Zebrafish Ski7 tunes RNA levels during the oocyte-to-embryo transition

Abstract

Post-transcriptional mechanisms are crucial for the regulation of gene expression.These mechanisms are particularly important during rapid developmental transitions such as the oocyte-to-embryo transition, which is characterized by dramatic changes to the developmental program in the absence of nuclear transcription. Under these conditions, changes to the RNA content are solely dependent on RNA degradation.Although several mechanisms that promote RNA decay during embryogenesis have been identified, it remains unclear which cellular machineries contribute to remodeling the maternal transcriptome during the oocyte-to-embryo transition. Here, we focused on the auxiliary 3'-to-5' degradation factor Ski7 in zebrafish as its mRNA peaks during this time frame. Homozygous ski7 mutant fish were viable and developed into morphologically normal adults, yet they had decreased fertility. Consistent with the idea that Ski7 participates in remodeling the transcriptome during the oocyte-toembryo transition, transcriptome profiling identified stage-specific mRNA targets of Ski7. Genes upregulated in ski7 mutants were generally lowly expressed in wild type, suggesting that Ski7 maintains low transcript levels for this subset of genes. GO enrichment analyses of genes mis-regulated in ski7 mutants implicated Ski7 in the regulation of redox processes. This was confirmed experimentally by an increased resistance of ski7 mutant embryos to reductive stress. Overall, our results provide first insights into the physiological role of vertebrate Ski7 as an important posttranscriptional regulator during the oocyte-to-embryo transition.

RNA degradation is required for the germ-cell to maternal transition in Drosophila

“…mRNAs produced during oogenesis are subsequently cleared during the oocyte-to-embryo transition (OET) and the maternal-to-zygotic transition (MZT) to promote a zygotic identity. [69][70][71] Thus, RNA degradation bookends an oocyte's fate, regulating both its inception and termination.…”

Sperm membrane proteins DCST1 and DCST2 are required for the sperm-egg fusion process in mice and fish

“…To clone the coding sequence of the Dcst2 RING finger domain, RNA was isolated from adult testis using the standard TRIzol (Invitrogen) protocol followed by phenol/chloroform extraction. cDNA was synthesized using the iSCRIPT cDNA (testis, ovary, mature oocytes) 18 and GSE147112 (oogenesis, mature oocytes) 19 . (magenta) in zebrafish embryos.…”

“…They belong to the class of DC-STAMPlike domain-containing proteins and are multi-pass transmembrane proteins with an intracellular C-terminus containing a non-canonical RING finger domain 13,16,17 . DCSTAMP was shown to localize to the plasma membrane and endoplasmic reticulum (ER) membrane in dendritic cells and osteoclasts [16][17][18][19] . These cell types in Dcstamp KO mice show no apparent defect in differentiation into the osteoclast lineage and cytoskeletal structure, yet osteoclasts and FBGCs are unable to fuse to form terminally differentiated multinucleated cells 14 .…”

RNA degradation sculpts the maternal transcriptome duringDrosophilaoogenesis

“…We speculate that the GMT exists to enable both the transition from germ cell to oocyte identity and the accrual of the maternal RNA contribution to the embryo. After fertilization, the maternal contribution is subsequently cleared during the oocyteto-embryo and maternal-to-zygotic transitions (MZT) to promote a zygotic identity [69][70][71] . Thus, RNA degradation bookends an oocyte's fate, regulating both its initiation and termination.…”