Biochemical and biological characterization of a neuroendocrine-associated phosphatase.
The biochemical and biological properties of a novel neuroendocrine-associated phosphatase (NEAP) were characterized. NEAP had a sequence characteristic of a dual-specificity phosphatase (DSP), and was preferentially expressed in neuroendocrine cells/tissues as well as in skeletal muscle and heart. Expression of NEAP was up-regulated in nerve growth factor (NGF)-treated, differentiated PC12 cells. NEAP was cytosolic and did not apparently have effects against extracellular signal-regulated kinase, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase activated by various stimuli. Although NEAP and MAPK phosphatase (MPK)-1 showed similar phosphatase activity towards p-nitro phenylphosphate (pNPP), in contrast to MKP-1, NEAP did not dephosphorylate JNK and p38-MAPK in vitro. Overexpression of NEAP, but not the C152S mutant, in PC12 cells suppressed NGF-induced phosphorylation of the p85 subunit of phosphatidylinositol 3-kinase (PI3K) and Akt activation. Overexpression of NEAP also suppressed neurite outgrowth induced by NGF and sensitized PC12 cells to cisplatin-induced apoptosis. Suppression of NEAP by RNA interference enhanced NGF-induced neurite outgrowth and Akt activation. Our results indicated that, unlike other DSPs, down-regulation of conventional MAPKs was not the major function of NEAP. Furthermore, NEAP might be involved in neuronal differentiation via regulation of the PI3K/Akt signaling.
Wang
Jiz-Yuh
JY
Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan Town, Taiwan.
Lin
Chia-Hua
CH
Yang
Chi-Hwa
CH
Tan
Tse-Hua
TH
Chen
Yi-Rong
YR
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002458:Cell Fractionation / Q000379:methods; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D054637:Dual-Specificity Phosphatases; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D054639:Mitogen-Activated Protein Kinase Phosphatases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009154:Mutation / Q000502:physiology; D020932:Nerve Growth Factor / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009490:Neurosecretory Systems / Q000166:cytology / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D016415:Sequence Alignment / Q000379:methods; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014162:Transfection / Q000379:methods
D012333:RNA, Messenger; D020932:Nerve Growth Factor; D020928:Mitogen-Activated Protein Kinases; D054639:Mitogen-Activated Protein Kinase Phosphatases; D010744:Phosphoric Monoester Hydrolases; C500883:DUSP26 protein, human; D054637:Dual-Specificity Phosphatases