Control of cell proliferation by microRNA networks in plants

R. RODRIGUEZ, M. MECCHIA, S. SPINELLI, C. SCHOMMER, J.F. PALATNIK

LISBON, PORTUGAL

Congreso; Meeting of International Research Scholars; 2008

MicroRNAs (miRNAs) are small RNAs of about 21 nt that recognize partially complementary sites in longer RNAs and guide them to cleavage or translational arrest. They are transcribed as larger precursors that contain a fold-back structure, which is processed by the RNase III–type enzymes DROSHA and DICER in animals and DICERLIKE1 in plants. In general, animal miRNAs recognize multiple target sites with low complementarity that are located in the 3UTR of target messenger RNAs (mRNAs) and inhibit the mRNA’s translation. Plant miRNAs usually exhibit superior complementarity to their targets than do their animal counterparts. In most cases, these miRNAs recognize only one target site located within the coding sequence of a mRNA and guide the mRNA to degradation, as do animal small interfering RNAs. Here, we present new insights into the role of miR396, a miRNA that regulates transcription factors of the plant-specific growth-regulating factor (GRF) family. Leaves of plants with high miR396 levels are smaller and have fewer cells than wild type despite a compensating increase in cell size activated in response to the decrease in cell number. Analyses of transgenic Arabidopsis plants expressing various levels of the miRNA or GRF transcripts indicated that the miR396 system is recruited several times during development of organs, at least in part as regulators of cell division, showing that miR396 ensures the correct timing and pattern of GRF expression. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development. Arabidopsis plants expressing various levels of the miRNA or GRF transcripts indicated that the miR396 system is recruited several times during development of organs, at least in part as regulators of cell division, showing that miR396 ensures the correct timing and pattern of GRF expression. It is interesting that miR319, another miRNA, stimulates cell division and has opposite effects to miR396. miR319 regulates TCP transcription factors, which bear similarities to the ubiquitous bHLH family. Studies on the mechanistic aspects of both miRNAs revealed that miR319 guides its targets to cleavage more efficiently than does miR396. Furthermore, the genetic interaction between miR396 and miR319 suggests that these miRNAs act at different hierarchical levels during plant development.