G-quadruplexes: non-canonical DNA structures controlling life from the beginning

ALDANA DAVID; PABLO ARMAS; NORA CALCATERRA; ANDREA WEINER

Praga

Congreso; 6th International Meeting on Quadruplex Nucleic Acids; 2017

One of the major questions of Science is how a unique cell, the fertilized egg, develops in a complex multicellular organism. Now we know that during embryonic development, gene expression is orchestrated by specific and highly evolutionarily conserved mechanisms that take place accurately, both at spatial and temporal levels. It is widely known that during all stages of embryonic development gene expression is regulated not only by protein-mediated transcriptional control but also by chromatin state. Therefore, we investigated the contribution of G-quadruplexes (G4) to the transcriptional control of genes required for the proper vertebrate embryonic development. We searched in silico for genes from human, mouse and zebrafish reported as related to developmental processes and containing at least a potential G4 sequence (PQS) on their proximal promoter regions PPRs). The found PQSs were tested for the formation of G4 in vitro using typical biochemical and biophysical approaches. For some of the genes containing PQSs in their PPRs, in cellulo experiments suggested a transcriptional activator role of the assessed G4, which was further confirmed in vivo in developing zebrafish embryos by TMPyP4 or specific antisense oligonucleotides (ASO) microinjection. Moreover, ASO microinjection recapitulated specific developmental phenotypes observed for the knock-down of the corresponding genes obtained by other experimental strategies (eg. specific morpholino). For one of the studied genes, we observed that ASO disruption of G4 or overexpression of a G4-resolving protein down-regulated the transcription of the evaluated gene, which in turn caused craniofacial phenotypes mimicking those reported for the respective knock-down. Results presented here provide compelling evidence that G4 has a critical role in the strictly regulated differentiation and functional coordination of diverse cellular types required for ensuring the development of a whole multicellular organism.