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1.
Calcif Tissue Int ; 2024 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-39276238

RESUMO

We and others have shown that application of high-level mechanical loading promotes the formation of transient plasma membrane disruptions (PMD) which initiate mechanotransduction. We hypothesized that increasing osteocyte cell membrane fragility, by disrupting the cytoskeleton-associated protein ß2-spectrin (Sptbn1), could alter osteocytic responses and bone adaptation to loading in a PMD-related fashion. In MLO-Y4 cells, treatment with the spectrin-disrupting agent diamide or knockdown of Sptbn1 via siRNA increased the number of PMD formed by fluid shear stress. Primary osteocytes from an osteocyte-targeted DMP1-Cre Sptbn1 conditional knockout (CKO) model mimicked trends seen with diamide and siRNA treatment and suggested the creation of larger PMD, which repaired more slowly, for a given level of stimulus. Post-wounding cell survival was impaired in all three models, and calcium signaling responses from the wounded osteocyte were mildly altered in Sptbn1 CKO cultures. Although Sptbn1 CKO mice did not demonstrate an altered skeletal phenotype as compared to WT littermates under baseline conditions, they showed a blunted increase in cortical thickness when subjected to an osteogenic tibial loading protocol as well as evidence of increased osteocyte death (increased lacunar vacancy) in the loaded limb after 2 weeks of loading. The impaired post-wounding cell viability and impaired bone adaptation seen with Sptbn1 disruption support the existence of an important role for Sptbn1, and PMD formation, in osteocyte mechanotransduction and bone adaptation to mechanical loading.

2.
Physiol Rev ; 95(4): 1205-40, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26336031

RESUMO

Eukaryotic cells have been confronted throughout their evolution with potentially lethal plasma membrane injuries, including those caused by osmotic stress, by infection from bacterial toxins and parasites, and by mechanical and ischemic stress. The wounded cell can survive if a rapid repair response is mounted that restores boundary integrity. Calcium has been identified as the key trigger to activate an effective membrane repair response that utilizes exocytosis and endocytosis to repair a membrane tear, or remove a membrane pore. We here review what is known about the cellular and molecular mechanisms of membrane repair, with particular emphasis on the relevance of repair as it relates to disease pathologies. Collective evidence reveals membrane repair employs primitive yet robust molecular machinery, such as vesicle fusion and contractile rings, processes evolutionarily honed for simplicity and success. Yet to be fully understood is whether core membrane repair machinery exists in all cells, or whether evolutionary adaptation has resulted in multiple compensatory repair pathways that specialize in different tissues and cells within our body.


Assuntos
Membrana Celular/fisiologia , Cicatrização/fisiologia , Animais , Cálcio/metabolismo , Membrana Celular/metabolismo , Endocitose/fisiologia , Exocitose/fisiologia , Humanos
3.
Calcif Tissue Int ; 104(2): 224-234, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30357446

RESUMO

Osteocytes experience plasma membrane disruptions (PMD) that initiate mechanotransduction both in vitro and in vivo in response to mechanical loading, suggesting that osteocytes use PMD to sense and adapt to mechanical stimuli. PMD repair is crucial for cell survival; antioxidants (e.g., alpha-tocopherol, also known as Vitamin E) promote repair while reactive oxygen species (ROS), which can accumulate during exercise, inhibit repair. The goal of this study was to determine whether depleting Vitamin E in the diet would impact osteocyte survival and bone adaptation with loading. Male CD-1 mice (3 weeks old) were fed either a regular diet (RD) or Vitamin E-deficient diet (VEDD) for up to 11 weeks. Mice from each dietary group either served as sedentary controls with normal cage activity, or were subjected to treadmill exercise (one bout of exercise or daily exercise for 5 weeks). VEDD-fed mice showed more PMD-affected osteocytes (+ 50%) after a single exercise bout suggesting impaired PMD repair following Vitamin E deprivation. After 5 weeks of daily exercise, VEDD mice failed to show an exercise-induced increase in osteocyte PMD formation, and showed signs of increased osteocytic oxidative stress and impaired osteocyte survival. Surprisingly, exercise-induced increases in cortical bone formation rate were only significant for VEDD-fed mice. This result may be consistent with previous studies in skeletal muscle, where myocyte PMD repair failure (e.g., with muscular dystrophy) initially triggers hypertrophy but later leads to widespread degeneration. In vitro, mechanically wounded MLO-Y4 cells displayed increased post-wounding necrosis (+ 40-fold) in the presence of H2O2, which could be prevented by Vitamin E pre-treatment. Taken together, our data support the idea that antioxidant-influenced osteocyte membrane repair is a vital aspect of bone mechanosensation in the osteocytic control of PMD-driven bone adaptation.


Assuntos
Membrana Celular/fisiologia , Osteócitos/fisiologia , Regeneração/fisiologia , Deficiência de Vitamina E/fisiopatologia , Vitamina E/metabolismo , Animais , Reabsorção Óssea/metabolismo , Membrana Celular/metabolismo , Membrana Celular/patologia , Permeabilidade da Membrana Celular/fisiologia , Sobrevivência Celular/efeitos dos fármacos , Masculino , Mecanotransdução Celular/efeitos dos fármacos , Mecanotransdução Celular/fisiologia , Camundongos , Osteócitos/metabolismo , Condicionamento Físico Animal/fisiologia , Vitamina E/farmacologia , Deficiência de Vitamina E/metabolismo , Suporte de Carga/fisiologia
4.
J Membr Biol ; 249(4): 569-76, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27312328

RESUMO

Electroporation-based treatments and other therapies that permeabilize the plasma membrane have been shown to be more devastating to malignant cells than to normal cells. In this study, we asked if a difference in repair capacity could explain this observed difference in sensitivity. Membrane repair was investigated by disrupting the plasma membrane using laser followed by monitoring fluorescent dye entry over time in seven cancer cell lines, an immortalized cell line, and a normal primary cell line. The kinetics of repair in living cells can be directly recorded using this technique, providing a sensitive index of repair capacity. The normal primary cell line of all tested cell lines exhibited the slowest rate of dye entry after laser disruption and lowest level of dye uptake. Significantly, more rapid dye uptake and a higher total level of dye uptake occurred in six of the seven tested cancer cell lines (p < 0.05) as well as the immortalized cell line (p < 0.001). This difference in sensitivity was also observed when a viability assay was performed one day after plasma membrane permeabilization by electroporation. Viability in the primary normal cell line (98 % viable cells) was higher than in the three tested cancer cell lines (81-88 % viable cells). These data suggest more effective membrane repair in normal, primary cells and supplement previous explanations why electroporation-based therapies and other therapies permeabilizing the plasma membrane are more effective on malignant cells compared to normal cells in cancer treatment.


Assuntos
Membrana Celular/fisiologia , Regeneração , Linhagem Celular , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular , Sobrevivência Celular , Eletroquimioterapia , Eletroporação , Humanos , Melanoma/patologia , Melanoma/terapia
5.
Environ Sci Technol ; 50(10): 5294-304, 2016 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-27120978

RESUMO

The presence of synthetic glucocorticoids within the aquatic environment has been highlighted as a potential environmental concern as they may mimic the role of endogenous glucocorticoids during vertebrate ontogeny. Prednisolone is a commonly prescribed synthetic glucocorticoid which has been repeatedly detected in the environment. This study investigated the impact of environmentally relevant concentrations of prednisolone (0.1, 1, and 10 µg/L) during zebrafish embryogenesis using physiological and behavioral end points which are known to be mediated by endogenous glucocorticoids. The frequency of spontaneous muscle contractions (24 hpf) was significantly reduced by prednisolone and 0.1 µg/L increased the distance embryos swam in response to a mechanosensory stimulus (48 hpf). The percentage of embryos hatched significantly increased following prednisolone treatment (1 and 10 µg/L), while growth and mortality were unaffected. The onset of heart contraction was differentially affected by prednisolone while heart rate and oxygen consumption both increased significantly throughout embryogenesis. No substantial effect on the axial musculature was observed. Morphological changes to the lower jaw were detected at 96 hpf in response to 1 µg/L of prednisolone. Several parameters of swim behavior were also significantly affected. Environmentally relevant concentrations of prednisolone therefore alter early zebrafish ontogeny and significantly affect embryo behavior.


Assuntos
Prednisolona , Peixe-Zebra , Animais , Embrião não Mamífero/efeitos dos fármacos , Desenvolvimento Embrionário/efeitos dos fármacos , Glucocorticoides
6.
J Lipid Res ; 54(3): 581-591, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23288946

RESUMO

Plasma membrane disruptions occur in mechanically active tissues such as the epidermis and can lead to cell death if the damage remains unrepaired. Repair occurs through fusion of vesicle patches to the damaged membrane region. The enzyme phospholipase D (PLD) is involved in membrane traffickiing; therefore, the role of PLD in membrane repair was investigated. Generation of membrane disruptions by lifting epidermal keratinocytes from the substratum induced PLD activation, whereas removal of cells from the substratum via trypsinization had no effect. Pretreatment with 1,25-dihydroxyvitamin D3, previously shown to increase PLD1 expression and activity, had no effect on, and a PLD2-selective (but not a PLD1-selective) inhibitor decreased, cell lifting-induced PLD activation, suggesting PLD2 as the isoform activated. PLD2 interacts functionally with the glycerol channel aquaporin-3 (AQP3) to produce phosphatidylglycerol (PG); however, wounding resulted in decreased PG production, suggesting a potential PG deficiency in wounded cells. Cell lifting-induced PLD activation was transient, consistent with a possible role in membrane repair, and PLD inhibitors inhibited membrane resealing upon laser injury. In an in vivo full-thickness mouse skin wound model, PG accelerated wound healing. These results suggest that PLD and the PLD2/AQP3 signaling module may be involved in membrane repair and wound healing.


Assuntos
Queratinócitos/metabolismo , Fosfolipase D/metabolismo , Animais , Aquaporina 3/metabolismo , Calcitriol/farmacologia , Células Cultivadas , Ativação Enzimática/efeitos dos fármacos , Feminino , Masculino , Camundongos , Fosfatidilgliceróis/metabolismo , Cicatrização/efeitos dos fármacos
7.
Proc Natl Acad Sci U S A ; 106(31): 12573-9, 2009 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-19633189

RESUMO

Skeletal muscle basal lamina is linked to the sarcolemma through transmembrane receptors, including integrins and dystroglycan. The function of dystroglycan relies critically on posttranslational glycosylation, a common target shared by a genetically heterogeneous group of muscular dystrophies characterized by alpha-dystroglycan hypoglycosylation. Here we show that both dystroglycan and integrin alpha7 contribute to force-production of muscles, but that only disruption of dystroglycan causes detachment of the basal lamina from the sarcolemma and renders muscle prone to contraction-induced injury. These phenotypes of dystroglycan-null muscles are recapitulated by Large(myd) muscles, which have an intact dystrophin-glycoprotein complex and lack only the laminin globular domain-binding motif on alpha-dystroglycan. Compromised sarcolemmal integrity is directly shown in Large(myd) muscles and similarly in normal muscles when arenaviruses compete with matrix proteins for binding alpha-dystroglycan. These data provide direct mechanistic insight into how the dystroglycan-linked basal lamina contributes to the maintenance of sarcolemmal integrity and protects muscles from damage.


Assuntos
Membrana Basal/fisiologia , Distroglicanas/fisiologia , Laminina/fisiologia , Sarcolema/fisiologia , Animais , Sítios de Ligação , Distroglicanas/química , Glicosilação , Integrinas/fisiologia , Laminina/química , Vírus da Coriomeningite Linfocítica , Camundongos , Distrofia Muscular Animal/etiologia
8.
Int J Mol Sci ; 13(8): 10176-10192, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22949854

RESUMO

Helicobacter pylori (H. pylori), the human stomach pathogen, lives on the inner surface of the stomach and causes chronic gastritis, peptic ulcer, and gastric cancer. Plasma membrane repair response is a matter of life and death for human cells against physical and biological damage. We here test the hypothesis that H. pylori also causes plasma membrane disruption injury, and that not only a membrane repair response but also a cell proliferation response are thereby activated. Vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA) have been considered to be major H. pylori virulence factors. Gastric cancer cells were infected with H. pylori wild type (vacA+/cagA+), single mutant (ΔvacA or ΔcagA) or double mutant (ΔvacA/ΔcagA) strains and plasma membrane disruption events and consequent activation of membrane repair components monitored. H. pylori disrupts the host cell plasma membrane, allowing localized dye and extracellular Ca(2+) influx. Ca(2+)-triggered members of the annexin family, A1 and A4, translocate, in response to injury, to the plasma membrane, and cell surface expression of an exocytotic maker of repair, LAMP-2, increases. Additional forms of plasma membrane disruption, unrelated to H. pylori exposure, also promote host cell proliferation. We propose that H. pylori activation of a plasma membrane repair is pro-proliferative. This study might therefore provide new insight into potential mechanisms of H. pylori-induced gastric carcinogenesis.


Assuntos
Adenocarcinoma/patologia , Membrana Celular/patologia , Proliferação de Células , Infecções por Helicobacter/patologia , Helicobacter pylori/patogenicidade , Neoplasias Gástricas/patologia , Adenocarcinoma/microbiologia , Antígenos de Bactérias/genética , Antígenos de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Western Blotting , Cálcio/metabolismo , Citometria de Fluxo , Infecções por Helicobacter/microbiologia , Humanos , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Neoplasias Gástricas/microbiologia , Células Tumorais Cultivadas
9.
Biochim Biophys Acta ; 1793(12): 1886-93, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19781581

RESUMO

Mechanically damaged plasma membrane undergoes rapid calcium-dependent resealing that appears to depend, at least in part, on calpain-mediated cortical cytoskeletal remodeling. Cells null for Capns1, the non-catalytic small subunit present in both m- and mu-calpains, do not undergo calcium-mediated resealing. However, it is not known which of these calpains is needed for repair, or whether other major cytosolic proteinases may participate. Utilizing isozyme-selective siRNAs to decrease expression of Capn1 or Capn2, catalytic subunits of mu- and m-calpains, respectively, in a mouse embryonic fibroblast cell line, we now show that substantial loss of both activities is required to compromise calcium-mediated survival after cell scrape-damage. Using skeletal myotubes derived from Capn3-null mice, we were unable to demonstrate loss of sarcolemma resealing after needle scratch or laser damage. Isolated muscle fibers from Capn3 knockout mice also efficiently repaired laser damage. Employing either a cell line expressing a temperature sensitive E1 ubiquitin ligase, or lactacystin, a specific proteasome inhibitor, it was not possible to demonstrate an effect of the proteasome on calcium-mediated survival after injury. Moreover, several cell-permeant caspase inhibitors were incapable of significantly decreasing survival or inhibiting membrane repair. Taken together with previous studies, the results show that m- or mu-calpain can facilitate repair of damaged plasma membrane. While there was no evidence for the involvement of calpain-3, the proteasome or caspases in early events of plasma membrane repair, our studies do not rule out their participation in downstream events that may link plasma membrane repair to adaptive remodeling after injury.


Assuntos
Cálcio/metabolismo , Calpaína/metabolismo , Caspases/metabolismo , Membrana Celular/enzimologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Animais , Calpaína/genética , Caspases/genética , Linhagem Celular , Membrana Celular/genética , Camundongos , Camundongos Knockout , Proteínas Musculares , Complexo de Endopeptidases do Proteassoma/genética
10.
J Clin Invest ; 117(7): 1805-13, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17607357

RESUMO

Dilated cardiomyopathy is a life-threatening syndrome that can arise from a myriad of causes, but predisposition toward this malady is inherited in many cases. A number of inherited forms of dilated cardiomyopathy arise from mutations in genes that encode proteins involved in linking the cytoskeleton to the extracellular matrix, and disruption of this link renders the cell membrane more susceptible to injury. Membrane repair is an important cellular mechanism that animal cells have developed to survive membrane disruption. We have previously shown that dysferlin deficiency leads to defective membrane resealing in skeletal muscle and muscle necrosis; however, the function of dysferlin in the heart remains to be determined. Here, we demonstrate that dysferlin is also involved in cardiomyocyte membrane repair and that dysferlin deficiency leads to cardiomyopathy. In particular, stress exercise disturbs left ventricular function in dysferlin-null mice and increases Evans blue dye uptake in dysferlin-deficient cardiomyocytes. Furthermore, a combined deficiency of dystrophin and dysferlin leads to early onset cardiomyopathy. Our results suggest that dysferlin-mediated membrane repair is important for maintaining membrane integrity of cardiomyocytes, particularly under conditions of mechanical stress. Thus, our study establishes what we believe is a novel mechanism underlying the cardiomyopathy that results from a defective membrane repair in the absence of dysferlin.


Assuntos
Distrofina/metabolismo , Ventrículos do Coração/metabolismo , Ventrículos do Coração/patologia , Proteínas de Membrana/metabolismo , Animais , Cardiomiopatias/genética , Cardiomiopatias/metabolismo , Cardiomiopatias/patologia , Disferlina , Distrofina/deficiência , Distrofina/genética , Ventrículos do Coração/lesões , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Membranas/metabolismo , Membranas/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Isquemia Miocárdica/metabolismo , Isquemia Miocárdica/patologia , Condicionamento Físico Animal , Cicatrização
11.
Aging Cell ; 19(1): e13056, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31743583

RESUMO

Transient plasma membrane disruptions (PMD) occur in osteocytes with in vitro and in vivo loading, initiating mechanotransduction. The goal here was to determine whether osteocyte PMD formation or repair is affected by aging. Osteocytes from old (24 months) mice developed fewer PMD (-76% females, -54% males) from fluid shear than young (3 months) mice, and old mice developed fewer osteocyte PMD (-51%) during treadmill running. This was due at least in part to decreased pericellular matrix production, as studies revealed that pericellular matrix is integral to formation of osteocyte PMD, and aged osteocytes produced less pericellular matrix (-55%). Surprisingly, osteocyte PMD repair rate was faster (+25% females, +26% males) in osteocytes from old mice, and calcium wave propagation to adjacent nonwounded osteocytes was blunted, consistent with impaired mechanotransduction downstream of PMD in osteocytes with fast PMD repair in previous studies. Inducing PMD via fluid flow in young osteocytes in the presence of oxidative stress decreased postwounding cell survival and promoted accelerated PMD repair in surviving cells, suggesting selective loss of slower-repairing osteocytes. Therefore, as oxidative stress increases during aging, slower-repairing osteocytes may be unable to successfully repair PMD, leading to slower-repairing osteocyte death in favor of faster-repairing osteocyte survival. Since PMD are an important initiator of mechanotransduction, age-related decreases in pericellular matrix and loss of slower-repairing osteocytes may impair the ability of bone to properly respond to mechanical loading with bone formation. These data suggest that PMD formation and repair mechanisms represent new targets for improving bone mechanosensitivity with aging.


Assuntos
Membrana Celular/metabolismo , Mecanotransdução Celular/fisiologia , Osteócitos/metabolismo , Envelhecimento , Animais , Feminino , Humanos , Masculino , Camundongos
12.
J Orthop Res ; 36(2): 653-662, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28755471

RESUMO

Osteocytes sense loading in bone, but their mechanosensation mechanisms remain poorly understood. Plasma membrane disruptions (PMD) develop with loading under physiological conditions in many cell types (e.g., myocytes, endothelial cells). These PMD foster molecular flux across cell membranes that promotes tissue adaptation, but this mechanosensation mechanism had not been explored in osteocytes. Our goal was to investigate whether PMD occur and initiate consequent mechanotransduction in osteocytes during physiological loading. We found that osteocytes experience PMD during in vitro (fluid flow) and in vivo (treadmill exercise) mechanical loading, in proportion to the level of stress experienced. In fluid flow studies, osteocyte PMD preferentially formed with rapid as compared to gradual application of loading. In treadmill studies, osteocyte PMD increased with loading in weight bearing locations (tibia), but this trend was not seen in non-weight bearing locations (skull). PMD initiated osteocyte mechanotransduction including calcium signaling and expression of c-fos, and repair rates of these PMD could be enhanced or inhibited pharmacologically to alter downstream mechanotransduction and osteocyte survival. PMD may represent a novel mechanosensation pathway in bone and a target for modifying skeletal adaptation signaling in osteocytes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:653-662, 2018.


Assuntos
Osso e Ossos/fisiologia , Mecanotransdução Celular , Osteócitos/fisiologia , Citoesqueleto de Actina/metabolismo , Animais , Apoptose , Cálcio/metabolismo , Linhagem Celular , Camundongos , Técnicas Analíticas Microfluídicas , Cultura Primária de Células , Estresse Mecânico , Suporte de Carga
13.
Bone ; 39(4): 845-53, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16750436

RESUMO

The mechanisms underlying age-related loss of muscle and bone tissue are poorly understood but are thought to involve changes in sex hormone status, physical activity, and circulating levels of inflammatory cytokines. This study attempts to develop an animal model useful for evaluating these mechanisms in vivo. Male C57BL/6 mice were included for study at 3, 6, 12, 18, 24, and 29 months of age. Endocortical mineralizing surface, serum leptin, body weight, and percentage of body fat all increased between 6 and 12 months of age as activity level declined. Serum levels of the inflammatory marker IL-6 increased significantly after 12 months of age, following the observed increase in body weight and percent body fat. Hindlimb muscle mass declined significantly between 18 and 24 months of age, both absolutely and relative to total body mass, with a further decline ( approximately 15%) between 24 and 29 months. Loss of muscle mass after 18 months of age was accompanied by a significant increase in bone resorption, as indicated by serum pyridinoline cross-links, and a significant decrease in fat mass, serum leptin, bone strength, bone mineral density, and vertical cage activity. No significant changes in serum testosterone with aging were detected in the mice, as levels were essentially constant between 6 and 29 months. Our data show that mice lose a significant amount of muscle and bone tissue with age, and this loss of musculoskeletal tissue is accompanied by a drop in serum leptin and preceded by a significant decrease in physical activity.


Assuntos
Osso e Ossos/fisiologia , Leptina/sangue , Atividade Motora/fisiologia , Músculo Esquelético/fisiologia , Fatores Etários , Animais , Fenômenos Biomecânicos , Glicemia/metabolismo , Composição Corporal/fisiologia , Índice de Massa Corporal , Peso Corporal/fisiologia , Densidade Óssea/fisiologia , Osso e Ossos/citologia , Osso e Ossos/metabolismo , Interleucina-6/sangue , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Modelos Animais , Contração Muscular/fisiologia , Músculo Esquelético/citologia , Osteocalcina/metabolismo , Tomografia Computadorizada por Raios X/métodos
14.
Environ Pollut ; 218: 981-987, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27614910

RESUMO

The development of the eye in vertebrates is dependent upon glucocorticoid signalling, however, specific components of the eye are sensitive to synthetic glucocorticoids. The presence of synthetic glucocorticoids within the aquatic environment may therefore have important consequences for fish, which are heavily reliant upon vision for mediating several key behaviours. The potential ethological impact of synthetic glucocorticoid oculotoxicity however has yet to be studied. Physiological and behavioural responses which are dependent upon vision were selected to investigate the possible toxicity of prednisolone, a commonly occurring synthetic glucocorticoid within the environment, during early life stages of zebrafish. Although exposure to prednisolone did not alter the morphology of the external eye, aggregation of melanin within the skin in response to increasing light levels was impeded and embryos exposed to prednisolone (10 µg/l) maintained a darkened phenotype. Exposure to prednisolone also increased the preference of embryos for a dark environment within a light dark box test in a concentration dependent manner. However the ability of embryos to detect motion appeared unaffected by prednisolone. Therefore, while significant effects were detected in several processes mediated by vision, changes occurred in a manner which suggest that vision was in itself unaffected by prednisolone. Neurological and endocrinological changes during early ontogeny are considered as likely candidates for future investigation.


Assuntos
Olho/embriologia , Melaninas/metabolismo , Prednisolona/toxicidade , Pigmentação da Pele/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Poluição da Água/efeitos adversos , Peixe-Zebra/embriologia , Animais , Olho/crescimento & desenvolvimento , Prednisolona/análise , Pele/embriologia , Poluentes Químicos da Água/análise , Peixe-Zebra/crescimento & desenvolvimento
15.
Free Radic Biol Med ; 84: 246-253, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25843658

RESUMO

Vitamin E (VE) deficiency results in pronounced muscle weakness and atrophy but the cell biological mechanism of the pathology is unknown. We previously showed that VE supplementation promotes membrane repair in cultured cells and that oxidants potently inhibit repair. Here we provide three independent lines of evidence that VE is required for skeletal muscle myocyte plasma membrane repair in vivo. We also show that when another lipid-directed antioxidant, glutathione peroxidase 4 (Gpx4), is genetically deleted in mouse embryonic fibroblasts, repair fails catastrophically, unless cells are supplemented with VE. We conclude that lipid-directed antioxidant activity provided by VE, and possibly also Gpx4, is an essential component of the membrane repair mechanism in skeletal muscle. This work explains why VE is essential to muscle health and identifies VE as a requisite component of the plasma membrane repair mechanism in vivo.


Assuntos
Antioxidantes/farmacologia , Membrana Celular/metabolismo , Músculo Esquelético/fisiologia , Vitamina E/farmacologia , Animais , Membrana Celular/efeitos dos fármacos , Células Cultivadas , Glutationa Peroxidase/metabolismo , Masculino , Camundongos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/citologia , Músculo Esquelético/efeitos dos fármacos , Fosfolipídeo Hidroperóxido Glutationa Peroxidase , Ratos Sprague-Dawley
16.
Surgery ; 133(5): 528-37, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12773981

RESUMO

BACKGROUND: Wound repair results from a series of highly orchestrated cellular and biochemical events, including increased synthesis of the bioregulatory molecule nitric oxide (NO). The goal of this work was to test the functional role of NO in promotion of vascular endothelial growth factor (VEGF) production and the vigorous granulation tissue formation characteristic of this wound model. METHODS: A ventral hernia, surgically created in the abdominal walls of 12 swine, was repaired with silicone sheeting and skin closure. An osmotic infusion pump, inserted in a remote subcutaneous pocket, delivered saline solution (n = 6) or the selective inducible NO synthase inhibitor N(6) (iminoethyl)-L-lysine (L-NIL; n = 6) into the wound environment. Granulation tissue thickness was determined with ultrasonography, and local wound perfusion was measured with laser Doppler analysis for 2 weeks. Fluid was aspirated serially from the wound compartment for measurement of nitrite/nitrate, VEGF, and transforming growth factor-beta(1)concentrations. On day 14, the animals were killed and the abdominal wall was harvested for immunohistochemical and molecular analysis. RESULTS: In animals that received saline solution, a nearly linear 4-fold increase in granulation tissue thickness was measured during the 14-day interval. In contrast, in animals that received L-NIL, day 14 granulation tissue thickness was essentially unchanged from the day 2 values of saline solution-treated animals. Moreover, in the L-NIL animals, ultrasonography was unable to resolve the angiogenic zone typical of controls, and correspondingly, wound vessel count and vascular surface area estimates derived from image analysis of histologic sections were 2-fold to 3-fold lower in the L-NIL animals compared with controls. Reductions in basal (2-fold) and heat-provoked (2.5-fold) wound perfusion were noted in L-NIL animals. Wound fluid nitrite/nitrate and VEGF levels were strikingly (4-fold and 5-fold, respectively) reduced in L-NIL animals on days 9 to 14. Immunochemistry results showed reduced VEGF protein content in granulation tissue and keratinocytes within the hyperproliferative epithelium at wound edge. Finally, transforming growth factor-beta(1)levels were unaffected by L-NIL treatment. CONCLUSION: VEGF production in granulation tissue is dependent on the presence of functionally active inducible NO synthase and hence, the production of NO. NO and VEGF are therefore defined as key regulators of granulation tissue formation.


Assuntos
Fatores de Crescimento Endotelial/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Tecido de Granulação/crescimento & desenvolvimento , Hérnia Ventral/fisiopatologia , Linfocinas/antagonistas & inibidores , Lisina/análogos & derivados , Lisina/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Cicatrização/fisiologia , Animais , Fatores de Crescimento Endotelial/metabolismo , Feminino , Tecido de Granulação/efeitos dos fármacos , Tecido de Granulação/patologia , Hérnia Ventral/metabolismo , Hérnia Ventral/patologia , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Linfocinas/metabolismo , Neovascularização Fisiológica/efeitos dos fármacos , Óxido Nítrico Sintase Tipo II , Fluxo Sanguíneo Regional/efeitos dos fármacos , Suínos , Fator A de Crescimento do Endotélio Vascular , Fatores de Crescimento do Endotélio Vascular , Cicatrização/efeitos dos fármacos
17.
Curr Biol ; 24(9): R370-2, 2014 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-24801189

RESUMO

Calcium entry through a plasma membrane defect leads to the local recruitment of endosomal complex required for transport (ESCRT) proteins. These proteins are hypothesized to drive an outward bending of the affected plasma membrane, forming a small bud that is then shed from the cell, along with the troublesome defect.


Assuntos
Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Humanos
18.
Aquat Toxicol ; 152: 318-23, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24813264

RESUMO

The unique physicochemistry and potential toxicity of manufactured nanoparticles (NPs) requires innovative approaches for the assessment of toxicity to aquatic organisms. Here, the toxicity of Cu-NPs, Ag-NPs and TiO2-NPs on the lateral line system of free-swimming zebrafish embryos was investigated and compared to appropriate metal salts or bulk material controls. Fish were exposed for 4h at 96-h post-fertilization. Metal salt (CuSO4 and AgNO3) controls reduced the number of functional lateral line neuromasts (LLN) to <5% of unexposed controls, but no effect on LLN was observed for TiO2-NPs or Ag-NPs. Exposure to Cu-NPs caused only a 15% reduction in LLN. Performance of positive rheotaxis was reduced by Cu-NPs, Ag-NPs, and the metal salt controls. The data show that some metal NPs can affect LLN and fish behaviour (rheotaxis) important for survival, and that effects were different from those of comparable metal ion controls. Capsule: We demonstrate that behaviour is a particularly sensitive indicator of metal NP exposure in fish and highlight the interaction between behaviour and external tissue surfaces.


Assuntos
Comportamento Animal/efeitos dos fármacos , Sistema da Linha Lateral/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/embriologia , Animais , Embrião não Mamífero/efeitos dos fármacos
19.
Nat Commun ; 2: 597, 2011 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-22186893

RESUMO

Severe vitamin E deficiency results in lethal myopathy in animal models. Membrane repair is an important myocyte response to plasma membrane disruption injury as when repair fails, myocytes die and muscular dystrophy ensues. Here we show that supplementation of cultured cells with α-tocopherol, the most common form of vitamin E, promotes plasma membrane repair. Conversely, in the absence of α-tocopherol supplementation, exposure of cultured cells to an oxidant challenge strikingly inhibits repair. Comparative measurements reveal that, to promote repair, an anti-oxidant must associate with membranes, as α-tocopherol does, or be capable of α-tocopherol regeneration. Finally, we show that myocytes in intact muscle cannot repair membranes when exposed to an oxidant challenge, but show enhanced repair when supplemented with vitamin E. Our work suggests a novel biological function for vitamin E in promoting myocyte plasma membrane repair. We propose that this function is essential for maintenance of skeletal muscle homeostasis.


Assuntos
Membrana Celular/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/metabolismo , Mioblastos/metabolismo , Deficiência de Vitamina E/sangue , Animais , Membrana Celular/fisiologia , Relação Dose-Resposta a Droga , Glucose/efeitos adversos , Células HeLa , Homeostase , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Microscopia de Fluorescência , Fibras Musculares Esqueléticas/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Mioblastos/citologia , Mioblastos/efeitos dos fármacos , Estresse Oxidativo , Cicatrização/efeitos dos fármacos , alfa-Tocoferol/sangue , alfa-Tocoferol/farmacologia
20.
Diabetes ; 60(11): 3034-43, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21940783

RESUMO

OBJECTIVE: Skeletal muscle myopathy is a common diabetes complication. One possible cause of myopathy is myocyte failure to repair contraction-generated plasma membrane injuries. Here, we test the hypothesis that diabetes induces a repair defect in skeletal muscle myocytes. RESEARCH DESIGN AND METHODS: Myocytes in intact muscle from type 1 (INS2(Akita+/-)) and type 2 (db/db) diabetic mice were injured with a laser and dye uptake imaged confocally to test repair efficiency. Membrane repair defects were also assessed in diabetic mice after downhill running, which induces myocyte plasma membrane disruption injuries in vivo. A cell culture model was used to investigate the role of advanced glycation end products (AGEs) and the receptor for AGE (RAGE) in development of this repair defect. RESULTS: Diabetic myocytes displayed significantly more dye influx after laser injury than controls, indicating a repair deficiency. Downhill running also resulted in a higher level of repair failure in diabetic mice. This repair defect was mimicked in cultured cells by prolonged exposure to high glucose. Inhibition of the formation of AGE eliminated this glucose-induced repair defect. However, a repair defect could be induced, in the absence of high glucose, by enhancing AGE binding to RAGE, or simply by increasing cell exposure to AGE. CONCLUSIONS: Because one consequence of repair failure is rapid cell death (via necrosis), our demonstration that repair fails in diabetes suggests a new mechanism by which myopathy develops in diabetes.


Assuntos
Membrana Celular/metabolismo , Diabetes Mellitus Tipo 1/complicações , Diabetes Mellitus Tipo 2/complicações , Fibras Musculares Esqueléticas/metabolismo , Doenças Musculares/metabolismo , Animais , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Membrana Celular/efeitos da radiação , Membrana Celular/ultraestrutura , Células Cultivadas , Corantes Fluorescentes/metabolismo , Corantes Fluorescentes/toxicidade , Produtos Finais de Glicação Avançada/efeitos adversos , Produtos Finais de Glicação Avançada/antagonistas & inibidores , Produtos Finais de Glicação Avançada/metabolismo , Hiperglicemia/metabolismo , Lasers/efeitos adversos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Atividade Motora , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos da radiação , Fibras Musculares Esqueléticas/ultraestrutura , Doenças Musculares/patologia , Mioblastos Esqueléticos/metabolismo , Necrose , Receptor para Produtos Finais de Glicação Avançada , Receptores Imunológicos/metabolismo
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