title: Roles of autophagy and mTOR signaling in neuronal differentiation of mouse neuroblastoma cells.
abstract: Cell differentiation is often associated with decreased cell growth, indicating an altered rate of macromolecule synthesis and degradation. In this study, we present evidence that autophagy, a process for bulk degradation of cytoplasm, is activated during retinoic acid-induced neuronal differentiation of neuroblastoma N2a cells. Chemical inhibitors of autophagy, including 3-MA and LY294002, abrogate cell differentiation. RNA interference of autophagy gene beclin 1 markedly delays the process of differentiation. We also find that cell differentiation is accompanied by decreased activity of mTOR, a major controller of cell growth and a negative regulator of autophagy. However, completely inhibiting mTOR by rapamycin decreases neurite outgrowth, cell size and the immunoreactivity for neuronal markers. Our study suggests that an appropriate level of mTOR activity is important in cell differentiation for a balance between macromolecule synthesis and degradation.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026, PR China.
authors.forename: Mei
authors.initials: M
authors.lastname: Zeng
authors.forename: Jiang-Ning
authors.initials: JN
authors.lastname: Zhou
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001343:Autophagy / Q000187:drug effects / Q000235:genetics; D000071186:Beclin-1; D002352:Carrier Proteins / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D048429:Cell Size; D002867:Chromones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D016501:Neurites / Q000378:metabolism / Q000473:pathology; D009447:Neuroblastoma / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D013997:Time Factors; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; C115010:Becn1 protein, mouse; D002352:Carrier Proteins; D002867:Chromones; D009025:Morpholines; D011506:Proteins; D034741:RNA, Small Interfering; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C025946:3-methyladenine; D014212:Tretinoin; D011494:Protein Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); C546843:mTOR protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D000225:Adenine; D020123:Sirolimus