Recently, there has been increasing interest in the complex relationship between transcription and genome stability, with specific attention directed toward the physiological significance of molecular structures known as R-loops. These structures arise when an RNA strand invades into the DNA duplex, and their formation is involved in a wide range of regulatory functions affecting gene expression, DNA repair processes or cell homeostasis. The persistent presence of R-loops, if not effectively removed, contributes to genome instability, underscoring the significance of the factors responsible for their resolution and modification. In this review, we provide a comprehensive overview of how R-loop processing can drive either a beneficial or a harmful outcome. Additionally, we explore the potential for manipulating such structures to devise rationalized therapeutic strategies targeting the aberrant accumulation of R-loops.
Chemical and Biological Integrative Research Center, Korea Institute of Science and Technology (KIST), Seoul (02792), South Korea; Division of Bio-Medical Science & Technology, University of Science and Technology (UST), Seoul (02792), South Korea.
CRISPR/Cas systems have emerged as powerful tools for gene editing, nucleic acid detection, and therapeutic applications. Recent advances in single-molecule techniques have provided new insights into the DNA-targeting mechanisms of CRISPR/Cas systems, in particular, Types I, II, and V. Here, we review how single-molecule approaches have expanded our understanding of key processes, namely target search, recognition, and cleavage.
R-loops, RNA-DNA hybrid structures, are integral to key cellular processes such as transcriptional regulation, DNA replication, and repair. However, aberrant accumulation of R-loops can compromise genomic integrity, leading to the development of various diseases. Emerging evidence underscores the pivotal role of RNA methylation modifications, particularly N6-methyladenosine (mA) and 5-methylcytosine (mC), in orchestrating the formation, resolution, and stabilization of R-loops.
R-loops involve in various biological processes under human normal physiological conditions. Disruption of R-loops can lead to disease onset and affect the progression of illnesses, particularly in cancers. Herein, we summarized and discussed the regulative networks, phenotypes and future directions of R-loops in cancers.
R-loops can act as replication fork barriers, creating transcription-replication collisions and inducing replication stress by arresting DNA synthesis, thereby possibly causing aberrant processing and the formation of DNA strand breaks. RNase H1 (RH1) is one of the enzymes that participates in R-loop degradation by cleaving the RNA strand within a hybrid RNA-DNA duplex. In this study, the kinetic features of the interaction of RH1 from with R-loops of various structures were investigated.
The mechanism of transcription proceeds through the formation of R-loop structures containing a DNA-RNA heteroduplex and a single-stranded DNA segment that should be placed inside the elongation complex; therefore, these nucleic acid segments are limited in length. The attachment of each nucleotide to the 3' end of an RNA strand requires a repeating cycle of incoming nucleoside triphosphate binding, catalysis, and enzyme translocation. Within these steps of transcription elongation, RNA polymerase sequentially goes through several states and is post-translocated, catalytic, and pre-translocated.
