Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Subject: search.filters.subject.Neuraminidase

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Now showing 1 - 5 of 5
  • Master Thesis
    Investigation of the Biological Role of Mouse Acylneuraminyl Hydrolase Enzymes in the Regulation of Neuroinflammation
    (Izmir Institute of Technology, 2022) Tabakacılar, Doğa; Seyrantepe, Volkan
    Sialidosis is a lysosomal storage disorder, and it is inherited by autosomal recessive mutations in the Neuraminidase 1 (NEU1) gene. Neuraminidases or sialidases are catalytic enzymes that carry out the desialylation of glycoconjugates. Deficiencies of neuraminidases lead to the accumulation of sialoglycoconjugates in membranes of cells. Neuroinflammation and neurodegeneration are present in some lysosomal storage diseases such as Tay-Sachs. However, in the sialidosis mouse model, neuroinflammation was never studied. In this study, we investigated the effect of neuraminidase 1, neuraminidase 3, and their combined deficiency on neuroinflammation by using Neu1-/-, Neu3-/- knockout, and Neu1-/- Neu3-/- double knockout mouse models. Neu1-/- Neu3-/- knockout mouse model was smaller in comparison to its littermates and showed muscle weakness, tremoring, and 2-3 weeks of a lifetime. Some of the Neu1-/- Neu3-/- mice died prematurely. To unravel the pathology immunohistochemical, biological, and chromatographic techniques were used. The expression of inflammatory cytokines was altered in the Neu1-/-, Neu3-/-, and Neu1-/- Neu3-/- mice with respect to the brain section. Neu1-/- Neu3-/- mice showed generally the highest expression of cytokines in the cerebellum compared to the cortex. Neuronal loss was observed in the Neu1-/- Neu3-/- mice in the cortex, thalamus, and cerebellum. The most remarkable change was in the ganglioside expression pattern in the Neu1-/- Neu3-/- mice cortex. GD3 expression was present in the cortex of Neu1-/- Neu3-/- mice where expression of this ganglioside is related to neuroinflammation, neurodegenerative stimuli, autophagosome remodeling and programmed cell death.
  • Master Thesis
    Investigating the Biological Role of Sialidase Neu4 and Gm3 Synthase Enzymes in a Mouse Model of Tay-Sachs Disease
    (Izmir Institute of Technology, 2017) Barnar, Talha; Seyrantepe, Volkan
    β-Hexaminidase A which has role in GM2 degradation in glycosphingolipid pathway is known to be main enzyme for Tay-Sachs disease. Although recessive mutant phenotype of this enzyme causes disease in human, Hexa gene knockout mice show less accumulation of GM2 ganglioside than human. To avoid excess GM2 accumulation, mice uses neuraminidases convert GM2 into GA2. In addition, among neuraminidases, it has been found that Neu4-/-Hexa-/- mice can be good model for Tay-Sachs diseases (Seyrantepe et al., 2010). On the other hand, to prevent GM2 accumulation, blocking GM3 synthase is the finest method because GM3 synthase plays a big part in ganglioside synthesis pathway by producing GM3 that is later converted into GM2 or GD3 ganglioside. In addition, GM3 synthase deficient mice can live longer than 1 year. In this study, Hexa-/-GM3S-/-Neu4-/- mice with single and double variants were produced and brain regions were analyzed with thin-layer chromatography, immunohistochemistry, and real-time PCR methods. This investigation was conducted to clarify real function of GM3S on Tay-Sachs mice model and to search for possible effects of Neu4 in ganglioside pathway. Although GM2 accumulation are present in Hexa-/- and Neu4-/-Hexa-/-mice, analysis of Hexa-/-GM3S-/-Neu4-/-and Hexa-/-GM3S-/- mice revealed that there is no GM2 accumulation without GM3 synthase enzyme. These results are consistent with known ganglioside synthesis pathway. Hexa-/-GM3S-/-Neu4-/- and double deficient Neu4-/-mice variants disclosed change of Neu3 and Neu2 concentration to the wild type mice. In regard of these results, change in other neuraminidase expression is to compensate Neu4 function.
  • Master Thesis
    Identification of Cytosolic Sialidase Neu2 Associated Proteins Bt Mass Spectrometric Analysis
    (Izmir Institute of Technology, 2013) Akyıldız Demir, Seçil; Seyrantepe, Volkan
    Sialidases (Neuraminidases) are the enzymes which remove sialic acids from glycoproteins, oligosacharides and glycolipids. Four mammalian sialidases have been identified which are lysosomal sialidase (Neu1), cytosolic sialidase (Neu2), plasma membrane sialidase (Neu3), and mitochondrial/lysosomal sialidase (Neu4). These enzymes differ in their subcellular localizations, expression levels in different cells and tissues, substrate specificities and optimum pH levels. Cytosolic Neu2 enzyme has an active role on a wide range of subtances including oligosaccharides, glycopeptides and gangliosides. Studies on the Neu2 enzyme also showed that this enzyme is involved in different cellular events including cancer metabolism, neuronal differentiation and myoblast differentiation, proliferation and hypertrophy. However, it has not been shown whether Neu2 interacts with other proteins within the cell. Therefore, in this study we aimed to identify Neu2 associated proteins by using InterPlay Mammalian TAP System and ESI-LC-MS/MS analysis. Proteins in the Neu2 protein complex were identified by three different database search software such as PGLS, Mascot and X!Tandem. As a result of experiment Actin proteins (Alpha Actin, Gamma Actin and Beta Actin), and Calsyntenin-2 protein were found as a candidate protein for Neu2 association. The interaction between Neu2 and β-Actin proteins was confirmed by western blot analysis.
  • Master Thesis
    Analysis of Lysosomal Neu4 Sialidase Associated Proteins by Using Mass Spectrometry (ms/Ms)
    (Izmir Institute of Technology, 2012) Öztürk, Süleyman Can; Seyrantepe, Volkan; Seyrantepe, Volkan
    Sialidases are glycohydrolytic enzymes which remove sialic acid residues from glycoproteins, oligosaccharides and glycolipids. There are 4 different sialidases known in mammalians. These are Neu1 (lysosomal), Neu2 (cytoplasmic), Neu3 (cell membrane) and Neu4 (lysosomal/mitochondrial) sialidase. Sialidases are involved in many metabolic and cellular processes interactioning with another proteins or work together in multiprotein complexes. For example, Neu1 is only active with betagalactosidase and cathepsin A enzyme in lysosome. Interactions of sialidases Neu2, Neu3 and Neu4 enzyme with other proteins remain unknown In our study, we aimed to identify proteins which have interaction with sialidase Neu4 as well as Neu1 by using mass spectrometry analysis to find new possible roles of sialidases. Our bait protein's cDNA was tagged with calmodulin binding protein as well as streptavidin binding protein. After transfection and expression of vectors to mammalian cells, proteins were purified using tandem affinity purification (TAP). We identified some associated proteins with sialidase Neu1 and Neu4 by using MS/MS analysis and bioinformatics.
  • Master Thesis
    Molecular Analysis of Mammalian Neu4 Sialidase Gene Promoter
    (Izmir Institute of Technology, 2011) Delman, Murat; Seyrantepe, Volkan
    There are four different mammalian sialidases that have been described; lysosomal (Neu1), cytoplasmic (Neu2), plasma membrane (Neu3), lysosomal/mitochondrial (Neu4). The activity of sialidase Neu4 enzyme against sialic acid containing ganglioside GM2 has been demonstrated. Biological role of sialidase Neu4 enzyme has been shown by the transfection of neuroglia cells from a Tay-Sachs patient with a Neu4-expressing plasmid showed clearance of accumulated ganglioside GM2. It has been also shown that sialidase Neu4 enzyme is responsible for degradation reactions of another ganglioside such as GD1a in brains of Neu4-/- mice. Aim of our study is to identify minimal promoter region of human Neu4 gene and demonstrate binding of transcription factors to this region. In our study, we used bioinformatic approaches to predict the sequence motifs where several specific transcription factors bind using TESS (Transcription Element Seach System) tool. We amplified seven different DNA fragments from human Neu4 promoter region, cloned into luciferase expression vector and performed reporter assay. We also performed electrophoretic mobility shift assay to demonstrate binding of transcription factors to candidate promoter region. We demonstrated that 187 bp upstream of Neu4 gene is minimal promoter region to control transcription from Neu4 gene. Electrophoretic mobility shift assay showed that 187 bp upstream region recruits several transcription factors. Our results demonstrated the minimal promoter region revealing several putative transcription factors such as Sp-1 and c-myc which might be responsible mainly for regulation of Neu4 gene transcription. The data we obtained might be useful to discover small molecules which can control Neu4 gene expression. High expression of Neu4 gene might be controlled using drugs or small molecules and the accumulated GM2 ganglioside in lysosomes of Tay-Sachs patients can be reduced.