor proteins, and active filament (de)polymerization. The second approach is to reconstitute artificial tissues by growing cells inside simplified extracellular matrices (collagen or fibrin gels), to study mechanosensing and mechanotransduction. Key technologies are optical microscopy and quantitative image analysis, optical tweezer manipulation, and rheology. In my seminar I will focus on the active self-organization of contractile actin-myosin 2 networks. Myosin II motors assemble into bipolar filaments that slide polar actin filaments (F-actin) past each other as they walk to their plus end. We systematically adjust the myosin activity and processivity and the level of crosslinking, to find out how molecular parameters change the emergent properties (structure and mechanics) of the model cytoskeleton. We show with fluorescence microscopy that the motors generate ring-like actin structures whose size and shape depends both on motor and crosslink density. Myosin accumulates at the center of the actin rings, at the plus ends of the actin filaments, leading to polarity sorting of the actin filaments. Increasing crosslink density enhances the network connectivity and thereby increases the contractility of the network, eventually leading to macroscopic gel contraction. The structure and contractile dynamics in the reconstituted system closely resemble observations in vivo. Using these data, we are starting to build a model relating motor activity on a molecular scale to whole-cell organization and mechanics.
Dans la même rubrique :
- Olivier Gandrillon — A system’s biology approach to understand stochasticity in gene expression
- François Graner — Dynamique des matériaux cellulaires : l’exemple des mousses
- Eric Clément —
- Jacques Pecreaux — Doing the spindle rock. Mitotic spindle motion in C elegans one-cell embryo.
- Arach Goldar — Measuring the time dependent rate of replication origin activation in a single {Saccharomyces cerevisiae} cell by using population dynamics
- M. Carmen Romano — Traffic dynamics of translation : modelling the synthesis of proteins
- Antonin Morillon — Regulatory non coding (nc)RNA and epigenetic in yeast
- Michael Lässig — Molecular evolution in fitness landscapes and seascapes
- Ala Trusina — Defining Network Topologies that Can Achieve Biochemical Adaptation
- George Reid —
- Malcolm Buckle — Etude cinétique et dynamique des complexes macromoléculaires impliquées dans la régulation de l’expression génique par la résonance des plasmons de surface
- Anne-Marie Tassin — Procentriole assembly revealed by cryo-electron tomography
- André Estévez-Torres — Synthetic epigenetics : Sequence-independent photocontrol of gene expression in vitro
- Olivier Cuvier — Deciphering the Discrete Stages of Insulator-encoded Nucleosome-Positioning : The Road towards Transcriptional Competence
- Nick Gilbert — Effect of DNA supercoiling on chromatin structures
- Aurélien Rappailles — Genome wide study of Human DNA replication
- Christophe Lavelle — Chromatin : the DNA manager (and vice versa)
- Michelle D. Wang — DNA Accessibility in Nucleosomes
- Oliver Rando — Fungal chromatin dynamics : from 15 minutes to one billion years
- Shixin Ye — Application of site-directed mutagenesis with unnatural amino acids in studies of G protein-coupled receptors