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Immunoreactive forms of human erythrocyte ankyrin are present in diverse cells and tissues.

Ankyrin is a polypeptide of molecular weight (MW) 200,000 which is tightly bound to the cytoplasmic surface of the human erythrocyte membrane and has been identified as the high-affinity membrane attachment protein for spectrin. This protein has also been shown to be associated with band 3 (ref. 4), the major transmembrane protein which links a cytoplasmic structural protein to an integral membrane protein. A water-soluble, 72,000-MW, proteolytic fragment of ankyrin has been purified which retains the ability to bind to spectrin, and competitively inhibits reassociation of spectrin with membranes. Monospecific antibodies directed against this fragment have been prepared and demonstrated to cross-react only with ankyrin among the erythrocyte membrane proteins. The present study reports the use of these antibodies to develop a radioimmunoassay capable of detecting femtomolar quantities of ankyrin, and demonstrates the presence of small but significant amounts of immunoreactivity in a variety of types of cells and tissues.

Blood Platelets

A Novel Nonsense Variant in Ankyrin Repeat and Sterile Alpha Motif Domain-Containing 6 Promotes Polycystic Kidney Disease in Han:SPRD- Cy Rats and Its Homozygosity Is Prenatally Lethal.

KEY POINTS: A novel nonsense variant ( mcy ) in ankyrin repeat and sterile alpha motif domain-containing 6 ( Anks6 ) promotes rapid disease progression in the Han:SPRD- Cy rat carrying a missense variant in Anks6 . mcy-/- rats exhibit prenatal lethality characterized by laterality and cardiovascular abnormalities. These findings indicate that ANKS6 nonfunction in rats leads to prenatal lethality, whereas misfunction leads to polycystic kidney disease development. BACKGROUND: Polycystic kidney disease (PKD) encompasses a group of genetic disorders characterized by the proliferation of fluid-filled renal cysts, leading to progressive renal failure and death. A key feature of PKD is its variable expressivity across patients, even when caused by the same variant, highlighting the importance of genetic background in PKD expression. METHODS: We identified an ostensibly healthy Sprague Dawley rat line with a variant that modifies PKD expressivity in Han:SPRD- Cy rats (caused by a missense variant [p.Arg717Trp] in the ankyrin repeat and sterile alpha motif domain-containing 6 [ Anks6 ] gene), which we named mcy (modifier of Cy ). We used whole-genome sequencing and segregation analysis to identify the mcy variant, quantitative PCR and mRNA sequencing to evaluate its effects on gene expression, western blotting and immunohistochemistry to assess its protein consequences, and ultrasound and histology to examine its impact on rat embryonic development. RESULTS: We identified a nonsense variant in the Anks6 gene as the genetic basis of the mcy phenotype (c.1126G>T [p.Glu376X]). Although mcy+/- rats are ostensibly healthy and do not develop PKD, mcy-/- rats exhibit laterality defects and die prenatally at E16.5 because of apparent perturbations in cardiovascular development. Notably, mcy+/-Cy+/- rats develop PKD much more rapidly than Cy+/- rats, and in a timeframe consistent with Cy-/-rats . Transcripts with the mcy variant allele seem to undergo nonsense-mediated decay, and no ANKS6 protein is detected. However, gene expression patterns in the kidneys did not differ significantly between age-matched mcy+/+ and mcy+/- rats, indicating that ANKS6 insufficiency does not cause PKD. CONCLUSIONS: We identified a novel nonsense variant in Anks6 . The findings indicate that the absence of wild-type ANKS6 accelerates PKD development in the Han:SPRD- Cy rat and that complete ANKS6 deficiency prevents normal embryonic development in rats.

Animals

The membrane attachment protein for spectrin is associated with band 3 in human erythrocyte membranes.

Ankyrin, the membrane attachment protein for human erythrocyte spectrin, is tightly linked in a 1:1 molar ratio with band 3 in detergent extracts of spectrin-depleted membranes. Ankyrin-linked band 3, which represents 10--15% of the total band 3, spans the membrane, and is nearly identical to the major band 3 by peptide analysis. Spectrin binds to solubilised ankyrin-linked band 3, but not to free band 3. A portion of band 3 remains firmly associated with detergent-extracted cytoskeletal proteins. It is concluded that a fraction of band 3 is attached to the erythrocyte cytoskeleton through association with ankyrin, which in turn is bound to spectrin.

Chromatography, Gel

Ank3 loss in adult forebrain excitatory neurons disrupts behavior, neuronal activity, membrane proteome, and myelination.

ANK3, encoding the scaffolding protein ankyrin-G, is a major risk gene for bipolar disorder and schizophrenia, but its cellular and circuit-level mechanisms remain poorly defined. Here, we demonstrate that deletion of Ank3 in forebrain excitatory neurons-either prenatally (Ank3-/-:Emx1-Cre) or in adolescence (Ank3-/-:CaMKIIα-Cre) leads to convergent behavioral phenotypes in adulthood, including hyperactivity, reduced anxiety-like behavior, and decreased depression-like responses. Calcium imaging in cultured neurons and acute brain slices revealed that ankyrin-G loss reduces both spontaneous and evoked neuronal activity. Quantitative proteomic profiling of membrane-enriched cortical fractions uncovered widespread remodeling of the synaptic proteome, including upregulation of the kinase Taok2 and unexpected downregulation of myelin basic protein (Mbp), a structural component of oligodendrocyte-derived myelin. Importantly, chronic lithium treatment, known to reverse behavioral abnormalities in Ank3-deficient mice, also restored Mbp expression. Together, our findings identify ankyrin-G as a molecular bridge between excitatory neuronal activity, synaptic structure, and myelin-associated protein expression, revealing a pathway by which ANK3 variants may contribute to neuropsychiatric disease.

Animals

Genome-Wide Identification and Expression Pattern of the ANK Gene Family in Sorghum bicolor Under Salt Stress.

The Ankyrin-repeat proteins (ANKs) play a key role in plant development and in response to abiotic stress. This research identified family members of the ANK genes in Sorghum bicolor at the whole-genome level, analyzed their sequence characteristics, evolutionary relationships, and expression patterns, and provided a scientific basis for elucidating the functionality of SbANK genes and for salt-tolerant breeding. Using bioinformatics methods, this study conducted a comprehensive identification of the SbANK gene family, analyzing its physicochemical properties, domain composition, chromosomal distribution, colinearity relationships, promoter cis-acting elements, and conserved protein motifs. Transcriptomic data and qRT-PCR were used to detect changes in their expression under salt stress. A total of 186 ANK family members were identified in the Sorghum bicolor genome, classified into 13 subfamilies and unevenly distributed across 10 chromosomes. Intra-species colinearity analysis revealed 7 pairs of duplicated genes, while inter-species colinearity analysis showed that S. bicolor and Oryza sativa share 88 pairs of orthologs, far exceeding the number found in Arabidopsis thaliana (11 pairs). Promoter analysis indicated that SbANK genes are enriched with cis-acting elements associated with hormone responses (particularly MeJA elements, accounting for 51.7%) and stress responses (particularly anaerobic-inducible elements, accounting for 60.9%). Transcriptomic expression analysis revealed that SbANK genes exhibit distinct tissue specificity, with the ANK-IQ subfamily highly expressed in leaves and the ANK-M subfamily showing the most widespread response under salt stress. Expression levels of the 10 candidate genes showing the most significant responses to salt stress were analyzed using qRT-PCR. The results indicated that SbANK91, SbANK135, and SbANK136 were significantly upregulated under 200 mmol/L NaCl treatment. The SbANK family is distinguished by a large number of member genes and structural diversity, with the ANK-M subfamily being the primary group responding to salt stress. SbANK91, SbANK135, and SbANK136 are identified as putative candidate genes for salt stress responses.

Sorghum

Structure and Methyl-lysine Binding Selectivity of the HUSH Complex Subunit MPP8.

The Human Silencing Hub (HUSH) guards the genome from the pathogenic effects of retroelement expression. Composed of MPP8, TASOR, and Periphilin-1, HUSH recognizes actively transcribed retrotransposed sequences by the presence of long (>1.5-kb) nascent transcripts without introns. HUSH recruits effectors that alter chromatin structure, degrade transcripts, and deposit transcriptionally repressive epigenetic marks. Here, we report the crystal structure of the C-terminal domain (CTD) of MPP8 necessary for HUSH activity. The MPP8 CTD consists of five ankyrin repeats followed by a domain with structural homology to the PINIT domains of Siz/PIAS-family SUMO E3 ligases. AlphaFold3 modeling of the MPP8-TASOR complex predicts that a SPOC domain and a domain with a novel fold in TASOR form extended interaction interfaces with the MPP8 CTD. Point mutations at these interfaces resulted in loss of HUSH-dependent transcriptional repression in a cell-based reporter assay, validating the AlphaFold3 model. The MPP8 chromodomain, known to bind the repressive mark H3K9me3, bound with similar or higher affinity to sequences in the H3K9 methyltransferase subunits SETDB1, ATF7IP, G9a, and GLP. Hence, MPP8 promotes heterochromatinization by recruiting H3K9 methyltransferases. Our work identifies novel structural elements in MPP8 required for HUSH complex assembly and silencing, thereby fulfilling vital functions in controlling retrotransposons.

Humans

Genomic signatures of cold adaptation in a Himalayan drosophilid.

Drosophila nepalensis is a cold-adapted drosophilid endemic to the Himalayan region. Its ability to survive in harsh, cold conditions makes it a valuable Drosophila model for investigating how adaptation to thermal extremes may influence species persistence under future climate change. Here, we report the first de novo genome assembly of D. nepalensis, based on a hybrid sequencing strategy that combines Illumina short reads and Oxford Nanopore long reads. Illumina sequencing generated 49.88 million 150 bp paired-end reads (∼14.96 Gbp), while Nanopore sequencing produced 1.35 million long reads totaling ∼0.76 Gbp. The assembled genome spanned ∼178 Mb with an N50 of 83.6 kb and 98% BUSCO completeness, comparable to other well-annotated Drosophila genomes. Annotation identified 10,560 protein-coding genes, including transcription factor-rich and stress-related domains such as zinc fingers, WD40 repeats, and ankyrin motifs. Comparative orthology analysis across 6 Drosophila species identified 14,168 orthologous clusters, of which 9,173 were shared among all 6 species, indicating a conserved core genomic set across the sampled taxa. D. nepalensis showed 83 unique orthogroups and 50 singletons, suggesting some lineage-specific gene expansions associated with cold adaptation and endemicity, including families encoding caspase-family apoptotic regulators, chromatin remodeling proteins (HMGB/protamine-like), and SNARE-domain vesicle trafficking factors. Gene family evolution analysis revealed the highest expansions in the cold-tolerant Himalayan drosophilid, D. nepalensis, including significant expansions in serine protease, chaperone, and neurotransmitter transporter families, alongside dramatic contractions of core histone gene families, suggesting lineage-specific chromatin remodeling and ecological specialization.

Drosophila nepalensis

Selective targeting of TBXT with DARPins identifies regulatory networks and therapeutic vulnerabilities in chordoma.

The embryonic transcription factor TBXT (brachyury) drives chordoma, a spinal neoplasm without effective drug therapies. TBXT's regulatory network is poorly understood, and strategies to disrupt its activity for therapeutic purposes are lacking. We developed designed ankyrin repeat proteins that block TBXT-DNA binding (T-DARPins). In chordoma cells, T-DARPins reduced cell cycle progression, spheroid formation, and tumor growth in mice and induced signs of senescence and differentiation. Transcriptomic and proteomic analyses identified gene networks involved in cell cycle regulation, embryonic cell identity, and interferon response and revealed features of regulome components, such as susceptibility to pharmacologic inhibition and the fine-tuning of TBXT downstream effectors through IGFBP3. Finally, we found high interferon signaling in chordoma cell lines and patient tumors, which was promoted by TBXT and associated with sensitivity to JAK2 inhibitors. These findings demonstrate the potential of DARPins for probing nuclear proteins to understand the regulatory networks of transcription factor-driven cancers, including entry points for therapies that warrant testing in patients.

Humans

Coral color morphs exhibit distinct microbial and proteomic profiles linked to stress and immune mechanisms in a changing ocean.

BACKGROUND: Coral phenotypic plasticity facilitates acclimation and adaptation to environmental variability. Coral species often display a variety of color morphs, yet key biological and ecological implications of such phenotypic variation remain underexplored. Here, we present the first proteomic and untargeted lipidomic and metabolomic survey to explore the biological characteristics and potential ecological significance of different color morphs (pink and brown) of healthy Pocillopora verrucosa sampled along a latitudinal gradient. RESULTS: Our multi-omic approach elucidated distinct mechanisms associated with these dominant color morphs. We discovered bacterial indicators specific to each morph: putative pathogens such as Salmonella, Escherichia-Shigella, and carotenoid-producing Gemmatimonas were notably associated with the pink morph, whereas the brown morph was associated with potentially beneficial bacteria, such as Lysobacter, Acinetobacter, and Endozoicomonas. Despite these microbiome differences, the lipidome and metabolome of P. verrucosa were surprisingly homogeneous across colors and locations, suggesting similar metabolic performances during summer conditions. Key polar and apolar lipid classes, such as fatty acids, glycerophosphocholines, and retinoids, were prevalent. Notably, our proteomic analysis revealed morph-specific expressions, with pink morphs exhibiting enhanced levels of GFP-like proteins, Ankyrin, and the enzyme pullulanase, suggesting novel putative protective roles. In contrast, the brown morphs showed a higher abundance of heat shock proteins, indicating putative differential stress response capabilities. CONCLUSION: This comprehensive study provides the first proteomic survey of P. verrucosa and identifies key physiological pathways and trade-offs linked to color morphs, which can further contribute to enhancing our understanding of coral resilience in the face of climate change. SIGNIFICANCE STATEMENT: Understanding the phenotypic plasticity of corals is crucial for uncovering mechanisms of resilience in warming oceans, yet the biological significance of coral color morphs still needs to be explored. Using an innovative multi-omic approach (proteomics, lipidomics, and metabolomics), we provide the first comprehensive analysis of differences between pink and brown morphs of Pocillopora verrucosa. Our data reveal key taxa, potentially pathogenic or beneficial, associated with each morph, and suggest different strategies for each color morph to cope with heat stress, either expressing proteins involved in UV protection and heterotrophic activity or enhanced levels of heat stress resilience and DNA repair. These findings offer insights into the phenotypic plasticity of coral color morphs and their differential responses to climate change. Video Abstract.

Anthozoa

Expanding the genetic landscape of SLC4A1-linked hereditary spherocytosis: discovery of a novel TM9 variant using high-resolution genomic profiling analysis.

INTRODUCTION: Hereditary spherocytosis (HS) is the most common inherited red cell membranopathy caused by defects in erythrocyte membrane and cytoskeletal proteins, including ankyrin, spectrin, band 3, and protein 4.2. Among these, mutations in SLC4A1, which encodes the erythrocyte anion exchanger band 3 (AE1), account for approximately 20-30% of HS cases and it is associated with distal renal tubular acidosis (dRTA), reflecting phenotypic and functional heterogeneity. METHODS: In this study, seven unrelated Indian patients with clinically suspected HS were investigated using detailed hematological, biochemical, and clinical evaluations along with eosin-5'-maleimide (EMA) binding assays. Molecular analysis was performed using targeted next-generation sequencing (t-NGS) covering 81 genes associated with red cell disorders, and the identified SLC4A1 variants were validated by Sanger sequencing. The structural and functional consequences of the variants were assessed through in silico tools including DynaMut, PolyPhen-2, and SIFT. RESULTS: Seven SLC4A1 variants were identified, including six previously reported variants and one novel variant, p.Phe702Ser, detected in heterozygous or compound heterozygous states. These variants were distributed across both cytoplasmic and transmembrane domains of the band 3 protein. Most patients presented with mild to moderate HS characterized by anemia, jaundice, splenomegaly, reticulocytosis, and reduced EMA fluorescence. One patient harboring compound heterozygous variants (p.Arg490His and p.Ala858Asp) exhibited HS associated with dRTA, highlighting the functional diversity of SLC4A1 mutations. The novel p.Phe702Ser variant, located in the transmembrane domain TM9, was predicted to destabilize AE1 structure and potentially impair anion transport. DISCUSSION: Marked intrafamilial phenotypic variability was observed despite identical genotypes. These findings expand the mutational spectrum of SLC4A1-related HS in Indian patients.

SLC4A1

Genome-Wide Characterization of Calmodulin-Binding Transcription Activators Genes in Aegilops tauschii.

Calcium signaling plays a central role in plant adaptation to abiotic stresses and is primarily mediated by calmodulin and its associated transcription factors. Calmodulin-binding transcription activators (CAMTAs) regulate stress-responsive gene expression, but their characteristics and functions remain largely unexplored in Aegilops tauschii Coss., the D-genome progenitor of bread wheat. In this study, a genome-wide identification and characterization of the CAMTA gene family was performed, followed by phylogenetic, structural, conserved domain, promoter cis-element, and expression analyses under drought stress. Five AetCAMTA genes were identified and classified into three phylogenetic groups. All proteins contained conserved CG-1 DNA-binding, ankyrin repeat (ANK), and IQ calmodulin-binding domains and exhibited similar exon-intron organization. Promoter analysis revealed abundant hormone- and stress-responsive cis-elements, particularly abscisic acid-responsive element (ABRE) and drought-responsive MYB-binding site (MBS) motifs, suggesting their involvement in drought-responsive signaling. Quantitative RT-PCR showed genotype- and stress-dependent expression patterns, with the drought-tolerant ecotype (TN-01-1747) exhibiting higher expression of AetCAMTA1, AetCAMTA2, and AetCAMTA3 than the drought-sensitive ecotype (TN-01-1559) under moderate drought stress. These findings provide new insights into the evolutionary and functional characteristics of AetCAMTA genes and identify promising candidates for improving drought tolerance in wheat through molecular breeding and biotechnological approaches.

Gene Expression Regulation, Plant

Discovery of a potential novel pharmacogenomic biomarker on ANK3 gene for liafensine, a triple reuptake inhibitor for treatment-resistant depression.

Liafensine is a triple reuptake inhibitor targeting transporters for serotonin, norepinephrine, and dopamine for treatment-resistant depression (TRD). It did not exhibit efficacy in non-biomarker-selected TRD patients in two Phase 2b studies. We utilized the blood samples from the patients enrolled in these two studies and extracted genomic DNA to conduct a genome‑wide association study aiming to find a biomarker which can predict liafensine response. A single single-nucleotide polymorphism (SNP), rs12217173, at ANK3 gene was identified as strongly associated with treatment response to liafensine (p = 6.61 × 10-8) in the discovery set (n = 186) and was further confirmed in the replication sample set (n = 47, p = 0.05, combined p = 1.27 × 10-8). In addition, this SNP was not associated with the efficacy of the duloxetine or escitalopram, suggesting it is a liafensine-specific biomarker. This finding was subsequently confirmed in a prospective clinical study. Thus, this study represents a novel approach to translating precision medicine into psychiatric diseases.

Humans