A novel long intergenic noncoding RNA indispensable for the formation of zygote in pig

Long noncoding RNAs (lncRNAs) are increasingly being recognized as modulators of mammalian early embryonic development. However, in pig, it is seldom investigated. In this study, lncRNAs were predicted using single-cell RNA-seq data on porcine early embryos from oocyte to early blastocyst. We further identified a novel nuclear long intergenic noncoding RNA (lincRNA), linc-321 , which was specifically and highly expressed in 1-cell embryo, and it was indispensable for the formation of zygote and early embryonic development in pig. Its knockdown by locked nucleic acid (LNA)-siRNA could result in developmental arrest at 1-cell stage with failure of pronuclear envelope fusion (PEF). Mechanistically, linc-321 facilitates the recruitment of SUZ12 to the TSS region of MYT1. And this recruitment is instrumental in establishing H3K27me3 modifications, consequently leading to the repression of MYT1 expression. Moreover, the failure of PEF and developmental arrest induced by loss of linc-321 could be rescued by addition of linc-321 with LNA-siRNA targeting site deletion and MYT1 knockdown. Thus, as functional lincRNA characterized in pig, linc-321 provides the clues for investigating the strictly regulated process of early embryonic development.