Browsing by Author "Bozaykut, Perinur"

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Cellular stress responses of long-lived and cancer-resistant naked mole-rats
(WALTER DE GRUYTER GMBH, 2021-01-01) Bozaykut, Perinur
Objectives: Some organisms are long-lived and naturally resistant to cancer such as naked mole-rats (NMRs). Studies have shown that these animals can better tolerate stress due to mechanisms, such as upregulation of antioxidant pathways and improved proteostasis. In the present study, we aimed to analyze the tolerance against stress and the cellular mechanisms related to the stress response in NMR cells comparative to mouse cells. Materials and methods: NMR and mouse fibroblasts were exposed to cellular stresses including H2O2 and/or NaNO3 and the viability of the cells were analyzed. In addition messanger RNA (mRNA) expression of antioxidant transcription factor Nuclear factor erythroid-derived 2-like 2 (Nrf2) and its target gene NAD(P)H quinone dehydrogenase 1 (NQO1) were determined by qRT-PCR and comprehensive analysis of stress-related gene expression was performed by RNA-Sequencing in fibroblasts and induced pluripotent stem cells (iPSC). Results: Surprisingly, NMR fibroblasts were found to be more sensitive than mouse cells to H2O2 and NaNO3. Furthermore, it was shown that fibroblasts and iPSCs mainly aren't identical in the expression pattern of cellular defense signaling and several factors are mainly downregulated in NMR iPSCs. Conclusions: Collectively, the data gained from the present study help to improve the understanding of evolved mechanisms that contribute to stress resistance, aging and cancer.
HSP70 Inhibition Leads to the Activation of Proteasomal System under Mild Hyperthermia Conditions in Young and Senescent Fibroblasts
(HINDAWI LTD, 2020-01-01) Bozaykut, Perinur; Sozen, Erdi; Kaga, Elif; Ece, Asli; Ozaltin, Esra; Bergquist, Jonas; Ozer, Nesrin Kartal; Yilmaz, Betul Karademir
Aging has been characterized with the accumulation of oxidized proteins, as a consequence of progressive decline in proteostasis capacity. Among others, proteasomal system is an efficient protein turnover complex to avoid aggregation of oxidized proteins. Heat shock protein 70 (HSP70) is another critical player that is involved in some key processes including the correct folding of misfolded proteins and targeting aggregated proteins to the proteasome for rapid degradation. The aim of this study was to determine the role of proteasomal system and heat shock proteins to maintain proteome balance during replicative senescence in mild hyperthermia conditions. Our results demonstrated that HSP40/70 machinery is induced by mild hyperthermia conditions independent from senescence conditions. Since HSP70 is largely responsible for the rapidly inducible cell protection following hyperthermia, the activation of ``heat shock response{''} resulted in the elevation of HSP40/70 expressions as well as the proteasome activity. Interestingly, when HSP70 expression was inhibited, increased proteasomal activation was shown to be responsive to mild hyperthermia. Since HSP70 is involved in various stress-related pathways such as oxidative and endoplasmic reticulum stress, depletion of HSP70 expression may induce proteasomal degradation to maintain proteome balance of the cell. Thus, our data suggests that in mild heat stress conditions, molecular chaperone HSP70 plays an important role to avoid protein oxidation and aggregation
Transcriptomics and Proteomics Analyses Reveal JAK Signaling and Inflammatory Phenotypes during Cellular Senescence in Blind Mole Rats: The Reflections of Superior Biology
(MDPI, 2022-01-01) Inci, Nurcan; Akyildiz, Erdogan Oguzhan; Bulbul, Abdullah Alper; Turanli, Eda Tahir; Akgun, Emel; Baykal, Ahmet Tarik; Colak, Faruk; Bozaykut, Perinur
The blind mole rat (BMR), a long-living subterranean rodent, is an exceptional model for both aging and cancer research since they do not display age-related phenotypes or tumor formation. The Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling is a cytokine-stimulated pathway that has a crucial role in immune regulation, proliferation, and cytokine production. Therefore, the pathway has recently attracted interest in cellular senescence studies. Here, by using publicly available data, we report that JAK-STAT signaling was suppressed in the BMR in comparison to the mouse. Interestingly, our experimental results showed upregulated Jak1/2 expressions in BMR fibroblasts during the replicative senescence process. The transcriptomic analysis using publicly available data also demonstrated that various cytokines related to JAK-STAT signaling were upregulated in the late passage cells, while some other cytokines such as MMPs and SERPINs were downregulated, representing a possible balance of senescence-associated secretory phenotypes (SASPs) in the BMR. Finally, our proteomics data also confirmed cytokine-mediated signaling activation in senescent BMR fibroblasts. Together, our findings suggest the critical role of JAK-STAT and cytokine-mediated signaling pathways during cellular senescence, pointing to the possible contribution of divergent inflammatory factors to the superior resistance of aging and cancer in BMRs.