Summary: A new study identifies a novel strategy to treat proteinopathies—conditions caused by toxic buildup of misfolded proteins, including Alzheimer’s, Parkinson’s and prion diseases—by remodeling nuclear speckles, small membrane-less structures in the cell nucleus that regulate protein quality control. The research shows that pyrvinium pamoate, an FDA-approved antiparasitic, reduces the surface tension of nuclear speckles, changing their shape and enhancing cellular proteostasis.
In cultured neurons and animal disease models, treatment with pyrvinium pamoate sharply reduced pathological protein accumulation, restored cellular health and improved mobility. These findings, led by researchers at the University of Pittsburgh and published in Nature Communications, open a new direction for neurodegenerative disease research and point toward potential clinical translation.
Key Facts:
- Novel mechanism: Pyrvinium pamoate lowers the surface tension of nuclear speckles, reshaping them in ways that globally enhance expression of genes involved in protein quality control.
- Robust effects: The compound reduced tau protein aggregates by roughly 70% in neuronal models and improved functional outcomes in fly and retinal disease models.
- Wide therapeutic potential: Because nuclear speckles broadly influence proteostasis-related gene networks, this approach may be applicable to multiple proteinopathies, from Alzheimer’s disease to retinitis pigmentosa.
Source: University of Pittsburgh
Targeting nuclear speckles presents a fresh therapeutic avenue for proteinopathies
Nuclear speckles are membrane-less organelles inside the nucleus that coordinate RNA processing and influence production, folding and degradation of proteins—a process known as proteostasis. The research team, led by Bokai Zhu, Ph.D., at the University of Pittsburgh Aging Institute, previously showed that speckle shape correlates with function: more spherical speckles are associated with poorer proteostasis, while less spherical, more spread-out speckles align with improved protein handling.
Building on that insight, Zhu and colleagues screened hundreds of FDA-approved compounds to identify drugs that alter nuclear speckle sphericity. Pyrvinium pamoate, a medication originally approved for pinworm infection, emerged as a clear hit: it reduced speckle surface tension, reshaped speckles away from their round morphology, and enhanced proteostasis gene programs in cells.
“Our results suggest that dysregulation of nuclear speckles contributes to neuronal degeneration across multiple disorders,” said Zhu. “Rehabilitating speckle structure is a conceptually new and promising strategy for intervention.”
Effects in disease models
To evaluate therapeutic potential, the team tested pyrvinium pamoate in multiple preclinical models. In mouse neurons engineered to express human tau, a protein that aggregates in tauopathies, the drug lowered pathological tau levels by about 70%. Human neurons bearing a frontotemporal dementia-associated tau mutation displayed distorted nuclear speckles and elevated tau; low doses of pyrvinium pamoate restored normal speckle shape and sharply reduced tau without inducing cellular stress or toxicity.
Collaborations expanded the work into whole-animal and tissue models. In fruit fly models of tauopathy, where motor decline is assessed by climbing ability, flies treated with pyrvinium pamoate showed markedly improved locomotion as larvae and adults, indicating functional rescue. In cultured mouse retinas carrying a rhodopsin mutation that mimics retinitis pigmentosa, the drug also protected retinal cells from degeneration by improving protein clearance pathways.
Distinct mechanism: lowering speckle surface tension
To understand how the compound acts at the biophysical level, the researchers used optical tweezers and other precision assays. Nuclear speckles normally resist deformation because of relatively high surface tension. Pyrvinium pamoate dramatically lowered that surface tension, allowing speckles to spread and more readily associate with chromosomal regions that control gene expression. This increased contact appears to upregulate hundreds of genes that coordinate protein quality control, including autophagy and ubiquitin–proteasome pathways.
Mechanistically, the drug interacts with the intrinsically disordered region of the nuclear speckle scaffold protein SON, which contributes to reduced interfacial tension and altered speckle dynamics. Because nuclear speckles exert broad transcriptional control, modulating their physical properties produces wide-ranging effects on proteostasis—distinct from traditional drugs that act on single receptors or enzymes.
“This was the decisive experiment,” said Zhu. “Instead of targeting a single molecular receptor, pyrvinium pamoate shifts the biophysical state of nuclear condensates, enabling a global reprogramming of proteostasis gene expression. That broad action likely underlies the compound’s pronounced efficacy in our models.”
The authors report that aberrant nuclear speckle morphology, diminished protein quality control and elevated YAP1 transcriptional activity are observable in human tauopathy samples, supporting the clinical relevance of their findings. Based on the preclinical data, Zhu and colleagues plan to advance this approach toward human trials to test whether pyrvinium pamoate or related compounds can safely and effectively treat proteinopathies.
Contributors to the study include Xu Chen, Ph.D., Yuren Tao, William Dion, Ph.D., Bennett Van Houten, Ph.D., Yuanyuan Chen, Ph.D., and a team of researchers from the University of Pittsburgh and collaborating institutions. The work offers proof of principle that rehabilitating nuclear speckles can alleviate proteinopathies by enhancing global protein quality control mechanisms.
About this neurodegeneration research news
Author: Anastasia Gorelova
Source: University of Pittsburgh
Contact: Anastasia Gorelova – University of Pittsburgh
Image: The image is credited to Neuroscience News
Original Research: Open access. “SON-dependent nuclear speckle rehabilitation alleviates proteinopathies” by Bokai Zhu et al., published in Nature Communications.
Abstract
SON-dependent nuclear speckle rehabilitation alleviates proteinopathies
Existing therapies that focus on single protein quality control pathways have limited success in treating proteinopathies, underscoring the need for a druggable target that can modulate proteostasis on a global scale. Building on prior work identifying nuclear speckles as key membrane-less organelles for transcriptional control of proteostasis, this study tests whether rehabilitating nuclear speckles can alleviate proteinopathies.
The authors identify pyrvinium pamoate as a nuclear speckle rehabilitator that increases expression of protein quality control genes and suppresses YAP1 transcriptional activity by reducing the surface/interfacial tension of nuclear speckle condensates through interaction with the intrinsically disordered region of the scaffold protein SON.
In preclinical models, nanomolar concentrations of pyrvinium pamoate protect against retinal degeneration and tauopathy primarily by promoting autophagy and ubiquitin–proteasome activity in a SON-dependent manner, without triggering cellular stress responses.
Aberrant nuclear speckle morphology, reduced protein quality control and increased YAP1 activity are observed in human tauopathies. This study provides proof of principle that targeting nuclear speckles can ameliorate proteinopathies by broadly restoring proteostasis regulation.