Andrea Fleig

Andrea Fleig
The Queen's Medical Center · Queen's Center for Biomedical Research

PhD MBA

About

122
Publications
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Publications

Publications (122)
Article
Cannabis sativa has long been known to affect numerous biological activities. Although plant extracts, purified cannabinoids, or synthetic cannabinoid analogs have shown therapeutic potential in pain, inflammation, seizure disorders, appetite stimulation, muscle spasticity, and treatment of nausea/vomiting, the underlying mechanisms of action remai...
Article
TRPM7 is a non-selective divalent cation channel with an alpha-kinase domain. Corresponding with its broad expression, TRPM7 has a role in a wide range of cell functions, including proliferation, migration, and survival. Growing evidence shows that TRPM7 is also aberrantly expressed in various cancers, including brain cancers. Because ion channels...
Article
Full-text available
Cancer is the second leading cause of death worldwide and accounted for an estimated 9.6 million deaths, or 1 in 6 deaths, in 2018. Despite recent advances in cancer prevention, diagnosis, and treatment strategies, the burden of this disease continues to grow with each year, with dire physical, emotional, and economic consequences for all levels of...
Article
Full-text available
Transient receptor potential melastatin 7 (TRPM7), a calcium-permeable, ubiquitously expressed ion channel, is critical for axonal development, and mediates hypoxic and ischemic neuronal cell death in vitro and in vivo. However, the downstream mechanisms underlying the TRPM7-mediated processes in physiology and pathophysiology remain unclear. In th...
Article
Glioblastoma (GBM) is the most common malignant primary brain tumour originating in the CNS. Median patient survival is <15 months with standard treatment which consists of surgery alongside radiation therapy and temozolomide chemotherapy. However, because of the aggressive nature of GBM, and the significant toxicity of these adjuvant therapies, lo...
Article
Ion channels are the third largest class of targets for therapeutic drugs. The pharmacology of ion channels is an important research area for identifying new treatment options for human diseases. The past decade or so has seen increasing interest in an ion channel protein belonging to the transient receptor potential (TRP) family, namely the melast...
Article
Full-text available
TRPM7 belongs to the Transient Receptor Potential Melastatin family of ion channels and is a divalent cation-conducting ion channel fused with a functional kinase. TRPM7 plays a key role in a variety of diseases, including neuronal death in ischemia, cancer, cardiac atrial fibrillation, malaria invasion. TRPM7 is aberrantly over-expressed in lung,...
Article
Prior to maturation, mouse oocytes are arrested at the germinal vesicle (GV) stage during which they experience constitutive calcium (Ca2+) influx and spontaneous Ca2+ oscillations. The oscillations cease during maturation but Ca2+ influx continues, as the oocytes' internal stores attain maximal content at the culmination of maturation, the metapha...
Article
Full-text available
High-glucose (HG) levels and hyperglycemia associated with diabetes are known to cause neuronal damage. The detailed molecular mechanisms, however, remain to be elucidated. Here, we investigated the role of transient receptor potential melastatin 7 (TRPM7) channels in HG-mediated endoplasmic reticulum stress (ERS) and injury of NS20Y neuronal cells...
Article
Full-text available
The melastatin-related transient receptor potential member 7 (TRPM7) is a unique fusion protein with both ion channel function and enzymatic α-kinase activity. TRPM7 is essential for cellular systemic magnesium homeostasis and early embryogenesis; it promotes calcium transport during global brain ischemia and emerges as a key player in cancer growt...
Article
Full-text available
Background: Magnesium (Mg2+) is an essential cation implicated in carcinogenesis, solid tumor progression and metastatic potential. The Transient Receptor Potential Melastatin Member 7 (TRPM7) is a divalent ion channel involved in cellular and systemic Mg2+ homeostasis. Abnormal expression of TRPM7 is found in numerous cancers, including colon, im...
Article
TRPM2 is a Ca²⁺-permeable, nonselective cation channel that plays a role in oxidant-induced cell death, insulin secretion, and cytokine release. Few TRPM2 inhibitors have been reported, which hampers the validation of TRPM2 as a drug target. While screening our in-house marine-derived chemical library, we identified scalaradial and 12-deacetylscala...
Data
Table of LC-MSMS evidence and quantitative statistics for the triple labelling experiment in which EBA-175 treated erythrocytes were labelled with heavy isotope (H), EBA-175+FTY720 treated erythrocyte proteins were labelled with medium isotope (M) versus untreated erythrocyte proteins labelled with light isotope (L). DOI: http://dx.doi.org/10.7554/...
Data
Table of LC-MSMS evidence and quantitative statistics for the double labelling experiment in which EBA-175 treated erythrocyte proteins were labelled with heavy isotope (H) versus untreated that were labelled with light isotope (L). DOI: http://dx.doi.org/10.7554/eLife.21083.012
Article
Full-text available
TRPM7 is a member of the Transient-Receptor-Potential Melastatin ion channel family. TRPM7 is a unique fusion protein of an ion channel and an α-kinase. Although mammalian TRPM7 is well characterized biophysically and its pivotal role in cancer, ischemia and cardiovascular disease is becoming increasingly evident, the study of TRPM7 in mouse models...
Article
Full-text available
CNNM2 is associated with the regulation of serum Mg concentration, and when mutated, with severe familial hypomagnesemia. The function and cellular localization of CNNM2 and its isomorphs (Iso) remain controversial. The objective of this work was to examine the following: (1) the transcription-responsiveness of CNNM2 to Mg starvation, (2) the cellu...
Article
Key points: The Mg(2+) and Ca(2+) conducting transient receptor potential melastatin 7 (TRPM7) channel-enzyme (chanzyme) has been implicated in immune cell function. Mice heterozygous for a TRPM7 kinase deletion are hyperallergic, while mice with a single point mutation at amino acid 1648, silencing kinase activity, are not. As mast cell mediators...
Article
Key points: Pharmacological and molecular inhibition of transient receptor potential melastatin 7 (TRPM7) reduces store-operated calcium entry (SOCE). Overexpression of TRPM7 in TRPM7-/-cells restores SOCE. TRPM7 is not a store-operated calcium channel. TRPM7 kinase rather than channel modulates SOCE. TRPM7 channel activity contributes to the main...
Article
Full-text available
TRPM7 is an unusual bi-functional protein containing an ion channel covalently linked to a protein kinase domain. TRPM7 is implicated in regulating cellular and systemic magnesium homeostasis. While the biophysical properties of TRPM7 ion channel and its function are relatively well characterized, the function of the TRPM7 enzymatically active kina...
Article
Full-text available
Transient receptor potential melastatin 7 (TRPM7) is a calcium-permeable divalent cation channel and mediates neuronal cell death under ischemic stresses. In this study, we investigated the contribution of TRPM7 to neuronal development in mouse primary hippocampal neurons. We demonstrated that TRPM7 channels are highly expressed in the tips of the...
Article
Full-text available
Intracellular levels of the divalent cations Ca2+ and Mg2+ are important regulators of cell cycle and proliferation. However, the precise mechanisms by which they are regulated in cancer remain incompletely understood. The channel kinases TRPM6 and TRPM7 are gatekeepers of human Ca2+/Mg2+ metabolism. Here, we investigated the human neuroblastoma ce...
Article
Deviations from physiological pH (∼pH 7.2) as well as altered Ca(2+) signaling play important roles in immune disease and cancer. One of the most ubiquitous pathways for cellular Ca(2+) influx is the store-operated Ca(2+) entry (SOCE) or Ca(2+) release-activated Ca(2+) current (ICRAC), which is activated upon depletion of intracellular Ca(2+) store...
Article
Full-text available
The channel kinases TRPM6 and TRPM7 are fusion proteins with an ion transport domain and an enzymatically active kinase domain. TRPM7 has been found in every mammalian tissue investigated to date. The two-in-one protein structure, the ubiquitous expression profile, and the protein's unique biophysical characteristics that enable divalent ion transp...
Article
Full-text available
The transient receptor potential melastatin member 7 (TRPM7) and member 6 (TRPM6) are divalent cation channel kinases essential for magnesium (Mg2+) homeostasis in vertebrates. It remains unclear how TRPM6 affects divalent cation transport and whether this involves functional homomeric TRPM6 plasma membrane channels or heteromeric channel assemblie...
Article
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The 41st family of solute carriers (SLC41) comprises three members A1, A2, and A3, which are distantly homologous to bacterial Mg2+ channel MgtE. SLC41A1 was recently characterized as being an Na+/Mg2+ exchanger (NME; a predominant cellular Mg2+-efflux system). Little is known about the exact function of SLC41A2 and SLC41A3, although, these protein...
Article
Full-text available
Cell migration depends on the dynamic formation and turnover of cell adhesions and is tightly controlled by actomyosin contractility and local Ca(2+) signals. The divalent cation channel TRPM7 (Transient Receptor Potential cation channel, subfamily Melastatin, member 7) has recently received much attention as a regulator of cell adhesion, migration...
Article
Full-text available
Airway inflammation and asthma have been linked to oxidative stress and the melastatin-related transient receptor potential cation channel, member 2 (TRPM2), which can be activated by reactive oxygen species (ROS), has emerged as a potential therapeutic target for inflammatory diseases. Using TRPM2 deficient (TRPM2-/-) mice, we investigated whether...
Article
Full-text available
Transient receptor potential melastatin 7 (TRPM7) is a divalent-selective cation channel fused to an atypical α-kinase. TRPM7 is a key regulator of cell growth and proliferation, processes accompanied by mandatory cell volume changes. Osmolarity-induced cell volume alterations regulate TRPM7 through molecular crowding of solutes that affect channel...
Article
Full-text available
Transient receptor potential melastatin 7 (TRPM7) channels represent the major magnesium-uptake mechanism in mammalian cells and are key regulators of cell growth and proliferation. They are expressed abundantly in a variety of human carcinoma cells controlling survival, growth, and migration. These characteristics are the basis for recent interest...
Article
Full-text available
Chemokines induce calcium (Ca(2+)) signaling and chemotaxis in dendritic cells (DCs), but the molecular players involved in shaping intracellular Ca(2+) changes remain to be characterized. Using siRNA and knockout mice, we show that in addition to inositol 1,4,5-trisphosphate (IP(3))-mediated Ca(2+) release and store-operated Ca(2+) entry (SOCE), t...
Article
Full-text available
Store-operated Ca(2+) entry is controlled by the interaction of stromal interaction molecules (STIMs) acting as endoplasmic reticulum ER Ca(2+) sensors with calcium release-activated calcium (CRAC) channels (CRACM1/2/3 or Orai1/2/3) in the plasma membrane. Here, we report structural requirements of STIM1-mediated activation of CRACM1 and CRACM3 usi...
Article
Full-text available
Mg(2+) is the second-most abundant cation in animal cells and is an essential cofactor in numerous enzymatic reactions. The molecular mechanisms controlling Mg(2+) balance in the organism are not well understood. In this study, we report identification of TRPM7, a bifunctional protein containing a protein kinase fused to an ion channel, as a key re...
Article
Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) play a role in both innate immunity as well as cellular injury. H2O2 induces changes in intracellular calcium ([Ca(2+)]i) in many cell types and this seems to be at least partially mediated by transient receptor potential melastatin 2 (TRPM2) in cells that express this channel. Here we...
Article
Full-text available
Insulin secretion in β-pancreatic cells due to glucose stimulation requires the coordinated alteration of cellular ion concentrations and a substantial membrane depolarization to enable insulin vesicle fusion with the cellular membrane. The cornerstones of this cascade are well characterized, yet current knowledge argues for the involvement of addi...
Article
Full-text available
TRPM7 is a ubiquitously expressed and constitutively active divalent cation channel essential for cell survival and proliferation because it provides a mechanism for Mg2+ entry. This makes the channel an attractive target for proliferative diseases. In keeping with its role in Mg2+ homeostasis, TRPM7 is inhibited by intracellular Mg2+ and Mg-ATP. T...
Article
TRPM2 is a calcium-permeable non-selective cation channel expressed in the plasma membrane and in lysosomes that is critically involved in aggravating reactive oxygen species (ROS)-induced inflammatory processes and has been implicated in cell death. TRPM2 is gated by ADP-ribose (ADPR) and modulated by physiological processes that produce peroxide,...
Article
Store-operated calcium entry (SOCE) or calcium release-activated calcium current (I(CRAC)) is a critical pathway to replenish intracellular calcium stores, and plays indispensable roles in cellular functions such as antigen-induced T lymphocyte activation. Despite the importance of I(CRAC) in cellular functions, lack of potent and specific inhibito...
Article
The store-operated, calcium release-activated calcium current I(CRAC) is activated by the depletion of inositol 1,4,5-trisphosphate (IP(3))-sensitive stores. The significantly different dose-response relationships of IP(3)-mediated Ca(2+) release and CRAC channel activation indicate that I(CRAC) is activated by a functionally, and possibly physical...
Article
Full-text available
TRPM2 is a Ca2+-permeable cation channel that is specifically activated by adenosine diphosphoribose (ADPR). Channel activation in the plasma membrane leads to Ca2+ influx and has been linked to apoptotic mechanisms. The primary agonist, ADPR, is produced both extra- and intracellularly and causes increases in intracellular calcium concentration ([...
Data
Clofazimine does not affect the enzymatic activity of calcineurin in vitro. (A) Clofazimine does not inhibit the protein phosphatase activity of calcineurin in vitro. 20 mM p-nitrophenylphosphate was incubated with purified recombinant calcineurin A/B and calmodulin in the presence of 1 mM calcium or 5 mM EGTA at 30°C. The progress of the reaction...
Data
Effects of clofazimine on AP-1 luciferase reporter gene and the nuclear translocation of NFAT in response to ionomycin treatment. (A) Dose-dependent enhancement of the AP-1 luciferase reporter gene by CsA (n = 6). (B) Clofazimine inhibits EGFP-NFATc3 nuclear translocation in Jurkat T cells stimulated by 1 µM ionomycin. Images were taken 30 minutes...
Data
Clofazimine alters calcium oscillation patterns in Jurkat T cells without affecting reconstituted ICRAC in HEK293 cells. (A, B) Time-dependent increase in the population of cells that are sensitive to clofazimine. Jurkat T cells were incubated with clofazimine for varied lengths of time before 1 µM TG was added. Images were taken 30 min after 2 mM...
Data
Knockdown of Kv1.3 did not affect the sensitivity of the IL-2 luciferase reporter to CsA. The IC50 for control EGFP-siRNA lentiviral transduced Jurkat T cells was 2.5±0.6 nM, and that for Kv1.3 lentiviral 4 transduced T cells was 2.6±0.7 nM (n = 6). (0.00 MB TIF)
Data
Supporting Materials and Methods (0.10 MB DOC)
Data
Effect of 10 µM clofazimine on heterologous Kv1.1, Kv1.2 Kv1.5 and Kv3.1. (A) Average time course of mouse Kv1.1 currents stably expressed in L929 cells. Control cells (closed circles, n = 5, no application) and cells superfused with 10 µM clofazimine added to the standard extracellular solution (open circles, n = 6) as indicated by the black bar....
Data
Inhibition of Kv channels by 10 µM clofazimine assessed at 0 mV (red bars) or +80 mV (black bars). Same cells as in Fig. 3D and Fig. S4 were used. Note the increased inhibitory effect at 0 mV for all Kv channels displayed except Kv1.3. (0.19 MB TIF)
Data
Effects of clofazimine on mouse TCR-mediated IL-2 production and mixed lymphocyte reaction in murine T cells. (A) Dose response of IL-2 production from anti-CD3/anti-CD28-stimulated mouse primary T cells to different concentrations of clofazimine (n = 3). (B) Biphasic effects of clofazimine on mouse mixed lymphocyte reaction (n = 3). (0.00 MB TIF)
Data
Effects of Psora-4 on calcium influx and the activation of different reporter genes in Jurkat T cells. (A) Calcium influx in Jurkat T cells was inhibited by 10 µM psora-4 in a heterogeneous fashion. Psora-4 was added 5 minutes before stimulation with 1 µM TG. Representative images were taken 30 minutes after 2 mM calcium was added. The color gradie...
Chapter
The molecular characterization of the genes encoding the transient receptor potential (TRP) cation channels found in Drosophila photoreceptors gave rise to a systematic cloning strategy for mammalian isoforms. Using expressed sequence tag (EST) and genomic database searches, at least 20 new mammalian TRP-related genes have been cloned and the resul...
Article
Full-text available
Reactive oxygen species (ROS) induce chemokines responsible for the recruitment of inflammatory cells to sites of injury or infection. Here we show that the plasma membrane Ca(2+)-permeable channel TRPM2 controls ROS-induced chemokine production in monocytes. In human U937 monocytes, hydrogen peroxide (H(2)O(2)) evokes Ca(2+) influx through TRPM2 t...
Article
Full-text available
2-Aminoethoxydiphenyl borate (2-APB) has emerged as a useful pharmacological tool in the study of store-operated Ca(2+) entry (SOCE). It has been shown to potentiate store-operated Ca(2+) release-activated Ca(2+) (CRAC) currents at low micromolar concentrations and to inhibit them at higher concentrations. Initial experiments with the three CRAC ch...
Article
The Ca(2+)-permeable TRPM2 channel is a dual function protein that is activated by intracellular ADPR through its enzymatic pyrophosphatase domain with Ca(2+) acting as a co-factor. Other TRPM2 regulators include cADPR, NAADP and H(2)O(2), which synergize with ADPR to potentiate TRPM2 activation. Although TRPM2 has been thoroughly characterized in...
Article
Full-text available
The molecular biology of mammalian magnesium transporters and their interrelations in cellular magnesium homeostasis are largely unknown. Recently, the mouse SLC41A1 protein was suggested to be a candidate magnesium transporter with channel-like properties when overexpressed in Xenopus laevis oocytes. Here, we demonstrate that human SLC41A1 overexp...
Conference Paper
Full-text available
Background: Despite extensive functional evidence for the existence of various regulated Mg2+ transport proteins, only two plasmalemal channels (TRPM6, TRPM7), and mitochondrial channel (Mrs2p) have been molecularly confirmed to be involved in Mg2+ transport in mammalian cells. The recent identification of putative Mg2+ transporter SLC41A1 therefor...
Article
Full-text available
STIM1 and CRACM1 (or Orai1) are essential molecular components mediating store-operated Ca2+ entry (SOCE) and Ca2+ release-activated Ca2+ (CRAC) currents. Although STIM1 acts as a luminal Ca2+ sensor in the endoplasmic reticulum (ER), the function of STIM2 remains unclear. Here we reveal that STIM2 has two distinct modes of activating CRAC channels...
Article
The pancreas provides digestive enzymes for the small intestine and hormones that regulate blood glucose levels in the body. The two pancreatic endocrine hormones, insulin and glucagon, produced by the pancreatic islet cells, are responsible for maintaining the blood glucose levels in the body. Like all endocrine cells, insulin is a protein that bi...