Biology subjects

Trost, H.

Publications and source records attributed to Trost, H..

3 recordsLinked to original sources

bioRxiv2024

Functions of PMS2 and MLH1 important for regulation of divergent repeat-mediated deletions

Repeat-mediated deletions (RMDs) are a type of deletion rearrangement that utilizes two repetitive elements to bridge a DNA double-strand break (DSB) that leads to loss of the intervening sequence and one of the repeats. Sequence divergence between repeats causes RMD suppression and indeed this divergence must be resolved in the RMD products. The mismatch repair factor, MLH1, was shown to be critical for both RMD suppression and a polarity of sequence divergence resolution in RMDs. Here, we sought to study the interrelationship between these two aspects of RMD regulation (i.e., RMD suppression and polar divergence resolution), by examining several mutants of MLH1 and its binding partner PMS2. To begin with, we show that PMS2 is also critical for both RMD suppression and polar resolution of sequence divergence in RMD products. Then, with six mutants of the MLH1-PMS2 heterodimer, we found several different patterns: three mutants showed defects in both functions, one mutant showed loss of RMD suppression but not polar divergence resolution, whereas another mutant showed the opposite, and finally one mutant showed loss of RMD suppression but had a complex effect on polar divergence resolution. These findings indicate that RMD suppression vs. polar resolution of sequence divergence are distinct functions of MLH1-PMS2. HIGHLIGHTSO_LIMLH1-PMS2 suppresses divergent repeat-mediated deletions (RMDs). C_LIO_LIMLH1-PMS2 promotes polar resolution of sequence divergence. C_LIO_LISeveral mutants of MLH1-PMS2 affect both aspects of RMDs. C_LIO_LISome MLH1-PMS2 mutants affect only one aspect of RMDs. C_LIO_LISuppression of RMDs vs. polar resolution of divergence appear distinct. C_LI

molecular biology↗

bioRxiv2022

Mismatch resolution for repeat-mediated deletions show a polarity that is mediated by MLH1

Repeat-mediated deletions (RMDs) are a type of chromosomal rearrangement between two homologous sequences that causes loss of the sequence between the repeats, along with one of the repeats. Sequence divergence between repeats suppresses RMDs; the mechanisms of such suppression and of resolution of the mismatched bases remains poorly understood. We identified RMD regulators using a set of reporter assays in mouse cells that test two key parameters: repeat sequence divergence and the distances between one repeat and the initiating chromosomal double-strand break. We found that the mismatch repair factor MLH1 suppresses RMDs with sequence divergence in a manner that is epistatic with the mismatch repair factors MSH2 and MSH6, and which is dependent on residues in MLH1 and its binding partner PMS2 that are important for nuclease activity. Additionally, we found that resolution of mismatches in the RMD product have a specific polarity, where mismatched bases that are proximal to the chromosomal break end are preferentially removed. Moreover, we found that the MLH1 endonuclease domain is important for this polarity of mismatch resolution. Finally, we identified distinctions between MLH1 vs. TOP3 in regulation of RMDs. We suggest that MLH1 suppresses RMDs with sequence divergence, while also promoting directional mismatch resolution.

molecular biology↗

bioRxiv2020

G4C2 repeat RNA mediates the disassembly of the nuclear pore complex in C9orf72 ALS/FTD

Nucleocytoplasmic transport, controlled by the nuclear pore complex, has recently emerged as a pathomechanism underlying neurodegenerative diseases including C9orf72 ALS/FTD. However, little is known about the underlying molecular events and the underlying biology in human neurons. Using super resolution structured illumination microscopy of twenty three nucleoporins in nuclei from C9orf72 iPSC derived neurons and postmortem human tissue we identify a unique subset of eight nucleoporins lost from human neuronal nuclei. POM121, an integral transmembrane nucleoporin, appears to coordinate the composition of the nucleoporins within human neuronal nuclei ultimately impacting nucleocytoplasmic transport, and subsequent cellular toxicity in C9orf72 iPSNs. These data suggest that POM121 is a critical nucleoporin in the maintenance of the nuclear localization of specific nucleoporins in human neurons. Moreover, loss of nuclear POM121, as a result of expanded C9orf72 ALS/FTD repeat RNA, initiates a pathological cascade affecting nucleoporin composition within neuronal nuclei, nuclear pore complex function, and overall downstream neuronal survival.

neuroscience↗