Biology subjects

Kwon, S. C.

Publications and source records attributed to Kwon, S. C..

4 recordsLinked to original sources

bioRxiv2026

Chemical activation of mitophagy via the N-degron pathway alleviates mitochondrial neuropathies

Pharmacological activation of mitophagy offers a promising strategy to eliminate dysfunctional mitochondria. We previously identified the autophagy receptor p62/SQSTM1 as an N-recognin whose activity is enhanced by Arg/N-degrons. Here, we show that Arg/N-degrons generated by ATE1-encoded R-transferase regulate p62-mediated mitophagy by promoting its recruitment to damaged mitochondria. Structural modification of Arg/N-degrons yielded ATB1071, a 443.5-Da orally bioavailable compound that activates p62 and induces stress-selective mitophagy through both Parkin-independent pathways involving NIPSNAP1 and NIPSNAP2, and a Parkin-dependent pathway involving the substrate EBP1/PA2G4. In Ndufs4-/- mice, a Leigh syndrome (LS) model, ATB1071 induced mitophagy in the brain and exerted therapeutic benefits by reducing neuroinflammation, improving muscle strength and neuromuscular coordination, and extending lifespan. In cerebral ischemia-reperfusion (IR) model mice, ATB1071 reduced infarct volume and neuronal death, and ameliorated multiple behavioral deficits through EBP1-dependent mitophagy. Pharmacokinetic (PK) and toxicological analyses support ATB1071 as a preclinical candidate for mitochondria-associated neurological injury.

cell biology↗

bioRxiv2025

A scalable screening platform for discovering predominant miRNA target genes and druggable siRNA sequences

Programmable RNA-targeting systems, including RNA interference (RNAi) and CRISPR-Cas13, are transformative tools for research and therapeutics. However, a lack of high-resolution comparative data obscures whether these mechanistically distinct platforms share fundamental rules for target-site selection. To address this, we developed shRNAone, an engineered scaffold that eliminates processing heterogeneity to guarantee guide biogenesis at single-nucleotide precision. Deploying this platform to systematically decouple microRNA pairing rules in cellulo, we demonstrate that while seed pairing drives primary target recognition, 3'-supplementary pairing is strictly essential for specific transcript repression. Furthermore, single-nucleotide shRNAone tiling screens accurately predict siRNA efficacy and reveal clustered, highly permissive silencing hotspots localized within 3' UTRs. By mapping CasRx and PspCas13b silencing landscapes across the identical mRNA, we show that these hotspots represent intrinsic structural vulnerabilities governed by local RNA accessibility. However, while shRNAone and CasRx activity is largely restricted to the 3' UTR, PspCas13b efficiently targets the coding sequence, highlighting its unique capacity to overcome ribosome occupancy. Together, these high-resolution profiles define the shared and distinct structural barriers governing diverse RNA-targeting systems and provide a rationally designed, transcriptome-wide guide resource for PspCas13b applications.

molecular biology↗

bioRxiv2024

Cytosolic CRISPR RNA for RNA-targeting CRISPR-Cas systems

Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) technologies have evolved rapidly over the past decade with the continuous discovery of new Cas systems. In particular, RNA-targeting CRISPR-Cas13 proteins are promising single-effector systems to regulate target mRNAs without altering genomic DNA, yet the current Cas13 systems are still restrained by suboptimal efficiencies. Here, we show that U1-driven CRISPR RNAs (crRNAs) can dramatically increase the efficiency of various applications, including RNA knockdown and editing, without modifying the Cas13 protein effectors. We confirm that U1-driven crRNAs are exported into the cytoplasm, while conventional U6 promoter-driven crRNAs are mostly confined in the nucleus. Furthermore, we reveal that the end positions of crRNAs expressed by the U1 promoter are consistent regardless of different guide sequences and lengths. We also demonstrate that U1-driven crRNAs, but not U6-driven crRNAs, can efficiently repress the translation of target genes in combination with catalytically inactive Cas13 proteins. Finally, we show that U1-driven crRNAs can counteract the inhibitory effect of miRNAs. Our simple and effective engineering enables unprecedented cytosolic RNA-targeting applications.

biochemistry↗

bioRxiv2020

ERH as a component of the Microprocessor facilitates the maturation of suboptimal microRNAs

The Microprocessor complex cleaves the primary transcript of microRNA (pri-miRNA) to initiate miRNA maturation. Microprocessor is known to consist of RNase III DROSHA and dsRNA-binding DGCR8. Here we identify Enhancer of Rudimentary Homolog (ERH) as a new component of the Microprocessor. ERH binds to a conserved region in the N-terminus of DGCR8. Knockdown of ERH or deletion of the DGCR8 N-terminus results in a decrease of processing of primary miRNAs with suboptimal hairpin structures that reside in polycistronic miRNA clusters. ERH increases the processing of suboptimal pri-miR-451 in a manner dependent on its neighboring pri-miR-144. Thus, the ERH dimer may mediate "cluster assistance" in which the Microprocessor is loaded onto a poor substrate with help from a high-affinity substrate in the same cluster. Our study reveals a role of ERH in the miRNA pathway.

molecular biology↗