Master Degree / Yüksek Lisans Tezleri

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

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COAR Access Rights: search.filters.coarAccessRights.open accessSubject: search.filters.subject.Gap junctions (Cell biology)

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  • Master Thesis
    Investigating the Function of Cx26-I30n and D50y Mutations in Squamous Cell Carcinoma Cell Line Scc-25
    (01. Izmir Institute of Technology, 2021) Yavuz, Büşra; Meşe Özçivici, Gülistan
    Gap junctions are responsible for cell homeostasis and provide cell-cell and cell-ECM communications in multicellular organisms. Gap junction hemichannels consist of connexin (Cx) proteins which functions are crucial for human physiology. Moreover, Cx mutations are associated with various genetic diseases. For example, more than 10 missense mutations in the Cx26 gene cause keratitis-ichthyosis-deafness (KID) syndrome. Among these, Cx26-I30N and Cx26-D50Y cause to form abnormal hemichannels and allow excessive calcium influx into the cell. Furthermore, KID patients have higher squamous cell carcinoma (SCC) incidence and SCC is seen at an earlier age in these patients. Immunohistochemistry stainings have demonstrated aberrant E-cadherin and B-catenin spread in KID patients' samples. In this study, we aimed to effects of Cx26-I30N and Cx26-D50Y mutations associated with KID syndrome in human epithelial SCC cell line SCC-25. For this purpose, stable MSCV, Cx26-WT, Cx26-I30N and Cx26-D50Y cell lines were generated and RTqPCR, Western blotting, immunostaining and MTT assays were done for expression level, localization and viability analysis. For these 4 different cell conditions, a significant increase was detected at Cx26 mRNA levels, but not at protein levels. No difference was found in Cx43 level, which is abundant in epithelial tissue, and was localized in the perinuclear area like Cx26. Additionally, E-cadherin protein levels increased and their localization changed in parallel with the mutations from the perinuclear area to the plasma membrane. Moreover, significant decreases in viability were observed in cells grown in high extracellular Ca2+ medium compared to control in contrast to cells grown in Ca2+-free medium.
  • Master Thesis
    Deciphering Functions of Aberrant Hemichannels Formed by Connexin 26- I30n and D50y Mutations
    (Izmir Institute of Technology, 2015) Aypek, Hande; Meşe Özçivici, Gülistan
    Cells need to communicate with each other for maintenance cellular and tissue homeostasis. Gap junctions are channel-forming structures that are formed by docking of two hemichannels on the plasma membrane of adjacent cells. Connexins are subunits of gap junctions. Connexin 26 (Cx26) is one of the connexin isoform and mutations on the Cx26 gene (GJB2) cause non-syndromic and syndromic deafness. Keratitis-ichthyosis-deafness (KID) syndrome is one of the syndromic deafness disorders caused by Cx26 mutations. Among these mutations, Cx26-I30N and D50Y missense mutations were shown to form aberrant hemichannels but their effect on protein biosynthesis and functions have not studied. In this study, we aimed to decipher in vitro functions of aberrant hemichannels formed by Cx26-I30N and D50Y mutations. First of all, the effect of Cx26-I30N and D50Y mutations on localization, mRNA expression and protein synthesis properties were investigated in HeLa, N2A and HaCaT cells. Results suggested that Cx26-I30N and D50Y mutants were not able to form gap junction plaques on the plasma membrane and were localized in the Golgi apparatus. In addition, mutations resulted in a reduction in mRNA expression and protein synthesis. After, functional analysis was performed in Cx26-I30N and D50Y transfected N2A and HaCaT cells. Internal Ca2+ content measurement, measurement of released ATP, measurement of cell size and apoptosis assays were performed. Ca2+ measurement results showed that both Cx26-I30N and D50Y mutations deregulate Ca2+ balance in both N2A and HaCaT cells. Result of ATP release assay indicated that ATP amount in the extracellular environment decreased in N2A cells having Cx26-I30N and D50Y clones. Finally, apoptosis assay showed that number of necrotic cells increased when N2A cells were transfected with Cx26-I30N and D50Y constructs. Therefore, it was shown that aberrant hemichannels formed by Cx26-I30N and D50Y mutations may induce necrotic cell death by disrupting Ca2+ balance and ATP amount in cells.