Cholesterol and cholesterol plus DHA diet-induced gene expression and fatty acid changes in mouse eye and brain

ω-3 and ω-6 long-chain PUFAs and their enzymatic metabolites in neovascular eye diseases

Neovascular eye diseases, including retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration, threaten the visual health of children and adults. Current treatment options, including anti-vascular endothelial growth factor therapy and laser retinal photocoagulation, have limitations and are associated with adverse effects; therefore, the identification of additional therapies is highly desirable. Both clinical and experimental studies show that dietary ω-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFAs) reduce retinal and choroidal angiogenesis. The ω-3 LC-PUFA metabolites from 2 groups of enzymes, cyclooxygenases and lipoxygenases, inhibit [and the ω-6 (n-6) LC-PUFA metabolites promote] inflammation and angiogenesis. However, both of the ω-3 and the ω-6 lipid products of cytochrome P450 oxidase 2C promote neovascularization in both the retina and choroid, which suggests that inhibition of this pathway might be beneficial. This review summarizes our current understanding of the roles of ω-3 and ω-6 LC-PUFAs and their enzymatic metabolites in neovascular eye diseases.

Inflammation and Cancer: Extra- and Intracellular Determinants of Tumor-Associated Macrophages as Tumor Promoters

One of the hallmarks of cancer-related inflammation is the recruitment of monocyte-macrophage lineage cells to the tumor microenvironment. These tumor infiltrating myeloid cells are educated by the tumor milieu, rich in cancer cells and stroma components, to exert functions such as promotion of tumor growth, immunosuppression, angiogenesis, and cancer cell dissemination. Our review highlights the ontogenetic diversity of tumor-associated macrophages (TAMs) and describes their main phenotypic markers. We cover fundamental molecular players in the tumor microenvironment including extra- (CCL2, CSF-1, CXCL12, IL-4, IL-13, semaphorins, WNT5A, and WNT7B) and intracellular signals. We discuss how these factors converge on intracellular determinants (STAT3, STAT6, STAT1, NF-κB, RORC1, and HIF-1α) of cell functions and drive the recruitment and polarization of TAMs. Since microRNAs (miRNAs) modulate macrophage polarization key miRNAs (miR-146a, miR-155, miR-125a, miR-511, and miR-223) are also discussed in the context of the inflammatory myeloid tumor compartment. Accumulating evidence suggests that high TAM infiltration correlates with disease progression and overall poor survival of cancer patients. Identification of molecular targets to develop new therapeutic interventions targeting these harmful tumor infiltrating myeloid cells is emerging nowadays.

Tissue-specific Gene Expression in Rat Hearts and Aortas in a Model of Vascular Nitrate Tolerance

Nitroglycerin exerts a direct myocardial anti-ischemic effect even in the state of vascular nitrate tolerance. To examine the potentially diverse molecular responses in vascular and cardiac tissues, we investigated the gene expression profile of the heart and the aorta by DNA microarray in male Wistar rats that were previously made tolerant to the vascular effects of nitroglycerin. The blood pressure-lowering effect of nitroglycerin (1-100 μg/kg) was markedly attenuated in rats pretreated for 3 days with 3 × 100 mg/kg nitroglycerin. Nitric oxide content was significantly elevated in the heart but not in the aorta of nitrate-tolerant animals, which indicated tissue-specific differences in nitroglycerin bioconversion. Of 7742 genes analyzed by DNA microarray, we found that although the expression of 25 genes changed significantly in the heart (increased: Tas2r119, Map6, Cd59, Kcnh2, Kcnh3, Senp6, Mcpt1, Tshb, Haus1, Vipr1, Lrn3, Lifr; decreased: Ihh, Fgfr1, Cryge, Krt9, Agrn, C4bpb, Fcer1a, Csf3, Hsd17b11, Hsd11b2, Ctnnbl1, Prpg1, Hsf1), only 14 genes were altered in the aorta (increased: Tas2r119, Ihh, Rrad, Npm1, Snai1; decreased: Tubb2b, Usp15, Sema6c, Wfdc2, Rps21, Ramp2, Galr1, Atxn1, Lhx1) in vascular nitrate tolerance. Quantitative reverse transcription polymerase chain reaction analysis of genes related to oxidative/nitrative/nitrosative stress also showed differential expression pattern in the heart and aorta. This is the first pharmacogenomic analysis showing that nitroglycerin treatment leading to vascular nitrate tolerance differentially impacts gene expression in vascular and cardiac tissues, which indicates different tissue-specific downstream signaling pathways.

Transcriptomic analysis of the effects of a fish oil enriched diet on murine brains

The health benefits of fish oil enriched with high omega-3 polyunsaturated fatty acids (n-3 PUFA) are widely documented. Fish oil as dietary supplements, however, show moderate clinical efficacy, highlighting an immediate scope of systematic in vitro feedback. Our transcriptomic study was designed to investigate the genomic shift of murine brains fed on fish oil enriched diets. A customized fish oil enriched diet (FD) and standard lab diet (SD) were separately administered to two randomly chosen populations of C57BL/6J mice from their weaning age until late adolescence. Statistical analysis mined 1,142 genes of interest (GOI) differentially altered in the hemibrains collected from the FD- and SD-fed mice at the age of five months. The majority of identified GOI (∼40%) encodes proteins located in the plasma membrane, suggesting that fish oil primarily facilitated the membrane-oriented biofunctions. FD potentially augmented the nervous system's development and functions by selectively stimulating the Src-mediated calcium-induced growth cascade and the downstream PI3K-AKT-PKC pathways. FD reduced the amyloidal burden, attenuated oxidative stress, and assisted in somatostatin activation—the signatures of attenuation of Alzheimer's disease, Parkinson's disease, and affective disorder. FD induced elevation of FKBP5 and suppression of BDNF, which are often linked with the improvement of anxiety disorder, depression, and post-traumatic stress disorder. Hence we anticipate efficacy of FD in treating illnesses such as depression that are typically triggered by the hypoactivities of dopaminergic, adrenergic, cholinergic, and GABAergic networks. Contrastingly, FD's efficacy could be compromised in treating illnesses such as bipolar disorder and schizophrenia, which are triggered by hyperactivities of the same set of neuromodulators. A more comprehensive investigation is recommended to elucidate the implications of fish oil on disease pathomechanisms, and the result-driven repositioning of fish oil utilization may revitalize its therapeutic efficacy.

Tissue-specific transcriptional modulation of fatty acid-binding protein genes, fabp2, fabp3 and fabp6, by fatty acids and the peroxisome proliferator, clofibrate, in zebrafish (Danio rerio)

All fabp genes, except fabp2, fabp3 and fabp6, exist as duplicates in the zebrafish genome owing to a whole genome duplication event ~230-400 million years ago. Transcription of some duplicated fabp genes is modulated by fatty acids (FAs) and/or clofibrate, a peroxisome proliferator-activated receptor (PPAR) agonist. We had also shown previously that the steady-state level of acyl-CoA oxidase 1 (acox1) mRNA, a marker of PPARα activation, was elevated in liver, intestine, heart and muscle of fish fed clofibrate demonstrating that zebrafish, unlike some fishes, is responsive to this drug. acox1 transcripts were not induced in the brain of fish fed clofibrate, which suggests this drug may not cross the blood brain barrier. Here, we investigated the effect of dietary FAs and clofibrate on the transcription of single copy fabp genes, fabp2, fabp3 and fabp6, in five tissues of inbred zebrafish. The steady-state level of fabp2 transcripts increased in intestine, while fabp3 mRNA increased in liver of fish fed diets differing in FA content. In fish fed clofibrate, fabp3 mRNA in intestine, and fabp6 mRNA in intestine and heart, were elevated. Based on these findings, modulation of fabp2, fabp3 and fabp6 transcription by FAs and/or clofibrate in zebrafish implicates control of these genes by PPAR interaction with peroxisome proliferator response elements (PPRE) most likely in fabp promoters. Moreover, transcriptional induction of these fabp genes by dietary FAs and/or clofibrate is over-ridden by a tissue-specific mechanism(s), e.g., transcriptional activator or repressor proteins.

Omega-3 fatty acids in neurodegenerative diseases: focus on mitochondria

Mitochondrial dysfunction represents a common early pathological event in brain aging and in neurodegenerative diseases, e.g., in Alzheimer's (AD), Parkinson's (PD), and Huntington's disease (HD), as well as in ischemic stroke. In vivo and ex vivo experiments using animal models of aging and AD, PD, and HD mainly showed improvement of mitochondrial function after treatment with polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA). Thereby, PUFA are particular beneficial in animals treated with mitochondria targeting toxins. However, DHA showed adverse effects in a transgenic PD mouse model and it is not clear if a diet high or low in PUFA might provide neuroprotective effects in PD. Post-treatment with PUFA revealed conflicting results in ischemic animal models, but intravenous administered DHA provided neuroprotective efficacy after acute occlusion of the middle cerebral artery. In summary, the majority of preclinical data indicate beneficial effects of n-3 PUFA in neurodegenerative diseases, whereas most controlled clinical trials did not meet the expectations. Because of the high half-life of DHA in the human brain clinical studies may have to be initiated much earlier and have to last much longer to be more efficacious.

Effect of essential fatty acids on glucose-induced cytotoxicity to retinal vascular endothelial cells

Background

Diabetic retinopathy is a major complication of dysregulated hyperglycemia. Retinal vascular endothelial cell dysfunction is an early event in the pathogenesis of diabetic retinopathy. Studies showed that hyperglycemia-induced excess proliferation of retinal vascular endothelial cells can be abrogated by docosahexaenoic acid (DHA, 22:6 ω-3) and eicosapentaenoic acid (EPA, 20:5 ω-3). The influence of dietary omega-3 PUFA on brain zinc metabolism has been previously implied. Zn²⁺ is essential for the activity of Δ⁶ desaturase as a co-factor that, in turn, converts essential fatty acids to their respective long chain metabolites. Whether essential fatty acids (EFAs) α-linolenic acid and linoleic acid have similar beneficial effect remains poorly understood.

Methods

RF/6A cells were treated with different concentrations of high glucose, α-linolenic acid and linoleic acid and Zn²⁺. The alterations in mitochondrial succinate dehydrogenase enzyme activity, cell membrane fluidity, reactive oxygen species generation, SOD enzyme and vascular endothelial growth factor (VEGF) secretion were evaluated.

Results

Studies showed that hyperglycemia-induced excess proliferation of retinal vascular endothelial cells can be abrogated by both linoleic acid (LA) and α-linolenic acid (ALA), while the saturated fatty acid, palmitic acid was ineffective. A dose–response study with ALA showed that the activity of the mitochondrial succinate dehydrogenase enzyme was suppressed at all concentrations of glucose tested to a significant degree. High glucose enhanced fluorescence polarization and microviscocity reverted to normal by treatment with Zn²⁺ and ALA. ALA was more potent that Zn²⁺. Increased level of high glucose caused slightly increased ROS generation that correlated with corresponding decrease in SOD activity. ALA suppressed ROS generation to a significant degree in a dose dependent fashion and raised SOD activity significantly. ALA suppressed high-glucose-induced VEGF secretion by RF/6A cells.

Conclusions

These results suggest that EFAs such as ALA and LA may have beneficial action in the prevention of high glucose-induced cellular damage.

The involvement of gap junctions in the delayed phase of the protection induced by cardiac pacing in dogs

The present study has examined the role of GJ (gap junctions) in the delayed anti-arrhythmic effect of cardiac pacing, with particular reference to the time-course changes in Cx43 (connexin43) expression both after pacing (4×5 min, at a rate of 240 beats/min) and 24 h later, when the dogs were subjected to a 25 min occlusion and reperfusion of the LAD (left anterior descending coronary artery). Compared with the SP (sham-paced) controls (n=20), in dogs paced 24 h previously (n=16) there were reductions in arrhythmia severity [e.g. number of VPB (ventricular premature beats) during occlusion 294±78 compared with 63±25; survival from the combined ischaemia/reperfusion insult 20% compared with 78%], and in other ischaemic changes [epicardial ST-segment, TAT (total activation time) and tissue impedance]. Pacing also prevented the ischaemia-induced structural impairment of the intercalated discs, and preserved GJ permeability and Cx43 phosphorylation, without modifying Cx43 protein content. Following cardiac pacing the membrane and total Cx43 protein contents were unchanged up to 6 h, but were significantly reduced 12 h later (preceded by a down-regulation of Cx43 mRNA at 6 h), and returned to normal by 24 h. Interestingly, dogs that were subjected to ischaemia 12 h after cardiac pacing showed increased arrhythmia generation. We conclude that cardiac pacing results in time-dependent changes in Cx43 expression, which may alter GJ function and influence arrhythmia generation during a subsequent ischaemia/reperfusion insult. This effect is manifested in protection 24 h after pacing, but of potential clinical interest is the finding that there is a time interval after pacing during which an ischaemic event may generate severe ventricular arrhythmias.

Purification of high-quality micro RNA from the heart tissue

Micro RNAs (miRNA) are an abundant class of small RNAs that regulate the stability and translation of cognate mRNAs. MiRNAs are potential diagnostic markers, moreover, they play an essential role in the development of various heart disesases. In case of limited tissue material, such as, e.g. human biopsies, purification of miRNAs with sufficient yield is critical. Reproducible expression analysis of miRNAs is highly dependent on the quality of the RNA, which is often difficult to achieve from fibrous tissue such as the heart. Several companies developed general purification kits for miRNAs, however, none of them are specialized to fibrotic tissues. Here we describe an optimized miRNA purification protocol that results in high miRNA yield as compared to other methods including trizol-based and column-based protocols. By using our improved protocol, miRNA obtained from heart tissue gave more reproducible results in QRT-PCR analysis and obtained more significant calls (172 vs. 118) during DNA microarray analysis when compared to the commercially available kit. In addition to the heart tissue, the present protocol can be applied to other fibrotic tissues, such as lung or skeletal muscle to isolate high-purity miRNA.

Hypothalamic gene expression in ω-3 PUFA-deficient male rats before, and following, development of hypertension

Dietary deficiency of ω-3 fatty acids (ω-3 DEF) produces hypertension in later life. This study examined the effect of ω-3 DEF on blood pressure and hypothalamic gene expression in young rats, before the development of hypertension, and in older rats following the onset of hypertension. Animals were fed experimental diets that were deficient in ω-3 fatty acids, sufficient in short-chain ω-3 fatty acids or sufficient in short- and long-chain ω-3 fatty acids, from the prenatal period until 10 or 36 weeks-of-age. There was no difference in blood pressure between groups at 10 weeks-of-age; however, at 36 weeks-of-age ω-3 DEF animals were hypertensive in relation to sufficient groups. At 10 weeks, expression of angiotensin-II(1A) receptors and dopamine D(3) receptors were significantly increased in the hypothalamic tissue of ω-3 DEF animals. In contrast, at 36 weeks, α(2a) and β(1) adrenergic receptor expression was significantly reduced in the ω-3 DEF group. Brain docosahexaenoic acid was significantly lower in ω-3 DEF group compared with sufficient groups. This study demonstrates that dietary ω-3 DEF causes changes both in the expression of key genes involved in central blood pressure regulation and in blood pressure. The data may indicate that hypertension resulting from ω-3 DEF is mediated by the central adrenergic system.

Identification of novel mammalian phospholipids containing threonine, aspartate, and glutamate as the base moiety

In this study, we showed the occurrence of phosphatidyl-L-threonine (PThr), phosphatidyl-L-aspartate (PAsp), and phosphatidyl-L-glutamate (PGlu) in rat brain. Analyses using an HPLC-ESI-MS and an amino acid analyzer showed the presence of L-threonine, L-aspartate, and L-glutamate in the acid-hydrolysates of phospholipids from porcine cerebrum, rat cerebrum, and rat liver. Results of ESI-MS/MS analyses with neutral loss scanning and product ion scanning suggest the presence of PThr-(18:0, 18:1), PThr-(18:0, 22:6), PAsp-(18:0, 18:1), PAsp-(18:0, 22:6), PGlu-(18:0, 18:1), and PGlu-(18:0, 22:6) in rat brain. This is the first study to identify 2 novel phospholipids, PAsp and PGlu, with a carboxylate-phosphate anhydride bond, in living organisms.

MicroRNA profile of polyunsaturated fatty acid treated glioma cells reveal apoptosis-specific expression changes

BACKGROUND

Polyunsaturated fatty acids (PUFAs) such as γ-linolenic acid (GLA), arachidonic acid (AA) and docosahexaenoic acid (DHA) have cytotoxic action on glioma cells.

RESULTS

We evaluated the cytotoxic action of GLA, AA and DHA on glioma cells with specific reference to the expression of miRNAs. Relative expression of miRNAs were assessed by using high throughput nanocapillary real-time PCR. Most of the miRNA target genes that showed altered expression could be classified as apoptotic genes and were up-regulated by PUFA or temozolomide treatment, while similar treatments resulted in repression of the corresponding mRNAs, such as cox2, irs1, irs2, ccnd1, itgb3, bcl2, sirt1, tp53inp1 and k-ras.

CONCLUSIONS

Our results highlight involvement of miRNAs in the induction of apoptosis in glioma cells by fatty acids and temozolomide.

Functional changes in transcriptomes of the prefrontal cortex and hippocampus in a mouse model of anxiety

Anxiety is a multi-etiology disorder influenced by both genetic background and environment. To study the impact of a genetic predisposition, we developed a novel mouse model of anxiety using a combination of crossbreeding and behavioral selection. Comparison of the transcriptomes from the prefrontal cortex and hippocampus of anxious and control mice revealed that the numbers of significantly up- and down-regulated genes were modest, comprising approximately 2% of the tested genes. Functional analysis of the significantly altered gene sets showed that functional groups such as nervous system development, behavior, glial cell differentiation and synaptic transmission were significantly enriched among the up-regulated genes, whereas functional groups such as potassium ion transport, Wnt signaling and neuropeptidergic signaling were significantly enriched among the down-regulated genes. Many of the identified genes and functional groups have been previously linked to the molecular biology of anxiety, while several others, such as transthyretin, vasoactive intestinal polypeptide and various potassium ion channels, are novel or not as well described in this context. Supporting the gene expression data, we also found increased excitability in the hippocampi of anxious mice, which can be a phenotypic result of decreased potassium channel density. Our transcriptome screen showed that the initiation and/or effect of anxiety involve multiple pathways and cellular processes. The identified novel genes and pathways could be involved in the molecular pathogenesis of anxiety and provide potential targets for further drug development.

Changes in gene expression following cardiac pacing-induced delayed cardioprotection in the canine heart

The aim of the present study was to identify gene expression changes in the rapid cardiac pacing-induced delayed antiarrhythmic protection in the canine, using cDNA microarrays and quantitative real-time PCR (QRT -PCR) techniques. In all dogs under light pentobarbitone anaesthesia, a pacing electrode was introduced into the right ventricle, and then the animals were divided into three groups: (1) sham-operated and sham-paced group (SP, n = 3) (2) ischaemic control group (IC; n = 3); these were without cardiac pacing and subjected only to a 25 min occlusion of the left anterior descending coronary artery (LAD), and (3) paced group (PC, n = 3); these animals were paced at a rate of 220-240 beats min-1 24 h prior to ischaemia. With cDNA chip 23 genes were found with altered expression in response to rapid cardiac pacing and 10 genes in the IC group when compared to SP dogs. These genes encode transcription factors (MEF2); members of signaling pathways (TGFβ2, PDE4D9), hormone related proteins (e.g. vasopressin V1 and V2 receptors). RT-QPCR was used either to confirm the results of the microarray analysis and also to study 46 genes which are already known to have a role in the late phase of PC. By this method 17 genes were up-regulated and 6 genes down-regulated in the IC group; their expression ratios changed either to the opposite or showed no alteration after cardiac pacing. This study would add some new information about those transcriptional changes that are involved in the delayed phase of cardiac protection.

Neuroprotective effects of active ingredients isolated from Pegasus laternarius on cultured cerebral neurons

Seamoth (Pegasus laternarius Cuvier) is extensively used to treat various diseases on the coastland of Guangdong Province in China, such as scrofula, cough, and diarrhea. The total extract of Pegasus laternarius (EP) was subjected to column chromatography to acquire three different constituents (EPC1, EPC2, and EPC3). Cerebral neuron injury was induced by glutamate, H₂O₂, and serum deprivation. After treating with or without different extracts, cell viability was assessed with the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and cell apoptosis was analyzed with Hoechst 33258 staining and agarose gel electrophoresis. We also determined the levels of lactate dehydrogenase (LDH), maleic dialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). The results showed that both EP and EPC2 promoted the outgrowth of cultural neurons, increased antioxidant enzyme activity, and protected neurons from neuronal injury or apoptosis induced by glutamate, H₂O₂, and serum deprivation. EPC1 and EPC3 had little or no effect on neurons. These results suggest that the active ingredients obtained from Pegasus laternarius have potential neuroprotective effects on injured neurons by promoting the outgrowth of cultured neurons, increasing the activity of intracellular antioxidants, and exerting antiapoptotic effects. This neuroprotection may be attributable to specific active ingredients, such as taurine, novel ceramide, and cholesterol.

PPARalpha: an emerging therapeutic target in diabetic microvascular damage

The global pandemic of diabetes mellitus portends an alarming rise in the prevalence of microvascular complications, despite advanced therapies for hyperglycemia, hypertension and dyslipidemia. Peroxisome proliferator-activated receptor alpha (PPARalpha) is expressed in organs affected by diabetic microvascular disease (retina, kidney and nerves), and its expression is regulated specifically in these tissues. Experimental evidence suggests that PPARalpha activation attenuates or inhibits several mediators of vascular damage, including lipotoxicity, inflammation, reactive oxygen species generation, endothelial dysfunction, angiogenesis and thrombosis, and thus might influence intracellular signaling pathways that lead to microvascular complications. PPARalpha has emerged as a novel target to prevent microvascular disease, via both its lipid-related and lipid-unrelated actions. Despite strong experimental evidence of the potential benefits of PPARalpha agonists in the prevention of vascular damage, the evidence from clinical studies in patients with diabetes mellitus remains limited. Promising findings from the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study on microvascular outcomes are countered by elevations in participants' homocysteine and creatinine levels that might potentially attenuate the benefits of PPARalpha activation. This Review focuses on the role of PPARalpha activation in diabetic microvascular disease and highlights the available experimental and clinical evidence from studies of PPARalpha agonists.

Polyunsaturated fatty acids synergize with lipid droplet binding thalidomide analogs to induce oxidative stress in cancer cells

Background

Cytoplasmic lipid-droplets are common inclusions of eukaryotic cells. Lipid-droplet binding thalidomide analogs (2,6-dialkylphenyl-4/5-amino-substituted-5,6,7-trifluorophthalimides) with potent anticancer activities were synthesized.

Results

Cytotoxicity was detected in different cell lines including melanoma, leukemia, hepatocellular carcinoma, glioblastoma at micromolar concentrations. The synthesized analogs are non-toxic to adult animals up to 1 g/kg but are teratogenic to zebrafish embryos at micromolar concentrations with defects in the developing muscle. Treatment of tumor cells resulted in calcium release from the endoplasmic reticulum (ER), induction of reactive oxygen species (ROS), ER stress and cell death. Antioxidants could partially, while an intracellular calcium chelator almost completely diminish ROS production. Exogenous docosahexaenoic acid or eicosapentaenoic acid induced calcium release and ROS generation, and synergized with the analogs in vitro, while oleic acid had no such an effect. Gene expression analysis confirmed the induction of ER stress-mediated apoptosis pathway components, such as GADD153, ATF3, Luman/CREB3 and the ER-associated degradation-related HERPUD1 genes. Tumor suppressors, P53, LATS2 and ING3 were also up-regulated in various cell lines after drug treatment. Amino-phthalimides down-regulated the expression of CCL2, which is implicated in tumor metastasis and angiogenesis.

Conclusions

Because of the anticancer, anti-angiogenic action and the wide range of applicability of the immunomodulatory drugs, including thalidomide analogs, lipid droplet-binding members of this family could represent a new class of agents by affecting ER-membrane integrity and perturbations of ER homeostasis.

Differential transcriptional modulation of duplicated fatty acid-binding protein genes by dietary fatty acids in zebrafish (Danio rerio): evidence for subfunctionalization or neofunctionalization of duplicated genes

Background

In the Duplication-Degeneration-Complementation (DDC) model, subfunctionalization and neofunctionalization have been proposed as important processes driving the retention of duplicated genes in the genome. These processes are thought to occur by gain or loss of regulatory elements in the promoters of duplicated genes. We tested the DDC model by determining the transcriptional induction of fatty acid-binding proteins (Fabps) genes by dietary fatty acids (FAs) in zebrafish. We chose zebrafish for this study for two reasons: extensive bioinformatics resources are available for zebrafish at zfin.org and zebrafish contains many duplicated genes owing to a whole genome duplication event that occurred early in the ray-finned fish lineage approximately 230-400 million years ago. Adult zebrafish were fed diets containing either fish oil (12% lipid, rich in highly unsaturated fatty acid), sunflower oil (12% lipid, rich in linoleic acid), linseed oil (12% lipid, rich in linolenic acid), or low fat (4% lipid, low fat diet) for 10 weeks. FA profiles and the steady-state levels of fabp mRNA and heterogeneous nuclear RNA in intestine, liver, muscle and brain of zebrafish were determined.

Result

FA profiles assayed by gas chromatography differed in the intestine, brain, muscle and liver depending on diet. The steady-state level of mRNA for three sets of duplicated genes, fabp1a/fabp1b.1/fabp1b.2, fabp7a/fabp7b, and fabp11a/fabp11b, was determined by reverse transcription, quantitative polymerase chain reaction (RT-qPCR). In brain, the steady-state level of fabp7b mRNAs was induced in fish fed the linoleic acid-rich diet; in intestine, the transcript level of fabp1b.1 and fabp7b were elevated in fish fed the linolenic acid-rich diet; in liver, the level of fabp7a mRNAs was elevated in fish fed the low fat diet; and in muscle, the level of fabp7a and fabp11a mRNAs were elevated in fish fed the linolenic acid-rich or the low fat diets. In all cases, induction of the steady-state level of fabp mRNAs by dietary FAs correlated with induced levels of hnRNA for a given fabp gene. As such, up-regulation of the steady-state level of fabp mRNAs by FAs occurred at the level of initiation of transcription. None of the sister duplicates of these fabp genes exhibited an increase in their steady-state transcript levels in a specific tissue following feeding zebrafish any of the four experimental diets.

Conclusion

Differential induction of only one of the sister pair of duplicated fabp genes by FAs provides evidence to support the DDC model for retention of duplicated genes in the zebrafish genome by either subfunctionalization or neofunctionalization.

Gene and protein expression profiling of the fat-1 mouse brain

Polyunsaturated fatty acids (PUFAs) are essential structural components of all cell membranes and, more so, of the central nervous system. Several studies revealed that n-3 PUFAs possess anti-inflammatory actions and are useful in the treatment of dyslipidemia. These actions explain the beneficial actions of n-3 PUFAs in the management of cardiovascular diseases, inflammatory conditions, neuronal dysfunction, and cancer. But, the exact molecular targets of these beneficial actions of n-3 PUFAs are not known. Mice engineered to carry a fat-1 gene from Caenorhabditis elegans add a double bond into an unsaturated fatty acid hydrocarbon chain and convert n-6 to n-3 fatty acids. This results in an abundance of n-3 eicosapentaenoic acid and docosapentaenoic acid specifically in the brain and a reduction in n-6 fatty acids of these mice that can be used to evaluate the actions of n-3 PUFAs. Gene expression profile, RT-PCR and protein microarray studies in the hippocampus and whole brain of wild-type and fat-1 transgenic mice revealed that genes and proteins concerned with inflammation, apoptosis, neurotransmission, and neuronal growth and synapse formation are specifically modulated in fat-1 mice. These results may explain as to why n-3 PUFAs are of benefit in the prevention and treatment of diseases such as Alzheimer's disease, schizophrenia and other diseases associated with neuronal dysfunction, low-grade systemic inflammatory conditions, and bronchial asthma. Based on these data, it is evident that n-3 PUFAs act to modulate specific genes and formation of their protein products and thus, bring about their various beneficial actions.

Melatonin-induced gene expression changes and its preventive effects on adriamycin-induced lipid peroxidation in rat liver

Adriamycin (ADR) provokes lipid peroxidation process, while melatonin (MEL) is a free radical scavenger that has been found to protect against lipid peroxidation in vitro and in many experimental models. In the present study, the effects of ADR and the combination of ADR and MEL were analyzed on the modulation of fatty acid composition, lipid peroxidation and gene expression in rat liver. Sixty genes were selected for the study of relative gene expression changes in the liver. ADR treatment decreased the polyunsaturated fatty acids C22:6 n-3 and C20:4 n-6 in rat liver mitochondria. When the treatment of ADR was followed by MEL, decrease in these fatty acids could not be detected. A significant increase in lipid peroxidation was observed after administration of ADR, which was restored to control values by post-treatment with MEL. Gene expression profiles of ADR- versus ADR+MEL-treated rat livers indicated that both treatments induced significant changes. Quantitative real-time polymerase chain reaction analysis of 60 genes involved in oxidative stress revealed that cyp1b1, which is involved in electron transport, cyclin-dependent kinase inhibitor 1a that possesses cyclin-dependent protein kinase inhibitor activity, was induced at a more pronounced level in the ADR+MEL-treated samples than in the ADR-treated ones. Several genes having roles in heat-shock response were downregulated in MEL-treated animals, such as hsp40, hsp70 and hsp90 proteins reflecting the reduced oxidative stress in these animals. Global gene expression analysis will highlight the gene expression changes accompanying oxidative damage and its prevention in more details.

How dietary arachidonic- and docosahexaenoic- acid rich oils differentially affect the murine hepatic transcriptome

Introduction

Herein, we expand our previous work on the effects of long chain polyunsaturated fatty acids (LC-PUFA) on the murine hepatic transcriptome using novel statistical and bioinformatic approaches for evaluating microarray data. The analyses focuses on key differences in the transcriptomic response that will influence metabolism following consumption of FUNG (rich in 20:4n6), FISH (rich in 20:5n3, 22:5n3, and 22:6n3) and COMB, the combination of the two.

Results

Using a variance-stabilized F-statistic, 371 probe sets (out of 13 K probe sets in the Affymetrix Mu11K chip set) were changed by dietary treatment (P < 0.001). Relative to other groups, COMB had unique affects on murine hepatic transcripts involved in cytoskeletal and carbohydrate metabolism; whereas FUNG affected amino acid metabolism via CTNB1 signaling. All three diets affected transcripts linked to apoptosis and cell proliferation, with evidence FISH may have increased apoptosis and decreased cell proliferation via various transcription factors, kinases, and phosphatases. The three diets affected lipid transport, lipoprotein metabolism, and bile acid metabolism through diverse pathways. Relative to other groups, FISH activated cyps that form hydroxylated fatty acids known to affect vascular tone and ion channel activity. FA synthesis and delta 9 desaturation were down regulated by COMB relative to other groups, implying that a FA mixture of 20:4n6, 20:5n3, and 22:6n3 is most effective at down regulating synthesis, via INS1, SREBP, PPAR alpha, and TNF signaling. Heme synthesis and the utilization of heme for hemoglobin production were likely affected by FUNG and FISH. Finally, relative to other groups, FISH increased numerous transcripts linked to combating oxidative such as peroxidases, an aldehyde dehydrogenase, and heat shock proteins, consistent with the major LC-PUFA in FISH (20:5n3, 22:5n3, 22:6n3) being more oxidizable than the major fatty acids in FUNG (20:4n6).

Conclusion

Distinct transcriptomic, signaling cascades, and predicted affects on murine liver metabolism have been elucidated for 20:4n6-rich dietary oils, 22:6n3-rich oils, and a surprisingly distinct set of genes were affected by the combination of the two. Our results emphasize that the balance of dietary n6 and n3 LC-PUFA provided for infants and in nutritional and neutraceutical applications could have profoundly different affects on metabolism and cell signaling, beyond that previously recognized.

A cholesterol-enriched diet induces ultrastructural changes in retinal and macroglial rabbit cells

The purpose of this study was to ascertain whether the excess of cholesterol in rabbits induces ultrastructural retinal changes similar to those observed in human age-related macular degeneration (AMD). New Zealand rabbits were divided into two groups: Control (GO; n=10), fed standard diet for 8 months; hypercholesterolemic (G1; n=10), fed with 0.5% cholesterol-enriched diet for 8 months. Eyes were processed for transmission electron microscopy (TEM) and immunohistochemistry (anti-glial fibrillary acidic protein, GPAP). In comparison with GO, G1 exhibited alterations in all the retinal layers that were more intense in areas overlying altered retinal pigment epithelium (RPE). RPE changes showed no preferential location. In G1, Bruch's membrane was thicker as a result particle build-up in the collagen layers; the cytoplasm of RPE showed dense bodies, debris from cell membranes, vacuoles and numerous clumps of lipids; necrosis and apoptosis were detected in different retinal layers; Müller cells and astrocytes were reactive with instances of apoptosis and necrosis; some Müller cells filled up the empty spaces left by degenerated neurons in all retinal layers; some Müller cell nuclei were displaced to the nerve-fiber layer (NFL); epiretinal perivascular astrocytes contained drops of lipids; the NFL had very few astrocytes and the basal membranes of capillaries in the NFL was thicker. Excess cholesterol induces ultrastructural changes in the rabbit retina similar to those in human AMD. Given that lipid intake is most dependent on food composition, dietary regimen could help induce or prevent retinal disease.

Human apoB overexpression and a high-cholesterol diet differently modify the brain APP metabolism in the transgenic mouse model of atherosclerosis

Epidemiological and biochemical data suggest a link between the cholesterol metabolism, the amyloid precursor protein (APP) processing and the increased cerebral beta-amyloid (Abeta) deposition in Alzheimer's disease (AD). The individual and combined effects of a high-cholesterol (HC) diet and the overexpression of the human apoB-100 gene were therefore examined on the cerebral expression and processing of APP in homozygous apoB-100 transgenic mice [Tg (apoB(+/+))], a validated model of atherosclerosis. When fed with 2% cholesterol for 17 weeks, only the wild-type mice exhibited significantly increased APP695 (123%) and APP770 (138%) mRNA levels in the cortex. The HC diet-induced hypercholesterolemia significantly increased the APP isoform levels in the membrane-bound fraction, not only in the wild-type animals (114%), but also in the Tg apoB(+/+) group (171%). The overexpression of human apoB-100 gene by the liver alone reduced the brain APP isoform levels in the membrane-bound fraction (78%), whereas the levels were increased by the combined effect of HC and the overexpression of the human apoB-100 gene (134%). The protein kinase C and beta-secretase protein levels were not altered by the individual or combined effects of these two factors. Our data indicate that the two atherogenic factors, the HC diet and the overexpression of the human apoB-100 gene by the liver, could exert different effects on the processing and expression of APP in the mice brain.

Nutrigenomic approaches to study the effects of n-3 PUFA diet in the central nervous system

Deficiencies in essential, mainly omega-3 and omega-6 (n-3, n-6) long chain polyunsaturated fatty acids (LC-PUFA) result in visual and cognitive impairment and disturbances in mental functions in animals and could be the main reason for the increasing incidence of different mental disorders in humans. Traditional approaches cannot give us a detailed picture on how dietary lipids exert their effects, because they focus on only a few genes or biomarkers. Dietary lipids not only influence the biophysical state of the cell membranes but, via direct and indirect routes, they also act on multiple pathways including signalling and gene and protein activities. Therefore, to understand the molecular basis of the effects and roles of n-3 PUFA in the central nervous system global screening techniques such as DNA- or protein microarrays were used to assess the changes, in a global way, at the transcriptome and at the proteome level. With DNA microarrays we found that cholesterol and fish oil (high in PUFA) diets altered the expression of several genes involved in raft formation and membrane protrusions. By using protein microarrays we detected a decreased concentration of protein kinase C beta, gamma, phospholipase C gamma and other changes in the expression level of proteins involved in the signal transduction pathway in the brain in response to high cholesterol diet. Besides the known cellular effects of lipid nutritions (changing eicosanoid make up, effects on membrane fluidity and raft stability) it is now evident that dietary lipids influence gene and protein activity levels, protein modifications and probably play important role in modulating protein aggregation.

α-Linolenic acid does not contribute appreciably to docosahexaenoic acid within brain phospholipids of adult rats fed a diet enriched in docosahexaenoic acid

Adult male unanesthetized rats, reared on a diet enriched in both alpha-linolenic acid (alpha-LNA) and docosahexaenoic acid (DHA), were infused intravenously for 5 min with [1-(14)C]alpha-LNA. Timed arterial samples were collected until the animals were killed at 5 min and the brain was removed after microwaving. Plasma and brain lipid concentrations and radioactivities were measured. Within plasma lipids, > 99% of radioactivity was in the form of unchanged [1-(14)C]alpha-LNA. Eighty-six per cent of brain radioactivity at 5 min was present as beta-oxidation products, whereas the remainder was mainly in 'stable' phospholipid or triglyceride as alpha-LNA or DHA. Equations derived from kinetic modeling demonstrated that unesterified unlabeled alpha-LNA rapidly enters brain from plasma, but that its incorporation into brain phospholipid and triglyceride, as in the form of synthesized DHA, is < or = 0.2% of the amount that enters the brain. Thus, in rats fed a diet containing large amounts of both alpha-LNA and DHA, the alpha-LNA that enters brain from plasma largely undergoes beta-oxidation, and is not an appreciable source of DHA within brain phospholipids.