Temporal and spatial regulation of a gene expression by the spatial arrangement of the cis-elements at proximal promoter region in vivo.

Abstract

Eucaryotic transcription is mainly controlled by the interactions among general transcription factors and transacting factors acting on the enhancers or silencers located either upstream or downstream of the promoter located at a variable distance. Particularly, transcription factors acting on the proximal promoter located immediately upstream of the transcription start site play a major role. Interestingly, the combination and the spatial arrangement of binding sites for various transcription factors are unique in every gene. We investigated the importance of the feature using the Drosophila transgene system. We prepared Drosophila gene promoter-LacZ fusion gene constructs with transcription factor binding sites introduced at a proximal promoter in 3 possible configurations. We obtained several lines of transgene with each P-element fusion transgene construct by micro-injection into Drosophila embryo w1118 and analyzed the embryonic transgene LacZ expression patterns. Regardless of differences in spatial arrangements, the transgenes showed almost identical temporal and spatial expression patterns. The major features of transgene expression such as expression boundaries, and onset of expression were identical. Our results suggest that the presence of a unique set of transcription factor binding sites at a reasonable distance is important in the spatial and temporal regulation of gene expression and the configuration of transcription binding sites is not critical.