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Sabyasachi Das

Publications and source records attributed to Sabyasachi Das.

2 recordsLinked to original sources
PubMed2026

Structural and functional gastrointestinal abnormalities in ACTA2 R179H mice modeling multisystemic smooth muscle dysfunction syndrome.

Multisystemic smooth muscle dysfunction syndrome (MSMDS) is a rare disorder caused by ACTA2 mutations, including the R179H variant, which alters actin filament stability and dynamics and smooth muscle contractility. Cardiovascular complications dominate its clinical presentation, but gastrointestinal (GI) dysfunction significantly affects quality of life. To investigate the structural, functional, and cellular basis of gut dysmotility in MSMDS, we reviewed clinical data from 24 patients with MSMDS and studied the ACTA2 R179H mouse model. Patients exhibited severe gut dysmotility, with 75% requiring medication for chronic constipation. ACTA2 mutant mice displayed cecal and colonic dilatation, reduced intestinal length, and disrupted colonic migrating motor complexes. Delayed whole-gut transit and impaired contractile responses to electrical and pharmacological stimulation were observed. Transcriptomic analysis revealed significant actin cytoskeleton-related gene changes in smooth muscle cells, and immune profiling identified increased lymphocytic infiltration. Despite functional abnormalities, there were no obvious changes in the enteric nervous system. These findings establish ACTA2 mice as a robust model for studying GI pathology in MSMDS, elucidating the role of smooth muscle dysfunction in gut dysmotility. This model provides a foundation for developing targeted therapies aimed at restoring intestinal motility by directly addressing actin cytoskeletal disruptions in smooth muscle cells.

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PubMed2025

Treatment of a severe vascular disease using a bespoke CRISPR-Cas9 base editor in mice.

Pathogenic missense mutations in the alpha actin isotype 2 (ACTA2) gene cause multisystemic smooth muscle dysfunction syndrome (MSMDS), a genetic vasculopathy that is associated with stroke, aortic dissection and death in childhood. Here we perform mutation-specific protein engineering to develop a bespoke CRISPR-Cas9 enzyme with enhanced on-target activity against the most common MSMDS-causative mutation ACTA2 R179H. To directly correct the R179H mutation, we screened dozens of configurations of base editors to develop a highly precise corrective A-to-G edit with minimal deleterious bystander editing that is otherwise prevalent when using wild-type SpCas9 base editors. We create a murine model of MSMDS that shows phenotypes consistent with human patients, including vasculopathy and premature death, to explore the in vivo therapeutic potential of this strategy. Delivery of the customized base editor via an engineered smooth muscle-tropic adeno-associated virus (AAV-PR) vector substantially prolongs survival and rescues systemic phenotypes across the lifespan of MSMDS mice, including in the vasculature, aorta and brain. Our results highlight how bespoke mutant-specific CRISPR-Cas9 enzymes can improve mutation correction with base editors.

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