Mol. Cells 2016; 39(9): 680-686
Published online September 20, 2016
https://doi.org/10.14348/molcells.2016.0125
© The Korean Society for Molecular and Cellular Biology
Correspondence to : *Correspondence: renocho@chosun.ac.kr
Uncoupling proteins (UCPs) are mitochondrial inner membrane proteins that function to dissipate proton motive force and mitochondrial membrane potential. One UCP has been identified in
Keywords
Uncoupling proteins (UCPs) are a small family of mitochondrial carrier proteins with five identified members in mammalian systems. The first discovered UCP1 was localized in brown adipose tissue and was shown to dissipate the proton gradient, which generated heat through uncoupling of oxidative phosphorylation from the electron transport chain (Nicholls and Locke, 1984). Several studies suggest that UCPs might be involved in many metabolic functions, including fatty acid transport, regulation of insulin secretion, and regulation of mitochondrial superoxide generation (Echtay, 2007). UCP2 was suggested to be a negative regulator of insulin secretion and acted through a mild uncoupling mechanism (Chan et al., 1999). Moreover, UCP2 and UCP3 are activated by superoxide from the mitochondrial inner membrane (Echtay et al., 2002; Talbot et al., 2004). It was proposed that UCPs could reduce mitochondrial reactive oxygen species (ROS) generation, and therefore attenuate damage derived from these molecules (Murphy et al., 2003). In a recent study, endothelial UCP2 was shown to function mainly in the control ROS generation in mitochondria during hyperglycemia (Koziel et al., 2015). Moreover, the recently identified UCP4 and UCP5 were specifically localized in the brain, and their roles were suggested to be in the modulation of energy production and mitochondrial ROS levels (Mao et al., 1999; Sanchis et al., 1998; Yu et al., 2000). Ectopic expression of these proteins resulted in lower mitochondrial membrane potential (ψm) and ROS content. It was proposed that high ψm is strongly correlated with increases in ROS in mitochondria, and consequently mitochondrial oxidative damage (Boveris et al., 1972; Echtay, 2007; Erlanson-Albertsson, 2003). It was indeed demonstrated that 4-hydroxynonenal (HNE), derived from lipid peroxidation, reduced mitochondrial ROS production, through uncoupling, and decreased ψm (Echtay and Brand, 2007; Echtay et al., 2003).
Under restricted diet conditions, UCP2, 4, and 5 levels were shown to increase, which was associated with decreased ROS production and reduced neurodegeneration in models of Parkinson’s disease (Duan and Mattson, 1999; Echtay, 2007; Sullivan et al., 2004). It has been suggested that UCPs regulate pathways involved in neurodegeneration, and protect against neurodegenerative diseases and aging through controlling ROS-induced oxidative stress. In addition, it was reported that
Surprisingly there are few studies on UCP in
Wild type Bristol N2 strain,
To clone the
For RNAi bacterial feeding constructs,
MitoTracker Red CMXRos (Invitrogen, Life Technologies Corporation, USA) was prepared following the manufacturer’s protocol and added to the growth media plate at a final concentration of 2 μg/ml. The worms were transferred to the media and incubation proceeded for 16 h.
Tetramethylrhodamine (TMRE, Invitrogen) is a cell-permeable and cationic fluorescent dye that is an indicator of mitochondrial membrane potential (ψm) (Farkas et al., 1989; Loew et al., 1993; Yoneda et al., 2004). TMRE in DMSO (50 μM) was applied to the worm plates at a final concentration of 0.1 μM. Worms were incubated on TMRE plates for 16 h and then prepared for observation after washing with M9 buffer (Yoneda et al., 2004). For ectopic overexpression experiments, heat shock was performed for 2 h at 30°C, 12 h before observation.
We scored an individual adult worm as one neuronal defect when it displayed at least one defect such as an outgrowth in the anterior lateral microtubule cells (ALM) or branching, blebbing, and waving in the posterior lateral microtubule cells (PLM) (Cho et al., 2015). All observations were conducted using a fluorescent microscope (80i-DS-Fi1, Nikon). For assessing neuronal defects, animals with ectopic overexpression of target proteins were subjected to a mild heat shock at 25°C for 2 h every 24 h.
A previous study reported that
It has been suggested that increased mitochondrial membrane potential (ψm) is positively associated with reactive oxygen species (ROS) generation in the mitochondria (Hansford et al., 1997; Korshunov et al., 1997; Votyakova and Reynolds, 2001). Moreover, UCPs dissipate the mitochondrial proton gradient, resulting in decreased ψm (Korshunov et al., 1997). To determine if UCP-4 is involved in regulating ψm, we used TMRE staining to visualize ψm in wild type,
Increased ROS, probably in the context of oxidative damage, is correlated with neuronal diseases such as Parkinson’s and Alzheimer’s (Fahn and Cohen, 1992; Lin and Beal, 2006). Human UCP2 was shown to protect neurons against oxidative stress (Mattiasson and Sullivan, 2006). We therefore examined if UCP-4 is involved in neuronal defects during the aging process. In recent reports, mechanosensory touch receptor neurons, anterior lateral microtubule cells (ALM) and posterior lateral microtubule cells (PLM), showed neuronal degenerations during aging, which included soma outgrowth, axon blebbing, and wavy processes (Pan et al., 2011; Tank et al., 2011; Toth et al., 2012). In addition, ALM and PLM cells are well-studied and easily observed (Chen et al., 2013). Therefore, We used the
To understand
For PLMs, neuronal defects gradually increased with aging in control and
According to the free radical theory, ROS might cause aging and aging-related disease (Harman, 1972). Mild uncoupling by UCPs resulting in lowered ROS levels can alleviate aging and aging-associated diseases such as Parkinson’s and Alzheimer’s disease that are driven by oxidative damage. However, this has not yet been clearly proven (Beckman and Ames, 1998; Divakaruni and Brand, 2011). The quantification of a mild uncoupling effect requires the development of specific methods to measure physiological ROS content, especially in native conditions (Divakaruni and Brand, 2011). Despite technical difficulty, the application of mild uncoupling has shown beneficial results. For example, mice expressing muscle-specific UCP1 showed decreased adiposity, increased metabolic rate, and diminished age-related diseases (Gates et al., 2007).
Increased ROS can cause oxidative damage, especially in the mitochondria (Harman, 1956). However, an increase in ROS can be beneficial for innate immunity as a major defense system against pathogens (Arsenijevic et al., 2000; Basu Ball et al., 2011). Moreover, in
This increased ψm could be related to pathogen resistance; we therefore assayed worm survival. We placed animals on pathogen-seeded plates during each developmental stage, specifically egg, L1?2, L3?4, and adult day 1, 5, and 10. After the worms were transferred, surviving animals were counted each day until all were dead. We used the OASIS program to calculate mean survival days based on the raw data (Yang et al., 2011). As seen in Fig. 4E, the
Considering the increase in ψm in wild type animals upon pathogen exposure, the resulting increase in ROS could serve to initiate an immune response. However, the
Alternatively, high levels of ROS can cause oxidative damage. It was observed that various organisms accumulated oxidative damage of macromolecules such as DNA, proteins, and lipids during aging (Back et al., 2012; Harman, 1956; 1972; 2009; Sohal and Weindruch, 1996). When
Mol. Cells 2016; 39(9): 680-686
Published online September 30, 2016 https://doi.org/10.14348/molcells.2016.0125
Copyright © The Korean Society for Molecular and Cellular Biology.
Injeong Cho1,2, Gyu Jin Hwang1,2, and Jeong Hoon Cho1,*
1Department of Biology Education, College of Education, Chosun University, Gwangju 61452, Korea, 2These authors contributed equally to this work
Correspondence to:*Correspondence: renocho@chosun.ac.kr
Uncoupling proteins (UCPs) are mitochondrial inner membrane proteins that function to dissipate proton motive force and mitochondrial membrane potential. One UCP has been identified in
Keywords:
Uncoupling proteins (UCPs) are a small family of mitochondrial carrier proteins with five identified members in mammalian systems. The first discovered UCP1 was localized in brown adipose tissue and was shown to dissipate the proton gradient, which generated heat through uncoupling of oxidative phosphorylation from the electron transport chain (Nicholls and Locke, 1984). Several studies suggest that UCPs might be involved in many metabolic functions, including fatty acid transport, regulation of insulin secretion, and regulation of mitochondrial superoxide generation (Echtay, 2007). UCP2 was suggested to be a negative regulator of insulin secretion and acted through a mild uncoupling mechanism (Chan et al., 1999). Moreover, UCP2 and UCP3 are activated by superoxide from the mitochondrial inner membrane (Echtay et al., 2002; Talbot et al., 2004). It was proposed that UCPs could reduce mitochondrial reactive oxygen species (ROS) generation, and therefore attenuate damage derived from these molecules (Murphy et al., 2003). In a recent study, endothelial UCP2 was shown to function mainly in the control ROS generation in mitochondria during hyperglycemia (Koziel et al., 2015). Moreover, the recently identified UCP4 and UCP5 were specifically localized in the brain, and their roles were suggested to be in the modulation of energy production and mitochondrial ROS levels (Mao et al., 1999; Sanchis et al., 1998; Yu et al., 2000). Ectopic expression of these proteins resulted in lower mitochondrial membrane potential (ψm) and ROS content. It was proposed that high ψm is strongly correlated with increases in ROS in mitochondria, and consequently mitochondrial oxidative damage (Boveris et al., 1972; Echtay, 2007; Erlanson-Albertsson, 2003). It was indeed demonstrated that 4-hydroxynonenal (HNE), derived from lipid peroxidation, reduced mitochondrial ROS production, through uncoupling, and decreased ψm (Echtay and Brand, 2007; Echtay et al., 2003).
Under restricted diet conditions, UCP2, 4, and 5 levels were shown to increase, which was associated with decreased ROS production and reduced neurodegeneration in models of Parkinson’s disease (Duan and Mattson, 1999; Echtay, 2007; Sullivan et al., 2004). It has been suggested that UCPs regulate pathways involved in neurodegeneration, and protect against neurodegenerative diseases and aging through controlling ROS-induced oxidative stress. In addition, it was reported that
Surprisingly there are few studies on UCP in
Wild type Bristol N2 strain,
To clone the
For RNAi bacterial feeding constructs,
MitoTracker Red CMXRos (Invitrogen, Life Technologies Corporation, USA) was prepared following the manufacturer’s protocol and added to the growth media plate at a final concentration of 2 μg/ml. The worms were transferred to the media and incubation proceeded for 16 h.
Tetramethylrhodamine (TMRE, Invitrogen) is a cell-permeable and cationic fluorescent dye that is an indicator of mitochondrial membrane potential (ψm) (Farkas et al., 1989; Loew et al., 1993; Yoneda et al., 2004). TMRE in DMSO (50 μM) was applied to the worm plates at a final concentration of 0.1 μM. Worms were incubated on TMRE plates for 16 h and then prepared for observation after washing with M9 buffer (Yoneda et al., 2004). For ectopic overexpression experiments, heat shock was performed for 2 h at 30°C, 12 h before observation.
We scored an individual adult worm as one neuronal defect when it displayed at least one defect such as an outgrowth in the anterior lateral microtubule cells (ALM) or branching, blebbing, and waving in the posterior lateral microtubule cells (PLM) (Cho et al., 2015). All observations were conducted using a fluorescent microscope (80i-DS-Fi1, Nikon). For assessing neuronal defects, animals with ectopic overexpression of target proteins were subjected to a mild heat shock at 25°C for 2 h every 24 h.
A previous study reported that
It has been suggested that increased mitochondrial membrane potential (ψm) is positively associated with reactive oxygen species (ROS) generation in the mitochondria (Hansford et al., 1997; Korshunov et al., 1997; Votyakova and Reynolds, 2001). Moreover, UCPs dissipate the mitochondrial proton gradient, resulting in decreased ψm (Korshunov et al., 1997). To determine if UCP-4 is involved in regulating ψm, we used TMRE staining to visualize ψm in wild type,
Increased ROS, probably in the context of oxidative damage, is correlated with neuronal diseases such as Parkinson’s and Alzheimer’s (Fahn and Cohen, 1992; Lin and Beal, 2006). Human UCP2 was shown to protect neurons against oxidative stress (Mattiasson and Sullivan, 2006). We therefore examined if UCP-4 is involved in neuronal defects during the aging process. In recent reports, mechanosensory touch receptor neurons, anterior lateral microtubule cells (ALM) and posterior lateral microtubule cells (PLM), showed neuronal degenerations during aging, which included soma outgrowth, axon blebbing, and wavy processes (Pan et al., 2011; Tank et al., 2011; Toth et al., 2012). In addition, ALM and PLM cells are well-studied and easily observed (Chen et al., 2013). Therefore, We used the
To understand
For PLMs, neuronal defects gradually increased with aging in control and
According to the free radical theory, ROS might cause aging and aging-related disease (Harman, 1972). Mild uncoupling by UCPs resulting in lowered ROS levels can alleviate aging and aging-associated diseases such as Parkinson’s and Alzheimer’s disease that are driven by oxidative damage. However, this has not yet been clearly proven (Beckman and Ames, 1998; Divakaruni and Brand, 2011). The quantification of a mild uncoupling effect requires the development of specific methods to measure physiological ROS content, especially in native conditions (Divakaruni and Brand, 2011). Despite technical difficulty, the application of mild uncoupling has shown beneficial results. For example, mice expressing muscle-specific UCP1 showed decreased adiposity, increased metabolic rate, and diminished age-related diseases (Gates et al., 2007).
Increased ROS can cause oxidative damage, especially in the mitochondria (Harman, 1956). However, an increase in ROS can be beneficial for innate immunity as a major defense system against pathogens (Arsenijevic et al., 2000; Basu Ball et al., 2011). Moreover, in
This increased ψm could be related to pathogen resistance; we therefore assayed worm survival. We placed animals on pathogen-seeded plates during each developmental stage, specifically egg, L1?2, L3?4, and adult day 1, 5, and 10. After the worms were transferred, surviving animals were counted each day until all were dead. We used the OASIS program to calculate mean survival days based on the raw data (Yang et al., 2011). As seen in Fig. 4E, the
Considering the increase in ψm in wild type animals upon pathogen exposure, the resulting increase in ROS could serve to initiate an immune response. However, the
Alternatively, high levels of ROS can cause oxidative damage. It was observed that various organisms accumulated oxidative damage of macromolecules such as DNA, proteins, and lipids during aging (Back et al., 2012; Harman, 1956; 1972; 2009; Sohal and Weindruch, 1996). When