Human pericentromeric tandemly repeated DNA is transcribed at the end of oocyte maturation and is associated with membraneless mitochondria-associated structures

M. A. Dobrynin, N. M. Korchagina, A. D. Prjibelski, D. Shafranskaya, D. I. Ostromyshenskii, K. Shunkina, I. Stepanova, A. V. Kotova, O. I. Podgornaya, N. I. Enukashvily
2020 Scientific Reports  
AbstractMost of the human genome is non-coding. However, some of the non-coding part is transcriptionally active. In humans, the tandemly repeated (TR) pericentromeric non-coding DNA—human satellites 2 and 3 (HS2, HS3)—are transcribed in somatic cells. These transcripts are also found in pre- and post-implantation embryos. The aim of this study was to analyze HS2/HS3 transcription and cellular localization of transcripts in human maturating oocytes. The maternal HS2/HS3 TR transcripts
more » ... anscripts transcribed from both strands were accumulated in the ooplasm in GV-MI oocytes as shown by DNA–RNA FISH (fluorescence in-situ hybridization). The transcripts' content was higher in GV oocytes than in somatic cumulus cells according to real-time PCR. Using bioinformatics analysis, we demonstrated the presence of polyadenylated HS2 and HS3 RNAs in datasets of GV and MII oocyte transcriptomes. The transcripts shared a high degree of homology with HS2, HS3 transcripts previously observed in cancer cells. The HS2/HS3 transcripts were revealed by a combination of FISH and immunocytochemical staining within membraneless RNP structures that contained DEAD-box helicases DDX5 and DDX4. The RNP structures were closely associated with mitochondria, and are therefore similar to membraneless bodies described previously only in oogonia. These membraneless structures may be a site for spatial sequestration of RNAs and proteins in both maturating oocytes and cancer cells.
doi:10.1038/s41598-020-76628-8 pmid:33184340 fatcat:5wzychjkuzarpo5dlzrz527te4