Molecular Biology and Genetics / Moleküler Biyoloji ve Genetik

Permanent URI for this collectionhttps://hdl.handle.net/11147/9

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Institution Author: search.filters.institutionAuthor.Demir, Seçil AkyıldızLanguage: search.filters.language.en

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Now showing 1 - 5 of 5
  • Article
    Citation - WoS: 37
    Citation - Scopus: 40
    Gm2 Ganglioside Accumulation Causes Neuroinflammation and Behavioral Alterations in a Mouse Model of Early Onset Tay-Sachs Disease
    (BioMed Central Ltd., 2020) Akyıldız Demir, Seçil; Timur, Zehra Kevser; Ateş, Nurselin; Martinez, Luis Alarcon; Seyrantepe, Volkan
    Background Tay-Sachs disease (TSD), a type of GM2-gangliosidosis, is a progressive neurodegenerative lysosomal storage disorder caused by mutations in the alpha subunit of the lysosomal beta-hexosaminidase enzyme. This disease is characterized by excessive accumulation of GM2 ganglioside, predominantly in the central nervous system. Although Tay-Sachs patients appear normal at birth, the progressive accumulation of undegraded GM2 gangliosides in neurons leads to death. Recently, an early onset Tay-Sachs disease mouse model, with genotypeHexa-/-Neu3-/-, was generated. Progressive accumulation of GM2 led to premature death of the double KO mice. Importantly, this double-deficient mouse model displays typical features of Tay-Sachs patients, such as cytoplasmic vacuolization of nerve cells, deterioration of Purkinje cells, neuronal death, deceleration in movement, ataxia, and tremors. GM2-gangliosidosis is characterized by acute neurodegeneration preceded by activated microglia expansion, macrophage, and astrocyte activation, along with the production of inflammatory mediators. However, the mechanism of disease progression inHexa-/-Neu3-/-mice, relevant to neuroinflammation is poorly understood. Method In this study, we investigated the onset and progression of neuroinflammatory changes in the cortex, cerebellum, and retina ofHexa-/-Neu3-/-mice and control littermates by using a combination of molecular genetics and immunochemical procedures. Results We found elevated levels of pro-inflammatory cytokine and chemokine transcripts, such as Ccl2, Ccl3, Ccl4, and Cxcl10 and also extensive microglial and astrocyte activation and proliferation, accompanied by peripheral blood mononuclear cell infiltration in the vicinity of neurons and oligodendrocytes. Behavioral tests demonstrated a high level of anxiety, and age-dependent loss in both spatial learning and fear memory inHexa-/-Neu3-/-mice compared with that in the controls. Conclusion Altogether, our data suggest thatHexa-/-Neu3-/-mice display a phenotype similar to Tay-Sachs patients suffering from chronic neuroinflammation triggered by GM2 accumulation. Furthermore, our work contributes to better understanding of the neuropathology in a mouse model of early onset Tay-Sachs disease.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Identification of Cytoplasmic Sialidase Neu2-Associated Proteins by Lc-ms/Ms
    (Türk Biyokimya Derneği, 2019) Akyıldız Demir, Seçil; Seyrantepe, Volkan
    Background: Cytoplasmic sialidase (NEU2) plays an active role in removing sialic acids from oligosaccharides, gly-copeptides, and gangliosides in mammalian cells. NEU2 is involved in various cellular events, including cancer metabolism, neuronal and myoblast differentiation, proliferation, and hypertrophy. However, NEU2-interacting protein(s) within the cell have not been identified yet. Objective: The aim of this study is to investigate NEU2 interacting proteins using two-step affinity purification (TAP) strategy combined with mass spectrometry analysis. Methods: In this study, NEU2 gene was cloned into the pCTAP expression vector and transiently transfected to COS-7 cells by using PEI. The most efficient expression time of NEU2- tag protein was determined by real-time PCR and Western blot analysis. NEU2-interacting protein(s) were investigated by using TAP strategy combined with two different mass spectrometry experiment; LC-MS/MS and MALDI TOF/TOF. Results: Here, mass spectrometry analysis showed four proteins; a-actin, beta-actin, calmodulin and histone H1.2 proteins are associated with NEU2. The interactions between NEU2 and actin filaments were verified by Western blot analysis and immunofluorescence analysis. Conclusions: Our study suggests that association of NEU2 with actin filaments and other protein(s) could be important for understanding the biological role of NEU2 in mammalian cells.
  • Conference Object
    Abnormal Gm2 Accumulation Alters the Function of the Autophagic Pathway in Early-Onset Tay-Sachs Disease Mouse Model
    (Academic Press, 2018) Seyrantepe, Volkan; Ateş, Nurselin; Can, Melike; Şengül, Tuğçe; Akyıldız Demir, Seçil
    Tay-Sachs disease (TSD) is an inborn error of metabolism, a prototypical lysosomal disease of the nervous system. In humans, the fatal infantile acute form is the most common, and with no current treatment, prevention and palliative care the only options. TSD mice did not mimic human infantile TSD, and although mice showed some early pathology and storage of GM2 ganglioside, clinical disease would take many months to develop. The extremely mild disease in the TSD mice was likely due to a biochemical bypass, a neuraminidase. We recently demostrated that at least one of the principal murine neuraminidase, Neu3, responsible for the biochemical bypass in the catabolism of the GM2 ganglioside.
  • Conference Object
    Alteration in Redox Homeostasis in Early-Onset Tay-Sachs Disease Mouse Model
    (Academic Press, 2020) Seyrantepe, Volkan; Ateş, Nurselin; Başırlı, Hatice Hande; Demir, Seçil Akyıldız; Dağalp, Berkay; Nalbant, Ayten; Çalışkan, Tufan Utku
    Tay-Sachs disease is an autosomal recessively inherited lysosomal disorder. It is caused by mutations on the HEXA gene encoding α-subunit of β-Hexosaminidase A enzyme. The enzyme normally catalyzes GM2 to GM3 conversion but when it is absent or dysfunctional the GM2 degradation is interrupted. The undegraded GM2 ganglioside is progressively accumulated especially in neurons and causes neurodegenaration at the end. The Hexa−/− mice generated as Tay-Sachs model was nearly normal and a bypass mechanism mediated by a sialidase was suggested. Recently we determined that Neu3 sialidase involves in ganglioside degradation in the Tay-Sachs disease pathology and the Hexa−/-Neu3−/− mice mimic the neuropathologic and clinical phenotype of the disease. It was reported that oxidative stress is triggered in neurodegenerative diseases and several lysosomal disorders. It is caused by the imbalance between antioxidant defence mechanism and production of reactive oxygen species (ROS). ROS have high chemical reactivity which react and damage DNA, protein, carbohydrates and lipids.
  • Article
    Citation - WoS: 28
    Citation - Scopus: 31
    Lysosomal Cathepsin a Plays a Significant Role in the Processing of Endogenous Bioactive Peptides
    (Frontiers Media S.A., 2016) Timur, Zehra Kevser; Akyıldız Demir, Seçil; Seyrantepe, Volkan
    Lysosomal serine carboxypeptidase Cathepsin A (CTSA) is a multifunctional enzyme with distinct protective and catalytic function. CTSA present in the lysosomal multienzyme complex to facilitate the correct lysosomal routing, stability and activation of with beta-galactosidase and alpha-neuraminidase. Beside CTSA has role in inactivation of bioactive peptides including bradykinin, substances P, oxytocin, angiotensin I and endothelin-I by cleavage of 1 or 2 amino acid(s) from C-terminal ends. In this study, we aimed to elucidate the regulatory role of CTSA on bioactive peptides in knock-in mice model of CTSA(S190A). We investigated the level of bradykinin, substances P, oxytocin, angiotensin I and endothelin-I in the kidney, liver, lung, brain and serum from CTSA(S190A) mouse model at 3- and 6-months of age. Our results suggest CTSA selectively contributes to processing of bioactive peptides in different tissues from CTSA(S190A) mice compared to age matched WT mice.