Inhibition of the proteasome by lactacystin enhances oligodendroglial cell differentiation.
We have used lactacystin, a specific inhibitor of the 26S proteasome, in oligodendroglial cell (OLGc) primary cultures to explore the possible participation of the proteasome-ubiquitin-dependent pathway in the decision of the OLGcs to arrest their proliferation and start differentiation. Addition of lactacystin at various concentrations to cultures containing a majority of OLGc was found to produce their withdrawal from the cell cycle and to induce their biochemical and morphological differentiation, with the appearance of extensive myelin-like sheets. The three classic proteolytic activities of the proteasome were significantly decreased in the lactacystin-treated cultures, and the immunocytochemical analysis showed an increase in the number of O4-, O1-, myelin basic protein-, and myelin proteolipid protein-positive cells and a decrease in A2B5-reacting cells. Quantitative immunochemical evaluation of the expression of certain proteins controlling the cell cycle showed an increase in p27kip1-, cyclin D-, and cdk4-positive cells, with a decrease in cyclin E- and cdk2-positive cells. In the lactacystin-treated OLGcs, there was a dose-dependent decrease in the number of cells incorporating bromodeoxyuridine and in the activity of the complexes cyclin D-cdk4 and cyclin E-cdk2. Furthermore, increased levels of expression of several STAT factors were found, suggesting that proteasome inhibition in OLGcs could stabilize signals of survival and differentiation that might be processed through the JAK/STAT signaling cascade.
Pasquini
Laura A
LA
Departamento de Química Biológica, Instituto de Química y Fisicoquímica Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires 1113, Argentina.
Paez
Pablo M
PM
Moreno
Marcos A N Besio
MA
Pasquini
Juana M
JM
Soto
Eduardo F
EF
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D001973:Bromodeoxyuridine; D018797:Cell Cycle Proteins / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007150:Immunohistochemistry; D007976:Leupeptins / Q000494:pharmacology; D046911:Macromolecular Substances; D009836:Oligodendroglia / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D010447:Peptide Hydrolases / Q000187:drug effects* / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects
D018797:Cell Cycle Proteins; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D046911:Macromolecular Substances; C067713:lactacystin; D018844:Cyclin-Dependent Kinases; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D001973:Bromodeoxyuridine; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D000111:Acetylcysteine