Involvement of protein kinase C and E2F-5 in euxanthone-induced neurite differentiation of neuroblastoma.
Euxanthone, a neuritogenic agent isolated from the medicinal herb Polygala caudata, has been shown to induce morphological differentiation and neurite outgrowth in murine neuroblastoma Neuro 2a cells (BU-1 subclone). In order to elucidate the underlying mechanisms of euxanthone-induced neurite outgrowth, a proteomic approach was employed. In the present study, two dimensional (2-D) gel electrophoresis and matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) mass spectrometry were performed to investigate the alterations in protein expression profile of euxanthone-treated BU-1 cells. Fourteen identified proteins were changed in expression levels after induction of neurite growth. These proteins included participants in transcription and cell cycle regulation, calcium influx and calcium signaling, fatty acid metabolism, cytoskeleton reorganization, casein kinase signal transduction, putative transbilayer amphipath transport and protein biosynthesis. Among the 14 identified proteins, E2F transcription factor 5 (E2F-5) was significantly up-regulated after euxanthone treatment. Go6976, a protein kinase C (PKC) alpha/betaI inhibitor, was found to inhibit neuritogenesis and expression of E2F-5 in the euxanthone-treated BU-1 cells, while SH-6, the Akt/PKB inhibitor, had no inhibitory effect. The gene silencing of E2F-5 by small interfering RNA (siRNA) was found to abolish the euxanthone-induced neurite outgrowth. In conclusion, these results indicated that the transcription factor E2F-5 was actively involved in the regulation of euxanthone-induced neurite outgrowth via PKC pathway.
Ha
Wai Yan
WY
Research and Development Division, School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China.
Wu
Pui Kei
PK
Kok
Tsz Wai
TW
Leung
Kar Wah
KW
Mak
Nai Ki
NK
Yue
Patrick Ying Kit
PY
Ngai
Sai Ming
SM
Tsai
Sau Na
SN
Wong
Ricky Ngok Shun
RN
D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D050684:E2F Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D020868:Gene Silencing; D007211:Indoles / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D040901:Proteomics / Q000379:methods; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D044004:Xanthones / Q000494:pharmacology*
D002227:Carbazoles; D050684:E2F Transcription Factors; D007211:Indoles; D047428:Protein Kinase Inhibitors; D044004:Xanthones; C081021:Go 6976; C404221:euxanthone; D051057:Proto-Oncogene Proteins c-akt; D011493:Protein Kinase C