Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.297
Filtrar
1.
Int J Mol Sci ; 25(13)2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-39000353

RESUMO

Connexins (Cxs) are transmembrane proteins that assemble into gap junction channels (GJCs) and hemichannels (HCs). Previous researches support the involvement of Rho GTPases and actin microfilaments in the trafficking of Cxs, formation of GJCs plaques, and regulation of channel activity. Nonetheless, it remains uncertain whether distinct types of Cxs HCs and GJCs respond differently to Rho GTPases or changes in actin polymerization/depolymerization dynamics. Our investigation revealed that inhibiting RhoA, a small GTPase that controls actin polymerization, or disrupting actin microfilaments with cytochalasin B (Cyto-B), resulted in reduced GJCs plaque size at appositional membranes and increased transport of HCs to non-appositional plasma membrane regions. Notably, these effects were consistent across different Cx types, since Cx26 and Cx43 exhibited similar responses, despite having distinct trafficking routes to the plasma membrane. Functional assessments showed that RhoA inhibition and actin depolymerization decreased the activity of Cx43 GJCs while significantly increasing HC activity. However, the functional status of GJCs and HCs composed of Cx26 remained unaffected. These results support the hypothesis that RhoA, through its control of the actin cytoskeleton, facilitates the transport of HCs to appositional cell membranes for GJCs formation while simultaneously limiting the positioning of free HCs at non-appositional cell membranes, independently of Cx type. This dynamic regulation promotes intercellular communications and reduces non-selective plasma membrane permeability through a Cx-type dependent mechanism, whereby the activity of Cx43 HCs and GJCs are differentially affected but Cx26 channels remain unchanged.


Assuntos
Citoesqueleto de Actina , Conexina 26 , Conexina 43 , Junções Comunicantes , Proteína rhoA de Ligação ao GTP , Citoesqueleto de Actina/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo , Junções Comunicantes/metabolismo , Conexina 43/metabolismo , Conexina 26/metabolismo , Humanos , Animais , Membrana Celular/metabolismo , Actinas/metabolismo
2.
Int J Mol Sci ; 25(13)2024 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-38999987

RESUMO

The actin cytoskeleton is one of the most important players in cell motility, adhesion, division, and functioning. The regulation of specific microfilament formation largely determines cellular functions. The main actin-binding protein in animal cells is tropomyosin (Tpm). The unique structural and functional diversity of microfilaments is achieved through the diversity of Tpm isoforms. In our work, we studied the properties of the cytoplasmic isoforms Tpm1.8 and Tpm1.9. The results showed that these isoforms are highly thermostable and differ in the stability of their central and C-terminal fragments. The properties of these isoforms were largely determined by the 6th exons. Thus, the strength of the end-to-end interactions, as well as the affinity of the Tpm molecule for F-actin, differed between the Tpm1.8 and Tpm1.9 isoforms. They were determined by whether an alternative internal exon, 6a or 6b, was included in the Tpm isoform structure. The strong interactions of the Tpm1.8 and Tpm1.9 isoforms with F-actin led to the formation of rigid actin filaments, the stiffness of which was measured using an optical trap. It is quite possible that the structural and functional features of the Tpm isoforms largely determine the appearance of these isoforms in the rigid actin structures of the cell cortex.


Assuntos
Citoesqueleto de Actina , Actinas , Isoformas de Proteínas , Tropomiosina , Tropomiosina/metabolismo , Tropomiosina/química , Tropomiosina/genética , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Citoesqueleto de Actina/metabolismo , Animais , Actinas/metabolismo , Actinas/química , Citoplasma/metabolismo , Humanos , Éxons , Ligação Proteica , Estabilidade Proteica
3.
Nat Commun ; 15(1): 5840, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38992021

RESUMO

Within a shared cytoplasm, filamentous actin (F-actin) plays numerous and critical roles across the cell body. Cells rely on actin-binding proteins (ABPs) to organize F-actin and to integrate its polymeric characteristics into diverse cellular processes. Yet, the multitude of ABPs that engage with and shape F-actin make studying a single ABP's influence on cellular activities a significant challenge. Moreover, without a means of manipulating actin-binding subcellularly, harnessing the F-actin cytoskeleton for synthetic biology purposes remains elusive. Here, we describe a suite of designed proteins, Controllable Actin-binding Switch Tools (CASTs), whose actin-binding behavior can be controlled with external stimuli. CASTs were developed that respond to different external inputs, providing options for turn-on kinetics and enabling orthogonality and multiplexing. Being genetically encoded, we show that CASTs can be inserted into native protein sequences to control F-actin association locally and engineered into structures to control cell and tissue shape and behavior.


Assuntos
Citoesqueleto de Actina , Actinas , Proteínas dos Microfilamentos , Ligação Proteica , Actinas/metabolismo , Proteínas dos Microfilamentos/metabolismo , Proteínas dos Microfilamentos/genética , Citoesqueleto de Actina/metabolismo , Humanos , Animais , Cinética , Engenharia de Proteínas/métodos
4.
Commun Biol ; 7(1): 830, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38992143

RESUMO

Decidualization of the human endometrium is critical for establishing pregnancy and is entailed by differentiation of endometrial stromal cells (ESCs) into decidual cells. During decidualization, the actin cytoskeleton is dynamically reorganized for the ESCs' morphological and functional changes. Although actin dynamically alters its polymerized state upon external stimuli not only in the cytoplasm, but also in the nucleus, nuclear actin dynamics during decidualization have not been elucidated. Here, we show that nuclear actin was specifically assembled during decidualization of human ESCs. This decidualization-specific formation of nuclear actin filaments was disassembled following the withdrawal of the decidualization stimulus, suggesting its reversible process. Mechanistically, RNA-seq analyses revealed that the forced disassembly of nuclear actin resulted in the suppression of decidualization, accompanied with the abnormal upregulation of cell proliferation genes, leading to incomplete cell cycle arrest. CCAAT/enhancer-binding protein beta (C/EBPß), an important regulator for decidualization, was responsible for downregulation of the nuclear actin exporter, thus accelerating nuclear actin accumulation and its assembly for decidualization. Taken together, we demonstrate that decidualization-specific nuclear actin assembly induces cell cycle arrest for establishing the decidualized state of ESCs. We propose that not only the cytoplasmic actin, but also nuclear actin dynamics profoundly affect decidualization process in humans for ensuring pregnancy.


Assuntos
Actinas , Núcleo Celular , Decídua , Endométrio , Células Estromais , Humanos , Feminino , Células Estromais/metabolismo , Actinas/metabolismo , Endométrio/citologia , Endométrio/metabolismo , Decídua/metabolismo , Decídua/citologia , Núcleo Celular/metabolismo , Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Proteína beta Intensificadora de Ligação a CCAAT/genética , Gravidez , Diferenciação Celular , Proliferação de Células , Citoesqueleto de Actina/metabolismo
5.
Commun Biol ; 7(1): 840, 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38987288

RESUMO

The architecture of the actin cortex determines the generation and transmission of stresses, during key events from cell division to migration. However, its impact on myosin-induced cell shape changes remains unclear. Here, we reconstitute a minimal model of the actomyosin cortex with branched or linear F-actin architecture within giant unilamellar vesicles (GUVs, liposomes). Upon light activation of myosin, neither the branched nor linear F-actin architecture alone induces significant liposome shape changes. The branched F-actin network forms an integrated, membrane-bound "no-slip boundary" -like cortex that attenuates actomyosin contractility. By contrast, the linear F-actin network forms an unintegrated "slip boundary" -like cortex, where actin asters form without inducing membrane deformations. Notably, liposomes undergo significant deformations at an optimized balance of branched and linear F-actin networks. Our findings highlight the pivotal roles of branched F-actin in force transmission and linear F-actin in force generation to yield membrane shape changes.


Assuntos
Actinas , Membrana Celular , Miosinas , Actinas/metabolismo , Membrana Celular/metabolismo , Miosinas/metabolismo , Forma Celular , Animais , Actomiosina/metabolismo , Lipossomas Unilamelares/metabolismo , Lipossomas Unilamelares/química , Biomimética , Lipossomos/metabolismo , Lipossomos/química , Modelos Biológicos , Citoesqueleto de Actina/metabolismo
6.
Proc Natl Acad Sci U S A ; 121(29): e2408156121, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-38980907

RESUMO

After ATP-actin monomers assemble filaments, the ATP's [Formula: see text]-phosphate is hydrolyzedwithin seconds and dissociates over minutes. We used all-atom molecular dynamics simulations to sample the release of phosphate from filaments and study residues that gate release. Dissociation of phosphate from Mg2+ is rate limiting and associated with an energy barrier of 20 kcal/mol, consistent with experimental rates of phosphate release. Phosphate then diffuses within an internal cavity toward a gate formed by R177, as suggested in prior computational studies and cryo-EM structures. The gate is closed when R177 hydrogen bonds with N111 and is open when R177 forms a salt bridge with D179. Most of the time, interactions of R177 with other residues occlude the phosphate release pathway. Machine learning analysis reveals that the occluding interactions fluctuate rapidly, underscoring the secondary role of backdoor gate opening in Pi release, in contrast with the previous hypothesis that gate opening is the primary event.


Assuntos
Citoesqueleto de Actina , Trifosfato de Adenosina , Simulação de Dinâmica Molecular , Fosfatos , Fosfatos/metabolismo , Fosfatos/química , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/química , Trifosfato de Adenosina/metabolismo , Actinas/metabolismo , Actinas/química , Ligação de Hidrogênio , Magnésio/metabolismo , Magnésio/química , Microscopia Crioeletrônica
7.
Nat Commun ; 15(1): 5967, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39013865

RESUMO

Crosstalk between the actin and microtubule cytoskeletons is important for many cellular processes. Recent studies have shown that microtubules and F-actin can assemble to form a composite structure where F-actin occupies the microtubule lumen. Whether these cytoskeletal hybrids exist in physiological settings and how they are formed is unclear. Here, we show that the short-crossover Class I actin filament previously identified inside microtubules in human HAP1 cells is cofilin-bound F-actin. Lumenal F-actin can be reconstituted in vitro, but cofilin is not essential. Moreover, actin filaments with both cofilin-bound and canonical morphologies reside within human platelet microtubules under physiological conditions. We propose that stress placed upon the microtubule network during motor-driven microtubule looping and sliding may facilitate the incorporation of actin into microtubules.


Assuntos
Citoesqueleto de Actina , Actinas , Plaquetas , Microtúbulos , Microtúbulos/metabolismo , Humanos , Citoesqueleto de Actina/metabolismo , Plaquetas/metabolismo , Actinas/metabolismo , Fatores de Despolimerização de Actina/metabolismo , Microscopia Crioeletrônica
8.
Proc Natl Acad Sci U S A ; 121(29): e2321647121, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-38995965

RESUMO

Precise segregation of chromosomes during mitosis requires assembly of a bipolar mitotic spindle followed by correct attachment of microtubules to the kinetochores. This highly spatiotemporally organized process is controlled by various mitotic kinases and molecular motors. We have recently shown that Casein Kinase 1 (CK1) promotes timely progression through mitosis by phosphorylating FAM110A leading to its enrichment at spindle poles. However, the mechanism by which FAM110A exerts its function in mitosis is unknown. Using structure prediction and a set of deletion mutants, we mapped here the interaction of the N- and C-terminal domains of FAM110A with actin and tubulin, respectively. Next, we found that the FAM110A-Δ40-61 mutant deficient in actin binding failed to rescue defects in chromosomal alignment caused by depletion of endogenous FAM110A. Depletion of FAM110A impaired assembly of F-actin in the proximity of spindle poles and was rescued by expression of the wild-type FAM110A, but not the FAM110A-Δ40-61 mutant. Purified FAM110A promoted binding of F-actin to microtubules as well as bundling of actin filaments in vitro. Finally, we found that the inhibition of CK1 impaired spindle actin formation and delayed progression through mitosis. We propose that CK1 and FAM110A promote timely progression through mitosis by mediating the interaction between spindle microtubules and filamentous actin to ensure proper mitotic spindle formation.


Assuntos
Citoesqueleto de Actina , Microtúbulos , Mitose , Fuso Acromático , Microtúbulos/metabolismo , Fuso Acromático/metabolismo , Humanos , Citoesqueleto de Actina/metabolismo , Actinas/metabolismo , Células HeLa , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Caseína Quinase I/metabolismo , Caseína Quinase I/genética , Ligação Proteica
9.
Commun Biol ; 7(1): 832, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38977899

RESUMO

An important question in cell biology is how cytoskeletal proteins evolved and drove the development of novel structures and functions. Here we address the origin of SPIRE actin nucleators. Mammalian SPIREs work with RAB GTPases, formin (FMN)-subgroup actin assembly proteins and class-5 myosin (MYO5) motors to transport organelles along actin filaments towards the cell membrane. However, the origin and extent of functional conservation of SPIRE among species is unknown. Our sequence searches show that SPIRE exist throughout holozoans (animals and their closest single-celled relatives), but not other eukaryotes. SPIRE from unicellular holozoans (choanoflagellate), interacts with RAB, FMN and MYO5 proteins, nucleates actin filaments and complements mammalian SPIRE function in organelle transport. Meanwhile SPIRE and MYO5 proteins colocalise to organelles in Salpingoeca rosetta choanoflagellates. Based on these observations we propose that SPIRE originated in unicellular ancestors of animals providing an actin-myosin driven exocytic transport mechanism that may have contributed to the evolution of complex multicellular animals.


Assuntos
Actomiosina , Organelas , Animais , Organelas/metabolismo , Actomiosina/metabolismo , Proteínas dos Microfilamentos/metabolismo , Proteínas dos Microfilamentos/genética , Miosina Tipo V/metabolismo , Miosina Tipo V/genética , Actinas/metabolismo , Humanos , Coanoflagelados/metabolismo , Citoesqueleto de Actina/metabolismo , Evolução Biológica , Evolução Molecular , Forminas/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Filogenia , Proteínas Nucleares
10.
J Cell Biol ; 223(9)2024 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-39013281

RESUMO

We previously identified talin rod domain-containing protein 1 (TLNRD1) as a potent actin-bundling protein in vitro. Here, we report that TLNRD1 is expressed in the vasculature in vivo. Its depletion leads to vascular abnormalities in vivo and modulation of endothelial cell monolayer integrity in vitro. We demonstrate that TLNRD1 is a component of the cerebral cavernous malformations (CCM) complex through its direct interaction with CCM2, which is mediated by a hydrophobic C-terminal helix in CCM2 that attaches to a hydrophobic groove on the four-helix domain of TLNRD1. Disruption of this binding interface leads to CCM2 and TLNRD1 accumulation in the nucleus and actin fibers. Our findings indicate that CCM2 controls TLNRD1 localization to the cytoplasm and inhibits its actin-bundling activity and that the CCM2-TLNRD1 interaction impacts endothelial actin stress fiber and focal adhesion formation. Based on these results, we propose a new pathway by which the CCM complex modulates the actin cytoskeleton and vascular integrity.


Assuntos
Hemangioma Cavernoso do Sistema Nervoso Central , Células Endoteliais da Veia Umbilical Humana , Humanos , Animais , Hemangioma Cavernoso do Sistema Nervoso Central/metabolismo , Hemangioma Cavernoso do Sistema Nervoso Central/patologia , Hemangioma Cavernoso do Sistema Nervoso Central/genética , Células Endoteliais da Veia Umbilical Humana/metabolismo , Células Endoteliais/metabolismo , Adesões Focais/metabolismo , Proteínas de Transporte/metabolismo , Proteínas de Transporte/genética , Fibras de Estresse/metabolismo , Actinas/metabolismo , Citoesqueleto de Actina/metabolismo , Ligação Proteica , Camundongos , Núcleo Celular/metabolismo , Talina
11.
PLoS Genet ; 20(6): e1011101, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38905299

RESUMO

Filamins are mechanosensitive actin crosslinking proteins that organize the actin cytoskeleton in a variety of shapes and tissues. In muscles, filamin crosslinks actin filaments from opposing sarcomeres, the smallest contractile units of muscles. This happens at the Z-disc, the actin-organizing center of sarcomeres. In flies and vertebrates, filamin mutations lead to fragile muscles that appear ruptured, suggesting filamin helps counteract muscle rupturing during muscle contractions by providing elastic support and/or through signaling. An elastic region at the C-terminus of filamin is called the mechanosensitive region and has been proposed to sense and counteract contractile damage. Here we use molecularly defined mutants and microscopy analysis of the Drosophila indirect flight muscles to investigate the molecular details by which filamin provides cohesion to the Z-disc. We made novel filamin mutations affecting the C-terminal region to interrogate the mechanosensitive region and detected three Z-disc phenotypes: dissociation of actin filaments, Z-disc rupture, and Z-disc enlargement. We tested a constitutively closed filamin mutant, which prevents the elastic changes in the mechanosensitive region and results in ruptured Z-discs, and a constitutively open mutant which has the opposite elastic effect on the mechanosensitive region and gives rise to enlarged Z-discs. Finally, we show that muscle contraction is required for Z-disc rupture. We propose that filamin senses myofibril damage by elastic changes in its mechanosensory region, stabilizes the Z-disc, and counteracts contractile damage at the Z-disc.


Assuntos
Citoesqueleto de Actina , Proteínas de Drosophila , Drosophila melanogaster , Filaminas , Contração Muscular , Mutação , Miofibrilas , Animais , Filaminas/metabolismo , Filaminas/genética , Miofibrilas/metabolismo , Miofibrilas/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Contração Muscular/genética , Contração Muscular/fisiologia , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/genética , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Sarcômeros/metabolismo , Sarcômeros/genética , Mecanotransdução Celular/genética , Fenótipo
12.
Development ; 151(13)2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38869008

RESUMO

Cofilin, an actin-severing protein, plays key roles in muscle sarcomere addition and maintenance. Our previous work found that Drosophila cofilin (DmCFL) knockdown in muscle causes progressive deterioration of muscle structure and function and produces features seen in nemaline myopathy caused by cofilin mutations. We hypothesized that disruption of actin cytoskeleton dynamics by DmCFL knockdown would impact other aspects of muscle development, and, thus, conducted an RNA-sequencing analysis that unexpectedly revealed upregulated expression of numerous neuromuscular junction (NMJ) genes. We found that DmCFL is enriched in the muscle postsynaptic compartment and that DmCFL muscle knockdown causes F-actin disorganization in this subcellular domain prior to the sarcomere defects observed later in development. Despite NMJ gene expression changes, we found no significant changes in gross presynaptic Bruchpilot active zones or total postsynaptic glutamate receptor levels. However, DmCFL knockdown resulted in mislocalization of GluRIIA class glutamate receptors in more deteriorated muscles and strongly impaired NMJ transmission strength. These findings expand our understanding of the roles of cofilin in muscle to include NMJ structural development and suggest that NMJ defects may contribute to the pathophysiology of nemaline myopathy.


Assuntos
Proteínas de Drosophila , Drosophila melanogaster , Junção Neuromuscular , Transmissão Sináptica , Animais , Junção Neuromuscular/metabolismo , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Drosophila melanogaster/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Fatores de Despolimerização de Actina/metabolismo , Fatores de Despolimerização de Actina/genética , Actinas/metabolismo , Sarcômeros/metabolismo , Técnicas de Silenciamento de Genes , Citoesqueleto de Actina/metabolismo , Miopatias da Nemalina/metabolismo , Miopatias da Nemalina/genética , Miopatias da Nemalina/patologia
13.
Nat Commun ; 15(1): 5448, 2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-38937444

RESUMO

Flowering plants rely on the polarized growth of pollen tubes to deliver sperm cells (SCs) to the embryo sac for double fertilization. In pollen, the vegetative nucleus (VN) and two SCs form the male germ unit (MGU). However, the mechanism underlying directional transportation of MGU is not well understood. In this study, we provide the first full picture of the dynamic interplay among microtubules, actin filaments, and MGU during pollen germination and tube growth. Depolymerization of microtubules and inhibition of kinesin activity result in an increased velocity and magnified amplitude of VN's forward and backward movement. Pharmacological washout experiments further suggest that microtubules participate in coordinating the directional movement of MGU. In contrast, suppression of the actomyosin system leads to a reduced velocity of VN mobility but without a moving pattern change. Moreover, detailed observation shows that the direction and velocity of VN's movement are in close correlations with those of the actomyosin-driven cytoplasmic streaming surrounding VN. Therefore, we propose that while actomyosin-based cytoplasmic streaming influences on the oscillational movement of MGU, microtubules and kinesins avoid MGU drifting with the cytoplasmic streaming and act as the major regulator for fine-tuning the proper positioning and directional migration of MGU in pollen.


Assuntos
Citoesqueleto de Actina , Actomiosina , Cinesinas , Microtúbulos , Pólen , Microtúbulos/metabolismo , Citoesqueleto de Actina/metabolismo , Cinesinas/metabolismo , Pólen/metabolismo , Actomiosina/metabolismo , Tubo Polínico/metabolismo , Tubo Polínico/crescimento & desenvolvimento , Núcleo Celular/metabolismo , Arabidopsis/metabolismo , Corrente Citoplasmática , Germinação/fisiologia
14.
In Vivo ; 38(4): 1571-1578, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38936915

RESUMO

BACKGROUND/AIM: Cold physical plasma (CPP) has emerged as an effective therapy in oncology by inducing cytotoxic effects in various cancer cells, including chondrosarcoma (CS), Ewing's sarcoma (ES), and osteosarcoma (OS). The current study investigated the impact of CPP on cell motility in CS (CAL-78), ES (A673), and OS (U2-OS) cell lines, focusing on the actin cytoskeleton. MATERIALS AND METHODS: The CASY Cell Counter and Analyzer was used to study cell proliferation and determine the optimal concentrations of fetal calf serum to maintain viability without stimulation of cell proliferation. CellTiter-BlueCell viability assay was used to determine the effects of CPP on the viability of bone sarcoma cells. The Radius assay was used to determine cell migration. Staining for Deoxyribonuclease I, G-actin, and F-actin was used to assay for the effects on the cytoskeleton. RESULTS: Reductions in cell viability and motility were observed across all cell lines following CPP treatment. CPP induced changes in the actin cytoskeleton, leading to decreased cell motility. CONCLUSION: CPP effectively reduces the motility of bone sarcoma cells by altering the actin cytoskeleton. These findings underscore CPP's potential as a therapeutic tool for bone sarcomas and highlight the need for further research in this area.


Assuntos
Citoesqueleto de Actina , Neoplasias Ósseas , Movimento Celular , Proliferação de Células , Sobrevivência Celular , Citoesqueleto , Gases em Plasma , Humanos , Movimento Celular/efeitos dos fármacos , Gases em Plasma/farmacologia , Linhagem Celular Tumoral , Neoplasias Ósseas/patologia , Neoplasias Ósseas/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Citoesqueleto/metabolismo , Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/efeitos dos fármacos , Osteossarcoma/patologia , Osteossarcoma/metabolismo , Actinas/metabolismo , Sarcoma/patologia , Sarcoma/metabolismo
15.
J Integr Neurosci ; 23(6): 118, 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38940085

RESUMO

BACKGROUND: Alcohol abuse, a prevalent global health issue, is associated with the onset of cognitive impairment and neurodegeneration. Actin filaments (F-actin) and microtubules (MTs) polymerized from monomeric globular actin (G-actin) and tubulin form the structural basis of the neuronal cytoskeleton. Precise regulation of the assembly and disassembly of these cytoskeletal proteins, and their dynamic balance, play a pivotal role in regulating neuronal morphology and function. Nevertheless, the effect of prolonged alcohol exposure on cytoskeleton dynamics is not fully understood. This study investigates the chronic effects of alcohol on cognitive ability, neuronal morphology and cytoskeleton dynamics in the mouse hippocampus. METHODS: Mice were provided ad libitum access to 5% (v/v) alcohol in drinking water and were intragastrically administered 30% (v/v, 6.0 g/kg/day) alcohol for six weeks during adulthood. Cognitive functions were then evaluated using the Y maze, novel object recognition and Morris water maze tests. Hippocampal histomorphology was assessed through hematoxylin-eosin (HE) and Nissl staining. The polymerized and depolymerized states of actin cytoskeleton and microtubules were separated using two commercial assay kits and quantified by Western blot analysis. RESULTS: Mice chronically exposed to alcohol exhibited significant deficits in spatial and recognition memory as evidenced by behavioral tests. Histological analysis revealed notable hippocampal damage and neuronal loss. Decreased ratios of F-actin/G-actin and MT/tubulin, along with reduced levels of polymerized F-actin and MTs, were found in the hippocampus of alcohol-treated mice. CONCLUSIONS: Our findings suggest that chronic alcohol consumption disrupted the assembly of the actin cytoskeleton and MTs in the hippocampus, potentially contributing to the cognitive deficits and pathological injury induced by chronic alcohol intoxication.


Assuntos
Citoesqueleto de Actina , Etanol , Hipocampo , Microtúbulos , Animais , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Citoesqueleto de Actina/efeitos dos fármacos , Citoesqueleto de Actina/metabolismo , Masculino , Etanol/farmacologia , Etanol/administração & dosagem , Camundongos , Camundongos Endogâmicos C57BL , Depressores do Sistema Nervoso Central/farmacologia , Depressores do Sistema Nervoso Central/administração & dosagem , Modelos Animais de Doenças , Comportamento Animal/efeitos dos fármacos
16.
Eur J Cell Biol ; 103(2): 151428, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38850712

RESUMO

Actin organization is crucial for establishing cell polarity, which influences processes such as directed cell motility and division. Despite its critical role in living organisms, achieving similar polarity in synthetic cells remains challenging. In this study, we employ a bottom-up approach to investigate how molecular crowders facilitate the formation of cortex-like actin networks and how these networks localize and organize based on membrane shape. Using giant unilamellar vesicles (GUVs) as models for cell membranes, we show that actin filaments can arrange along the membrane to form cortex-like structures. Notably, this organization is achieved using only actin and crowders as a minimal set of components. We utilize surface micropatterning to examine actin filament organization in deformed GUVs adhered to various pattern shapes. Our findings indicate that at the periphery of spherical GUVs, actin bundles align along the membrane. However, in highly curved regions of adhered GUVs, actin bundles avoid crossing the highly curved edges perpendicular to the adhesion site and instead remain in the lower curved regions by aligning parallel to the micropatterned surface. Furthermore, the actin bundles increase the stiffness of the GUVs, effectively counteracting strong deformations when GUVs adhere to micropatterns. This finding is corroborated by real-time deformability cytometry on GUVs with synthetic actin cortices. By precisely manipulating the shape of GUVs, our study provides a minimal system to investigate the interplay between actin structures and the membrane. Our findings provide insights into the spatial organization of actin structures within crowded environments, specifically inside GUVs that resemble the size and shape of cells. This study advances our understanding of actin network organization and functionality within cell-sized compartments.


Assuntos
Citoesqueleto de Actina , Membrana Celular , Lipossomas Unilamelares , Citoesqueleto de Actina/metabolismo , Lipossomas Unilamelares/metabolismo , Lipossomas Unilamelares/química , Membrana Celular/metabolismo , Actinas/metabolismo , Animais
17.
Cell Mol Life Sci ; 81(1): 248, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38832964

RESUMO

Contractile actomyosin bundles play crucial roles in various physiological processes, including cell migration, morphogenesis, and muscle contraction. The intricate assembly of actomyosin bundles involves the precise alignment and fusion of myosin II filaments, yet the underlying mechanisms and factors involved in these processes remain elusive. Our study reveals that LUZP1 plays a central role in orchestrating the maturation of thick actomyosin bundles. Loss of LUZP1 caused abnormal cell morphogenesis, migration, and the ability to exert forces on the environment. Importantly, knockout of LUZP1 results in significant defects in the concatenation and persistent association of myosin II filaments, severely impairing the assembly of myosin II stacks. The disruption of these processes in LUZP1 knockout cells provides mechanistic insights into the defective assembly of thick ventral stress fibers and the associated cellular contractility abnormalities. Overall, these results significantly contribute to our understanding of the molecular mechanism involved in actomyosin bundle formation and highlight the essential role of LUZP1 in this process.


Assuntos
Actomiosina , Movimento Celular , Contração Muscular , Miosina Tipo II , Humanos , Citoesqueleto de Actina/metabolismo , Actomiosina/metabolismo , Contração Muscular/fisiologia , Miosina Tipo II/metabolismo , Miosina Tipo II/genética
18.
J Cell Sci ; 137(12)2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38832513

RESUMO

Division plane positioning is crucial for proper growth and development in many organisms. In plants, the division plane is established before mitosis, by accumulation of a cytoskeletal structure called the preprophase band (PPB). The PPB is thought to be essential for recruitment of division site-localized proteins, which remain at the division site after the PPB disassembles. Here, we show that the division site-localized protein TANGLED1 (TAN1) is recruited independently of the PPB to the cell cortex by the plant cytokinetic machinery, the phragmoplast, from experiments using both the PPB-defective mutant discordia1 (dcd1) and chemical treatments that disrupt the phragmoplast in maize. TAN1 recruitment to de novo sites on the cortex is partially dependent on intact actin filaments and the myosin XI motor protein OPAQUE1 (O1). These data imply a yet unknown role for TAN1 and possibly other division site-localized proteins during the last stages of cell division when the phragmoplast touches the cell cortex to complete cytokinesis.


Assuntos
Citocinese , Proteínas de Plantas , Zea mays , Zea mays/metabolismo , Zea mays/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Citoesqueleto de Actina/metabolismo
19.
J Cell Biol ; 223(9)2024 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-38869473

RESUMO

At each cell division, nanometer-scale motors and microtubules give rise to the micron-scale spindle. Many mitotic motors step helically around microtubules in vitro, and most are predicted to twist the spindle in a left-handed direction. However, the human spindle exhibits only slight global twist, raising the question of how these molecular torques are balanced. Here, we find that anaphase spindles in the epithelial cell line MCF10A have a high baseline twist, and we identify factors that both increase and decrease this twist. The midzone motors KIF4A and MKLP1 are together required for left-handed twist at anaphase, and we show that KIF4A generates left-handed torque in vitro. The actin cytoskeleton also contributes to left-handed twist, but dynein and its cortical recruitment factor LGN counteract it. Together, our work demonstrates that force generators regulate twist in opposite directions from both within and outside the spindle, preventing strong spindle twist during chromosome segregation.


Assuntos
Anáfase , Cinesinas , Microtúbulos , Fuso Acromático , Humanos , Fuso Acromático/metabolismo , Cinesinas/metabolismo , Cinesinas/genética , Microtúbulos/metabolismo , Dineínas/metabolismo , Dineínas/genética , Torque , Segregação de Cromossomos , Citoesqueleto de Actina/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Associadas aos Microtúbulos/genética
20.
J Cell Biol ; 223(9)2024 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-38913324

RESUMO

Here, we report the generation of a transgenic Lifeact-EGFP quail line for the investigation of actin organization and dynamics during morphogenesis in vivo. This transgenic avian line allows for the high-resolution visualization of actin structures within the living embryo, from the subcellular filaments that guide cell shape to the supracellular assemblies that coordinate movements across tissues. The unique suitability of avian embryos to live imaging facilitates the investigation of previously intractable processes during embryogenesis. Using high-resolution live imaging approaches, we present the dynamic behaviors and morphologies of cellular protrusions in different tissue contexts. Furthermore, through the integration of live imaging with computational segmentation, we visualize cells undergoing apical constriction and large-scale actin structures such as multicellular rosettes within the neuroepithelium. These findings not only enhance our understanding of tissue morphogenesis but also demonstrate the utility of the Lifeact-EGFP transgenic quail as a new model system for live in vivo investigations of the actin cytoskeleton.


Assuntos
Citoesqueleto de Actina , Actinas , Animais Geneticamente Modificados , Proteínas de Fluorescência Verde , Codorniz , Animais , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Fluorescência Verde/genética , Actinas/metabolismo , Actinas/genética , Citoesqueleto de Actina/metabolismo , Morfogênese , Embrião não Mamífero/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...