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1.
Medicine (Baltimore) ; 100(35): e27162, 2021 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-34477172

RESUMO

ABSTRACT: Cancer-associated fibroblasts (CAFs) have been attracting attention in recent years, but their nature has not been fully elucidated. Although CAFs have been recognized as an important therapeutic target, therapeutic agents have not been developed to date. CAFs are characterized by their high migration rate and involvement in epithelial-to-mesenchymal transition with some displaying a dendritic morphology that is reminiscent of fascin expression.The present study was designed to immunohistochemically investigate fascin expression in lung adenocarcinoma including CAFs and compare the results with existing CAF markers.We immunohistochemically investigated fascin expression in not only cancer tissue but also CAFs from 26 autopsy cases of lung adenocarcinoma. Immunohistochemistry of α-smooth muscle actin and fibroblast activation protein was also performed.Fascin-positive staining in CAFs was observed in all cases, with a strong correlation observed with existing CAF markers α-smooth muscle actin and fibroblast activation protein (P < .001). In addition, the proportion of tumor cells showing fascin-positive staining was found to correlate with its expression in CAFs (P < .05).We propose that CAFs express fascin, and that fascin may mediate crosstalk between cancer tissue and CAFs. Fascin might be a novel therapeutic target for treatments that target the cancer stroma.


Assuntos
Adenocarcinoma/metabolismo , Fibroblastos Associados a Câncer/metabolismo , Proteínas de Transporte/metabolismo , Neoplasias Pulmonares/metabolismo , Proteínas dos Microfilamentos/metabolismo , Actinas/metabolismo , Adenocarcinoma/patologia , Idoso , Idoso de 80 Anos ou mais , Endopeptidases/metabolismo , Feminino , Humanos , Pulmão/patologia , Neoplasias Pulmonares/patologia , Masculino , Proteínas de Membrana/metabolismo , Pessoa de Meia-Idade
2.
Nat Commun ; 12(1): 5240, 2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-34475390

RESUMO

ß-actin is a crucial component of several chromatin remodeling complexes that control chromatin structure and accessibility. The mammalian Brahma-associated factor (BAF) is one such complex that plays essential roles in development and differentiation by regulating the chromatin state of critical genes and opposing the repressive activity of polycomb repressive complexes (PRCs). While previous work has shown that ß-actin loss can lead to extensive changes in gene expression and heterochromatin organization, it is not known if changes in ß-actin levels can directly influence chromatin remodeling activities of BAF and polycomb proteins. Here we conduct a comprehensive genomic analysis of ß-actin knockout mouse embryonic fibroblasts (MEFs) using ATAC-Seq, HiC-seq, RNA-Seq and ChIP-Seq of various epigenetic marks. We demonstrate that ß-actin levels can induce changes in chromatin structure by affecting the complex interplay between chromatin remodelers such as BAF/BRG1 and EZH2. Our results show that changes in ß-actin levels and associated chromatin remodeling activities can not only impact local chromatin accessibility but also induce reversible changes in 3D genome architecture. Our findings reveal that ß-actin-dependent chromatin remodeling plays a role in shaping the chromatin landscape and influences the regulation of genes involved in development and differentiation.


Assuntos
Actinas/metabolismo , Montagem e Desmontagem da Cromatina/fisiologia , Actinas/genética , Animais , Cromatina/metabolismo , DNA Helicases/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Epigênese Genética , Fibroblastos , Dosagem de Genes , Técnicas de Inativação de Genes , Histonas/metabolismo , Camundongos , Proteínas Nucleares/metabolismo , Proteínas do Grupo Polycomb/metabolismo , Ligação Proteica , Fatores de Transcrição/metabolismo
3.
Nat Commun ; 12(1): 4969, 2021 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-34404787

RESUMO

Multimeric cytoskeletal protein complexes orchestrate normal cellular function. However, protein-complex distributions in stressed, heterogeneous cell populations remain unknown. Cell staining and proximity-based methods have limited selectivity and/or sensitivity for endogenous multimeric protein-complex quantification from single cells. We introduce micro-arrayed, differential detergent fractionation to simultaneously detect protein complexes in hundreds of individual cells. Fractionation occurs by 60 s size-exclusion electrophoresis with protein complex-stabilizing buffer that minimizes depolymerization. Proteins are measured with a ~5-hour immunoassay. Co-detection of cytoskeletal protein complexes in U2OS cells treated with filamentous actin (F-actin) destabilizing Latrunculin A detects a unique subpopulation (~2%) exhibiting downregulated F-actin, but upregulated microtubules. Thus, some cells may upregulate other cytoskeletal complexes to counteract the stress of Latrunculin A treatment. We also sought to understand the effect of non-chemical stress on cellular heterogeneity of F-actin. We find heat shock may dysregulate filamentous and globular actin correlation. In this work, our assay overcomes selectivity limitations to biochemically quantify single-cell protein complexes perturbed with diverse stimuli.


Assuntos
Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Citoesqueleto/metabolismo , Heterogeneidade Genética , Actinas/genética , Actinas/metabolismo , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Diferenciação Celular , Linhagem Celular , Resposta ao Choque Térmico , Humanos , Microtúbulos/metabolismo , Modelos Biológicos , Análise de Célula Única/métodos , Tiazolidinas/farmacologia
4.
J Cell Sci ; 134(2)2021 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-34432031

RESUMO

Cell-cell junction formation requires actin cytoskeletal remodeling. Here, we show that PLEKHG4B, a Rho-guanine nucleotide exchange factor (Rho-GEF), plays a crucial role in epithelial cell-cell junction formation. Knockdown of PLEKHG4B decreased Cdc42 activity and tended to increase RhoA activity in A549 cells. A549 monolayer cells showed 'closed junctions' with closely packed actin bundles along the cell-cell contacts, but PLEKHG4B knockdown suppressed closed junction formation, and PLEKHG4B-knockdown cells exhibited 'open junctions' with split actin bundles located away from the cell-cell boundary. In Ca2+-switch assays, PLEKHG4B knockdown delayed the conversion of open junctions to closed junctions and ß-catenin accumulation at cell-cell junctions. Furthermore, PLEKHG4B knockdown abrogated the reduction in myosin activity normally seen in the later stage of junction formation. The aberrant myosin activation and impairments in closed junction formation in PLEKHG4B-knockdown cells were reverted by ROCK inhibition or LARG/PDZ-RhoGEF knockdown. These results suggest that PLEKHG4B enables actin remodeling during epithelial cell-cell junction maturation, probably by reducing myosin activity in the later stage of junction formation, through suppressing LARG/PDZ-RhoGEF and RhoA-ROCK pathway activities. We also showed that annexin A2 participates in PLEKHG4B localization to cell-cell junctions. This article has an associated First Person interview with the first author of the paper.


Assuntos
Actinas , Junções Intercelulares , Células A549 , Actinas/genética , Actinas/metabolismo , Citoesqueleto/metabolismo , Células Epiteliais/metabolismo , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Humanos , Junções Intercelulares/metabolismo , Fatores de Troca de Nucleotídeo Guanina Rho/genética , Proteína rhoA de Ligação ao GTP/genética , Proteína rhoA de Ligação ao GTP/metabolismo
5.
Int J Mol Sci ; 22(15)2021 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-34360602

RESUMO

The primary function of the endothelial cells (EC) lining the inner surface of all vessels is to regulate permeability of vascular walls and to control exchange between circulating blood and tissue fluids of organs. The EC actin cytoskeleton plays a crucial role in maintaining endothelial barrier function. Actin cytoskeleton reorganization result in EC contraction and provides a structural basis for the increase in vascular permeability, which is typical for many diseases. Actin cytoskeleton in non-muscle cells presented two actin isoforms: non-muscle ß-cytoplasmic and γ-cytoplasmic actins (ß-actins and γ-actins), which are encoded by ACTB and ACTG1 genes, respectively. They are ubiquitously expressed in the different cells in vivo and in vitro and the ß/γ-actin ratio depends on the cell type. Both cytoplasmic actins are essential for cell survival, but they perform various functions in the interphase and cell division and play different roles in neoplastic transformation. In this review, we briefly summarize the research results of recent years and consider the features of the cytoplasmic actins: The spatial organization in close connection with their functional activity in different cell types by focusing on endothelial cells.


Assuntos
Actinas/metabolismo , Citoplasma/metabolismo , Células Endoteliais/fisiologia , Animais , Células Endoteliais/citologia , Humanos
6.
Mol Med Rep ; 24(4)2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34328202

RESUMO

A number of drugs and other triggers can cause acute liver injury (ALI) in clinical practice. Therefore, identifying a safe drug for the prevention of liver injury is important. The aim of the present study was to investigate the potential preventive effect and regulatory mechanism of urantide on carbon tetrachloride (CCl4)­induced ALI by investigating the expression of components of the MAPK signalling pathway and the urotensin II (UII)/urotensin receptor (UT) system. Liver oedema and severe fatty degeneration of the cytoplasm were observed in ALI model rats, and the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were found to be significantly increased. Compared with those in the ALI model group, ALT and AST levels and the liver index did not significantly increase in each group given the preventive administration of urantide, and the liver tissue morphology was correspondingly protected. Moreover, the gene and protein expression levels of UII, G protein­coupled receptor (GPR14) and the oxidative stress­sensitive cytokines, α­smooth muscle actin and osteopontin were decreased, indicating that the protein translation process was effectively maintained. However, the expression levels of MAPK signalling pathway­related proteins and genes were decreased. It was found that urantide could effectively block the MAPK signalling pathway by antagonizing the UII/UT system, thus protecting the livers of ALI model rats. Therefore, it was suggested that ALI may be associated with the MAPK signalling pathway, and effective inhibition of the MAPK signalling pathway may be critical in protecting the liver.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Fragmentos de Peptídeos/farmacologia , Urotensinas/farmacologia , Actinas/genética , Actinas/metabolismo , Animais , Tetracloreto de Carbono/toxicidade , Modelos Animais de Doenças , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , MAP Quinase Quinase 4/genética , MAP Quinase Quinase 4/metabolismo , Masculino , Osteopontina/genética , Osteopontina/metabolismo , Fragmentos de Peptídeos/uso terapêutico , Ratos Sprague-Dawley , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Urotensinas/uso terapêutico , Proteínas Quinases p38 Ativadas por Mitógeno/genética , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
7.
Arterioscler Thromb Vasc Biol ; 41(9): e427-e439, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34261328

RESUMO

Objective: Atheromatous fibrous caps are produced by smooth muscle cells (SMCs) that are recruited to the subendothelial space. We tested whether the recruitment mechanisms are the same as in embryonic artery development, which relies prominently on Notch signaling to form the subendothelial medial SMC layers. Approach and Results: Notch elements were expressed in regions of fibrous cap in human and mouse plaques. To assess the causal role of Notch signaling in cap formation, we studied atherosclerosis in mice where the Notch pathway was inactivated in SMCs by conditional knockout of the essential effector transcription factor RBPJ (recombination signal-binding protein for immunoglobulin kappa J region). The recruitment of cap SMCs was significantly reduced without major effects on plaque size. Lineage tracing revealed the accumulation of SMC-derived plaque cells in the cap region was unaltered but that Notch-defective cells failed to re-acquire the SMC phenotype in the cap. Conversely, to analyze whether the loss of Notch signaling is required for SMC-derived cells to accumulate in atherogenesis, we studied atherosclerosis in mice with constitutive activation of Notch signaling in SMCs achieved by conditional expression of the Notch intracellular domain. Forced Notch signaling inhibited the ability of medial SMCs to contribute to plaque cells, including both cap SMCs and osteochondrogenic cells, and significantly reduced atherosclerosis development. Conclusions: Sequential loss and gain of Notch signaling is needed to build the cap SMC population. The shared mechanisms with embryonic arterial media assembly suggest that the cap forms as a neo-media that restores the connection between endothelium and subendothelial SMCs, transiently disrupted in early atherogenesis.


Assuntos
Aterosclerose/metabolismo , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Placa Aterosclerótica , Receptores Notch/metabolismo , Túnica Média/metabolismo , Actinas/genética , Actinas/metabolismo , Animais , Artérias/metabolismo , Artérias/patologia , Aterosclerose/genética , Aterosclerose/patologia , Linhagem da Célula , Células Cultivadas , Progressão da Doença , Fibrose , Humanos , Proteína de Ligação a Sequências Sinal de Recombinação J de Imunoglobina/genética , Proteína de Ligação a Sequências Sinal de Recombinação J de Imunoglobina/metabolismo , Proteína Jagged-1/genética , Proteína Jagged-1/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/patologia , Fenótipo , Ratos , Receptores Notch/genética , Transdução de Sinais , Túnica Média/patologia
8.
Development ; 148(14)2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-34228789

RESUMO

Sound transduction occurs in the hair bundle, the apical compartment of sensory hair cells in the inner ear. The hair bundle is formed of actin-based stereocilia aligned in rows of graded heights. It was previously shown that the GNAI-GPSM2 complex is part of a developmental blueprint that defines the polarized organization of the apical cytoskeleton in hair cells, including stereocilia distribution and elongation. Here, we report a role for multiple PDZ domain (MPDZ) protein during apical hair cell morphogenesis in mouse. We show that MPDZ is enriched at the hair cell apical membrane along with MAGUK p55 subfamily member 5 (MPP5/PALS1) and the Crumbs protein CRB3. MPDZ is required there to maintain the proper segregation of apical blueprint proteins, including GNAI-GPSM2. Loss of the blueprint coincides with misaligned stereocilia placement in Mpdz mutant hair cells, and results in permanently misshapen hair bundles. Graded molecular and structural defects along the cochlea can explain the profile of hearing loss in Mpdz mutants, where deficits are most severe at high frequencies.


Assuntos
Citoesqueleto/metabolismo , Células Ciliadas Auditivas/metabolismo , Domínios PDZ , Actinas/metabolismo , Animais , Cóclea/metabolismo , Orelha Interna/metabolismo , Perda Auditiva/metabolismo , Proteínas de Membrana , Camundongos , Estereocílios/metabolismo
9.
Aging (Albany NY) ; 13(13): 16957-16973, 2021 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-34253690

RESUMO

Many aging related diseases such as cancer implicate the myofibroblast in disease progression. Furthermore genesis of the myofibroblast is associated with manifestation of cellular senescence of unclear significance. In this study we investigated the role of a common regulator, namely telomerase reverse transcriptase (TERT), in order to evaluate the potential significance of this association between both processes. We analyzed the effects of TERT overexpression or deficiency on expression of CDKN2A and ACTA2 as indicators of senescence and differentiation, respectively. We assess binding of TERT or YB-1, a repressor of both genes, to their promoters. TERT repressed both CDKN2A and ACTA2 expression, and abolished stress-induced expression of both genes. Conversely, TERT deficiency enhanced their expression. Altering CDKN2A expression had no effect on ACTA2 expression. Both TERT and YB-1 were shown to bind the CDKN2A promoter but only YB-1 was shown to bind the ACTA2 promoter. TERT overexpression inhibited CDKN2A promoter activity while stimulating YB-1 expression and activation to repress ACTA2 gene. TERT repressed myofibroblast differentiation and senescence via distinct mechanisms. The latter was associated with TERT binding to the CDKN2A promoter, but not to the ACTA2 promoter, which may require interaction with co-factors such as YB-1.


Assuntos
Diferenciação Celular/fisiologia , Senescência Celular/fisiologia , Miofibroblastos/fisiologia , Telomerase/fisiologia , Actinas/metabolismo , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Humanos , Masculino , Regiões Promotoras Genéticas , RNA Interferente Pequeno , Telomerase/biossíntese , Telomerase/genética
10.
Chem Biol Interact ; 346: 109578, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34265256

RESUMO

Current organophosphate (OP) toxicity research now considers potential non-cholinergic mechanisms for these compounds, since the inhibition of acetylcholinesterase (AChE) cannot completely explain all the adverse biological effects of OP. Thanks to the development of new strategies for OP detection, some potential molecular targets have been identified. Among these molecules are several cytoskeletal proteins, including actin, tubulin, intermediate filament proteins, and associated proteins, such as motor proteins, microtubule-associated proteins (MAPs), and cofilin. in vitro, ex vivo, and some in vivo reports have identified alterations in the cytoskeleton following OP exposure, including cell morphology defects, cells detachments, intracellular transport disruption, aberrant mitotic spindle formation, modification of cell motility, and reduced phagocytic capability, which implicate the cytoskeleton in OP toxicity. Here, we reviewed the evidence indicating the cytoskeletal targets of OP compounds, including their strategies, the potential effects of their alterations, and their possible participation in neurotoxicity, embryonic development, cell division, and immunotoxicity related to OP compounds exposure.


Assuntos
Citoesqueleto/metabolismo , Compostos Organofosforados/metabolismo , Actinas/metabolismo , Animais , Carcinogênese , Divisão Celular/efeitos dos fármacos , Desenvolvimento Embrionário/efeitos dos fármacos , Humanos , Proteínas Associadas aos Microtúbulos/metabolismo , Compostos Organofosforados/química , Compostos Organofosforados/toxicidade , Tubulina (Proteína)/metabolismo
11.
Nat Commun ; 12(1): 4086, 2021 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-34215727

RESUMO

Sarcomeres, the basic contractile units of striated muscle, produce the forces driving muscular contraction through cross-bridge interactions between actin-containing thin filaments and myosin II-based thick filaments. Until now, direct visualization of the molecular architecture underlying sarcomere contractility has remained elusive. Here, we use in situ cryo-electron tomography to unveil sarcomere contraction in frozen-hydrated neonatal rat cardiomyocytes. We show that the hexagonal lattice of the thick filaments is already established at the neonatal stage, with an excess of thin filaments outside the trigonal positions. Structural assessment of actin polarity by subtomogram averaging reveals that thin filaments in the fully activated state form overlapping arrays of opposite polarity in the center of the sarcomere. Our approach provides direct evidence for thin filament sliding during muscle contraction and may serve as a basis for structural understanding of thin filament activation and actomyosin interactions inside unperturbed cellular environments.


Assuntos
Actinas/metabolismo , Contração Muscular/fisiologia , Miócitos Cardíacos/fisiologia , Sarcômeros/fisiologia , Citoesqueleto de Actina , Animais , Masculino , Camundongos Endogâmicos C57BL , Músculo Esquelético/química , Músculo Estriado , Miócitos Cardíacos/ultraestrutura , Miofibrilas , Ratos , Ratos Wistar , Sarcômeros/ultraestrutura
12.
Anticancer Res ; 41(8): 4089-4092, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34281879

RESUMO

BACKGROUND/AIM: Serum-derived macrophage activating factor (serum-MAF) is expected to have adjuvant effects through rapid phagocytic activation, which depends on F-actin accumulation in multi-layered membrane ruffles induced within 5 min after serum-MAF addition. This study aimed to elucidate the importance of annexin A2, which is a multifunctional Ca2+-binding protein related to cytoskeletal membrane dynamics, in serum-MAF signalling. MATERIALS AND METHODS: Annexin A2 and F-actin localizations were analyzed via immunostaining and confocal microscopy. Using EGTA as chelator, the role of Ca2+ in serum-MAF signalling was examined. RESULTS: Annexin A2 was found to translocate from the cytosol to the cell cortex within 30 s of serum-MAF stimulation. Ca2+ chelation inhibited the translocation of annexin A2, frill-like structure formation, and phagocytic activation by serum-MAF. CONCLUSION: Annexin A2 and Ca2+ were responsible for the rapid phagocytic activation by serum-MAF. This study provides an understanding of phagocytic activation in macrophages, which could be beneficial for cancer immunotherapy.


Assuntos
Anexina A2/metabolismo , Ativação de Macrófagos , Fatores Ativadores de Macrófagos/sangue , Macrófagos/fisiologia , Actinas/metabolismo , Humanos , Fagocitose , Células THP-1
13.
Nat Commun ; 12(1): 4514, 2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-34301929

RESUMO

Regulation of IP3 receptors (IP3Rs) by IP3 and Ca2+ allows regenerative Ca2+ signals, the smallest being Ca2+ puffs, which arise from coordinated openings of a few clustered IP3Rs. Cells express thousands of mostly mobile IP3Rs, yet Ca2+ puffs occur at a few immobile IP3R clusters. By imaging cells with endogenous IP3Rs tagged with EGFP, we show that KRas-induced actin-interacting protein (KRAP) tethers IP3Rs to actin beneath the plasma membrane. Loss of KRAP abolishes Ca2+ puffs and the global increases in cytosolic Ca2+ concentration evoked by more intense stimulation. Over-expressing KRAP immobilizes additional IP3R clusters and results in more Ca2+ puffs and larger global Ca2+ signals. Endogenous KRAP determines which IP3Rs will respond: it tethers IP3R clusters to actin alongside sites where store-operated Ca2+ entry occurs, licenses IP3Rs to evoke Ca2+ puffs and global cytosolic Ca2+ signals, implicates the actin cytoskeleton in IP3R regulation and may allow local activation of Ca2+ entry.


Assuntos
Actinas/metabolismo , Cálcio/metabolismo , Citosol/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Proteínas de Membrana/metabolismo , Proteínas dos Microfilamentos/metabolismo , Animais , Células HEK293 , Células HeLa , Humanos , Receptores de Inositol 1,4,5-Trifosfato/genética , Proteínas de Membrana/genética , Proteínas dos Microfilamentos/genética , Microscopia de Fluorescência , Ligação Proteica , Interferência de RNA
14.
Nat Commun ; 12(1): 4511, 2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-34301939

RESUMO

Septins are cytoskeletal proteins that assemble into hetero-oligomeric complexes and sense micron-scale membrane curvature. During infection with Shigella flexneri, an invasive enteropathogen, septins restrict actin tail formation by entrapping bacteria in cage-like structures. Here, we reconstitute septin cages in vitro using purified recombinant septin complexes (SEPT2-SEPT6-SEPT7), and study how these recognize bacterial cells and assemble on their surface. We show that septin complexes recognize the pole of growing Shigella cells. An amphipathic helix domain in human SEPT6 enables septins to sense positively curved membranes and entrap bacterial cells. Shigella strains lacking lipopolysaccharide components are more efficiently entrapped in septin cages. Finally, cryo-electron tomography of in vitro cages reveals how septins assemble as filaments on the bacterial cell surface.


Assuntos
Actinas/metabolismo , Disenteria Bacilar/metabolismo , Proteínas Recombinantes/metabolismo , Septinas/metabolismo , Shigella flexneri/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Membrana Celular/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Disenteria Bacilar/microbiologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HeLa , Humanos , Lipopolissacarídeos/metabolismo , Microscopia de Fluorescência , Mutação , Ligação Proteica , Septinas/genética , Shigella flexneri/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
15.
FASEB J ; 35(8): e21679, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34314542

RESUMO

The ability to form a variety of cell-matrix connections is crucial for angiogenesis to take place. Without stable anchorage to the extracellular matrix (ECM), endothelial cells (ECs) are unable to sense, integrate and disseminate growth factor stimulated responses that drive growth of a vascular bed. Neuropilin-2 (NRP2) is a widely expressed membrane-bound multifunctional non-tyrosine kinase receptor, which has previously been implicated in influencing cell adhesion and migration by interacting with α5-integrin and regulating adhesion turnover. α5-integrin, and its ECM ligand fibronectin (FN) are both known to be upregulated during the formation of neo-vasculature. Despite being descriptively annotated as a candidate biomarker for aggressive cancer phenotypes, the EC-specific roles for NRP2 during developmental and pathological angiogenesis remain unexplored. The data reported here support a model whereby NRP2 actively promotes EC adhesion and migration by regulating dynamic cytoskeletal remodeling and by stimulating Rab11-dependent recycling of α5-integrin-p-FAK complexes to newly assembling adhesion sites. Furthermore, temporal depletion of EC-NRP2 in vivo impairs primary tumor growth by disrupting vessel formation. We also demonstrate that EC-NRP2 is required for normal postnatal retinal vascular development, specifically by regulating cell-matrix adhesion. Upon loss of endothelial NRP2, vascular outgrowth from the optic nerve during superficial plexus formation is disrupted, likely due to reduced FAK phosphorylation within sprouting tip cells.


Assuntos
Actinas/metabolismo , Células Endoteliais , Integrina alfa5/metabolismo , Pulmão/irrigação sanguínea , Neovascularização Patológica/metabolismo , Neuropilina-2/fisiologia , Animais , Adesão Celular , Linhagem Celular Tumoral , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Matriz Extracelular/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL
16.
Nat Commun ; 12(1): 4595, 2021 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-34321459

RESUMO

Constriction of the cytokinetic ring, a circular structure of actin filaments, is an essential step during cell division. Mechanical forces driving the constriction are attributed to myosin motor proteins, which slide actin filaments along each other. However, in multiple organisms, ring constriction has been reported to be myosin independent. How actin rings constrict in the absence of motor activity remains unclear. Here, we demonstrate that anillin, a non-motor actin crosslinker, indispensable during cytokinesis, autonomously propels the contractility of actin bundles. Anillin generates contractile forces of tens of pico-Newtons to maximise the lengths of overlaps between bundled actin filaments. The contractility is enhanced by actin disassembly. When multiple actin filaments are arranged into a ring, this contractility leads to ring constriction. Our results indicate that passive actin crosslinkers can substitute for the activity of molecular motors to generate contractile forces in a variety of actin networks, including the cytokinetic ring.


Assuntos
Actinas/metabolismo , Proteínas Contráteis/metabolismo , Miosinas/metabolismo , Citoesqueleto de Actina/metabolismo , Actomiosina/metabolismo , Animais , Divisão Celular , Proteínas Contráteis/genética , Citocinese , Drosophila melanogaster/metabolismo , Humanos , Proteínas dos Microfilamentos
17.
Int J Mol Sci ; 22(14)2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34299022

RESUMO

Neuronal cell adhesion molecule 2 (NCAM2) is a membrane protein with an important role in the morphological development of neurons. In the cortex and the hippocampus, NCAM2 is essential for proper neuronal differentiation, dendritic and axonal outgrowth and synapse formation. However, little is known about NCAM2 functional mechanisms and its interactive partners during brain development. Here we used mass spectrometry to study the molecular interactome of NCAM2 in the second postnatal week of the mouse cerebral cortex. We found that NCAM2 interacts with >100 proteins involved in numerous processes, including neuronal morphogenesis and synaptogenesis. We validated the most relevant interactors, including Neurofilaments (NEFs), Microtubule-associated protein 2 (MAP2), Calcium/calmodulin kinase II alpha (CaMKIIα), Actin and Nogo. An in silico analysis of the cytosolic tail of the NCAM2.1 isoform revealed specific phosphorylation site motifs with a putative affinity for some of these interactors. Our results expand the knowledge of NCAM2 interactome and confirm the key role of NCAM2 in cytoskeleton organization, neuronal morphogenesis and synaptogenesis. These findings are of interest in explaining the phenotypes observed in different pathologies with alterations in the NCAM2 gene.


Assuntos
Córtex Cerebral/metabolismo , Citoesqueleto/metabolismo , Espectrometria de Massas , Moléculas de Adesão de Célula Nervosa/metabolismo , Neurogênese , Neurônios/metabolismo , Actinas/metabolismo , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Córtex Cerebral/crescimento & desenvolvimento , Biologia Computacional , Citoplasma/genética , Citoplasma/metabolismo , Bases de Dados de Compostos Químicos , Ontologia Genética , Técnicas In Vitro , Filamentos Intermediários/metabolismo , Camundongos , Proteínas Associadas aos Microtúbulos/metabolismo , Neurogênese/genética , Proteínas Nogo , Fosforilação , Domínios Proteicos , Mapas de Interação de Proteínas , Proteoma/genética , Proteoma/metabolismo , Transcriptoma/genética
18.
Int J Mol Sci ; 22(12)2021 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-34204776

RESUMO

Point mutations in the genes encoding the skeletal muscle isoforms of tropomyosin can cause a range of muscle diseases. The amino acid substitution of Arg for Pro residue in the 90th position (R90P) in γ-tropomyosin (Tpm3.12) is associated with congenital fiber type disproportion and muscle weakness. The molecular mechanisms underlying muscle dysfunction in this disease remain unclear. Here, we observed that this mutation causes an abnormally high Ca2+-sensitivity of myofilaments in vitro and in muscle fibers. To determine the critical conformational changes that myosin, actin, and tropomyosin undergo during the ATPase cycle and the alterations in these changes caused by R90P replacement in Tpm3.12, we used polarized fluorimetry. It was shown that the R90P mutation inhibits the ability of tropomyosin to shift towards the outer domains of actin, which is accompanied by the almost complete depression of troponin's ability to switch actin monomers off and to reduce the amount of the myosin heads weakly bound to F-actin at a low Ca2+. These changes in the behavior of tropomyosin and the troponin-tropomyosin complex, as well as in the balance of strongly and weakly bound myosin heads in the ATPase cycle may underlie the occurrence of both abnormally high Ca2+-sensitivity and muscle weakness. BDM, an inhibitor of myosin ATPase activity, and W7, a troponin C antagonist, restore the ability of tropomyosin for Ca2+-dependent movement and the ability of the troponin-tropomyosin complex to switch actin monomers off, demonstrating a weakening of the damaging effect of the R90P mutation on muscle contractility.


Assuntos
Contração Muscular/genética , Mutação/genética , Oximas/farmacologia , Sulfonamidas/farmacologia , Tropomiosina/genética , Actinas/metabolismo , Animais , Cálcio/metabolismo , Contração Muscular/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Miofibrilas/efeitos dos fármacos , Miofibrilas/metabolismo , Miosinas/metabolismo , Coelhos , Troponina/metabolismo
19.
J Cell Sci ; 134(12)2021 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-34152390

RESUMO

Cytokinesis occurs at the end of mitosis/meiosis wherein the cytoplasms of daughter cells are separated. Before abscission, an intercellular bridge containing the remaining furrowing machinery, mitotic spindle and actin cytoskeleton connects the two daughter cells. To remove this actin and allow for the separation of daughter cells, Rab35 vesicles, loaded with the actin oxidizer MICAL1 and the inositol polyphosphate 5-phosphatase OCRL, are recruited to the midbody in a fine-tuned spatiotemporal manner. However, importantly, the means by which these vesicles are recruited is currently unclear. Here, we demonstrate that Rab11FIP1 is recruited to the midbody after Rab35 to scaffold it at the bridge and maintain Rab35 in this region. In the absence of Rab11FIP1, Rab35 dramatically drops from the midbody, inducing defects, such as cytokinetic delays and binucleation due to actin overaccumulation at the intercellular bridge, which can be rescued with Latrunculin A treatment. Importantly, we show that Rab11FIP1 is critical for Rab35 function in actin removal prior to cytokinesis. This article has an associated First Person interview with the first author of the paper.


Assuntos
Actinas , Citocinese , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Células HeLa , Humanos , Proteínas de Membrana , Proteínas dos Microfilamentos/metabolismo , Mitose , Oxigenases de Função Mista , Fuso Acromático/metabolismo , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
20.
Toxins (Basel) ; 13(6)2021 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071730

RESUMO

The clinically highly relevant Clostridioides (C.) difficile releases several AB-type toxins that cause diseases such as diarrhea and pseudomembranous colitis. In addition to the main virulence factors Rho/Ras-glycosylating toxins TcdA and TcdB, hypervirulent strains produce the binary AB-type toxin CDT. CDT consists of two separate proteins. The binding/translocation B-component CDTb facilitates uptake and translocation of the enzyme A-component CDTa to the cytosol of cells. Here, CDTa ADP-ribosylates G-actin, resulting in depolymerization of the actin cytoskeleton. We previously showed that CDTb exhibits cytotoxicity in the absence of CDTa, which is most likely due to pore formation in the cytoplasmic membrane. Here, we further investigated this cytotoxic effect and showed that CDTb impairs CaCo-2 cell viability and leads to redistribution of F-actin without affecting tubulin structures. CDTb was detected at the cytoplasmic membrane in addition to its endosomal localization if CDTb was applied alone. Chloroquine and several of its derivatives, which were previously identified as toxin pore blockers, inhibited intoxication of Vero, HCT116, and CaCo-2 cells by CDTb and CDTb pores in vitro. These results further strengthen pore formation by CDTb in the cytoplasmic membrane as the underlying cytotoxic mechanism and identify pharmacological pore blockers as potent inhibitors of cytotoxicity induced by CDTb and CDTa plus CDTb.


Assuntos
Toxinas Bacterianas/antagonistas & inibidores , Clostridioides difficile/patogenicidade , Actinas/metabolismo , Animais , Toxinas Bacterianas/farmacologia , Células CACO-2 , Cálcio/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Chlorocebus aethiops , Cloroquina/farmacologia , Humanos , Células Vero
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