The formation of cytoplasmic stress granules upon oxidative stress requires the retrograde motor dynein

LOSCHI, MARIELA,; NEDA BERARDONE; BOCCACCIO, GRACIELA L.

Los Cocos, Córdoba , Argentina

Congreso; VIII Taller Argentino de Neurociencias,; 2006

The formation of cytoplasmic stress granules upon oxidative stress requires the retrograde motor dynein. Loschi, Mariela, Neda Berardone and Boccaccio, Graciela L. Fundación Instituto Leloir, IIBBA-CONICET; FBMC- FCEyN-University of Buenos Aires, ANPCyP. mloschi@leloir.org.ar    Cellular stress is a major player in several neurodegenerative diseases that affect myelin and axons of the central nervous system. This may be provoked by extracellular factors, as in inflammatory conditions, or by intracellular causes, such as the presence of misfolded proteins. As in other cell types, the oligodendrocyte response to stress involves the transient shutting down of normal protein synthesis. We have recently reported that upon stress, the silenced translational apparatus, normally located in the myelinating processes, redistributes to the cell soma and branching points, forming structures ultimately identified as Stress Granules (SGs) (Thomas et al., MBC 2005).  We have monitored the SG formation in fibroblast cell lines by real time confocal microscopy using fluorescent- tagged constructs of SG marker proteins. The process is initiated with the formation of fast-moving small aggregates that then coalesces into perinuclear, large SGs, which remain highly dynamic in size and shape. During recovery, the processes is reverted and SG disolves.  The identity of the motor molecules involved in the movement of the disassembled translational apparatus under stress and in the recovery of its normal distribution after stress release is unknown.  To evaluate the role of the distinct cytoskeleton fibres, we tested the effect of microtubule and microfilament-disrupting drugs on SG formation. We found that the absence of cytoskeletal structures affects the kinetics of SG assembly, their size and distribution. To evaluate the role of the retrograde motor dynein, the effect of transfected dominant negative constructs was analyzed. Overexpression of the motor subunit p50/dynamitin dramatically reduced the proportion of cells bearing SGs. How the dynein-based retrograde transport is activated upon stress remains to be investigated.   Supported by NIH and Wadsworth Foundation (USA), Fundación Antorchas, FLENI  and ANPCyT (Argentina).