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MicroRNAs (miRNAs) are a class of regulatory RNAs of approximately 21 nucleotides that posttranscriptionally regulate gene expression by directing mRNA cleavage or translational inhibition. Increasing evidence points to a potential role of miRNAs in diverse physiological processes. miR398 targets two closely related Cu/Zn superoxide dismutases (cytosolic(More)
Cold temperatures trigger the expression of the CBF family of transcription factors, which in turn activate many downstream genes that confer freezing tolerance to plants. It has been shown previously that the cold regulation of CBF3 involves an upstream bHLH-type transcription factor, ICE1. ICE1 binds to the Myc recognition sequences in the CBF3 promoter.(More)
Argonautes (AGOs) are conserved proteins that contain an RNA-binding PAZ domain and an RNase H-like PIWI domain. In Arabidopsis, except for AGO1, AGO4 and AGO7, the roles of seven other AGOs in gene silencing are not known. We found that a mutation in AGO6 partially suppresses transcriptional gene silencing in the DNA demethylase mutant ros1-1. In(More)
DNA methylation is an important epigenetic mark for transcriptional gene silencing (TGS) in diverse organisms. Recent studies suggest that the methylation status of a number of genes is dynamically regulated by methylation and demethylation. In Arabidopsis, active DNA demethylation is mediated by the ROS1 (repressor of silencing 1) subfamily of(More)
Post-translational modifications of histones play crucial roles in the genetic and epigenetic regulation of gene expression from chromatin. Studies in mammals and yeast have found conserved modifications at some residues of histones as well as non-conserved modifications at some other sites. Although plants have been excellent systems to study epigenetic(More)
Activating mutations in KRAS are among the most frequent events in diverse human carcinomas and are particularly prominent in human pancreatic ductal adenocarcinoma (PDAC). An inducible Kras(G12D)-driven mouse model of PDAC has established a critical role for sustained Kras(G12D) expression in tumor maintenance, providing a model to determine the potential(More)
Epigenetic regulation involves reversible changes in DNA methylation and/or histone modification patterns. Short interfering RNAs (siRNAs) can direct DNA methylation and heterochromatic histone modifications, causing sequence-specific transcriptional gene silencing. In animals and yeast, histone H2B is known to be monoubiquitinated, and this regulates the(More)
The Arabidopsis DNA glycosylase/lyase ROS1 participates in active DNA demethylation by a base-excision pathway. ROS1 has been shown to be required for demethylating a transgene promoter. To determine the function of ROS1 in demethylating endogenous loci, we carried out bisulfite-sequencing analysis of several transposons and other genes in the ros1 mutant.(More)
Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers in western countries, with a median survival of 6 months and an extremely low percentage of long-term surviving patients. KRAS mutations are known to be a driver event of PDAC, but targeting mutant KRAS has proved challenging. Targeting oncogene-driven signalling pathways is a(More)
DNA methylation is important for stable transcriptional gene silencing. DNA methyltransferases for de novo as well as maintenance methylation have been well characterized. However, enzymes responsible for active DNA demethylation have been elusive and several reported mechanisms of active demethylation have been controversial. There has been a critical need(More)