Phosphoproteome study reveals Hsp27 as a novel signaling molecule involved in GDNF-induced neurite outgrowth.
Glial-cell-line-derived neurotrophic factor (GDNF) is a most potent survival factor for dopaminergic neurons. In addition, GDNF was also found to promote neurite outgrowth in dopaminergic neurons. However, despite the potential clinical and physiological importance of GDNF, its mechanism of action is unclear. Therefore, we employed a state-of-the-art proteomic technique, DIGE (Difference in two-dimensional gel electrophoresis), to quantitatively compare profiles of phosphoproteins of PC12-GFRalpha1-RET cells (that stably overexpress GDNF receptor alpha1 and RET) 0.5 and 10 h after GDNF challenge with control. A total of 92 differentially expressed proteins were successfully identified by mass spectrometry. Among them, the relative levels of phosphorylated Hsp27 increased significantly both in 0.5 and 10 h GDNF-treated PC12-GFRalpha1-RET cells. Confocal microscopy and Western blot results showed that the phosphorylation of Hsp27 after GDNF treatment was accompanied by its nuclear translocation. After the mRNA of Hsp27 was interfered, neurite outgrowth of PC12-GFRalpha1-RET cells induced by GDNF was significantly blocked. Furthermore, the percentage of neurite outgrowth induced by GDNF was also reduced by the expression of dominant-negative mutants of Hsp27, in which specific serine phosphorylation residues (Ser15, Ser78 and Ser82) were substituted with alanine. Our data also revealed that p38 MAPK and ERK are the upstream regulators of Hsp27 phosphorylation. Hence, in addition to the numerous novel proteins that are potentially important in GDNF mediated differentiation of dopaminergic cells revealed by our study, our data has indicated that Hsp27 is a novel signaling molecule involved in GDNF-induced neurite outgrowth of dopaminergic neurons.
Hong
Zhen
Z
Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200025, China.
Zhang
Qun-Ye
QY
Liu
Jun
J
Wang
Zhi-Quan
ZQ
Zhang
Yu
Y
Xiao
Qin
Q
Lu
Jing
J
Zhou
Hai-Yan
HY
Chen
Sheng-Di
SD
D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation; D016000:Cluster Analysis; D015180:Electrophoresis, Gel, Two-Dimensional; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015870:Gene Expression; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000378:metabolism*; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D016501:Neurites / Q000378:metabolism / Q000502:physiology*; D016716:PC12 Cells; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D020543:Proteome / Q000378:metabolism*; D051381:Rats; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D051100:Glial Cell Line-Derived Neurotrophic Factor; D055551:HSP27 Heat-Shock Proteins; D010750:Phosphoproteins; D020543:Proteome; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases