Extensive studies in various plants show that the anthocyanin biosynthetic process is affected by environmental factors and regulated by many transcription factors through sophisticated regulatory networks. However, i...Extensive studies in various plants show that the anthocyanin biosynthetic process is affected by environmental factors and regulated by many transcription factors through sophisticated regulatory networks. However, it remains largely unclear about the roles of microRNA in this process. Here, we demonstrate that miR858a is a positive regulator of anthocyanin biosynthesis in Arabidopsis seedlings. Overexpression of miR858a enhances the accumulation of anthocyanins, whereas the reduced miR858a activity results in low levels of anthocyanins in STTM858 transgenic plants. We found that miR858a inhibits the expression of MYBL2, a key negative regulator of anthocyanin biosynthesis, by translational repression. In addition, ELONGATED HYPOCOTYL 5 （HYS） was shown to directly bind the MYBL2 promoter and represses its expression via specific histone modifications. Interestingly, we found that miR858a exhibits light- responsive expression in an HY5-dependent manner. Together, these results delineate the HY5- MIR858a-MYBL2 loop as a cellular mechanism for modulating anthocyanin biosynthesis, suggesting that integration of transcriptional and posttranscriptional regulation is critical for governing proper anthocyanin accumulation in response to light and other environmental factors.展开更多
MicroRNAs(miRNAs)are trans-acting small regulatory RNAs that work coordinately with transcription factors(TFs)to shape the repertoire of cellular m RNAs available for translation.Despite our growing knowledge of indiv...MicroRNAs(miRNAs)are trans-acting small regulatory RNAs that work coordinately with transcription factors(TFs)to shape the repertoire of cellular m RNAs available for translation.Despite our growing knowledge of individual plant miRNAs,their global roles in gene regulatory networks remain mostly unassessed.Based on interactions obtained from public databases and curated from the literature,we reconstructed an integrated miRNA network in Arabidopsis that includes 66 core TFs,318 miRNAs,and 1712 downstream genes.We found that miRNAs occupy distinct niches and enrich miRNA-containing feed-forward loops(FFLs),particularly those with miRNAs as intermediate nodes.Further analyses revealed that miRNA-containing FFLs coordinate TFs located in different hierarchical layers and that intertwined miRNA-containing FFLs are associated with party and date miRNA hubs.Using the date hub MIR858A as an example,we performed detailed molecular and genetic analyses of three interconnected miRNA-containing FFLs.These analyses revealed individual functions of the selected miRNA-containing FFLs and elucidated how the date hub miRNA fulfills multiple regulatory roles.Collectively,our findings highlight the prevalence and importance of miRNA-containing FFLs,and provide new insights into the design principles and control logics of miRNA regulatory networks governing gene expression programs in plants.展开更多
文摘Extensive studies in various plants show that the anthocyanin biosynthetic process is affected by environmental factors and regulated by many transcription factors through sophisticated regulatory networks. However, it remains largely unclear about the roles of microRNA in this process. Here, we demonstrate that miR858a is a positive regulator of anthocyanin biosynthesis in Arabidopsis seedlings. Overexpression of miR858a enhances the accumulation of anthocyanins, whereas the reduced miR858a activity results in low levels of anthocyanins in STTM858 transgenic plants. We found that miR858a inhibits the expression of MYBL2, a key negative regulator of anthocyanin biosynthesis, by translational repression. In addition, ELONGATED HYPOCOTYL 5 （HYS） was shown to directly bind the MYBL2 promoter and represses its expression via specific histone modifications. Interestingly, we found that miR858a exhibits light- responsive expression in an HY5-dependent manner. Together, these results delineate the HY5- MIR858a-MYBL2 loop as a cellular mechanism for modulating anthocyanin biosynthesis, suggesting that integration of transcriptional and posttranscriptional regulation is critical for governing proper anthocyanin accumulation in response to light and other environmental factors.
基金supported by the National Key R&D Program of China(Grant No.2017YFA0503800)the National Natural Science Foundation of China(Grant No.31621001)。
文摘MicroRNAs(miRNAs)are trans-acting small regulatory RNAs that work coordinately with transcription factors(TFs)to shape the repertoire of cellular m RNAs available for translation.Despite our growing knowledge of individual plant miRNAs,their global roles in gene regulatory networks remain mostly unassessed.Based on interactions obtained from public databases and curated from the literature,we reconstructed an integrated miRNA network in Arabidopsis that includes 66 core TFs,318 miRNAs,and 1712 downstream genes.We found that miRNAs occupy distinct niches and enrich miRNA-containing feed-forward loops(FFLs),particularly those with miRNAs as intermediate nodes.Further analyses revealed that miRNA-containing FFLs coordinate TFs located in different hierarchical layers and that intertwined miRNA-containing FFLs are associated with party and date miRNA hubs.Using the date hub MIR858A as an example,we performed detailed molecular and genetic analyses of three interconnected miRNA-containing FFLs.These analyses revealed individual functions of the selected miRNA-containing FFLs and elucidated how the date hub miRNA fulfills multiple regulatory roles.Collectively,our findings highlight the prevalence and importance of miRNA-containing FFLs,and provide new insights into the design principles and control logics of miRNA regulatory networks governing gene expression programs in plants.
