Ubiquitylation of MYC couples transcription elongation with double-strand break repair at active promoters.

The MYC oncoprotein globally affects the function of RNA polymerase II (RNAPII). The ability of MYC to promote transcription elongation depends on its ubiquitylation. Here, we show that MYC and PAF1c (polymerase II-associated factor 1 complex) interact directly and mutually enhance each other's association with active promoters. PAF1c is rapidly transferred from MYC onto RNAPII. This transfer is driven by the HUWE1 ubiquitin ligase and is required for MYC-dependent transcription elongation. MYC and HUWE1 promote histone H2B ubiquitylation, which alters chromatin structure both for transcription elongation and double-strand break repair. Consistently, MYC suppresses double-strand break accumulation in active genes in a strictly PAF1c-dependent manner. Depletion of PAF1c causes transcription-dependent accumulation of double-strand breaks, despite widespread repair-associated DNA synthesis. Our data show that the transfer of PAF1c from MYC onto RNAPII efficiently couples transcription elongation with double-strand break repair to maintain the genomic integrity of MYC-driven tumor cells.

RNAPII-dependent ATM signaling at collisions with replication forks.

Deregulation of RNA Polymerase II (RNAPII) by oncogenic signaling leads to collisions of RNAPII with DNA synthesis machinery (transcription-replication conflicts, TRCs). TRCs can result in DNA damage and are thought to underlie genomic instability in tumor cells. Here we provide evidence that elongating RNAPII nucleates activation of the ATM kinase at TRCs to stimulate DNA repair. We show the ATPase WRNIP1 associates with RNAPII and limits ATM activation during unperturbed cell cycle. WRNIP1 binding to elongating RNAPII requires catalytic activity of the ubiquitin ligase HUWE1. Mutation of HUWE1 induces TRCs, promotes WRNIP1 dissociation from RNAPII and binding to the replisome, stimulating ATM recruitment and activation at RNAPII. TRCs and translocation of WRNIP1 are rapidly induced in response to hydroxyurea treatment to activate ATM and facilitate subsequent DNA repair. We propose that TRCs can provide a controlled mechanism for stalling of replication forks and ATM activation, instrumental in cellular response to replicative stress.

NIPAT as Non-Invasive Prenatal Paternity Testing Using a Panel of 861 SNVs.

In 1997, it was discovered that maternal plasma contains Cell-Free Fetal DNA (cffDNA). cffDNA has been investigated as a source of DNA for non-invasive prenatal testing for fetal pathologies, as well as for non-invasive paternity testing. While the advent of Next Generation Sequencing (NGS) led to the routine use of Non-Invasive Prenatal Screening (NIPT or NIPS), few data are available regarding the reliability and reproducibility of Non-Invasive Prenatal Paternity Testing (NIPPT or NIPAT). Here, we present a non-invasive prenatal paternity test (NIPAT) analyzing 861 Single Nucleotide Variants (SNV) from cffDNA through NGS technology. The test, validated on more than 900 meiosis samples, generated log(CPI)(Combined Paternity Index) values for designated fathers ranging from +34 to +85, whereas log(CPI) values calculated for unrelated individuals were below -150. This study suggests that NIPAT can be used with high accuracy in real cases.

NF-YA Overexpression in Lung Cancer: LUAD.

The trimeric transcription factor (TF) NF-Y regulates the CCAAT box, a DNA element enriched in promoters of genes overexpressed in many types of cancer. The regulatory NF-YA is present in two major isoforms, NF-YAl ("long") and NF-YAs ("short"). There is growing indication that NF-YA levels are increased in tumors. Here, we report interrogation of RNA-Seq TCGA (The Cancer Genome Atlas)-all 576 samples-and GEO (Gene Expression Ominibus) datasets of lung adenocarcinoma (LUAD). NF-YAs is overexpressed in the three subtypes, proliferative, inflammatory, and TRU (terminal respiratory unit). CCAAT is enriched in promoters of tumor differently expressed genes (DEG) and in the proliferative/inflammatory intersection, matching with KEGG (Kyoto Encyclopedia of Genes and Genomes) terms cell-cycle and signaling. Increasing levels of NF-YAs are observed from low to high CpG island methylator phenotypes (CIMP). We identified 166 genes overexpressed in LUAD cell lines with low NF-YAs/NF-YAl ratios: applying this centroid to TCGA samples faithfully predicted tumors' isoform ratio. This signature lacks CCAAT in promoters. Finally, progression-free intervals and hazard ratios concurred with the worst prognosis of patients with either a low or high NF-YAs/NF-YAl ratio. In conclusion, global overexpression of NF-YAs is documented in LUAD and is associated with aggressive tumor behavior; however, a similar prognosis is recorded in tumors with high levels of NF-YAl and overexpressed CCAAT-less genes.

Overexpression and alternative splicing of NF-YA in breast cancer.

NF-Y is a CCAAT-binding trimeric transcription factor, whose regulome, interactome and oncogenic potential point to direct involvement in cellular transformation. Yet little is known about the levels of NF-Y subunits in tumors. We focused on breast carcinomas, and analyzed RNA-Seq datasets of TCGA and 54 BRCA cell lines at gene and isoforms level. We partitioned all tumors in the four major subclasses. NF-YA, but not histone-fold subunits NF-YB/NF-YC, is globally overexpressed, correlating with the proliferative Ki67 marker and a common set of 840 genes, with cell-cycle, metabolism GO terms. Their promoters are enriched in NF-Y, GC-rich and E2F sites. Surprisingly, there is an isoform switch, with the "short" isoform -NF-YAs- becoming predominant in tumors. E2F genes are also overexpressed in BRCA, but no switch in isoforms is observed. In Basal-like Claudinlow cell lines and tumors, expression of NF-YAl -long- isoform is high, together with 11 typical EMT markers and low levels of basal Keratins. Analysis of Progression-Free-Intervals indicates that tumors with unbalance of NF-YA isoforms ratios have worst clinical outcomes. The data suggest that NF-YA overexpression increases CCAAT-dependent, pro-growth genes in BRCA. NF-YAs is associated with a proliferative signature, but high levels of NF-YAl signal loss of epithelial features, EMT and acquisition of a more aggressive behavior in a subset of Claudinlow Basal-like tumors.