A role for Flipons and miRNAs in Promoter Specification during Development?

Abstract

The classical view of gene regulation is based on prokaryotic models and the operon concept with protein-based transcription factors controlling the expression of metabolic pathways essential for bacterial adaptations in response to environmental changes. A new view for establishing cell identity is emerging in eukaryotes where RNA-based pathways provide the framework for the readout of genomic information. Another perspective poses that alternative DNA structures encoded by flipons enable switching of cellular responses from one state to another. Here we provide evidence that these RNA and DNA mechanisms are deeply connected. We present data supporting a model where flipons open up binding sites for microRNAs (miRNAs), leading to the establishment of bivalent promoters early in development whose location structures lineage-specific events. These outcomes are potentially influenced by ovarian and spermatozoan miRNAs, transmissions with evident evolutionary ramifications. The data supports a new perspective on genetic regulation, one in which the genome provides a canvas framed by flipons, sketched with miRNAs and embellished by proteins.