The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, ...electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.
Pharmacological targeting of mitochondrial ion channels is emerging as a promising approach to eliminate cancer cells; as most of these channels are differentially expressed and/or regulated in ...cancer cells in comparison to healthy ones, this strategy may selectively eliminate the former. Perturbation of ion fluxes across the outer and inner membranes is linked to alterations of redox state, membrane potential and bioenergetic efficiency. This leads to indirect modulation of oxidative phosphorylation, which is/may be fundamental for both cancer and cancer stem cell survival. Furthermore, given the crucial contribution of mitochondria to intrinsic apoptosis, modulation of their ion channels leading to cytochrome c release may be of great advantage in case of resistance to drugs triggering apoptotic events upstream of the mitochondrial phase. In the present review, we give an overview of the known mitochondrial ion channels and of their modulators capable of killing cancer cells. In addition, we discuss state-of-the-art strategies using mitochondriotropic drugs or peptide-based approaches allowing a more efficient and selective targeting of mitochondrial ion channel-linked events.
The biochemical activities of plant flavonoids and stilbenoids point to many health-related applications, hampered however by a low bioavailability associated with rapid metabolic modification. A ...possible approach to overcome this obstacle is the development of prodrugs. In this review we provide some background information and summarize the efforts made so far to obtain suitable precursors of the two best known model polyphenols belonging to the classes just mentioned, quercetin and resveratrol. Prodrug design needs to take into account two key aspects: the nature of the chemical bond linking the core molecule to the protecting substituent, and the substituent itself, which can impart desirable physico-chemical properties. Only recently a systematic study of the several possible combinations has begun. Most bond systems tested so far appear to be either too stable or too unstable under physiological conditions. A range of substituent moieties is available, allowing the modulation of properties such as water solubility and the ability to permeate biomembranes. Work so far has been largely performed in vitro, and more in vivo experiments are definitely needed for a reliable assessment of the potentialities of the classes of prodrugs produced so far and of those still awaiting creation.
The field of mitochondrial ion channels has undergone a rapid development during the last three decades, due to the molecular identification of some of the channels residing in the outer and inner ...membranes. Relevant information about the function of these channels in physiological and pathological settings was gained thanks to genetic models for a few, mitochondria‐specific channels. However, many ion channels have multiple localizations within the cell, hampering a clear‐cut determination of their function by pharmacological means. The present review summarizes our current knowledge about the ins and outs of mitochondrial ion channels, with special focus on the channels that have received much attention in recent years, namely, the voltage‐dependent anion channels, the permeability transition pore (also called mitochondrial megachannel), the mitochondrial calcium uniporter and some of the inner membrane‐located potassium channels. In addition, possible strategies to overcome the difficulties of specifically targeting mitochondrial channels versus their counterparts active in other membranes are discussed, as well as the possibilities of modulating channel function by small peptides that compete for binding with protein interacting partners. Altogether, these promising tools along with large‐scale chemical screenings set up to identify new, specific channel modulators will hopefully allow us to pinpoint the actual function of most mitochondrial ion channels in the near future and to pharmacologically affect important pathologies in which they are involved, such as neurodegeneration, ischaemic damage and cancer.
Linked Articles
This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.22/issuetoc
Mitochondrial diseases impair oxidative phosphorylation and ATP production, while effective treatment is still lacking. Defective complex III is associated with a highly variable clinical spectrum. ...We show that pyocyanin, a bacterial redox cycler, can replace the redox functions of complex III, acting as an electron shunt. Sub-μM pyocyanin was harmless, restored respiration and increased ATP production in fibroblasts from five patients harboring pathogenic mutations in TTC19, BCS1L or LYRM7, involved in assembly/stabilization of complex III. Pyocyanin normalized the mitochondrial membrane potential, and mildly increased ROS production and biogenesis. These in vitro effects were confirmed in both Drosophila
and in Danio rerio
, as administration of low concentrations of pyocyanin significantly ameliorated movement proficiency. Importantly, daily administration of pyocyanin for two months was not toxic in control mice. Our results point to utilization of redox cyclers for therapy of complex III disorders.
Purified F-ATP synthase dimers of yeast mitochondria display Ca2+-dependent channel activity with properties resembling those of the permeability transition pore (PTP) of mammals. After treatment ...with the Ca2+ ionophore ETH129, which allows electrophoretic Ca2+ uptake, isolated yeast mitochondria undergo inner membrane permeabilization due to PTP opening. Yeast mutant strains ΔTIM11 and ΔATP20 (lacking the e and g F-ATP synthase subunits, respectively, which are necessary for dimer formation) display a striking resistance to PTP opening. These results show that the yeast PTP originates from F-ATP synthase and indicate that dimerization is required for pore formation in situ.
Whether channel formation is a general feature of F-ATP synthase dimers across species is unknown.
Yeast F-ATP synthase dimers form Ca2+-dependent channels, and the e and g subunits facilitate pore formation in situ through dimerization.
F-ATP synthase dimers form the permeability transition pore of yeast.
Ca2+-dependent channel formation is a conserved feature of F-ATP synthases.
Resveratrol derivatives as a pharmacological tool Biasutto, Lucia; Mattarei, Andrea; Azzolini, Michele ...
Annals of the New York Academy of Sciences,
September 2017, Letnik:
1403, Številka:
1
Journal Article
Recenzirano
Prodrugs of resveratrol are under development. Among the long‐term goals, still largely elusive, are (1) modulating physical properties (e.g., water‐soluble derivatives bearing polyethylene glycol ...chains), (2) changing distribution in the body (e.g., galactosyl derivatives restricted to the intestinal lumen), (3) increasing absorption from the gastrointestinal tract (e.g., derivatives imitating the natural substrates of endogenous transporters), and (4) hindering phase II metabolism (e.g., temporarily blocking the hydroxyls), all contributing to (5) increasing bioavailability. The chemical bonds that have been tested for functionalization include carboxyester, acetal, and carbamate groups. A second approach, which can be combined with the first, seeks to reinforce or modify the biochemical activities of resveratrol by concentrating the compound at specific subcellular sites. An example is provided by mitochondria‐targeted derivatives. These proved to be pro‐oxidant and cytotoxic in vitro, selectively killing fast‐growing and tumor cells when supplied in the low micromolar range. This suggests the possibility of anticancer applications.
Pancreatic cancers are among the most ominous, and among the most studied. Their complexities have provided ample material for a huge investigative effort, which is briefly surveyed in this review. ...Eradication by surgery has proven extremely difficult, and a successful chemotherapeutic approach is desperately needed. Treatment with "traditional" anticancer drugs, such as benchmark gemcitabine or the current standard-of-care FOLFIRINOX quaternary combination increase the mean overall survival by only a few months and often leads to chemoresistance. Much work is therefore currently devoted to potentiating our pharmacological weapons by accurate targeting and, in particular, by acting on the dense tumoral stroma, a distinctive feature of PDAC accounting for much of the therapeutic difficulty. We give an overview of recent developments, touching on the major aspects of PDAC physiology and biochemistry, currently-used and experimental drugs, and targeting technologies under development. A few papers are discussed in some detail to help provide a sense of how the field is moving.
The inner membrane of the ATP-producing organelles of endosymbiotic origin, mitochondria, has long been considered to be poorly permeable to cations and anions, since the strict control of inner ...mitochondrial membrane permeability is crucial for efficient ATP synthesis. Over the past 30 years, however, it has become clear that various ion channels—along with antiporters and uniporters—are present in the mitochondrial inner membrane, although at rather low abundance. These channels are important for energy supply, and some are a decisive factor in determining whether a cell lives or dies. Their electrophysiological and pharmacological characterisations have contributed importantly to the ongoing elucidation of their pathophysiological roles. This review gives an overview of recent advances in our understanding of the functions of the mitochondrial potassium channels identified so far. Open issues concerning the possible molecular entities giving rise to the observed activities and channel protein targeting to mitochondria are also discussed.
Wnt signaling affects fundamental development pathways and, if aberrantly activated, promotes the development of cancers. Wnt signaling is modulated by different factors, but whether the ...mitochondrial energetic state affects Wnt signaling is unknown. Here, we show that sublethal concentrations of different compounds that decrease mitochondrial ATP production specifically downregulate Wnt/β-catenin signaling in vitro in colon cancer cells and in vivo in zebrafish reporter lines. Accordingly, fibroblasts from a GRACILE syndrome patient and a generated zebrafish model lead to reduced Wnt signaling. We identify a mitochondria-Wnt signaling axis whereby a decrease in mitochondrial ATP reduces calcium uptake into the endoplasmic reticulum (ER), leading to endoplasmic reticulum stress and to impaired Wnt signaling. In turn, the recovery of the ATP level or the inhibition of endoplasmic reticulum stress restores Wnt activity. These findings reveal a mechanism that links mitochondrial energetic metabolism to the control of the Wnt pathway that may be beneficial against several pathologies.
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•Mitochondrial ATP is necessary to sustain Wnt signaling•Respiratory chain complex inhibition leads to reduced calcium uptake into the ER•A defect in complex III assembly causes impairments in Wnt signaling
Wnt signaling and mitochondrial fitness are both important for cell fate. Costa et al. demonstrate that the reduction of mitochondrial ATP production leads to the induction of ER stress and, in turn, decreases canonical Wnt/β-catenin signaling in vitro and in vivo.
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