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International Journal of Biological... 2021βII spectrin, the most common isoform of non-erythrocyte spectrin, is a cytoskeleton protein present in all nucleated cells. Interestingly, βII spectrin is essential... (Review)
Review
βII spectrin, the most common isoform of non-erythrocyte spectrin, is a cytoskeleton protein present in all nucleated cells. Interestingly, βII spectrin is essential for the development of various organs such as nerve, epithelium, inner ear, liver and heart. The functions of βII spectrin include not only establishing and maintaining the cell structure but also regulating a variety of cellular functions, such as cell apoptosis, cell adhesion, cell spreading and cell cycle regulation. Notably, βII spectrin dysfunction is associated with embryonic lethality and the DNA damage response. More recently, the detection of altered βII spectrin expression in tumors indicated that βII spectrin might be involved in the development and progression of cancer. Its mutations and disorders could result in developmental disabilities and various diseases. The versatile roles of βII spectrin in disease have been examined in an increasing number of studies; nonetheless, the exact mechanisms of βII spectrin are still poorly understood. Thus, we summarize the structural features and biological roles of βII spectrin and discuss its molecular mechanisms and functions in development, homeostasis, regeneration and differentiation. This review highlight the potential effects of βII spectrin dysfunction in cancer and other diseases, outstanding questions for the future investigation of therapeutic targets. The investigation of the regulatory mechanism of βII spectrin signal inactivation and recovery may bring hope for future therapy of related diseases.
Topics: Animals; Cell Adhesion; Cell Cycle; Disease; Genomic Instability; Humans; Molecular Targeted Therapy; Neoplasms; Spectrin
PubMed: 33390831
DOI: 10.7150/ijbs.52375 -
Science Translational Medicine Dec 2021The prevalence of nonalcoholic steatohepatitis (NASH) and liver cancer is increasing. De novo lipogenesis and fibrosis contribute to disease progression and cancerous...
The prevalence of nonalcoholic steatohepatitis (NASH) and liver cancer is increasing. De novo lipogenesis and fibrosis contribute to disease progression and cancerous transformation. Here, we found that β2-spectrin (SPTBN1) promotes sterol regulatory element (SRE)–binding protein (SREBP)–stimulated lipogenesis and development of liver cancer in mice fed a high-fat diet (HFD) or a western diet (WD). Either hepatocyte-specific knockout of SPTBN1 or siRNA-mediated therapy protected mice from HFD/WD-induced obesity and fibrosis, lipid accumulation, and tissue damage in the liver. Biochemical analysis suggested that HFD/WD induces SPTBN1 and SREBP1 cleavage by CASPASE-3 and that the cleaved products interact to promote expression of genes with sterol response elements. Analysis of human NASH tissue revealed increased and expression. Thus, our data indicate that SPTBN1 represents a potential target for therapeutic intervention in NASH and liver cancer.
Topics: Animals; Diet, High-Fat; Liver; Mice; Mice, Inbred C57BL; Neoplasms; Non-alcoholic Fatty Liver Disease; Spectrin
PubMed: 34910547
DOI: 10.1126/scitranslmed.abk2267 -
Neuropathology and Applied Neurobiology Oct 2021MICU1 encodes the gatekeeper of the mitochondrial Ca uniporter, MICU1 and biallelic loss-of-function mutations cause a complex, neuromuscular disorder in children....
AIMS
MICU1 encodes the gatekeeper of the mitochondrial Ca uniporter, MICU1 and biallelic loss-of-function mutations cause a complex, neuromuscular disorder in children. Although the role of the protein is well understood, the precise molecular pathophysiology leading to this neuropaediatric phenotype has not been fully elucidated. Here we aimed to obtain novel insights into MICU1 pathophysiology.
METHODS
Molecular genetic studies along with proteomic profiling, electron-, light- and Coherent anti-Stokes Raman scattering microscopy and immuno-based studies of protein abundances and Ca transport studies were employed to examine the pathophysiology of MICU1 deficiency in humans.
RESULTS
We describe two patients carrying MICU1 mutations, two nonsense (c.52C>T; p.(Arg18*) and c.553C>T; p.(Arg185*)) and an intragenic exon 2-deletion presenting with ataxia, developmental delay and early onset myopathy, clinodactyly, attention deficits, insomnia and impaired cognitive pain perception. Muscle biopsies revealed signs of dystrophy and neurogenic atrophy, severe mitochondrial perturbations, altered Golgi structure, vacuoles and altered lipid homeostasis. Comparative mitochondrial Ca transport and proteomic studies on lymphoblastoid cells revealed that the [Ca ] threshold and the cooperative activation of mitochondrial Ca uptake were lost in MICU1-deficient cells and that 39 proteins were altered in abundance. Several of those proteins are linked to mitochondrial dysfunction and/or perturbed Ca homeostasis, also impacting on regular cytoskeleton (affecting Spectrin) and Golgi architecture, as well as cellular survival mechanisms.
CONCLUSIONS
Our findings (i) link dysregulation of mitochondrial Ca uptake with muscle pathology (including perturbed lipid homeostasis and ER-Golgi morphology), (ii) support the concept of a functional interplay of ER-Golgi and mitochondria in lipid homeostasis and (iii) reveal the vulnerability of the cellular proteome as part of the MICU1-related pathophysiology.
Topics: Calcium; Calcium-Binding Proteins; Cation Transport Proteins; Humans; Mitochondria; Mitochondrial Membrane Transport Proteins; Muscular Diseases; Proteomics
PubMed: 33428302
DOI: 10.1111/nan.12694 -
BMC Genomics Jun 2023Hereditary spherocytosis (HS) is a common inherited hemolytic anemia, caused by mutations in five genes that encode erythrocyte membrane skeleton proteins. The red blood...
BACKGROUND
Hereditary spherocytosis (HS) is a common inherited hemolytic anemia, caused by mutations in five genes that encode erythrocyte membrane skeleton proteins. The red blood cell (RBC) lifespan could directly reflect the degree of hemolysis. In the present cohort of 23 patients with HS, we performed next-generation sequencing (NGS) and Levitt's carbon monoxide (CO) breath test to investigate the potential genotype-degree of hemolysis correlation.
RESULTS
In the present cohort, we identified 8 ANK1,9 SPTB,5 SLC4A1 and 1 SPTA1 mutations in 23 patients with HS, and the median RBC lifespan was 14(8-48) days. The median RBC lifespan of patients with ANK1, SPTB and SLC4A1 mutations was 13 (8-23), 13 (8-48) and 14 (12-39) days, respectively, with no statistically significant difference (P = 0.618). The median RBC lifespan of patients with missense, splice and nonsense/insertion/deletion mutations was 16.5 (8-48), 14 (11-40) and 13 (8-20) days, respectively, with no significant difference (P = 0.514). Similarly, we found no significant difference in the RBC lifespan of patients with mutations located in the spectrin-binding domain and the nonspectrin-binding domain [14 (8-18) vs. 12.5 (8-48) days, P = 0.959]. In terms of the composition of mutated genes, 25% of patients with mild hemolysis carried ANK1 or SPTA1 mutations, while 75% of patients with mild hemolysis carried SPTB or SLC4A1 mutations. In contrast, 46.7% of patients with severe hemolysis had ANK1 or SPTA1 mutations and 53.3% of patients with severe hemolysis had SPTB or SLC4A1 mutations. However, there was no statistically significant difference in the distribution of mutated genes between the two groups (P = 0.400).
CONCLUSION
The present study is the first to investigate the potential association between genotype and degree of hemolysis in HS. The present findings indicated that there is no significant correlation between genotype and degree of hemolysis in HS.
Topics: Humans; Hemolysis; Ankyrins; Spectrin; Spherocytosis, Hereditary; Cytoskeletal Proteins; Membrane Proteins; Mutation; Genotype
PubMed: 37280519
DOI: 10.1186/s12864-023-09364-8 -
Biochemical Society Transactions Jun 2023Nesprins (nuclear envelope spectrin repeat proteins) are multi-isomeric scaffolding proteins. Giant nesprin-1 and -2 localise to the outer nuclear membrane, interact... (Review)
Review
Nesprins (nuclear envelope spectrin repeat proteins) are multi-isomeric scaffolding proteins. Giant nesprin-1 and -2 localise to the outer nuclear membrane, interact with SUN (Sad1p/UNC-84) domain-containing proteins at the inner nuclear membrane to form the LInker of Nucleoskeleton and Cytoskeleton (LINC) complex, which, in association with lamin A/C and emerin, mechanically couples the nucleus to the cytoskeleton. Despite ubiquitous expression of nesprin giant isoforms, pathogenic mutations in nesprin-1 and -2 are associated with tissue-specific disorders, particularly related to striated muscle such as dilated cardiomyopathy and Emery-Dreifuss muscular dystrophy. Recent evidence suggests this muscle-specificity might be attributable in part, to the small muscle specific isoform, nesprin-1α2, which has a novel role in striated muscle function. Our current understanding of muscle-specific functions of nesprin-1 and its isoforms will be summarised in this review to provide insight into potential pathological mechanisms of nesprin-related muscle disease and may inform potential targets of therapeutic modulation.
Topics: Humans; Cell Nucleus; Mechanotransduction, Cellular; Muscle, Skeletal; Muscular Diseases; Nerve Tissue Proteins; Nuclear Envelope; Protein Isoforms; Animals
PubMed: 37171063
DOI: 10.1042/BST20221541 -
Molecular and Cellular Biology Aug 2020Fodrin and its erythroid cell-specific isoform spectrin are actin-associated fibrous proteins that play crucial roles in the maintenance of structural integrity in... (Review)
Review
Fodrin and its erythroid cell-specific isoform spectrin are actin-associated fibrous proteins that play crucial roles in the maintenance of structural integrity in mammalian cells, which is necessary for proper cell function. Normal cell morphology is altered in diseases such as various cancers and certain neuronal disorders. Fodrin and spectrin are two-chain (αβ) molecules that are encoded by paralogous genes and share many features but also demonstrate certain differences. Fodrin (in humans, typically a heterodimer of the products of the SPTAN1 and SPTBN1 genes) is expressed in nearly all cell types and is especially abundant in neuronal tissues, whereas spectrin (in humans, a heterodimer of the products of the SPTA1 and SPTB1 genes) is expressed almost exclusively in erythrocytes. To fulfill a role in such a variety of different cell types, it was anticipated that fodrin would need to be a more versatile scaffold than spectrin. Indeed, as summarized here, domains unique to fodrin and its regulation by Ca, calmodulin, and a variety of posttranslational modifications (PTMs) endow fodrin with additional specific functions. However, how fodrin structural variations and misregulated PTMs may contribute to the etiology of various cancers and neurodegenerative diseases needs to be further investigated.
Topics: Actins; Animals; Calcium; Calmodulin; Carrier Proteins; Erythroid Cells; Humans; Microfilament Proteins; Neurons; Spectrin; Structure-Activity Relationship
PubMed: 32601107
DOI: 10.1128/MCB.00133-20 -
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 -
Channels (Austin, Tex.) Dec 2022The ankyrin proteins (Ankyrin-R, Ankyrin-B, and Ankyrin-G) are a family of scaffolding, or membrane adaptor proteins necessary for the regulation and targeting of... (Review)
Review
The ankyrin proteins (Ankyrin-R, Ankyrin-B, and Ankyrin-G) are a family of scaffolding, or membrane adaptor proteins necessary for the regulation and targeting of several types of ion channels and membrane transporters throughout the body. These include voltage-gated sodium, potassium, and calcium channels in the nervous system, heart, lungs, and muscle. At these sites, ankyrins recruit ion channels, and other membrane proteins, to specific subcellular domains, which are then stabilized through ankyrin's interaction with the submembranous spectrin-based cytoskeleton. Several recent studies have expanded our understanding of both ankyrin expression and their ion channel binding partners. This review provides an updated overview of ankyrin proteins and their known channel and transporter interactions. We further discuss several potential avenues of future research that would expand our understanding of these important organizational proteins.
Topics: Ankyrins; Cytoskeleton; Ion Channels; Membrane Proteins; Spectrin
PubMed: 36082411
DOI: 10.1080/19336950.2022.2120467 -
Experimental Biology and Medicine... Nov 2019Spectrins are proteins that are responsible for many aspects of cell function and adaptation to changing environments. Primarily the spectrin-based membrane skeleton... (Review)
Review
UNLABELLED
Spectrins are proteins that are responsible for many aspects of cell function and adaptation to changing environments. Primarily the spectrin-based membrane skeleton maintains cell membrane integrity and its mechanical properties, together with the cytoskeletal network a support cell shape. The occurrence of a variety of spectrin isoforms in diverse cellular environments indicates that it is a multifunctional protein involved in numerous physiological pathways. Participation of spectrin in cell–cell and cell–extracellular matrix adhesion and formation of dynamic plasma membrane protrusions and associated signaling events is a subject of interest for researchers in the fields of cell biology and molecular medicine. In this mini-review, we focus on data concerning the role of spectrins in cell surface activities such as adhesion, cell–cell contact, and invadosome formation. We discuss data on different adhesion proteins that directly or indirectly interact with spectrin repeats. New findings support the involvement of spectrin in cell adhesion and spreading, formation of lamellipodia, and also the participation in morphogenetic processes, such as eye development, oogenesis, and angiogenesis. Here, we review the role of spectrin in cell adhesion and cell–cell contact.
IMPACT STATEMENT
This article reviews properties of spectrins as a group of proteins involved in cell surface activities such as, adhesion and cell–cell contact, and their contribution to morphogenesis. We show a new area of research and discuss the involvement of spectrin in regulation of cell–cell contact leading to immunological synapse formation and in shaping synapse architecture during myoblast fusion. Data indicate involvement of spectrins in adhesion and cell–cell or cell–extracellular matrix interactions and therefore in signaling pathways. There is evidence of spectrin’s contribution to the processes of morphogenesis which are connected to its interactions with adhesion molecules, membrane proteins (and perhaps lipids), and actin. Our aim was to highlight the essential role of spectrin in cell–cell contact and cell adhesion.
Topics: Animals; Cell Adhesion; Cell Communication; Humans; Morphogenesis; Spectrin
PubMed: 31226892
DOI: 10.1177/1535370219859003 -
Journal of Biomolecular Structure &... 2023Cytoskeletal drugs having enormous therapeutic potential act on the cytoskeletal components like actin, tubulin either by promoting polymerization or destabilizing the...
Cytoskeletal drugs having enormous therapeutic potential act on the cytoskeletal components like actin, tubulin either by promoting polymerization or destabilizing the same. Here we present the interaction of the popular cytoskeletal drugs such as taxol, latrunculin and cytochalasin with spectrin, a huge protein with multi domains that forms the cytoskeletal network. Particularly, the actin binding domain of spectrin regulates the dynamics of the actin cytoskeleton. We followed the binding of these drugs to its actin binding domain and intact spectrin as well. These drugs bind with moderate affinity (K ∼ 10 M) and the interaction with actin binding domain is entropy driven and hydrophobic in nature as determined by Van't Hoff plot. The docking studies and molecular dynamics simulations further corroborate the experimental findings. Particularly the higher binding constants in the case of latrunculin and cytochalasin to the actin binding domain of spectrin suggest the binding sites are presumably located in its actin binding domain.Communicated by Ramaswamy H. Sarma.
PubMed: 35994328
DOI: 10.1080/07391102.2022.2109063