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Redox Biology Apr 2024The function of SLC7A11 in the process of ferroptosis is well-established, as it regulates the synthesis of glutathione (GSH), thereby influencing tumor development...
The function of SLC7A11 in the process of ferroptosis is well-established, as it regulates the synthesis of glutathione (GSH), thereby influencing tumor development along with drug resistance in non-small cell lung cancer (NSCLC). However, the determinants governing SLC7A11's membrane trafficking and localization remain unknown. Our study identified SPTBN2 as a ferroptosis suppressor, enhancing NSCLC cells resistance to ferroptosis inducers. Mechanistically, SPTBN2, through its CH domain, interacted with SLC7A11 and connected it with the motor protein Arp1, thus facilitating the membrane localization of SLC7A11 - a prerequisite for its role as System Xc, which mediates cystine uptake and GSH synthesis. Consequently, SPTBN2 suppressed ferroptosis through preserving the functional activity of System Xc on the membrane. Moreover, Inhibiting SPTBN2 increased the sensitivity of NSCLC cells to cisplatin through ferroptosis induction, both in vitro and in vivo. Using Abrine as a potential SPTBN2 inhibitor, its efficacy in promoting ferroptosis and sensitizing NSCLC cells to cisplatin was validated. Collectively, SPTBN2 is a potential therapeutic target for addressing ferroptosis dysfunction and cisplatin resistance in NSCLC.
Topics: Humans; Amino Acid Transport System y+; Biological Transport; Carcinoma, Non-Small-Cell Lung; Cisplatin; Ferroptosis; Glutathione; Lung Neoplasms; Spectrin
PubMed: 38241838
DOI: 10.1016/j.redox.2024.103039 -
Nature Communications Dec 2023Force transmission at integrin-based adhesions is important for cell migration and mechanosensing. Talin is an essential focal adhesion (FA) protein that links F-actin...
Force transmission at integrin-based adhesions is important for cell migration and mechanosensing. Talin is an essential focal adhesion (FA) protein that links F-actin to integrins. F-actin constantly moves on FAs, yet how Talin simultaneously maintains the connection to F-actin and transmits forces to integrins remains unclear. Here we show a critical role of dynamic Talin unfolding in force transmission. Using single-molecule speckle microscopy, we found that the majority of Talin are bound only to either F-actin or the substrate, whereas 4.1% of Talin is linked to both structures via elastic transient clutch. By reconstituting Talin knockdown cells with Talin chimeric mutants, in which the Talin rod subdomains are replaced with the stretchable β-spectrin repeats, we show that the stretchable property is critical for force transmission. Simulations suggest that unfolding of the Talin rod subdomains increases in the linkage duration and work at FAs. This study elucidates a force transmission mechanism, in which stochastic molecular stretching bridges two cellular structures moving at different speeds.
Topics: Actins; Talin; Actin Cytoskeleton; Integrins; Focal Adhesions
PubMed: 38123541
DOI: 10.1038/s41467-023-44018-z -
Frontiers in Genetics 2023Hereditary spherocytosis (HS) is a congenital haemolytic anaemia attributed to dysregulation or abnormal quantities of erythrocyte membrane proteins. Currently, the...
Hereditary spherocytosis (HS) is a congenital haemolytic anaemia attributed to dysregulation or abnormal quantities of erythrocyte membrane proteins. Currently, the most common erythrocytic gene, spectrin β (), variants are located in exons and give rise to mRNA defects. However, the genetic characteristics and pathogenic mechanisms of intronic variants are not completely understood. This study aimed to analyse a rare intronic inversion variant in the gene associated with HS, and explore the impact of the variant on mRNA splicing. The clinical manifestations of the patient were summarised and analysed for spherocytosis phenotype diagnosis. The pathogenic variant was identified in the proband using targeted next-generation and Sanger sequencing. RNA sequencing was performed to analyse whether gene splicing and expression were affected. Targeted next-generation sequencing identified a novel disease-associated intronic inversion variant of the gene in the proband. The inversion variant was located between intron 19 and 20, and contained the entire exon 20 and partial sequences of adjacent introns. Sanger sequencing confirmed that the intronic inversion variant only appeared in the genome of the proband, not in his parents. RNA sequencing revealed that the variant could result in the skipping of exon 20 and reduced expression of mRNA. This study identifies a rare intronic inversion variant in the gene associated with hereditary spherocytosis. The pathogenic variant can lead to exon 20 skipping and decreased gene expression. This finding has not been previously reported in any literature. This study can expand the intronic variant spectrum of the gene, deepen our understanding of HS pathogenesis, and contribute to the genetic diagnosis and clinical management of patients.
PubMed: 38111681
DOI: 10.3389/fgene.2023.1309040 -
Nature Communications Dec 2023The axon initial segment (AIS) is a specialized neuronal compartment required for action potential generation and neuronal polarity. However, understanding the...
The axon initial segment (AIS) is a specialized neuronal compartment required for action potential generation and neuronal polarity. However, understanding the mechanisms regulating AIS structure and function has been hindered by an incomplete knowledge of its molecular composition. Here, using immuno-proximity biotinylation we further define the AIS proteome and its dynamic changes during neuronal maturation. Among the many AIS proteins identified, we show that SCRIB is highly enriched in the AIS both in vitro and in vivo, and exhibits a periodic architecture like the axonal spectrin-based cytoskeleton. We find that ankyrinG interacts with and recruits SCRIB to the AIS. However, loss of SCRIB has no effect on ankyrinG. This powerful and flexible approach further defines the AIS proteome and provides a rich resource to elucidate the mechanisms regulating AIS structure and function.
Topics: Axon Initial Segment; Proteome; Biotinylation; Axons; Neurons
PubMed: 38081810
DOI: 10.1038/s41467-023-44015-2 -
Heliyon Dec 2023Spectrin breakdown products 145 kDa (SBDP145) and neurofilament heavy chain (Nf-H) have been identified as potential biomarkers of neuronal injury. However, their...
OBJECTIVES
Spectrin breakdown products 145 kDa (SBDP145) and neurofilament heavy chain (Nf-H) have been identified as potential biomarkers of neuronal injury. However, their ability to predict hypoxic-ischemic brain injury following cardiac arrest in humans is not well understood. This study aimed to investigate whether SBDP145 and Nf-H could be used as biomarkers to predict neurological outcomes after cardiac arrest.
METHODS
This prospective study was conducted at two academic hospitals and included adults who survived after cardiac arrest. Blood samples were collected at 0, 24, and 48 h after the return of spontaneous circulation, and biomarker analyses were performed to measure SBDP145 and Nf-H. Poor neurological outcome was defined as a modified Rankin Score of 4-6, and diagnostic performance was determined by receiver-operating characteristics analysis.
RESULTS
A total of 56 patients were included in this study. There were no significant differences in levels of SBDP145 or Nf-H between the poor and good outcome groups at any time point. Areas under the receiver-operating characteristics curve of SBDP145 and Nf-H were small, ranging from 0.51 to 0.7. At 0, 24, and 48 h, SBDP145 showed very low sensitivity (18.61 %, 13.89 %, and 13.79 %, respectively) and accuracy (33.93 %, 36.74 %, and 39.02 %, respectively) at a cut-off value for 100 % specificity. Nf-H also showed very low sensitivity (9.30 %, 16.67 %, and 0 %, respectively) and accuracy (29.09 %, 36.74 %, and 30.95 %, respectively).
CONCLUSIONS
SBDP145 and Nf-H were found to be poor predictors of poor neurological outcomes six months after cardiac arrest.
PubMed: 38076158
DOI: 10.1016/j.heliyon.2023.e22582 -
International Journal of Molecular... Nov 2023Congenital defects of the erythrocyte membrane are common in northern Europe and all over the world. The resulting diseases, for example, hereditary spherocytosis (HS),...
Congenital defects of the erythrocyte membrane are common in northern Europe and all over the world. The resulting diseases, for example, hereditary spherocytosis (HS), are often underdiagnosed, partly due to their sometimes mild and asymptomatic courses. In addition to a broad clinical spectrum, this is also due to the occasionally complex diagnostics that are not available to every patient. To test whether next-generation sequencing (NGS) could replace time-consuming spherocytosis-specific functional tests, 22 consecutive patients with suspected red cell membranopathy underwent functional blood tests. We were able to identify the causative genetic defect in all patients with suspected HS who underwent genetic testing ( = 17). The sensitivity of the NGS approach, which tests five genes ( (gene product: ankyrin1), (erythrocyte membrane protein band4.2), (band3), (α-spectrin), and (β-spectrin)), was 100% (95% confidence interval: 81.5-100.0%). The major advantage of genetic testing in the paediatric setting is the small amount of blood required (<200 µL), and compared to functional assays, sample stability is not an issue. The combination of medical history, basic laboratory parameters, and an NGS panel with five genes is sufficient for diagnosis in most cases. Only in rare cases, a more comprehensive functional screening is required.
Topics: Humans; Child; Ankyrins; Mutation; Spherocytosis, Hereditary; Spectrin; Cytoskeletal Proteins; High-Throughput Nucleotide Sequencing
PubMed: 38069343
DOI: 10.3390/ijms242317021 -
International Journal of Molecular... Nov 2023Seminoma is the most common testicular cancer. Pituitary tumor-transforming gene 1 (PTTG1) is a securin showing oncogenic activity in several tumors. We previously...
Seminoma is the most common testicular cancer. Pituitary tumor-transforming gene 1 (PTTG1) is a securin showing oncogenic activity in several tumors. We previously demonstrated that nuclear PTTG1 promotes seminoma tumor invasion through its transcriptional activity on matrix metalloproteinase 2 () and E-cadherin (). We wondered if specific interactors could affect its subcellular distribution. To this aim, we investigated the PTTG1 interactome in seminoma cell lines showing different PTTG1 nuclear levels correlated with invasive properties. A proteomic approach upon PTTG1 immunoprecipitation uncovered new specific securin interactors. Western blot, confocal microscopy, cytoplasmic/nuclear fractionation, sphere-forming assay, and Atlas database interrogation were performed to validate the proteomic results and to investigate the interplay between PTTG1 and newly uncovered partners. We observed that spectrin beta-chain (SPTBN1) and PTTG1 were cofactors, with SPTBN1 anchoring the securin in the cytoplasm. SPTBN1 downregulation determined PTTG1 nuclear translocation, promoting its invasive capability. Moreover, a PTTG1 deletion mutant lacking SPTBN1 binding was strongly localized in the nucleus. The Atlas database revealed that seminomas that contained higher nuclear PTTG1 levels showed significantly lower SPTBN1 levels in comparison to non-seminomas. In human seminoma specimens, we found a strong PTTG1/SPTBN1 colocalization that decreases in areas with nuclear PTTG1 distribution. Overall, these results suggest that SPTBN1, along with PTTG1, is a potential prognostic factor useful in the clinical management of seminoma.
Topics: Humans; Male; Cell Line, Tumor; Cytoplasm; Gene Expression Regulation, Neoplastic; Matrix Metalloproteinase 2; Proteomics; Securin; Seminoma; Spectrin; Testicular Neoplasms
PubMed: 38069214
DOI: 10.3390/ijms242316891 -
BioRxiv : the Preprint Server For... Nov 2023Facioscapulohumeral muscular dystrophy (FSHD) disease progression is associated with muscle inflammation, although its role in FSHD muscle pathology is unknown.
BACKGROUND
Facioscapulohumeral muscular dystrophy (FSHD) disease progression is associated with muscle inflammation, although its role in FSHD muscle pathology is unknown.
METHODS
We have developed a novel humanized mouse strain, NSG-SGM3-W41, that supports the co- engraftment of human hematopoietic stem cells (HSCs) and muscle myoblasts as an experimental model to investigate the role of innate immunity in FSHD muscle pathology.
RESULTS
The NSG-SGM3-W41 mouse supports the selective expansion of human innate immune cell lineages following engraftment of human HSCs and the co-engraftment and differentiation of patient-derived FSHD or control muscle myoblasts. Immunohistological and NanoString RNA expression assays establish that muscle xenografts from three FSHD subjects were immunogenic compared to those from unaffected first-degree relatives. FSHD muscle xenografts preferentially accumulated human macrophages and B cells and expressed early complement genes of the classical and alternative pathways including complement factor C3 protein, which is a mediator of early complement function through opsonization to mark damaged cells for macrophage engulfment. FSHD muscle xenografts also underwent immune donor dependent muscle turnover as assayed by human spectrin β1 immunostaining of muscle fibers and by NanoString RNA expression assays of muscle differentiation genes.
CONCLUSIONS
The NSG-SGM3-W41 mouse provides an experimental model to investigate the role of innate immunity and complement in FSHD muscle pathology and to develop FSHD therapeutics targeting DUX4 and the innate immunity inflammatory responses.
PubMed: 38014123
DOI: 10.1101/2023.11.17.567590 -
Brain Sciences Nov 2023Diffuse axonal injury (DAI) is a significant feature of traumatic brain injury (TBI) across all injury severities and is driven by the primary mechanical insult and... (Review)
Review
Diffuse axonal injury (DAI) is a significant feature of traumatic brain injury (TBI) across all injury severities and is driven by the primary mechanical insult and secondary biochemical injury phases. Axons comprise an outer cell membrane, the axolemma which is anchored to the cytoskeletal network with spectrin tetramers and actin rings. Neurofilaments act as space-filling structural polymers that surround the central core of microtubules, which facilitate axonal transport. TBI has differential effects on these cytoskeletal components, with axons in the same white matter tract showing a range of different cytoskeletal and axolemma alterations with different patterns of temporal evolution. These require different antibodies for detection in post-mortem tissue. Here, a comprehensive discussion of the evolution of axonal injury within different cytoskeletal elements is provided, alongside the most appropriate methods of detection and their temporal profiles. Accumulation of amyloid precursor protein (APP) as a result of disruption of axonal transport due to microtubule failure remains the most sensitive marker of axonal injury, both acutely and chronically. However, a subset of injured axons demonstrate different pathology, which cannot be detected via APP immunoreactivity, including degradation of spectrin and alterations in neurofilaments. Furthermore, recent work has highlighted the node of Ranvier and the axon initial segment as particularly vulnerable sites to axonal injury, with loss of sodium channels persisting beyond the acute phase post-injury in axons without APP pathology. Given the heterogenous response of axons to TBI, further characterization is required in the chronic phase to understand how axonal injury evolves temporally, which may help inform pharmacological interventions.
PubMed: 38002566
DOI: 10.3390/brainsci13111607