Analyzing the role of post-translational protein arginylation in Schwann cells after nerve injury

MAURICIO R. GALIANO; JESICA FLORES-MARTIN; LAURA V. BONNET; MARTA E. HALLAK

Buenos Aires

Simposio; The role of glial cells in health and disease of the Nervous System: Clinical and Basic Science walking together; 2017

SouthAmerican Neuroglia

The role of the arginyl-protein transferase (Ate1) mediating the post-translational arginylation ofproteins has been mainly studied in fibroblasts and muscle cells, however its function amongnervous system components is poorly understood. Previous reports described that posttranslationalarginylation of proteins increased after injury of sciatic nerves whereas Ate1 activitydid not change after optic nerve lesion. Our studies are aimed to determine whether suchdifference is related with whole nerve tissue or corresponds to a particular cell type. Weperformed primary Schwann cell cultures from P8 rats to model peripheral nerve injury. ByWestern blot we found that Ate1 expression reaches a maximum in DIV 5 cultures of Schwann anddecays later on. This variation of Ate1 expression parallels the recently described activation ofautophagy in these cells. Moreover, a similar increase was found for arginylated calreticulin (RCRT),an Ate1 modified protein, which also showed partial colocalization with markers ofautophagy by confocal microscopy. Further analysis of sciatic nerve segments that were culturedunder different conditions showed that the proteasomal inhibitor (MG132) increased Ate1 levels,whereas autophagy inhibition with 3MA did not. As well the progress of myelin degradation getsmore retarded by MG132 than by 3MA. To confirm if increased post-translational proteinarginylation in Schwann cells corresponds to enhanced protein degradation by autophagy afterperipheral nerve injury, new studies are currently performed with Ate1 conditional mutants.Moreover, our model will help to determine how Ate1 activity modulates the crosstalk betweenautophagy and ubiquitin proteasome degradation of proteins.