Biology subjects

Raguram, A.

Publications and source records attributed to Raguram, A..

3 recordsLinked to original sources

bioRxiv2026

Engineered mRNA-packaging virus-like particles enable efficient and precise mitochondrial base editing in vitro and in vivo

Mitochondrial DNA (mtDNA) base editors (mtBEs) are promising tools for studying and correcting pathogenic mtDNA mutations. However, the application of mtBEs is often hindered by substantial mtDNA-wide off-target editing that accumulates with prolonged mtBE expression resulting from plasmid DNA or viral delivery. To overcome this limitation, we developed mtBE-VLPs, a virus-like-particle (VLP) platform for transiently delivering mtBEs in vitro and in vivo with minimal off-target effects. While canonical protein-packaging VLPs yielded undetectable mtDNA base editing, engineered mRNA-packaging VLPs enabled efficient but transient mtBE cargo delivery. By iteratively engineering mRNA-packaging VLP compositions, we improved mtBE-VLP-mediated base editing efficiencies from less than 1% to greater than 50% across multiple target mtDNA loci in bulk populations of treated cultured cells. To further improve the packaging and delivery of certain mtBEs, we developed a strategy to selectively reduce mtBE cargo expression in VLP producer cells but not transduced cells, which increased VLP-mediated base editing efficiencies for certain mtBEs by 7.1-fold. Compared to plasmid DNA delivery in vitro, mtBE-VLPs exhibited equivalent on-target editing but 23- to 41-fold lower mtDNA-wide off-target editing, highlighting the improved editing specificity offered by transient mtBE delivery. mtBE-VLPs efficiently installed a pathogenic mtDNA mutation in mouse embryonic fibroblasts (88% efficiency) and corrected a pathogenic mtDNA mutation in a human patient-derived cell line (41% efficiency). Additionally, a single subretinal injection of mtBE-VLPs yielded 6-20% (average 12%) mtDNA base editing in the mouse retinal pigment epithelium with minimal mtDNA-wide off-target editing. These findings establish mRNA-packaging mtBE-VLPs as promising vehicles for efficient and precise mitochondrial base editing via transient mtBE delivery.

bioengineering↗

bioRxiv2025

Genome-wide screening reveals producer-cell modifications that improve virus-like particle production and delivery potency

Engineered virus-like particles (eVLPs) are promising vehicles for transient delivery of gene editing agents. While extensive particle engineering has yielded efficient eVLPs, it remains underexplored whether engineering the cells used to produce eVLPs could further improve eVLP properties. We developed a genome-wide screening approach to systematically investigate how genetic perturbations in producer cells influence eVLP production. This approach generates eVLPs loaded with guide RNAs that identify the genetic perturbation in the cell that produced a particular particle; the abundance of each guide RNA in eVLPs therefore reflects how the corresponding genetic perturbation influences eVLP production or cargo loading. We applied this approach to identify several genes that regulate eVLP cargo expression and loading into particles during the production process. Leveraging these insights, we engineered producer cells that support increased eVLP cargo packaging and a 2- to 9-fold increase in eVLP delivery potency across several cargo, particle, and target-cell types in cultured cells and in mice. Our findings suggest the potential of producer-cell engineering as a useful strategy for improving the utility of eVLPs and related delivery methods.

synthetic biology↗

bioRxiv2021

Programmable large DNA deletion, replacement, integration, and inversion with twin prime editing and site-specific recombinases

The targeted deletion, replacement, integration, or inversion of DNA sequences at specified locations in the genome could be used to study or treat many human genetic diseases. Here, we describe twin prime editing (twinPE), a method for the programmable replacement or excision of DNA sequence at endogenous human genomic sites without requiring double-strand DNA breaks. TwinPE uses a prime editor (PE) protein and two prime editing guide RNAs (pegRNAs) that template the synthesis of complementary DNA flaps on opposing strands of genomic DNA, resulting in the replacement of endogenous DNA sequence between the PE-induced nick sites with pegRNA-encoded sequences. We show that twinPE in human cells can perform precise deletions of at least 780 bp and precise replacements of genomic DNA sequence with new sequences of at least 108 bp. By combining single or multiplexed twinPE with site-specific serine recombinases either in separate steps or in a single step, we demonstrate targeted integration of gene-sized DNA plasmids (>5,000 bp) into safe-harbor loci including AAVS1, CCR5, and ALB in human cells. To our knowledge, these results represent the first RNA-programmable insertion of gene-sized DNA sequences into targeted genomic sites of unmodified human cells without requiring double-strand breaks or homology-directed repair. Twin PE combined with recombinases also mediated a 40,167-bp inversion at IDS that corrects a common Hunter syndrome allele. TwinPE expands the capabilities of precision gene editing without requiring double-strand DNA breaks and synergizes with other tools to enable the correction or complementation of large or complex pathogenic alleles in human cells.

genomics↗