Regulation of pri-miRNA processing by the hnRNP-like protein AtGRP7 in Arabidopsis.
Bottom Line: AtGRP7 overexpression caused a significant reduction in the level of 30 miRNAs and an increase for 14 miRNAs with a minimum log2 fold change of ± 0.5.Mutation of an arginine in the RNA recognition motif abrogated in vivo binding and the effect on miRNA and pri-miRNA levels, indicating that AtGRP7 inhibits processing of these pri-miRNAs by direct binding.Thus, AtGRP7 is an hnRNP-like protein with a role in processing of pri-miRNAs in addition to its role in pre-mRNA splicing.
Affiliation: Molecular Cell Physiology, Bielefeld University.Show MeSH
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Mentions: AtGRP7-ox plants have reduced levels of miR390, the initiator of TAS3 ta-siRNA biogenesis (Figure 3A). This indicates that AtGRP7 also affects miRNAs that are loaded into AGO2 and AGO7 (16,55). We investigated whether the miR390-dependent TAS3 ta-siRNAs are likewise affected. A lower read coverage was observed for all three TAS3 loci in AtGRP7-ox plants (Supplementary Figure S5). Stem–loop RT-PCR confirmed that TAS3 5′D7(+) levels were reduced in AtGRP7-ox but not AtGRP7-R49Q-ox plants (Figure 3B, Supplementary Figure S6). Furthermore, expression of the ta-siRNA target ARF4 was elevated in AtGRP7-ox but not AtGRP7-R49Q-ox plants (Figure 3C).