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1.
Mol Cancer ; 22(1): 21, 2023 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-36721170

RESUMO

BACKGROUND: Excessive extracellular matrix deposition and increased stiffness are typical features of solid tumors such as hepatocellular carcinoma (HCC) and pancreatic ductal adenocarcinoma (PDAC). These conditions create confined spaces for tumor cell migration and metastasis. The regulatory mechanism of confined migration remains unclear. METHODS: LC-MS was applied to determine the differentially expressed proteins between HCC tissues and corresponding adjacent tissue. Collective migration and single cell migration microfluidic devices with 6 µm-high confined channels were designed and fabricated to mimic the in vivo confined space. 3D invasion assay was created by Matrigel and Collagen I mixture treat to adherent cells. 3D spheroid formation under various stiffness environment was developed by different substitution percentage GelMA. Immunoprecipitation was performed to pull down the LH1-binding proteins, which were identified by LC-MS. Immunofluorescent staining, FRET, RT-PCR, Western blotting, FRAP, CCK-8, transwell cell migration, wound healing, orthotopic liver injection mouse model and in vivo imaging were used to evaluate the target expression and cellular phenotype. RESULTS: Lysyl hydroxylase 1 (LH1) promoted the confined migration of cancer cells at both collective and single cell levels. In addition, LH1 enhanced cell invasion in a 3D biomimetic model and spheroid formation in stiffer environments. High LH1 expression correlated with poor prognosis of both HCC and PDAC patients, while it also promoted in vivo metastasis. Mechanistically, LH1 bound and stabilized Septin2 (SEPT2) to enhance actin polymerization, depending on the hydroxylase domain. Finally, the subpopulation with high expression of both LH1 and SEPT2 had the poorest prognosis. CONCLUSIONS: LH1 promotes the confined migration and metastasis of cancer cells by stabilizing SEPT2 and thus facilitating actin polymerization.


Assuntos
Carcinoma Hepatocelular , Carcinoma Ductal Pancreático , Neoplasias Hepáticas , Neoplasias Pancreáticas , Animais , Camundongos , Actinas , Carcinoma Hepatocelular/genética , Carcinoma Ductal Pancreático/genética , Neoplasias Hepáticas/genética , Neoplasias Pancreáticas/genética , Pró-Colágeno-Lisina 2-Oxoglutarato 5-Dioxigenase/genética , Septinas
2.
Zhongguo Zhong Yao Za Zhi ; 48(2): 390-398, 2023 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-36725229

RESUMO

This study aimed to investigate the effects of nanoparticles PLGA-NPs and mesoporous silicon nanoparticles(MSNs) of different stiffness before and after combination with menthol or curcumol on the mechanical properties of bEnd.3 cells. The particle size distributions of PLGA-NPs and MSNs were measured by Malvern particle size analyzer, and the stiffness of the two nanoparticles was quantified by atomic force microscopy(AFM). The bEnd.3 cells were cultured in vitro, and the cell surface morphology, roughness, and Young's modulus were examined to characterize the roughness and stiffness of the cell surface. The changes in the mechanical properties of the cells were observed by AFM, and the structure and expression of cytoskeletal F-actin were observed by a laser-scanning confocal microscope. The results showed that both nanoparticles had good dispersion. The particle size of PLGA-NPs was(98.77±2.04) nm, the PDI was(0.140±0.030), and Young's modulus value was(104.717±8.475) MPa. The particle size of MSNs was(97.47±3.92) nm, the PDI was(0.380±0.016), and Young's modulus value was(306.019±8.822) MPa. The stiffness of PLGA-NPs was significantly lower than that of MSNs. After bEnd.3 cells were treated by PLGA-NPs and MSNs separately, the cells showed fine pores on the cell surface, increased roughness, decreased Young's modulus, blurred and broken F-actin bands, and reduced mean gray value. Compared with PLGA-NPs alone, PLGA-NPs combined with menthol or curcumol could allow deepened and densely distributed surface pores of bEnd.3 cells, increase roughness, reduce Young's modulus, aggravate F-actin band breakage, and diminish mean gray value. Compared with MSNs alone, MSNs combined with menthol could allow deepened and densely distributed surface pores of bEnd.3 cells, increase roughness, reduce Young's modulus, aggravate F-actin band breakage, and diminish mean gray value, while no significant difference was observed in combination with curcumol. Therefore, it is inferred that the aromatic components can increase the intracellular uptake and transport of nanoparticles by altering the biomechanical properties of bEnd.3 cells.


Assuntos
Mentol , Nanopartículas , Animais , Camundongos , Mentol/farmacologia , Actinas/metabolismo , Células Endoteliais/metabolismo , Nanopartículas/química
3.
Braz J Med Biol Res ; 56: e12279, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36722658

RESUMO

Gelsolin (GSN) can sever actin filaments associated with autophagy. This study investigated how GSN-regulated actin filaments control autophagy in pancreatic ductal epithelial cells (PDECs) in acute pancreatitis (AP). AP was produced in a rat model and PDECs using caerulein (CAE). Rat pancreatic duct tissue and HPDE6-C7 cells were extracted at 6, 12, 24, and 48 h after CAE treatment. HPDE6-C7 cells in the presence of CAE were treated with cytochalasin B (CB) or silenced for GSN for 24 h. Pancreatic histopathology and serum amylase levels were analyzed. Cellular ultrastructure and autophagy in PDECs were observed by transmission electron microscopy after 24 h of CAE treatment. The expression of GSN and autophagy markers LC3, P62, and LAMP2 was evaluated in PDECs by immunohistochemistry and western blotting. Actin filaments were observed microscopically. Amylase levels were highest at 6 h of AP, and pancreatic tissue damage increased over time. Mitochondrial vacuolization and autophagy were observed in PDECs. CAE increased GSN expression in these cells over time, increased the LC3-II/LC3-I ratio and LAMP2 expression at 24 and 6 h of treatment, respectively, and decreased P62 expression at all time points. CB treatment for 24 h decreased the LC3-II/LC3-I ratio and LAMP2 expression, increased P62 levels, but had no impact on GSN expression in CAE-treated PDECs. CAE induced actin depolymerization, and CB potentiated this effect. GSN silencing increased the LC3-II/LC3-I ratio and LAMP2 expression and reduced actin depolymerization in CAE-treated PDECs. GSN may inhibit autophagosome biogenesis and autophagosome-lysosome fusion by increasing actin depolymerization in PDECs in AP.


Assuntos
Pancreatite , Animais , Ratos , Gelsolina , Actinas , Doença Aguda , Autofagia , Células Epiteliais , Ductos Pancreáticos , Amilases
4.
BMC Biol ; 21(1): 13, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36721160

RESUMO

BACKGROUND: Folates are crucial for the biosynthesis of nucleotides and amino acids, essential for cell proliferation and development. Folate deficiency induces DNA damage, developmental defects, and tumorigenicity. The obligatory enzyme folylpolyglutamate synthetase (FPGS) mediates intracellular folate retention via cytosolic and mitochondrial folate polyglutamylation. Our previous paper demonstrated the association of the cytosolic FPGS (cFPGS) with the cytoskeleton and various cell protrusion proteins. Based on these recent findings, the aim of the current study was to investigate the potential role of cFPGS at cell protrusions. RESULTS: Here we uncovered a central role for two G-quadruplex (GQ) motifs in the 3'UTR of FPGS mediating the localization of cFPGS mRNA and protein at cell protrusions. Using the MBSV6-loop reporter system and fluorescence microscopy, we demonstrate that following folate deprivation, cFPGS mRNA is retained in the endoplasmic reticulum, whereas upon 15 min of folate repletion, this mRNA is rapidly translocated to cell protrusions in a 3'UTR- and actin-dependent manner. The actin dependency of this folate-induced mRNA translocation is shown by treatment with Latrunculin B and inhibitors of the Ras homolog family member A (RhoA) pathway. Upon folate repletion, the FPGS 3'UTR GQs induce an amoeboid/mesenchymal hybrid cell phenotype during migration and invasion through a collagen gel matrix. Targeted disruption of the 3'UTR GQ motifs by introducing point mutations or masking them by antisense oligonucleotides abrogated cell protrusion targeting of cFPGS mRNA. CONCLUSIONS: Collectively, the GQ motifs within the 3'UTR of FPGS regulate its transcript and protein localization at cell protrusions in response to a folate cue, inducing cancer cell invasive phenotype. These novel findings suggest that the 3'UTR GQ motifs of FPGS constitute an attractive druggable target aimed at inhibition of cancer invasion and metastasis.


Assuntos
Quadruplex G , Neoplasias , Humanos , Ácido Fólico , Regiões 3' não Traduzidas , Actinas
5.
Cell Mol Biol Lett ; 28(1): 7, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36694134

RESUMO

BACKGROUND: Mechanotransduction mechanisms whereby periodontal ligament stem cells (PDLSCs) translate mechanical stress into biochemical signals and thereby trigger osteogenic programs necessary for alveolar bone remodeling are being deciphered. Low-density lipoprotein receptor-related protein 6 (LRP6), a Wnt transmembrane receptor, has been qualified as a key monitor for mechanical cues. However, the role of LRP6 in the mechanotransduction of mechanically induced PDLSCs remains obscure. METHODS: The Tension System and tooth movement model were established to determine the expression profile of LRP6. The loss-of-function assay was used to investigate the role of LRP6 on force-regulated osteogenic commitment in PDLSCs. The ability of osteogenic differentiation and proliferation was estimated by alkaline phosphatase (ALP) staining, ALP activity assay, western blotting, quantitative real-time PCR (qRT-PCR), and immunofluorescence. Crystalline violet staining was used to visualize cell morphological change. Western blotting, qRT-PCR, and phalloidin staining were adopted to affirm filamentous actin (F-actin) alteration. YAP nucleoplasmic localization was assessed by immunofluorescence and western blotting. YAP transcriptional response was evaluated by qRT-PCR. Cytochalasin D was used to determine the effects of F-actin on osteogenic commitment and YAP switch behavior in mechanically induced PDLSCs. RESULTS: LRP6 was robustly activated in mechanically induced PDLSCs and PDL tissues. LRP6 deficiency impeded force-dependent osteogenic differentiation and proliferation in PDLSCs. Intriguingly, LRP6 loss caused cell morphological aberration, F-actin dynamics disruption, YAP nucleoplasmic relocation, and subsequent YAP inactivation. Moreover, disrupted F-actin dynamics inhibited osteogenic differentiation, proliferation, YAP nuclear translocation, and YAP activation in mechanically induced PDLSCs. CONCLUSIONS: We identified that LRP6 in PDLSCs acted as the mechanosensor regulating mechanical stress-inducible osteogenic commitment via the F-actin/YAP cascade. Targeting LRP6 for controlling alveolar bone remodeling may be a prospective therapy to attenuate relapse of orthodontic treatment.


Assuntos
Actinas , Proteína-6 Relacionada a Receptor de Lipoproteína de Baixa Densidade , Osteogênese , Ligamento Periodontal , Células-Tronco , Actinas/genética , Actinas/metabolismo , Diferenciação Celular/fisiologia , Proliferação de Células , Células Cultivadas , Proteína-6 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Proteína-6 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Mecanotransdução Celular/genética , Mecanotransdução Celular/fisiologia , Osteogênese/genética , Osteogênese/fisiologia , Ligamento Periodontal/citologia , Ligamento Periodontal/metabolismo , Células-Tronco/metabolismo
6.
Phytomedicine ; 109: 154573, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36610128

RESUMO

BACKGROUND: Beauvericin (BEA) is a depsipeptide with antimicrobial, anti-inflammatory, and anti-cancer activities isolated from Beauveria bassiana. However, little is understood on its anti-cancer activities and mechanism. PURPOSE: Aim of this study was to explore the anti-cancer activity of BEA and its underlying molecular mechanism to provide a theoretical basis for its role as a candidate natural drug in cancer diseases. STUDY DESIGN: Various cancer cells such as C6 glioma, U251, MDA-MB-231, HeLa, HCT-15, LoVo cells, and HEK293T cells were used to the anti-cancer activity of BEA. METHODS: To evaluate the anti-cancer activity of BEA, cell viability test (MTT assay), morphological change check, confocal microscopy, actin polymerization assay, flow cytometry, and Western blotting analysis. To check the target enzyme of BEA, overexpression and site-directed mutagenesis was employed. RESULTS: BEA inhibited the viability of cancer cells including C6, MDA-MB-231, HeLa, HCT-15, LoVo, and U251 cells. Treatment of BEA in C6 glioma cells induced cell membrane blebbing and apoptosis. Caspase-3 and -9 were dose-dependently activated by BEA, and the mRNA expression of Bcl-2 was inhibited by BEA. According to confocal microscopy, actin polymerization and actin-actin interaction were interrupted by BEA in C6 cells. BEA regulated the apoptosis of C6 cells depending on the protein phosphorylation of Src and Signal transducer and activator of transcription (STAT3). Moreover, c-terminal amino acids in Src directly interacted with BEA in C6 cells, and the binding of Src and BEA suppressed the kinase activity of Src. CONCLUSIONS: These results suggest that BEA may be a critical candidate or substitute drug for cancer treatment via suppression of the Src/STAT3 pathway.


Assuntos
Actinas , Antineoplásicos , Depsipeptídeos , Neoplasias , Humanos , Actinas/metabolismo , Apoptose , Linhagem Celular Tumoral , Depsipeptídeos/farmacologia , Células HEK293 , Fosforilação , Polimerização , Fator de Transcrição STAT3/metabolismo , Antineoplásicos/farmacologia , Neoplasias/tratamento farmacológico
7.
Dev Cell ; 58(1): 18-33.e6, 2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36626869

RESUMO

Actin-based protrusions extend from the surface of all eukaryotic cells, where they support diverse activities essential for life. Models of protrusion growth hypothesize that actin filament assembly exerts force for pushing the plasma membrane outward. However, membrane-associated myosin motors are also abundant in protrusions, although their potential for contributing, growth-promoting force remains unexplored. Using an inducible system that docks myosin motor domains to membrane-binding modules with temporal control, we found that application of myosin-generated force to the membrane is sufficient for driving robust protrusion elongation in human, mouse, and pig cell culture models. Protrusion growth scaled with motor accumulation, required barbed-end-directed force, and was independent of cargo delivery or recruitment of canonical elongation factors. Application of growth-promoting force was also supported by structurally distinct myosin motors and membrane-binding modules. Thus, myosin-generated force can drive protrusion growth, and this mechanism is likely active in diverse biological contexts.


Assuntos
Actinas , Miosinas , Camundongos , Animais , Humanos , Suínos , Miosinas/metabolismo , Actinas/metabolismo , Citoesqueleto de Actina/metabolismo , Membrana Celular/metabolismo , Membranas/metabolismo
8.
Proc Natl Acad Sci U S A ; 120(2): e2217437120, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36598940

RESUMO

Sheet-like membrane protrusions at the leading edge, termed lamellipodia, drive 2D-cell migration using active actin polymerization. Microspikes comprise actin-filament bundles embedded within lamellipodia, but the molecular mechanisms driving their formation and their potential functional relevance have remained elusive. Microspike formation requires the specific activity of clustered Ena/VASP proteins at their tips to enable processive actin assembly in the presence of capping protein, but the factors and mechanisms mediating Ena/VASP clustering are poorly understood. Systematic analyses of B16-F1 melanoma mutants lacking potential candidate proteins revealed that neither inverse BAR-domain proteins, nor lamellipodin or Abi is essential for clustering, although they differentially contribute to lamellipodial VASP accumulation. In contrast, unconventional myosin-X (MyoX) identified here as proximal to VASP was obligatory for Ena/VASP clustering and microspike formation. Interestingly, and despite the invariable distribution of other relevant marker proteins, the width of lamellipodia in MyoX-KO mutants was significantly reduced as compared with B16-F1 control, suggesting that microspikes contribute to lamellipodium stability. Consistently, MyoX removal caused marked defects in protrusion and random 2D-cell migration. Strikingly, Ena/VASP-deficiency also uncoupled MyoX cluster dynamics from actin assembly in lamellipodia, establishing their tight functional association in microspike formation.


Assuntos
Actinas , Sinapsinas , Camundongos , Actinas/metabolismo , Movimento Celular , Miosinas/genética , Miosinas/metabolismo , Fosfoproteínas/metabolismo , Pseudópodes/metabolismo , Sinapsinas/metabolismo , Animais , Linhagem Celular Tumoral
9.
J Cell Biol ; 222(3)2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-36607273

RESUMO

Plastin 3 (PLS3) is an F-actin-bundling protein that has gained attention as a modifier of spinal muscular atrophy (SMA) pathology. SMA is a lethal pediatric neuromuscular disease caused by loss of or mutations in the Survival Motor Neuron 1 (SMN1) gene. Pathophysiological hallmarks are cellular maturation defects of motoneurons prior to degeneration. Despite the observed beneficial modifying effect of PLS3, the mechanism of how it supports F-actin-mediated cellular processes in motoneurons is not yet well understood. Our data reveal disturbed F-actin-dependent translocation of the Tropomyosin receptor kinase B (TrkB) to the cell surface of Smn-deficient motor axon terminals, resulting in reduced TrkB activation by its ligand brain-derived neurotrophic factor (BDNF). Improved actin dynamics by overexpression of hPLS3 restores membrane recruitment and activation of TrkB and enhances spontaneous calcium transients by increasing Cav2.1/2 "cluster-like" formations in SMA axon terminals. Thus, our study provides a novel role for PLS3 in supporting correct alignment of transmembrane proteins, a key mechanism for (moto)-neuronal development.


Assuntos
Actinas , Proteínas de Membrana , Proteínas dos Microfilamentos , Atrofia Muscular Espinal , Receptor trkB , Humanos , Actinas/metabolismo , Proteínas de Transporte/metabolismo , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Neurônios Motores/metabolismo , Atrofia Muscular Espinal/genética , Atrofia Muscular Espinal/patologia , Proteína 1 de Sobrevivência do Neurônio Motor/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Receptor trkB/metabolismo
10.
Nat Commun ; 14(1): 96, 2023 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-36609407

RESUMO

Gated entry of lipophilic ligands into the enclosed hydrophobic pocket in stand-alone Sec14 domain proteins often links lipid metabolism to membrane trafficking. Similar domains occur in multidomain mammalian proteins that activate small GTPases and regulate actin dynamics. The neuronal RhoGEF Kalirin, a central regulator of cytoskeletal dynamics, contains a Sec14 domain (KalbSec14) followed by multiple spectrin-like repeats and catalytic domains. Previous studies demonstrated that Kalirin lacking its Sec14 domain fails to maintain cell morphology or dendritic spine length, yet whether and how KalbSec14 interacts with lipids remain unknown. Here, we report the structural and biochemical characterization of KalbSec14. KalbSec14 adopts a closed conformation, sealing off the canonical ligand entry site, and instead employs a surface groove to bind a limited set of lysophospholipids. The low-affinity interactions of KalbSec14 with lysolipids are expected to serve as a general model for the regulation of Rho signaling by other Sec14-containing Rho activators.


Assuntos
Actinas , Citoesqueleto , Animais , Fatores de Troca de Nucleotídeo Guanina Rho/genética , Lipídeos , Mamíferos
11.
In Vivo ; 37(1): 242-246, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36593027

RESUMO

BACKGROUND/AIM: Surface biomarkers, such as CD44 and CD133, have been demonstrated to be expressed in prostate cancer cells, and our previous study has shown that prostate cancer cell lines could be divided into three groups according to the single and combined expression pattern of CD44 and 133. In order to refine prognostication in prostate cancer cells, we further investigated genetic biomarkers, prostate cancer antigen 3 (PCA3), kallikrein 4 (KLK4), and KLK9 in different prostate cancer cell lines. MATERIALS AND METHODS: CWR22Rv1, PC3, and DU145 cell lines were cultured until 95% confluence. The single expression of CD44 or CD133 and their combined expression were analyzed by flow cytometry, and gene expression of b-actin, PCA3, KLK4, and KLK9 was analyzed by real-time polymerase chain reaction. RESULTS: The single expression of CD133 was less than 4% in all cell lines examined. PC3 and DU145 cells displayed a high expression of CD44 (>91%), whereas CWR22Rv1 was the only cell line that demonstrated a high co-expression of both CD44 and CD133 (>91%). In addition, PC3 and DU145 displayed low expression of PCA3, KLK4, and KLK9 when compared with their own b-actin expression. In contrast, CWR22Rva showed high expression of PCA3 and KLK4 although KLK9 expression was also low. CONCLUSION: Both surface and genetic biomarkers should be validated for a more accurate prognosis in prostate cancer.


Assuntos
Actinas , Neoplasias da Próstata , Masculino , Humanos , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Linhagem Celular , Próstata
12.
Int J Mol Sci ; 24(2)2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36674829

RESUMO

Dent disease (DD1) is a rare tubulopathy caused by mutations in the CLCN5 gene. Glomerulosclerosis was recently reported in DD1 patients and ClC-5 protein was shown to be expressed in human podocytes. Nephrin and actin cytoskeleton play a key role for podocyte functions and podocyte endocytosis seems to be crucial for slit diaphragm regulation. The aim of this study was to analyze whether ClC-5 loss in podocytes might be a direct consequence of the glomerular damage in DD1 patients. Three DD1 kidney biopsies presenting focal global glomerulosclerosis and four control biopsies were analyzed by immunofluorescence (IF) for nephrin and podocalyxin, and by immunohistochemistry (IHC) for ClC-5. ClC-5 resulted as down-regulated in DD1 vs. control (CTRL) biopsies in both tubular and glomerular compartments (p < 0.01). A significant down-regulation of nephrin (p < 0.01) in DD1 vs. CTRL was demonstrated. CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/Caspase9) gene editing of CLCN5 in conditionally immortalized human podocytes was used to obtain clones with the stop codon mutation p.(R34Efs*14). We showed that ClC-5 and nephrin expression, analyzed by quantitative Reverse Transcription/Polymerase Chain Reaction (qRT/PCR) and In-Cell Western (ICW), was significantly downregulated in mutant clones compared to the wild type ones. In addition, F-actin staining with fluorescent phalloidin revealed actin derangements. Our results indicate that ClC-5 loss might alter podocyte function either through cytoskeleton disorganization or through impairment of nephrin recycling.


Assuntos
Canais de Cloreto , Doença de Dent , Glomerulosclerose Segmentar e Focal , Podócitos , Humanos , Actinas/genética , Actinas/metabolismo , Doença de Dent/genética , Doença de Dent/patologia , Glomerulosclerose Segmentar e Focal/metabolismo , Glomérulos Renais/metabolismo , Podócitos/metabolismo , Canais de Cloreto/metabolismo
13.
Genome Biol ; 24(1): 18, 2023 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-36698204

RESUMO

BACKGROUND: Recent work has demonstrated that three-dimensional genome organization is directly affected by changes in the levels of nuclear cytoskeletal proteins such as ß-actin. The mechanisms which translate changes in 3D genome structure into changes in transcription, however, are not fully understood. Here, we use a comprehensive genomic analysis of cells lacking nuclear ß-actin to investigate the mechanistic links between compartment organization, enhancer activity, and gene expression. RESULTS: Using HiC-Seq, ATAC-Seq, and RNA-Seq, we first demonstrate that transcriptional and chromatin accessibility changes observed upon ß-actin loss are highly enriched in compartment-switching regions. Accessibility changes within compartment switching genes, however, are mainly observed in non-promoter regions which potentially represent distal regulatory elements. Our results also show that ß-actin loss induces widespread accumulation of the enhancer-specific epigenetic mark H3K27ac. Using the ABC model of enhancer annotation, we then establish that these epigenetic changes have a direct impact on enhancer activity and underlie transcriptional changes observed upon compartment switching. A complementary analysis of fibroblasts undergoing reprogramming into pluripotent stem cells further confirms that this relationship between compartment switching and enhancer-dependent transcriptional change is not specific to ß-actin knockout cells but represents a general mechanism linking compartment-level genome organization to gene expression. CONCLUSIONS: We demonstrate that enhancer-dependent transcriptional regulation plays a crucial role in driving gene expression changes observed upon compartment-switching. Our results also reveal a novel function of nuclear ß-actin in regulating enhancer function by influencing H3K27 acetylation levels.


Assuntos
Actinas , Regulação da Expressão Gênica , Actinas/metabolismo , Sequências Reguladoras de Ácido Nucleico , Epigênese Genética , Genoma , Elementos Facilitadores Genéticos , Cromatina
14.
Anal Chem ; 95(4): 2329-2338, 2023 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-36638208

RESUMO

Recently, a novel technology was published, utilizing the strengths of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) and immunohistochemistry (IHC), achieving highly multiplexed, targeted imaging of biomolecules in tissue. This new technique, called MALDI-IHC, opened up workflows to target molecules of interest using MALDI-MSI that are usually targeted by standard IHC. In this paper, the utility of targeted MALDI-IHC and its complementarity with untargeted on-tissue bottom-up spatial proteomics is explored using breast cancer tissue. Furthermore, the MALDI-2 effect was investigated and demonstrated to improve MALDI-IHC. Formalin-fixed paraffin-embedded (FFPE) human breast cancer tissue sections were stained for multiplex MALDI-IHC with six photocleavable mass-tagged (PC-MT) antibodies constituting a breast cancer antibody panel (CD20, actin-αSM, HER2, CD68, vimentin, and panCK). K-means spatial clusters were created based on the MALDI-IHC images and cut out using laser-capture microdissection (LMD) for further untargeted LC-MS-based bottom-up proteomics analyses. Numerous peptides could be tentatively assigned to multiple proteins, of which three proteins were also part of the antibody panel (vimentin, keratins, and actin). Post-ionization with MALDI-2 showed an increased intensity of the PC-MTs and suggests options for the development of new mass-tags. Although the on-tissue digestion covered a wider range of proteins, the MALDI-IHC allowed for easy and straightforward identification of proteins that were not detected in untargeted approaches. The combination of the multiplexed MALDI-IHC with image-guided proteomics showed great potential to further investigate diseases by providing complementary information from the same tissue section and without the need for customized instrumentation.


Assuntos
Neoplasias da Mama , Proteômica , Humanos , Feminino , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Vimentina , Proteômica/métodos , Imuno-Histoquímica , Actinas , Imagem Molecular
15.
Sci Rep ; 13(1): 909, 2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36650375

RESUMO

Small blood vessel diseases are often associated with impaired regulation of vascular tone. The current understanding of resistance arteries often focuses on how a level of vascular tone is achieved in the acute phase, while less emphasis is placed on mechanisms that maintain vascular tone. In this study, cannulated rat superior cerebellar arteries (SCA) developed spontaneous myogenic tone and showed a marked and sustained constriction in the presence of diluted serum (10%), a stimulus relevant to cerebrovascular disease. Both phosphorylated myosin light chain (MLC-p) and smooth muscle alpha actin (SM-α-actin) aligned with phalloidin-stained actin filaments in the vessel wall, while exhibiting a 'high to low' gradient across the layers of vascular smooth muscle cells (VSMC), peaking in the outer layer. The MLC-p distribution profile shifted towards the adventitia in serum treated vessels, while removal of the serum reversed it. Furthermore, a positive correlation between the MLC-p signal and vessel wall tension was also evident. The gradients of phosphorylated MLC and SM-α-actin are consistent with a spatial regulation of the myosin-actin apparatus in the vessel wall during the maintenance of vascular tone. Further, the changing profiles of MLC-p and SM-α-actin are consistent with SCA vasoconstriction being accompanied by VSMC cytoskeletal reorganization.


Assuntos
Actinas , Cadeias Leves de Miosina , Ratos , Animais , Cadeias Leves de Miosina/metabolismo , Actinas/metabolismo , Músculo Liso Vascular/metabolismo , Fosforilação , Artérias Cerebrais/metabolismo , Vasoconstrição/fisiologia
16.
Biomater Adv ; 145: 213277, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36621197

RESUMO

Cells are not only anchored to the extracellular matrix via the focal adhesion complex, the focal adhesion complex also serves as a sensor for force transduction. How tension influences the structure of focal adhesions is not well understood. Here, we analyse the effect of tension on the location of key focal adhesion proteins, namely vinculin, paxillin and actin. We use micropatterning on gold surfaces to manipulate the cell shape, to create focal adhesions at specific cell areas, and to perform metal-induced energy transfer (MIET) measurements on the patterned cells. MIET resolves the different protein locations with respect to the gold surface with nanometer accuracy. Further, we use drugs influencing the cellular motor protein myosin or mechanosensitive ion channels to get deeper insight into focal adhesions at different tension states. We show here that in particular actin is affected by the rationally tuned force balance. Blocking mechanosensitive ion channels has a particularly high influence on the actin and focal adhesion architecture, resulting in larger focal adhesions with elevated paxillin and vinculin and strongly lowered actin stress fibres. Our results can be explained by a balance of adhesion tension with cellular tension together with ion channel-controlled focal adhesion homeostasis, where high cellular tension leads to an elevation of vinculin and actin, while high adhesion tension lowers these proteins.


Assuntos
Actinas , Adesões Focais , Adesões Focais/metabolismo , Actinas/metabolismo , Paxilina/metabolismo , Citoesqueleto/metabolismo , Vinculina/metabolismo , Forma Celular
17.
J Gen Physiol ; 155(3)2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-36633586

RESUMO

Following binding to the thin filament, ß-cardiac myosin couples ATP-hydrolysis to conformational rearrangements in the myosin motor that drive myofilament sliding and cardiac ventricular contraction. However, key features of the cardiac-specific actin-myosin interaction remain uncertain, including the structural effect of ADP release from myosin, which is rate-limiting during force generation. In fact, ADP release slows under experimental load or in the intact heart due to the afterload, thereby adjusting cardiac muscle power output to meet physiological demands. To further elucidate the structural basis of this fundamental process, we used a combination of cryo-EM reconstruction methodologies to determine structures of the human cardiac actin-myosin-tropomyosin filament complex at better than 3.4 Å-resolution in the presence and in the absence of Mg2+·ADP. Focused refinements of the myosin motor head and its essential light chains in these reconstructions reveal that small changes in the nucleotide-binding site are coupled to significant rigid body movements of the myosin converter domain and a 16-degree lever arm swing. Our structures provide a mechanistic framework to understand the effect of ADP binding and release on human cardiac ß-myosin, and offer insights into the force-sensing mechanism displayed by the cardiac myosin motor.


Assuntos
Actinas , Tropomiosina , Humanos , Actinas/metabolismo , Tropomiosina/metabolismo , Miosinas Cardíacas/metabolismo , Miosinas/metabolismo , Citoesqueleto de Actina/metabolismo
18.
J Gen Physiol ; 155(3)2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-36633585

RESUMO

Skeletal myosins II are non-processive molecular motors that work in ensembles to produce muscle contraction while binding to the actin filament. Although the molecular properties of myosin II are well known, there is still debate about the collective work of the motors: is there cooperativity between myosin motors while binding to the actin filaments? In this study, we use high-speed AFM to evaluate this issue. We observed that the initial binding of small arrays of myosin heads to the non-regulated actin filaments did not affect the cooperative probability of subsequent bindings and did not lead to an increase in the fractional occupancy of the actin binding sites. These results suggest that myosin motors are independent force generators when connected in small arrays, and that the binding of one myosin does not alter the kinetics of other myosins. In contrast, the probability of binding of myosin heads to regulated thin filaments under activating conditions (at high Ca2+ concentration in the presence of 2 µM ATP) was increased with the initial binding of one myosin, leading to a larger occupancy of available binding sites at the next half-helical pitch of the filament. The result suggests that myosin cooperativity is observed over five pseudo-repeats and defined by the activation status of the thin filaments.


Assuntos
Miosina Tipo II , Miosinas , Miosina Tipo II/análise , Miosina Tipo II/metabolismo , Miosinas/metabolismo , Contração Muscular/fisiologia , Actinas/metabolismo , Citoesqueleto de Actina/metabolismo , Músculo Esquelético/metabolismo
19.
Proc Natl Acad Sci U S A ; 120(4): e2208536120, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36656858

RESUMO

Actin cytoskeleton force generation, sensing, and adaptation are dictated by the bending and twisting mechanics of filaments. Here, we use magnetic tweezers and microfluidics to twist and pull individual actin filaments and evaluate their response to applied loads. Twisted filaments bend and dissipate torsional strain by adopting a supercoiled plectoneme. Pulling prevents plectoneme formation, which causes twisted filaments to sever. Analysis over a range of twisting and pulling forces and direct visualization of filament and single subunit twisting fluctuations yield an actin filament torsional persistence length of ~10 µm, similar to the bending persistence length. Filament severing by cofilin is driven by local twist strain at boundaries between bare and decorated segments and is accelerated by low pN pulling forces. This work explains how contractile forces generated by myosin motors accelerate filament severing by cofilin and establishes a role for filament twisting in the regulation of actin filament stability and assembly dynamics.


Assuntos
Citoesqueleto de Actina , Citoesqueleto , Citoesqueleto de Actina/metabolismo , Citoesqueleto/metabolismo , Fatores de Despolimerização de Actina/metabolismo , Miosinas/metabolismo , Ligação Proteica , Actinas/metabolismo
20.
Curr Protoc ; 3(1): e655, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36689324

RESUMO

Fluorescence recovery after photobleaching (FRAP) is widely used to evaluate intracellular molecular turnover or repeated translocation of molecules using confocal laser scanning microscopy. While numerous models have been developed for the analysis of FRAP responses, in which chemical interactions and/or fast diffusion processes are involved, it is inherently difficult to evaluate the long-term behavior of molecular turnover because of the presence of intracellular flow and microscopic deformation of bleached regions. To overcome these difficulties, we have developed a novel continuum mechanics-based FRAP (CM-FRAP) approach that enables simultaneous evaluation of long-term molecular turnover and intracellular flow/deformation. Here we demonstrate the utility of CM-FRAP by using actin molecules associated with stress fibers in rat aortic smooth muscle cells with clarification of the experimental setup and data analysis. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Plasmid construction and sample preparation Basic Protocol 2: How to perform FRAP experiments Basic Protocol 3: Data analysis based on CM-FRAP.


Assuntos
Actinas , Animais , Ratos , Recuperação de Fluorescência Após Fotodegradação/métodos , Microscopia Confocal/métodos , Fotodegradação , Difusão
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