- Email: [email protected]
Control of AQP8-dependent H2O2 transport across the plasma membrane: Implications for cell signaling
M. Casal / Free Radical Biology and Medicine 120 (2018) S6–S23
L-3
Control of AQP8-dependent H2O2 transport across the plasma membrane: Implications for cell signaling
E-mail address: [email protected]
http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.033
Stefano Bestetti 1, Iria Medraño-Fernandez 1, Gerd P. Bienert 2, Mauro Galli 1, Michela Ghitti 1, Giovanna Musco 1, Andrea Orsi 1, Anna Rubartelli 1, Roberto Sitia 1
L-5
1
Ferroptosis: Death by lipid peroxidation
Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele and Università Vita-Salute, Milan, Italy 2 Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
S7
Brent R. Stockwell Columbia University, New York, USA
Triggering of tyrosine kinase receptors activates NADPH-oxidases (NOX) to release H2O2 in the outer leaflet of the plasma membrane. To efficiently reach its cytosolic targets and amplify signaling, H2O2 requires aquaporin-8 (AQP8) or other proteinaceous channels endowed with peroxiporin activity. Particularly during stress conditions, cells can regulate the transport of H2O2 as well as H2O through AQP8. Besides limiting the risks of excessive oxidation, reversible gating of AQP8 modulates signal strength and duration. Channel gating is achieved through a two-step mechanism, in which sulphenylation of a conserved cysteine (C53) in the mouth of the AQP8 channel precedes its persulfidation. Cystathionine-βsynthase (CBS) activity is essential for channel blockade and addition of exogenous H2S restores inhibition. Thus, CBS is the main source of H2S that gates AQP8. Based on molecular modeling and mutagenesis experiments, we propose a mechanism explaining how cells tune H2O2transport to control signaling and limit oxidative stress.
E-mail address: [email protected]
In 2012, my lab reported that a novel small molecule named erastin activates a form of non-apoptotic cell death that we termed ferroptosis. My lab members and I found that erastin inhibits system xc-, depleting cells of cysteine and glutathione. Subsequently, we discovered that another novel compound, RSL3, directly inhibits glutathione peroxidase 4 to cause the same phenotype of cell death. More recently, we have identified two additional mechanisms for triggering ferroptosis, and several genetic and pharmacological means of inhibiting this form of cell death. We have also found evidence that ferroptosis is involved in numerous degenerative diseases and can be exploited to target some cancers. Finally, recent work in my lab suggests a hypothesis for how ferroptotic cell death is executed.
E-mail address: [email protected]
http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.034
Acknowledgements Supported by AIRC and Cariplo
http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.032
L-4
L-6
Molecular underpinnings controlling ferroptotic cell death Marcus Conrad
Role of NOX-generated reactive oxygen species in health and disease
Helmholtz Zentrum Munich, Germany
Karl-Heinz Krause University of Geneva, Switzerland
NOX enzymes are reactive oxygen (ROS)- producing NADPH oxidases, which are found in most eukaryotic organisms and fulfill a large spectrum of physiological functions. Most mammals have 7 genes coding for NOX enzymes with different expression patterns and different activation mechanisms. The most relevant physiological functions of NOX enzymes cluster around host defense, biosynthetic processes (e.g. thyroid hormone synthesis, crosslinking of extracellular matrix), and cellular signaling (e.g. reversible inactivation of protein phosphatases). Thus, generation of ROS is not a pathological process in itself, however excessive ROS generation through overshooting and inappropriate NOX activation may contribute to pathophysiology. NOX enzymes have been implicated in the pathophysiology of i) fibrotic disease; ii) vascular disease; iii) neurodegenerative disease; iv) cancer; v) sensory impairment (note that this list is incomplete). I will give examples of involvement of NOX enzymes in different disease processes, outline underlying pathomechanisms, and discuss the path towards therapeutic applications.
Ferroptosis is a pharmacologically amenable form of regulated necrosis and marked by iron-dependent lipid peroxidation and metabolic constraints. Ferroptosis is involved in various disease contexts including cancer, ischemia/ reperfusion injury and neurodegeneration. Due to its unique role in quenching phospholipid hydroperoxides, selenium-containing glutathione peroxidase 4 (GPX4) is considered as the key ferroptosis regulator. Genome-wide genetic screening efforts have recently identified ACSL4 as an additional and essential player in the ferroptotic death process. Despite the outstanding role for GPX4 in ferroptosis, little is known about the molecular details that regulate GPX4 function and stability. Therefore, a novel mouse line expressing a hypomorphic GPX4 allele was established. Using this model, we now show that a specific type of interneurons requires selenium in the active site of GPX4, which emerges to be the limiting factor for mammalian life. Moreover, selenium utilization by GPX4 appears to have evolved as prerequisite to prevent peroxide-induced GPX4 enzyme overoxidation, thereby protecting against ferroptosis. Current studies focus on how partially reduced forms of oxygen trigger the ferroptotic process in different disease contexts.
E-mail address: [email protected]
http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.035
L-3
Control of AQP8-dependent H2O2 transport across the plasma membrane: Implications for cell signaling
E-mail address: [email protected]
http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.033
Stefano Bestetti 1, Iria Medraño-Fernandez 1, Gerd P. Bienert 2, Mauro Galli 1, Michela Ghitti 1, Giovanna Musco 1, Andrea Orsi 1, Anna Rubartelli 1, Roberto Sitia 1
L-5
1
Ferroptosis: Death by lipid peroxidation
Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele and Università Vita-Salute, Milan, Italy 2 Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
S7
Brent R. Stockwell Columbia University, New York, USA
Triggering of tyrosine kinase receptors activates NADPH-oxidases (NOX) to release H2O2 in the outer leaflet of the plasma membrane. To efficiently reach its cytosolic targets and amplify signaling, H2O2 requires aquaporin-8 (AQP8) or other proteinaceous channels endowed with peroxiporin activity. Particularly during stress conditions, cells can regulate the transport of H2O2 as well as H2O through AQP8. Besides limiting the risks of excessive oxidation, reversible gating of AQP8 modulates signal strength and duration. Channel gating is achieved through a two-step mechanism, in which sulphenylation of a conserved cysteine (C53) in the mouth of the AQP8 channel precedes its persulfidation. Cystathionine-βsynthase (CBS) activity is essential for channel blockade and addition of exogenous H2S restores inhibition. Thus, CBS is the main source of H2S that gates AQP8. Based on molecular modeling and mutagenesis experiments, we propose a mechanism explaining how cells tune H2O2transport to control signaling and limit oxidative stress.
E-mail address: [email protected]
In 2012, my lab reported that a novel small molecule named erastin activates a form of non-apoptotic cell death that we termed ferroptosis. My lab members and I found that erastin inhibits system xc-, depleting cells of cysteine and glutathione. Subsequently, we discovered that another novel compound, RSL3, directly inhibits glutathione peroxidase 4 to cause the same phenotype of cell death. More recently, we have identified two additional mechanisms for triggering ferroptosis, and several genetic and pharmacological means of inhibiting this form of cell death. We have also found evidence that ferroptosis is involved in numerous degenerative diseases and can be exploited to target some cancers. Finally, recent work in my lab suggests a hypothesis for how ferroptotic cell death is executed.
E-mail address: [email protected]
http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.034
Acknowledgements Supported by AIRC and Cariplo
http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.032
L-4
L-6
Molecular underpinnings controlling ferroptotic cell death Marcus Conrad
Role of NOX-generated reactive oxygen species in health and disease
Helmholtz Zentrum Munich, Germany
Karl-Heinz Krause University of Geneva, Switzerland
NOX enzymes are reactive oxygen (ROS)- producing NADPH oxidases, which are found in most eukaryotic organisms and fulfill a large spectrum of physiological functions. Most mammals have 7 genes coding for NOX enzymes with different expression patterns and different activation mechanisms. The most relevant physiological functions of NOX enzymes cluster around host defense, biosynthetic processes (e.g. thyroid hormone synthesis, crosslinking of extracellular matrix), and cellular signaling (e.g. reversible inactivation of protein phosphatases). Thus, generation of ROS is not a pathological process in itself, however excessive ROS generation through overshooting and inappropriate NOX activation may contribute to pathophysiology. NOX enzymes have been implicated in the pathophysiology of i) fibrotic disease; ii) vascular disease; iii) neurodegenerative disease; iv) cancer; v) sensory impairment (note that this list is incomplete). I will give examples of involvement of NOX enzymes in different disease processes, outline underlying pathomechanisms, and discuss the path towards therapeutic applications.
Ferroptosis is a pharmacologically amenable form of regulated necrosis and marked by iron-dependent lipid peroxidation and metabolic constraints. Ferroptosis is involved in various disease contexts including cancer, ischemia/ reperfusion injury and neurodegeneration. Due to its unique role in quenching phospholipid hydroperoxides, selenium-containing glutathione peroxidase 4 (GPX4) is considered as the key ferroptosis regulator. Genome-wide genetic screening efforts have recently identified ACSL4 as an additional and essential player in the ferroptotic death process. Despite the outstanding role for GPX4 in ferroptosis, little is known about the molecular details that regulate GPX4 function and stability. Therefore, a novel mouse line expressing a hypomorphic GPX4 allele was established. Using this model, we now show that a specific type of interneurons requires selenium in the active site of GPX4, which emerges to be the limiting factor for mammalian life. Moreover, selenium utilization by GPX4 appears to have evolved as prerequisite to prevent peroxide-induced GPX4 enzyme overoxidation, thereby protecting against ferroptosis. Current studies focus on how partially reduced forms of oxygen trigger the ferroptotic process in different disease contexts.
E-mail address: [email protected]
http://dx.doi.org/10.1016/j.freeradbiomed.2018.04.035