Molecular Biology and Genetics / Moleküler Biyoloji ve Genetik
Permanent URI for this collectionhttps://hdl.handle.net/11147/9
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Article Citation - WoS: 90Citation - Scopus: 94Progesterone and Wnt4 Control Mammary Stem Cells Via Myoepithelial Crosstalk(John Wiley and Sons Inc., 2015) Rajaram, Renuga Devi; Buric, Duje; Caikovski, Marian; Ayyanan, Ayyakkannu; Rougemont, Jacques; Shan, Jingdong; Vainio, Seppo J.; Yalçın Özuysal, Özden; Brisken, CathrinOvarian hormones increase breast cancer risk by poorly understood mechanisms. We assess the role of progesterone on global stem cell function by serially transplanting mouse mammary epithelia. Progesterone receptor (PR) deletion severely reduces the regeneration capacity of the mammary epithelium. The PR target, receptor activator of Nf-κB ligand (RANKL), is not required for this function, and the deletion of Wnt4 reduces the mammary regeneration capacity even more than PR ablation. A fluorescent reporter reveals so far undetected perinatal Wnt4 expression that is independent of hormone signaling. Pubertal and adult Wnt4 expression is specific to PR+ luminal cells and requires intact PR signaling. Conditional deletion of Wnt4 reveals that this early, previously unappreciated, Wnt4 expression is functionally important. We provide genetic evidence that canonical Wnt signaling in the myoepithelium required PR and Wnt4, whereas the canonical Wnt signaling activities observed in the embryonic mammary bud and in the stroma around terminal end buds are independent of Wnt4. Thus, progesterone and Wnt4 control stem cell function through a luminal-myoepithelial crosstalk with Wnt4 acting independent of PR perinatally. Synopsis This paper ascribes a new role for Wnt4 in pre-pubertal mammary gland development while revealing luminal cells to respond to Wnt activation. During regeneration, Wnt4 interacts with progesterone receptor signaling, correcting previous notions on RANKL signaling in this context. Wnt4 is an essential control factor for mammary epithelial stem cell function. RANKL is not required for mammary gland regeneration potential. Wnt4 activates canonical Wnt signaling in the basal/myoepithelial compartment. Progesterone receptor signaling is required for mammary epithelial Wnt4 expression already during puberty. This paper ascribes a new role for Wnt4 in pre-pubertal mammary gland development while revealing luminal cells to respond to Wnt activation. During regeneration, Wnt4 interacts with progesterone receptor signaling, correcting previous notions on RANKL signaling in this context.Article Citation - WoS: 32Citation - Scopus: 34Therapeutic Applications of Bioactive Sphingolipids in Hematological Malignancies(John Wiley and Sons Inc., 2010) Ekiz, Hüseyin Atakan; Baran, YusufSphingolipids are sphingosine-based lipid molecules that have important functions in cellular signal transduction and in a variety of cellular processes including proliferation, differentiation, programmed cell death (apoptosis) and responses to stressful conditions. Ceramides, dihydroceramide, sphingosine and sphingosine-1-phosphate are examples of those bioactive sphingolipids. They have a major impact on determination of the cell fate by contributing to the cell survival or cell death through apoptosis. Despite the number of carbon atoms in the fatty acid chain changes the physiological role; ceramides generally exert suppressive roles on the cell proliferation. There have been several enzymes identified in this pathway that are responsible for the conversion of ceramide into other sphingolipid derivatives. Those derivatives also have differential roles on those cellular processes. Sphingosine-1-phosphate is an example of such sphingolipid derivatives which has antiapoptotic effects. As they have significant impacts particularly on the cell death and survival, bioactive sphingolipids have a great potential to be targets in cancer therapy. Increasing number of studies indicates that sphingolipid derivatives are important in the progression of hematological malignancies, and they are also involved in the resistance to current chemotherapeutic options. This review compiles the current knowledge in this area for enlightening the therapeutic potentials of bioactive sphingolipids in various leukemias. © 2010 UICC.Article Citation - WoS: 29Citation - Scopus: 29Methionine Sulfoxide Reduction and the Aging Process(John Wiley and Sons Inc., 2007) Koç, Ahmet; Gladyshev, Vadim N.Aging has been described for multicellular and asymmetrically dividing organisms, but the mechanisms are poorly understood. Oxidation of proteins is considered to be one of the major factors that leads to aging. Oxidative damage to proteins results in the oxidation of certain amino acid residues, among which oxidation of sulfur-containing amino acids, methionine and cysteine, is notable because of the susceptibility of these residues to damage, and occurrence of repair mechanisms. Methionine sulfoxide reductases, MsrA and MsrB, are thioredoxin-dependent oxidoreductases that reduce oxidized forms of methionine, methionine sulfoxides, in a stereospecific manner. These enzymes are present in all cell types and have shown to be regulating life spans in mammals, insects, and yeast. Here, their roles in modulating yeast life span are discussed.Article Citation - WoS: 59Citation - Scopus: 60Effects of Deleting Mitochondrial Antioxidant Genes on Life Span(John Wiley and Sons Inc., 2007) Ünlü, Ercan Selçuk; Koç, AhmetReactive oxygen species (ROS) damage biomolecules, accelerate aging, and shorten life span, whereas antioxidant enzymes mitigate these effects. Because mitochondria are a primary site of ROS generation and also a primary target of ROS attack, they have become a major focus area of aging studies. Here, we employed yeast genetics to identify mitochondrial antioxidant genes that are important for replicative life span. In our studies, it was found that among the known mitochondrial antioxidant genes (TTR1, CCD1, SOD1, GLO4, TRR2, TRX3, CCS1, SOD2, GRX5, PRX1), deletion of only three genes, SOD1 (Cu, Zn superoxide dismutase), SOD2 (Manganese-containing superoxide dismutase), and CCS1 (Copper chaperone), shortened the life span enormously. The life span decreased 40% for Δsod1 mutant, 72% for Δsod2 mutant, and 50% for Δccs1 mutant. Deletion of the other genes had little or no effect on life span.Letter Citation - WoS: 2Citation - Scopus: 3Rates of Myocardial Infarction and Coronary Artery Disease and Risk Factors in Patients Treated With Radiation Therapy for Early-Stage Breast Cancer(John Wiley and Sons Inc., 2007) Ural, Ali Uğur; Avcu, Ferit; Baran, YusufWe read the interesting article by Jagsi et al on the increased rates of coronary artery disease in patients treated with radiation therapy for early-stage breast cancer.1 In their study, those authors concluded that the findings support further assessment of clinical outcomes when newer techniques of chemotherapy planning are employed as well as investigation of the potential role of innovative techniques. However, there was no mention of the novel radiosensitizing and chemosensitizing effects of bisphosphonates (BPs), which inhibit tumor cell adhesion to bone, and tumor growth in breast cancer.