title: SIRT1 knockdown promotes neural differentiation and attenuates the heat shock response.
abstract: Neurons have a limited capacity for heat shock protein (HSP) induction and are vulnerable to the pathogenic consequence of protein misfolding and aggregation as seen in age-related neurodegenerative diseases. Sirtuin 1 (SIRT1), an NAD(+) -dependent lysine deacetylase with important biological functions, has been shown to sustain the DNA-binding state of HSF1 for HSP induction. Here we show that differentiation and maturation of embryonic cortical neurons and N2a neuroprogenitor cells is associated with decreases in SIRT1 expression and heat shock-dependent induction of HSP70 protein. Tests of a pharmacological activator and an inhibitor of SIRT1 affirm the regulatory role of SIRT1 in HSP70 induction. Protein cross-linking studies show that nuclear SIRT1 and HSF1 form a co-migrating high molecular weight complex upon stress. The use of retroviral vectors to manipulate SIRT1 expression in N2a cells show that shRNA-mediated knock down of SIRT1 causes spontaneous neurite outgrowth coincident with reduced growth rate and decreased induction of hsp70-reporter gene, whereas SIRT1 over-expression blocks the induced neural differentiation of N2a cells. Our results suggest that decreased SIRT1 expression is conducive to neuronal differentiation and this decrease contributes to the attenuated induction of HSPs in neurons.
authors.affiliation: Department of Cell Biology and Neuroscience, Rutgers State University of New Jersey, Piscataway, New Jersey.
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Liu
authors.forename: David
authors.initials: D
authors.lastname: Hammer
authors.forename: Daniel
authors.initials: D
authors.lastname: Komlos
authors.forename: Kuang Yu
authors.initials: KY
authors.lastname: Chen
authors.forename: Bonnie L
authors.initials: BL
authors.lastname: Firestein
authors.forename: Alice Y-C
authors.initials: AY
authors.lastname: Liu
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002540:Cerebral Cortex / Q000196:embryology / Q000201:enzymology* / Q000473:pathology; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation; D055785:Gene Knockdown Techniques; D005865:Gestational Age; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D051379:Mice; D058953:Neural Stem Cells / Q000201:enzymology* / Q000473:pathology; D055495:Neurogenesis; D009474:Neurons / Q000201:enzymology* / Q000473:pathology; D011485:Protein Binding; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C490017:Hsf1 protein, mouse; C000619709:Hsf1 protein, rat; D014157:Transcription Factors; C470545:Sirt1 protein, mouse; C488368:Sirt1 protein, rat; D056564:Sirtuin 1