Inhibition of the nerve growth factor-induced outgrowth of neurites by trichostatin A requires protein synthesis de novo in PC12D cells.
Trichostatin A (TSA) inhibits the activity of histone deacetylase and blocks both oncogenic ras-induced and nerve growth factor-induced (NGF-induced) outgrowth of neurites from PC12 cells. Cells of the PC12D subline extend neurites very rapidly in response to NGF, basic fibroblast growth factor (bFGF), dibutyryl cAMP (dbcAMP) and to staurosporine, even in the presence of an inhibitor of RNA synthesis, as do primed PC12 cells or cultured sympathetic neurons. TSA at 100 nM selectively blocked the NGF- and bFGF-induced outgrowth of neurites from PC12D cells, but not the outgrowth induced by dbcAMP or staurosporine. The NGF-induced changes in morphology with the relocalization of F-actin, were not inhibited by TSA. However, the subsequent formation of growth cones and the outgrowth of neurites was blocked. The activation of mitogen-activated protein (MAP) kinases in NGF-stimulated cells was also unaffected by TSA. When TSA was added to cells that were extending neurites in response to NGF, the number of neurite-bearing cells decreased after a lag period. In the presence of inhibitors of RNA or protein synthesis namely, actinomycin D, cordycepin, and cycloheximide, TSA no longer blocked the NGF- and bFGF-dependent outgrowth of neurites from PC12D cells. Regardless of the effect of TSA, the rapid outgrowth of neurites from PC12D cells was unaffected by the presence of cycloheximide, which inhibited protein synthesis by 97%, as determined by monitoring the incorporation of [35S]methionine/cysteine. This study provides proof that the NGF-induced elongation of neurites does not require protein synthesis de novo. These observations suggest that TSA might not inhibit the early signal-transduction pathway of NGF, but might block the late pathway, which is related to the formation of growth cones and/or neurites. Cellular conditions that no longer allow the NGF- and bFGF-mediated elongation of neurites might be produced by TSA via synthesis of some specific protein(s) due to changes in RNA(s) synthesis de novo.
Sano
M
M
Institute for Developmental Research, Aichi Human Service Center, Kamiya-cho, Kasugai, Japan.
Kitajima
S
S
D000818:Animals; D002452:Cell Count / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006877:Hydroxamic Acids / Q000494:pharmacology*; D009414:Nerve Growth Factors / Q000494:pharmacology*; D016501:Neurites / Q000187:drug effects*; D016716:PC12 Cells / Q000187:drug effects; D011506:Proteins / Q000187:drug effects* / Q000378:metabolism; D051381:Rats
D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D009414:Nerve Growth Factors; D011506:Proteins; C012589:trichostatin A