Targeting Pathological Tau by Small Molecule Inhibition of the Poly(A):MSUT2 RNA–Protein Interaction

Abstract

Neurofibrillary tangles composed of aberrantly aggregating tau protein are a hallmark of Alzheimer’s disease and related dementia disorders. Recent work has shown that mammalian suppressor of tauopathy 2 (MSUT2), also named ZC3H14 (Zinc Finger CCCH-Type Containing 14), controls accumulation of pathological tau in cultured human cells and mice. Knocking out MSUT2 protects neurons from neurodegenerative tauopathy and preserves learning and memory. MSUT2 protein functions to bind polyadenosine [poly­(A)] tails of mRNA through its C-terminal CCCH type zinc finger domains, and loss of CCCH domain function suppresses tauopathy in Caenorhabditis elegans and mice. Thus, we hypothesized that inhibiting the poly­(A):MSUT2 RNA–protein interaction would ameliorate pathological tau accumulation. Here we present a high-throughput screening method for the identification of small molecules inhibiting the poly­(A):MSUT2 RNA–protein interaction. We employed a fluorescent polarization assay for initial small molecule discovery with the intention to repurpose hits identified from the NIH Clinical Collection (NIHCC). Our drug repurposing development workflow included validation of hits by dose–response analysis, specificity testing, orthogonal assays of activity, and cytotoxicity. Validated compounds passing through this screening funnel will be evaluated for translational effectiveness in future studies. This preclinical drug development pipeline identified diverse FDA approved drugs duloxetine, saquinavir, and clofazimine as potential repurposing candidates for reducing pathological tau accumulation.

Zinc Finger Proteins in Neuro-Related Diseases Progression

“…This is similar to the way in which SET is overexpressed in over half of breast cancers, resulting in inhibition of PP2A and subsequent activation of the transcription factor c-MYC by phosphorylation at serine 62 (S62) ( Janghorban et al, 2014 ). Meanwhile, the mammalian suppressor of tauopathy 2 protein (MSUT2), a poly(A) RNA binding protein, functions to bind poly adenosine [poly(A)] tails of mRNA through its C-terminal CCCH type zinc finger domains, which leading to the formation of pathological tau protein ( Baker et al, 2020 ). Studies have shown that MSUT2 knockout has anti-inflammatory and neuroprotective effects in a mouse model.…”

“…Loss of function of MSUT2 can reduce the formation of tau protein and protect the loss of neurons, but the molecular mechanism is still unclear. It can only be said that this may be related to the joint action of MSUT2 and its antagonistic canonical nuclear poly(A) binding protein PABPN1 ( Wheeler et al, 2019 ; Baker et al, 2020 ).…”

Iridium/graphene nanostructured catalyst for the N-alkylation of amines to synthesize nitrogen-containing derivatives and heterocyclic compounds in a green process

“…Due to its antihistamine effect, it can also treat severe itching and hyperalgesia, and can even be used as a drug to relieve symptoms of opioid withdrawal; in addition, hydroxyzine derivatives are also research objects for the treatment of viral infections. 16 So far, there are many methods for producing hydroxyzine, but most of them are stoichiometric reactions through a long production process. Scheme 4a is a patented process for industrial production of hydroxyzine, which includes at least three main steps.…”

AlphaScreen Identifies MSUT2 Inhibitors for Tauopathy-Targeting Therapeutic Discovery

“…We have previously described an FP assay for poly(A)–MSUT2 binding. 40 Unbound fluorescein-labeled RNA rapidly rotates in solution compared with MSUT2-bound RNA. This results in a significant measurable reduction in polarized light emission and is used to determine the small-molecule inhibition potential.…”