Molecular Biology and Genetics / Moleküler Biyoloji ve Genetik
Permanent URI for this collectionhttps://hdl.handle.net/11147/9
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Conference Object Investigation of the role of Wnt/β-catenin signaling in development of Alzheimer's disease in a zebrafish model of mmyloid-β toxicity(Wiley, 2024) Nazlı, Dilek; Ipekgil, D.; Poyraz, Y. K.; Catak, B.; Sahin, E. Turhanlar; Özhan, GüneşThe Wnt/β-catenin signaling pathway, an evolutionarily conserved and pivotal pathway associated with synapse formation in adulthood, plays a crucial role in Alzheimer's disease (AD). AD, marked by various pathologies, is primarily linked to the accumulation of extracellular beta-amyloid plaques. The interplay between this accumulation and disruptions in the Wnt/β-catenin signaling pathway triggers synaptic degeneration, resulting in synaptic dysfunction and AD progression. In this study, we modeled AD induced by the Aβ42 peptide using adult transgenic (6XTCF) zebrafish. To establish the zebrafish AD model, we employed cerebroventricular microinjection (CVMI) with the Aβ42 peptide. Fish, anesthetized prior to CVMI, were positioned on a stable platform, and the Aβ42 peptide was injected into the telencephalon region of the brain by a capillary needle. Brain samples were collected on 1, 3, 4, 7, and 14 days post-CVMI (dpi) to analyze changes in Aβ42 peptide accumulation, the immune system response, synaptic degeneration, apoptosis, and the expression of genes related to proliferation using qPCR and immunofluorescent staining. To examine the role of the Wnt/β-catenin signaling pathway in the molecular mechanism of AD development, fish exhibiting high levels of regeneration on days 7 and 14 were treated with the IWR-1 drug, which inhibits the Wnt/β-catenin signaling by stabilizing the Axin2 protein, thereby suppressing the regenerative response. Our results revealed that the AD model manifested on 3dpi, with the regenerative response reaching its peak on 7dpi and 14dpi. Treatment with IWR-1 resulted in increased Aβ42 accumulation, accelerated synaptic degeneration, and elevated cell deaths in fish where the Wnt signaling pathway was inhibited. In conclusion, our adult zebrafish AD model is poised to elucidate the molecular mechanisms connecting the Wnt signaling pathway and AD, thereby contributing to the development of alternative therapeutic approaches for AD patients.Article Citation - WoS: 6Epitranscriptomics M<sup>6</Sup>a Analyses Reveal Distinct M<sup>6</Sup>a Marks Under Tumor Necrosis Factor Α (tnf-Α) Apoptotic Conditions in Hela Cells(Wiley, 2024) Akçaöz Alasar, Azime; Tüncel, Özge; Sağlam, Buket; Gazaloğlu, Yasemin; Atbinek, Melis; Çağıral, Umut; Akgül, BünyaminTumor necrosis factor-alpha (TNF-alpha) is a ligand that induces both intrinsic and extrinsic apoptotic pathways in HeLa cells by modulating complex gene regulatory mechanisms. However, the full spectrum of TNF-alpha-modulated epitranscriptomic m(6)A marks is unknown. We employed a genomewide approach to examine the extent of m(6)A RNA modifications under TNF-alpha-modulated apoptotic conditions in HeLa cells. miCLIP-seq analyses revealed a plethora of m(6)A marks on 632 target mRNAs with an enrichment on 99 mRNAs associated with apoptosis. Interestingly, the m(6)A RNA modification patterns were quite different under cisplatin- and TNF-alpha-mediated apoptotic conditions. We then examined the abundance and translational efficiencies of several mRNAs under METTL3 knockdown and/or TNF-alpha treatment conditions. Our analyses showed changes in the translational efficiency of TP53INP1 mRNA based on the polysome profile analyses. Additionally, TP53INP1 protein amount was modulated by METTL3 knockdown upon TNF-alpha treatment but not CP treatment, suggesting the existence of a pathway-specific METTL3-TP53INP1 axis. Congruently, METLL3 knockdown sensitized HeLa cells to TNF-alpha-mediated apoptosis, which was also validated in a zebrafish larval xenograft model. These results suggest that apoptotic pathway-specific m(6)A methylation marks exist in cells and TNF-alpha-METTL3-TP53INP1 axis modulates TNF-alpha-mediated apoptosis in HeLa cells.Article Citation - WoS: 14Citation - Scopus: 14Comparative Membrane Lipidomics of Hepatocellular Carcinoma Cells Reveals Diacylglycerol and Ceramide as Key Regulators of Wnt/Β-catenin Signaling and Tumor Growth(Wiley, 2023) Heger, Guillaume; Azbazdar, Yağmur; Demirci, Yeliz; İpekgil, Doğaç; Karabiçici, Mustafa; Özhan, GüneşHepatocellular carcinoma (HCC) is largely associated with aberrant activation of Wnt/beta-catenin signaling. Nevertheless, how membrane lipid composition is altered in HCC cells with abnormal Wnt signaling remains elusive. Here, by exploiting comprehensive lipidome profiling, we unravel the membrane lipid composition of six different HCC cell lines with mutations in components of Wnt/beta-catenin signaling, leading to differences in their endogenous signaling activity. Among the differentially regulated lipids are diacylglycerol (DAG) and ceramide, which were downregulated at the membrane of HCC cells after Wnt3a treatment. DAG and ceramide enhanced Wnt/b-catenin signaling by inducing caveolin-mediated endocytosis of the canonical Wnt-receptor complex, while their depletion suppressed the signaling activity along with a reduction of caveolin-mediated endocytosis in SNU475 and HepG2 cells. Moreover, depletion of DAG and ceramide significantly impeded the proliferation, tumor growth, and in vivo migration capacity of SNU475 and HepG2 cells. This study, by pioneering plasma membrane lipidome profiling in HCC cells, exhibits the remarkable potential of lipids to correct dysregulated signaling pathways in cancer and stop abnormal tumor growth.Article Citation - WoS: 20Citation - Scopus: 21Progression of Irradiated Mesenchymal Stromal Cells From Early To Late Senescence: Changes in Sasp Composition and Anti-Tumour Properties(Wiley, 2023) Alessio, Nicola; Acar, Mustafa Burak; Squillaro, Tiziana; Aprile, Domenico; Ayaz Güner, Şerife; Di Bernardo, Giovanni; Özcan, ServetGenotoxic injuries converge on senescence-executive program that promotes production of a senescence-specific secretome (SASP). The study of SASP is particularly intriguing, since through it a senescence process, triggered in a few cells, can spread to many other cells and produce either beneficial or negative consequences for health. We analysed the SASP of quiescent mesenchymal stromal cells (MSCs) following stress induced premature senescence (SIPS) by ionizing radiation exposure. We performed a proteome analysis of SASP content obtained from early and late senescent cells. The bioinformatics studies evidenced that early and late SASPs, besides some common ontologies and signalling pathways, contain specific factors. In spite of these differences, we evidenced that SASPs can block in vitro proliferation of cancer cells and promote senescence/apoptosis. It is possible to imagine that SASP always contains core components that have an anti-tumour activity, the progression from early to late senescence enriches the SASP of factors that may promote SASP tumorigenic activity only by interacting and instructing cells of the immune system. Our results on Caco-2 cancer cells incubated with late SASP in presence of peripheral white blood cells strongly support this hypothesis. We evidenced that quiescent MSCs following SIPS produced SASP that, while progressively changed its composition, preserved the capacity to block cancer growth by inducing senescence and/or apoptosis only in an autonomous manner.Article Citation - WoS: 2Citation - Scopus: 2Identification of Novel Arsenic Resistance Genes in Yeast(Wiley, 2022) Işık, Esin; Balkan, Çiğdem; Karl, Vivien; Karakaya, Hüseyin Çağlar; Hua, Sansan; Rauch, Sebastien; Tamás, Markus J; Koç, AhmetArsenic is a toxic metalloid that affects human health by causing numerous diseases and by being used in the treatment of acute promyelocytic leukemia. Saccharomyces cerevisiae (budding yeast) has been extensively utilized to elucidate the molecular mechanisms underlying arsenic toxicity and resistance in eukaryotes. In this study, we applied a genomic DNA overexpression strategy to identify yeast genes that provide arsenic resistance in wild-type and arsenic-sensitive S. cerevisiae cells. In addition to known arsenic-related genes, our genetic screen revealed novel genes, including PHO86, VBA3, UGP1, and TUL1, whose overexpression conferred resistance. To gain insights into possible resistance mechanisms, we addressed the contribution of these genes to cell growth, intracellular arsenic, and protein aggregation during arsenate exposure. Overexpression of PHO86 resulted in higher cellular arsenic levels but no additional effect on protein aggregation, indicating that these cells efficiently protect their intracellular environment. VBA3 overexpression caused resistance despite higher intracellular arsenic and protein aggregation levels. Overexpression of UGP1 led to lower intracellular arsenic and protein aggregation levels while TUL1 overexpression had no impact on intracellular arsenic or protein aggregation levels. Thus, the identified genes appear to confer arsenic resistance through distinct mechanisms but the molecular details remain to be elucidated.Conference Object The Importance of Mirna Expressions in Infertilty(Wiley, 2016) Gökalp, S.; Akgül, Bünyamin; Özçakır, T.; Vatansever, H. S.Implantation process is controlled with endometrium, factors secreted by the embryos and in accordance with these factors embryo and/or endometrium via receptors on. More than 700 human MicroRNA (miRNAs) that are small noncoding RNAs were shown to play an important role in intracelluler cycle regulation in both normal and pathological conditions. In this study we aim to identify miRNAs and controlling molecules expressions in different time period of endometrium in fertile and infertile cases.Conference Object Functional Characterization of Clinically Relevant Novel Mutations in Atp7b Gene Using the Saccharomyces Cerevisiae Model(Wiley, 2016) Şimşek Papur, Özlenen; Terzioğlu, Orhan; Koç, AhmetWilson disease is an autosomal recessive disorder of copper metabolism characterized as neurodegeneration and liver abnormalities. It is caused by defects in the ATP7B gene. ATP7B is responsible for the sequestration of Cu into secretory vesicles, and this function is exhibited by the orthologous Ccc2p in the yeast. We aimed to characterize clinically-relevant novel mutations of p.T788I, p.V1036I and p.R1038G-fsX8 in yeast lacking the CCC2 gene.