Browsing by Author "Yaylak, Bilge"

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Indentification of circular ribonucleic acids differentially expressed in apoptotic HeLa cells
(Izmir Institute of Technology, 2018-07) Yaylak, Bilge; Akgül, Bünyamin
Apoptosis is a mechanism of programmed cell death that is essential for survival, homeostatis and development. Various protein coding genes and non-coding RNAs were reported as apoptosis regulators. However, the potential roles of circular RNA in the regulation of apoptosis are still unknown. In this study, we have performed transcriptomics study to reveal differentially expressed, pathway-drug specific and/or global circRNAs in apoptotic HeLa cells. Cisplatin (CP), doxorubicin (DOX), Fas mAb(FAS) and TNF-alpha (TNF-a) were used to trigger apoptosis in HeLa cells. Apoptosis rates of three replicates of treatment and control cells were measured by flow cytometry and differentially expressed circular RNAs were identified by deep RNA sequencing. Circular RNA candidates were firstly sorted based on their significance according to pad j value, further classified based on fold change, pathway-drug specificity and source genes. Then, circular RNA candidates were analysed bioinformatically to obtain their coding potential, potential miRNA binding sites and involvement in possible apoptotic pathways. Furthermore, divergent primers were designed to validate backsplicing junction sequence of circular RNA candidates. RNAse R treatment was used to eliminate linear transcripts and enrich circular RNAs. The expression of candidate circular RNAs was analysed RNAse R treated samples. Backsplicing junctions of positive circular control circ-HIPK3 was validated by TA cloning and sequencing. Differential expression of positive control (circ-HIPK3), candidate-8 and candidate-6 were validated by quantitative PCR.
Citation Count: 3
Noncoding RNAs in apoptosis: identification and function
(Tubitak Scientific & Technological Research Council Turkey, 2022) Tuncel, Ozge; Kara, Merve; Yaylak, Bilge; Erdogan, Ipek; Akgul, Bunyamin; Akgül, Bünyamin
Apoptosis is a vital cellular process that is critical for the maintenance of homeostasis in health and disease. The derailment of apoptotic mechanisms has severe consequences such as abnormal development, cancer, and neurodegenerative diseases. Thus, there exist complex regulatory mechanisms in eukaryotes to preserve the balance between cell growth and cell death. Initially, protein coding genes were prioritized in the search for such regulatory macromolecules involved in the regulation of apoptosis. However, recent genome annotations and transcriptomics studies have uncovered a plethora of regulatory noncoding RNAs that have the ability to modulate not only apoptosis but also many other biochemical processes in eukaryotes. In this review article, we will cover a brief summary of apoptosis and detection methods followed by an extensive discussion on microRNAs, circular RNAs, and long noncoding RNAs in apoptosis.
Citation Count: 6
Transcriptomics Analysis of Circular RNAs Differentially Expressed in Apoptotic HeLa Cells
(Frontiers Media Sa, 2019) Yaylak, Bilge; Erdogan, Ipek; Akgul, Bunyamin; Akgül, Bünyamin
Apoptosis is a form of regulated cell death that plays a critical role in survival and developmental homeostasis. There are numerous reports on regulation of apoptosis by protein-coding genes as well as small non-coding RNAs, such as microRNAs. However, there is no comprehensive investigation of circular RNAs (circRNA) that are differentially expressed under apoptotic conditions. We have performed a transcriptomics study in which we first triggered apoptosis in HeLa cells through treatment with four different agents, namely cisplatin, doxorubicin, TNF-alpha and anti-Fas mAb. Total RNAs isolated from control as well as treated cells were treated with RNAse R to eliminate the linear RNAs. The remaining RNAs were then subjected to deep-sequencing to identify differentially expressed circRNAs. Interestingly, some of the dys-regulated circRNAs were found to originate from protein-coding genes well-documented to regulate apoptosis. A number of candidate circRNAs were validated with qPCR with or without RNAse R treatment as well. We then took advantage of bioinformatics tools to investigate the coding potential of differentially expressed RNAs. Additionally, we examined the candidate circRNAs for the putative miRNA-binding sites and their putative target mRNAs. Our analyses point to a potential for circRNA-mediated sponging of miRNAs known to regulate apoptosis. In conclusion, this is the first transcriptomics study that provides a complete circRNA profile of apoptotic cells that might shed light onto the potential role of circRNAs in apoptosis.