Biology subjects

Olson, J. A.

Publications and source records attributed to Olson, J. A..

3 recordsLinked to original sources

bioRxiv2026

Profiling the CFTR Variant Selectivity and Off-Target Interactions of VX-121

More than 1,200 variants of the cystic fibrosis transmembrane conductance regulator gene (CFTR) are associated with cystic fibrosis (CF), an autosomal recessive pulmonary disease affecting over 100,000 people. Most people with CF bear a common CFTR variant (F508del) that can be treated with therapeutics containing "correctors" that suppress the misfolding of the CFTR chloride channel. However, the pharmacological responsiveness of other rare CF variants can vary tremendously. The approval of VX-121, a VX-445 analog that serves as a key component of AlyftrekTM, potentially provides a new therapeutic option for those with rare CF variants. Nevertheless, it remains unclear whether VX-121 offers superior rescue across the entire spectrum of rare CF variants. In this work, we use deep mutational scanning (DMS) to survey the impact of VX-121 on the plasma membrane expression of 232 rare CF variants. Our results show that VX-121 generally enhances CF variant expression more than VX-445 and is most potent towards variants with mutations in the first membrane spanning domain (MSD1). However, we identify one variant (Y1032C) with diminished proteostatic and functional selectivity for VX-121 relative to VX-445. Computational docking suggests that the native Y1032 side chain forms favorable interactions with VX-121 that are disrupted by this mutation in a manner that alters its coordination. Finally, using photo-crosslinking, we show that VX-121 avoids a key off-target interaction of VX-445. Together, our findings provide new insights into the similarities and differences between current approved CF therapeutics.

pharmacology and toxicology↗

bioRxiv2025

General Trends in the Calnexin-Dependent Expression and Pharmacological Rescue of Clinical CFTR Variants

Cystic Fibrosis (CF) is a genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Though most people with CF have one or two copies of the {Delta}F508 mutation, there are hundreds of other distinct CF mutations that vary in their mechanistic effects and response to therapeutics. Endogenous chaperones are known to have divergent effects on the druggability of CF variants. Nevertheless, it remains unclear how this proteostatic modulation is related to the underlying mechanistic effects of distinct classes of CF mutations. Here, we survey the effects of a previously discovered effector (calnexin, CANX) on the expression and pharmacological rescue of 232 CF variants using deep mutational scanning. We find that CANX is generally required for robust plasma membrane expression of the CFTR protein-particularly for CF variants that perturb its second nucleotide binding domain. CANX also appears to be critical for the pharmacological rescue of CF variants with poor basal expression. Though corrector selectivity is generally dictated by the properties of mutations, we find that CANX enhances the sensitivity of CF variants within a domain swapped region of membranes spanning domain 2 to the type III corrector VX-445. Overall, mutagenic trends suggest CANX modulates the later stages of CFTR assembly and disproportionately affects variants bearing mutations within the C-terminal domains. Interestingly, we find that the loss of CANX results in widespread perturbations of CF variant interactomes and that the proteostatic effects of CANX are generally decoupled from changes in CFTR activity. Together, our findings reveal how the proteostasis machinery may shape the variant-specific effects of corrector molecules.

biochemistry↗

bioRxiv2024

Proteostasis Landscapes of Selective versus Poorly Responsive CFTR Variants Reveals Structural Vulnerabilities to Correction

Cystic Fibrosis (CF) is a lethal genetic disorder caused by variants in CF transmembrane conductance regulator (CFTR). Many variants are treatable with correctors, which enhance the folding and trafficking of CFTR. However, approximately 3% of persons with CF harbor poorly responsive variants. Here, we used affinity purification mass spectrometry proteomics to profile the protein homeostasis (proteostasis) changes of CFTR variants during correction to assess modulated interactions with protein folding and maturation pathways. Responsive variant interactions converged on similar proteostasis pathways during correction. In contrast, poorly responsive variants subtly diverged, revealing a partial restoration of protein quality control surveillance and partial correction. Computational structural modeling showed that corrector VX-445 failed to confer enough NBD1 stability to poor responders. NBD1 secondary stabilizing mutations rescued poorly responsive variants, revealing structural vulnerabilities in NBD1 required for treating poor responders. Our study provides a framework for discerning the underlying protein quality control and structural defects of CFTR variants not reached with existing drugs to expand therapeutics to all susceptible CFTR variants. SIGNIFICANCE STATEMENTCystic Fibrosis (CF) is a lethal genetic disease with variants leading to misfolding of an anion channel protein. Enhancing productive channel folding using a novel class of small molecules called correctors has emerged as the current CF treatment paradigm. However, correctors fail to reach all patient variants. Using high throughput interactomics, Rosetta simulations, and biochemical trafficking assays, this study demonstrates poorly responsive CF variants experience diverse misfolding pathways caused by structural defects in the core of a nucleotide-binding domain. Stabilizing secondary mutations in this domain rescues poorly responsive variants, paving the way for mechanistic-based therapeutic development for untreatable CF variants and future protein misfolding corrector drugs. COMPETING INTERESTSThe authors declare no competing interests.

biochemistry↗