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Back-spliced RNA from Retrotransposon Binds to Centromere and Regulates Centromeric Chromatin Loops in Maize

ABSTRACT: In most plants, centromeric DNA contains highly repetitive sequences, including tandem repeats and retrotransposons; however, the roles of these sequences in the structure and function of the centromere are unclear. Here, we found that retrotransposon-derived back-spliced RNA can bind to the centromere through R-loops and regulate the formation of centromeric chromatin loops. Multiple RNA sequences from centromeric retrotransposons (CRMs) were enriched in maize (Zea mays) centromeres and back spliced RNA from CRM1 were detected. We identified three types of circular CRM1 RNAs with the same back-splicing site based on the back-spliced sequences. These circular RNAs bound to the centromere through R-loops. Two R-loop sites inside a single circular RNA promoted the formation of chromatin loops in CRM1 regions. When RNAi was used to target the back-spliced site of the circular CRM1 RNAs, the levels of R-loops and chromatin loops formed by these circular RNAs decreased, while the levels of R-loops produced by linear RNAs with similar binding sites increased. Linear RNAs with only one R-loop site could not promote chromatin loop formation. Higher levels of R-loops and lower levels of chromatin loops in the CRM1 regions of RNAi plants led to a reduced localization of the centromeric H3 variant (CENH3). Our work reveals that centromeric chromatin organization by circular CRM1 RNAs via R-loops and chromatin loops. R-loops are integral components of centromeric chromatin. Proper centromere structure is essential for CENH3 localization. CRM1 elements may have helped to build a suitable chromatin environment during centromere evolution.

ORGANISM(S): Zea mays Triticum urartu

PROVIDER: GSE137701 | GEO | 2020/01/01

REPOSITORIES: GEO

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