Biology subjects

Sidhu, A.

Publications and source records attributed to Sidhu, A..

3 recordsLinked to original sources

bioRxiv2026

Somatic CRISPR editing of Msh3 mitigates Huntington's disease pathology in mice

Huntingtons disease (HD) is a fatal, dominantly inherited neurodegenerative disorder caused by a CAG repeat expansion in Huntingtin (HTT) exon 1. Further progressive CAG repeat expansion occurs in somatic cells, particularly in neurons, and drives the timing of clinical onset. Therefore, therapeutic strategies to slow somatic expansion are predicted to be disease-modifying. Somatic CAG expansion is driven by mismatch repair protein MSH3, a leading therapeutic target supported by human genetic data. To gain insight into the impact of targeting MSH3 at different stages of the disease process we used somatic CRISPR-Cas9 editing to knock out Msh3 in HttQ111 mice at ages of 6, 16, 24 weeks exhibiting progressively increasing somatic expansion. Intervention at all three ages slowed striatal CAG expansion, reduced nuclear huntingtin pathology and suppressed transcriptional dysregulation, with earlier intervention having greater impact. Msh3 knockout also suppressed the production of the exon 1 Htt1a transcript. The results of our study provide important preclinical information relevant to an MSH3 therapeutic in humans that would be expected to impact a subset of cells in the brain, provide insight into the influence of timing of intervention on therapeutic effectiveness and deepen our understanding of how targeting MSH3 could alter the trajectory of HD.

genetics↗

bioRxiv2024

Testing a Method for Quantifying Microplastic Content in Mytilus californianus

With the proliferation of microplastics within the environment, there has been an increased need to quantify them within organic tissues of aquatic species. Several studies have examined the potential role of mussels in filtering these contaminants, prompting interest in characterizing uptake and retention of microplastics in these species. There are a variety of methods to isolate and quantify microplastics, including density separation, enzymatic digestion, and filtration. The applicability of a combined digestion and ultrasonic bath methodology in isolating microplastics from the California mussel (Mytilus californianus Conrad, 1837) was investigated. Microplastics were added to 20-gallon tanks at 0 g (control) 8 mg. Mussel tissues from each tank were digested using potassium hydroxide solutions. These digestions were subjected to vacuum filtration and a sonication bath, then treated with a mixture of sodium hypochlorite and nitric acid. It was found that this method successfully removed organic tissue from the mussels while leaving dyed microplastics intact. The latter were quantified using fluorescent microscopy. This proof-of-principle experiment indicates that this technique can be applied to further studies on environmental impact and retention of microplastics in mussels and may also have utility for other shellfish.

zoology↗

bioRxiv2021

Role of BRCA2 DNA-binding and C-terminal domain on its mobility and conformation in DNA repair

BRCA2 is an essential protein in genome maintenance, homologous recombination and replication fork protection. Its function includes multiple interaction partners and requires timely localization to relevant sites in the nucleus. We investigated the importance of the highly conserved DNA binding domain (DBD) and C-terminal domain (CTD) of BRCA2. We generated BRCA2 variants missing one or both domains in mouse ES cells and defined their contribution in HR function and dynamic localization in the nucleus, by single particle tracking of BRCA2 mobility. Changes in molecular architecture of BRCA2 induced by binding partners of purified BRCA2 was determined by scanning force microscopy. BRCA2 mobility and DNA damage-induced increase in the immobile fraction was largely unaffected by C- terminal deletions. The purified proteins missing CTD and/or DBD were defective in architectural changes correlating with reduced homologous recombination function in cells. These results emphasize BRCA2 activity at sites of damage beyond promoting RAD51 delivery.

molecular biology↗