Non-coding RNAs enter mitosis: functions, conservation and implications

Jun Pek,Toshie Kai

doi:10.1186/1747-1028-6-6

Abstract

Nuage (or commonly known as chromatoid body in mammals) is a conserved germline-specific organelle that has been linked to the Piwi-interacting RNA (piRNA) pathway. piRNAs are a class of gonadal-specific RNAs that are ~23-29 nucleotides in length and protect genome stability by repressing the expression of deleterious retrotransposons. More recent studies in Drosophila have implicated the piRNA pathway in other functions including canalization of embryonic development, regulation of maternal gene expression and telomere protection. We have recently shown that Vasa (known as Mouse Vasa Homolog in mouse), a nuage component, plays a mitotic role in promoting chromosome condensation and segregation by facilitating robust chromosomal localization of condensin I in the Drosophila germline. Vasa functions together with Aubergine (a PIWI family protein) and Spindle-E/mouse TDRD-9, two other nuage components that are involved in the piRNA pathway, therefore providing a link between the piRNA pathway and mitotic chromosome condensation. Here, we propose and discuss possible models for the role of Vasa and the piRNA pathway during mitosis. We also highlight relevant studies implicating mitotic roles for RNAs and/or nuage in other model systems and their implications for cancer development.

Highlights

Germline granules were first described in rat spermatids more than 100 years ago and were subsequently named “chromatoid bodies” in mammalian cells [1,2]
Recent studies in Drosophila have linked these germline granules to a novel class of small non-coding RNAs known as Piwi-interacting RNAs. piRNAs are a class of gonadal-specific RNAs that are ~23-29 nucleotides in length and produced in a Dicer-independent manner [5,6,7,8,9]
Nuage and the piRNA pathway in mitotic chromosome condensation and segregation We recently reported that in Drosophila, Vasa, a piRNA pathway component, promotes mitotic chromosome condensation and segregation by facilitating robust chromosomal localization of two condensin I components: CAPH and CAP-D2 [37]

Summary

Introduction

Germline granules were first described in rat spermatids more than 100 years ago and were subsequently named “chromatoid bodies” in mammalian cells [1,2]. Germline granules appear as electron-dense fibrous structures, are not bound by any membrane and localize to the cytoplasmic peri-nuclear region [3]. Since their discovery, germline granules have remained mysterious due to the fact that their precise function has not been identified. Recent studies have shown that the piRNA pathway functions to repress transposons and to regulate embryonic development and telomere protection. We are only beginning to understand the functional roles of the piRNA pathway in various biological processes

Discussion

Conclusions

Yokota S

38. Hirano T