Project description:Project Abstract : Paf1C is a general transcription regulator and is associated with various human diseases. One of its subunits, CTR9, is known as a structurally and functionally core component of Paf1C. While its role in higher eukaryotes have been researched, the association between the core component and human fungal pathogen is not fully understood yet. During pre-infection process, Candida albicans adheres to the surface of hosts and sufficiently grows as the circular form. Under immune deficiency condition, C. albicans enters into the infection process and forms hyphae. Here, we performed virulence tests and transcriptome analysis to identify the role of CTR9 in two infection stages. In pre-infection process, CTR9 regulates basic cellular processes and metabolism, affecting cell growth. Of metabolic processes, methionine biosynthetic genes are significantly dependent on CTR9. This pathway hardly affects cell abundance for pre-infection stage, but has considerable effect on hyphal formation during infection stage. Therefore, it shows that methionine biosynthetic pathway mediated by CTR9 is essential for pathogenesis of C. albicans.
Project description:The human RNA polymerase II-associated factor complex (hPAFc) and its individual subunits have been implicated in human diseases including cancer. However, its involvement in breast cancer cells awaits investigation. Using data mining and human breast cancer tissue microarrays, we found that Ctr9, the key scaffold subunit in hPAFc, is highly expressed in ERα+ luminal breast cancer and the high expression of Ctr9 correlates with poor prognosis. Knockdown of Ctr9 in ERα+ breast cancer cells almost completely erased estrogen regulated transcriptional response. At the molecular level, Ctr9 enhances ERα protein stability, promotes recruitment of ERα and RNAPII and stimulates transcription elongation and transcription-coupled histone modifications. Knockdown of Ctr9, but not other hPAFc subunits, alters the morphology, proliferative capacity and tamoxifen-sensitivity of ERα+ breast cancer cells. Together, our study reveals that Ctr9, a key subunit of hPAFc, is a central regulator of estrogen signaling that drives ERα+ breast tumorigenesis, rendering it a potential target for the treatment of ERα+ breast cancer.
Project description:To study the function of Paf1C in mouse ESCs, we generated an ES cell line stably expressing a location and affinity purification (LAP)-tagged Ctr9 fusiuon protein using the bacterial astificial chromosome (BAC)-based TransgeneOmics approach. To investigate whether pluripotency and lineage control genes differentially regulated upon Paf1C depletion are direct targets of the Paf1C, we analyzed the binding of the Ctr9-LAP fusion protein by ChIP-chip and identified 2175 promoter regions that were bound by Ctr9. The supplementary bed file contains promoter regions bound by Ctr9. Keywords: ChIP-chip
Project description:To monitor global transcript changes after Paf1C depletion we transfected ESCs with esiRNA targeting Ctr9 and control esiRNA (Luc). Experiment Overall Design: 4 replicates of esiRNA tranfection controls (luciferase esiRNA) and 4 replicates of Ctr9 esiRNA tranfection samples
Project description:tRNA modifications play important roles in maintaining translation accuracy in all domains of life. Disruptions in the tRNA modification machinery, especially of the anticodon stem loop, can be lethal for many bacteria and lead to a broad range of phenotypes in baker’s yeast. Very little is known about the function of tRNA modifications in host-pathogen interactions, where rapidly changing environments and stresses require fast adaptations. We found that two closely related fungal pathogens of humans, the highly pathogenic Candida albicans and its much less pathogenic sister species, Candida dubliniensis, differ in the function of a tRNA-modifying enzyme. This enzyme, Hma1, exhibits speciesspecific effects on the ability of the two fungi to grow in the hypha morphology, which is central to their virulence potential. We show that Hma1 has tRNA-threonylcarbamoyladenosine dehydratase activity, and its deletion alters ribosome occupancy, especially at 37°C—the body temperature of the human host. A C. albicans HMA1 deletion mutant also shows defects in adhesion to and invasion into human epithelial cells and shows reduced virulence in a fungal infection model. This links tRNA modifications to host-induced filamentation and virulence of one of the most important fungal pathogens of humans.
Project description:Ctr9, the key scaffold subunit of the human RNA polymerase II (RNAPII) associated factor complex (PAFc), has been demonstrated as a positive regulator of ERα-positive breast cancer progression and ERα-target gene expression. Previously, we found that knockdown of Ctr9 reduces ERα protein stability and decreases the occupancy of ERα and RNAPII at select ERα-target genes. However, the genome-wide regulation of the occupancy of ERα and RNAPII mediated by Ctr9 is still unclear. Here, we determined the genome-wide ERα and RNAPII occupancy in response to estrogen induction and/or Ctr9 knockdown by performing chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq). We found that loss of Ctr9 dramatically decreases the global occupancy of ERα and RNAPII, highlighting the significance of Ctr9 in regulating estrogen signaling in ERα-positive breast cancer cells. Combining this resource with previously published genomic data sets, we identified a unique subset of ERα and Ctr9 target genes, and further delineates the possible independent function of Ctr9 from other subunits in PAFc.
Project description:CTR9 is the scaffold subunit in PAFc (Polymerase associated factor complex), a multifunctional complex employed in multiple steps of RNA Pol II-mediated transcription. CTR9/PAFc is well known as an evolutionarily conserved elongation factor regulating gene activation via coupling with histone modifications enzymes. However, little is known about its function to restrain repressive histone markers. Using inducible and stable CTR9 knockdown breast cancer cell lines, we discovered that the amount of H3K27me3 is strictly controlled by CTR9. Quantitative profiling on histone modifications revealed a striking increase of H3K27me3 level upon loss of CTR9. Moreover, loss of CTR9 leads to genome-wide expansion of H3K27me3, as well as increased recruitment of PRC2 on chromatin, which can be reversed by CTR9 restoration. Moreover, CTR9 depletion triggers a PRC2 subtype switch from less active PRC2.2 to PRC2.1 with higher methyltransferase activity. As a consequence, CTR9 depletion generates vulnerability that renders breast cancer cells hypersensitive to PRC2 inhibitors. Our findings that CTR9 demarcates PRC2-mediated H3K27me3 levels and genomic distribution provide a unique mechanism of transition from transcriptionally active to repressive chromatin states and shed light on the biological functions of CTR9 in development and cancer.
Project description:To monitor global transcript changes after Paf1C depletion we transfected ESCs with esiRNA targeting Ctr9 and control esiRNA (Luc).
Project description:Candida albicans is exposed to a different host environment during different site of infection. Thus, different virulence factors may be active during differenttypes of infection. However,little is known about the C. albicans genes that are required for the initiation and maintenance of candidiasis. To identify potential virulence factors relevant to hematogenously disseminated candidiasis, we determined the transcriptional response of C. albicans to human umbilical vein endothelial cells (HUVECs) in vitro. Keywords: cell interaction
Project description:Candida albicans is exposed to a different host environment during oropharyngeal candidiasis (OPC) compared to hematogenously disseminated candidiasis. Thus, different virulence factors may be active during these two types of infection. However,little is known about the C. albicans genes that are required for the initiation and maintenance of OPC. To identify potential virulence factors relevant to this disease, we determined the transcriptional response of C. albicans to oral epithelial cells in vitro. Keywords: cell interaction