Role of S. cerevisiaeYta7p in DNA replication

In S. cerevisiae initiation of replication occurs from discrete sites in the genome, known as origins and these display a characteristic temporal profile of activation during S phase of the cell cycle. The genomic context of origins has been demonstrated to be important to determine the time of firing, more specifically histone acetylation levels surrounding origins can influence their activation time. How increased acetylation is translated into earlier firing of specific origins is currently unknown. Bromodomains are known to bind acetylated histones in vivo. The bromodomain-containing Yta7p has been identified in a complex with various remodelers of chromatin and subunits of DNA polymerase ǫ. It is also a target of cell cycle and checkpoint kinases. Therefore, Yta7p makes an excellent candidate to bind acetylated histones surrounding replication origins and affect an alteration in the chromatin structure that could influence time of firing. Deletion of the histone deacetylase RPD3 results in a rapid S phase phenotype due to increased histone acetylation at “late-firing” origins. Increased acetylation at “late” origins leads to an advance in the time of firing of those specific origins. The aim of this study was to investigate the hypothesis that the bromodomain-containing protein Yta7p binds to histones with increased acetylation near to replication origins and subsequently influences origin firing. Hence, deletion of YTA7 would abolish the rapid S phase of a ∆rpd3 strain. Indeed the S phase of the ∆rpd3∆yta7 strain was reverted to WT duration. A role for Yta7p in DNA replication is also inferred by two additional lines of evidence presented in this thesis. Synthetic growth defects are evident when YTA7 and RPD3 deletion is combined with mutation of a third replication protein. In addition, ∆rpd3∆yta7 mutants are sensitive to HU, which is a phenotype shared by many strains with deletions in genes that encode proteins involved in DNA replication. Evidence to support a direct role of Yta7p in DNA replication events is provided by identification of an S phase specific binding of Yta7p to replication origins. Moreover, levels of Yta7p bound to early-firing origins are increased compared with their later-firing counterparts. Levels of Yta7p that are bound to “late-firing” origins are only increased in conditions of RPD3 deletion, where the resulting increase in histone acetylation at the “late-firing” origins is associated with advanced time of firing. Time of Yta7p binding at these “late” origins is also advanced concomitantly. This data supports the hypothesis that Yta7p provides a functional link between histone acetylation and time of origin activation. In searching for a specific replication linked function of Yta7p it was observed that recruitment of the FACT subunit Spt16p to replication origins was increased in conditions of YTA7 deletion. A second function for Yta7p in the S phase checkpoint was also demonstrated and the two roles of Yta7p, in DNA replication and S phase checkpoint, were separated depending upon their requirement for the bromodomain. The data produced in this thesis adds to our knowledge of DNA replication events and highlights the importance of histone modifications and chromatin remodeling to the replication field. This thesis describes the direct involvement of a protein, which was previously unassociated, with DNA replication and S phase checkpoint function and provides good ground work for future investigation

H3 K36 Methylation Helps Determine the Timing of Cdc45 Association with Replication Origins

Replication origins fire at different times during S-phase. Such timing is determined by the chromosomal context, which includes the activity of nearby genes, telomeric position effects and chromatin structure, such as the acetylation state of the surrounding chromatin. Activation of replication origins involves the conversion of a pre-replicative complex to a replicative complex. A pivotal step during this conversion is the binding of the replication factor Cdc45, which associates with replication origins at approximately their time of activation in a manner partially controlled by histone acetylation.Here we identify histone H3 K36 methylation (H3 K36me) by Set2 as a novel regulator of the time of Cdc45 association with replication origins. Deletion of SET2 abolishes all forms of H3 K36 methylation. This causes a delay in Cdc45 binding to origins and renders the dynamics of this interaction insensitive to the state of histone acetylation of the surrounding chromosomal region. Furthermore, a decrease in H3 K36me3 and a concomitant increase in H3 K36me1 around the time of Cdc45 binding to replication origins suggests opposing functions for these two methylation states. Indeed, we find K36me3 depleted from early firing origins when compared to late origins genomewide, supporting a delaying effect of this histone modification for the association of replication factors with origins.We propose a model in which K36me1 together with histone acetylation advance, while K36me3 and histone deacetylation delay, the time of Cdc45 association with replication origins. The involvement of the transcriptionally induced H3 K36 methylation mark in regulating the timing of Cdc45 binding to replication origins provides a novel means of how gene expression may affect origin dynamics during S-phase

Photoactivatable prodrugs of antimelanoma agent Vemurafenib

In this study, we report on novel photoactivatable caged prodrugs of vemurafenib. This kinase inhibitor was the first approved drug for the personalized treatment of BRAF-mutated melanoma and showed impressive results in clinical studies. However, the occurrence of severe side effects and drug resistance illustrates the urgent need for innovative therapeutic approaches. To conquer these limitations, we implemented photoremovable protecting groups into vemurafenib. In general, this caging concept provides spatial and temporal control over the activation of molecules triggered by ultraviolet light. Thus, higher inhibitor concentrations in tumor tissues might be reached with less systemic effects. Our study describes the first development of caged vemurafenib prodrugs useful as pharmacological tools. We investigated their photochemical characteristics and photoactivation. <i>In vitro</i> evaluation proved the intended loss-of-function and the light-dependent recovery of efficacy in kinase and cellular assays. The reported vemurafenib photo prodrugs represent a powerful biological tool for novel pharmacological approaches in cancer research

Spatial Organization and Molecular Correlation of Tumor-Infiltrating Lymphocytes Using Deep Learning on Pathology Images

Beyond sample curation and basic pathologic characterization, the digitized H&E-stained images of TCGA samples remain underutilized. To highlight this resource, we present mappings of tumorinfiltrating lymphocytes (TILs) based on H&E images from 13 TCGA tumor types. These TIL maps are derived through computational staining using a convolutional neural network trained to classify patches of images. Affinity propagation revealed local spatial structure in TIL patterns and correlation with overall survival. TIL map structural patterns were grouped using standard histopathological parameters. These patterns are enriched in particular T cell subpopulations derived from molecular measures. TIL densities and spatial structure were differentially enriched among tumor types, immune subtypes, and tumor molecular subtypes, implying that spatial infiltrate state could reflect particular tumor cell aberration states. Obtaining spatial lymphocytic patterns linked to the rich genomic characterization of TCGA samples demonstrates one use for the TCGA image archives with insights into the tumor-immune microenvironment

Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context

Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts

Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas

Although theMYConcogene has been implicated incancer, a systematic assessment of alterations ofMYC, related transcription factors, and co-regulatoryproteins, forming the proximal MYC network (PMN),across human cancers is lacking. Using computa-tional approaches, we define genomic and proteo-mic features associated with MYC and the PMNacross the 33 cancers of The Cancer Genome Atlas.Pan-cancer, 28% of all samples had at least one ofthe MYC paralogs amplified. In contrast, the MYCantagonists MGA and MNT were the most frequentlymutated or deleted members, proposing a roleas tumor suppressors.MYCalterations were mutu-ally exclusive withPIK3CA,PTEN,APC,orBRAFalterations, suggesting that MYC is a distinct onco-genic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such asimmune response and growth factor signaling; chro-matin, translation, and DNA replication/repair wereconserved pan-cancer. This analysis reveals insightsinto MYC biology and is a reference for biomarkersand therapeutics for cancers with alterations ofMYC or the PMN

Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin

Indigenous Peoples and research: self-determination in research governance

Indigenous Peoples are reimagining their relationship with research and researchers through greater self-determination and involvement in research governance. The emerging discourse around Indigenous Data Sovereignty has provoked discussions about decolonizing data practices and highlighted the importance of Indigenous Data Governance to support Indigenous decision-making and control of data. Given that much data are generated from research, Indigenous research governance and Indigenous Data Governance overlap. In this paper, we broaden the concept of Indigenous Data Sovereignty by using the CARE Principles for Indigenous Data Governance to discuss how research legislation and policy adopted by Indigenous Peoples in the US set expectations around recognizing sovereign relationships, acknowledging rights and interests in data, and enabling Indigenous Peoples' participation in research governance

Developmental Programming Mediated by Complementary Roles of Imprinted Grb10 in Mother and Pup

Developmental programming links growth in early life with health status in adulthood. Although environmental factors such as maternal diet can influence the growth and adult health status of offspring, the genetic influences on this process are poorly understood. Using the mouse as a model, we identify the imprinted gene Grb10 as a mediator of nutrient supply and demand in the postnatal period. The combined actions of Grb10 expressed in the mother, controlling supply, and Grb10 expressed in the offspring, controlling demand, jointly regulate offspring growth. Furthermore, Grb10 determines the proportions of lean and fat tissue during development, thereby influencing energy homeostasis in the adult. Most strikingly, we show that the development of normal lean/fat proportions depends on the combined effects of Grb10 expressed in the mother, which has the greater effect on offspring adiposity, and Grb10 expressed in the offspring, which influences lean mass. These distinct functions of Grb10 in mother and pup act complementarily, which is consistent with a coadaptation model of imprinting evolution, a model predicted but for which there is limited experimental evidence. In addition, our findings identify Grb10 as a key genetic component of developmental programming, and highlight the need for a better understanding of mother-offspring interactions at the genetic level in predicting adult disease risk