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Etalement de Dictyostelium discoideum et rôle des protéines Phg2, PKD2 et TPC dans la motilité.

Abstract : Dictyostelium discoideum is a unicellular eukaryote with abilites to crawl on surfaces and feed on bacteria. It is widely used as a model for chemotaxis and cell motility. In our laboratory, S.Fache showed that the motility of Dictyostelium is enhanced by shear stress, and that the maximal speed depends on extracellular calcium concentration.
In this work, we have studied the spreading of Dictyostelium on a surface. This process is similar to the first step of cell motility. We have shown that Dictyostelium spreading is quasi-linear and anisotrope. Furthermore, we have discovered a periodic activity in the speed of gain and loss area during spreading. The molecular origin of this activity is unknown.
These works on cellular spreading enable us to characterize the function of the protein Phg2 during cell motility. Phg2 is a kinase involved in phagocytosis and motility. We have established that Phg2 controls cell polarity through it's Ras Binding Domain. Phg2 also controls local actin polymerisation through it's kinase domain.
Finally, we knocked out two genes coding for potential calcium channels in Dictyostelium.
The studies we have led with the mutant cells suggest that they are not involved in the calcium response during shear stress induced cell motility.
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Contributor : Sébastien Keller <>
Submitted on : Friday, November 30, 2007 - 11:04:23 AM
Last modification on : Friday, November 6, 2020 - 3:44:56 AM
Long-term archiving on: : Monday, April 12, 2010 - 5:36:18 AM

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  • HAL Id : tel-00193002, version 1

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Sébastien Keller. Etalement de Dictyostelium discoideum et rôle des protéines Phg2, PKD2 et TPC dans la motilité.. Biologie cellulaire. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00193002⟩

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