Maternal- and Somatic-type snoRNA Expression and Processing in Zebrafish Development

Pagano, J. F. B.; Locati, M. D.; Ensik, W. A.; Olst, M. v.; van Leeuwen, S.; De Leeuw, W. C.; Nehrdich, U.; Spaink, H. P.; Rauwerda, H.; Jonker, M. J.; Dekker, R. J.; Breit, T. M.

doi:10.1101/858936

bioRxiv · 10.1101/858936

Maternal- and Somatic-type snoRNA Expression and Processing in Zebrafish Development

Pagano, J. F. B.·Locati, M. D.·Ensik, W. A.·Olst, M. v.·van Leeuwen, S.·De Leeuw, W. C.·Nehrdich, U.·Spaink, H. P.·Rauwerda, H.·Jonker, M. J.·Dekker, R. J.·Breit, T. M.

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Abstract

Small nucleolar RNAs (snoRNAs) are non-coding RNAs that play an important role in the complex maturation process of ribosomal RNAs (rRNAs). SnoRNAs are categorized in classes, with each class member having several variants present in a genome. Similar to our finding of specific rRNA expression types in zebrafish embryogenesis, we discovered preferential maternal- and somatic-expression for snoRNAs. Most snoRNAs and their variants have higher expression levels in somatic tissues than in eggs, yet we identified three snoRNAs; U3, U8 and snoZ30 of which specific variants show maternal- or somatic-type expression. For U3 and U8 we also found small-derived snoRNAs that lack their 5 rRNA recognition part and are essentially Domain II hairpin structures (U-DII). These U-DII snoRNAs from variants showed similar preferential expression, in which maternal-type variants are prominently expressed in eggs and subsequently replaced by a somatic-type variants during embryogenesis. This differential expression is related to the organization in tandem repeats (maternal type) or solitary (somatic-type) genes of the involved U snoRNA loci. The collective data showed convincingly that the preferential expression of snoRNAs is achieved by transcription regulation, as well as through RNA processing. Finally, we observed small-RNAs derived from internal transcribed spacers (ITSs) of a U3 snoRNA loci that via complementarity binding, may be involved in the biosynthesis of U3-DII snoRNAs. Altogether, the here described maternal- and somatic-type snoRNAs are the latest addition to the developing story about the dual ribosome system in zebrafish development.

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Pagano, J. F. B., Locati, M. D., Ensik, W. A., Olst, M. v., van Leeuwen, S., De Leeuw, W. C., Nehrdich, U., Spaink, H. P., Rauwerda, H., Jonker, M. J., Dekker, R. J., Breit, T. M.. 2019-11-28. Maternal- and Somatic-type snoRNA Expression and Processing in Zebrafish Development. https://doi.org/10.1101/858936

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