Whole-exome screening for primary congenital glaucoma in Lebanon.

PURPOSE: Mutations were previously identified in the CYP1B1 gene in six out of 18 Lebanese families (33%) with primary congenital glaucoma (PCG). The purpose of this study is to determine the frequency and type of pathogenic mutations in other genes and compare to other populations using whole-exome sequencing and perform genotype-phenotype correlations. METHODS: Twelve PCG patients previously negative for CYP1B1/MYOC mutations were subjected to whole-exome sequencing. Targeted screening for glaucoma-associated genes was performed. Candidate variants were verified by Sanger sequencing and evaluated in family members for segregation analysis and in 100 normal controls. Clinical correlations were established as to severity of disease presentation, course, and visual outcomes. RESULTS: Six mutations in known PCG-causing genes were identified in five patients: homozygous mutations in CYP1B1 (p.R368G), LTBP2 (p.E1013G), and TEK (p.T693I), and heterozygous mutations in FOXC1 (p.Q92*), TEK (c.3201-1 G>A), ANGPT1 (p.K186N), and CYP1B1 (p.R368G). Two patients, negative for CYP1B1 in the previous study, were revealed positive in the current study, due to different sets of primers and PCR conditions. Potentially damaging variants were noted in several candidate genes. Except for FOXC1 mutations, all genetic variants described here are novel. Intra-ocular pressure and final optic nerve cup-to-disc ratio were highest in the patient with three mutations in LTBP2/TEK/ANGPT1 genes. CONCLUSION: This study provides new data on the spectrum of mutations of PCG in Lebanon. This highlights the genetic heterogeneity of the Lebanese population, noted for high rates of consanguinity in 50% in this cohort. This study emphasizes the importance of whole-exome sequencing in elucidating new candidate genes for PCG in the Lebanese.

Sex differences in gene expression with galactosylceramide treatment in Cln3Δex7/8 mice.

BACKGROUND: CLN3 disease is caused by mutations in the CLN3 gene. The purpose of this study is to discern global expression patterns reflecting therapeutic targets in CLN3 disease. METHODS: Differential gene expression in vehicle-exposed mouse brain was determined after intraperitoneal vehicle/Galactosylceramide (GalCer) injections for 40 weeks with GeneChip Mouse Genome 430 2.0 arrays. RESULTS: Analysis identified 66 genes in male and 30 in female brains differentially expressed in GalCer-treated versus vehicle-exposed Cln3Δex7/8 mice. Gene ontology revealed aberrations of biological function including developmental, cellular, and behavioral processes. GalCer treatment altered pathways of long-term potentiation/depression, estrogen signaling, synaptic vesicle cycle, ErbB signaling, and prion diseases in males, but prolactin signaling, selenium compound metabolism and steroid biosynthesis in females. Gene-gene network analysis highlighted networks functionally pertinent to GalCer treatment encompassing motor dysfunction, neurodegeneration, memory disorder, inflammation and astrogliosis in males, and, cataracts, inflammation, astrogliosis, and anxiety in females. CONCLUSIONS: This study sheds light on global expression patterns following GalCer treatment of Cln3Δex7/8 mice. Understanding molecular effects of GalCer on mouse brain gene expression, paves the way for personalized strategies for treating this debilitating disease in humans.

Exogenous Flupirtine as Potential Treatment for CLN3 Disease.

CLN3 disease is a fatal neurodegenerative disorder affecting children. Hallmarks include brain atrophy, accelerated neuronal apoptosis, and ceramide elevation. Treatment regimens are supportive, highlighting the importance of novel, disease-modifying drugs. Flupirtine and its new allyl carbamate derivative (compound 6) confer neuroprotective effects in CLN3-deficient cells. This study lays the groundwork for investigating beneficial effects in Cln3Δex7/8 mice. WT/Cln3Δex7/8 mice received flupirtine/compound 6/vehicle for 14 weeks. Short-term effect of flupirtine or compound 6 was tested using a battery of behavioral testing. For flupirtine, gene expression profiles, astrogliosis, and neuronal cell counts were determined. Flupirtine improved neurobehavioral parameters in open field, pole climbing, and Morris water maze tests in Cln3Δex7/8 mice. Several anti-apoptotic markers and ceramide synthesis/degradation enzymes expression was dysregulated in Cln3Δex7/8 mice. Flupirtine reduced astrogliosis in hippocampus and motor cortex of male and female Cln3Δex7/8 mice. Flupirtine increased neuronal cell counts in male mice. The newly synthesized compound 6 showed promising results in open field and pole climbing. In conclusion, flupirtine improved behavioral, neuropathological and biochemical parameters in Cln3Δex7/8 mice, paving the way for potential therapies for CLN3 disease.

Developmental Comparison of Ceramide in Wild-Type and Cln3 Δex7/8 Mouse Brains and Sera.

CLN3 disease is a neurodevelopmental disease leading to early visual failure, motor decline, and death. CLN3 pathogenesis has been linked to dysregulation of ceramide, a key intracellular messenger impacting various biological functions. Ceramide is upregulated in brains of CLN3 patients and activates apoptosis. Ceramide levels over the lifespan of WT and Cln3 Δex7/8 mice were measured using the DGK assay. Ceramide subspecies were determined by LC-MS. Ceramide synthesis enzymes and pre- and post-synaptic mRNA expression was measured in Cln3 Δex7/8 and normal mouse brains. Neuronal cell death was established by PARP cleavage and Caspases 3/6/9 and cytochrome C mRNA expression in Cln3 Δex7/8 and normal mouse brains. In WT mouse, a ceramide peak was noted at 3 weeks of age. The absence of this peak in Cln3 Δex7/8 mice might be related to early disease pathogenesis. Increase of ceramide in Cln3 Δex7/8 mouse brain at 24 weeks of age precedes neuronal apoptosis. The correlation between serum and brain ceramide in WT mice, and dysregulation of ceramide in serum and brain of Cln3 Δex7/8 mice, and the significant increase in ceramide in Cln3 Δex7/8 mouse brains and sera argue for use of easily accessible serum ceramide levels to track response to novel therapies in human CLN3 disease.

Candidate Genes for Inherited Autism Susceptibility in the Lebanese Population.

Autism spectrum disorder (ASD) is characterized by ritualistic-repetitive behaviors and impaired verbal/non-verbal communication. Many ASD susceptibility genes implicated in neuronal pathways/brain development have been identified. The Lebanese population is ideal for uncovering recessive genes because of shared ancestry and a high rate of consanguineous marriages. Aims here are to analyze for published ASD genes and uncover novel inherited ASD susceptibility genes specific to the Lebanese. We recruited 36 ASD families (ASD: 37, unaffected parents: 36, unaffected siblings: 33) and 100 unaffected Lebanese controls. Cytogenetics 2.7 M Microarrays/CytoScan™ HD arrays allowed mapping of homozygous regions of the genome. The CNTNAP2 gene was screened by Sanger sequencing. Homozygosity mapping uncovered DPP4, TRHR, and MLF1 as novel candidate susceptibility genes for ASD in the Lebanese. Sequencing of hot spot exons in CNTNAP2 led to discovery of a 5 bp insertion in 23/37 ASD patients. This mutation was present in unaffected family members and unaffected Lebanese controls. Although a slight increase in number was observed in ASD patients and family members compared to controls, there were no significant differences in allele frequencies between affecteds and controls (C/TTCTG: γ2 value = 0.014; p = 0.904). The CNTNAP2 polymorphism identified in this population, hence, is not linked to the ASD phenotype.

Gene expression profiling of breast cancer in Lebanese women.

Breast cancer is commonest cancer in women worldwide. Elucidation of underlying biology and molecular pathways is necessary for improving therapeutic options and clinical outcomes. Molecular alterations in breast cancer are complex and involve cross-talk between multiple signaling pathways. The aim of this study is to extract a unique mRNA fingerprint of breast cancer in Lebanese women using microarray technologies. Gene-expression profiles of 94 fresh breast tissue samples (84 cancerous/10 non-tumor adjacent samples) were analyzed using GeneChip Human Genome U133 Plus 2.0 arrays. Quantitative real-time PCR was employed to validate candidate genes. Differentially expressed genes between breast cancer and non-tumor tissues were screened. Significant differences in gene expression were established for COL11A1/COL10A1/MMP1/COL6A6/DLK1/S100P/CXCL11/SOX11/LEP/ADIPOQ/OXTR/FOSL1/ACSBG1 and C21orf37. Pathways/diseases representing these genes were retrieved and linked using PANTHER®/Pathway Studio®. Many of the deregulated genes are associated with extracellular matrix, inflammation, angiogenesis, metastasis, differentiation, cell proliferation and tumorigenesis. Characteristics of breast cancers in Lebanese were compared to those of women from Western populations to explain why breast cancer is more aggressive and presents a decade earlier in Lebanese victims. Delineating molecular mechanisms of breast cancer in Lebanese women led to key genes which could serve as potential biomarkers and/or novel drug targets for breast cancer.

RYR2, PTDSS1 and AREG genes are implicated in a Lebanese population-based study of copy number variation in autism.

Autism Spectrum Disorders (ASDs) are a group of neurodevelopmental disorders characterized by ritualistic-repetitive behaviors and impaired verbal and non-verbal communication. Objectives were to determine the contribution of genetic variation to ASDs in the Lebanese. Affymetrix Cytogenetics Whole-Genome 2.7 M and CytoScan(™) HD Arrays were used to detect CNVs in 41 Lebanese autistic children and 35 non-autistic, developmentally delayed and intellectually disabled patients. 33 normal participants were used as controls. 16 de novo CNVs and 57 inherited CNVs, including recognized pathogenic 16p11.2 duplications and 2p16.3 deletions were identified. A duplication at 1q43 classified as likely pathogenic encompasses RYR2 as a potential ASD candidate gene. This previously identified CNV has been classified as both pathogenic, and, of uncertain significance. A duplication of unknown significance at 10q11.22, proposed as a modulator for phenotypic disease expression in Rett syndrome, was also identified. The novel potential autism susceptibility genes PTDSS1 and AREG were uncovered and warrant further genetic and functional analyses. Previously described and novel genetic targets in ASD were identified in Lebanese families with autism. These findings may lead to improved diagnosis of ASDs and informed genetic counseling, and may also lead to untapped therapeutic targets applicable to Lebanese and non-Lebanese patients.

Association between CLN3 (Neuronal Ceroid Lipofuscinosis, CLN3 Type) Gene Expression and Clinical Characteristics of Breast Cancer Patients.

Breast cancer is the most common cancer in women worldwide. Elucidation of underlying biology and molecular pathways is necessary for improving therapeutic options and clinical outcomes. CLN3 protein (CLN3p), deficient in neurodegenerative CLN3 disease is anti-apoptotic, and defects in the CLN3 gene cause accelerated apoptosis of neurons in CLN3 disease and up-regulation of ceramide. Dysregulated apoptotic pathways are often implicated in the development of the oncogenic phenotype. Predictably, CLN3 mRNA expression and CLN3 protein were up-regulated in a number of human and murine breast cancer-cell lines. Here, we determine CLN3 expression in non-tumor vs. tumor samples from fresh and formalin-fixed/paraffin-embedded (FFPE) breast tissue and analyze the association between CLN3 overexpression and different clinicopathological characteristics of breast cancer patients. Additionally, gene expression of 28 enzymes involved in sphingolipid metabolism was determined. CLN3 mRNA is overexpressed in tumor vs. non-tumor breast tissue from FFPE and fresh samples, as well as in mouse MCF7 breast cancer compared to MCF10A normal cells. Of the clinicopathological characteristics of tumor grade, age, menopause status, estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2), only absence of HER2 expression correlated with CLN3 overexpression. Sphingolipid genes for ceramide synthases 2 and 6 (CerS2; CerS6), delta(4)-desaturase sphingolipid 2 (DEGS2), and acidic sphingomyelinase (SMPD1) displayed higher expression levels in breast cancer vs. control tissue, whereas ceramide galactosyltransferase (UGT8) was underexpressed in breast cancer samples. CLN3 may be a novel molecular target for cancer drug discovery with the goal of modulation of ceramide pathways.

Prediabetic changes in gene expression induced by aspartame and monosodium glutamate in Trans fat-fed C57Bl/6 J mice.

BACKGROUND: The human diet has altered markedly during the past four decades, with the introduction of Trans hydrogenated fat, which extended the shelf-life of dietary oils and promoted a dramatic increase in elaidic acid (Trans-18.1) consumption. Food additives such as monosodium glutamate (MSG) and aspartame (ASP) were introduced to increase food palatability and reduce caloric intake. Nutrigenomics studies in small-animal models are an established platform for analyzing the interactions between various macro- and micronutrients. We therefore investigated the effects of changes in hepatic and adipose tissue gene expression induced by the food additives ASP, MSG or a combination of both additives in C57Bl/6 J mice fed a Trans fat-enriched diet. METHODS: Hepatic and adipose tissue gene expression profiles, together with body characteristics, glucose parameters, serum hormone and lipid profiles were examined in C57Bl/6 J mice consuming one of the following four dietary regimens, commencing in utero via the mother's diet: [A] Trans fat (TFA) diet; [B] MSG + TFA diet; [C] ASP + TFA diet; [D] ASP + MSG + TFA diet. RESULTS: Whilst dietary MSG significantly increased hepatic triglyceride and serum leptin levels in TFA-fed mice, the combination of ASP + MSG promoted the highest increase in visceral adipose tissue deposition, serum free fatty acids, fasting blood glucose, HOMA-IR, total cholesterol and TNFα levels. Microarray analysis of significant differentially expressed genes (DEGs) showed a reduction in hepatic and adipose tissue PPARGC1a expression concomitant with changes in PPARGC1a-related functional networks including PPARα, δ and γ. We identified 73 DEGs common to both adipose and liver which were upregulated by ASP + MSG in Trans fat-fed mice; and an additional 51 common DEGs which were downregulated. CONCLUSION: The combination of ASP and MSG may significantly alter adiposity, glucose homeostasis, hepatic and adipose tissue gene expression in TFA-fed C57Bl/6 J mice.

Interactive effects of neonatal exposure to monosodium glutamate and aspartame on glucose homeostasis.

BACKGROUND: Recent evidence suggests that the effects of certain food additives may be synergistic or additive. Aspartame (ASP) and Monosodium Glutamate (MSG) are ubiquitous food additives with a common moiety: both contain acidic amino acids which can act as neurotransmitters, interacting with NMDA receptors concentrated in areas of the Central Nervous System regulating energy expenditure and conservation. MSG has been shown to promote a neuroendocrine dysfunction when large quantities are administered to mammals during the neonatal period. ASP is a low-calorie dipeptide sweetener found in a wide variety of diet beverages and foods. However, recent reports suggest that ASP may promote weight gain and hyperglycemia in a zebrafish nutritional model. METHODS: We investigated the effects of ASP, MSG or a combination of both on glucose and insulin homeostasis, weight change and adiposity, in C57BL/6 J mice chronically exposed to these food additives commencing in-utero, compared to an additive-free diet. Pearson correlation analysis was used to investigate the associations between body characteristics and variables in glucose and insulin homeostasis. RESULTS: ASP alone (50 mg/Kgbw/day) caused an increase in fasting blood glucose of 1.6-fold, together with reduced insulin sensitivity during an Insulin Tolerance Test (ITT) P < 0.05. Conversely MSG alone decreased blood triglyceride and total cholesterol (T-CHOL) levels. The combination of MSG (120 mg/Kgbw/day) and ASP elevated body weight, and caused a further increase in fasting blood glucose of 2.3-fold compared to Controls (prediabetic levels); together with evidence of insulin resistance during the ITT (P < 0.05). T-CHOL levels were reduced in both ASP-containing diets in both genders. Further analysis showed a strong correlation between body weight at 6 weeks, and body weight and fasting blood glucose levels at 17 weeks, suggesting that early body weight may be a predictor of glucose homeostasis in later life. CONCLUSIONS: Aspartame exposure may promote hyperglycemia and insulin intolerance. MSG may interact with aspartame to further impair glucose homeostasis. This is the first study to ascertain the hyperglycemic effects of chronic exposure to a combination of these commonly consumed food additives; however these observations are limited to a C57BL/6 J mouse model. Caution should be applied in extrapolating these findings to other species.

Gender dimorphism in aspartame-induced impairment of spatial cognition and insulin sensitivity.

Previous studies have linked aspartame consumption to impaired retention of learned behavior in rodents. Prenatal exposure to aspartame has also been shown to impair odor-associative learning in guinea pigs; and recently, aspartame-fed hyperlipidemic zebrafish exhibited weight gain, hyperglycemia and acute swimming defects. We therefore investigated the effects of chronic lifetime exposure to aspartame, commencing in utero, on changes in blood glucose parameters, spatial learning and memory in C57BL/6J mice. Morris Water Maze (MWM) testing was used to assess learning and memory, and a random-fed insulin tolerance test was performed to assess glucose homeostasis. Pearson correlation analysis was used to investigate the associations between body characteristics and MWM performance outcome variables. At 17 weeks of age, male aspartame-fed mice exhibited weight gain, elevated fasting glucose levels and decreased insulin sensitivity compared to controls (P<0.05). Females were less affected, but had significantly raised fasting glucose levels. During spatial learning trials in the MWM (acquisition training), the escape latencies of male aspartame-fed mice were consistently higher than controls, indicative of learning impairment. Thigmotactic behavior and time spent floating directionless was increased in aspartame mice, who also spent less time searching in the target quadrant of the maze (P<0.05). Spatial learning of female aspartame-fed mice was not significantly different from controls. Reference memory during a probe test was affected in both genders, with the aspartame-fed mice spending significantly less time searching for the former location of the platform. Interestingly, the extent of visceral fat deposition correlated positively with non-spatial search strategies such as floating and thigmotaxis, and negatively with time spent in the target quadrant and swimming across the location of the escape platform. These data suggest that lifetime exposure to aspartame, commencing in utero, may affect spatial cognition and glucose homeostasis in C57BL/6J mice, particularly in males.

Nutrigenomics of hepatic steatosis in a feline model: effect of monosodium glutamate, fructose, and Trans-fat feeding.

Nonalcoholic fatty liver disease begins with a relatively benign hepatic steatosis, often associated with increased adiposity, but may progress to a more severe nonalcoholic steatohepatitis with inflammation. A subset of these patients develops progressive fibrosis and ultimately cirrhosis. Various dietary components have been shown to contribute to the development of liver disease, including fat, sugars, and neonatal treatment with high doses of monosodium glutamate (MSG). However, rodent models of progressive disease have been disappointing, and alternative animal models of diet-induced liver disease would be desirable, particularly if they contribute to our knowledge of changes in gene expression as a result of dietary manipulation. The domestic cat has previously been shown to be an appropriate model for examining metabolic changes-associated human diseases such as diabetes. Our aim was therefore to compare changes in hepatic gene expression induced by dietary MSG, with that of a diet containing Trans-fat and high fructose corn syrup (HFCS), using a feline model. MSG treatment increased adiposity and promoted hepatic steatosis compared to control (P < 0.05). Exposure to Trans-fat and HFCS promoted hepatic fibrosis and markers of liver dysfunction. Affymetrix microarray analysis of hepatic gene expression showed that dietary MSG promoted the expression of genes involved in cholesterol and steroid metabolism. Conversely, Trans-fat and HFCS feeding promoted the expression of genes involved in lipolysis, glycolysis, liver damage/regeneration, and fibrosis. Our feline model examining gene-diet interactions (nutrigenomics) demonstrates how dietary MSG, Trans-fat, and HFCS may contribute to the development of hepatic steatosis.

Sex-dimorphism in cardiac nutrigenomics: effect of trans fat and/or monosodium glutamate consumption.

BACKGROUND: A paucity of information on biological sex-specific differences in cardiac gene expression in response to diet has prompted this present nutrigenomics investigation. Sexual dimorphism exists in the physiological and transcriptional response to diet, particularly in response to high-fat feeding. Consumption of Trans-fatty acids (TFA) has been linked to substantially increased risk of heart disease, in which sexual dimorphism is apparent, with males suffering a higher disease rate. Impairment of the cardiovascular system has been noted in animals exposed to Monosodium Glutamate (MSG) during the neonatal period, and sexual dimorphism in the growth axis of MSG-treated animals has previously been noted. Processed foods may contain both TFA and MSG. METHODS: We examined physiological differences and changes in gene expression in response to TFA and/or MSG consumption compared to a control diet, in male and female C57BL/6J mice. RESULTS: Heart and % body weight increases were greater in TFA-fed mice, who also exhibited dyslipidemia (P < 0.05). Hearts from MSG-fed females weighed less than males (P < 0.05). 2-factor ANOVA indicated that the TFA diet induced over twice as many cardiac differentially expressed genes (DEGs) in males compared to females (P < 0.001); and 4 times as many male DEGs were downregulated including Gata4, Mef2d and Srebf2. Enrichment of functional Gene Ontology (GO) categories were related to transcription, phosphorylation and anatomic structure (P < 0.01). A number of genes were upregulated in males and downregulated in females, including pro-apoptotic histone deacetylase-2 (HDAC2). Sexual dimorphism was also observed in cardiac transcription from MSG-fed animals, with both sexes upregulating approximately 100 DEGs exhibiting sex-specific differences in GO categories. A comparison of cardiac gene expression between all diet combinations together identified a subset of 111 DEGs significant only in males, 64 DEGs significant in females only, and 74 transcripts identified as differentially expressed in response to dietary manipulation in both sexes. CONCLUSION: Our model identified major changes in the cardiac transcriptional profile of TFA and/or MSG-fed mice compared to controls, which was reflected by significant differences in the physiological profile within the 4 diet groups. Identification of sexual dimorphism in cardiac transcription may provide the basis for sex-specific medicine in the future.

Effect of trans-fat, fructose and monosodium glutamate feeding on feline weight gain, adiposity, insulin sensitivity, adipokine and lipid profile.

The incidence of obesity and type 2 diabetes mellitus (T2DM) is increasing, and new experimental models are required to investigate the diverse aspects of these polygenic diseases, which are intimately linked in terms of aetiology. Feline T2DM has been shown to closely resemble human T2DM in terms of its clinical, pathological and physiological features. Our aim was to develop a feline model of diet-induced weight gain, adiposity and metabolic deregulation, and to examine correlates of weight and body fat change, insulin homeostasis, lipid profile, adipokines and clinical chemistry, in order to study associations which may shed light on the mechanism of diet-induced metabolic dysregulation. We used a combination of partially hydrogenated vegetable shortening and high-fructose corn syrup to generate a high-fat-high-fructose diet. The effects of this diet were compared with an isoenergetic standard chow, either in the presence or absence of 1.125 % dietary monosodium glutamate (MSG). Dual-energy X-ray absorptiometry body imaging and a glucose tolerance test were performed. The present results indicate that dietary MSG increased weight gain and adiposity, and reduced insulin sensitivity (P < 0.05), whereas high-fat-high-fructose feeding resulted in elevated cortisol and markers of liver dysfunction (P < 0.01). The combination of all three dietary constituents resulted in lower insulin levels and elevated serum ß-hydroxybutyrate and cortisol (P < 0.05). This combination also resulted in a lower first-phase insulin release during glucose tolerance testing (P < 0.001). In conclusion, markers of insulin deregulation and metabolic dysfunction associated with adiposity and T2DM can be induced by dietary factors in a feline model.

The I allele of the angiotensin converting enzyme I/D polymorphism confers protection against coronary artery disease.

BACKGROUND: Mutations in genes regulating lipid metabolism, vasoactivity, and coagulation are important modulators of coronary artery disease (CAD). OBJECTIVE: This study investigated the association between allelic variants of the angiotensin converting enzyme (ACE), methytetrahydrofolate reductase, plasminogen activator inhibitor-1 and factor V genes and CAD. METHODS: Clinical, biochemical, and angiographic information were collected from 300 patients who underwent cardiac catheterization and their DNA was genotyped by restriction fragment length polymorphism. RESULTS: The frequency of the D allele of the ACE gene was significantly higher than the I allele in patients with more than 70% stenosis in any vessel. Among patients with more than 70% stenosis, carriers of the D allele were 2.8 times more likely to be males. The presence of the ACE I allele was negatively associated with CAD with (P=0.02 ,OR=0.38.) CONCLUSION: This study describes a protective role of the ACE I allele in individuals who may be at risk of developing CAD.

Effect of dietary monosodium glutamate on HFCS-induced hepatic steatosis: expression profiles in the liver and visceral fat.

It has previously been shown that patients with nonalcoholic fatty liver disease (NAFLD) exhibit alterations in both hepatic and adipose tissue metabolism, and the dietary factors that contribute to the pathogenesis of NAFLD are likely to be multifactorial. Using C57BL/6J mice, we examined whether chronic exposure to low-dose dietary monosodium glutamate (MSG), high-fructose corn syrup (HFCS), or a combination of the two, vs. control would affect metabolism and hepatic and visceral fat gene expression in adult male progeny. A maternal diet containing 20% HFCS and/or dietary MSG (97.2 +/- 6.3 mg/kg body weight (bw), provided in the drinking water) was offered ad libitum from 3 weeks before mating, and continued throughout gestation and weaning until the progeny reached 32 weeks of age. Liver and abdominal fat gene expression was compared with control animals fed isocaloric standard chow under identical conditions. HFCS induced hepatic steatosis and increased the expression of genes involved in carbohydrate and lipid metabolism. Conversely, dietary MSG elevated serum free fatty acids (FFAs), triglycerides (TGs), high-density lipoprotein-cholesterol (HDL-C), and insulin, together with the expression of hepatic genes involved in lipid metabolism and bile synthesis. The HFCS+MSG combination elevated hepatic TGs, serum FFAs, and TG levels. In visceral white adipose tissue, both MSG and HFCS diets increased the expression of transcription factor Srebf2 and decreased expression of Ppargc1a, while downregulating the expression of mitochondrial respiratory chain components. MSG increased the expression of several genes implicated in adipocytes differentiation. We hypothesize that HFCS may promote hepatic steatosis, whereas dietary MSG induces dyslipidemia and markers of insulin resistance.

Dietary trans-fat combined with monosodium glutamate induces dyslipidemia and impairs spatial memory.

AIMS: Recent evidence suggests that intake of excessive dietary fat, particularly saturated fat and trans-hydrogenated oils (trans-fatty acids: TFA) can impair learning and memory. Central obesity, which can be induced by neonatal injections of monosodium Glutamate (MSG), also impairs learning and memory. To further clarify the effects of dietary fat and MSG, we treated C57BL/6J mice with either a TFA-enriched diet, dietary MSG, or a combination of both and examined serum lipid profile and spatial memory compared to mice fed standard chow. Spatial learning was assessed at 6, 16 and 32 weeks of age in a Morris Water Maze (MWM). The subjects were given four days of training to find a hidden platform and a fifth day of reversal learning, in which the platform was moved to a new location. RESULTS: The TFA+MSG combination caused a central adiposity that was accompanied by impairment in locating the hidden platform in the MWM. Females in the TFA+MSG group showed a greater impairment compared to the other diet groups, and also showed elevated levels of fasting serum LDL-C and T-CHOL:HDL-C ratio, together with the lowest levels of HDL-C. Similarly, males in the TFA+MSG diet group were less successful than control mice at locating the hidden platform and had the highest level of abdominal adiposity and elevated levels of fasting serum LDL-C. CONCLUSION: Dietary trans-fat combined with MSG increased central adiposity, promoted dyslipidemia and impaired spatial learning.

Diabetes of the liver: the link between nonalcoholic fatty liver disease and HFCS-55.

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity and insulin resistance. It is also a predisposing factor for type 2 diabetes. Dietary factors are believed to contribute to all three diseases. NAFLD is characterized by increased intrahepatic fat and mitochondrial dysfunction, and its etiology may be attributed to excessive fructose intake. Consumption of high fructose corn syrup-55 (HFCS-55) stands at up to 15% of the average total daily energy intake in the United States, and is linked to weight gain and obesity. The aim of this study was to establish whether HFCS-55 could contribute to the pathogenesis of NAFLD, by examining the effects of HFCS-55 on hepatocyte lipogenesis, insulin signaling, and cellular function, in vitro and in vivo. Exposure of hepatocytes to HFCS-55 caused a significant increase in hepatocellular triglyceride (TG) and lipogenic proteins. Basal production of reactive oxygen metabolite (ROM) was increased, together with a decreased capacity to respond to an oxidative challenge. HFCS-55 induced a downregulation of the insulin signaling pathway, as indicated by attenuated (ser473)phosphorylation of AKT1. The c-Jun amino-terminal kinase (JNK), which is intimately linked to insulin resistance, was also activated; and this was accompanied by an increase in endoplasmic reticulum (ER) stress and intracellular free calcium perturbation. Hepatocytes exposed to HFCS-55 exhibited mitochondrial dysfunction and released cytochrome C (CytC) into the cytosol. Hepatic steatosis and mitochondrial disruption was induced in vivo by a diet enriched with 20% HFCS 55; accompanied by hypoadiponectinemia and elevated fasting serum insulin and retinol-binding protein-4 (RBP4) levels. Taken together our findings indicate a potential mechanism by which HFCS-55 may contribute to the pathogenesis of NAFLD.

Effect of dietary monosodium glutamate on trans fat-induced nonalcoholic fatty liver disease.

The effects of dietary monosodium glutamate (MSG) on trans-fatty acid (TFA)-induced nonalcoholic fatty liver disease (NAFLD) are addressed in an animal model. We used Affymetrix microarray analysis to investigate hepatic gene expression and the contribution of visceral white adipose tissue (WAT) to diet-induced NAFLD. Trans-fat feeding increased serum leptin, FFA, HDL-cholesterol (HDL-C), and total cholesterol (T-CHOL) levels, while robustly elevating the expression of genes involved in hepatic lipogenesis, including the transcription factor sterol-regulatory element binding protein 1c. Histological examination revealed hepatic macrosteatosis in TFA-fed animals. Conversely, dietary MSG at doses similar to human average daily intake caused hepatic microsteatosis and the expression of beta-oxidative genes. Serum triglyceride, FFA, and insulin levels were elevated in MSG-treated animals. The abdominal cavities of TFA- or MSG-treated animals had increased WAT deposition compared with controls. Microarray analysis of WAT gene expression revealed increased lipid biosynthetic gene expression, together with a 50% decrease in the key transcription factor Ppargc1a. A combination of TFA+MSG resulted in the highest levels of serum HDL-C, T-CHOL, and leptin. Microarray analysis of TFA+MSG-treated livers showed elevated expression of markers of hepatic inflammation, lipid storage, cell damage, and cell cycle impairment. TFA+MSG mice also had a high degree of WAT deposition and lipogenic gene expression. Levels of Ppargc1a were further reduced to 25% by TFA+MSG treatment. MSG exacerbates TFA-induced NAFLD.

WFS1 mutations are frequent monogenic causes of juvenile-onset diabetes mellitus in Lebanon.

Most cases of juvenile-onset diabetes (JOD) are diagnosed as type 1 diabetes (T1D), for which genetic studies conducted in outbred Caucasian populations support the concept of multifactorial inheritance. However, this view may be partly challenged in particular population settings. In view of the suggestive evidence for a high prevalence of Wolfram syndrome (WFS) in Lebanon, the phenotypic variability associated with WFS1 mutations, and the high consanguinity rate in Lebanon, we aimed to evaluate the contribution of WFS1 mutations as monogenic determinants to JOD in Lebanon. We performed a family-based genetic study, with linkage analysis followed by systematic mutation screening of WFS1 exons in all JOD probands. The study population consisted of an unbiased recruitment of all juvenile-onset insulin-dependent diabetic patients from a specialized diabetes pediatric clinic in Beirut, Lebanon. Homozygous or compound heterozygous WFS1 mutations were found in 22 of the 399 JOD probands (5.5%), resulting in WFS (17 probands) or in non-syndromic non-autoimmune diabetes mellitus (DM, five probands). These accounted for 12.1% (21/174) of probands in consanguineous families, compared with 0.4% (1/225) in non-consanguineous families. Of the 38 patients identified with homozygous or compound heterozygous WFS1 mutations, 11 (29%) had non-syndromic DM, all of whom carried a particular WFS1 mutation, WFS1(LIB), encoding a protein with an extended C-terminal domain. This mutation resulted in a delayed onset or absence of extrapancreatic features. These results underscore the major impact of population-specific factors, such as population-specific mutations and founder effects, and family structure in the genetic determinism of JOD.