Proteomic analysis of proteins in PC12 cells before and after treatment with nerve growth factor: increased levels of a 43-kDa chromogranin B-derivedfragment during neuronal differentiation

Proteomic analysis is an important approach to characterizing the proteome and studying protein function in the post-genomic era. It is also a powerfu l screening method for detecting unexpected alterations in protein expressi on that may be missed by conventional biochemical techniques. The aim of th is study was to perform a preliminary proteomic analysis of PC12 cells in o rder to investigate the effect of nerve growth factor (NGF) on protein expr ession in PC12 cells during neurite outgrowth. PC12 cell proteins were sepa rated by two-dimensional electrophoresis (2DE) and visualized by silver sta ining, then certain proteins were identified by N-terminal amino acid micro sequencing and a homology search of a protein sequence database. Over 400 p roteins were detected, 10% of which showed a significant (greater than 30%) increase or decrease in expression during NGF-induced neuronal differentia tion. Seven proteins in the 2DE map were identified; the levels of five of these were unaffected by NGF treatment, whereas the levels of the other two , P-tubulin and a novel 43-kDa chromogranin B-derived fragment, were signif icantly increased by more than 30 and 200%, respectively. Our results sugge st that chromogranin B processing is enhanced in PC12 cells during NGF-indu ced neuronal differentiation. In addition, since this increase in the level s of the chromogranin B-derived fragment was specifically blocked by PD9805 9, we suggest that the increased processing can be ascribed to activation o f the MAP kinase pathway, and that the 43-kDa chromogranin B-derived fragme nt can serve as a new marker of neuronal differentiation for proteomic stud ies. (C) 2001 Elsevier Science BY All rights reserved.