Event & Seminars
Platelets and vascular inflammation
Remodeling of cellular machineries in quiescence.
D. Laporte, L. Gouleme, J. Dompierre, I. Sagot
IBGC – CNRS UMR 5095. 1, rue Camille Saint Saëns. 33077 BORDEAUX cedex.
Each cell individually integrates a combination of external and internal signals before committing to another round of cell division. If these signals are not favorable to proliferation, cells exit the division cycle and may enter quiescence, a reversible non-dividing cellular state. Quiescence establishment and exit are therefore key steps involved in major human pathologies like cancers, but also in fundamental biological processes such as development, aging and evolution. Despite its crucial impacts on human health, quiescence remains poorly understood.
Using S. cerevisiae and S. pombe, two evolutionary distant unicellular eukaryotes, as model organisms, we have pioneered the characterization of quiescent cells at the individual cell level. Within the last years, we have demonstrated that upon quiescence establishment, yeast cells remodel various cellular machineries and assemble original cellular structures. Indeed, the actin cytoskeleton is drastically reshaped and forms Actin Bodies, structures composed of stable F-actin filaments. The proteasome is re-localized from the nucleus into cytoplasmic particles that we have called Proteasome Storage Granules. The microtubule cytoskeleton is completely remodeled, and form a unique bundle of very stable microtubules associated with the spindle pole body, the yeast equivalent of the centrosome. Finally, the mitochondrial network is entirely redesigned and its organization can be used to predict individual cell fate upon aging.
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