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

DAVID, A.P.; ARMAS, P.; CALCATERRA, N.B.; WEINER, A.

Praga

Congreso; G4thering - 6th International Meeting on Quadruplex Nucleic Acids.; 2017

6th International Meeting on Quadruplex Nucleic Acids.

One of the major questions ofScience is how a unique cell, the fertilized egg, develops in a complexmulticellular organism. Now we know that during embryonic development, geneexpression is orchestrated by specific and highly evolutionarily conserved mechanismsthat take place accurately, both at spatial and temporal levels. It is widelyknown that during all stages of embryonic development gene expression isregulated not only by protein-mediated transcriptional control but also bychromatin state. Therefore, we investigated the contribution of G-quadruplexes(G4) to the transcriptional control of genes required for the proper vertebrateembryonic development. We searched insilico for orthologous genes from human, mouse and zebrafish reported asrelated to developmental processes and containing at least one potential G4sequence (PQS) on their proximal promoter regions (PPRs) in the same strandrelative to transcription for the three species. The found PQSs were tested in vitro for the formation of G4 by usingtypical biochemical and biophysical approaches. In cellulo experimentssuggested a transcriptional activator role for some PQSs found in PPRs, whichwas further confirmed in vivo in developing zebrafish embryos by TMPyP4 orspecific antisense oligonucleotides (ASO) microinjection. Importantly, ASOmicroinjection recapitulated specific embryonic developmental phenotypesreported for the knock-down of the corresponding genes obtained by otherexperimental strategies (e.g., specific morpholino microinjection).Furthermore, we found that overexpression of a G4-resolving protein inzebrafish developing embryos led to the transcriptional down-regulation of agene regulated by G4 that is essential for craniofacial development. Resultspresented here provide compelling evidence that G4 have a critical role in thestrictly regulated differentiation and functional coordination of diversecellular types required for ensuring the development of a whole multicellularorganism. Moreover, our results suggest that the role of G4 during developmentcan be modulated by G4-interacting proteins.