Dynamic association of Rpt5 to cold-stable microtubules in glial cells

BONNET LV; GALIANO MR; FLORES MARTIN J; HALLAK ME; PALANDRI A

Cordoba

Congreso; XXXIV Reunión de la Sociedad Argentina de Investigación en Neurociencias (SAN); 2019

Sociedad Argentina de Investigación en Neurociencias (SAN)

The ubiquitin-proteasome system (UPS) is a key cellular complex devoted to proteostasis maintenance. Alterations of its proteolytic activity are closely linked to pathogenesis of cancer or neurodegenerative disorders. Two main complex conform the 26S proteasome, the regulatory particle 19S proteasome and 20S complex. Different reports showed the impairment of proteasomal activity induced by stress conditions. Our study was aimed to analyze how are affected the UPS in glial cells exposed to cold temperature. As expected, a strong reduction on 20S proteasome activity was determined by enzymatic assay and it was detected an increase polyubiquitinated proteins by western blot, indicating a reduction in the activity of the UPS complex under cold condition. By immunofluorescence we observed a clear redistribution of Rpt5 (subunit of 19S complex) associated to a subpopulation of cold stable microtubules (Mts) but, no apparent changes on cellular distribution of 1-7 subunitsof 20S was observed in Schwann cells, astrocytes or oligodendrocytes exposed to cold temperature. We also found that this association of Rpt5 to Mts is reversible and specific of this subunit. Biochemical evidences of Rpt5/MAP6/tubulin interactions were found from immunoprecipitation assays. Hence, the association of Rpt5 to Mts, may have physiological significance controlling Rpt5 function as part of the proteasome regulatory particle in glia cells.