Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 46
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Molecules ; 28(18)2023 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-37764460

RESUMO

The widespread consumption of plant-based drinks, driven by health and dietary reasons (including cow's milk allergy, lactose intolerance, milk protein intolerance, following a vegetarian or vegan diet) necessitates automated and accurate test methods. Our study demonstrates the simultaneous determination of protein components and total protein concentrations in plant-based milk alternatives using a rapid and reproducible microchip gel electrophoretic method. As expected, the electrophoretic profiles of each plant-based drink differed. Based on our analyses and statistical evaluation, it can be determined that the protein profiles of different plant-based beverages do not differ significantly between different manufacturers or different expiry dates. The measured total protein content was compared with the nominal values, i.e., the values stated on the beverage labels. As the number of consumers of functional and specialized plant-based milk alternatives continues to rise, it is important to prioritize methods that provide qualitative and quantitative information on protein composition and other nutrients.


Assuntos
Intolerância à Lactose , Técnicas Analíticas Microfluídicas , Animais , Bovinos , Feminino , Proteínas do Leite , Nutrientes , Bebidas , Dieta Vegana , Intolerância Alimentar
2.
Biomolecules ; 13(7)2023 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-37509087

RESUMO

Functional changes in chaperone systems play a major role in the decline of cognition and contribute to neurological pathologies, such as Alzheimer's disease (AD). While such a decline may occur naturally with age or with stress or trauma, the mechanisms involved have remained elusive. The current models suggest that amyloid-ß (Aß) plaque formation leads to the hyperphosphorylation of tau by a Hsp90-dependent process that triggers tau neurofibrillary tangle formation and neurotoxicity. Several co-chaperones of Hsp90 can influence the phosphorylation of tau, including FKBP51, FKBP52 and PP5. In particular, elevated levels of FKBP51 occur with age and stress and are further elevated in AD. Recently, the dihydropyridine LA1011 was shown to reduce tau pathology and amyloid plaque formation in transgenic AD mice, probably through its interaction with Hsp90, although the precise mode of action is currently unknown. Here, we present a co-crystal structure of LA1011 in complex with a fragment of Hsp90. We show that LA1011 can disrupt the binding of FKBP51, which might help to rebalance the Hsp90-FKBP51 chaperone machinery and provide a favourable prognosis towards AD. However, without direct evidence, we cannot completely rule out effects on other Hsp90-co-chaprone complexes and the mechanisms they are involved in, including effects on Hsp90 client proteins. Nonetheless, it is highly significant that LA1011 showed promise in our previous AD mouse models, as AD is generally a disease affecting older patients, where slowing of disease progression could result in AD no longer being life limiting. The clinical value of LA1011 and its possible derivatives thereof remains to be seen.


Assuntos
Doença de Alzheimer , Di-Hidropiridinas , Proteínas de Choque Térmico HSP90 , Animais , Camundongos , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides , Proteínas de Choque Térmico HSP90/metabolismo , Camundongos Transgênicos , Chaperonas Moleculares/metabolismo , Proteínas tau/metabolismo , Di-Hidropiridinas/química , Di-Hidropiridinas/metabolismo
3.
Molecules ; 27(20)2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-36296523

RESUMO

The profiling of bacterial fatty acids is a well-established technique in identifying and classifying bacteria. Cultivation conditions may affect the biosynthesis, thereby, changing the fatty acid profile in bacteria. The effect of the culture conditions on the fatty acid components of Pseudomonas aeruginosa PAO1, Pseudomonas aeruginosa ATCC 27853, Pseudomonas aeruginosa polyresistant and Pseudomonas putida all are aligned to the genus Pseudomonas. The fatty acids in the lipopolysaccharides of Pseudomonas aeruginosa PAO1 were also examined. The effects of the cultivation conditions were followed by using agar and blood agar media at the characteristic temperatures, 25 °C, 37 °C and 42 °C, respectively, and an analysis was made during the 1st, 3rd and 5th day following inoculation. In addition to quantitative differences, we also experienced qualitative differences in the fatty acid profiles which detect newly appearing fatty acids, due to changes in environmental factors. The application of ionic liquid-based column unveils new possibilities for the analyses of fatty acids in GC-MS experiments for bacterial fatty acid profiling. The validation results (response linearity, limit of detection, limit of quantification, system suitability, intraday and interday repeatability and accuracy) show the high separation efficiency of the ionic liquid-based column in the analyses.


Assuntos
Líquidos Iônicos , Pseudomonas putida , Cromatografia Gasosa-Espectrometria de Massas/métodos , Ácidos Graxos/análise , Lipopolissacarídeos , Ágar , Pseudomonas aeruginosa
4.
Biomedicines ; 10(5)2022 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-35625909

RESUMO

Mild stress could help cells to survive more severe environmental or pathophysiological conditions. In the current study, we investigated the cellular mechanisms which contribute to the development of stress tolerance upon a prolonged (0-12 h) fever-like (40 °C) or a moderate (42.5 °C) hyperthermia in mammalian Chinese Hamster Ovary (CHO) cells. Our results indicate that mild heat triggers a distinct, dose-dependent remodeling of the cellular lipidome followed by the expression of heat shock proteins only at higher heat dosages. A significant elevation in the relative concentration of saturated membrane lipid species and specific lysophosphatidylinositol and sphingolipid species suggests prompt membrane microdomain reorganization and an overall membrane rigidification in response to the fluidizing heat in a time-dependent manner. RNAseq experiments reveal that mild heat initiates endoplasmic reticulum stress-related signaling cascades resulting in lipid rearrangement and ultimately in an elevated resistance against membrane fluidization by benzyl alcohol. To protect cells against lethal, protein-denaturing high temperatures, the classical heat shock protein response was required. The different layers of stress response elicited by different heat dosages highlight the capability of cells to utilize multiple tools to gain resistance against or to survive lethal stress conditions.

5.
Cells ; 10(6)2021 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-34199944

RESUMO

PARP2 is a DNA repair protein. The deletion of PARP2 induces mitochondrial biogenesis and mitochondrial activity by increasing NAD+ levels and inducing SIRT1 activity. We show that the silencing of PARP2 causes mitochondrial fragmentation in myoblasts. We assessed multiple pathways that can lead to mitochondrial fragmentation and ruled out the involvement of mitophagy, the fusion-fission machinery, SIRT1, and mitochondrial unfolded protein response. Nevertheless, mitochondrial fragmentation was reversed by treatment with strong reductants, such as reduced glutathione (GSH), N-acetyl-cysteine (NAC), and a mitochondria-specific antioxidant MitoTEMPO. The effect of MitoTEMPO on mitochondrial morphology indicates the production of reactive oxygen species of mitochondrial origin. Elimination of reactive oxygen species reversed mitochondrial fragmentation in PARP2-silenced cells.


Assuntos
Inativação Gênica , Mitocôndrias , Dinâmica Mitocondrial/genética , Poli(ADP-Ribose) Polimerases , Espécies Reativas de Oxigênio/metabolismo , Células Hep G2 , Humanos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Poli(ADP-Ribose) Polimerases/genética , Poli(ADP-Ribose) Polimerases/metabolismo , Sirtuína 1/genética , Sirtuína 1/metabolismo
6.
Br J Pharmacol ; 176(9): 1222-1234, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30737967

RESUMO

BACKGROUND AND PURPOSE: A new class of dihydropyridine derivatives, which act as co-inducers of heat shock protein but are devoid of calcium channel antagonist and vasodilator effects, has recently been developed with the purpose of selectively targeting neurodegeneration. Here, we evaluated the action of one of these novel compounds LA1011 on neurovascular coupling in the ischaemic rat cerebral cortex. As a reference, we applied nimodipine, a vasodilator dihydropyridine and well-known calcium channel antagonist. EXPERIMENTAL APPROACH: Rats were treated with LA1011 or nimodipine, either by chronic, systemic (LA1011), or acute, local administration (LA1011 and nimodipine). In the latter treatment group, global forebrain ischaemia was induced in half of the animals by bilateral common carotid artery occlusion under isoflurane anaesthesia. Functional hyperaemia in the somatosensory cortex was created by mechanical stimulation of the contralateral whisker pad under α-chloralose anaesthesia. Spreading depolarization (SD) events were elicited subsequently by 1 M KCl. Local field potential and cerebral blood flow (CBF) in the parietal somatosensory cortex were monitored by electrophysiology and laser Doppler flowmetry. KEY RESULTS: LA1011 did not alter CBF, but intensified SD, presumably indicating the co-induction of heat shock proteins, and, perhaps an anti-inflammatory effect. Nimodipine attenuated evoked potentials and SD. In addition to the elevation of baseline CBF, nimodipine augmented hyperaemia in response to both somatosensory stimulation and SD, particularly under ischaemia. CONCLUSIONS AND IMPLICATIONS: In contrast to the CBF improvement achieved with nimodipine, LA1011 seems not to have discernible cerebrovascular effects but may up-regulate the stress response.


Assuntos
Bloqueadores dos Canais de Cálcio/farmacologia , Circulação Cerebrovascular/efeitos dos fármacos , Di-Hidropiridinas/farmacologia , Córtex Somatossensorial/efeitos dos fármacos , Animais , Masculino , Ratos , Ratos Sprague-Dawley
7.
Biochim Biophys Acta Mol Cell Biol Lipids ; 1863(11): 1399-1412, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30077797

RESUMO

There is a growing body of evidence that poly(ADP-ribose) polymerase-2 (PARP2), although originally described as a DNA repair protein, has a widespread role as a metabolic regulator. We show that the ablation of PARP2 induced characteristic changes in the lipidome. The silencing of PARP2 induced the expression of sterol regulatory element-binding protein-1 and -2 and initiated de novo cholesterol biosynthesis in skeletal muscle. Increased muscular cholesterol was shunted to muscular biosynthesis of dihydrotestosterone, an anabolic steroid. Thus, skeletal muscle fibers in PARP2-/- mice were stronger compared to those of their wild-type littermates. In addition, we detected changes in the dynamics of the cell membrane, suggesting that lipidome changes also affect the biophysical characteristics of the cell membrane. In in silico and wet chemistry studies, we identified lipid species that can decrease the expression of PARP2 and potentially phenocopy the genetic abruption of PARP2, including artificial steroids. In view of these observations, we propose a new role for PARP2 as a lipid-modulated regulator of lipid metabolism.


Assuntos
Colesterol/metabolismo , Técnicas de Inativação de Genes , Músculo Esquelético/metabolismo , Poli(ADP-Ribose) Polimerases/genética , Animais , Linhagem Celular , Membrana Celular/metabolismo , Di-Hidrotestosterona/metabolismo , Homeostase , Metabolismo dos Lipídeos , Masculino , Camundongos , Poli(ADP-Ribose) Polimerases/metabolismo , Ratos , Proteína de Ligação a Elemento Regulador de Esterol 1/genética
8.
Cell Commun Signal ; 16(1): 51, 2018 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-30157875

RESUMO

BACKGROUND: The outcome of cancer therapy is greatly defined by the ability of a tumor cell to evade treatment and re-establish its bulk mass after medical interventions. Consequently, there is an urgent need for the characterization of molecules affecting tumor reoccurrence. The phosphatase of regenerating liver 3 (PRL3) protein was recently emerged among the targets that could affect such a phenomenon. METHODS: The expression induction of PRL3 in melanoma cells treated with chemotherapeutic agents was assessed by western blotting. The effect of PRL3 expression on cancer growth was investigated both in vitro and in vivo. The association of PRL3 with the caveolae structures of the plasma membrane was analyzed by detergent free raft purification. The effect of PRL3 expression on the membrane organization was assayed by electron microscopy and by membrane biophysical measurements. Purification of the plasma membrane fraction and co-immunoprecipitation were used to evaluate the altered protein composition of the plasma membrane upon PRL3 expression. RESULTS: Here, we identified PRL3 as a genotoxic stress-induced oncogene whose expression is significantly increased by the presence of classical antitumor therapeutics. Furthermore, we successfully connected the presence of this oncogene with increased tumor growth, which implies that tumor cells can utilize PRL3 effects as a survival strategy. We further demonstrated the molecular mechanism that is connected with the pro-growth action of PRL3, which is closely associated with its localization to the caveolae-type lipid raft compartment of the plasma membrane. In our study, PRL3 was associated with distinct changes in the plasma membrane structure and in the caveolar proteome, such as the dephosphorylation of integrin ß1 at Thr788/Thr789 and the increased partitioning of Rac1 to the plasma membrane. These alterations at the plasma membrane were further associated with the elevation of cyclin D1 in the nucleus. CONCLUSIONS: This study identifies PRL3 as an oncogene upregulated in cancer cells upon exposure to anticancer therapeutics. Furthermore, this work contributes to the existing knowledge on PRL3 function by characterizing its association with the caveolae-like domains of the plasma membrane and their resident proteins.


Assuntos
Cavéolas/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Melanoma/patologia , Proteínas de Neoplasias/genética , Proteínas Tirosina Fosfatases/genética , Transdução de Sinais/efeitos dos fármacos , Animais , Carcinogênese/efeitos dos fármacos , Cavéolas/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Melanoma/tratamento farmacológico , Melanoma/metabolismo , Camundongos , Camundongos Endogâmicos C57BL
9.
Front Mol Biosci ; 5: 51, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29930942

RESUMO

Chaperones play a pivotal role in protein homeostasis, but with age their ability to clear aggregated and damaged protein from cells declines. Tau pathology is a driver of a variety of neurodegenerative disease and in Alzheimer's disease (AD) it appears to be precipitated by the formation of amyloid-ß (Aß) aggregates. Aß-peptide appears to trigger Tau hyperphosphorylation, formation of neurofibrillary tangles and neurotoxicity. Recently, dihydropyridine derivatives were shown to upregulate the heat shock response (HSR) and provide a neuroprotective effect in an APPxPS1 AD mouse model. The HSR response was only seen in diseased cells and consequently these compounds were defined as co-inducers since they upregulate chaperones and co-chaperones only when a pathological state is present. We show for compounds tested herein, that they target predominantly the C-terminal domain of Hsp90, but show some requirement for its middle-domain, and that binding stimulates the chaperones ATPase activity. We identify the site for LA1011 binding and confirm its identification by mutagenesis. We conclude, that binding compromises Hsp90's ability to chaperone, by modulating its ATPase activity, which consequently induces the HSR in diseased cells. Collectively, this represents the mechanism by which the normalization of neurofibrillary tangles, preservation of neurons, reduced tau pathology, reduced amyloid plaque, and increased dendritic spine density in the APPxPS1 Alzheimer's mouse model is initiated. Such dihydropyridine derivatives therefore represent potential pharmaceutical candidates for the therapy of neurodegenerative disease, such as AD.

10.
Sci Rep ; 7(1): 15643, 2017 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-29142280

RESUMO

The current research on cellular heat stress management focuses on the roles of heat shock proteins (HSPs) and the proteostasis network under severe stress conditions. The mild, fever-type stress and the maintenance of membrane homeostasis are less well understood. Herein, we characterized the acute effect of mild, fever-range heat shock on membrane organization, and HSP synthesis and localization in two mammalian cell lines, to delineate the role of membranes in the sensing and adaptation to heat. A multidisciplinary approach combining ultrasensitive fluorescence microscopy and lipidomics revealed the molecular details of novel cellular "eustress", when cells adapt to mild heat by maintaining membrane homeostasis, activating lipid remodeling, and redistributing chaperone proteins. Notably, this leads to acquired thermotolerance in the complete absence of the induction of HSPs. At higher temperatures, additional defense mechanisms are activated, including elevated expression of molecular chaperones, contributing to an extended stress memory and acquired thermotolerance.


Assuntos
Adaptação Fisiológica/genética , Febre/genética , Proteínas de Choque Térmico/genética , Resposta ao Choque Térmico/genética , Animais , Células CHO , Sobrevivência Celular/genética , Cricetinae , Cricetulus , Febre/patologia , Temperatura Alta/efeitos adversos
11.
PLoS One ; 12(3): e0173739, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28282432

RESUMO

Cell membranes actively participate in stress sensing and signalling. Here we present the first in-depth lipidomic analysis to characterize alterations in the fission yeast Schizosaccharomyces pombe in response to mild heat stress (HS). The lipidome was assessed by a simple one-step methanolic extraction. Genetic manipulations that altered triglyceride (TG) content in the absence or presence of HS gave rise to distinct lipidomic fingerprints for S. pombe. Cells unable to produce TG demonstrated long-lasting growth arrest and enhanced signalling lipid generation. Our results reveal that metabolic crosstalk between membrane and storage lipids facilitates homeostatic maintenance of the membrane physical/chemical state that resists negative effects on cell growth and viability in response to HS. We propose a novel stress adaptation mechanism in which heat-induced TG synthesis contributes to membrane rigidization by accommodating unsaturated fatty acids of structural lipids, enabling their replacement by newly synthesized saturated fatty acids.


Assuntos
Membrana Celular/metabolismo , Resposta ao Choque Térmico/fisiologia , Schizosaccharomyces/fisiologia , Triglicerídeos/metabolismo , Metabolismo dos Lipídeos , Lipídeos/análise , Espectrometria de Massas/métodos , Lipídeos de Membrana/metabolismo , Schizosaccharomyces/crescimento & desenvolvimento , Proteínas de Schizosaccharomyces pombe/metabolismo , Transdução de Sinais , Triglicerídeos/biossíntese
12.
J Alzheimers Dis ; 53(2): 557-71, 2016 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-27163800

RESUMO

Heat shock proteins (Hsps) have chaperone activity and play a pivotal role in the homeostasis of proteins by preventing misfolding, by clearing aggregated and damaged proteins from cells, and by maintaining proteins in an active state. Alzheimer's disease (AD) is thought to be caused by amyloid-ß peptide that triggers tau hyperphosphorylation, which is neurotoxic. Although proteostasis capacity declines with age and facilitates the manifestation of neurodegenerative diseases such as AD, the upregulation of chaperones improves prognosis. Our research goal is to identify potent Hsp co-inducers that enhance protein homeostasis for the treatment of AD, especially 1,4-dihydropyridine derivatives optimized for their ability to modulate cellular stress responses. Based on favorable toxicological data and Hsp co-inducing activity, LA1011 was selected for the in vivo analysis of its neuroprotective effect in the APPxPS1 mouse model of AD. Here, we report that 6 months of LA1011 administration effectively improved the spatial learning and memory functions in wild type mice and eliminated neurodegeneration in double mutant mice. Furthermore, Hsp co-inducer therapy preserves the number of neurons, increases dendritic spine density, and reduces tau pathology and amyloid plaque formation in transgenic AD mice. In conclusion, the Hsp co-inducer LA1011 is neuroprotective and therefore is a potential pharmaceutical candidate for the therapy of neurodegenerative diseases, particularly AD.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Di-Hidropiridinas/uso terapêutico , Proteínas de Choque Térmico/metabolismo , Fármacos Neuroprotetores/uso terapêutico , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Precursor de Proteína beta-Amiloide/genética , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/ultraestrutura , Linhagem Celular Tumoral , Espinhas Dendríticas/patologia , Espinhas Dendríticas/ultraestrutura , Di-Hidropiridinas/química , Di-Hidropiridinas/farmacologia , Modelos Animais de Doenças , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Humanos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação/genética , Neuroblastoma/patologia , Fármacos Neuroprotetores/farmacologia , Presenilina-1/genética , Presenilina-1/metabolismo , Proteínas tau/metabolismo
13.
Cell Stress Chaperones ; 21(2): 327-38, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26631139

RESUMO

Changes in the levels of three structurally and functionally different important thermoprotectant molecules, namely small heat shock proteins (sHsps), trehalose, and lipids, have been investigated upon heat shock in Schizosaccharomyces pombe. Both α-crystallin-type sHsps (Hsp15.8 and Hsp16) were induced after prolonged high-temperature treatment but with different kinetic profiles. The shsp null mutants display a weak, but significant, heat sensitivity indicating their importance in the thermal stress management. The heat induction of sHsps is different in wild type and in highly heat-sensitive trehalose-deficient (tps1Δ) cells; however, trehalose level did not show significant alteration in shsp mutants. The altered timing of trehalose accumulation and induction of sHsps suggest that the disaccharide might provide protection at the early stage of the heat stress while elevated amount of sHsps are required at the later phase. The cellular lipid compositions of two different temperature-adapted wild-type S. pombe cells are also altered according to the rule of homeoviscous adaptation, indicating their crucial role in adapting to the environmental temperature changes. Both Hsp15.8 and Hsp16 are able to bind to different lipids isolated from S. pombe, whose interaction might provide a powerful protection against heat-induced damages of the membranes. Our data suggest that all the three investigated thermoprotectant macromolecules play a pivotal role during the thermal stress management in the fission yeast.


Assuntos
Proteínas de Choque Térmico Pequenas/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Schizosaccharomyces/metabolismo , Trealose/metabolismo , Regulação Fúngica da Expressão Gênica , Proteínas de Choque Térmico Pequenas/genética , Temperatura Alta , Bicamadas Lipídicas/metabolismo , Metabolismo dos Lipídeos , Mutação , Schizosaccharomyces/citologia , Schizosaccharomyces/genética , Proteínas de Schizosaccharomyces pombe/genética , Estresse Fisiológico , Trealose/genética
14.
Prog Lipid Res ; 59: 38-53, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25969421

RESUMO

Nowadays we understand cell membranes not as a simple double lipid layer but as a collection of complex and dynamic protein-lipid structures and microdomains that serve as functional platforms for interacting signaling lipids and proteins. Membrane lipids and lipid structures participate directly as messengers or regulators of signal transduction. In addition, protein-lipid interactions participate in the localization of signaling protein partners to specific membrane microdomains. Thus, lipid alterations change cell signaling that are associated with a variety of diseases including cancer, obesity, neurodegenerative disorders, cardiovascular pathologies, etc. This article reviews the newly emerging field of membrane lipid therapy which involves the pharmacological regulation of membrane lipid composition and structure for the treatment of diseases. Membrane lipid therapy proposes the use of new molecules specifically designed to modify membrane lipid structures and microdomains as pharmaceutical disease-modifying agents by reversing the malfunction or altering the expression of disease-specific protein or lipid signal cascades. Here, we provide an in-depth analysis of this emerging field, especially its molecular bases and its relevance to the development of innovative therapeutic approaches.


Assuntos
Membrana Celular/metabolismo , Lipídeos de Membrana/fisiologia , Doenças Metabólicas/tratamento farmacológico , Animais , Membrana Celular/efeitos dos fármacos , Descoberta de Drogas , Humanos , Lipídeos de Membrana/uso terapêutico , Terapia de Alvo Molecular , Proteína Quinase C/metabolismo , Transdução de Sinais
15.
PLoS One ; 9(2): e89136, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24586549

RESUMO

Eukaryotic cells exhibit a characteristic response to hyperthermic treatment, involving morphological and cytoskeletal alterations and the induction of heat shock protein synthesis. Small GTPases of the Ras superfamily are known to serve as molecular switches which mediate responses to extracellular stimuli. We addressed here how small GTPase Rac1 integrates signals from heat stress and simultaneously induces various cellular changes in mammalian cells. As evidence that Rac1 is implicated in the heat shock response, we first demonstrated that both mild (41.5°C) and severe (43°C) heat shock induced membrane translocation of Rac1. Following inhibition of the activation or palmitoylation of Rac1, the size of its plasma membrane-bound pool was significantly decreased while the heat shock-induced alterations in the cytoskeleton and cell morphology were prevented. We earlier documented that the size distribution pattern of cholesterol-rich rafts is temperature dependent and hypothesized that this is coupled to the triggering mechanism of stress sensing and signaling. Interestingly, when plasma membrane localization of Rac1 was inhibited, a different and temperature independent average domain size was detected. In addition, inhibition of the activation or palmitoylation of Rac1 resulted in a strongly decreased expression of the genes of major heat shock proteins hsp25 and hsp70 under both mild and severe heat stress conditions.


Assuntos
Citoesqueleto/metabolismo , Proteínas de Choque Térmico HSP70/genética , Proteínas de Choque Térmico/genética , Resposta ao Choque Térmico , Melanoma Experimental/patologia , Microdomínios da Membrana/metabolismo , Proteínas de Neoplasias/genética , Proteínas rac1 de Ligação ao GTP/metabolismo , Citoesqueleto de Actina/metabolismo , Animais , Colesterol/metabolismo , Regulação Neoplásica da Expressão Gênica , Lipoilação , Fluidez de Membrana , Camundongos , Chaperonas Moleculares , Transporte Proteico
16.
Biochim Biophys Acta ; 1838(6): 1594-618, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24374314

RESUMO

The classic heat shock (stress) response (HSR) was originally attributed to protein denaturation. However, heat shock protein (Hsp) induction occurs in many circumstances where no protein denaturation is observed. Recently considerable evidence has been accumulated to the favor of the "Membrane Sensor Hypothesis" which predicts that the level of Hsps can be changed as a result of alterations to the plasma membrane. This is especially pertinent to mild heat shock, such as occurs in fever. In this condition the sensitivity of many transient receptor potential (TRP) channels is particularly notable. Small temperature stresses can modulate TRP gating significantly and this is influenced by lipids. In addition, stress hormones often modify plasma membrane structure and function and thus initiate a cascade of events, which may affect HSR. The major transactivator heat shock factor-1 integrates the signals originating from the plasma membrane and orchestrates the expression of individual heat shock genes. We describe how these observations can be tested at the molecular level, for example, with the use of membrane perturbers and through computational calculations. An important fact which now starts to be addressed is that membranes are not homogeneous nor do all cells react identically. Lipidomics and cell profiling are beginning to address the above two points. Finally, we observe that a deregulated HSR is found in a large number of important diseases where more detailed knowledge of the molecular mechanisms involved may offer timely opportunities for clinical interventions and new, innovative drug treatments. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.


Assuntos
Membrana Celular/metabolismo , Proteínas de Choque Térmico/metabolismo , Lipídeos de Membrana/metabolismo , Doenças Neurodegenerativas/terapia , Animais , Resposta ao Choque Térmico/fisiologia , Humanos , Doenças Neurodegenerativas/metabolismo
17.
Int J Hyperthermia ; 29(5): 491-9, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23841917

RESUMO

Hyperthermia is a promising treatment modality for cancer in combination both with radio- and chemotherapy. In spite of its great therapeutic potential, the underlying molecular mechanisms still remain to be clarified. Due to lipid imbalances and 'membrane defects' most of the tumour cells possess elevated membrane fluidity. However, further increasing membrane fluidity to sensitise to chemo- or radiotherapy could have some other effects. In fact, hyperfluidisation of cell membrane induced by membrane fluidiser initiates a stress response as the heat shock protein response, which may modulate positively or negatively apoptotic cell death. Overviewing some recent findings based on a technology allowing direct imaging of lipid rafts in live cells and lipidomics, novel aspects of the intimate relationship between the 'membrane stress' of tumour cells and the cellular heat shock response will be highlighted. Our findings lend support to both the importance of membrane remodelling and the release of lipid signals initiating stress protein response, which can operate in tandem to control the extent of the ultimate cellular thermosensitivity. Overall, we suggest that the fluidity variable of membranes should be used as an independent factor for predicting the efficacy of combinational cancer therapies.


Assuntos
Hipertermia Induzida , Fluidez de Membrana , Neoplasias/terapia , Animais , Membrana Celular/metabolismo , Proteínas de Choque Térmico/metabolismo , Humanos , Metabolismo dos Lipídeos , Neoplasias/metabolismo
18.
FEBS Lett ; 587(13): 1970-80, 2013 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-23684645

RESUMO

Heat stress is a common and, therefore, an important environmental impact on cells and organisms. While much attention has been paid to severe heat stress, moderate temperature elevations are also important. Here we discuss temperature sensing and how responses to heat stress are not necessarily dependent on denatured proteins. Indeed, it is clear that membrane lipids have a pivotal function. Details of membrane lipid changes and the associated production of signalling metabolites are described and suggestions made as to how the interconnected signalling network could be modified for helpful intervention in disease.


Assuntos
Resposta ao Choque Térmico , Lipídeos/fisiologia , Animais , Membrana Celular/fisiologia , Humanos , Metabolismo dos Lipídeos , Proteínas de Membrana/fisiologia , Transdução de Sinais
19.
Curr Pharm Des ; 19(3): 430-40, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-22920897

RESUMO

Tumor specific cell surface localization and release of the stress inducible heat shock protein 70 (Hsp70) stimulate the immune system against cancer cells. A key immune stimulatory function of tumor-derived Hsp70 has been exemplified with the murine melanoma cell model, B16 overexpressing exogenous Hsp70. Despite the therapeutic potential mechanism of Hsp70 transport to the surface and release remained poorly understood. We investigated principles of Hsp70 trafficking in B16 melanoma cells with low and high level of Hsp70. In cells with low level of Hsp70 apparent trafficking of Hsp70 was mediated by endosomes. Excess Hsp70 triggered a series of changes such as a switch of Hsp70 trafficking from endosomes to lysosomes and a concomitant accumulation of Hsp70 in lysosomes. Moreover, lysosomal rerouting resulted in an elevated concentration of surface Hsp70 and enabled active release of Hsp70. In fact, hyperthermia, a clinically applicable approach triggered immediate active lysosomal release of soluble Hsp70 from cells with excess Hsp70. Furthermore, excess Hsp70 enabled targeting of internalized surface Hsp70 to lysosomes, allowing in turn heat-induced secretion of surface Hsp70. Altogether, we show that excess Hsp70 expressed in B16 melanoma cells diverts Hsp70 trafficking from endosomes to lysosomes, thereby supporting its surface localization and lysosomal release. Controlled excess-induced lysosomal rerouting and secretion of Hsp70 is proposed as a promising tool to stimulate anti-tumor immunity targeting melanoma.


Assuntos
Adjuvantes Imunológicos/administração & dosagem , Antineoplásicos/administração & dosagem , Sistemas de Liberação de Medicamentos/tendências , Proteínas de Choque Térmico HSP70/imunologia , Lisossomos/imunologia , Melanoma/imunologia , Animais , Sistemas de Liberação de Medicamentos/métodos , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Melanoma/tratamento farmacológico , Melanoma/metabolismo , Melanoma Experimental , Camundongos , Transporte Proteico/efeitos dos fármacos , Transporte Proteico/fisiologia
20.
Curr Pharm Des ; 19(3): 309-46, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-22920902

RESUMO

According to the "membrane sensor" hypothesis, the membrane's physical properties and microdomain organization play an initiating role in the heat shock response. Clinical conditions such as cancer, diabetes and neurodegenerative diseases are all coupled with specific changes in the physical state and lipid composition of cellular membranes and characterized by altered heat shock protein levels in cells suggesting that these "membrane defects" can cause suboptimal hsp-gene expression. Such observations provide a new rationale for the introduction of novel, heat shock protein modulating drug candidates. Intercalating compounds can be used to alter membrane properties and by doing so normalize dysregulated expression of heat shock proteins, resulting in a beneficial therapeutic effect for reversing the pathological impact of disease. The membrane (and lipid) interacting hydroximic acid (HA) derivatives discussed in this review physiologically restore the heat shock protein stress response, creating a new class of "membrane-lipid therapy" pharmaceuticals. The diseases that HA derivatives potentially target are diverse and include, among others, insulin resistance and diabetes, neuropathy, atrial fibrillation, and amyotrophic lateral sclerosis. At a molecular level HA derivatives are broad spectrum, multi-target compounds as they fluidize yet stabilize membranes and remodel their lipid rafts while otherwise acting as PARP inhibitors. The HA derivatives have the potential to ameliorate disparate conditions, whether of acute or chronic nature. Many of these diseases presently are either untreatable or inadequately treated with currently available pharmaceuticals. Ultimately, the HA derivatives promise to play a major role in future pharmacotherapy.


Assuntos
Pleiotropia Genética/fisiologia , Proteínas de Choque Térmico/biossíntese , Resposta ao Choque Térmico/fisiologia , Homeostase/fisiologia , Oximas/metabolismo , Animais , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/genética , Humanos , Lipídeos de Membrana/química , Lipídeos de Membrana/genética , Lipídeos de Membrana/metabolismo , Oximas/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...