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1.
J Exp Clin Cancer Res ; 41(1): 28, 2022 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-35045880

RESUMO

BACKGROUND: Estrogen-related receptor α (ERRα) has been reported to play a critical role in endometrial cancer (EC) progression. However, the underlying mechanism of ERRα-mediated lipid reprogramming in EC remains elusive. The transcription factor EB (TFEB)-ERRα axis induces lipid reprogramming to promote progression of EC was explored in this study. METHODS: TFEB and ERRα were analyzed and validated by RNA-sequencing data from the Cancer Genome Atlas (TCGA). The TFEB-ERRα axis was assessed by dual-luciferase reporter and chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR). The mechanism was investigated using loss-of-function and gain-of-function assays in vitro. Lipidomics and proteomics were performed to identify the TFEB-ERRα-related lipid metabolism pathway. Pseudopods were observed by scanning electron microscope. Furthermore, immunohistochemistry and lipidomics were performed in clinical tissue samples to validate the ERRα-related lipids. RESULTS: TFEB and ERRα were highly expressed in EC patients and correlated to EC progression. ERRα is the direct target of TFEB to mediate EC lipid metabolism. TFEB-ERRα axis mainly affected glycerophospholipids (GPs) and significantly elevated the ratio of phosphatidylcholine (PC)/sphingomyelin (SM), which indicated the enhanced membrane fluidity. TFEB-ERRα axis induced the mitochondria specific phosphatidylglycerol (PG) (18:1/22:6) + H increasing. The lipid reprogramming was mainly related to mitochondrial function though combining lipidomics and proteomics. The maximum oxygen consumption rate (OCR), ATP and lipid-related genes acc, fasn, and acadm were found to be positively correlated with TFEB/ERRα. TFEB-ERRα axis enhanced generation of pseudopodia to increase the invasiveness. Mechanistically, our functional assays indicated that TFEB promoted EC cell migration in an ERRα-dependent manner via EMT signaling. Consistent with the in vitro, higher PC (18:1/18:2) + HCOO was found in EC patients, and those with higher TFEB/ERRα had deeper myometrial invasion and lower serum HDL levels. Importantly, PC (18:1/18:2) + HCOO was an independent risk factor positively related to ERRα for lymph node metastasis. CONCLUSION: Lipid reprogramming induced by the TFEB-ERRα axis increases unsaturated fatty acid (UFA)-containing PCs, PG, PC/SM and pseudopodia, which enhance membrane fluidity via EMT signaling to promote EC progression. PG (18:1/22:6) + H induced by TFEB-ERRα axis was involved in tumorigenesis and PC (18:1/18:2) + HCOO was the ERRα-dependent lipid to mediate EC metastasis.


Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Neoplasias do Endométrio/genética , Fluidez de Membrana/fisiologia , Biologia Computacional , Progressão da Doença , Feminino , Humanos
2.
ACS Appl Mater Interfaces ; 13(25): 29936-29948, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-34143617

RESUMO

Alzheimer's disease (AD) is a major cause of dementia characterized by the overexpression of transmembrane amyloid precursor protein and its neurotoxic byproduct amyloid beta (Aß). A small peptide of considerable hydrophobicity, Aß is aggregation prone catalyzed by the presence of cell membranes, among other environmental factors. Accordingly, current AD mitigation strategies often aim at breaking down the Aß-membrane communication, yet no data is available concerning the cohesive interplay of the three key entities of the cell membrane, Aß, and its inhibitor. Using a lipophilic Laurdan dye and confocal fluorescence microscopy, we observed cell membrane perturbation and actin reorganization induced by Aß oligomers but not by Aß monomers or amyloid fibrils. We further revealed recovery of membrane fluidity by ultrasmall MoS2 quantum dots, also shown in this study as a potent inhibitor of Aß amyloid aggregation. Using discrete molecular dynamics simulations, we uncovered the binding of MoS2 and Aß monomers as mediated by hydrophilic interactions between the quantum dots and the peptide N-terminus. In contrast, Aß oligomers and fibrils were surface-coated by the ultrasmall quantum dots in distinct testudo-like, reverse protein-corona formations to prevent their further association with the cell membrane and adverse effects downstream. This study offers a crucial new insight and a viable strategy for regulating the amyloid aggregation and membrane-axis of AD pathology with multifunctional nanomedicine.


Assuntos
Peptídeos beta-Amiloides , Dissulfetos/química , Fluidez de Membrana/fisiologia , Molibdênio/química , Pontos Quânticos/química , 2-Naftilamina/análogos & derivados , 2-Naftilamina/química , Actinas/química , Actinas/metabolismo , Doença de Alzheimer , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/metabolismo , Linhagem Celular Tumoral , Membrana Celular/química , Membrana Celular/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Lauratos/química , Microscopia Confocal , Simulação de Dinâmica Molecular , Nanomedicina
3.
Opt Express ; 29(8): 11976-11986, 2021 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-33984967

RESUMO

The fluidity of the cell membrane is closely related to cancer metastasis/invasion. To test the relationship of membrane fluidity and invasiveness, we first demonstrated that transfection of small RNA miR-92b-3p can significantly increase invasiveness of the small cell lung cancer cell line SHP77. Then optical tweezers were used to measure membrane fluidity. This study employed continuous and step-like stretching methods to examine fluidity changes in SHP77 cell membranes before and after miR-92b-3p transfection. A newly developed physical model was used to derive the effective viscosity and static tension of the cell membrane from relaxation curves obtained via step-like stretching. Experiments showed that invasiveness and fluidity increased significantly after miR-92b-3p transfection. This study paved the way toward a better understanding of cancer cell invasion and membrane mechanical characteristics.


Assuntos
Neoplasias Pulmonares/patologia , Fluidez de Membrana/fisiologia , Pinças Ópticas , Carcinoma de Pequenas Células do Pulmão/patologia , Linhagem Celular Tumoral , Membrana Celular/fisiologia , Vetores Genéticos , Humanos , Lentivirus/genética , Neoplasias Pulmonares/genética , MicroRNAs/genética , Invasividade Neoplásica , Reação em Cadeia da Polimerase em Tempo Real , Carcinoma de Pequenas Células do Pulmão/genética , Transfecção
4.
J Trace Elem Med Biol ; 54: 214-220, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31109615

RESUMO

Zinc has a strong influence on the function of the immune system and is a driving factor for immune cell development. In this regard, studies revealed cell type specific effects of zinc. During zinc deficiency for example, development and activity of myeloid cells seems to be prioritized at the cost of cells from the lymphoid lineage. In T-cells, the altered proliferation was found to be due to zinc's effect on IL-2-induced signaling processes, but in contrast to lymphoid cells, effects of zinc homeostasis on growth-factor-induced signaling in myeloid cells have not been investigated yet. The granulocyte-macrophage colony-stimulating factor (GM-CSF) is one of the major factors inducing monopoiesis. Considering the structural similarities between the GM-CSF receptor and those of the IL-receptor family as well as a similar set of signaling molecules involved, an impact of zinc on the GM-CSF signaling seems to be likely. Therefore, the effect of zinc on GM-CSF-induced signaling molecules was investigated here, using U937 cells as a model myeloid cell line. GM-CSF stimulation significantly increased STAT5 phosphorylation which was prevented completely by pre-incubation with zinc and pyrithione. U937 cells showed a strong pre-activation regarding c-Raf, which was significantly decreased by zinc and pyrithione incubation, independently from GM-CSF stimulation. As current literature was not sufficient to explain the observed effects, we hypothesized an altered receptor-complex assembly. As membrane composition and plasticity, subsumed under the term of membrane fluidity, was found to affect receptor multimerization, the impact of zinc on membrane fluidity was considered as a completely novel approach. Indeed, addition of zinc also decreased GM-CSFR expression on the cell surface and most interestingly altered membrane fluidity. In conclusion, we hypothesize that the incubation with zinc causes an alteration of membrane fluidity that hinders efficient receptor assembly as well as phosphorylation of signal molecules and therefore signal transduction.


Assuntos
Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacologia , Fluidez de Membrana/fisiologia , Células Mieloides/efeitos dos fármacos , Linhagem Celular , Humanos , Células Mieloides/metabolismo , Fosforilação/efeitos dos fármacos , Fator de Transcrição STAT5/metabolismo , Transdução de Sinais/efeitos dos fármacos , Zinco/metabolismo
5.
J BUON ; 24(1): 158-162, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30941965

RESUMO

PURPOSE: The present study explored the potential of microwaves on membrane fluidity changes in diethylnitrosamine (DEN) induced hepatocellular carcinoma (HCC), in vivo. METHODS: Rats were segregated into four groups: normal control, DEN-treated, microwave-treated, DEN+microwave-treated. Brush border membranes (BBM) were isolated from the rats and, using the membrane extrinsic fluorophore pyrene, we assessed the viscosities as well as fluidity parameters. RESULTS: DEN treatment resulted in a significant rise in lipid peroxidation (LPO). Reduced glutathione levels (GSH) and the activities of glutathione reductase (GR), glutathione transferase (GST), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were found to be significantly decreased following DEN treatment. On the other hand, microwave treatment in DEN-treated rats resulted in a significant decrease in the levels of lipid peroxidation but caused a significant rise in the levels of GSH as well in the activities of GR, GST, SOD, CAT and GPx. The results further demonstrated a marked decrease in membrane microviscosity following DEN treatment. On the other hand, a significant increase was observed in the excimer/monomer ratio and fluidity parameter of DEN-treated rats when compared to normal control rats. However, the alterations in membrane microviscosity and the fluidity parameters were significantly restored after microwave treatment. CONCLUSION: The study, therefore, concludes that microwave proved quite useful in the modulation of membrane stability parameters following DEN-induced hepatic cancer.


Assuntos
Membrana Celular/fisiologia , Dietilnitrosamina/toxicidade , Neoplasias Hepáticas/prevenção & controle , Fluidez de Membrana/fisiologia , Micro-Ondas/uso terapêutico , Alquilantes/toxicidade , Animais , Catalase/metabolismo , Membrana Celular/efeitos dos fármacos , Membrana Celular/efeitos da radiação , Glutationa/metabolismo , Glutationa Redutase/metabolismo , Glutationa Transferase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Neoplasias Hepáticas/induzido quimicamente , Neoplasias Hepáticas/metabolismo , Masculino , Fluidez de Membrana/efeitos dos fármacos , Fluidez de Membrana/efeitos da radiação , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo
6.
Bull Math Biol ; 81(4): 1238-1259, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30607880

RESUMO

A two-dimensional model for red blood cell motion is adapted to consider the dynamics of breast cancer cells in a microfluidic channel. Adjusting parameters to make the membrane stiffer, as is the case with breast cancer cells compared with red blood cells, allows the model to produce reasonable estimates of breast cancer cell trajectories through the channel. In addition, the model produces estimates of quantities not as easily obtained from experiment such as velocity and stress field information throughout the fluid and on the cell membrane. This includes locations of maximum stress along the membrane wall. A sensitivity analysis shows that the model is capable of producing useful insights into various systems involving breast cancer cells. Current results suggest that dynamics taking place when cells are near other objects are most sensitive to membrane and cytoplasm elasticity, dynamics taking place when cells are not near other objects are most sensitive to cytoplasm viscosity, and dynamics are significantly affected by low membrane bending elasticity. These results suggest that continued calibration and application of this model can yield useful predictions in other similar systems.


Assuntos
Neoplasias da Mama/patologia , Modelos Biológicos , Neoplasias da Mama/fisiopatologia , Movimento Celular/fisiologia , Simulação por Computador , Elasticidade/fisiologia , Feminino , Análise de Elementos Finitos , Humanos , Conceitos Matemáticos , Mecanotransdução Celular/fisiologia , Fluidez de Membrana/fisiologia , Microfluídica , Invasividade Neoplásica/patologia , Invasividade Neoplásica/fisiopatologia , Estresse Mecânico , Viscosidade
7.
Traffic ; 18(5): 315-329, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28276191

RESUMO

Diacylglycerol (DAG) is a fusogenic lipid that can be produced through phospholipase C activity on phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2 ], or through phosphatidic acid (PA) phosphatase activity. The fusion of Saccharomyces cerevisiae vacuoles requires DAG, PA and PI(4,5)P2 , and the production of these lipids is thought to provide temporally specific stoichiometries that are critical for each stage of fusion. Furthermore, DAG and PA can be interconverted by the DAG kinase Dgk1 and the PA phosphatase Pah1. Previously we found that pah1 Δ vacuoles were fragmented, blocked in SNARE priming and showed arrested endosomal maturation. In other pathways the effects of deleting PAH1 can be compensated for by additionally deleting DGK1 ; however, deleting both genes did not rescue the pah1 Δ vacuolar defects. Deleting DGK1 alone caused a marked increase in vacuole fusion that was attributed to elevated DAG levels. This was accompanied by a gain in resistance to the inhibitory effects of PA as well as inhibitors of Ypt7 activity. Together these data show that Dgk1 function can act as a negative regulator of vacuole fusion through the production of PA at the cost of depleting DAG and reducing Ypt7 activity.


Assuntos
Diacilglicerol Quinase/metabolismo , Fluidez de Membrana/fisiologia , Proteínas Repressoras/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Endossomos/metabolismo , Fusão de Membrana/fisiologia , Fosfatidato Fosfatase/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Ligação Proteica/fisiologia , Proteínas SNARE/metabolismo , Vacúolos
8.
PLoS Comput Biol ; 13(1): e1005354, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-28135277

RESUMO

Cell polarization toward an attractant is influenced by both physical and chemical factors. Most existing mathematical models are based on reaction-diffusion systems and only focus on the chemical process occurring during cell polarization. However, membrane tension has been shown to act as a long-range inhibitor of cell polarization. Here, we present a cell polarization model incorporating the interplay between Rac GTPase, filamentous actin (F-actin), and cell membrane tension. We further test the predictions of this model by performing single cell measurements of the spontaneous polarization of cancer stem cells (CSCs) and non-stem cancer cells (NSCCs), as the former have lower cell membrane tension. Based on both our model and the experimental results, cell polarization is more sensitive to stimuli under low membrane tension, and high membrane tension improves the robustness and stability of cell polarization such that polarization persists under random perturbations. Furthermore, our simulations are the first to recapitulate the experimental results described by Houk et al., revealing that aspiration (elevation of tension) and release (reduction of tension) result in a decrease in and recovery of the activity of Rac-GTP, respectively, and that the relaxation of tension induces new polarity of the cell body when a cell with the pseudopod-neck-body morphology is severed.


Assuntos
Actinas/metabolismo , Membrana Celular/fisiologia , Polaridade Celular/fisiologia , Mecanotransdução Celular/fisiologia , Modelos Biológicos , Proteínas rac de Ligação ao GTP/metabolismo , Simulação por Computador , Fluidez de Membrana/fisiologia , Estresse Mecânico , Resistência à Tração/fisiologia
9.
J Exp Bot ; 67(17): 5173-85, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27604805

RESUMO

Although plants are exposed to a great number of pathogens, they usually defend themselves by triggering mechanisms able to limit disease development. Alongside signalling events common to most such incompatible interactions, modifications of plasma membrane (PM) physical properties could be new players in the cell transduction cascade. Different pairs of elicitors (cryptogein, oligogalacturonides, and flagellin) and plant cells (tobacco and Arabidopsis) were used to address the issue of possible modifications of plant PM biophysical properties induced by elicitors and their links to other events of the defence signalling cascade. We observed an increase of PM order whatever the elicitor/plant cell pair used, provided that a signalling cascade was induced. Such membrane modification is dependent on the NADPH oxidase-mediated reactive oxygen species production. Moreover, cryptogein, which is the sole elicitor able to trap sterols, is also the only one able to trigger an increase in PM fluidity. The use of cryptogein variants with altered sterol-binding properties confirms the strong correlation between sterol removal from the PM and PM fluidity enhancement. These results propose PM dynamics as a player in early signalling processes triggered by elicitors of plant defence.


Assuntos
Membrana Celular/fisiologia , Resistência à Doença/fisiologia , Fluidez de Membrana/fisiologia , Arabidopsis/fisiologia , Membrana Celular/metabolismo , Microscopia Confocal , Microscopia de Fluorescência , Doenças das Plantas , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/fisiologia , Espectrometria de Fluorescência , Nicotiana/fisiologia
10.
Biochem Biophys Res Commun ; 474(2): 259-263, 2016 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-27079237

RESUMO

The endoplasmic reticulum (ER) is important in various cellular functions, such as secretary and membrane protein biosynthesis, lipid synthesis, and calcium storage. ER stress, including membrane distortion, is associated with many diseases such as Huntington's disease. In particular, nuclear envelope distortion is related to neuronal cell death associated with polyglutamine. However, the mechanism by which polyglutamine causes ER membrane distortion remains unclear. We used electron microscopy, fluorescence protease protection assay, and alkaline treatment to analyze the localization of polyglutamine in cells. We characterized polyglutamine embedded in the ER membrane and noted an effect on morphology, including the dilation of ER luminal space and elongation of ER-mitochondria contact sites, in addition to the distortion of the nuclear envelope. The polyglutamine embedded in the ER membrane was observed at the same time as Bax insertion. These results demonstrated that the ER membrane may be a target of polyglutamine, which triggers cell death through Bax.


Assuntos
Membrana Celular/fisiologia , Membrana Celular/ultraestrutura , Retículo Endoplasmático/fisiologia , Fluidez de Membrana/fisiologia , Peptídeos/metabolismo , Proteína X Associada a bcl-2/metabolismo , Células HEK293 , Humanos
11.
Int J Radiat Biol ; 92(1): 42-9, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26514970

RESUMO

PURPOSE: The effect of extremely low frequency electromagnetic fields (ELF-EMF) on bacteria has attracted attention due to its potential for beneficial uses. This research aimed to determine the effect of ELF-EMF on bacterial membrane namely the membrane potential, surface potential, hydrophobicity, respiratory activity and growth. MATERIALS AND METHODS: Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were subjected to ELF-EMF, 50 Hz, 1 mT for 2 h. Membrane potential was determined by fluorescence spectroscopy with or without EDTA (Ethylenediaminetetraacetic acid) with DisC3(5) (3,3-dipropylthiacarbocyanine iodide), zeta potential measurements were performed by electrophoretic mobility, hydrophobicity of the membrane was measured with MATH (Microbial Adhesion to Hydrocarbons) test, respiratory activity was determined with CTC (5-Cyano-2,3-ditolyl tetrazolium chloride), colony forming unit (CFU) and DAPI (4',6-diamidino-2-phenylindole, dihydrochloride) was used for growth determinations. RESULTS: ELF-EMF caused changes in physicochemical properties of both Gram-positive and Gram-negative bacteria. Hyperpolarization was seen in S. aureus and EDTA-treated E. coli. Surface potential showed a positive shift in S. aureus contrariwise to the negative shift seen in EDTA-untreated E. coli. Respiratory activity increased in both bacteria. A slight decrease in growth was observed. CONCLUSION: These results show that ELF-EMF affects the crucial physicochemical processes in both Gram-positive and Gram-negative bacteria which need further research.


Assuntos
Permeabilidade da Membrana Celular/fisiologia , Membrana Celular/fisiologia , Campos Eletromagnéticos , Escherichia coli/fisiologia , Potenciais da Membrana/fisiologia , Staphylococcus aureus/fisiologia , Membrana Celular/efeitos da radiação , Permeabilidade da Membrana Celular/efeitos da radiação , Relação Dose-Resposta à Radiação , Escherichia coli/efeitos da radiação , Fluidez de Membrana/fisiologia , Fluidez de Membrana/efeitos da radiação , Potenciais da Membrana/efeitos da radiação , Doses de Radiação , Staphylococcus aureus/efeitos da radiação
12.
Neuroscience ; 300: 508-17, 2015 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-26037803

RESUMO

Astrocytes are major supportive cells in brains with important functions including providing nutrients and regulating neuronal activities. In this study, we demonstrated that astrocytes regulate amyloid precursor protein (APP) processing in neuronal cells through secretion of group IIA secretory phospholipase A2 (sPLA2-IIA). When astrocytic cells (DITNC) were mildly stimulated with the pro-inflammatory cytokines, such as TNF α and IL-1ß, sPLA2-IIA was secreted into the medium. When conditioned medium containing sPLA2-IIA was applied to human neuroblastoma (SH-SY5Y) cells, there was an increase in both cell membrane fluidity and secretion of α-secretase-cleaved soluble amyloid precursor protein (sAPPα). These changes were abrogated by KH064, a selective inhibitor of sPLA2-IIA. In addition, exposing SH-SY5Y cells to recombinant human sPLA2-IIA also increased membrane fluidity, accumulation of APP at the cell surface, and secretion of sAPPα, but without altering total expressions of APP, α-secretases and ß-site APP cleaving enzyme (BACE1). Taken together, our results provide novel information regarding a functional role of sPLA2-IIA in astrocytes for regulating APP processing in neuronal cells.


Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Astrócitos/metabolismo , Fosfolipases A2 do Grupo II/metabolismo , Neurônios/enzimologia , Neurônios/metabolismo , Peptídeos beta-Amiloides/metabolismo , Astrócitos/efeitos dos fármacos , Western Blotting , Linhagem Celular Tumoral , Membrana Celular/efeitos dos fármacos , Membrana Celular/enzimologia , Membrana Celular/metabolismo , Sobrevivência Celular , Meios de Cultivo Condicionados , Imunofluorescência , Fosfolipases A2 do Grupo II/antagonistas & inibidores , Humanos , Fluidez de Membrana/efeitos dos fármacos , Fluidez de Membrana/fisiologia , Microscopia de Fluorescência , Neurônios/efeitos dos fármacos , Fragmentos de Peptídeos/metabolismo
13.
Chem Biol ; 22(3): 369-78, 2015 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-25754474

RESUMO

Islet amyloid polypeptide (IAPP) is a hormone cosecreted with insulin. IAPP proceeds through a series of conformational changes from random coil to ß-sheet via transient α-helical intermediates. An unknown subset of these events are associated with seemingly disparate gains of function, including catalysis of self-assembly, membrane penetration, loss of membrane integrity, mitochondrial localization, and finally, cytotoxicity, a central component of diabetic pathology. A series of small molecule, α-helical mimetics, oligopyridylamides, was previously shown to target the membrane-bound α-helical oligomeric intermediates of IAPP. In this study, we develop an improved, microwave-assisted synthesis of oligopyridylamides. A series of designed tripyridylamides demonstrate that lipid-catalyzed self-assembly of IAPP can be deliberately targeted. In addition, these molecules affect IAPP-induced leakage of synthetic liposomes and cellular toxicity in insulin-secreting cells. The tripyridylamides inhibit these processes with identical rank orders of effectiveness. This indicates a common molecular basis for the disparate set of observed effects of IAPP.


Assuntos
Amidas/síntese química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Piridinas/síntese química , Amidas/química , Amidas/farmacologia , Sequência de Aminoácidos , Animais , Apoptose/fisiologia , Materiais Biomiméticos/síntese química , Materiais Biomiméticos/química , Materiais Biomiméticos/farmacologia , Linhagem Celular Tumoral , Desenho de Fármacos , Humanos , Insulinoma , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Lipossomos/química , Lipossomos/metabolismo , Fluidez de Membrana/fisiologia , Micro-Ondas , Modelos Moleculares , Dados de Sequência Molecular , Neoplasias Pancreáticas , Estrutura Secundária de Proteína , Piridinas/química , Piridinas/farmacologia , Ratos , Relação Estrutura-Atividade
14.
Gen Physiol Biophys ; 34(3): 311-21, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25730899

RESUMO

The action of a mixture of hormones (cortisol and adrenaline) on erythrocyte membrane during their binding was investigated. Changes in the membrane structure were elucidated by atomic force microscopy; microviscosity of the lipid bilayer and changes in the activity of Na(+),K(+)-ATPase at different concentrations of the hormones in erythrocyte suspension were estimated by the fluorescence method. Cortisol and adrenaline were shown to compete for the binding sites. A hormone that managed to bind nonspecifically to the membrane hindered the binding of another hormone. In a mixture of these hormones, cortisol won a competition for the binding sites; therewith, microviscosity of the membranes increased by 25%, which corresponds to a change in microviscosity produced by the action of cortisol alone. The competitive relationships affected also the Na(+),K(+)-ATPase activity, which was indicated by appearance of the second maximum of enzyme activity. It is assumed that an increase in microviscosity of erythrocyte membrane first raises the Na(+),K(+)-ATPase activity due to a growth of the maximum energy of membrane phonons, and then decreases the activity due to hindering of conformational transitions in the enzyme molecule.


Assuntos
Epinefrina/administração & dosagem , Membrana Eritrocítica/metabolismo , Membrana Eritrocítica/ultraestrutura , Hidrocortisona/administração & dosagem , Fluidez de Membrana/fisiologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Células Cultivadas , Combinação de Medicamentos , Membrana Eritrocítica/efeitos dos fármacos , Masculino , Fluidez de Membrana/efeitos dos fármacos , Ratos , Ratos Wistar , Relação Estrutura-Atividade , Viscosidade
15.
Biosystems ; 130: 1-10, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25666503

RESUMO

Living matter equals water, to a first approximation, and water transport across barriers such as membranes and epithelia is vital. Water serves two competing functions. On the one hand, it is the fundamental solvent enabling random mobility of solutes and therefore biochemical reactions and intracellular signal propagation. Homeostasis of the intracellular water volume is required such that messenger concentration encodes the stimulus and not inverse volume fluctuations. On the other hand, water flow is needed for transport of solutes to and away from cells in a directed manner, threatening volume homeostasis and signal transduction fidelity of cells. Feedback regulation of fluid transport reconciles these competing objectives. The regulatory mechanisms often span across multiple spatial scales from cellular interactions up to the architecture of organs. Open questions relate to the dependency of water fluxes and steady state volumes on control parameters and stimuli. We here review selected mathematical models of feedback regulation of fluid transport at the cell scale and identify a general "core-shell" structure of such models. We propose that fluid transport models at other spatial scales can be constructed in a generalised core-shell framework, in which the core accounts for the biophysical effects of fluid transport whilst the shell reflects the regulatory mechanisms. We demonstrate the applicability of this framework for tissue lumen growth and suggest future experiments in zebrafish to test lumen size regulation mechanisms.


Assuntos
Fluidez de Membrana/fisiologia , Modelos Teóricos , Água/fisiologia , Animais , Transporte Biológico/fisiologia , Tamanho Celular , Epitélio/fisiologia , Homeostase/fisiologia , Humanos
16.
Integr Biol (Camb) ; 7(3): 298-312, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25609037

RESUMO

During development and in adult tissues separation of phenotypically distinct cell populations is necessary to ensure proper organization and function of tissues and organs. Various phenomena, such as differential adhesion, differential mechanical tension and cell-cell repulsion, are proposed to cause boundary formation. Moreover, emerging evidence suggests that interplay between multiple such phenomena can underlie boundary formation. Boundary-forming mechanisms are commonly studied in vivo in complex embryo models or in vitro using simple model systems not reflective of in vivo boundary complexity. To better elucidate the interplay between multiple boundary formation mechanism, there is therefore a need for more relevant in vitro model systems that allow quantitative and concomitant studies of the multiple changes in cell/tissue behaviour that lead to boundary establishment. Here, we develop such a model using patterned co-cultures of two cell populations. Using a set of quantitative tools, we demonstrate that our approach allows us to study the mechanisms underlying boundary formation. We demonstrate that in our specific system differential mechanical tension and modulation of migratory behavior of cells accompany boundary formation. The design of our in vitro model system will allow researchers to obtain quantitative, integrative mechanistic data facilitating a faster and more thorough understanding of the fundamental principles underlying boundary formation.


Assuntos
Células Epiteliais/citologia , Células Epiteliais/fisiologia , Adesões Focais/fisiologia , Fluidez de Membrana/fisiologia , Morfogênese/fisiologia , Adesão Celular/fisiologia , Crescimento Celular , Linhagem Celular , Movimento Celular/fisiologia , Tamanho Celular , Técnicas de Cocultura/métodos , Humanos , Modelos Biológicos , Estresse Mecânico
17.
Am J Physiol Cell Physiol ; 308(3): C198-208, 2015 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-25428884

RESUMO

The primary cilium is an extraordinary organelle. For many years, it had the full attention of only a few dedicated scientists fascinated by its uniqueness. Unexpectedly, after decades of obscurity, it has moved very quickly into the limelight with the increasing evidence of its central role in the many genetic variations that lead to what are now known as ciliopathies. These studies implicated unique biological functions of the primary cilium, which are not completely straightforward. In parallel, and initially completely unrelated to the ciliopathies, the primary cilium was characterized functionally as an organelle that makes cells more susceptible to changes in fluid flow. Thus the primary cilium was suggested to function as a flow-sensing device. This characterization has been substantiated for many epithelial cell types over the years. Nevertheless, part of the central mechanism of signal transduction has not been explained, largely because of the substantial technical challenges of working with this delicate organelle. The current review considers the recent advances that allow us to fill some of the holes in the model of signal transduction in cilium-mediated responses to fluid flow and to pursue the physiological implications of this peculiar organelle.


Assuntos
Comunicação Celular/fisiologia , Cílios/fisiologia , Fluidez de Membrana/fisiologia , Proteínas de Membrana/metabolismo , Transdução de Sinais/fisiologia , Animais , Sinalização do Cálcio/fisiologia , Células Epiteliais/fisiologia , Humanos
18.
Biochem Biophys Res Commun ; 450(1): 366-71, 2014 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-24905496

RESUMO

It is essential to understand the role of cardiolipin (CL) in mitochondrial membrane organization given that changes in CL levels contribute to mitochondrial dysfunction in type II diabetes, ischemia-reperfusion injury, heart failure, breast cancer, and aging. Specifically, there are contradictory data on how CL influences the molecular packing of membrane phospholipids. Therefore, we determined how increasing levels of heart CL impacted molecular packing in large unilamellar vesicles, modeling heterogeneous lipid mixtures found within the mitochondrial inner membrane, using merocyanine (MC540) fluorescence. We broadly categorized lipid vesicles of equal mass as loosely packed, intermediate, and highly packed based on peak MC540 fluorescence intensity. CL had opposite effects on loosely versus highly packed vesicles. Exposure of loosely packed vesicles to increasing levels of CL dose-dependently increased membrane packing. In contrast, increasing amounts of CL in highly packed vesicles decreased the packing in a dose-dependent manner. In vesicles that were categorized as intermediate packing, CL had either no effect or decreased packing at select doses in a dose-independent manner. Altogether, the results aid in resolving some of the discrepant data by demonstrating that CL displays differential effects on membrane packing depending on the composition of the lipid environment. This has implications for mitochondrial protein activity in response to changing CL levels in microdomains of varying composition.


Assuntos
Cardiolipinas/administração & dosagem , Fluidez de Membrana/fisiologia , Lipídeos de Membrana/metabolismo , Membranas Mitocondriais/metabolismo , Fosfolipídeos/metabolismo , Lipossomas Unilamelares/metabolismo , Biomimética/métodos , Relação Dose-Resposta a Droga , Fluidez de Membrana/efeitos dos fármacos , Membranas Mitocondriais/efeitos dos fármacos
19.
J Biomech ; 47(2): 354-9, 2014 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-24326098

RESUMO

Membrane biomechanical properties are critical in modulating nutrient and metabolite exchange as well as signal transduction. Biological membranes are predominantly composed of lipids, cholesterol and proteins, and their fluidity is tightly regulated by cholesterol and lipid desaturases. To determine whether such membrane fluidity regulation occurred in mammalian cells under pressure, we investigated the effects of pressure on membrane lipid order of mouse chondrogenic ATDC5 cells and desaturase gene expression. Hydrostatic pressure linearly increased membrane lipid packing and simultaneously repressed lipid desaturase gene expression. We also showed that cholesterol mimicked and cholesterol depletion reversed those effects, suggesting that desaturase gene expression was controlled by the membrane physical state itself. This study demonstrates a new effect of hydrostatic pressure on mammalian cells and may help to identify the molecular mechanisms involved in hydrostatic pressure sensing in chondrocytes.


Assuntos
Condrócitos/enzimologia , Ácidos Graxos Dessaturases/antagonistas & inibidores , Ácidos Graxos Dessaturases/genética , Fluidez de Membrana/fisiologia , Lipídeos de Membrana/antagonistas & inibidores , Células-Tronco/enzimologia , Animais , Linhagem Celular Tumoral , Colesterol/biossíntese , Colesterol/deficiência , Colesterol/metabolismo , Condrócitos/patologia , Regulação para Baixo/genética , Ácidos Graxos Dessaturases/biossíntese , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Pressão Hidrostática , Lipídeos de Membrana/genética , Camundongos , Células-Tronco/patologia , Regulação para Cima/genética
20.
Nitric Oxide ; 35: 42-6, 2013 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-23973530

RESUMO

Smoking affects the general health of an individual, however, the red blood cells (RBCs) and their architecture are particularly vulnerable to inhaled toxins related to smoking. Smoking is one of the lifestyle diseases that are responsible for the most deaths worldwide and an individual who smokes is exposed to excessive amounts of oxidants and toxins which generate up to 10(18) free radicals in the human body. Recently, it was reported that smoking decreases RBC membrane fluidity. Here we confirm this and we show changes visible in the topography of RBC membranes, using scanning electron microscopy (SEM). RBC membranes show bubble formation of the phospholipid layer, as well as balloon-like smooth areas; while their general discoid shapes are changed to form pointed extensions. We also investigate membrane roughness using atomic force microscopy (AFM) and these results confirm SEM results. Due to the vast capability of RBCs to be adaptable, their state of well-being is a major indication for the general health status of an individual. We conclude that these changes, using an old technique in a novel application, may provide new insights and new avenues for future improvements in clinical medicine pertaining to conditions like COPD.


Assuntos
Membrana Eritrocítica/patologia , Membrana Eritrocítica/fisiologia , Fumar/sangue , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Fluidez de Membrana/fisiologia , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Fumar/epidemiologia , Superóxidos/sangue , Adulto Jovem
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