Biology subjects

Yeo, N. C.

Publications and source records attributed to Yeo, N. C..

3 recordsLinked to original sources

bioRxiv2026

DHX30 is a replication stress-responsive R-loop helicase that safeguards genome stability

R-loops are three-stranded nucleic acid structures formed primarily during transcription that can obstruct replication fork progression, leading to replication stress and genome instability. Although RNA helicases are increasingly implicated in R-loop metabolism, how individual helicases safeguard genome integrity remains incompletely understood. Here we identify DHX30, a neurodevelopmental disorder-associated DExH-box RNA helicase, as a replication stress-responsive regulator of R-loops. We show that DHX30 localizes to the nucleus in addition to its known cytoplasmic and mitochondrial pools, and that its nuclear abundance in-creases following aphidicolin or camptothecin treatment. DHX30 deficiency results in RNA:DNA hybrid accumulation in human cells and zebrafish, R-loop-dependent DNA double-strand breaks, micronucleus formation, reduced DNA synthesis, and altered expression of immediate-early stress genes under basal conditions and following replication perturbation. Biochemically, DHX30 binds branched nucleic acid structures and directly unwinds R-loop substrates containing a 3' single-stranded RNA overhang in an ATP- and polarity-dependent manner. Proteomic analyses place DHX30 within a nuclear network of RNA- and R-loop-associated factors, including the RNA helicase DHX9. These findings establish DHX30 as a conserved R-loop-resolving helicase that protects from R-loop-induced replication perturbations, contributes to transcriptional homeostasis, and maintains genome stability, thereby providing a mechanistic framework for understanding DHX30-associated neurodevelopmental disorders.

molecular biology↗

bioRxiv2024

Disrupted development of sensory systems and the cerebellum in a zebrafish ebf3a mutant

Mutations in the transcription factor EBF3 results in a neurodevelopmental disorder, and studies in animal models indicate that it has a critical role in neuronal differentiation. The molecular pathways and neuron types disrupted by its loss, however, have not been thoroughly investigated. Nor have the outcomes of these changes on behavior and brain activity. Here, we generated and characterized a zebrafish ebf3a loss-of-function mutant. We discovered morphological and neural phenotypes, including an overall smaller brain size, particularly in the hypothalamus, cerebellum, and hindbrain. Brain function was also compromised, with activity strongly increased in the cerebellum and abnormal behavior at baseline and in response to visual and acoustic stimuli. From RNA-sequencing of developing larvae, notable changes included significant downregulation of genes that mark olfactory sensory neurons, the lateral line, and cerebellar Purkinje neurons. This study sets the stage for determining which downstream pathways underlie the emergence of the observed phenotypes and establishes multiple strong phenotypes that could form the basis of a drug screen.

neuroscience↗

bioRxiv2018

Enhanced bacterial immunity and mammalian genome editing via RNA polymerase-mediated dislodging of Cas9 from double strand DNA breaks.

The ability to target the Cas9 nuclease to DNA sequences via Watson-Crick base pairing with a single guide RNA (sgRNA) has provided a dynamic tool for genome editing and an essential component of adaptive immune systems in bacteria. After generating a double strand break (DSB), Cas9 remains stably bound to it. Here we show persistent Cas9 binding blocks access to DSB by repair enzymes, reducing genome editing efficiency. Cas9 can be dislodged by translocating RNA polymerases, but only if the polymerase approaches one direction towards the Cas9-DSB complex. By exploiting these RNA polymerase-Cas9 interactions, Cas9 can be conditionally converted into a multi-turnover nuclease, mediating increased mutagenesis frequencies in mammalian cells and enhancing bacterial immunity to bacteriophages. These consequences of a stable Cas9-DSB complex provide insights into the evolution of PAM sequences and a simple method of improving selection of highly active sgRNA for genome editing.

molecular biology↗