High Throughput Analysis Reveals Novel Maternal Germline RNAs Critical for PGC Preservation and Proper Migration

DAWN OWENS; AMANDA BUTLER; TRISTÁN H. AGÜERO; KAREN NEWMAN; DEREK VAN BOOVEN; MARY LOU KING

DEVELOPMENT

COMPANY OF BIOLOGISTS LTD

Lugar: Cambridge; Año: 2017 vol. 144 p. 292 - 304

0950-1991

During oogenesis hundreds of RNAs areselectively localized to either the animal or vegetal cortical region.  These maternal RNAs include determinants ofboth somatic and germline fates. Although microarray analysis has contributedto identifying localized determinants, it is not comprehensive and is limitedto known transcripts.  Here, we utilizedhigh throughput RNA-sequencing analysis to comprehensively interrogate bothanimal and vegetal pole RNAs in the fully-grown Xenopus laevis oocyte. We identified 411 enriched RNAs at thevegetal pole, 198 of them annotated transcripts, and 27 RNAs enriched at theanimal pole, 15 annotated. Of these, 90 were novel RNAs over 4-fold enriched atthe vegetal pole and 6 over 10-fold at the animal pole. Unlike mRNAs, we foundthat microRNAs were not asymmetrically distributed.  Whole mount in situ hybridization revealed all 17 selected RNAs were localized,confirming our data set.   Biologicalfunction and network analysis of vegetally enriched transcripts identifiedprotein-modifying enzymes, receptors, ligands, RNA binding proteins and 10transcription factors or co-factors with 5 defining hubs linking 47 genes in anetwork. Initial functional studies of maternal vegetally-localized RNAs show,for the first time, that sox7 playsan important role in primordial germ cell (PGC) development and efnb1(ephrinB1), known to play important roles in migration/adhesion inthe nervous system, is required for proper PGC migration.  Based on our findings, we propose potentialpathways operating at the vegetal pole that highlight where futureinvestigations might be most fruitful.Manuscript identificationnumber: DEVELOP/2016/139220