The Role of Parkin in Rat Pancreatic Beta Cells Fate.

Parkin is a member of the mitochondrial quality control system that plays a major role in mitophagy. Although the loss of function mutations in the Parkin gene has been associated with the Familial Parkinson's phenotype, research in recent years points out that Parkin's function is not limited to neurodegenerative diseases. Parkin's function impressing key cellular quality control mechanisms, including the ubiquitin-proteasome and autophagy-lysosome systems, makes it an important player in the maintenance of cellular homeostasis. In this study, we investigated whether Parkin affects cell viability and ER stress responses under lipotoxic conditions in INS-1E cells. Our results may suggest that silencing Parkin may affect autophagy in addition to apoptosis.  We also showed that Parkin may have a protective effect against lipo-toxic effects in INS-1E cells. Consistent with previous studies, we observed that stress responses were different for high and low palmitic acid doses. The Parkin being inhibited under high-dose PA treatment and active under low-dose PA treatment indicate that regulation of stress responses is controlled by environmental conditions. Our preliminary findings may suggest that in low lipotoxic conditions, Parkin affects the ER stress response by modulating Chop activity and Ca2+ release from the ER to the cytoplasm.

A Lipotoxic Medium Decreases the Number of Lipid Droplets in ß Cells: One Possible Explanation of the ß-Cell Failure in Patients With Hyperlipidemia Receiving Tacrolimus.

OBJECTIVES: Dyslipidemia is a risk factor for post- transplant diabetes mellitus, especially in patients who are taking tacrolimus. Although lipotoxicity of dyslipidemia leads to ß-cell failure, the handling of lipids by ß cells is a mystery in molecular endocrinology. Likewise, lipid droplet homeostasis is appreciated as a key component of lipid metabolism in cells like hepatocytes, but its role in ß cells remains to be elucidated. MATERIALS AND METHODS: To evaluate the morphologic changes in ß cells with special focus on lipid droplets, we evaluated electron micrographs under metabolic stress conditions of glucotoxicity, lipotoxicity, and glucolipotoxicity in isolated rat insulinoma INS-1E ß cells. Cells were treated with palmitic acid (0.5 mM), glucose (33 mM), or both for 16 hours, after which morphologic changes were observed with an electron microscope. RESULTS: Many lipid droplets were observed in the cytoplasm of healthy ß cells in the control group (no treatment). Lipid droplets were also visible in the cytosol, and the cytoplasm was rich in organelles and insulin vesicles under high glucose stimulation. However, after treatment with palmitic acid, almost no lipid droplets were observed. Endocrine vesicles were also depleted, with severe morphologic disruption of other organelles. Under glucolipotoxic conditions, ß cells showed a decreased number of lipid droplets and insulin vesicles compared with controls. CONCLUSIONS: Lipid droplet dynamics seemed important in the homeostasis of ß-cell metabolism. In this preliminary study, healthy ß cells appeared rich in lipid droplets under normal conditions. However, lipotoxicity depleted and glucolipotoxicity decreased the number of lipid droplets in ß cells. Because dyslipidemia causing lipotoxicity is one of the most frequent metabolic problems in transplant patients and increases risk of posttransplant diabetes mellitus, understanding the mystery of lipid droplets in ß cells and the pathophysiology of diabetes in transplant patients is important, especially for those taking tacrolimus.

Beta-Cell Golgi Stress Response to Lipotoxicity and Glucolipotoxicity: A Preliminary Study of a Potential Mechanism of Beta-Cell Failure in Posttransplant Diabetes and Intraportal Islet Transplant.

OBJECTIVES: Lipotoxicity and glucolipotoxicity are among the mostimportanttriggers of beta-cell failure in patients with type 2 and posttransplant diabetes. Because the Golgi apparatus is a vital organelle in secretory cells like beta cells, its behavior under stress conditions determines the cell's functional capacity. MATERIALS AND METHODS: To mimic lipotoxicity and glucolipotoxicity as metabolic stresses for beta-cell failure, rat insulinoma INS-1E cells were treated with palmitic acid, glucose, or both. Cells were cultured in the presence of 5.0, 16.7, or 33 mM glucose with or without 0.5 mM palmitic acid for 8, 16, 24, and 48 hours. Incubation in the presence of any of the 3 concentrations of glucose with 0.5 mM palmitic acid provided glucolipotoxicity. In addition to the endoplasmic reticulum stress marker (Hspa5), we evaluated changes in Golgi function under experimental metabolic stresses. In doing this, we measured expression levels of the genes coding Golgi structural proteins (Acbd3,Golga2, and Arf1), Golgi glycosylation enzymes sialyltransferaz10 and sialyltransferase 1 (St3gal1), and Golgi stress mediators (Creb3 and Arf4). RESULTS: Golgi responded to lipotoxicity and glucolipotoxicity by increasing the expression of St3gal1 (P = .05 in both conditions) and Creb3 (P = .022 and P = .01, respectively). The Arf4 gene transcript also increased in glucolipotoxic media (P = .03). Glucotoxicity alone did not induce a change in the transcript levels of Creb3 and Arf4. Lipotoxicity and glucolipotoxicity induced Creb3 and Arf4 expression, which are important Golgi stress response mediators leading to apoptosis. CONCLUSIONS: This preliminary study showed that the Golgi stress response is important in lipotoxic and glucolipotoxic conditions in terms of beta-cell failure. Solving the mystery of intracellular molecular mechanisms leading to beta-cell dysfunction is crucial to understanding the pathophysiology of posttransplant diabetes and most probably the failure of intraportal islet transplants in the long term.

Uncoupling protein gene UCP1-3826A/G, UCP2 Ins/Del and UCP3-55C/T polymorphisms in obese Turkish children.

BACKGROUND: Mitochondrial uncoupling proteins (UCP) 1, 2 and 3 are members of the anion carrier protein family located in the inner mitochondrial membrane. There are various controversial reports on UCP genotypes and obesity in adults and children. This study aims to investigate the link between mostly studied UCP polymorphisms (UCP1-3826A/G, UCP2 Insertion/Deletion (Ins/Del) polymorphism of exon 8, and UCP3-55C/T Polymorphisms) and obesity in Turkish children. Furthermore, the relationships of UCP polymorphisms are also analyzed within the scope of metabolic parameters of obese children. METHODS: Molecular screening of the UCP1, UCP2, and UCP3 gene polymorphisms was carried out in 189 children aged 6 to 18 years, 102 of who had exogenous obesity (54 girls) and 87 of whom were healthy controls (48 girls). In the obese group, fasting lipids, glucose and insulin levels were measured. In 60 obese children, an oral glucose tolerance test (OGTT) was performed with 0, 30, 60, 90 and 120 minutes of sampling for plasma glucose and insulin levels. RESULTS: The frequency of UCP polymorphisms was similar in obese and non-obese children. In obese children, fasting lipids, glucose and insulin levels were not different among the UCP 1, 2 and 3 genotypes. While no relationship was found between the UCP 1 and 3 genotypes and glucose/insulin levels during OGTT, carriers of the Insertion allele with UCP2 Ins/Del polymorphism had significantly higher 30-minute insulin levels (p=0.018). CONCLUSIONS: Polymorphisms of the UCP1-3826A/G, UCP2 Ins/Del, and UCP3-55C/T are not associated with obesity and related pathologies in Turkish children. However, the presence of the Ins allele of the UCP2 gene has been found to have an unfavorable influence on early insulin excursion after glucose loading.

Effect of maternal and neonatal interleukin-6 - 174 G/C polymorphism on preterm birth and neonatal morbidity.

OBJECTIVE: The aim of this study was to analyze maternal and neonatal interleukin 6 (IL-6) (-174 G/C) polymorphism and to determine effect on preterm birth and neonatal morbidity. STUDY DESIGN: One hundred and sixty-four mothers (100 term births, 64 preterm births) and 183 newborn infants who were 100 healthy term and 83 preterm babies followed in newborn intensive care units were evaluated. PCR-RFLP was performed for IL-6 (-174 G/C) genotyping. RESULTS: The rate of GG genotype in mothers of term and preterm infants were 54% (n = 54/100), 75% (n = 48/64), respectively (p > .05) and the rate of GC + CC genotype was 46% (n = 46/100) and 25% (n = 16/64) in mothers giving term and preterm birth (PTB), respectively (p < .05). Additionally, the rate of GG genotype was 65% (n = 65/100) and 81.9% (n = 68/83) in term infants and preterm infants, respectively. GC + CC genotype was 35% (n = 35/100) in term infants and 18.1% (n = 15/83) in preterm infants (p < .05). The effect of IL-6 (-174) GC + CC genotype on PTB was statistically significant. CONCLUSION: The IL-6 174 G/C gene polymorphism was significantly different between mothers who were giving to term and preterm birth. The presence of polymorphism is protective against preterm birth and was not associated with neonatal outcome.

Glial cell-derived neurotrophic factor gene polymorpisms affect severity and functionality of bipolar disorder.

Glial cell-derived neurotrophic factor and other neurotrophins have important role in the development of mental disorders. Here, we aimed to assess the effects of Single nucleotide polymorphisms at potentially regulated regions of GDNF on severity and functionality of bipolar disorder and GDNF serum levels in bipolar disorder patients and healthy volunteers. Severity and functionality of bipolar disorder were evaluated using the Clinical Global Impression and Global Assessment of Functioning scales in sixty-six bipolar disorder patients. The GDNF serum levels obtained from bipolar disorder patients and healthy volunteers who had been already reported SNPs information by our group. GAF scales were lower and GDNF serum levels were higher in Bipolar disorder patients with T/A genotype at 5:37812784 and 5:37812782 compared to patients with T/T genotype. There were significant difference in severity and functionality scores, but not in GDNF serum levels, between patients with G/G and G/A genotype of rs62360370 G > A SNP.rs2075680 C > A and rs79669773 T > C SNPs had no effect on bipolar disorder severity and functionality scores and GDNF serum levels. The results suggest that some SNPs of GDNF have potential association with severity and functionality of bipolar disorder. In addition, except two SNPs, none of GDNF SNPs had association with GDNF serum levels.

Superoxide Dismutase and Catalase Genotypes in Pediatric Migraine Patients.

This study compared superoxide dismutase (SOD) and catalase (CAT) alleles in 97 consecutive children and adolescents with migraine to 96 healthy children and adolescents. Isolated genomic DNA was used as a template for SOD1 (35 A/C), SOD2 16 C/T, and CAT2 [(-262 C/T) and (-21 A/T)] allele genotyping. The SOD2 16 C/T genotype and C allele frequency differed significantly between controls and migraine (P = .047; P = .038). CAT -21 AA genotype and A allele frequency were significantly higher in both migraine with aura patients (P = .013; P = .004) and migraine without aura patients (P = .003; P = .001) compared to controls. To our knowledge, this is the first demonstration of differences in SOD and CAT genotypes between pediatric migraine patients and age-matched controls. Further studies on the functional implications of these genetic variants on neural antioxidant capacity and the use of antioxidant modulators for migraine treatment are warranted.

ß-3AR W64R Polymorphism and 30-Minute Post-Challenge Plasma Glucose Levels in Obese Children.

OBJECTIVE: In this study, we aimed to investigate the association of W64R polymorphism of the ß3-adrenergic receptor gene (ß-3AR) with childhood obesity and related pathologies. METHODS: ß-3AR gene W64R genotyping was carried out in 251 children aged 6-18 years. Of these subjects, 130 were obese (62 boys) and 121 were normal-weight (53 boys). In the obese group, fasting lipids, glucose and insulin levels were measured. Oral glucose tolerance test (OGTT) was performed in 75 of the obese patients. RESULTS: The frequency of W64R genotype was similar in obese and non-obese children. In obese children, relative body mass index, waist-to-hip ratio, serum lipid, glucose and insulin levels, as well as homeostasis model assessment of insulin resistance (HOMA-IR) scores were not different between Arg allele carriers (W64R and R64R) and noncarriers (W64W). In 75 obese children, OGTT results showed that Arg allele carriers had significantly higher 30-minute glucose levels (p=0.027). CONCLUSION: W64R polymorphism of the ß-3AR gene is not associated with obesity and waist-to-hip ratio in Turkish children. Although there were no relationships between the genotypes and lipid, glucose/insulin levels or HOMA-IR, the presence of W64R variant seemed to have an unfavorable influence on early glucose excursion after glucose loading.

TGF-ß1 genotype in pediatric migraine patients.

There is no information about the role of transforming growth factor-beta 1 (TGF-ß1) in the pathogenesis of pediatric migraine. This study included 100 consecutive children and adolescents in whom migraine was diagnosed and 88 healthy children and adolescents. The isolated genomic DNA was used as a template for TGFß-1 (-800G/A, -509C/T, 869T/C [codon 10] and 915G/C [codon 25]) genotyping. The allelic frequency of 509C/T was significantly different between control and migraine without aura patients (P = .04). Codon 10 C/T genotypic and C10 C allelic frequency of TGF-ß1 polymorphisms were significantly higher in migraine and migraine without aura patients versus healthy controls (P = .00; P = .00). To our knowledge, this is the first report dealing with the relationship between TGF-ß1 genotype and migraine in the pediatric age group. Further studies related to this subject are needed, along with a search for new therapeutic agents with anti-inflammatory properties.

Involvement of Toll-like receptors in cervical cancer susceptibility among Tunisian women.

Previous studies underscored the importance of genetic factors in the pathogenesis of certain cancers, including cervical cancer. Epidemiological evidence supports an association between specific polymorphisms of Toll-like receptors (TLR) with several human pathological states, including cervical cancer. The aim of this study was to investigate the link between specific gene variants in TLR2 (-196 to -174 del), TLR3 (c.1377 C>T), TLR4 (Asp299Gly), and TLR9 (2848 G>A) and susceptibility to cervical cancer in Tunisian women. Study subjects comprised 122 women with histopathologically-confirmed cervical cancer, and 260 unrelated age- and ethnically-matched healthy females, who served as controls. TLR genotyping was done using PCR-restriction fragment length polymorphism. The C/C genotype of TLR3 (c.1377 C>T) is associated with cervical cancer susceptibility (OR: 1.71, CI: 1.08-2.70). For TLR4 (Asp299Gly), the Asp/Asp genotype and the Asp allele were associated with higher risk of developing cervical cancer (OR: 4.95, CI: 1.97-13.22) and (OR: 5.17, CI: 2.11-13.50) respectively. We demonstrated no association between the TLR2 (-196 to -174 del) and the TLR 9 (2848 G>A) polymorphisms and the susceptibility of cervical cancer among Tunisian women. However, the C/C genotype for the TLR3 (c.1377 C>T) polymorphism and the Asp/Asp genotype and the Asp allele for (Asp299Gly) TLR4 polymorphism were found to be associated with a higher risk of cervical cancer.

Alterations in BDNF (brain derived neurotrophic factor) and GDNF (glial cell line-derived neurotrophic factor) serum levels in bipolar disorder: The role of lithium.

OBJECTIVE: Brain-derived neurotrophic factor (BDNF) has been consistently reported to be decreased in mania or depression in bipolar disorders. Evidence suggests that Glial cell line-derived neurotrophic factor (GDNF) has a role in the pathogenesis of mood disorders. Whether GDNF and BDNF act in the same way across different episodes in bipolar disorders is unclear. METHOD: BDNF and GDNF serum levels were measured simultaneously by enzyme-linked immunosorbent assay (ELISA) method in 96 patients diagnosed with bipolar disorder according to DSM-IV (37 euthymic, 33 manic, 26 depressed) in comparison to 61 healthy volunteers. SCID- I and SCID-non patient version were used for clinical evaluation of the patients and healthy volunteers respectively. Correlations between the two trophic factor levels, and medication dose, duration and serum levels of lithium or valproate were studied across different episodes of illness. RESULTS: Patients had significantly lower BDNF levels during mania and depression compared to euthymic patients and healthy controls. GDNF levels were not distinctive. However GDNF/BDNF ratio was higher in manic state compared to euthymia and healthy controls. Significant negative correlation was observed between BDNF and GDNF levels in euthymic patients. While BDNF levels correlated positively, GDNF levels correlated negatively with lithium levels. Regression analysis confirmed that lithium levels predicted only GDNF levels positively in mania, and negatively in euthymia. LIMITATIONS: Small sample size in different episodes and drug-free patients was the limitation of thestudy. CONCLUSION: Current data suggests that lithium exerts its therapeutic action by an inverse effect on BDNF and GDNF levels, possibly by up-regulating BDNF and down-regulating GDNF to achieve euthymia.