1.
Unravelling the relationship between macroautophagy and mitochondrial ROS in cancer therapy.
Zhao, Y, Qu, T, Wang, P, Li, X, Qiang, J, Xia, Z, Duan, H, Huang, J, Zhu, L
Apoptosis : an international journal on programmed cell death. 2016;(5):517-31
Abstract
Macroautophagy (Autophagy), an evolutionarily conserved cellular self-digesting process implicated in various physiological and pathological processes, is activated by different stimuli including oxidative stress. Reactive oxygen species (ROS) are involved in autophagy modulation through multiple signaling pathways and transcription regulators. Accumulating data support both a positive and negative role of ROS-modulated autophagy in cancer. As a tumor suppressive mechanism, autophagy induces autophagic cell death and maintains genome stability. Conversely, autophagy may promote cancer development by limiting metabolic stress and supplying high-energetic nutrients. Mitochondrial ROS (mitoROS), the main source of endogenous ROS, serve as essential signal transducers that mediate autophagy, while autophagy can also regulate mitochondrial ROS generation in turn. Here, we untangle the knot between mitochondrial ROS and autophagy, which may be of great significance to solve the conundrum of the inter-conversion between cytoprotective and cytotoxic roles of autophagy; thus providing new insights for current cancer therapies. Whilst, we focus on anti-tumor agents that target mitoROS-regulated autophagy, in the hope of fueling the exploration of more potential novel anti-cancer drugs in the future.
2.
Oxidative post-translational modifications of cysteine residues in plant signal transduction.
Waszczak, C, Akter, S, Jacques, S, Huang, J, Messens, J, Van Breusegem, F
Journal of experimental botany. 2015;(10):2923-34
Abstract
In plants, fluctuation of the redox balance by altered levels of reactive oxygen species (ROS) can affect many aspects of cellular physiology. ROS homeostasis is governed by a diversified set of antioxidant systems. Perturbation of this homeostasis leads to transient or permanent changes in the redox status and is exploited by plants in different stress signalling mechanisms. Understanding how plants sense ROS and transduce these stimuli into downstream biological responses is still a major challenge. ROS can provoke reversible and irreversible modifications to proteins that act in diverse signalling pathways. These oxidative post-translational modifications (Ox-PTMs) lead to oxidative damage and/or trigger structural alterations in these target proteins. Characterization of the effect of individual Ox-PTMs on individual proteins is the key to a better understanding of how cells interpret the oxidative signals that arise from developmental cues and stress conditions. This review focuses on ROS-mediated Ox-PTMs on cysteine (Cys) residues. The Cys side chain, with its high nucleophilic capacity, appears to be the principle target of ROS. Ox-PTMs on Cys residues participate in various signalling cascades initiated by plant stress hormones. We review the mechanistic aspects and functional consequences of Cys Ox-PTMs on specific target proteins in view of stress signalling events.