Ubiquitin and ubiquitin-protein conjugates in PC12h cells: changes during neuronal differentiation.
Ubiquitin and ubiquitin-protein conjugates in PC12h cells were detected with in vitro [125I]ubiquitination, and quantified by immunoblotting. These levels were altered by nerve growth factor (NGF), which promotes neuronal differentiation. (i) Levels of high molecular weight (HMW) ubiquitin-protein conjugates ranging from 40 to 1,000 kDa were increased by 2 days of NGF treatment, and remained high up to 10 days of NGF treatment. (ii) Ubiquitin and a 23-kDa conjugate tended to be decreased from days 2 to 10 of NGF treatment. 10-Day culture with 10 nM staurosporine, n protein kinase inhibitor, that blocks NGF-induced neurite outgrowth suppressed the NGF-induced increases in levels of HMW conjugates. Cyclic AMP and forskolin, both of which promote neurite outgrowth, mimicked the NGF-induced changes in ubiquitin and HMW conjugates, but phorbol ester and epidermal growth factor had little effect. These findings suggest that changes in ubiquitin-protein conjugates are closely coupled with neuronal differentiation.
Takada
K
K
Department of Research Laboratory, SRL, Inc., Tokyo, Japan.
Kanda
T
T
Ohkawa
K
K
Matsuda
M
M
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002454:Cell Differentiation; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D007457:Iodine Radioisotopes; D008970:Molecular Weight; D009414:Nerve Growth Factors / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D016716:PC12 Cells; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011498:Protein Precursors / Q000302:isolation & purification / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000302:isolation & purification / Q000378:metabolism*; D019311:Staurosporine; D014452:Ubiquitins / Q000302:isolation & purification / Q000378:metabolism*
D000470:Alkaloids; D007457:Iodine Radioisotopes; D009414:Nerve Growth Factors; D011498:Protein Precursors; D012269:Ribosomal Proteins; D014452:Ubiquitins; D011493:Protein Kinase C; D019311:Staurosporine