Redox, a native modality in biology involving the flow of electrons, energy, and information, is used for energy-harvesting, biosynthesis, immune-defense, and signaling. Because electrons (in contrast Show more
Redox, a native modality in biology involving the flow of electrons, energy, and information, is used for energy-harvesting, biosynthesis, immune-defense, and signaling. Because electrons (in contrast to protons) are not soluble in the medium, electron-flow through the redox modality occurs through redox reactions that are sometimes organized into pathways and networks (e.g., redox interactomes). Redox is also accessible to electrochemistry, which enables electrodes to receive and transmit electrons to exchange energy and information with biology. In this Perspective, efforts to develop electrochemistry as a tool for redox-based bio-information processing: to interconvert redox-based molecular attributes into interpretable electronic signals, are described. Using a series of Case Studies, how the information-content of the measurements can be enriched using: diffusible mediators; tuned electrical input sequences; and cross-modal measurements (e.g., electrical plus spectral), is shown. Also, theory-guided feature engineering approaches to compress the information in the electronic signals into quantitative metrics (i.e., features) that can serve as correlating variables for pattern recognition by data-driven analysis are described. Finally, how redox provides a modality for electrogenetic actuation is illustrated. It is suggested that electrochemistry's capabilities to provide real-time, low-cost, and high-content data in an electronic format allow the feedback-control needed for autonomous learning and deployable sensing/actuation. Show less
Oxidative stress appears to act globally and span body systems (e.g., nervous, immune, and endocrine). Currently, there is no single, generally-accepted measurement of oxidative stress. Many possible Show more
Oxidative stress appears to act globally and span body systems (e.g., nervous, immune, and endocrine). Currently, there is no single, generally-accepted measurement of oxidative stress. Many possible measurement approaches focus on the bottom-up analysis of individual molecules (e.g., reactive species, antioxidants, hormones or signaling molecules) or combinations of molecules (e.g., proteomics or metabolomics). Efforts to develop a global measurement of oxidative stress often detect a sample's ability to reduce a metal-ion (e.g., iron or copper) or quench a free radical. Here, we review results from a recently-developed iridium-reducing capacity assay (Ir-RCA) and suggest that this method offers several key benefits as a potential measurement of oxidative stress. First, the Ir-RCA employs simple optical and/or electrochemical measurements that can be extended to high throughput formats. Second, the Ir-RCA appears to be more sensitive than alternative global antioxidant assays. Third, the Ir-RCA measures stable molecular features of a sample. Fourth, the Ir-RCA has been "validated" by showing statistically significant differences in persons diagnosed with schizophrenia (N = 73) versus healthy controls (N = 45). Fifth, the Ir-RCA measurement of oxidative stress is "movable": psychosocial stressors can increase this measure of oxidative stress, while beneficial dietary interventions can decrease this measure of oxidative stress. Limitations and future directions for the Ir-RCA are discussed. Show less
Abstract Imaging contrast agents are widely investigated in preclinical and clinical studies, among which biogenic imaging contrast agents (BICAs) are developing rapidly and playing an increasingly i Show more
Abstract Imaging contrast agents are widely investigated in preclinical and clinical studies, among which biogenic imaging contrast agents (BICAs) are developing rapidly and playing an increasingly important role in biomedical research ranging from subcellular level to individual level. The unique properties of BICAs, including expression by cells as reporters and specific genetic modification, facilitate various in vitro and in vivo studies, such as quantification of gene expression, observation of protein interactions, visualization of cellular proliferation, monitoring of metabolism, and detection of dysfunctions. Furthermore, in human body, BICAs are remarkably helpful for disease diagnosis when the dysregulation of these agents occurs and can be detected through imaging techniques. There are various BICAs matched with a set of imaging techniques, including fluorescent proteins for fluorescence imaging, gas vesicles for ultrasound imaging, and ferritin for magnetic resonance imaging. In addition, bimodal and multimodal imaging can be realized through combining the functions of different BICAs, which helps overcome the limitations of monomodal imaging. In this review, the focus is on the properties, mechanisms, applications, and future directions of BICAs. Show less
Mitochondria take up Ca 2+ through the mitochondrial calcium uniporter complex to regulate energy production, cytosolic Ca 2+ signaling, and cell death 1 , 2 . In mammals, the uniporter complex (u Show more
Mitochondria take up Ca 2+ through the mitochondrial calcium uniporter complex to regulate energy production, cytosolic Ca 2+ signaling, and cell death 1 , 2 . In mammals, the uniporter complex (uniplex) contains four core components: the pore-forming MCU, gatekeeper MICU1 and MICU2, and an auxiliary EMRE subunit essential for Ca 2+ transport 3 â 8 . To prevent detrimental Ca 2+ overload, the activity of MCU must be tightly regulated by MICUs, which sense the changes in cytosolic Ca 2+ concentrations to switch MCU on and off 9 , 10 . Here, we report cryo-EM structures of human mitochondrial calcium uniporter holocomplex in inhibited and Ca 2+ -activated states. These structures define the architecture of this multi-component Ca 2+ uptake machinery and reveal the gating mechanism by which MICUs control uniporter activity. This work provides a framework for understanding regulated Ca 2+ uptake in mitochondria and lends clues to modulate uniporter activity for treating mitochondrial Ca 2+ overload-related diseases. Show less
Mitochondrial Ca 2+ uptake plays a pivotal role both in cell energy balance and in cell fate determination. Studies on the role of mitochondrial Ca 2+ signaling in pathophysiology have been favored Show more
Mitochondrial Ca 2+ uptake plays a pivotal role both in cell energy balance and in cell fate determination. Studies on the role of mitochondrial Ca 2+ signaling in pathophysiology have been favored by the identification of the genes encoding the mitochondrial calcium uniporter (MCU) and its regulatory subunits. Thus, research carried on in the last years on one hand has determined the structure of the MCU complex and its regulation, on the other has uncovered the consequences of dysregulated mitochondrial Ca 2+ signaling in cell and tissue homeostasis. Whether mitochondrial Ca 2+ uptake can be exploited as a weapon to counteract cancer progression is debated. In this review, we summarize recent research on the molecular structure of the MCU, the regulatory mechanisms that control its activity and its relevance in pathophysiology, focusing in particular on its role in cancer progression. Show less