Interleukin-27 (IL-27) is an immunoregulatory cytokine that suppresses inflammation through multiple mechanisms, including induction of IL-10, but the transcriptional network mediating its diverse fun Show more
Interleukin-27 (IL-27) is an immunoregulatory cytokine that suppresses inflammation through multiple mechanisms, including induction of IL-10, but the transcriptional network mediating its diverse functions remains unclear. Combining temporal RNA profiling with computational algorithms, we predict 79 transcription factors induced by IL-27 in T cells. We validate 11 known and discover 5 positive (Cebpb, Fosl2, Tbx21, Hlx, and Atf3) and 2 negative (Irf9 and Irf8) Il10 regulators, generating an experimentally refined regulatory network for Il10. We report two central regulators, Prdm1 and Maf, that cooperatively drive the expression of signature genes induced by IL-27 in type 1 regulatory T cells, mediate IL-10 expression in all T helper cells, and determine the regulatory phenotype of colonic Foxp3 Show less
The role of the actin cytoskeleton in relation to mitochondria function and dynamics is only recently beginning to be recognized. Myo19 is an actin-based motor that is bound to the outer mitochondrial Show more
The role of the actin cytoskeleton in relation to mitochondria function and dynamics is only recently beginning to be recognized. Myo19 is an actin-based motor that is bound to the outer mitochondrial membrane and promotes the localization of mitochondria to filopodia in response to glucose starvation. However, how glucose starvation induces mitochondria localization to filopodia, what are the dynamics of this process and which enzymatic adaptation allows the translocation of mitochondria to filopodia are not known. Here we show that reactive oxygen species (ROS) mimic and mediate the glucose starvation induced phenotype. In addition, time-lapse fluorescent microscopy reveals that ROS-induced Myo19 motility is a highly dynamic process which is coupled to filopodia elongation and retraction. Interestingly, Myo19 motility is inhibited by back-to-consensus-mutation of a unique residue of class XIX myosins in the motor domain. Kinetic analysis of the purified mutant Myo19 motor domain reveals that the duty ratio (time spent strongly bound to actin) is highly compromised in comparison to that of the WT motor domain, indicating that Myo19 unique motor properties are necessary to propel mitochondria to filopodia tips. In summary, our study demonstrates the contribution of actin-based motility to the mitochondrial localization to filopodia by specific cellular cues. Show less
The mechanisms whereby the crucial pluripotency transcription factor Oct4 regulates target gene expression are incompletely understood. Using an assay system based on partially differentiated embryoni Show more
The mechanisms whereby the crucial pluripotency transcription factor Oct4 regulates target gene expression are incompletely understood. Using an assay system based on partially differentiated embryonic stem cells, we show that Oct4 opposes the accumulation of local H3K9me2 and subsequent Dnmt3a-mediated DNA methylation. Upon binding DNA, Oct4 recruits the histone lysine demethylase Jmjd1c. Chromatin immunoprecipitation (ChIP) time course experiments identify a stepwise Oct4 mechanism involving Jmjd1c recruitment and H3K9me2 demethylation, transient FACT (facilitates chromatin transactions) complex recruitment, and nucleosome depletion. Genome-wide and targeted ChIP confirms binding of newly synthesized Oct4, together with Jmjd1c and FACT, to the Pou5f1 enhancer and a small number of other Oct4 targets, including the Nanog promoter. Histone demethylation is required for both FACT recruitment and H3 depletion. Jmjd1c is required to induce endogenous Oct4 expression and fully reprogram fibroblasts to pluripotency, indicating that the assay system identifies functional Oct4 cofactors. These findings indicate that Oct4 sequentially recruits activities that catalyze histone demethylation and depletion. Show less