Epigenetic regulation of miR-203 controls neural crest migration

SANCHEZ-VASQUEZ, E.; STROBL MAZZULLA, P.H.

Santos

Congreso; VIII International Meeting of the Latin American Society for Developmental Biology; 2015

Neural crest cells (NCC) form a transient populationpresent only in very early stages of embryonic development in vertebrates.These cells are characterized by their multipotency and migratory ability, andit is known that defects in the migration process leads to severe congenitaldisorders known as neurocristopathies. NCC acquired their migratory propertiesby a process called epithelial-mesenchymal transition (EMT), similar to whathappens during initiation of tumor metastasis. It has been demonstrated that aberrantDNA methylation may deregulates the expression of microRNAs contributing to tumorspread. Considering the above, we aimed to determine the existence of an in vivo epigenetic-microRNAs regulatorynetwork that plays an important role during the EMT process in chick NCC. Thus,by in silico analysis, we found thatkey regulators of EMT in NCC, such as PHD12 and Snail2 genes, are bothtentative targets of the tumor-suppressive miR-203. Expression analysis by in situ hybridization and RT-qPCR revealsthat miR203 is highly expressed at a very early stages on neural tissues, suchus the neural plate and neural tube. However, its expression decreases in thedorsal neural tube when NCC start their delamination from the epithelium.Moreover, it was observed, using bisulfite sequencing, that genomic regulatoryregions of miR-203 are highly methylated in pre-migratory NCC, compared to thelow level of methylation observed in ventral neural tube and migratory NCC.Finally, the loss of function of miR-203, by electroporating a vector encodingmicroRNAs sponge, leads into premature migration of NCC. Taken together ourfindings indicated that DNA methylation inhibited miR-203 expression which leadsto an increase of their target genes PHD12 and Snail2; both directly involvedin the EMT process of NCC. These results show for the first time a key role forepigenetic-microRNA crosstalk in the regulation of the normal EMT process in NCC in vivo. The obtained results may havemajor implications to understand the mistakes that can lead to abnormal NCCdevelopment, as well as the far reaching implications in the understanding oftumor metastasis.