Researchers have identified the first "nearly universal" pharmacological chaperone capable of stabilizing mutated proteins regardless of where mutations occur, offering new hope for treating rare genetic diseases. A study published in Nature Structural & Molecular Biology demonstrates that tolvaptan, an oral medication already approved for kidney conditions, can restore function to 87% of disease-causing mutations in the vasopressin V2 receptor.
Comprehensive Mutation Analysis Reveals Broad Efficacy
The research team engineered seven thousand versions of the vasopressin V2 receptor (V2R), creating all possible mutated variants in laboratory conditions. V2R plays a critical role in normal kidney function, and faulty mutations prevent kidney cells from responding to the hormone vasopressin. This leads to the inability to concentrate urine, resulting in excessive thirst and large volumes of dilute urine—hallmarks of nephrogenic diabetes insipidus (NDI), also known as arginine vasopressin resistance.
When researchers examined mutations specifically observed in patients, they found that tolvaptan restored receptor levels to near-normal for 87% of destabilized mutations. This included 60 out of 69 known disease-causing mutations and 835 out of 965 predicted disease-causing mutations.
Mechanism of Universal Protein Stabilization
Dr. Taylor Mighell, first author of the study and postdoctoral researcher at the Centre for Genomic Regulation (CRG) in Barcelona, explains the mechanism: "Inside the cell, V2R travels through a tightly managed traffic system. Mutations cause a jam, so V2R never reaches the surface. Tolvaptan steadies the receptor for long enough to allow the cell's quality control system to wave it through."
The research builds on previous findings showing that most mutations affect protein function by altering stability, making the entire structure less stable than normal. Tolvaptan works regardless of mutation location because proteins naturally switch between folded and unfolded forms. Most V2R mutations increase the likelihood of the unfolded form, but when tolvaptan binds to V2R, it favors the folded form over the unfolded one.
Addressing Rare Disease Treatment Challenges
The findings could help tackle longstanding challenges in rare disease medicine. Rare diseases affect fewer than 1 in 2,000 people individually, but collectively impact around 300 million people worldwide across thousands of different conditions. Most rare diseases result from DNA mutations, and the same gene can be mutated in many ways, meaning patients with "the same" rare disease often have different mutations driving their condition.
This genetic diversity creates significant obstacles for drug development. Because few individuals share the same mutation, developing targeted therapies is slow and commercially unattractive. Most current treatments manage symptoms rather than addressing the root cause of rare diseases.
Previous studies indicate that between 40% and 60% of rare-disease-causing mutations affect protein stability. If future studies confirm that rescued receptors function normally, this research offers a new roadmap for rare disease drug development—targeting protein stabilization rather than individual mutations.
Implications for GPCR-Related Diseases
V2R belongs to the human body's largest receptor family, G-protein-coupled receptors (GPCRs), which includes roughly 800 genes that serve as targets for about one-third of all approved drugs. Many rare and common diseases arise when GPCRs fail to fold or traffic correctly to the cell surface, even though their signaling components remain largely intact.
ICREA Research Professor Ben Lehner, Group Leader at the Wellcome Sanger Institute and Centre for Genomic Regulation, concludes: "If the behavior we found holds for other members of GPCR family, drug developers could swap spending years of hunting for bespoke therapeutic molecules and try looking for general or universal pharmacological chaperones instead, greatly accelerating the drug development pipeline for many genetic diseases."
Clinical Significance for NDI Patients
Nephrogenic diabetes insipidus affects roughly one in 25,000 people, causing debilitating symptoms that significantly impact quality of life. The demonstration that an already-approved medication can potentially treat 87% of disease-causing mutations represents a significant advancement for this patient population and establishes a precedent for treating other rare genetic diseases through protein stabilization approaches.
