About
72
Publications
10,718
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,143
Citations
Introduction
Current institution
Publications
Publications (72)
By virtue of mitochondrial control of energy production, reactive oxygen species (ROS) generation, and maintenance of Ca²⁺ homeostasis, mitochondria play an essential role in modulating T cell function. The mitochondrial Ca²⁺ uniporter (MCU) is the pore-forming unit in the main protein complex mediating mitochondrial Ca²⁺ uptake. Recently, MCU has...
Balanced Ca2+ homeostasis is essential for cellular functions. STIM2 mediated Store-Operated Ca2+ Entry (SOCE) regulates cytosolic and ER Ca2+ concentrations, stabilizes dendritic spine formation and drives presynaptic spontaneous transmission and ER stress in neurons. Recently identified alternative spliced variants expand the STIM protein reperto...
Triggering receptor expressed on myeloid cells 2 (TREM2) is suggested to hamper antitumor immune response in multiple cancers. However, the role of TREM2 in oral squamous cell carcinoma (OSCC) and its expression in tumor-associated macrophages (TAMs) are unknown. In this study, TREM2 expression was analyzed in the primary tumors and corresponding l...
Pathogenic variants in SPAST, the gene coding for spastin, are the single most common cause of hereditary spastic
paraplegia, a progressive motor neuron disease. Spastin regulates key cellular functions, including microtubule-severing
and endoplasmic reticulum-morphogenesis. However, it remains unclear how alterations in these cellular
functions du...
Purpose
Strategies for Indolamine-2,3-dioxygenase 1 (IDO1) inhibition in cancer immunotherapy once produced encouraging results, but failed in clinical trials. Recent evidence indicates that immune cells in the tumour microenvironment, especially macrophages, contribute to immune dysregulation and therefore might play a critical role in drug resist...
Pathogenic variants in SPAST, the gene coding for spastin, are the single most common cause of hereditary spastic paraplegia, a progressive motor neuron disease. Spastin regulates key cellular functions, including microtubule-severing and endoplasmic reticulum-morphogenesis. However, it remains unclear how alterations in these cellular functions du...
Hypoxia-induced islet cell death, caused by an insufficient revascularization of the grafts, is a major obstacle for successful pancreatic islet transplantation. Recently, it has been reported that the nucleotide-binding oligomerization domain (NOD)-like receptor protein (NLRP)3 inflammasome is expressed in pancreatic islets and its loss protects a...
Immunological memory is important to protect humans against recurring diseases. Memory CD8⁺ T cells are required for quick expansion into effector cells but also provide immediate cytotoxicity against their targets. Whereas many functions of the two main cytotoxic subtypes, effector memory CD8⁺ T cells (TEM) and central memory CD8⁺ T cells (TCM), a...
Radiation therapy efficiently eliminates cancer cells and reduces tumor growth. To understand collateral agonistic and antagonistic effects of this treatment on the immune system, we examined the impact of x-ray irradiation on human T cells. We find that, in a major population of leukemic Jurkat T cells and peripheral blood mononuclear cells, clini...
Alternative splicing is a potent modifier of protein function. Stromal interaction molecule 1 (Stim1) is the essential activator of store-operated Ca2+ entry (SOCE) triggering activation of transcription factors. Here, we characterize Stim1A, a splice variant with an additional 31 amino acid domain inserted in frame within its cytosolic domain. Pro...
Efficacy of cytotoxic T lymphocyte (CTL)-based immunotherapy is still unsatisfactory against solid tumors, which are frequently characterized by condensed extracellular matrix. Here, using a unique 3D killing assay, we identify that the killing efficiency of primary human CTLs is substantially impaired in dense collagen matrices. Although the expre...
Background: Cardiovascular diseases (CVD) and chronic kidney disease (CKD) are highly prevalent, aggravate each other, and account for substantial mortality. Both conditions are characterized by activation of the innate immune system. The alarmin IL-1α is expressed in a variety of cell types promoting (sterile) systemic inflammation. The aim of the...
Immune responses involve mobilization of T cells within naïve and memory compartments. Tightly regulated Ca²⁺ levels are essential for balanced immune outcomes. How Ca²⁺ contributes to regulating compartment stoichiometry is unknown. Here, we show that plasma membrane Ca²⁺ ATPase 4 (PMCA4) is differentially expressed in human CD4⁺ T compartments yi...
Immune responses involve mobilization of T cells within naïve and memory compartments. Tightly regulated Ca2+ levels are essential for balanced immune outcomes. How Ca2+ contributes to regulating compartment stoichiometry is unknown. Here, we show that plasma membrane Ca2+ ATPase 4 (PMCA4) is differentially expressed in human CD4+ T compartments yi...
Solid tumors are often characterized by condensed extracellular matrix (ECM). The impact of dense ECM on cytotoxic T lymphocytes (CTL) function is not fully understood. Here, we report that CTL-mediated cytotoxicity is substantially impaired in dense collagen matrices. Although the intrinsic killing machinery including expression of cytotoxic prote...
Store-operated Ca2+-entry (SOCE) regulates basal and receptor-triggered Ca2+ signaling with STIM proteins sensing the endoplasmic reticulum (ER) Ca2+ content and triggering Ca2+ entry by gating Orai channels. Although crucial for immune cells, STIM1’s role in neuronal Ca2+ homeostasis is controversial. Here, we characterize a splice variant, STIM1B...
Immunological memory is an important concept to protect humans against recurring diseases. Memory CD8 ⁺ T cells are required for quick expansion into effector cells but also provide immediate cytotoxicity against their targets. Whereas many functions of the two main cytotoxic subtypes, effector memory CD8 ⁺ T cells (T EM ) and central memory CD8 ⁺...
The Ca²⁺ selective channel ORAI1 and endoplasmic reticulum (ER)-resident STIM proteins form the core of the channel complex mediating store operated Ca²⁺ entry (SOCE). Using liquid phase electron microscopy (LPEM), the distribution of ORAI1 proteins was examined at rest and after SOCE-activation at nanoscale resolution. The analysis of over seven h...
Store-operated calcium entry (SOCE) through STIM-gated ORAI channels governs vital cellular functions. In this context, SOCE controls cellular redox signaling and is itself regulated by redox modifications. However, the molecular mechanisms underlying this calcium-redox interplay and the functional outcomes are not fully understood. Here, we examin...
In CTLs: High glucose‐culture enhances thapsigargin‐induced SOCE but decreases target recognition‐induced Ca²⁺ influx.
High glucose‐culture regulates expression of ORAIs and STIMs without affecting glucose uptake.
More high glucose‐cultured CTLs are prone to necrosis after execution of killing.
The killing efficiency of cytotoxic T lymphocytes (CTLs) is tightly regulated by intracellular Ca2+ concentration. Glucose is the key energy source for CTLs, lack of which significantly impairs CTL activation, proliferation and effector functions. The impact of high glucose on Ca2+ influx in CTLs remains largely elusive. In this work, we stimulated...
Alternative splicing is a potent modifier of protein function. Stromal interaction molecule 1 (Stim1) is the essential activator molecule of store-operated Ca ²⁺ entry (SOCE) and a sorting regulator of certain ER proteins such as Stimulator of interferon genes (STING). Here, we characterize a conserved new variant, Stim1A, where splice-insertion tr...
The Ca ²⁺ selective channel ORAI1 and endoplasmic reticulum (ER)-resident STIM proteins form the core of the channel complex mediating store operated Ca ²⁺ entry (SOCE). Using liquid phase electron microscopy (LPEM) the distribution of ORAI1 proteins was examined at rest and after SOCE-activation at nanoscale resolution. The analysis of over seven...
Store-operated Ca2+-entry (SOCE) regulates basal and receptor-triggered Ca2+ signaling with STIM proteins sensing the endoplasmic reticulum (ER) Ca2+ content and triggering Ca2+ entry by gating Orai channels. Although crucial for immune cells, STIM1’s role in neuronal Ca2+ homeostasis is controversial. Here, we characterize a splice variant, STIM1B...
ORAI1 proteins form highly selective Ca2+ channels in the plasma membrane. Crystallographic data point towards a hexameric stoichiometry of ORAI1 channels, whereas optical methods postulated ORAI1 channels to reside as dimers at rest, and other data suggests a tetrameric configuration. Here, liquid-phase scanning transmission electron microscopy (S...
NLRP3-inflammasome-driven inflammation is involved in the pathogenesis of a variety of diseases. Identification of endogenous inflammasome activators is essential for the development of new anti-inflammatory treatment strategies. Here, we identified that apolipoprotein C3 (ApoC3) activates the NLRP3 inflammasome in human monocytes by inducing an al...
Basophils are a small population of innate immune cells, but their release of the cytokine interleukin-4 (IL-4) is important for mounting an efficient immune response against distinct parasites. Yoshikawa et al . (in the 9 April 2019 issue) showed that whereas STIM1 is essential for IL-4 release after stimulation of FcεRI, STIM2 mediates a delayed...
Release of Ca ²⁺ from endoplasmatic retriculum (ER) Ca ²⁺ stores causes stromal interaction molecules (STIM) in the ER membrane and ORAI proteins in the plasma membrane (PM) to interact and form the Ca ²⁺ release activated Ca ²⁺ (CRAC) channels, which represent a major Ca ²⁺ entry route in non-excitable cells and thus control various cell functions...
Quantitative Studies of Membrane Proteins in Whole Cells with Different Methods of Liquid Phase Scanning Transmission Electron Microscopy - Volume 25 Issue S1 - Diana B. Peckys, Dalia Alansary, Barbara Niemeyer, Niels de Jonge
In recent years, channels that mediate Store-Operated Calcium Entry (SOCE, i.e. the ability of cells to sense a decrease in endoplasmic reticulum luminal calcium and induce calcium entry across the plasma membrane) have been associated to a number of disorders, spanning from immune disorders to acute pancreatitis and have been suggested to be drugg...
Adjusting intracellular calcium signaling is an important feature in the regulation of immune cell function and survival. Here we show that miR-34a-5p, a small non-coding RNA that is deregulated in many common diseases, is a regulator of store-operated Ca2+ entry (SOCE) and calcineurin signaling. Upon miR-34a-5p overexpression, we observed both a d...
The oncometabolite (R)-2-hydroxyglutarate (R-2-HG) produced by isocitrate dehydrogenase (IDH) mutations promotes gliomagenesis via DNA and histone methylation. Here, we identify an additional activity of R-2-HG: tumor cell-derived R-2-HG is taken up by T cells where it induces a perturbation of nuclear factor of activated T cells transcriptional ac...
Application of Liquid Phase Scanning Transmission Electron Microscopy Methods for the Quantitative Study of Membrane Proteins in Whole Cells - Volume 24 Supplement - Diana B. Peckys, Indra N. Dahmke, Dalia Alansary, Barbara Niemeyer, Niels de Jonge
Differentiation of naïve CD4+T cells into effector subtypes with distinct cytokine profiles and physiological roles is a tightly regulated process, the imbalance of which can lead to an inadequate immune response or autoimmune disease. The crucial role of Ca2+signals, mainly mediated by the store operated Ca2+entry (SOCE) in shaping the immune resp...
Store-operated Ca²⁺ entry mediated by STIM1-gated Orai1 channels is essential to activate immune cells and its inhibition or gain-of-function can lead to immune dysfunction and other pathologies. Reactive oxygen species interacting with cysteine residues can alter protein function. Pretreatment of the Ca²⁺ selective Orai1 with the oxidant H2O2 redu...
ORAI1 proteins are ion channel subunits and the essential pore-forming units of the calcium release-activated calcium channel complex essential for T-cell activation and many other cellular processes. In this study, we used environmental scanning electron microscopy (ESEM) with scanning transmission electron microscopy (STEM) detection to image pla...
N-glycosylation of cell surface proteins affects protein function, stability, and interaction with other proteins.
Orai channels, which mediate store-operated Ca2+ entry (SOCE), are composed of N-glycosylated
subunits. Upon activation by Ca2+ sensor proteins (stromal interaction molecules STIM1 or STIM2) in the
endoplasmic reticulum, Orai Ca2+ chan...
Introduction: Antigen mediated stimulation of naïve CD4+ T cells triggers differentiation into effector regulatory or helper subtypes in a cytokine and antigen dependent manner. Imbalances between resulting subtypes lead to an inadequate immune response or to an autoimmune disease. The crucial role of Ca2+ signals in shaping the resulting immune re...
Understanding the molecular machinery underlying cellular function demands innovative microscopy techniques. Scanning transmission electron microscopy (STEM) of liquid specimens, so-called Liquid STEM, resolved the constituents of individual protein complexes within the context of intact cells in liquid state. Contrast was obtained on specific prot...
Cellular homeostasis relies upon precise regulation of Ca2+ concentration. Stromal interaction molecule (STIM) proteins regulate store-operated calcium entry (SOCE) by sensing Ca2+ concentration in the ER and forming oligomers to trigger Ca2+ entry through plasma membrane-localized Orai1 channels. Here we characterize a STIM2 splice variant, STIM2....
Orai1 subunits interacting with STIM1 molecules comprise the major components responsible for calcium release-activated calcium (CRAC) channels. The homologs Orai2 and Orai3 yield smaller store-operated currents when overexpressed and are mostly unable to substitute Orai1. Orai3 subunits are also essential components of store independent channel co...
Ca2+ signaling depends on a tight regulation of the intracellular Ca2+ concentration. Alterations in basal Ca2+ can lead to various diseases and likely contribute to development of abnormal growth. Different regulators such as calmodulin and Ca2+ pumps limit cytosolic [Ca2+] and their down-regulation by siRNA lead to an increased basal [Ca2+]. Anot...
Cell homeostasis and Ca2+ signaling depend on a tight regulation of the intracellular Ca2+ concentration. Alterations in basal Ca2+ can lead to various diseases and likely contribute to development of abnormal growth. Different regulators such as calmodulin and Ca2+ pumps limit cytosolic [Ca2+] and their down-regulation by siRNA lead to an increase...
Although ICRAC and other store-operated currents are often analyzed by Ca(2+) imaging, whole-cell patch clamp, described here, is the preferred technique to analyze ICRAC whenever possible. The whole-cell patch-clamp protocol can even be used to record endogenous ICRAC in primary cells. The small endogenous current size of ICRAC requires some preca...
Endogenous calcium release-activated channel (CRAC) currents are usually quite small and not always easy to measure using the patch-clamp technique. While we have, for instance, successfully recorded very small CRAC currents in primary human effector T cells, we have not yet managed to record CRAC in naïve primary human T cells. Many groups, includ...
Depletion of internal Ca(2+) stores activates store-operated Ca(2+) channels. The most prominent members of this class of channels are Ca(2+) release-activated Ca(2+) (CRAC) channels, which are present in a variety of cell types including immune cells. CRAC channels are composed of ORAI proteins, which are activated by endoplasmic reticulum-bound S...
T cell receptor mediated activation requires the influx of calcium from the extracellular medium. Here, the endoplasmic reticulum (ER) Ca2+ sensor STIM1 reports the decrease in luminal [Ca2+] caused by IP3 receptor activity, clusters and directly binds and activates Orai1 channels, providing Ca2+ influx (store-operated, SOCE) essential for immune c...
A drop of endoplasmic reticulum Ca2+ concentration triggers its Ca2+ ssensor protein stromal interaction molecule 1 (STIM1) to oligomerize and accumulate within endoplasmic reticulum-plasma
membrane junctions where it activates Orai1 channels, providing store-operated Ca2+ entry. To elucidate the functional significance of N-glycosylation sites of...
Using biochemical and electrophysiological methods we found that pentam-idine exclusively inhibits hERG export from the endoplasmic reticulum to the cell surface in a heterologous expression system as well as in cardiomyo-cytes. hERG trafficking inhibition could be rescued in the presence of the pharmacological chaperone astemizole. We used rescue...
Cell polarization enables restriction of signalling into microdomains. Polarization of lymphocytes following formation of a mature immunological synapse (IS) is essential for calcium-dependent T-cell activation. Here, we analyse calcium microdomains at the IS with total internal reflection fluorescence microscopy. We find that the subplasmalemmal c...
Ca(2+) homeostasis controls a diversity of cellular processes including proliferation and apoptosis. A very important aspect of Ca(2+) signaling is how different Ca(2+) signals are translated into specific cell functions. In T cells, Ca(2+) signals are induced following the recognition of antigen by the T cell receptor and depend mainly on Ca(2+) i...
Store-operated Ca(2+) entry is a major Ca(2+) entry mechanism that is present in most cell types. In immune cells, store-operated Ca(2+) entry is almost exclusively mediated by Ca(2+) release-activated Ca(2+) (CRAC) channels. Ca(2+) entry through these channels and the corresponding cytosolic Ca(2+) signals are required for many immune cell functio...
Reactive oxygen species (ROS) are involved in many physiological and pathophysiological cellular processes. We used lymphocytes, which are exposed to highly oxidizing environments during inflammation, to study the influence of ROS on cellular function. Calcium ion (Ca(2+)) influx through Ca(2+) release-activated Ca(2+) (CRAC) channels composed of p...
Phagocytes play an essential role in host defence against pathogens by generating reactive oxygen species (ROS). Effector T helper (Th) cells migrating to sites of infection will be exposed to this highly oxidative environment. Here we show how Th-cells respond and adapt to ROS. Oxidation affects different Ca2+-signalling pathways essential for T-c...
Ca(2+) homeostasis requires balanced uptake and extrusion, and dysregulation leads to disease. TRPV6 channels are homeostasis regulators, are upregulated in certain cancers, and show an unusual allele-specific evolution in humans. To understand how Ca(2+) uptake can be adapted to changes in metabolic status, we investigate regulation of Ca(2+)-infl...
The calcium selective ion channel TRPV6 shows a highly unusual evolution of one of its polymorphic alleles which might have conferred a selective advantage during migration of humans out of Africa. Because the ancestral allele contains an additional PKC consensus site, we analyzed regulation by intracellular ATP and phosphorylation. We found that A...
TRPM (transient receptor potential melastatin-like) channels are distinct from many other members of the transient receptor potential family in regard to their
overall size (>1000 amino acids), the lack of N-terminal ankyrin-like repeats, and hydrophobicity predictions that may allow
for more than six transmembrane regions. Common to each TRPM memb...
