Identification of Etv4 enhancer regulatory mechanisms involved in motor pool identity

Abstract

The development of the spinal cord is a complex process that involves the precise regulation of gene expression in motor neurons. the Etv4 transcription factor defines the distinct motor pools, guiding subsequent dendrite arborization and axon innervation to target muscles. However, regulatory mechanisms for the motor pool-specific expression of Etv4 is not clear. In this study, potential enhancer elements for Etv4 were identified using previously known several bioinformatics data sets, Total 3 enhancer candidates were identified. GFP reporters and luciferase reporters were generated to test their activity in vivo and in vitro. Two enhancer candidates were selectively active in motor neuron and only one enhancer candidate was specifically active with LIM-HD factors in vitro. Furthermore, the study also used mutagenesis and deletion to identify potential transcription factor binding sites within these enhancers. Although, unpredictable activities were shown in vitro, only one mutation activity was selectively lost in chick spinal cord motor neuron area. Specifically, mutation in enhancer candidate is thought to be potential binding sites for transcription factors. These results could be useful in further characterizing the regulatory mechanisms controlling Etv4 expression and spinal cord development.