Biomedical subjects

Nir S Gov

Publications and source records attributed to Nir S Gov.

4 recordsLinked to original sources

PubMed2006

Modeling the size distribution of focal adhesions.

We calculate the size distribution of two-dimensional aggregates, for different simple dynamical growth models. The resulting size distributions of these domains, at steady state, are shown to depend strongly on the mode of domain growth. We then compare to the measured size-distribution of focal-adhesion domains. Using our calculation and the measured exponential distribution of focal-adhesion domain lengths can be used to test the validity of recent models proposed to describe the dynamics of these complexes in adhering cells.

Cell Adhesion↗

PubMed2006

Dynamics and morphology of microvilli driven by actin polymerization.

Many different cell types have dynamic protrusions, called microvilli, on their surface. We model these structures as arising from the balance between the force of actin polymerization and the restoring force of the membrane. From this simple model we calculate the distribution function of microvilli heights for several cells. We further describe the phase diagram and the resulting morphology of the microvilli aggregates on the cell surface.

Actins↗

PubMed2006

Diffusion in curved fluid membranes.

We analyze theoretically the effects of curvature on the diffusion in a fluid membrane, within the Saffman-Delbrück hydrodynamic model. We calculate the effect of curvature on the intrinsic fluidity of a membrane through changes in its thickness, for both static or fluctuating curvature. We treat both thermal curvature fluctuations, and fluctuations due to active processes. Such curvature fluctuations increase the average membrane thickness and diminish the projected area, thereby decreasing the diffusion coefficient. This calculation allows us to predict the effect of shear flow on the membrane diffusion, and to compare to observations on living cells.

Computer Simulation↗

PubMed2005

Dynamics of membranes driven by actin polymerization.

A motile cell, when stimulated, shows a dramatic increase in the activity of its membrane, manifested by the appearance of dynamic membrane structures such as lamellipodia, filopodia, and membrane ruffles. The external stimulus turns on membrane bound activators, like Cdc42 and PIP2, which cause increased branching and polymerization of the actin cytoskeleton in their vicinity leading to a local protrusive force on the membrane. The emergence of the complex membrane structures is a result of the coupling between the dynamics of the membrane, the activators, and the protrusive forces. We present a simple model that treats the dynamics of a membrane under the action of actin polymerization forces that depend on the local density of freely diffusing activators on the membrane. We show that, depending on the spontaneous membrane curvature associated with the activators, the resulting membrane motion can be wavelike, corresponding to membrane ruffling and actin waves, or unstable, indicating the tendency of filopodia to form. Our model also quantitatively explains a variety of related experimental observations and makes several testable predictions.

Actins↗