- Email: [email protected]
Impact of peroxynitrite-mediated nitrosative stress on human sperm cells
S54
A. Stepanova et al. / Free Radical Biology and Medicine 120 (2018) S45–S166
mitochondria. While it is now clear that recovery respiration is essential for tumour formation, its functional link to the process is unclear. It includes gradual increase in mtDNA level of homoplasmic host polymorphism, followed by binding of mtDNA-processing enzymes to its regulatory domain, replication and transcription of mtDNA, increased expression of components of respiratory complexes, resulting in full restoration of respiration. We found that pyrimidine biosynthesis, supported by the respiration-linked enzyme dihydroorotate dehydrogenase (DHODH), is critically required to overcome cell cycle arrest. We further confirmed that efficient de novo pyrimidine synthesis, necessary for tumour cell proliferation, is the key event for triggering tumour growth. Moreover, respiration recovery, which is necessary for tumour formation, is associated with efficient de novo pyrimidine synthesis. In conclusion, we propose that DHODH is a critical link between de novo pyrimidine synthesis and respiration, and that it is a promising target for broad-spectrum cancer therapy.
E-mail address: l.dong@griffith.edu.au http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.177
lead to the appearance of biochemical markers of cell death compatible with MPT-driven necrosis
E-mail address: [email protected] http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.178
P-32
The tumor environment stabilizes c-Myc oncoprotein through its sustained phosphorylation at serine 62, which promotes its oncogenic activity Deepika Raman 1, Shazib Pervaiz 1,2,3 1
National University of Singapore, Singapore National University Cancer Institute, Singapore 3 NUS Graduate School for Integrative Sciences and Engineering, Singapore 2
P-31
Impact of peroxynitrite-mediated nitrosative stress on human sperm cells Pamela Uribe 1,2, Juana V. Villegas 2,3, María E. Cabrillana 4,5, Rodrigo Boguen 3, Raúl Sánchez 1,6, Miguel W. Fornés 4,5, Vladimir Isachenko 7, Evgenia Isachenko 7 1
Center of Excellence in Translational Medicine, Universidad de La Frontera, Temuco, Chile 2 Department of Internal Medicine, Faculty of Medicine, Universidad de La Frontera, Temuco, Chile 3 Center of Reproductive Biotechnology - Scientific and Technological Bioresource Nucleus (CEBIOR – BIOREN), Universidad de La Frontera, Temuco, Chile 4 Laboratory of Andrology Research of Mendoza (LIAM) Institute of Histology and Embriology of Mendoza (IHEM) Histology and Embryology Area, Department of Morphology and Physiology, School of Medicine, National University of Cuyo & CCT-Mendoza, CONICET, Mendoza, Argentina 5 Research Institute (CIUDA), Medicine Faculty, Universidad del Aconcagua. Mendoza, Argentina 6 Department of Preclinical Sciences, Faculty of Medicine, Universidad de La Frontera, Temuco, Chile 7 Research Group for Reproductive Medicine, Cologne University, Cologne, Germany
We have previously demonstrated that redox homeostasis is governed by two key ROS – superoxide anion (O2-) and hydrogen peroxide (H2O2). Tilting the balance to O2- contributes to engaging cancers onto a prosurvival trajectory. Here, we present a singular event wherein redox modulation of c-Myc attributes cancer cells with survival advantages and elevates their chemoresistance potential. Phosphorylation of c-Myc correlates with its stabilization in cancers. While S62 phosphorylation increases c-Myc stability, T58 phosphorylation destabilizes it. Of particular interest is phosphatase PP2A, as we have shown that it is amenable to redox insults. We have now elucidated that B56α regulatory subunit of PP2A is amenable to redox modification preventing interaction of c-Myc bound B56α with PP2A-AC core enzyme. As assembly of PP2A holoenzyme is disrupted, c-Myc remains phosphorylated at S62. Hyperphosphorylated c-Myc cannot be recognized and engaged by the proteasome leading to increased protein stability and a moderate rise in activation of c-Myc targets. Thus, we have established a novel mechanism wherein the balance between O2-:H2O2 ratio stimulates a pro-survival milieu and reinforces chemoresistance through redox modification of PP2A-B56α, consequentially resulting in stabilization of c-Myc.
E-mail address: [email protected] http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.179
P-33 Nitrosative stress is caused by high levels of reactive nitrogen species (RNS) and among the most toxic RNS is peroxynitrite. In infertile men there is an association between high levels of peroxynitrite and decreased sperm quality; however, less is known about the specific cellular impairment caused by peroxynitrite in sperm cells. The aim here was to characterize the in vitro effect of peroxynitrite on human sperm. For this, spermatozoa were exposed to 3-morpholinosydnonimine, a compound that generates peroxynitrite, and several parameters of sperm quality and biochemical markers of cell death were assessed. Untreated sperm were included as controls. At early incubation times peroxynitrite exposure caused a decrease in mitochondrial membrane potential, ATP level and motility while thiol oxidation and tyrosine nitration increased. At prolonged incubation time viability decreased and DNA oxidation, DNA fragmentation and ultrastructural damage increased. Mitochondrial permeability transition (MPT) was induced while caspase activation and phosphatidylserine externalization were not evidenced. These results indicate that peroxynitrite exposure impairs sperm function and ultrastructure and
The comparison of vitamin E and vitamin C levels in type 2 diabetic patients under monotherapy Ayse C. Hamamcioglu 1, Zehra Safi-Oz 2, Yasin Hazer 3, Taner Bayraktaroglu 4 1
Biochemistry Department, Faculty of Pharmacy, Bulent Ecevit University, Zonguldak, Turkey 2 Medical Biology Department, Faculty of Medicine, Bulent Ecevit University, Zonguldak, Turkey 3 Pharmaceutical Botany Department, Faculty of Pharmacy, Bulent Ecevit University, Zonguldak, Turkey 4 Endocrinology and Metabolism Department, Faculty of Medicine, Bulent Ecevit University, Zonguldak, Turkey
A. Stepanova et al. / Free Radical Biology and Medicine 120 (2018) S45–S166
mitochondria. While it is now clear that recovery respiration is essential for tumour formation, its functional link to the process is unclear. It includes gradual increase in mtDNA level of homoplasmic host polymorphism, followed by binding of mtDNA-processing enzymes to its regulatory domain, replication and transcription of mtDNA, increased expression of components of respiratory complexes, resulting in full restoration of respiration. We found that pyrimidine biosynthesis, supported by the respiration-linked enzyme dihydroorotate dehydrogenase (DHODH), is critically required to overcome cell cycle arrest. We further confirmed that efficient de novo pyrimidine synthesis, necessary for tumour cell proliferation, is the key event for triggering tumour growth. Moreover, respiration recovery, which is necessary for tumour formation, is associated with efficient de novo pyrimidine synthesis. In conclusion, we propose that DHODH is a critical link between de novo pyrimidine synthesis and respiration, and that it is a promising target for broad-spectrum cancer therapy.
E-mail address: l.dong@griffith.edu.au http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.177
lead to the appearance of biochemical markers of cell death compatible with MPT-driven necrosis
E-mail address: [email protected] http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.178
P-32
The tumor environment stabilizes c-Myc oncoprotein through its sustained phosphorylation at serine 62, which promotes its oncogenic activity Deepika Raman 1, Shazib Pervaiz 1,2,3 1
National University of Singapore, Singapore National University Cancer Institute, Singapore 3 NUS Graduate School for Integrative Sciences and Engineering, Singapore 2
P-31
Impact of peroxynitrite-mediated nitrosative stress on human sperm cells Pamela Uribe 1,2, Juana V. Villegas 2,3, María E. Cabrillana 4,5, Rodrigo Boguen 3, Raúl Sánchez 1,6, Miguel W. Fornés 4,5, Vladimir Isachenko 7, Evgenia Isachenko 7 1
Center of Excellence in Translational Medicine, Universidad de La Frontera, Temuco, Chile 2 Department of Internal Medicine, Faculty of Medicine, Universidad de La Frontera, Temuco, Chile 3 Center of Reproductive Biotechnology - Scientific and Technological Bioresource Nucleus (CEBIOR – BIOREN), Universidad de La Frontera, Temuco, Chile 4 Laboratory of Andrology Research of Mendoza (LIAM) Institute of Histology and Embriology of Mendoza (IHEM) Histology and Embryology Area, Department of Morphology and Physiology, School of Medicine, National University of Cuyo & CCT-Mendoza, CONICET, Mendoza, Argentina 5 Research Institute (CIUDA), Medicine Faculty, Universidad del Aconcagua. Mendoza, Argentina 6 Department of Preclinical Sciences, Faculty of Medicine, Universidad de La Frontera, Temuco, Chile 7 Research Group for Reproductive Medicine, Cologne University, Cologne, Germany
We have previously demonstrated that redox homeostasis is governed by two key ROS – superoxide anion (O2-) and hydrogen peroxide (H2O2). Tilting the balance to O2- contributes to engaging cancers onto a prosurvival trajectory. Here, we present a singular event wherein redox modulation of c-Myc attributes cancer cells with survival advantages and elevates their chemoresistance potential. Phosphorylation of c-Myc correlates with its stabilization in cancers. While S62 phosphorylation increases c-Myc stability, T58 phosphorylation destabilizes it. Of particular interest is phosphatase PP2A, as we have shown that it is amenable to redox insults. We have now elucidated that B56α regulatory subunit of PP2A is amenable to redox modification preventing interaction of c-Myc bound B56α with PP2A-AC core enzyme. As assembly of PP2A holoenzyme is disrupted, c-Myc remains phosphorylated at S62. Hyperphosphorylated c-Myc cannot be recognized and engaged by the proteasome leading to increased protein stability and a moderate rise in activation of c-Myc targets. Thus, we have established a novel mechanism wherein the balance between O2-:H2O2 ratio stimulates a pro-survival milieu and reinforces chemoresistance through redox modification of PP2A-B56α, consequentially resulting in stabilization of c-Myc.
E-mail address: [email protected] http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.179
P-33 Nitrosative stress is caused by high levels of reactive nitrogen species (RNS) and among the most toxic RNS is peroxynitrite. In infertile men there is an association between high levels of peroxynitrite and decreased sperm quality; however, less is known about the specific cellular impairment caused by peroxynitrite in sperm cells. The aim here was to characterize the in vitro effect of peroxynitrite on human sperm. For this, spermatozoa were exposed to 3-morpholinosydnonimine, a compound that generates peroxynitrite, and several parameters of sperm quality and biochemical markers of cell death were assessed. Untreated sperm were included as controls. At early incubation times peroxynitrite exposure caused a decrease in mitochondrial membrane potential, ATP level and motility while thiol oxidation and tyrosine nitration increased. At prolonged incubation time viability decreased and DNA oxidation, DNA fragmentation and ultrastructural damage increased. Mitochondrial permeability transition (MPT) was induced while caspase activation and phosphatidylserine externalization were not evidenced. These results indicate that peroxynitrite exposure impairs sperm function and ultrastructure and
The comparison of vitamin E and vitamin C levels in type 2 diabetic patients under monotherapy Ayse C. Hamamcioglu 1, Zehra Safi-Oz 2, Yasin Hazer 3, Taner Bayraktaroglu 4 1
Biochemistry Department, Faculty of Pharmacy, Bulent Ecevit University, Zonguldak, Turkey 2 Medical Biology Department, Faculty of Medicine, Bulent Ecevit University, Zonguldak, Turkey 3 Pharmaceutical Botany Department, Faculty of Pharmacy, Bulent Ecevit University, Zonguldak, Turkey 4 Endocrinology and Metabolism Department, Faculty of Medicine, Bulent Ecevit University, Zonguldak, Turkey