title: Cell cycle-regulated multi-site phosphorylation of Neurogenin 2 coordinates cell cycling with differentiation during neurogenesis.
abstract: During development of the central nervous system, the transition from progenitor maintenance to differentiation is directly triggered by a lengthening of the cell cycle that occurs as development progresses. However, the mechanistic basis of this regulation is unknown. The proneural transcription factor Neurogenin 2 (Ngn2) acts as a master regulator of neuronal differentiation. Here, we demonstrate that Ngn2 is phosphorylated on multiple serine-proline sites in response to rising cyclin-dependent kinase (cdk) levels. This multi-site phosphorylation results in quantitative inhibition of the ability of Ngn2 to induce neurogenesis in vivo and in vitro. Mechanistically, multi-site phosphorylation inhibits binding of Ngn2 to E box DNA, and inhibition of DNA binding depends on the number of phosphorylation sites available, quantitatively controlling promoter occupancy in a rheostat-like manner. Neuronal differentiation driven by a mutant of Ngn2 that cannot be phosphorylated by cdks is no longer inhibited by elevated cdk kinase levels. Additionally, phosphomutant Ngn2-driven neuronal differentiation shows a reduced requirement for the presence of cdk inhibitors. From these results, we propose a model whereby multi-site cdk-dependent phosphorylation of Ngn2 interprets cdk levels to control neuronal differentiation in response to cell cycle lengthening during development.
authors.affiliation: Department of Oncology, University of Cambridge, Hutchison/Medical Research Council Research Centre, Cambridge CB2 0XZ, UK.
authors.forename: Fahad
authors.initials: F
authors.lastname: Ali
authors.forename: Chris
authors.initials: C
authors.lastname: Hindley
authors.forename: Gary
authors.initials: G
authors.lastname: McDowell
authors.forename: Richard
authors.initials: R
authors.lastname: Deibler
authors.forename: Alison
authors.initials: A
authors.lastname: Jones
authors.forename: Marc
authors.initials: M
authors.lastname: Kirschner
authors.forename: Francois
authors.initials: F
authors.lastname: Guillemot
authors.forename: Anna
authors.initials: A
authors.lastname: Philpott
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D002453:Cell Cycle; D002454:Cell Differentiation; D018507:Gene Expression Regulation, Developmental; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008954:Models, Biological; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D055495:Neurogenesis; D009474:Neurons / Q000166:cytology; D010766:Phosphorylation; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009419:Nerve Tissue Proteins; D029867:Xenopus Proteins; C553500:NEUROG2 protein, Xenopus; C102938:Neurog2 protein, mouse