R-loops: from molecular principles to their roles in human disease

DNA encodes the instructions necessary for our cells to function. In order to read DNA's instructions, cells must first convert them into the RNA code, in a process called transcription. During transcription, newly made RNA can bind to the original DNA strand, forming structures called R-loops. R-loops are formed in all living organisms and are essential for many cellular processes. However, uncontrolled accumulation of R-loops can lead to severe human diseases such as cancer and neurodegeneration. Therefore, it is important to understand how R-loops are regulated. We will use state-of-the-art technology to study factors that control R-loop behavior in healthy cells. We will identify the mechanisms of their action, characterize their cellular targets and reveal their complex relationship with each other. This information will shed light on how R-loops contribute to human neurodegenerative diseases, and potentially identify new therapeutic targets.

R-loops are nucleic acid structures composed of an RNA/DNA hybrid and a single stand of DNA. R-loops are formed in all living organisms and have recently emerged as important players in multiple biological processes including transcription, DNA replication, epigenetics and DNA methylation and generation of antibody diversity. However, cells must maintain the correct balance of R-loops, and their mis-regulation leads to devastating human disorders, including cancer and neurodegeneration. The main aim of this proposal is to understand how R-loops are regulated in physiological conditions and how they contribute to human diseases.

RNase H is the main cellular activity that degrades the RNA in the RNA/DNA hybrid. Human cells contain two RNase H enzymes, RNase H1 and H2 and we will investigate the precise contribution of these proteins to R-loop regulation. To explore the complex interplay between multiple R-loop regulating factors and pathways in health and disease, we will use advanced biochemical, proteomic and genomic approaches. We will also study the role of pathological R-loops in Aicardi Goutières Syndrome (AGS), a neuro-inflammatory disorder resulting from mutations in RNase H2. Furthermore, we will examine how R-loops, formed at expanded trinucleotide repeats within frataxin gene, contribute to Friedreich's ataxia disorder on a molecular level. This research is likely to provide critical insights into the molecular mechanisms underlying R-loop biology in health and disease and may lead to future therapeutic approaches to treat R-loop-associated disorders.