Abstract
The RNAi machinery is a mighty regulator in a myriad of life events. Despite lines of evidence that small RNAs and components of the RNAi pathway may be associated with structure and behavior of mitotic chromosomes in diverse organisms, a direct role of the RNAi pathway in mammalian mitotic chromosome segregation remains elusive. Here we report that Dicer and AGO2, two central components of the mammalian RNAi pathway, participate in the chromosome segregation. Knockdown of Dicer or AGO2 results in a higher incidence of chromosome lagging, and this effect is independent from microRNAs as examined with DGCR8 knockout cells. Further investigation has revealed that α-satellite RNA, a noncoding RNA derived from centromeric repeat region, is managed by AGO2 under the guidance of endogenous small interference RNAs (ASAT siRNAs) generated by Dicer. Furthermore, the slicer activity of AGO2 is essential for the chromosome segregation. Level and distribution of chromosome-associated α-satellite RNA have crucial regulatory effect on the localization of centromeric proteins such as centromere protein C1 (CENPC1). With these results, we also provide a paradigm in which the RNAi pathway participates in vital cellular events through the maintenance of level and distribution of noncoding RNAs in cells.
Highlights
The centromere is a special region of chromosome needed for successful assembly of kinetochore and chromosome attachment to spindle [1,2,3,4]
Our data support a model in which the RNA interference (RNAi) machinery participates in chromosome segregation by directly keeping the level and distribution of α-satellite RNA on mitotic chromosomes in check (Figure 6)
Dicer generates endo-ASAT small interference RNA (siRNA) presumably from double-stranded RNAs derived from the centromeric repeats, as transcripts from both directions of the repeats are known to exist in mammalian cells [34]
Summary
The centromere is a special region of chromosome needed for successful assembly of kinetochore and chromosome attachment to spindle [1,2,3,4]. Studies have demonstrated that transcripts from the centromeric core associate with centromeric core proteins to serve as integral components of the centromere and kinetochore [2, 3, 7,8,9,10]. Centromeric α-satellite RNA associates directly with centromere protein C1 (CENPC1) and facilitates nucleoprotein assembly at the mitotic centromere [7, 11,12,13]. CENPC1 has both RNA-binding and DNA-binding capacity [7, 8] This protein is essential for the integrity and localization of kinetochore, and loss of CENPC1 induces chromosome lagging [14, 15]. In a chicken–human hybrid cell line, loss of Dicer results in a higher level of transcripts from α-satellite sequences [20]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
