Ongoing DNA synthesis in the rat cerebral cortex is regulated by a proteolytic pathway independent of the proteasome and calpains.
By using mini-units of tissue and protease inhibitors in short term incubation (0-180 min), we studied the role of proteolysis for ongoing DNA replication in the developing rat cerebral cortex. The protease inhibitors TLCK, TPCK, PMSF, MG-132 and PSI markedly inhibited DNA synthesis. The inhibitory effects were concentration-dependent and of early onset (within 60 min). The most selective proteasome inhibitors lactacystin and clasto-lactacystin-beta-lactone as well as the calpain inhibitor I and II had no or minimal effects on DNA synthesis. Only high concentrations of calpain inhibitor I (>or= 250 microM) and calpain inhibitor II (>or= 500 microM) gave a DNA synthesis inhibition. These results suggest that (1) ongoing DNA replication is regulated by proteolysis and (2) the proteolytic pathways involved are neither the proteasome nor the calpains.
Yakisich
J Sebastián
JS
Department of Clinical Neuroscience, Huddinge Division of Neurology, Karolinska Institute, Huddinge University Hospital, 141 86 Huddinge, Sweden. Sebastian.Yakisich@ki.se
Sidén
Ake
A
Cruz
Mabel
M
D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*
D015853:Cysteine Proteinase Inhibitors; D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D015842:Serine Proteinase Inhibitors; D004247:DNA; D046988:Proteasome Endopeptidase Complex