Molecular Biology and Genetics / Moleküler Biyoloji ve Genetik
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Article Citation - WoS: 5Citation - Scopus: 5A Microrna-Regulated Transcriptional State Defines Intratumoral Cd8+t Cells That Respond To Immunotherapy(Cell Press, 2025) Tang, William W.; Battistone, Ben; Bauer, Kaylyn M.; Weis, Allison M.; Barba, Cindy; Fadlullah, Muhammad Zaki Hidayatullah; O'Connell, Ryan M.The rising incidence of advanced-stage colorectal cancer (CRC) and poor survival outcomes necessitate new and effective therapies. Immune checkpoint inhibitors (ICIs), specifically anti-PD-1 therapy, show promise, yet clinical determinants of a positive response are suboptimal. Here, we identify microRNA-155 (miR-155) as necessary for CD8+ T cell-infiltrated tumors through an unbiased in vivo CRISPR-Cas9 screen identifying functional tumor antigen-specific CD8+ T cell-expressed microRNAs. T cell miR-155 is required for anti-PD-1 responses and for a vital intratumor CD8+ T cell differentiation cascade by repressing Ship-1, inhibiting Tcf-1 and stemness, and subsequently enhancing Cxcr6 expression, anti-tumor immunity, and effector functions. Based on an underlying miR-155-dependent CD8+ T cell transcriptional profile, we identify a gene signature that predicts ICI responses across 12 diverse cancers. Together, our findings support a model whereby miR155 serves as a central regulator of CD8+ T cell-dependent cancer immunity and ICI responses that may be leveraged for future therapeutics.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: 6Citation - Scopus: 5Epitranscriptomics M6a Analyses Reveal Distinct M6a Marks Under Tumor Necrosis Factor Α (tnf-Α) Apoptotic Conditions in Hela Cells(Wiley, 2024) Akçaöz Alasar, Azime; Tuncel, Özge; Sağlam, Buket; Gazaloğlu, Yasemin; Atbinek, Melis; Çağıral, Umut; İşcan, Evin; Özhan, Güneş; 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: 8Citation - Scopus: 8Canonical Wnt and Tgf-β/Bmp Signaling Enhance Melanocyte Regeneration but Suppress Invasiveness, Migration, and Proliferation of Melanoma Cells(Frontiers Media S.A., 2023) Katkat, Esra; Demirci, Yeliz; Heger, Guillaume; Karagülle, Doğa; Papatheodorou, Irene; Brazma, Alvis; Özhan, GüneşMelanoma is the deadliest form of skin cancer and develops from the melanocytes that are responsible for the pigmentation of the skin. The skin is also a highly regenerative organ, harboring a pool of undifferentiated melanocyte stem cells that proliferate and differentiate into mature melanocytes during regenerative processes in the adult. Melanoma and melanocyte regeneration share remarkable cellular features, including activation of cell proliferation and migration. Yet, melanoma considerably differs from the regenerating melanocytes with respect to abnormal proliferation, invasive growth, and metastasis. Thus, it is likely that at the cellular level, melanoma resembles early stages of melanocyte regeneration with increased proliferation but separates from the later melanocyte regeneration stages due to reduced proliferation and enhanced differentiation. Here, by exploiting the zebrafish melanocytes that can efficiently regenerate and be induced to undergo malignant melanoma, we unravel the transcriptome profiles of the regenerating melanocytes during early and late regeneration and the melanocytic nevi and malignant melanoma. Our global comparison of the gene expression profiles of melanocyte regeneration and nevi/melanoma uncovers the opposite regulation of a substantial number of genes related to Wnt signaling and transforming growth factor beta (TGF-beta)/(bone morphogenetic protein) BMP signaling pathways between regeneration and cancer. Functional activation of canonical Wnt or TGF-beta/BMP pathways during melanocyte regeneration promoted melanocyte regeneration but potently suppressed the invasiveness, migration, and proliferation of human melanoma cells in vitro and in vivo. Therefore, the opposite regulation of signaling mechanisms between melanocyte regeneration and melanoma can be exploited to stop tumor growth and develop new anti-cancer therapies.Article Citation - WoS: 7Citation - Scopus: 6Addition of Exogenous Diacylglycerol Enhances Wnt/Β-catenin Signaling Through Stimulation of Macropinocytosis(Elsevier, 2023) Azbazdar, Yağmur; Tejeda-Munoz, Nydia; Monka, Julia C.; Dayrit, Alex; Binder, Grace; De Robertis, Edward M.; Özhan, GüneşActivation of Wnt signaling triggers macropinocytosis and drives many tumors. We now report that the exogenous addition of the second messenger lipid sn-1,2 DAG to the culture medium rapidly induces macropinocytosis. This is accompanied by potentiation of the effects of added Wnt3a recombinant protein or the glycogen synthase kinase 3 (GSK3) inhibitor lithium chloride (LiCl, which mimics Wnt signaling) in luciferase transcriptional reporter assays. In a colorectal carcinoma cell line in which mutation of adenomatous polyposis coli (APC) causes constitutive Wnt signaling, DAG addition increased levels of nuclear β-catenin, and this increase was partially inhibited by an inhibitor of macropinocytosis. DAG also expanded multivesicular bodies marked by the tetraspan protein CD63. In an in vivo situation, microinjection of DAG induced Wnt-like twinned body axes when co-injected with small amounts of LiCl into Xenopus embryos. These results suggest that the DAG second messenger plays a role in Wnt-driven cancer progression. © 2023 The Author(s)Article Citation - WoS: 2Citation - Scopus: 2Gas Phase Fragmentation Behavior of Proline in Macrocyclic B7 Ions(American Chemical Society, 2023) Taşoğlu, Çağdaş; Arslanoğlu, Alper; Yalçın, TalatThefragmentation characteristics of b (7) ionsproduced from proline-containing heptapeptides have been studiedin detail. The study has utilized the following C-terminally amidatedmodel peptides: PA(6), APA(5), A(2)PA(4), A(3)PA(3), A(4)PA(2), A(5)PA, A(6)P, PYAGFLV, PAGFLVY, PGFLVYA, PFLVYAG,PLVYAGF, PVYAGFL, YPAGFLV, YAPGFLV, YAGPFLV, YAGFPLV, YAGFLPV, YAGFLVP,PYAFLVG, PVLFYAG, A(2)PXA(3), and A(2)XPA(3) (where X = C, D, F, G, L, V, and Y, respectively). The resultshave shown that b (7) ions undergo head-to-tailcyclization and form a macrocyclic structure. Under the collision-induceddissociation (CID) condition, it generates nondirect sequence ionsregardless of the position of the proline and the neighboring aminoacid residues. This study highlights the unusual and unique fragmentationbehavior of proline-containing heptapeptides. Following the head-to-tailcyclization, the ring opens up and places the proline residue in theN-terminal position while forming a regular oxazolone form of b (2) ions for all peptide series. Then, the fragmentationreaction pathway is followed by the elimination of proline with itsC-terminal neighbor residue as an oxazolone (e.g., PXoxa) for all proline-containing peptide series.Article Citation - WoS: 28Citation - Scopus: 30Senescence-Induced Immune Remodeling Facilitates Metastatic Adrenal Cancer in a Sex-Dimorphic Manner(Springer, 2023) Warde, Kate M.; Smith, Lorenzo J.; Liu, Lihua; Stubben, Chris J.; Lohman, Brian K.; Willett, Parker W.; Ammer, Julia L.; Castaneda Hernandez, Guadalupe; Imodoye, Sikiru O.; Zhang, Chenge; Jones, Kara D.; Converso Baran, Kimber; Ekiz, H. AtakanThe mechanisms underlying the influence of aging on cancer are incompletely understood. Warde et al. establish a new model of age- and sex-dependent adrenal cancer. Their work uncovers a tumor-protective role for myeloid immune cells that is enhanced by androgens. Aging markedly increases cancer risk, yet our mechanistic understanding of how aging influences cancer initiation is limited. Here we demonstrate that the loss of ZNRF3, an inhibitor of Wnt signaling that is frequently mutated in adrenocortical carcinoma, leads to the induction of cellular senescence that remodels the tissue microenvironment and ultimately permits metastatic adrenal cancer in old animals. The effects are sexually dimorphic, with males exhibiting earlier senescence activation and a greater innate immune response, driven in part by androgens, resulting in high myeloid cell accumulation and lower incidence of malignancy. Conversely, females present a dampened immune response and increased susceptibility to metastatic cancer. Senescence-recruited myeloid cells become depleted as tumors progress, which is recapitulated in patients in whom a low myeloid signature is associated with worse outcomes. Our study uncovers a role for myeloid cells in restraining adrenal cancer with substantial prognostic value and provides a model for interrogating pleiotropic effects of cellular senescence in cancer.Article Citation - WoS: 3Citation - Scopus: 3Her2-Specific Peptide (ltvspwy) and Antibody (herceptin) Targeted Core Cross-Linked Micelles for Breast Cancer: a Comparative Study(MDPI, 2023) Bayram, N.N.; Ulu, G.T.; Abdulhadi, N.A.; Gürdap, S.; İşoğlu, İ.A.; Baran, Yusuf; İşoğlu, S.D.This study aims to prepare a novel breast cancer-targeted micelle-based nanocarrier, which is stable in circulation, allowing intracellular drug release, and to investigate its cytotoxicity, apoptosis, and cytostatic effects, in vitro. The shell part of the micelle is composed of zwitterionic sulfobetaine ((N-3-sulfopropyl-N,N-dimethylamonium)ethyl methacrylate), while the core part is formed by another block, consisting of AEMA (2-aminoethyl methacrylamide), DEGMA (di(ethylene glycol) methyl ether methacrylate), and a vinyl-functionalized, acid-sensitive cross-linker. Following this, a targeting agent (peptide (LTVSPWY) and antibody (Herceptin®)), in varying amounts, were coupled to the micelles, and they were characterized by 1H NMR, FTIR (Fourier-transform infrared spectroscopy), Zetasizer, BCA protein assay, and fluorescence spectrophotometer. The cytotoxic, cytostatic, apoptotic, and genotoxic effects of doxorubicin-loaded micelles were investigated on SKBR-3 (human epidermal growth factor receptor 2 (HER2)-positive) and MCF10-A (HER2-negative). According to the results, peptide-carrying micelles showed a higher targeting efficiency and better cytostatic, apoptotic, and genotoxic activities than antibody-carrying and non-targeted micelles. Also, micelles masked the toxicity of naked DOX on healthy cells. In conclusion, this nanocarrier system has great potential to be used in different drug-targeting strategies, by changing targeting agents and drugs. © 2023 by the authors.Conference Object Citation - WoS: 1Differential Susceptibility To Senescence in Cart Cells Based on Co-Stimulatory Signaling(American Society of Hematology, 2022) Can, İsmail; Sakemura, Reona Leo; Manriquez-Roman, Claudia; Sirpilla, Olivia; Stewart, Carli M.; Yun, Kun; Cox, Michelle J.; Ekiz, AtakanCD19-directed chimeric antigen receptor (CART19) cells have emerged as a potentially curative immunotherapy in a subset of patients with hematological malignancies. While initial responses are impressive, the majority of responsive patients relapse within a year. Recent studies suggest that CART cells are susceptible to states of dysfunction. We aimed to study the development of T cell senescence in CART cells using similar constructs to the FDA-approved therapies, CART19-BBζ and CART19-28ζ, to determine the impact of co-stimulatory domains on CART cell senescence. We developed an in vitro model for repeated CART cell activation followed by rest to study the development of senescence and its impact on effector T cell functions. We examined CART cell immunophenotype, cell cycle regulators, and transcriptomic profile on days 0 (T cell), D8 (standard CART cell), 15 (after one activation cycle) and 22 (after two activation cycles).Article Citation - WoS: 22Citation - Scopus: 23A Single-Amino Acid Substitution in the Adaptor Lat Accelerates Tcr Proofreading Kinetics and Alters T-Cell Selection, Maintenance and Function(Nature Portfolio, 2023) Lo, Wan-Lin; Ekiz, Hüseyin Atakan; Kuhlmann, Miriam; Rizzuto, Gabrielle; Ekiz, H. Atakan; Kolawole, Elizabeth M.; Revelo, Monica P.; Andargachew, RakiebMature T cells must discriminate between brief interactions with self-peptides and prolonged binding to agonists. The kinetic proofreading model posits that certain T-cell antigen receptor signaling nodes serve as molecular timers to facilitate such discrimination. However, the physiological significance of this regulatory mechanism and the pathological consequences of disrupting it are unknown. Here we report that accelerating the normally slow phosphorylation of the linker for activation of T cells (LAT) residue Y136 by introducing an adjacent Gly135Asp alteration (LAT(G135D)) disrupts ligand discrimination in vivo. The enhanced self-reactivity of LAT(G135D) T cells triggers excessive thymic negative selection and promotes T-cell anergy. During Listeria infection, LAT(G135D) T cells expand more than wild-type counterparts in response to very weak stimuli but display an imbalance between effector and memory responses. Moreover, despite their enhanced engagement of central and peripheral tolerance mechanisms, mice bearing LAT(G135D) show features associated with autoimmunity and immunopathology. Our data reveal the importance of kinetic proofreading in balancing tolerance and immunity. Lo and colleagues provide evidence for the TCR kinetic proofreading model by LAT Gly135Asp alteration to reveal functional consequences of altered kinetics in TCR activation in thymic selection and mature T-cell responses.