ORCID Profile
0000-0001-5716-0783
Current Organisation
Deakin University
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Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.BIOMATERIALS.2015.02.086
Abstract: Lubricin is a glycoprotein found in articular joints which has been recognized as being an important biological boundary lubricant molecule. Besides providing lubrication, we demonstrate, using a quartz crystal microbalance, that lubricin also exhibits anti-adhesive properties and is highly effective at preventing the non-specific adsorption of representative globular proteins and constituents of blood plasma. This impressive anti-adhesive property, combined with lubricin's ability to readily self-assemble to form dense, highly stable telechelic polymer brush layers on virtually any substrates, and its innate biocompatibility, makes it an attractive candidate for anti-adhesive and anti-fouling coatings. We show that coatings of lubricin protein are as effective as, or better than, self-assembled monolayers of polyethylene glycol over a wide range of pH and that this provides a simple, versatile, highly stable, and highly effective method of controlling unwanted adhesion to surfaces.
Publisher: Elsevier BV
Date: 02-2001
DOI: 10.1046/J.1432-0436.2001.067001041.X
Abstract: The human breast contains two epithelial lineages, luminal epithelial and myoepithelial. Specific patterns of expression of intermediate filaments have previously been demonstrated in the resting breast. To determine how terminal differentiation and lactation influenced expression of intermediate filaments in breast epithelial cells, we used Western blot analysis to measure the levels of vimentin, alpha-smooth muscle actin, keratin 14, and keratin 18 in the resting and lactating breast. Confocal immunofluorescence was used to determine the subcellular site of localization of the intermediate filaments. Vimentin was localised to myoepithelial cells in both the resting and lactating gland. There was a four-fold increase in vimentin protein levels in lactating tissue relative to resting tissue, and this may be related to increased cellular activity of the myoepithelial cells which surround secretory alveoli. Alpha-smooth muscle actin and keratin 14 were detected in myoepithelial cells, and similar levels of expression were found in lactating and resting tissue. In the resting breast, keratin 18 and keratin 8 were detected in luminal epithelial cells in a filamentous form, whereas in lactating tissue it was present in a punctate form in luminal cells and also seen as granules in the lumen of alveoli. Our results indicate that intermediate filament expression patterns are altered in the lactating human breast, and this may reflect their role in the fully functional gland.
Publisher: Wiley
Date: 2014
DOI: 10.1002/PHY2.195
Publisher: American Chemical Society (ACS)
Date: 05-02-2021
DOI: 10.26434/CHEMRXIV.13719649
Abstract: a /a High strength steel in marine environments suffers from severe corrosion susceptibility and the presence of bacteria can exacerbate the effect, accelerating degradation via microbiologically influenced corrosion (MIC). Here we propose a novel approach to MIC inhibition by designing a system capable of limiting the effects of both bacteria growth and corrosion. The combination of a newly synthesised compound, cetrimonium 4-hydroxycinnamate, with lanthanum 4-hydroxycinnamate was the only system tested to date that could both inhibit abiotic corrosion in artificial seawater and minimise bacteria consortium densities over an exposure period of 24 hours. The electrochemical data for the La+Cet mixture demonstrated the significant inhibition of both abiotic corrosion to a level similar to La(4OHCin) sub /sub , as well as the ability to reduce bacteria densities of single strains and a consortium. This is unlike the La+CetNal mixture which accelerated abiotic corrosion and the La+IMI which had an insignificant effect on microbial densities (Catubig et al. 2020). A compatible mixture of ionic inhibitors was achieved by using the same cinnamate anion. This mixture of Cet-4OHCin and La(4OHCin) sub /sub demonstrated significant abiotic corrosion inhibition and bacteria density reductions, making it a strong candidate as an MIC inhibitor system for 80HLES. The Cet-4OHCin compound and its mixture with La(4OHCin) sub /sub retained relatively low sensitivity towards skin and intestinal cells, making it a safer and more attractive alternative than other more hazardous corrosion inhibitor materials.
Publisher: MDPI AG
Date: 25-10-2011
DOI: 10.3390/NU3110910
Publisher: Oxford University Press (OUP)
Date: 19-06-2013
Abstract: Metal homoeostasis in cyanobacteria is based on uptake and export systems that are controlled by their own regulators. This study characterises the zinc uptake (Znu) system in Nostoc punctiforme. The system was found to comprise of three subunits in an ACB operon: a Zn(2+)-binding protein (ZnuA18), a transmembrane domain (ZnuB) and an ATPase (ZnuC). These proteins are encoded within the znu operon regulated by a zinc uptake transcription repressor (Zur). Interestingly, a second Zn(2+)-binding protein (ZnuA08) was also identified at a distal genomic location. Interactions between components of the ZnuACB system were investigated using knockouts of the in idual genes. The znuA08(-), znuA18(-), znuB(-) and znuC(-) mutants displayed overall reduced znuACB transcript levels, suggesting that all system components are required for normal expression of znu genes. Zinc uptake assays in the Zn(2+)-binding protein mutant strains showed that the disruption of znuA18 had a greater negative effect on zinc uptake than disruption of znuA08. Complementation studies in Escherichia coli indicated that both znuA08 and znuA18 were able to restore zinc uptake in a znuA(-) mutant, with znuA18 permitting the highest zinc uptake rate. The N. punctiforme zur was also able to complement the E. coli zur(-) mutant.
Publisher: Oxford University Press (OUP)
Date: 24-09-2015
DOI: 10.1111/JAM.12942
Abstract: To characterize genes involved in maintaining homeostatic levels of zinc in the cyanobacterium Nostoc punctiforme. Metal efflux transporters play a central role in maintaining homeostatic levels of trace elements such as zinc. Sequence analyses of the N. punctiforme genome identified two potential cation diffusion facilitator (CDF) metal efflux transporters, Npun_F0707 (Cdf31) and Npun_F1794 (Cdf33). Deletion of either Cdf31or Cdf33 resulted in increased zinc retention over 3 h. Interestingly, Cdf31(-) and Cdf33(-) mutants showed no change in sensitivity to zinc exposure in comparison with the wild type, suggesting some compensatory capacity for the loss of each other. Using qRT-PCR, a possible interaction was observed between the two cdf's, where the Cdf31(-) mutant had a more profound effect on cdf33 expression than Cdf33(-) did on cdf31. Over-expression of Cdf31 and Cdf33 in ZntA(-) - and ZitB(-) -deficient Escherichia coli revealed function similarities between the ZntA and ZitB of E. coli and the cyanobacterial transporters. The data presented shed light on the function of two important transporters that regulate zinc homeostasis in N. punctiforme. This study shows for the first time the functional characterization of two cyanobacterial zinc efflux proteins belonging to the CDF family.
Publisher: Springer Science and Business Media LLC
Date: 08-2003
DOI: 10.1007/S00439-003-0952-2
Abstract: Zinc deficiency, causing impaired growth and development, may have a nutritional or genetic basis. We investigated two cases of inherited zinc deficiency found in breast-fed neonates, caused by low levels of zinc in the maternal milk. This condition is different from acrodermatitis enteropathica but has similarities to the "lethal milk" mouse, where low levels of zinc in the milk of lactating dams leads to zinc deficiency in pups. The mouse disorder has been attributed to a defect in the ZnT4 gene. Little is known about the expression of the human orthologue, hZnT4 (Slc30A4). Sequence analysis of cDNA, real-time PCR and Western blot analysis of hZnT4, carried out on control cells and cells from unrelated mothers of two infants with zinc deficiency, showed no differences. The hZnT4 gene was highly expressed in mouthwash buccal cells compared with lymphoblasts and fibroblasts. The hZnT4 protein did not co-localise with intracellular free zinc pools, suggesting that hZnT4 is not involved in transport of zinc into vesicles destined for secretion into milk. This observation, combined with phenotypic differences between the "lethal milk" mouse and the human disorder, suggests that the "lethal milk" mouse is not the corresponding model for the human zinc deficiency condition.
Publisher: American Chemical Society (ACS)
Date: 05-02-2021
DOI: 10.26434/CHEMRXIV.13719649.V1
Abstract: High strength steel in marine environments suffers from severe corrosion susceptibility and the presence of bacteria can exacerbate the effect, accelerating degradation via microbiologically influenced corrosion (MIC). Here we propose a novel approach to MIC inhibition by designing a system capable of limiting the effects of both bacteria growth and corrosion. The combination of a newly synthesised compound, cetrimonium 4-hydroxycinnamate, with lanthanum 4-hydroxycinnamate was the only system tested to date that could both inhibit abiotic corrosion in artificial seawater and minimise bacteria consortium densities over an exposure period of 24 hours. The electrochemical data for the La+Cet mixture demonstrated the significant inhibition of both abiotic corrosion to a level similar to La(4OHCin) 3 , as well as the ability to reduce bacteria densities of single strains and a consortium. This is unlike the La+CetNal mixture which accelerated abiotic corrosion and the La+IMI which had an insignificant effect on microbial densities (Catubig et al. 2020). A compatible mixture of ionic inhibitors was achieved by using the same cinnamate anion. This mixture of Cet-4OHCin and La(4OHCin) 3 demonstrated significant abiotic corrosion inhibition and bacteria density reductions, making it a strong candidate as an MIC inhibitor system for 80HLES. The Cet-4OHCin compound and its mixture with La(4OHCin) 3 retained relatively low sensitivity towards skin and intestinal cells, making it a safer and more attractive alternative than other more hazardous corrosion inhibitor materials.
Publisher: Springer Science and Business Media LLC
Date: 17-05-2012
DOI: 10.1007/S10534-012-9556-4
Abstract: Trace metals are required for many cellular processes. The acquisition of trace elements from the environment includes a rapid adsorption of metals to the cell surface, followed by a slower internalization. We investigated the uptake of the trace elements Co(2+), Cu(2+), Mn(2+), Ni(2+), and Zn(2+) and the non-essential alent cation Cd(2+) in the cyanobacterium Nostoc punctiforme. For each metal, a dose response study based on cell viability showed that the highest non-toxic concentrations were: 0.5 μM Cd(2+), 2 μM Co(2+), 0.5 μM Cu(2+), 500 μM Mn(2+), 1 μM Ni(2+), and 18 μM Zn(2+). Cells exposed to these non-toxic concentrations with combinations of Zn(2+) and Cd(2+), Zn(2+) and Co(2+), Zn(2+) and Cu(2+) or Zn(2+) and Ni(2+), had reduced growth in comparison to controls. Cells exposed to metal combinations with the addition of 500 μM Mn(2+) showed similar growth compared to the untreated controls. Metal levels were measured after one and 72 h for whole cells and absorbed (EDTA-resistant) fractions and used to calculate differential uptake rates for each metal. The differences in binding and internalisation between different metals indicate different uptake processes exist for each metal. For each metal, competitive uptake experiments using (65)Zn showed that after 72 h of exposure Zn(2+) uptake was reduced by most metals particularly 0.5 μM Cd(2+), while 2 μM Co(2+) increased Zn(2+) uptake. This study demonstrates that N. punctiforme discriminates between different metals and favourably substitutes their uptake to avoid the toxic effects of particular metals.
Publisher: Springer Science and Business Media LLC
Date: 29-08-2015
Publisher: Springer Science and Business Media LLC
Date: 30-06-2013
DOI: 10.1007/S00253-013-5047-Y
Abstract: The ZIP family of metal transporters is involved in the transport of Zn(2+) and other metal cations from the extracellular environment and/or organelles into the cytoplasm of prokaryotes, eukaryotes and archaeotes. In the present study, we identified twin ZIP transporters, Zip11 (Npun_F3111) and Zip63 (Npun_F2202) encoded within the genome of the filamentous cyanobacterium, Nostoc punctiforme PCC73120. Sequence-based analyses and structural predictions confirmed that these cyanobacterial transporters belong to the SLC39 subfamily of metal transporters. Quantitative real-time (QRT)-PCR analyses suggested that the enzymes encoded by zip11 and zip63 have a broad allocrite range that includes zinc as well as cadmium, cobalt, copper, manganese and nickel. Inactivation of either zip11 or zip63 via insertional mutagenesis in N. punctiforme resulted in reduced expression of both genes, highlighting a possible co-regulation mechanism. Uptake experiments using (65)Zn demonstrated that both zip mutants had diminished zinc uptake capacity, with the deletion of zip11 resulting in the greatest overall reduction in (65)Zn uptake. Over-expression of Zip11 and Zip63 in an E. coli mutant strain (ZupT736::kan) restored alent metal cation uptake, providing further evidence that these transporters are involved in Zn uptake in N. punctiforme. Our findings show the functional role of these twin metal uptake transporters in N. punctiforme, which are independently expressed in the presence of an array of metals. Both Zip11 and Zip63 are required for the maintenance of homeostatic levels of intracellular zinc N. punctiforme, although Zip11 appears to be the primary zinc transporter in this cyanobacterium, both ZIP's may be part of a larger metal uptake system with shared regulatory elements.
Publisher: Wiley
Date: 16-12-2010
DOI: 10.1016/J.FEBSLET.2009.12.013
Abstract: Docosahexaenoic acid (DHA) is the major polyunsaturated fatty acid in neuronal cell membranes. We hypothesize that DHA induces a decrease in neuronal cell death through reduced ZnT3 expression and zinc uptake. Exposure of M17 cells to DHA-deficient medium increased the levels of active caspase-3, relative to levels in DHA-replete cells, confirming the adverse effects of DHA deficiency in promoting neuronal cell death. In DHA-treated M17 cells, zinc uptake was 65% less and ZnT3 mRNA and protein levels were reduced in comparison with DHA-depleted cells. We propose that the neuroprotective function of DHA is exerted through a reduction in cellular zinc levels that in turn inhibits apoptosis.
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.ABB.2016.06.011
Abstract: Zinc is essential for a wide variety of cellular processes in all cells. It is a critical dietary nutrient, particularly in the early stages of life. In the early neonatal period, adequate sources of zinc can be obtained from breast milk. In rare circumstances, the mammary gland produces zinc deficient milk that is potentially lethal for exclusively breast-fed infants. This can be overcome by zinc supplementation to the infant. Alterations to key zinc transporters provide insights into the mechanisms of cellular zinc homeostasis. The bioavailability of zinc in food depends on the presence of constituents that may complex zinc. In many countries, zinc deficiency is a major health issue due to poor nourishment. Young children are particularly affected. Zinc deficiency can impair immune function and contributes to the global burden of infectious diseases including diarrhoea, pneumonia and malaria. Furthermore, zinc deficiency may extend its influence across generations by inducing epigenetic effects that alter the expression of genes. This review discusses the significance of adequate zinc nutrition in infants, factors that influence zinc nutrition, the consequences of zinc deficiency, including its contribution to the global burden of disease, and addresses some of the knowledge gaps in zinc biology.
Publisher: Oxford University Press (OUP)
Date: 2016
DOI: 10.1039/C6MT00086J
Abstract: Ceruloplasmin (Cp) is a multicopper ferroxidase that is considered to be an important source of copper in milk for normal neonatal development. We investigated the expression, subcellular localization and secretion of Cp in PMC42-LA cell culture models representative of resting, lactating and suckled human mammary epithelia. Both secreted Cp (sCp) and plasma membrane associated glycosylphosphatidylinositol-linked Cp (GPI-Cp) were expressed in PMC42-LA cells. In all three epithelial models (resting, lactating and suckled), the expression and secretion of copper-bound, ferroxidase active, Cp (holo-Cp) was dependent on media copper concentration. In low copper (bathocuproinedisulphonic acid/d-penicillamine treated models) there was greater than a 2-fold decrease in holo-Cp expression and secretion, which was mirrored by a 2-fold increase in the expression and secretion of copper-free Cp protein (apo-Cp). Cell surface biotinylation studies revealed that the state of PMC42-LA cell differentiation (functionality), and the level of extracellular copper, had no significant effect on the level of plasma membrane bound GPI-Cp. Quantitative real time PCR analyses determined that there was no significant (P > 0.05) difference in Cp mRNA levels across all copper conditions investigated (0, 5, 50 μM). However, there was a significant (P < 0.05) increase (∼2-fold) in Cp mRNA in both the lactating and suckled models in comparison to the resting model. Furthermore, the Cp mRNA increase in response to PMC42-LA differentiation corresponded with more secreted Cp protein, both apo and holo forms, indicating a link between function and Cp requirement. Our results provide significant insight on the regulation of Cp expression and secretion in lactation and copper incorporation into milk.
Publisher: Portland Press Ltd.
Date: 12-02-2007
DOI: 10.1042/BJ20061099
Abstract: Copper deficiency during pregnancy results in early embryonic death and foetal structural abnormalities including skeletal, pulmonary and cardiovascular defects. During pregnancy, copper is transported from the maternal circulation to the foetus by mechanisms which have not been clearly elucidated. Two copper-transporting ATPases, Menkes (ATP7A MNK) and Wilson (ATP7B WND), are expressed in the placenta and both are involved in placental copper transport, as copper accumulates in the placenta in both Menkes and Wilson disease. The regulatory mechanisms of MNK and WND and their exact role in the placenta are unknown. Using a differentiated polarized Jeg-3 cell culture model of placental trophoblasts, MNK and WND were shown to be expressed within these cells. Distinct roles for MNK and WND are suggested on the basis of their opposing responses to insulin. Insulin and oestrogen increased both MNK mRNA and protein levels, altered the localization of MNK towards the basolateral membrane in a copper-independent manner, and increased the transport of copper across this membrane. In contrast, levels of WND were decreased in response to insulin, and the protein was located in a tight perinuclear region, with a corresponding decrease in copper efflux across the apical membrane. These results are consistent with a model of copper transport in the placenta in which MNK delivers copper to the foetus and WND returns excess copper to the maternal circulation. Insulin and oestrogen stimulate copper transport to the foetus by increasing the expression of MNK and reducing the expression of WND. These data show for the first time that MNK and WND are differentially regulated by the hormones insulin and oestrogen in human placental cells.
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.JNUTBIO.2013.11.011
Abstract: Adequate amounts of copper in milk are critical for normal neonatal development, however the mechanisms regulating copper supply to milk have not been clearly defined. PMC42-LA cell cultures representative of resting, lactating and suckled mammary epithelia were used to investigate the regulation of the copper uptake protein, CTR1. Both the degree of mammary epithelial differentiation (functionality) and extracellular copper concentration greatly impacted upon CTR1 expression and its plasma membrane association. In all three models (resting, lactating and suckling) there was an inverse correlation between extracellular copper concentration and the level of CTR1. Cell surface biotinylation studies demonstrated that as extracellular copper concentration increased membrane associated CTR1 was reduced. There was a significant increase in CTR1 expression (total and membrane associated) in the suckled gland model in comparison to the resting gland model, across all copper concentrations investigated (0-50 μM). Regulation of CTR1 expression was entirely post-translational, as quantitative real-time PCR analyses showed no change to CTR1 mRNA between all models and culture conditions. X-ray fluorescence microscopy on the differentiated PMC42-LA models revealed that organoid structures distinctively accumulated copper. Furthermore, as PMC42-LA cell cultures became progressively more specialised, successively more copper accumulated in organoids (resting<lactating<suckling), indicating a link between function and copper requirement. Based on previous data showing a function for CTR1 in copper uptake, we have concluded that under the influence of hormones and increased extracellular copper levels, CTR1 participates in uptake of copper by mammary epithelial cells, as a prerequisite for secretion of copper into milk.
Publisher: Springer Science and Business Media LLC
Date: 20-08-2015
DOI: 10.1007/S00253-015-6922-5
Abstract: Analysis of cellular response to zinc exposure provides insights into how organisms maintain homeostatic levels of zinc that are essential, while avoiding potentially toxic cytosolic levels. Using the cyanobacterium Nostoc punctiforme as a model, qRT-PCR analyses established a profile of the changes in relative mRNA levels of the ZntA-like zinc efflux transporter NpunR4017 in response to extracellular zinc. In cells treated with 18 μM of zinc for 1 h, NpunR4017 mRNA levels increased by up to 1300 % above basal levels. The accumulation and retention of radiolabelled (65)Zn by NpunR4107-deficient and overexpressing strains were compared to wild-type levels. Disruption of NpunR4017 resulted in a significant increase in zinc accumulation up to 24 % greater than the wild type, while cells overexpressing NpunR4107 accumulated 22 % less than the wild type. Accumulation of (65)Zn in ZntA(-) Escherichia coli overexpressing NpunR4017 was reduced by up to 21 %, indicating the capacity for NpunR4017 to compensate for the loss of ZntA. These findings establish the newly identified NpunR4017 as a zinc efflux transporter and a key transporter for maintaining zinc homeostasis in N. punctiforme.
Publisher: The Endocrine Society
Date: 06-2016
DOI: 10.1210/JC.2015-4206
Abstract: Lifestyle factors mediate epigenetic changes that can cause chronic diseases. Although animal and laboratory studies link epigenetic changes to diabetes, epigenetic information in women with gestational diabetes (GDM) and type 2 diabetes is lacking. This study sought to measure epigenetic markers across pregnancy and early postpartum and identify markers that could be used as predictors for conversion from GDM to type 2 diabetes. Global histone H3 dimethylation was measured in white blood cells at three time points: 30 wk gestation, 8-10 wk postpartum, and 20 wk postpartum, from four groups of women with and without diabetes. A total of 39 participants (six to nine in each group) were recruited including: nondiabetic women women with GDM who developed postpartum type 2 diabetes women with GDM without postpartum type 2 diabetes and women with type 2 diabetes. Percentages of dimethylation of H3 histones relative to total H3 histone methylation were compared between diabetic/nondiabetic groups using appropriate comparative statistics. H3K27 dimethylation was 50-60% lower at 8-10 and 20 wk postpartum in women with GDM who developed type 2 diabetes, compared with nondiabetic women. H3K4 dimethylation was 75% lower at 8-10 wk postpartum in women with GDM who subsequently developed type 2 diabetes compared with women who had GDM who did not. The percentage of dimethylation of histones H3K27 and H3K4 varied with diabetic state and has the potential as a predictive tool to identify women who will convert from GDM to type 2 diabetes.
Publisher: No publisher found
Date: 2001
Publisher: Oxford University Press (OUP)
Date: 10-01-2012
Abstract: Copper-based compounds have been used as agricultural fungicides for many years. Their use in Australia is escalating with increase in the scale of planting and associated pest problems. The objective of this study was to identify viticulture activities associated with high exposure to foliage sprays. It would be determined if occupational exposure of vineyard workers to copper-based sprays was associated with raised body copper levels through analysis of saliva and buccal cells. The activities of six vineyard workers from four vineyards in the Yarra Valley Victoria, Australia, were monitored over a period of 2 years. During this period, workers carried out seasonal activities, including fungicide spraying, canopy management, and tractor operation. Saliva and buccal cells from workers were collected and analysed for copper levels that were then correlated with the different types of vineyard activity. The buccal cells of vineyard workers exposed to copper through seasonal activities including fungicide spraying, canopy management, and tractor operation contained copper levels of 0.87, 1.24, and 0.95 ng Cu per 10(6) cells, respectively. This was up to 10-fold higher than the copper levels in buccal cells from the control subjects (0.1 ng Cu per 10(6)). Copper levels in buccal cells from workers participating in other viticulture activities such as shoot thinning, bunch counting, and disbudding were not significantly different from those of control subjects. The levels of copper in saliva s les of both workers undertaking any vineyard activity and control subjects were below the level of detection. Seasonal activities undertaken in vineyards that involved direct contact with copper, in particular canopy management, fungicidal spraying, and tractor operation were associated with high copper levels in buccal cells of workers. This indicates that copper derived from copper-based fungicidal compounds is accumulated within body cells. The lack of detectable copper levels in saliva suggests that the route of transport of copper into buccal cells is not through saliva. The results indicate potential adverse health risks associated with use of copper fungicide. Recommendations are made in relation to the precautions that should be taken in relation to use of copper sprays and to validate buccal cells as an indicator of body copper status.
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.BMC.2008.02.053
Abstract: Resistance to kinase-targeted cancer drugs has recently been linked to a single point mutation in the ATP binding site of the kinase. In EGFR, the crucial Thr790 gatekeeper residue is mutated to a Met and prevents reversible ATP competitive inhibitors from binding. Irreversible 4-(phenylamino)quinazolines have been shown to overcome this drug resistance and are currently in clinical trials. In order to obtain a detailed structural understanding of how irreversible inhibitors overcome drug resistance, we used Src kinase as a model system for drug resistant EGFR-T790M. We report the first crystal structure of a drug resistant kinase in complex with an irreversible inhibitor. This 4-(phenylamino)quinazoline inhibits wild type and drug resistant EGFR in vitro at low nM concentrations. The co-crystal structure of drug resistant cSrc-T338M kinase domain provides the structural basis of this activity.
Publisher: Elsevier BV
Date: 08-2023
Publisher: SAGE Publications
Date: 10-12-2008
Abstract: A role for the copper transporter, ATP7B, in secretion of copper from the human breast into milk has previously not been reported, although it is known that the murine ortholog of ATP7B facilitates copper secretion in the mouse mammary gland. We show here that ATP7B is expressed in luminal epithelial cells in both the resting and lactating human breast, where it has a perinuclear localization in resting epithelial cells and a diffuse location in lactating tissue. ATP7B protein was present in a different subset of vesicles from those containing milk proteins and did not overlap with Menkes ATPase, ATP-7A, except in the perinuclear region of cells. In the cultured human mammary line, PMC42-LA, treatment with lactational hormones induced a redistribution of ATP7B from a perinuclear region to a region adjacent, but not coincident with, the apical plasma membrane. Trafficking of ATP7B was copper dependent, suggesting that the hormone-induced redistribution of ATP7A was mediated through an increase in intracellular copper. Radioactive copper ( 64 Cu) studies using polarized PMC42-LA cells that overexpressed mAtp7B protein showed that this transporter facilitates copper efflux from the apical surface of the cells. In summary, our results are consistent with an important function of ATP7B in the secretion of copper from the human mammary gland.
Publisher: American Physiological Society
Date: 09-2008
DOI: 10.1152/AJPCELL.00029.2008
Abstract: Ionic copper entering blood plasma binds tightly to albumin and the macroglobulin transcuprein. It then goes primarily to the liver and kidney except in lactation, where a large portion goes directly to the mammary gland. Little is known about how this copper is taken up from these plasma proteins. To examine this, the kinetics of uptake from purified human albumin and α 2 -macroglobulin, and the effects of inhibitors, were measured using human hepatic (HepG2) and mammary epithelial (PMC42) cell lines. At physiological concentrations (3–6 μM), both cell types took up copper from these proteins independently and at rates similar to each other and to those for Cu-dihistidine or Cu-nitrilotriacetate (NTA). Uptakes from α 2 -macroglobulin indicated a single saturable system in each cell type, but with different kinetics, and 65–80% inhibition by Ag(I) in HepG2 cells but not PMC42 cells. Uptake kinetics for Cu-albumin were more complex and also differed with cell type (as was the case for Cu-histidine and NTA), and there was little or no inhibition by Ag(I). High Fe(II) concentrations (100–500 μM) inhibited copper uptake from albumin by 20–30% in both cell types and that from α 2 -macroglobulin by 0–30%, and there was no inhibition of the latter by Mn(II) or Zn(II). We conclude that the proteins mainly responsible for the plasma-exchangeable copper pool deliver the metal to mammalian cells efficiently and by several different mechanisms. α 2 -Macroglobulin delivers it primarily to copper transporter 1 in hepatic cells but not mammary epithelial cells, and additional as-yet-unidentified copper transporters or systems for uptake from these proteins remain to be identified.
Publisher: Wiley
Date: 11-2011
Publisher: American Society for Microbiology
Date: 02-2009
DOI: 10.1128/AEM.02481-08
Abstract: Zinc homeostasis was investigated in Nostoc punctiforme . Cell tolerance to Zn 2+ over 14 days showed that ZnCl 2 levels above 22 μM significantly reduced cell viability. After 3 days in 22 μM ZnCl 2 , ca. 12% of the Zn 2+ was in an EDTA-resistant component, suggesting an intracellular localization. Zinquin fluorescence was detected within cells exposed to concentrations up to 37 μM relative to 0 μM treatment. Radiolabeled 65 Zn showed Zn 2+ uptake increased over a 3-day period, while efflux occurred more rapidly within a 3-h time period. Four putative genes involved in Zn 2+ uptake and efflux in N. punctiforme were identified: (i) the predicted Co/Zn/Cd cation transporter, putative CDF (ii) the predicted alent heavy-metal cation transporter, putative Zip (iii) the ATPase component and Fe/Zn uptake regulation protein, putative Fur and (iv) an ABC-type Mn/Zn transport system, putative zinc ZnuC, ZnuABC system component. Quantitative real-time PCR indicated the responsiveness of all four genes to 22 μM ZnCl 2 within 3 h, followed by a reduction to below basal levels after 24 h by putative ZIP, ZnuC, and Fur and a reduction to below basal level after 72 h by putative CDF efflux gene. These results demonstrate differential regulation of zinc transporters over time, indicating a role for them in zinc homeostasis in N. punctiforme .
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/EN14078
Abstract: Environmental context Soils contaminated with metals can pose both environmental and human health risks. This study showed that a common crop vegetable grown in the presence of cadmium and zinc readily accumulated these metals, and thus could be a source of toxicity when eaten. The work highlights potential health risks from consuming crops grown on contaminated soils. Abstract Ingestion of plants grown in heavy metal contaminated soils can cause toxicity because of metal accumulation. We compared Cd and Zn levels in Brassica rapa, a widely grown crop vegetable, with that of the hyperaccumulator Solanum nigrum L. Solanum nigrum contained 4 times more Zn and 12 times more Cd than B. rapa, relative to dry mass. In S. nigrum Cd and Zn preferentially accumulated in the roots whereas in B. rapa Cd and Zn were concentrated more in the shoots than in the roots. The different distribution of Cd and Zn in B. rapa and S. nigrum suggests the presence of distinct metal uptake mechanisms. We correlated plant metal content with the expression of a conserved putative natural resistance-associated macrophage protein (NRAMP) metal transporter in both plants. Treatment of both plants with either Cd or Zn increased expression of the NRAMP, with expression levels being higher in the roots than in the shoots. These findings provide insights into the molecular mechanisms of heavy metal processing by S. nigrum L. and the crop vegetable B. rapa that could assist in application of these plants for phytoremediation. These investigations also highlight potential health risks associated with the consumption of crops grown on contaminated soils.
Publisher: CRC Press
Date: 03-2013
DOI: 10.1201/B13853-14
Publisher: Wiley
Date: 10-2002
Publisher: Springer Science and Business Media LLC
Date: 03-2006
DOI: 10.1007/BF02829935
Publisher: Portland Press Ltd.
Date: 15-11-1997
DOI: 10.1042/BJ3280237
Abstract: Two P-type ATPases, MNK and WND were recently shown to be defective in the human disorders of copper transport, Menkes disease and Wilson disease respectively. These proteins are important in copper homeostasis but their full physiological function has not been established. This study uses the human breast carcinoma line, PMC42, to investigate copper transport in the mammary gland. Northern blot analysis indicated that both MNK and WND mRNA are expressed in these cells. Western blot analysis with an MNK-specific antibody demonstrated a band of approx. 178 kDa, close to the expected size of 163 kDa. Treatment of PMC42 cells with lactational hormones (oestrogen and progesterone for 3 days followed by dexamethasone, insulin and prolactin for a further 3 days) did not produce an obvious increase in MNK expression as measured by Northern and Western blots. By using indirect immunofluorescence with the MNK antibody, the intracellular distribution of MNK was found to be predominantly perinuclear, consistent with Golgi localization. Punctate staining was also seen in a smaller proportion of cells, suggesting that some MNK is associated with endosomes. Treatment of PMC42 cells with lactational hormones increased the intensity of the perinuclear and punctate fluorescence. Exposure of cells to 100 mM copper resulted in the dispersion of the fluorescence towards the periphery of the cell. The results suggest a role for MNK in the secretion of copper into milk and that PMC42 cells are a valuable model for investigating the detailed cellular function of MNK and WND.
Publisher: Wiley
Date: 07-08-2007
Abstract: The cellular effects of biodiesel emissions particulate matter (BDEP) and petroleum diesel emissions particulate matter (PDEP) were compared using a human airway cell line, A549. At concentrations of 25 microg/ml, diesel particulate matter induced the formation of multinucleate cells. In cells treated with a mixture of 80% PDEP:20% BDEP, 52% of cells were multinucleate cells compared with only 16% of cells treated with 20% PDEP:80% BDEP with a background multinucleate rate of 7%. These results demonstrate a causal relation between the formation of multinucleate cells and exposure to exhaust particulate matter, in particular diesel exhaust. Exposure of A549 cells to PDEP induced apoptosis, seen by active caspase-3 expression and the presence of cleaved pancytokeratin. PDEP exhaust was a much stronger inducer of cellular death through apoptosis than BDEP. There was an eightfold increase in the expression of SLC30A3 (zinc transporter-3 or ZnT3) in cells exposed to 80% PDEP:20% BDEP compared to untreated cells. The increase in ZnT3 expression seen in apoptotic cells following PDEP suggests a role for this zinc transporter in the apoptotic pathway, possibly through controlling zinc fluxes. As exposure to diesel exhaust particles is associated with asthma and apoptosis in airway cells, diesel exhaust particles may directly contribute to asthma by inducing epithelial cell death through apoptotic pathway.
Publisher: SAGE Publications
Date: 12-1999
DOI: 10.1177/002215549904701207
Abstract: The Menkes copper ATPase (MNK) is a copper efflux ATPase that is involved in copper homeostasis. Little is known about the intracellular localization and cell-specific function of the MNK in human tissues. To investigate a possible role for this protein in lactation, we measured its expression in sections of tissue from nonlactating and lactating human breast. Western blot analysis showed that MNK expression was greater in lactating tissue than in nonlactating tissue. By confocal immunofluorescence, the MNK was detected in luminal epithelial cells of the alveoli and ducts but not in myoepithelial cells. In the nonlactating breast epithelial cells, the MNK had a predominantly perinuclear distribution. In lactating breast tissue, the distribution of the MNK was markedly altered. Lactating epithelial cells showed a granular, diffuse pattern, which extended beyond the perinuclear region of the cell. This pattern was similar to that observed in a previous study in which cultured CHO cells were exposed to high copper concentrations. Our results suggest that relocalization of the MNK is a physiological process, which may be mediated by copper levels in the breast or by hormones and other events taking place during lactation. A vesicular pathway for copper from the Golgi into milk, similar to that of calcium, is proposed.
Publisher: Oxford University Press (OUP)
Date: 16-03-2019
DOI: 10.1093/MNRAS/STZ799
Publisher: S. Karger AG
Date: 2007
DOI: 10.1159/000110718
Abstract: The copper transporting ATPases, Menkes (ATP7A MNK) and Wilson (ATP7B WND) are essential for normal copper transport in the human body. The placenta is the key organ in copper supply to the fetus during pregnancy and it is one of the few organs in the body to express both of the ATPases. The placenta therefore provides a unique opportunity to elucidate the specific roles of these transporters within the one cell type. Using polarized placental Jeg-3 cells, siRNA technology and radio-labelled 64Cu transport assays, MNK and WND were shown to have distinct roles in the vectorial transport of copper. MNK transported copper from the cell via the basolateral membrane and in contrast, WND transported copper from the apical membrane. Inactivation of MNK resulted in decreased activity of two important cuproenzymes, lysyl oxidase and Cu/Zn-superoxide dismutase. Overall, these results provide definitive evidence for distinct roles of MNK and WND in the human placenta, and are consistent with a role for MNK in the transport of copper into the fetal circulation, and through delivery of copper to placental cuproenzymes, whilst WND contributes to the maintenance of placental copper homeostasis by transporting copper to the maternal circulation.
Publisher: Springer Science and Business Media LLC
Date: 02-02-2013
No related grants have been discovered for Agnes Michalczyk.