Aug 2026· Journal of Biomedical Sciences· Vol 33· 0 citations· 100 references
Medicine
TL;DR
A primary mechanism of SLC26A4 regulation in the inner ear and kidney and of SLC26A4 loss of function in Pendred syndrome and deafness DFNB4 is described and a atomistic model of the complete SLC26A4/ZBTB16/Cullin 3/RocI complex is provided in agreement with experimental results.
Abstract
Pathogenic sequence alterations in the SLC26A4 gene, which encodes the solute carrier SLC26A4/pendrin, lead to Pendred syndrome and non-syndromic autosomal recessive deafness type B4 (DFNB4), two of the most common forms of hearing loss worldwide. Many pathogenic SLC26A4 protein variants exhibit reduced cellular levels due to ubiquitin-proteasome system (UPS)-mediated degradation, and UPS inhibition rescues their plasma membrane expression and ion transport function. However, the underlying molecular mechanisms remain unclear and may involve interactions with novel molecular partners. A candidate SLC26A4 protein partner was found by a yeast two-hybrid screening. The biological significance of this interaction has been studied by immunohistochemistry and co-localization in the mouse inner ear and kidney, co-immunoprecipitation of endogenous and recombinant proteins, Liquid Chromatography-Tandem Mass Spectrometry, and Fluorescence Resonance Energy Transfer. We identified the zinc finger and BTB domain-containing protein ZBTB16 as a novel SLC26A4-interacting partner. ZBTB16 co-localized with SLC26A4 in the outer sulcus and spiral prominence epithelial cells of the mouse cochlea and in the apical membrane of non-alpha non-beta intercalated cells of the distal nephron. ZBTB16 was found to be part of a ubiquitin-ligase complex comprising the scaffold protein Cullin 3 and the ubiquitin ligase RocI, and to bind with its C-terminal zinc finger region a unique amino acid sequence within the C-terminal Sulfate Transporter and Anti-Sigma factor Antagonist (STAS) domain of SLC26A4. This direct molecular interaction leads to increased site- and variant-specific ubiquitination and accelerated degradation of SLC26A4. Finally, using AI-based structure prediction, we provide an atomistic model of the complete SLC26A4/ZBTB16/Cullin 3/RocI complex in agreement with our experimental results. These findings describe a primary mechanism of SLC26A4 regulation in the inner ear and kidney and of SLC26A4 loss of function in Pendred syndrome and deafness DFNB4, and identify potential novel molecular targets for therapeutic intervention.
Analysis of SCA48-associated variants spanning the TPR and U-box domains indicates that SCA48 results from domain-specific disruption of CHIP's dual functions, producing varying degrees of CHIP insufficiency and/or gain-of-toxic effects that together contribute to the phenotypic diversity observed across patients.
S. Altinok, E. Paulakonis, Michael F. Almeida et al.· Journal of Biological Chemis...· 0 citations
These findings identify a primate-specific cascade linking Alu-mediated genomic rearrangements to zinc dyshomeostasis and Golgi pathology and suggest that dysregulation of the ZnT6–Golgi axis may represent a vulnerability and therapeutic target in structural variant–driven neurodegeneration and possibly in a subset of sporadic cases.
Youngsun Lee, Onju Ham, Hana Lee et al.· Signal Transduction and Targ...· 0 citations
The functions of many human proteins remain unknown, highlighting major gaps in our understanding of cellular biology. TTC33 is an evolutionarily conserved tetratricopeptide repeat (TPR) protein expressed across human tissues, whose molecular role is not defined. Here we identify the TTC33 partners using comparative label-free mass spectrometry. The TTC33-associated network (TAN) comprises WDR61, CCDC97, UNG1/2, PP2A-B55α, PHF5A, and components of the SF3B U2 spliceosomal complex. Using a combination of biochemical assays, structural modeling and molecular dynamics we show that TTC33 directly recruits WDR61 and PHF5A to assemble into a trimeric core complex (TANC), which then forms distinct interactions with either UNG1/2 or SF3B–CCDC97. Somatic TTC33 mutations at key TANC interface residues reduce complex stability and weaken the interaction network. We further show that WDR61 stabilizes TTC33 by protecting it from proteolytic degradation. Loss of network components induces genomic instability and activates DNA damage markers, including γH2AX and p53 phosphorylation.
R. Tomecki, Małgorzata Drabko, Małgorzata Siek et al.· Nature Communications· 0 citations
These findings establish a mechanistic link between mutation-induced structural dynamics and impaired PINK1–ubiquitin recognition at Ser65, providing a mutation-specific framework for understanding early mitophagy impairment in ARPD and supporting future molecular assessment and targeted therapeutic development.
Zhiguang Jia, B. Malik, Deborah Vincent et al.· Frontiers in Molecular Neuro...· 0 citations
As a key N6-methyladenosine (m6A)-binding protein, YT521-B Homology (YTH) Domain-Containing Protein 2 (YTHDC2) plays a central role in the epitranscriptomic regulatory network. This protein specifically recognizes and binds to m6A modification sites on RNA molecules through its highly conserved YTH domain. This recognition exhibits high selectivity and affinity, thereby enabling precise control over the fate of target RNAs. At the molecular level, YTHDC2 is widely involved in various stages of the RNA life cycle, including core biological processes such as RNA splicing and processing, nuclear–cytoplasmic transport, translational efficiency regulation, and RNA decay. In recent years, accumulating evidence indicates that YTHDC2 participates in a variety of pathophysiological processes in an m6A-dependent manner. However, the robustness of evidence regarding YTHDC2 is heterogeneous across disease contexts. While certain pathologies are supported by rigorous mechanistic validation, others rely primarily on expression correlations or bioinformatic analyses. This review systematically synthesizes current knowledge regarding the multifaceted roles of YTHDC2 in disease progression, prognosis, and therapy, offering a comprehensive framework to guide future investigations.
Yan-Ying Hu, Qi Zhou, Ning Xu et al.· Cells· 0 citations
β-propeller protein-associated neurodegeneration (BPAN) is the most prevalent subtype of neurodegeneration with brain iron accumulation (NBIA) and is caused by mutations in the WDR45 gene encoding the autophagy-related protein WIPI4. However, many WDR45 missense variants remain classified as variants of uncertain significance (VUS), highlighting the need for reliable functional assays to support their clinical interpretation. In this study, we identified the yeast ortholog of WDR45 and established a Saccharomyces cerevisiae-based functional complementation assay to assess the pathogenicity of WDR45 variants. We first showed that deletion of the β-propellers that bind polyphosphoinositides (PROPPIN)-encoding genes ATG18 or HSV2 causes mitochondrial dysfunction and impaired respiratory growth. Human WDR45/WIPI4 specifically rescued the respiratory defect of the atg18Δ strain, whereas WDR45B/WIPI3 complemented the hsv2Δ phenotype, establishing yeast Atg18 as the closest functional counterpart of WIPI4, thus clarifying PROPPIN orthology. We then evaluated a panel of WDR45 variants and found that benign variants restored normal growth, whereas truncating and pathogenic missense variants failed to complement the atg18Δ phenotype, validating the assay for functional variant classification. Finally, we analyzed several VUS identified in patients with clinically compatible BPAN and obtained functional evidence supporting their pathogenicity. Overall, our study establishes a simple, robust, and scalable yeast model that enables functional interpretation of WDR45 variants and improves molecular diagnosis of BPAN.
Vincent Morin, C. Durand, C. Angelini et al.· International Journal of Mol...· 0 citations
