Yazar "Gokce, Isa" seçeneğine göre listele

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    Development of recombinant protein-based nanoparticle systems for inducing tumor cell apoptosis: In vitro evaluation of their cytotoxic and apoptotic effects on cancer cells
    (Elsevier, 2024) Kaplan, Ozlem; Gok, Mehmet Koray; Pekmez, Murat; Tayhan, Secil Erden; Ozguemues, Saadet; Gokce, Isa; Arda, Nazli
    Myeloid leukemia cell differentiation protein (Mcl-1) is a B -cell lymphoma 2 (Bcl-2) family antiapoptotic protein that regulates cellular apoptosis. Mcl-1 expression is important for cancer cell survival and a prospective target in cancer treatment. Bcl-2 homology 3 (BH3) mimetic peptides, such as the Mcl-1-specific MS1 peptide that targets conserved BH3 domains, are highly specific Mcl-1 inhibitors. However, the application of these peptides is limited due to their metabolic instability, degradation by cellular proteases, and low cell permeability. In this study, it was aimed to form nanostructures to increase the cellular uptake and stability of the Mcl-1 inhibitor MS1 peptide. The Bim BH3 mimetic MS1 peptide was produced recombinantly in fusion with mNeonGreen fluorescent protein and polyhistidine (6xHisTag). Self -assembled protein nanoparticles were fabricated from the recombinant MS1-mNeonGreen protein. Furthermore, the MS1-mNeonGreen protein was encapsulated into polymeric nanoparticles. The cytotoxic effects of these nanoparticles on cancer cells [cervical cancer cell line (HeLa), lung cancer cell line (A549) and breast cancer cell line (MDA-MB-231)] and healthy cell line [Human umbilical vein endothelial cells (HUVEC)] was analyzed by MTT test. The apoptotic effect of nanoparticles on these cells was investigated by determining the antiapoptotic and proapoptotic protein levels. As a result, it was revealed that the nanoparticles have a specific cytotoxic effect against the cells and induce apoptosis.
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    Investigation of the Usability of Polymeric Nanoparticle-Based Transfection Agent for CRISPR/CAS9 in HUVEC Cell Line
    (2025) Imamoglu, Rızvan; Kaplan, Ozlem; Gök, Mehmet Koray; Gokce, Isa
    Genome editing technology is a promising, popular technology for diagnosing and treating many diseases. One of the most popular techniques utilized in genome editing research nowadays is the CRISPR/Cas system. The CRISPR/Cas system holds considerable potential for diagnostic and therapeutic applications due to its ease of use, speed, and affordability. The safe and effective delivery of the CRISPR-based genome editing system to the intended human body cells is one of the system's problems. This study investigated the silencing of the COX-2 gene via the CRISPR/Cas system using a P?AE-based transfection agent in the HUVEC cell line. Western blot analysis was performed to confirm COX-2 gene silencing in the HUVEC cell line, and the effects of COX-2 gene silencing on cell migration in these cells were examined. As a result, the transfection efficiency of the P?AE-based transfection agent for the HUVEC cell line was determined as 90-95%, and the CRISPR efficiency was calculated as 57.12% based on the Western blot results. It was revealed that the P?AE-based nanoparticles used in this study can be used as a good transfection agent in CRISPR/Cas-mediated genome editing in the HUVEC cell line, especially in plasmid transfection.
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    Soluble Expression of Human Granulocyte Colony Stimulating Factor (hG-CSF) in Escherichia coli Expression System
    (2025) Songur, Mustafa; Kaplan, Ozlem; Imamoglu, Rızvan; Gokce, Isa
    Human granulocyte colony stimulating factor (hG-CSF) is a hematological growth factor that plays a crucial role in neutrophil production and differentiation. Some foreign biomolecules, especially of human origin, such as hG-CSF, sometimes aggregate because of different factors during expression and create inclusion bodies in Escherichia coli (E. coli). Refolding process is commonly used to recover these very valuable molecules, but still significant amounts of protein remain unusable. Refolding procedures are frequently costly, time-consuming, and not fully efficient. Therefore, the use of molecular chaperones to improve soluble expression of proteins was evaluated in the study. In this context, hG-CSF was co-expressed with five chaperone plasmid systems (pGro7, pG-KJE8, pG-Tf2, pKJE7, pTf16) to ensure the expression of hG-CSF in soluble form. Among these, the pKJE7 plasmid was found to be the most effective in obtaining hG-CSF in soluble form, yielding 92% purity after Ni-NTA affinity chromatography purification. The total yield of hG-CSF obtained was 1.6 mg per 1 L bacterial culture. The biological activity of the soluble hG-CSF was evaluated in human umbilical vein endothelial cells (HUVECs). A 24-hour interaction of hG-CSF with HUVECs resulted in a significant increase in cell viability at all applied doses, demonstrating its bioactivity. As a result, hG-CSF, which previously aggregated as an inclusion body in the E. coli expression system, was correctly folded by co-expression with chaperone proteins were obtained as more efficient and purer.