Konrad, Kalin D.Song, Jia L.2023-01-062023-01-062022-11-23Konrad, K. D., & Song, J. L. (2022). microRNA-124 regulates Notch and NeuroD1 to mediate transition states of neuronal development. Developmental Neurobiology, 00, 1– 25. https://doi.org/10.1002/dneu.229021932-846Xhttps://udspace.udel.edu/handle/19716/31996This is the peer reviewed version of the following article: Konrad, K. D., & Song, J. L. (2022). microRNA-124 regulates Notch and NeuroD1 to mediate transition states of neuronal development. Developmental Neurobiology, 00, 1– 25. https://doi.org/10.1002/dneu.22902, which has been published in final form at https://doi.org/10.1002/dneu.22902. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited. This article will be embargoed until 11/23/2023.MicroRNAs regulate gene expression by destabilizing target mRNA and/or inhibiting translation in animal cells. The ability to mechanistically dissect miR-124′s function during specification, differentiation, and maturation of neurons during development within a single system has not been accomplished. Using the sea urchin embryo, we take advantage of the manipulability of the embryo and its well-documented gene regulatory networks (GRNs). We incorporated NeuroD1 as part of the sea urchin neuronal GRN and determined that miR-124 inhibition resulted in aberrant gut contractions, swimming velocity, and neuronal development. Inhibition of miR-124 resulted in an increased number of cells expressing transcription factors (TFs) associated with progenitor neurons and a concurrent decrease of mature and functional neurons. Results revealed that in the early blastula/gastrula stages, miR-124 regulates undefined factors during neuronal specification and differentiation. In the late gastrula/larval stages, miR-124 regulates Notch and NeuroD1 during the transition between neuronal differentiation and maturation. Overall, we have improved the neuronal GRN and identified miR-124 to play a prolific role in regulating various transitions of neuronal development.en-USsea urchinpost-transcriptional regulationgene regulatory networkneurogenesissignaling pathwaysArticle