Small Molecule Screening Discovers Compounds that Reduce FMRpolyG Protein Aggregates and Splicing Defect Toxicity in Fragile X-Associated Tremor/Ataxia Syndrome

An Updated Canvas of the RFC1-mediated CANVAS (Cerebellar Ataxia, Neuropathy and Vestibular Areflexia Syndrome)

Proliferation of specific nucleotide sequences within the coding and non-coding regions of numerous genes has been implicated in approximately 40 neurodegenerative disorders. Cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS), a neurodegenerative disorder, is distinguished by a pathological triad of sensory neuropathy, bilateral vestibular areflexia and cerebellar impairments. It manifests in adults gradually and is autosomal recessive and multi-system ataxia. Predominantly, CANVAS is associated with biallelic AAGGG repeat expansions in intron 2 of the RFC1 gene. Although various motifs have been identified, only a subset induces pathological consequences, by forming stable secondary structures that disrupt gene functions both in vitro and in vivo. The pathogenesis of CANVAS remains a subject of intensive research, yet its precise mechanisms remain elusive. Herein, we aim to comprehensively review the epidemiology, clinical ramifications, molecular mechanisms, genetics, and potential therapeutics in light of the current findings, extending an overview of the most significant research on CANVAS.

Mapping of repeat-associated non-AUG (RAN) translation knowledge: A bibliometric analysis

Over 50 genetic human disorders are attributed to the irregular expansion of microsatellites. These expanded microsatellite sequences can experience bidirectional transcription, leading to new reading frames. Beyond the standard AUG initiation or adjacent start codons, they are translated into proteins characterized by disease-causing amino acid repeats through repeat-associated non-AUG translation. Despite its significance, there's a discernible gap in comprehensive and objective articles on RAN translation. This study endeavors to evaluate and delineate the contemporary landscape and progress of RAN translation research via a bibliometric analysis. We sourced literature on RAN translation from the Web of Science Core Collection. Utilizing two bibliometric analysis tools, CiteSpace and VOSviewer, we gauged individual impacts and interactions by examining annual publications, journals, co-cited journals, countries/regions, institutions, authors, and co-cited authors. Following this, we assessed the co-occurrence and bursts of keywords and co-cited references to pinpoint research hotspots and trending in RAN translation. Between 2011 and 2022, 1317 authors across 359 institutions from 34 countries/regions contributed to 250 publications on RAN translation, spread across 118 academic journals. This article presents a systematic, objective, and comprehensive analysis of the current literature on RAN translation. Our findings emphasize that mechanisms related to C9orf72 ALS/FTD are pivotal topics in the realm of RAN translation, with cellular stress and the utilization of small molecule marking the trending research areas.

Native functions of short tandem repeats

Over a third of the human genome is comprised of repetitive sequences, including more than a million short tandem repeats (STRs). While studies of the pathologic consequences of repeat expansions that cause syndromic human diseases are extensive, the potential native functions of STRs are often ignored. Here, we summarize a growing body of research into the normal biological functions for repetitive elements across the genome, with a particular focus on the roles of STRs in regulating gene expression. We propose reconceptualizing the pathogenic consequences of repeat expansions as aberrancies in normal gene regulation. From this altered viewpoint, we predict that future work will reveal broader roles for STRs in neuronal function and as risk alleles for more common human neurological diseases.

Targeting strategies for modulating pre-mRNA splicing with small molecules: Recent advances

The concept of using small molecules to therapeutically modulate pre-mRNA splicing was validated with the US Food and Drug Administration (FDA) approval of Evrysdi® (risdiplam) in 2020. Since then, efforts have continued unabated toward the discovery of new splicing-modulating drugs. However, the drug development world has evolved in the 10 years since risdiplam precursors were first identified in high-throughput screening (HTS). Now, new mechanistic insights into RNA-processing pathways and regulatory networks afford increasingly feasible targeted approaches. In this review, organized into classes of biological target, we compile and summarize small molecules discovered, devised, and developed since 2020 to alter pre-mRNA splicing.

A comprehensive review of methods to study lncRNA-protein interactions in solution

The long non-coding RNAs (lncRNAs) other than rRNA and tRNA were earlier assumed to be 'junk genomic material'. However, recent advancements in genomics methods have highlighted their roles not only in housekeeping but also in the progression of diseases like cancer as well as viral infections. lncRNAs owing to their length, have both short-range and long-range interactions resulting in complex folded structures that recruit various biomolecules enabling lncRNAs to undertake their various biological functions. Using cell lysate pull-down assays increasing number of lnRNAs-interacting proteins are being identified. These interactions can be further exploited to develop targeted novel therapeutic strategies to inhibit lncRNA-protein interactions. This review attempts to succinctly techniques that can identify and characterize the lnRNAs-protein interactions (i.e. affinity, stoichiometry, and thermodynamics). Furthermore, using other sophisticated biophysical techniques, one can also perform size estimations, and determine low-resolution structures. Since these methods study the biomolecules in solution, large-scale structural observations can be performed in real-time. This review attempts to briefly introduce the readers to biochemical and biophysical techniques, such that they can utilize these methods to obtain a holistic characterization of the biomolecules of interest. Additionally, it should be noted that the use of these methods is not limited to the characterization of the interacting molecules but can also be used to determine the efficacy of the therapeutic molecules to disrupt these interactions.

Interactions of amyloid coaggregates with biomolecules and its relevance to neurodegeneration

The aggregation of amyloidogenic proteins is a pathological hallmark of various neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In these diseases, oligomeric intermediates or toxic aggregates of amyloids cause neuronal damage and degeneration. Despite the substantial effort made over recent decades to implement therapeutic interventions, these neurodegenerative diseases are not yet understood at the molecular level. In many cases, multiple disease-causing amyloids overlap in a sole pathological feature or a sole disease-causing amyloid represents multiple pathological features. Various amyloid pathologies can coexist in the same brain with or without clinical presentation and may even occur in individuals without disease. From sparse data, speculation has arisen regarding the coaggregation of amyloids with disparate amyloid species and other biomolecules, which are the same characteristics that make diagnostics and drug development challenging. However, advances in research related to biomolecular condensates and structural analysis have been used to overcome some of these challenges. Considering the development of these resources and techniques, herein we review the cross-seeding of amyloidosis, for example, involving the amyloids amyloid β, tau, α-synuclein, and human islet amyloid polypeptide, and their cross-inhibition by transthyretin and BRICHOS. The interplay of nucleic acid-binding proteins, such as prions, TAR DNA-binding protein 43, fused in sarcoma/translated in liposarcoma, and fragile X mental retardation polyglycine, with nucleic acids in the pathology of neurodegeneration are also described, and we thereby highlight the potential clinical applications in central nervous system therapy.