Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Hatab, A.
Function and Expression of Cancer Mutations of the KCNJ3 Gene
Humanmedizin; [ Diplomarbeit ] Medizinische Universität Graz; 2023. pp. 59
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Gorischek Astrid
- Schreibmayer Wolfgang
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- Abstract:
- Introduction: Searching the Genomic Data Commons (GDC) Data Portal of the National Cancer Institute (NCI) revealed 305 cancer cases out of 13,714 cases of primary malignant tumors that contained 321 somatic mutations of the KCNJ3 gene. The uterine, skin, and lung tumors with KCNJ3 somatic mutations were the most common sites for these mutations https://portal.gdc.cancer. We concentrated on 15 missense mutations in a section that comprises the ion selectivity fingerprint and the P-helix, which are essential for ion selectivity. This region is located between the first and second transmembrane helix (Nishida, Cadene et al. 2007). Aim, material and methods: The focus of this diploma thesis is to investigate potential effects of KCNJ3 mutations on (a) protein expression, (b) ion channel gating, (c) ion selectivity, and (d) subunit assembly of GIRK channels. Electrophysiological characterization of GIRK channels expressed in Xenopus laevis oocytes, both wild-type and mutant, was achieved by using the Two Electrode Voltage clamp (TEVC). The level of expressed protein was evaluated utilizing confocal laser scan microscopy (cLSM). Results: The mutations investigated in this thesis showed phenotypes that could be classified into three main groups: (i) normal/reduced expression along with decreased/absent function (S132Y, F136L, E139K, G145A, R149Q, R149P, G178D, S185Y, Q186R) (ii) normal/increased expression along with increased function (E140M, A142T, M184I) and (iii) low expression however increased function (I151N, G158S). Discussion: It has been observed that none of the analyzed mutations can result in functioning homomeric ion channels, and any trace amounts of currents that were seen have been caused by a lack of antisense oligonucleotide silencing of the endogenous GIRK5 subunit. We propose that groups (ii) and (iii) may have a role in the development and progression of malignancies, especially in tissues where somatic KCNJ3 mutations arise frequently. Further studies on human cancer, cancer proliferation, and differentiation will be necessary to determine if somatic mutations in the KCNJ3 gene might indeed be important in clinical applications.