Transient inactivation of Notch signaling synchronizes differentiation of neural progenitor cells

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2007.01.001 Byline: Branden R. Nelson (a), Byron H. Hartman (a), Sean A. Georgi (b), Michael S. Lan (c), Thomas A. Reh (a)(b) Keywords: Notch activity; Hes1; Hes5; Proneural bHLH transcription factor; Progenitor cell; Neural differentiation; Insulinoma-associated 1 Abstract: In the developing nervous system, the balance between proliferation and differentiation is critical to generate the appropriate numbers and types of neurons and glia. Notch signaling maintains the progenitor pool throughout this process. While many components of the Notch pathway have been identified, the downstream molecular events leading to neural differentiation are not well understood. We have taken advantage of a small molecule inhibitor, DAPT, to block Notch activity in retinal progenitor cells, and analyzed the resulting molecular and cellular changes over time. DAPT treatment causes a massive, coordinated differentiation of progenitors that produces cell types appropriate for their developmental stage. Transient exposure of retina to DAPT for specific time periods allowed us to define the period of Notch inactivation that is required for a permanent commitment to differentiate. Inactivation of Notch signaling revealed a cascade of proneural bHLH transcription factor gene expression that correlates with stages in progenitor cell differentiation. Microarray/QPCR analysis confirms the changes in Notch signaling components, and reveals new molecular targets for investigating neuronal differentiation. Thus, transient inactivation of Notch signaling synchronizes progenitor cell differentiation, and allows for a systematic analysis of key steps in this process. Author Affiliation: (a) Department of Biological Structure, Box 357420, University of Washington, Seattle, WA 98195, USA (b) Neurobiology and Behavior Program, University of Washington, Seattle, WA 98195, USA (c) The Research Institute for Children, Children's Hospital, New Orleans, LA 70118, USA Article History: Received 11 July 2006; Revised 23 December 2006; Accepted 2 January 2007