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bioRxiv · 10.1101/2022.01.06.474281

RETINOBLASTOMA RELATED (RBR) interaction with key factors of the RNA-directed DNA methylation (RdDM) pathway

Ruiz-Leon, J.·Espinal-Centeno, A.·Blilou, I.·Scheres, B.·Arteaga-Vazquez, M.·Cruz-Ramirez, A.
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Abstract

O_LITransposable elements and other repetitive elements are silenced by the RNA-directed DNA methylation pathway (RdDM). In RdDM, POLIV-derived transcripts are converted into double stranded RNA (dsRNA) by the activity of RDR2 and subsequently processed into 24 nucleotide short interfering RNAs (24 -nt siRNAs) by DCL3. 24-nt siRNAs are recruited by AGO4 and serve as guides to direct AGO4 - siRNA complexes to chromatin bound POLV-derived transcripts generated from the template/target DNA. The interaction between POLV, AGO4, DMS3, DRD1, RDM1 and DRM2 promotes DRM2-mediated de novo DNA methylation. C_LIO_LIThe Arabidopsis Retinoblastoma protein homolog is a master regulator of cell cycle, stem cell maintenance and development. In silico exploration of RBR protein partners revealed that several members of the RdDM pathway contain a motif that confers high affinity binding to RBR, including the largest subunits of POLIV and POLV (NRPD1 and NRPE1), the shared second largest subunit of POLIV and POLV (NRPD/E2), RDR1, RDR2, DCL3, DRM2 and SUVR2. We demonstrate that RBR binds to DRM2, DRD1 and SUVR2. We also report that seedlings from loss -of-function mutants in RdDM and in RBR show similar phenotypes in the root apical meristem. Furthermore, we show that RdDM and SUVR2 targets are up-regulated in the 35S::AmiGO-RBR background. C_LIO_LIOur results suggest a novel mechanism for RBR function in transcriptional gene silencing based on the interaction with key players of the RdDM pathway and opens several new hypotheses, including the convergence of RBR-DRM2 on the transcriptional control of TEs and several cell/tissue and stage -specific target genes. C_LI

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Ruiz-Leon, J., Espinal-Centeno, A., Blilou, I., Scheres, B., Arteaga-Vazquez, M., Cruz-Ramirez, A.. 2022-01-06. RETINOBLASTOMA RELATED (RBR) interaction with key factors of the RNA-directed DNA methylation (RdDM) pathway. https://doi.org/10.1101/2022.01.06.474281

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