Biology subjects

Lueck, J. D.

Publications and source records attributed to Lueck, J. D..

12 recordsLinked to original sources

bioRxiv2025

Elimination of myotonia improves myopathy in a muscleblind knockout model of myotonic dystrophy

A cardinal sign of myotonic dystrophy type 1 (DM1) is slow of muscle relaxation after voluntary contraction known as myotonia. Myotonia results from mis-regulated splicing of chloride channel 1 (ClC-1), leading to loss of channel function and runs of involuntary action potentials in muscle fibers. Heralding the onset of weakness, myotonia is often the first symptom of DM1, and raising the possibility that muscle hyperexcitability promotes the subsequent development of myopathy. We used genome editing to test this possibility by deleting the alternatively spliced and frameshift inducing ClC-1 exon 7a (E7a) in the Mbnl1 knockout model of DM1. Although several ClC-1 exons exhibit mis-regulated splicing in DM1, deletion of this single cryptic exon was sufficient to restore ClC-1 function and eliminate myotonia systemically and permanently. As determined by long-read sequencing, deletion of E7a reduced the frequency of other splicing defects in ClC-1 transcripts, likely as a passive consequence of restoring reading frame and nonsense surveillance. Furthermore, we observed significantly improved muscle force generation, fiber-type distribution, and histology, and partial restoration of the muscle transcriptome, including differential gene expression and alternative splicing, in non-myotonic Mbnl1 knockout mice. These results suggest that E7a inclusion is a lynchpin splice event that contributes to skeletal myopathy, highlighting myotonia as a therapeutic target and an outcome of interest in DM1. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=171 SRC="FIGDIR/small/677400v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@101b333org.highwire.dtl.DTLVardef@9be92corg.highwire.dtl.DTLVardef@1e95c88org.highwire.dtl.DTLVardef@1b9eeee_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2025

Anticodon Edited Transfer RNAs (ACE-tRNAs) Encoded as Therapeutic Nonviral Minimal DNA Vectors

Nonsense mutations, resulting from a premature termination codon (PTC), make up [~]11% of all genetic lesions causing disease, affecting millions of people worldwide. Nonsense suppressor anticodon-edited tRNAs (ACE-tRNAs) have emerged as a therapeutic modality for the rescue of PTCs. Delivery of ACE-tRNAs in vivo has been achieved by adeno-associated viral vector and RNA-lipid nanoparticle, however due to drawbacks associated with these approaches, DNA delivery remains an attractive approach. DNA-based approaches afford ease of manufacturing at a relatively low cost and exhibit improved therapeutic durability and safety as compared to viral vector-or RNA-based approaches. Due to the small size of human tRNA genes employed as ACE-tRNAs, in principle, DNA vectors <200 base pairs (bp) in size (minivectors) could be utilized for delivery of actively transcribed ACE-tRNAs. Here we demonstrate that linear DNA ACE-tRNA vectors as small as 200 bp effectively suppress several nonsense mutations in CFTR and REP1, and that ACE-tRNA minivectors display significantly improved bioavailability, reduced innate immune burden, and superior biostability as compared to conventional plasmid DNA vectors.

molecular biology↗

bioRxiv2025

Anticodon-edited tRNA enables translational readthrough of COL4A5 premature termination codons

Alport syndrome is caused by variants in COL4A3, COL4A4, or COL4A5, which encode the 345 chains of type IV collagen. These variants result in defects in the glomerular basement membrane (GBM) and impaired kidney function. Nonsense variants result in truncated proteins lacking the NC1 domain, thereby preventing proper GBM assembly and function and causing the most severe forms of the disease. Restoring full-length protein expression represents a potential therapeutic strategy for Alport syndrome and related disorders. Anticodon-edited transfer RNAs (ACE-tRNAs), which promote premature termination codon (PTC) readthrough, have shown promise in diseases such as cystic fibrosis, but their application in Alport syndrome remains unexplored. To assess the potential of ACE-tRNAs for PTC readthrough of COL4A5 nonsense variants, we employed a C-terminal NanoLuc-fused COL4A5 reporter system in which luminescence is produced only upon full-length protein translation. We introduced ACE-tRNAs into HeLa and 293T cells expressing one of four COL4A5 nonsense variants (S36X, R1563X, S1632X, and R1683X) identified in patients with X-linked Alport syndrome. Readthrough efficiency was evaluated via NanoLuc luminescence and western blotting. Furthermore, we assessed the efficiency of ACE-tRNA-restored 345 heterotrimer formation using a split NanoLuc-based assay. Our results show that application of ACE-tRNAs led to restored C-terminal luminescence across all four COL4A5 nonsense variants, indicating successful readthrough and full-length translation. Moreover, the restored COL4A5 proteins formed 345 heterotrimers. These findings support ACE-tRNA-mediated nonsense suppression as a promising therapeutic strategy for Alport syndrome, with the potential to restore GBM integrity in patients harboring nonsense variants.

genetics↗

bioRxiv2024

Mechanism-based approach in designing patient-specific combination therapies for nonsense mutation diseases

Premature termination codon (PTC) diseases, arising as a consequence of nonsense mutations in a patients DNA, account for approximately 12% of all human disease mutations. Currently there are no FDA approved treatments for increasing PTC readthrough in nonsense mutation diseases, although one translational readthrough inducing drug, ataluren, has had conditional approval for treatment of Duchenne muscular dystrophy in Europe and elsewhere for 10 years. Ataluren displays consistent low toxicity in clinical trials for treatment of several different PTC diseases, but its therapeutic effects on such diseases are inconsistent. The identity of the stop codon and its sequence context are major determinants of PTC readthrough efficiency in both the absence and presence of nonsense suppressors. Previously we have shown that ataluren stimulates readthrough exclusively by competitively inhibiting release factor complex (RFC, eRF1.eRF3.GTP)-dependent catalysis of translation termination. Here, using an in vitro reconstituted system (PURE-LITE) and both ensemble and single molecule assays, we demonstrate that PTC identity and the immediately adjacent mRNA sequence contexts modulate the catalytic activity of RFC in terminating peptide elongation. Such modulation largely determines the effectiveness of ataluren in stimulating readthrough, whether added alone or in combination with either the aminoglycoside G418 or an anticodon edited aa-tRNA, each of which stimulate readthrough by mechanisms orthogonal to that of ataluren. Our results provide an attractive rationale for the variability of ataluren effectiveness in stimulating readthrough in clinical trials. Patients harboring a PTC mutation with a sequence context promoting strong interaction with RFC are predicted to be resistant to ataluren, whereas ataluren treatment should be more effective for patient sequences conferring weaker interaction with RFC.

biochemistry↗

bioRxiv2024

Gz Enhanced Signal Transduction assaY (GZESTY) for GPCR deorphanization

G protein-coupled receptors (GPCRs) are key pharmacological targets, yet many remain underutilized due to unknown activation mechanisms and ligands. Orphan GPCRs, lacking identified natural ligands, are a high priority for research, as identifying their ligands will aid in understanding their functions and potential as drug targets. Most GPCRs, including orphans, couple to Gi/o/z family members, however current assays to detect their activation are limited, hindering ligand identification efforts. We introduce GZESTY, a highly sensitive, cell-based assay developed in an easily deliverable format designed to study the pharmacology of Gi/o/z-coupled GPCRs and assist in deorphanization. We optimized assay conditions and developed an all-in-one vector employing novel cloning methods to ensure the correct expression ratio of GZESTY components. GZESTY successfully assessed activation of a library of ligand-activated GPCRs, detecting both full and partial agonism, as well as responses from endogenous GPCRs. Notably, with GZESTY we established the presence of endogenous ligands for GPR176 and GPR37 in brain extracts, validating its use in deorphanization efforts. This assay enhances the ability to find ligands for orphan GPCRs, expanding the toolkit for GPCR pharmacologists.

pharmacology and toxicology↗

bioRxiv2024

Anticodon Engineered Transfer RNAs (ACE-tRNAs) are a Platform Technology for Suppressing Nonsense Mutations

Nonsense mutations arise from single nucleotide substitutions that result in premature termination codons (PTCs). PTCs result in little to no full-length protein production and loss of mRNA expression through the nonsense-mediated mRNA decay (NMD) pathway. We demonstrate that anticodon engineered (ACE-) tRNAs efficiently suppress the most prevalent cystic fibrosis (CF) causing PTCs, promoting significant rescue of endogenous cystic fibrosis transmembrane conductance regulator (CFTR) transcript abundance and channel function in different model systems. We demonstrate that our best-performing ACE-tRNA, that decodes all UGA PTCs to a leucine amino acid, markedly rescues CFTR channel function from the most prevalent CF causing PTCs that arise from non-leucine encoding codons. Using this single ACE-tRNA variant, we demonstrate significant rescue of CFTR channel function in an immortalized airway cell line and two different primary CF patient-derived intestinal cell models with CFTR nonsense mutations. Thus, ACE-tRNAs have promise as a platform therapeutic for CF and other nonsense-associated diseases.

molecular biology↗

bioRxiv2024

Optimization of Anticodon Edited Transfer RNAs (ACE-tRNAs) Function in Translation for Suppression of Nonsense Mutations

Nonsense suppressor tRNAs or AntiCodon-Edited tRNAs (ACE-tRNAs) have long been envisioned as a therapeutic approach to overcome genetic diseases resulting from the introduction of premature stop codons (PTCs). The ACE-tRNA approach for the rescue of PTCs has been hampered by ineffective delivery through available modalities for gene therapy. Here we have screened a series of ACE-tRNA expression cassette sequence libraries containing >1,800 members to optimize ACE-tRNA function and provide a roadmap for optimization in the future. By optimizing PTC suppression efficiency of ACE-tRNAs, we have decreased the amount of ACE-tRNA required by [~]16-fold for the most common cystic fibrosis-causing PTCs.

molecular biology↗

bioRxiv2023

Combinatorial chloride and calcium channelopathy in myotonic dystrophy

Myotonic dystrophy type 1 (DM1) involves misregulated alternative splicing for specific genes. We used exon or nucleotide deletion to mimic altered splicing of genes central to muscle excitation-contraction coupling processes in mice. Mice with forced-skipping of exon 29 in CaV1.1 calcium channel combined with loss of ClC-1 chloride channel function showed a markedly reduced lifespan, whereas other combinations of splicing mimics did not affect survival. The Ca2+/Cl- bi-channelopathy mice exhibited myotonia, weakness, and impairment of mobility and respiration. Chronic administration of the calcium channel blocker verapamil rescued survival and improved force generation, myotonia, and respiratory function. These results suggest that Ca2+/Cl- bi-channelopathy contributes to muscle impairment in DM1 and is potentially mitigated by common clinically available calcium channel blockers. SummaryRepurposing of a calcium channel blocker extends life and mitigates muscle and respiratory dysfunction in a myotonic dystrophy type 1 Ca2+/Cl- bi-channelopathy mouse model.

physiology↗

bioRxiv2021

Efficient Suppression of Endogenous CFTR Nonsense Mutations Using Anticodon Engineered Transfer RNAs

Nonsense mutations or premature termination codons (PTCs) comprise [~]11% of all genetic lesions, which result in over 7,000 distinct genetic diseases. Due to their outsized impact on human health, considerable effort has been made to find therapies for nonsense-associated diseases. Suppressor tRNAs have long been identified as a possible therapeutic for nonsense-associated diseases, however their ability to inhibit nonsense-mediated mRNA decay (NMD) and support significant protein translation from endogenous transcripts has not been determined in mammalian cells. Here we investigated the ability of anticodon edited (ACE)-tRNAs to suppress cystic fibrosis (CF) causing PTCs in the cystic fibrosis transmembrane regulator (CFTR) gene in gene-edited immortalized human bronchial epithelial (16HBEge) cells. Delivery of ACE-tRNAs to 16HBEge cells harboring three common CF mutations G542X-, R1162X- and W1282X-CFTR PTCs significantly inhibited NMD and rescued endogenous mRNA expression. Furthermore, delivery of our highly active leucine encoding ACE-tRNA resulted in rescue of W1282X-CFTR channel function to levels that significantly exceed the necessary CFTR channel function for therapeutic relevance. This study establishes the ACE-tRNA approach as a potential stand-alone therapeutic for nonsense-associated diseases due to its ability to rescue both mRNA and full-length protein expression from PTC containing endogenous genes. One Sentence SummarySuppression of endogenous CFTR nonsense mutations by anticodon engineered tRNAs significantly increases mRNA expression and channel function.

molecular biology↗

bioRxiv2019

β11-12 linker isomerization governs Acid-sensing ion channel desensitization and recovery

Acid-sensing ion channels (ASICs) are neuronal sodium-selective channels activated by reductions in extracellular pH. Structures of the three presumptive functional states, high-pH resting, low-pH desensitized, and toxin-stabilized open, have all been solved for chicken ASIC1. These structures, along with prior functional data, suggest that the isomerization or flipping of the {beta}11-12 linker in the extracellular, ligand-binding domain is an integral component of the desensitization process. To test this, we combined fast perfusion electrophysiology, molecular dynamics simulations and state-dependent non-canonical amino acid cross-linking. We find that both desensitization and recovery can be accelerated by orders of magnitude by mutating resides in this linker or the surrounding region. Furthermore, desensitization can be suppressed by trapping the linker in the resting state, indicating that isomerization of the {beta}11-12 linker is not merely a consequence of, but a necessity for the desensitization process in ASICs.

neuroscience↗

bioRxiv2018

Engineered transfer RNAs for suppression of premature termination codons

Premature termination codons (PTCs) are responsible for 10-15% of all inherited disease. PTC suppression during translation offers a promising approach to treat a variety of genetic disorders, yet small molecules that promote PTC read-through have yielded mixed performance in clinical trials. We present a high-throughput, cell-based assay to identify anticodon engineered transfer RNAs (ACE-tRNA) which can effectively suppress in-frame PTCs and faithfully encode their cognate amino acid. In total, we identified ACE-tRNA with a high degree of suppression activity targeting the most common human disease-causing nonsense codons. Genome-wide transcriptome ribosome profiling of cells expressing ACE-tRNA at levels which repair PTC indicate that there are limited interactions with translation termination codons. These ACE-tRNAs display high suppression potency in mammalian cells, Xenopus oocytes and mice in vivo, producing PTC repair in multiple genes, including disease causing mutations within the cystic fibrosis transmembrane conductance regulator (CFTR).

molecular biology↗

bioRxiv2016

Engineered tRNA suppression of a CFTR nonsense mutation

Ten percent of human diseases are caused by nonsense mutations that lead to premature truncation of the protein reading frame. Small molecules that promote read-through of such PTC have significant clinical promise but current iterations suffer from low in vivo efficacy and the nonselective amino acid incorporation. Alternatively, while gene-modifying approaches, such as CRISPR/Cas9, represent a long-term solution, such treatments may be far from reaching the clinical setting. Building on previous work by our group and others, we describe a tRNA engineering approach that enables the conversion of an in frame nonsense stop mutation to the naturally occurring amino acid, thus rescuing the full-length wild type protein. Data is presented demonstrating the functionality of the approach with the rescue of CFTR W1282X, a human mutation that causes cystic fibrosis (CF). The stringency of the approach is confirmed by mass spectrometry in a model protein indicating the encoding of only tryptophan at the TGA suppression site. The data describe the first use of an edited tRNA to repair a CF causative mutation and serve a proof of principle for the eventual use of codon-edited tRNA for the therapeutic rescue of PTC disease codons.

cell biology↗