title: MicroRNA processing machinery in the developing chick embryo.
abstract: Gene expression regulation during embryo development is under strict regulation to ensure proper gene expression in both time and space. The involvement of microRNAs (miRNA) in early vertebrate development is documented and inactivation of different proteins involved in miRNA synthesis results in severe malformations or even arrests vertebrate embryo development. However, there is very limited information on when and in what tissues the genes encoding these proteins are expressed. Herein, we report a detailed characterization of the expression patterns of DROSHA, DGCR8, XPO5 and DICER1 in the developing chick embryo, from HH1 (when the egg is laid) to HH25 (5-days incubation), using whole mount in situ hybridization and cross-section analysis. We found that these genes are co-expressed in multiple tissues, mostly after stage HH4. Before early gastrulation DICER1 expression was never detected, suggesting the operation of a Dicer-independent pathway for miRNA synthesis. Our results support an important role for miRNAs in vertebrate embryo development and provide the necessary framework to unveil additional roles for these RNA processing proteins in development.
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Gil
authors.initials: G
authors.lastname: Carraco
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Ana N
authors.initials: AN
authors.lastname: Gonçalves
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Serra
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal. Electronic address: raquel.pego.andrade@gmail.com.
authors.forename: Raquel P
authors.initials: RP
authors.lastname: Andrade
mesh_terms: D000818:Animals; D002642:Chick Embryo; D047108:Embryonic Development / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D028884:Karyopherins; D035683:MicroRNAs; D016601:RNA-Binding Proteins; D043244:Ribonuclease III
keywords: Chick embryo; DGCR8; DICER1; DROSHA; MicroRNA machinery; XPO5