Biology subjects

Candelli, T.

Publications and source records attributed to Candelli, T..

3 recordsLinked to original sources

bioRxiv2018

Pervasive Transcription Fine-tunes Replication Origin Activity

RNA polymerase (RNAPII) transcription occurs pervasively, which raises the important question of its functional impact on other DNA-associated processes, including replication. In budding yeast, replication originates from Autonomously Replicating Sequences (ARSs), generally located in intergenic regions. The influence of transcription on ARSs function has been studied for decades, but these earlier studies have necessarily neglected the role of non-annotated transcription. We studied the relationships between pervasive transcription and replication origin activity using high-resolution transcription maps. We show that ARSs alter the pervasive transcription landscape by pausing and terminating neighboring RNAPII transcription, thus limiting the occurrence of pervasive transcription within origins. We provide evidence that quasi-symmetrical binding of the ORC complex to ARS borders is responsible for pausing/termination. We also show that low, physiological levels of pervasive transcription impact the function of replication origins. Overall, our results have important implications for understanding the impact of genomic location on origin function.

genetics↗

bioRxiv2018

General Regulatory Factors control the fidelity of transcription by restricting non-coding and ectopic initiation

The fidelity of transcription initiation is essential for accurate gene expression, but the determinants of start site selection are not fully understood. Rap1 and other General Regulatory Factors (GRFs) control the expression of many genes in yeast. We show that depletion of these factors induces widespread ectopic transcription initiation within promoters. This generates many novel non-coding RNAs and transcript isoforms with diverse stability, profoundly altering the coding potential of the transcriptome. Ectopic transcription initiation strongly correlates with altered nucleosome positioning. We show that Rap1 sterically constrains nucleosomes as its mere binding to the DNA can be sufficient for restoration normal nucleosome positioning, transcription initiation and gene expression. These results demonstrate an essential role for GRFs in the fidelity of transcription initiation and in the suppression of pervasive transcription, redefining current models of their function. They have general implications for the mechanism of transcription initiation and the control of gene expression.\n\nHIGHLIGHTSO_LIRap1, Abf1 and Reb1 control the fidelity of transcription initiation and suppress pervasive transcription\nC_LIO_LIWidespread ectopic transcription initiation in Rap1-deficient cells induces variegated alterations in gene expression\nC_LIO_LIAltered nucleosome positioning in GRFs-defective cells correlate with ectopic transcription initiation.\nC_LIO_LIRap1 controls nucleosomes positioning and transcription initiation at least partially by a steric hindrance mechanism\nC_LI

genomics↗

bioRxiv2018

Sharq, a versatile preprocessing and QC pipeline for Single Cell RNA-seq

Despite the meteoric rise of single cell RNA-seq, only a few preprocessing pipelines exist that are able to perform all steps from the original fastq files to a gene expression table ready for further analysis. Here we present Sharq, a versatile preprocessing pipeline designed to work with plate-based 3-end protocols that include Unique Molecular Identifiers (UMIs). Sharq performs stringent step-wise trimming of reads, assigns them to features according to a flexible hierarchical model, and uses the barcode and UMI information to avoid amplification biases and produce gene expression tables. Additionally, Sharq provides an extensive plate diagnostics report for quality control and troubleshooting, including that of spatial artefacts. The diagnostics report includes measures of the quality of the individual plate wells as well as a robust assessment which of them contain material from live cells. Collectively, the innovative approaches presented here provide a valuable tool for processing and quality control of single cell RNA-seq data.

bioinformatics↗