EFFECTS OF A DECREASE ON THE PROTEASOME ACTIVITY IN THE EXPRESSION OF MBP RNAm.

MOIOLA C, SOTO E, PASQUINI J, PASQUINI LA

Pinamar, Buenos Aires, Argentina

Congreso; SAIB -PABMB-SAN; 2005

Sociedad Argentina de Neuroquimica

We have demonstrated that the addition of Lactacystin (L), an specific inhibitor of the 26S proteasome, to oligodendrocytes (OLG) cultures induce their exit from the cell cycle and differentiation. Recent studies demonstrated that a decrease in proteasome activity enhances the MBP promoter in N20.1 OLGc line, due to a stabilization of Sp1 and p27. Results in Swiss male mice intracraneally injected (ICI) in corpus callosum with L at day 5-7 post-birth and evaluated 7 days after, showed an increase in myelin deposition, total proteins, myelin galactolipids and in the different isoforms of MBP related to control. We have decided to evaluate consequences in MBP RNAm expression by the decrease in the proteasome activity “in vivo” during normal myelination. Mice were sacrificed at day 7, 9, 11, 13 post-birth and their brains dissected to make a total RNA isolation, PCR, semi quantitative PCR and Northern Blot. Measured levels of the MBP RNAm show a good correlation with animal age and normal myelination parameters. Supporting this, we found that Sp1 RNAm levels are diminished in L, possibly explained by the stabilization of Sp1 protein degradation by proteasome inhibition.  We expect to demonstrate a correlation between the accelerated myelination previously demonstrated in animals ICI with L and the MBP RNAm levels compared to control.