Gurler Akpinar

Methylenetetrahydrofolate reductase gene polymorphisms are associated with ischemic and hemorrhagic stroke: Dual effect of MTHFR polymorphisms C677T and A1298C.

Hyperhomocysteinemia is an independent risk factor for ischemic stroke. The enzyme methylenetetrahydrofolate reductase (MTHFR) plays a critical role in modulating the levels of plasma homocysteine. Two polymorphisms in the MTHFR gene, C677T, A1298C result in reduced enzyme activity. The mechanisms of ischemic and hemorrhagic stroke are not well understood. Although controversial, previous studies have shown evidence of causality of both stroke subtypes in patients with methylenetetrahydrofolate reductase gene polymorphisms. Therefore, we examined whether the C677T and A1298C polymorphisms of MTHFR gene are genetic risk factors for both ischemic and hemorrhagic stroke in a Turkish Caucasian population. In a case-control study, 120 total unrelated stroke patients (92 ischemic stroke, 28 hemorrhagic stroke), and 259 healthy controls were genotyped for C677T and A1298C polymorphisms of the MTHFR gene using a PCR-RFLP based-method. The MTHFR 1298C allele (chi(2)=8.589; P=0.014), C1298C genotype (OR=2.544; P=0.004), and C677C/C1298C compound genotype (OR=3.020; P=0.001) were associated with overall stroke. The MTHFR 1298C allele (chi(2)=11.166; P=0.004), C1298C genotype (OR=2.950; P=0.001), and C677C/C1298C compound genotype (OR=3.463, P=0.0001) were strongly associated with ischemic stroke. Interestingly however, the MTHFR 677T allele (chi(2)=6.033; P=0.049), T677T genotype (OR=3.120; P=0.014), and T677T/A1298A compound genotype (OR=4.211; P=0.002) were associated with hemorrhagic stroke. In conclusion, the C677T and A1298C polymorphisms of the MTHFR gene are genetic risk factors for hamorrhagic and ischemic stroke respectively, independent of other atherothrombotic risk factors.

Association of apolipoprotein E polymorphisms in patients with non-alcoholic steatohepatitis.

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of abnormal hepatic steatosis in the absence of alcohol abuse worldwide. Non-alcoholic steatohepatitis (NASH) is the most progressive form of NAFLD. The aim of this study was to investigate the role of apolipoprotein E (APOE) polymorphisms in the development of NASH. We analysed 57 NASH patients and 245 healthy controls using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method in a case–control study. The diagnosis of the patients was based on liver biopsy. The serum levels of glucose, lipids, vitamin B12, folic acid, homocysteine, insulin, total biluribin, total protein, albumin, ferritin, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were determined in all of the subjects. Body mass index (BMI), waist circumference (WC), AST, ALT, fasting blood sugar (FBS), total cholesterol, triglyceride (TG), low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein (VLDL) cholesterol, insulin and ferritin levels were significantly higher in the 57 patients with NASH compared with the 245 healthy controls. The APOE ε3 allele was overrepresented in the whole group of NASH patients (ε3=97.37% in NASH versus 82.45% in controls). The APOE polymorphism was statistically significantly associated with NASH (χ2=15.741; p=0.008). The APOE3/3 genotype (odds ratio [OR]=7.941; p=0.000) was strongly associated with increased risk for NASH in all NASH patients. Consequently, the APOE3/3 genotype may play a role in the aetiopathogenesis of NASH.

Phenotypic and Proteomic Characteristics of Human Dental Pulp Derived Mesenchymal Stem Cells from a Natal, an Exfoliated Deciduous, and an Impacted Third Molar Tooth

The level of heterogeneity among the isolated stem cells makes them less valuable for clinical use. The purpose of this study was to understand the level of heterogeneity among human dental pulp derived mesenchymal stem cells by using basic cell biology and proteomic approaches. The cells were isolated from a natal (NDPSCs), an exfoliated deciduous (stem cells from human exfoliated deciduous (SHED)), and an impacted third molar (DPSCs) tooth of three different donors. All three stem cells displayed similar features related to morphology, proliferation rates, expression of various cell surface markers, and differentiation potentials into adipocytes, osteocytes, and chondrocytes. Furthermore, using 2DE approach coupled with MALDI-TOF/TOF, we have generated a common 2DE profile for all three stem cells. We found that 62.3 ± 7% of the protein spots were conserved among the three mesenchymal stem cell lines. Sixty-one of these conserved spots were identified by MALDI-TOF/TOF analysis. Classification of the identified proteins based on biological function revealed that structurally important proteins and proteins that are involved in protein folding machinery are predominantly expressed by all three stem cell lines. Some of these proteins may hold importance in understanding specific properties of human dental pulp derived mesenchymal stem cells.

Evidence for the presence of full-length PARK2 mRNA and Parkin protein in human blood

Research on Parkinsons disease fails to pinpoint a single gene or a gene product as the causative factor. However, the early onset form of the disease may be caused by mutations in PARK2 gene. Some studies related to the biochemistry or other aspects of the PARK2 gene or its product mostly used cDNA generated from substantia nigra of the mid-brain. This is essentially because the presence of the 1.4kb full-length PARK2 cDNA in human leukocytes is, so far, not demonstrated although some splice variants and short RT-PCR products were reported. In this study, we synthesized a 1.4kb full-length PARK2 cDNA from human leukocytes, cloned and expressed it both in Escherichia coli and in HeLa cells. The presence of Parkin protein was also demonstrated in human serum using Western blotting and MALDI-TOF analysis. The results of this study showed a simple way for routine amplification of PARK2 cDNA from human blood and may become a useful diagnostic tool in the future.

Neonatal hyperbilirubinemia and organic anion transporting polypeptide-2 gene mutations.

The aim of this study was to investigate the genotypic distribution of organic anion transporting polypeptide 2 (OATP-2) gene mutations and the relationship with hyperbilirubinemia of unknown etiology. Polymerase chain reaction, restriction fragment length polymorphism, and agarose gel electrophoresis techniques were used for detection of OATP-2 gene mutations in 155 newborn infants: 37 with unexplained hyperbilirubinemia, 65 with explained hyperbilirubinemia, and 53 without hyperbilirubinemia. In the OATP-2 gene, we identified A→G transitions at nucleotide positions 388 and 411 and observed six polymorphic forms. The 388/411-411 mutation was the most common form (43%) in subjects with hyperbilirubinemia of unknown etiology. Male sex [odds ratio (OR): 3.08] and two polymorphic forms of the OATP-2 gene [the 388/411-411 A→G mutation (OR: 3.6) and the 388-411 mutation (OR: 2.4)] increased the risk of neonatal hyperbilirubinemia. In male infants with the 388 A→G mutation of the OATP-2 gene, the levels of unconjugated bilirubin in plasma were significantly increased compared with those observed in females. The polymorphic forms of 388 nucleotide of the OATP-2 gene were identified as risk factors for hyperbilirubinemia of unknown etiology.

The prominent proteins expressed in healthy gingiva: a pilot exploratory tissue proteomics study

Gingiva is a unique tissue which protects the underlying periodontal tissues from consistent mechanical and bacterial aggressions. Molecular analysis of gingiva is likely to improve our understanding of the underlying biological processes at work. The aim of this preliminary exploratory study is to analyze the proteomic profile of healthy gingiva and to detect prominently expressed proteins. Gingival tissue samples were obtained from periodontally healthy individuals who underwent surgical crown lengthening procedure. After protein isolation, two dimensional gel electrophoresis (2DE) gels were prepared for each sample and only protein spots common to all gels were selected to eliminate the bias caused by the effect of individuals on proteomic profile. Following the 2DE; in-gel tryptic digestion and MALDI-TOF/TOF steps were performed for protein identifications. Forty-seven proteins were successfully identified. The identified proteins were classified based on their classes, molecular functions and involvements in biological processes and metabolic pathways. Among them, 14-3-3 protein sigma, Protein DJ-1, Alpha-enolase, Triosephosphate isomerase, Superoxide dismutase, Peroxiredoxin-1, Protein S100-A9, Galectin-7, Annexin A2/A4, Carbonic anhydrase 1 and chaperone proteins are worthy of attention. The proteomic profile of the gingiva reflected its highly dynamic characteristics. Despite complexity of the gingival tissue proteome, 2DE was an effective approach in studying the common protein expression profile of the gingiva. Considering the significance of gingiva in the formation of periodontal diseases, it is important to generate a detailed proteome map of gingival tissue to set up a bridge between molecular events and the disease formation. This study established an initial proteome map of the gingival tissue from healthy individuals.

Linking a compound-heterozygous Parkin mutant (Q311R and A371T) to Parkinson's disease by using proteomic and molecular approaches

Parkin is an E3-protein ubiquitin ligase, which plays an important role as a scavenger in cell metabolism. Since the discovery of the link between Parkin and Parkinsons disease, Parkin was placed in the center of Parkinsons disease research. Previously, we isolated a mutant form of the Parkin protein (Q311R and A371T) from a Parkinsons disease patient. In this study, we aimed at characterizing this mutant Parkin protein by using biochemical and proteomic approaches. We used neuroblastoma cells (SH-SY5Y) as our model and created two inducible cell lines that expressed the wild type and the mutant Parkin proteins. We first investigated the effect of expressing both the wild type and the mutant Parkin proteins on the overall proteome by using 2D-DIGE approach. The experiments yielded the identification of 22 differentially regulated proteins, of which 13 were regulated in the mutant Parkin expressing cells. Classification of the identified proteins based on biological process and molecular function revealed that the majority of the regulated proteins belonged to protein folding and energy metabolism. Ingenuity Pathway Analysis predicted the presence of a link between the regulated proteins of the mutant Parkin expressing cells and Parkinsons disease. We also performed biochemical characterization studies on the wild type and the mutant Parkin proteins to make sense out of the differences observed at the proteome level. Both proteins displayed biological activity, had similar stabilities and localized similarly to the cytoplasm and the nucleus in SH-SY5Y cells. The mutant protein, however, was cut by a protease and subjected to a post-translational modification. The observed differences at the proteome level might be due to the differences in processing of the mutant Parkin protein. Overall, we were able to create a possible link between a pair of Parkin mutations to its pertinent disease by using 2D-DIGE in combination with biochemical and molecular approaches.

A unique Golgi apparatus distribution may be a marker for osteogenic differentiation of hDP-MSCs

Stem cell markers are utilized to isolate or identify stem cells. So far, many stem‐cell‐specific markers have been described, although some of them turned out to be not as specific as it was originally proposed. In this study, we sought to search for a specific stem cell marker that would be phenotypically helpful, characteristically specific, economically affordable and easy to use. Because organelles are one of the major characteristics of eukaryotic cells, we asked the question of whether organelle characteristics might be a useful tool for stem cell characterization. We studied distribution and characteristics of the endoplasmic reticulum, the mitochondria and the Golgi apparatus in human dental‐pulp‐derived mesenchymal stem cells before and during osteogenic differentiation. Although it was not possible to find a useful macromolecular marker for stem cell characterization, we found that during osteogenic differentiation, the stem cells changed their Golgi characteristics and displayed a unique in vivo pattern. We analysed these unique Golgi structures and proposed a potential osteogenic differentiation marker for human dental‐pulp‐derived mesenchymal stem cells. This pattern may be used in the evaluation of osteogenic differentiation. Copyright

Comparative Proteome Analysis of hAT-MSCs Isolated from Chronic Renal Failure Patients with Differences in Their Bone Turnover Status.

The relationship between the stem cells and the bone turnover in uremic bone disease due to chronic renal failure (CRF) is not described. The aim of this study was to investigate the effect of bone turnover status on stem cell properties. To search for the presence of such link and shed some light on stem-cell relevant mechanisms of bone turnover, we carried out a study with mesenchymal stem cells. Tissue biopsies were taken from the abdominal subcutaneous adipose tissue of a CRF patient with secondary hyperparathyroidism with the high turnover bone disease. This patient underwent parathyroidectomy operation (PTX) and another sample was taken from this patient after PTX. A CRF patient with adynamic bone disease with low turnover and a healthy control were also included. Mesenchymal stem cells isolated from the subjects were analyzed using proteomic and molecular approaches. Except ALP activity, the bone turnover status did not affect common stem cell properties. However, detailed proteome analysis revealed the presence of regulated protein spots. A total of 32 protein spots were identified following 2D gel electrophoresis and MALDI-TOF/TOF analyzes. The identified proteins were classified into seven distinct groups and their potential relationship to bone turnover were discussed. Distinct protein expression patterns emerged in relation to the bone turnover status indicate a possible link between the stem cells and bone turnover in uremic bone disease due to CRF.

Al2O3 micro- and nanostructures affect vascular cell response

In-stent restenosis (ISR) is one of the most common and serious complications observed after stent implantation. ISR is characterized by the inordinate proliferation of smooth muscle cells (SMC) that leads to narrowing of the blood vessels. To achieve a healthy endothelium, it is critical to selectively enhance the growth of endothelial cells (EC) while suppressing the growth of smooth muscle cells, which is still a major challenge and yet to be achieved. In this study, novel surfaces have been developed to support the selective growth of endothelial cells. Micro- and nanostructured Al2O3 surfaces with unique topographical features were fabricated and tested. Surface characterization and cellular response of endothelial cells (HUVEC) as well as smooth muscle cells (HUVSMC) has been investigated at cellular and molecular levels. A topography driven selective cell response of ECs over SMCs was demonstrated successfully. This selective response of ECs was also analyzed at protein levels in order to understand the basic mechanism.