There is experimental evidence that dietary fish oil, which contains the n-3 fatty acid family, i... more There is experimental evidence that dietary fish oil, which contains the n-3 fatty acid family, i.e., EPA and DHA, protects against colon tumor development, in part by increasing apoptosis. Since mitochondria can act as central executioners of apoptosis, we hypothesized that EPA and DHA incorporation into colonocyte mitochondrial membranes, owing to their high degree of unsaturation, would enhance susceptibility to damage by reactive oxygen species (ROS) generated via oxidative phosphorylation. This, in turn, would compromise mitochondrial function, thereby initiating apoptosis. To test this hypothesis, colonic crypts were isolated from rats fed either fish oil, purified n-3 fatty acid ethyl esters, or corn oil (control). Dietary lipid source had no effect on colonic mitochondrial phospholipid class mole percentages, although incorporation of EPA and DHA was associated with a reduction in n-6 fatty acids known to enhance colon tumor development, i.e., linoleic acid LNA) and its metabolic product, arachidonic acid (ARA). Select compositional changes in major phospholipid pools were correlated to alterations in mitochondrial function as assessed by confocal microscopy. The mol% sum of LNA plus ARA in cardiolipin was inversely correlated with ROS (P = 0.024). Ethanolamine glycerophospholipid ARA (P = 0.046) and choline glycerophospholipid LNA (P = 0.033) levels were positively correlated to mitochondrial membrane potential. In contrast, ethanolamine glycerophospholipid EPA (P = 0.042) and DHA (P = 0.024) levels were negatively correlated to mitochondrial membrane potential. Additionally, EPA and DHA levels in choline glycerophospholipids (P = 0.026) were positively correlated with caspase 3 activity. These data provide evidence in vivo indicating that dietary EPA and DHA induce compositional changes in colonic mitochondrial membrane phospholipids that facilitate apoptosis.
We previously demonstrated that a modified secreted form of fibroblast growth factor 1 (FGF-1), a... more We previously demonstrated that a modified secreted form of fibroblast growth factor 1 (FGF-1), a prototypic member of the FGF family, has the ability to stimulate angiogenesis in an in vivo model of angiogenesis, the so-called chick chorioallantoic membrane assay or CAM. We recently defined the importance of the phosphatidylinositol 3-kinase/AKT pathway in FGF-1-mediated angiogenesis in this model using specific pharmacological inhibitors. In our continuing efforts to define the molecular signaling pathway regulating FGF-1-induced angiogenesis in vivo, we utilized a transcription factor activity assay and identified transcription factor Ets-1 as a critical effector of FGF-1-induced angiogenesis. Both activity and mRNA expression levels of the Ets-1 molecule were increased in response to FGF-1 overexpression in CAMs, as documented by electrophoretic mobility shift assay (gel shift) and reverse transcription real-time PCR techniques, respectively. Furthermore, the delivery of Ets-1 a...
A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 a... more A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 amino acid residue protein (65.2 kDa) predicted as a G protein-coupled receptor and orthologue of the drosokinin receptor from Drosophila melanogaster and highly similar to the tick Boophilus microplus myokinin receptor (AF228521). Based on the similarity to this Aedes sequence, we also propose a correction for the Anopheles gambiae protein sequence EAA05450. When expressed in CHO-K1 cells, the Aedes receptor behaved as a multiligand receptor and functionally responded to concentrations > or = 1 nM of Aedae kinins 1-3, respectively, as determined by a calcium bioluminescence plate assay and single cell intracellular calcium measurements by confocal fluorescence cytometry. Estimates of EC50 values by the plate assay were 16.04 nM for Aedae-K-3, 26.6 nM for Aedae-K-2 and 48.8 nM for Aedae-K-1 and were statistically significantly different. These results suggest that the observed differences in physiological responses to the three Aedes kinins in the Aedes isolated Malpighian tubule reported elsewhere could now be explained by differences in intracellular signalling events triggered by the different peptides on the same receptor and not necessarily due to the existence of various receptors for the three Aedes kinins.
3-Methylcholanthrene (3MC) is an aryl hydrocarbon receptor (AhR) agonist, and it has been reporte... more 3-Methylcholanthrene (3MC) is an aryl hydrocarbon receptor (AhR) agonist, and it has been reported that 3MC induces estrogenic activity through AhR-estrogen receptor α (ERα) interactions. In this study, we used 3MC and 3,3′,4,4′,5-pentachlorobiphenyl (PCB) as prototypical AhR ligands, and both compounds activated estrogen-responsive reporter genes/gene products (cathepsin D) in MCF-7 breast cancer cells. The estrogenic responses induced by these AhR ligands were inhibited by the antiestrogen ICI 182780 and by the transfection of a small inhibitory RNA for ERα but were not affected by the small inhibitory RNA for AhR. These results suggest that 3MC and PCB directly activate ERα, and this was confirmed in a competitive ERα binding assay and in a fluorescence resonance energy transfer experiment in which PCB and 3MC induced CFP-ERα/YFP-ERα interactions. In a chromatin immunoprecipitation assay, PCB and 3MC enhanced ERα (but not AhR) association with the estrogen-responsive region of th...
Ras signaling originates from transient nanoscale compartmentalized regions of the plasma membran... more Ras signaling originates from transient nanoscale compartmentalized regions of the plasma membrane composed of specific proteins and lipids. The highly specific lipid composition of these nanodomains, termed nanoclusters, facilitates effector recruitment and therefore influences signal transduction. This suggests that Ras nanocluster proteolipid composition could represent a novel target for future chemoprevention interventions. There is evidence that consumption of fish oil containing long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) such as eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) may reduce colon cancer risk in humans, yet the mechanism underlying this effect is unknown. Here, we demonstrate that dietary n-3 PUFA reduce the lateral segregation of cholesterol-dependent and -independent nanoclusters, suppressing phosphatidic acid-dependent oncogenic KRas effector interactions, via their physical incorporation into plasma membrane phospholipids. Thi...
There is experimental evidence that dietary fish oil, which contains the n-3 fatty acid family, i... more There is experimental evidence that dietary fish oil, which contains the n-3 fatty acid family, i.e., EPA and DHA, protects against colon tumor development, in part by increasing apoptosis. Since mitochondria can act as central executioners of apoptosis, we hypothesized that EPA and DHA incorporation into colonocyte mitochondrial membranes, owing to their high degree of unsaturation, would enhance susceptibility to damage by reactive oxygen species (ROS) generated via oxidative phosphorylation. This, in turn, would compromise mitochondrial function, thereby initiating apoptosis. To test this hypothesis, colonic crypts were isolated from rats fed either fish oil, purified n-3 fatty acid ethyl esters, or corn oil (control). Dietary lipid source had no effect on colonic mitochondrial phospholipid class mole percentages, although incorporation of EPA and DHA was associated with a reduction in n-6 fatty acids known to enhance colon tumor development, i.e., linoleic acid LNA) and its metabolic product, arachidonic acid (ARA). Select compositional changes in major phospholipid pools were correlated to alterations in mitochondrial function as assessed by confocal microscopy. The mol% sum of LNA plus ARA in cardiolipin was inversely correlated with ROS (P = 0.024). Ethanolamine glycerophospholipid ARA (P = 0.046) and choline glycerophospholipid LNA (P = 0.033) levels were positively correlated to mitochondrial membrane potential. In contrast, ethanolamine glycerophospholipid EPA (P = 0.042) and DHA (P = 0.024) levels were negatively correlated to mitochondrial membrane potential. Additionally, EPA and DHA levels in choline glycerophospholipids (P = 0.026) were positively correlated with caspase 3 activity. These data provide evidence in vivo indicating that dietary EPA and DHA induce compositional changes in colonic mitochondrial membrane phospholipids that facilitate apoptosis.
We previously demonstrated that a modified secreted form of fibroblast growth factor 1 (FGF-1), a... more We previously demonstrated that a modified secreted form of fibroblast growth factor 1 (FGF-1), a prototypic member of the FGF family, has the ability to stimulate angiogenesis in an in vivo model of angiogenesis, the so-called chick chorioallantoic membrane assay or CAM. We recently defined the importance of the phosphatidylinositol 3-kinase/AKT pathway in FGF-1-mediated angiogenesis in this model using specific pharmacological inhibitors. In our continuing efforts to define the molecular signaling pathway regulating FGF-1-induced angiogenesis in vivo, we utilized a transcription factor activity assay and identified transcription factor Ets-1 as a critical effector of FGF-1-induced angiogenesis. Both activity and mRNA expression levels of the Ets-1 molecule were increased in response to FGF-1 overexpression in CAMs, as documented by electrophoretic mobility shift assay (gel shift) and reverse transcription real-time PCR techniques, respectively. Furthermore, the delivery of Ets-1 a...
A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 a... more A cDNA cloned from Aedes aegypti (L.) (Aedae) female Malpighian tubule (AY596453) encodes a 584 amino acid residue protein (65.2 kDa) predicted as a G protein-coupled receptor and orthologue of the drosokinin receptor from Drosophila melanogaster and highly similar to the tick Boophilus microplus myokinin receptor (AF228521). Based on the similarity to this Aedes sequence, we also propose a correction for the Anopheles gambiae protein sequence EAA05450. When expressed in CHO-K1 cells, the Aedes receptor behaved as a multiligand receptor and functionally responded to concentrations > or = 1 nM of Aedae kinins 1-3, respectively, as determined by a calcium bioluminescence plate assay and single cell intracellular calcium measurements by confocal fluorescence cytometry. Estimates of EC50 values by the plate assay were 16.04 nM for Aedae-K-3, 26.6 nM for Aedae-K-2 and 48.8 nM for Aedae-K-1 and were statistically significantly different. These results suggest that the observed differences in physiological responses to the three Aedes kinins in the Aedes isolated Malpighian tubule reported elsewhere could now be explained by differences in intracellular signalling events triggered by the different peptides on the same receptor and not necessarily due to the existence of various receptors for the three Aedes kinins.
3-Methylcholanthrene (3MC) is an aryl hydrocarbon receptor (AhR) agonist, and it has been reporte... more 3-Methylcholanthrene (3MC) is an aryl hydrocarbon receptor (AhR) agonist, and it has been reported that 3MC induces estrogenic activity through AhR-estrogen receptor α (ERα) interactions. In this study, we used 3MC and 3,3′,4,4′,5-pentachlorobiphenyl (PCB) as prototypical AhR ligands, and both compounds activated estrogen-responsive reporter genes/gene products (cathepsin D) in MCF-7 breast cancer cells. The estrogenic responses induced by these AhR ligands were inhibited by the antiestrogen ICI 182780 and by the transfection of a small inhibitory RNA for ERα but were not affected by the small inhibitory RNA for AhR. These results suggest that 3MC and PCB directly activate ERα, and this was confirmed in a competitive ERα binding assay and in a fluorescence resonance energy transfer experiment in which PCB and 3MC induced CFP-ERα/YFP-ERα interactions. In a chromatin immunoprecipitation assay, PCB and 3MC enhanced ERα (but not AhR) association with the estrogen-responsive region of th...
Ras signaling originates from transient nanoscale compartmentalized regions of the plasma membran... more Ras signaling originates from transient nanoscale compartmentalized regions of the plasma membrane composed of specific proteins and lipids. The highly specific lipid composition of these nanodomains, termed nanoclusters, facilitates effector recruitment and therefore influences signal transduction. This suggests that Ras nanocluster proteolipid composition could represent a novel target for future chemoprevention interventions. There is evidence that consumption of fish oil containing long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) such as eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) may reduce colon cancer risk in humans, yet the mechanism underlying this effect is unknown. Here, we demonstrate that dietary n-3 PUFA reduce the lateral segregation of cholesterol-dependent and -independent nanoclusters, suppressing phosphatidic acid-dependent oncogenic KRas effector interactions, via their physical incorporation into plasma membrane phospholipids. Thi...
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Papers by Rola Barhoumi