Araştırma Çıktıları

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Author: search.filters.author.Gerlevik, UmutHas files: Yes

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    Mutations and Copy Number Alterations in IDH Wild-Type Glioblastomas Are Shaped by Different Oncogenic Mechanisms
    (MDPI, 2020-01-01) Ulgen, Ege; Karacan, Sila; Gerlevik, Umut; Can, Ozge; Bilguvar, Kaya; Oktay, Yavuz; B. Akyerli, Cemaliye; K. Yuksel, Sirin; E. Danyeli, Ayca; Tihan, Tarik; Sezerman, O. Ugur; Yakicier, M. Cengiz; Pamir, M. Necmettin; Ozduman, Koray
    Little is known about the mutational processes that shape the genetic landscape of gliomas. Numerous mutational processes leave marks on the genome in the form of mutations, copy number alterations, rearrangements or their combinations. To explore gliomagenesis, we hypothesized that gliomas with different underlying oncogenic mechanisms would have differences in the burden of various forms of these genomic alterations. This was an analysis on adult diffuse gliomas, but IDH-mutant gliomas as well as diffuse midline gliomas H3-K27M were excluded to search for the possible presence of new entities among the very heterogenous group of IDH-WT glioblastomas. The cohort was divided into two molecular subsets: (1) Molecularly-defined GBM (mGBM) as those that carried molecular features of glioblastomas (including TERT promoter mutations, 7/10 pattern, or EGFR-amplification), and (2) those who did not (others). Whole exome sequencing was performed for 37 primary tumors and matched blood samples as well as 8 recurrences. Single nucleotide variations (SNV), short insertion or deletions (indels) and copy number alterations (CNA) were quantified using 5 quantitative metrics (SNV burden, indel burden, copy number alteration frequency-wGII, chromosomal arm event ratio-CAER, copy number amplitude) as well as 4 parameters that explored underlying oncogenic mechanisms (chromothripsis, double minutes, microsatellite instability and mutational signatures). Findings were validated in the TCGA pan-glioma cohort. mGBM and ``Others{''} differed significantly in their SNV (only in the TCGA cohort) and CNA metrics but not indel burden. SNV burden increased with increasing age at diagnosis and at recurrences and was driven by mismatch repair deficiency. On the contrary, indel and CNA metrics remained stable over increasing age at diagnosis and with recurrences. Copy number alteration frequency (wGII) correlated significantly with chromothripsis while CAER and CN amplitude correlated significantly with the presence of double minutes, suggesting separate underlying mechanisms for different forms of CNA.
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    Understanding the impacts of self-shuffling approach on structure and function of shuffled endoglucanase enzyme via MD simulations
    (WALTER DE GRUYTER GMBH, 2020-01-01) Yenenler, Asli; Gerlevik, Umut; Sezerman, Ugur
    Objective: We identify the impacts of structural differences on functionality of EG3\_S2 endoglucanase enzyme with MD studies. The results of previous experimental studies have been explained in details with computational approach. The objective of this study is to explain the functional differences between shuffled enzyme (EG3\_S2) and its native counterpart (EG3\_nat) from Trichoderma reseei, via Molecular Dynamics approach. Materials and methods: For this purpose, we performed MD simulations along 30 ns at three different reaction temperatures collected as NpT ensemble, and then monitored the backbone motion, flexibilities of residues, and intramolecular interactions of EG3\_S2 and EG3\_nat enzymes. Results: According to MD results, we conclude that EG3 S2 and EG3\_nat enzymes have unique RMSD patterns, e.g. RMSD pattern of EG3\_S2 is more dynamic than that of EG3\_nat at all temperatures. In addition to this dynamicity, EG3 S2 establishes more salt bridge interactions than EG3\_nat. Conclusion: By taking these results into an account with the preservation of catalytic Glu residues in a proper manner, we explain the structural basis of differences between shuffled and native enzyme via molecular dynamic studies.