Tommy Nordström

University of Helsinki | HY · Institute of Biomedicine / Physiology

Hyperpolarization-activated cyclic nucleotide-gated channels (HCN channels) are involved in spontaneous activity in many electrically active cell types such as cardiomyocytes and neurons. In this study, the role of HCN channels in proliferation and migration of Nestin and Sox2 expressing embryonic neural progenitor cells (NPC) originating from the...

Background and aims In focal areas of advanced human atherosclerotic lesions, the intimal fluid is acidic. An acidic medium impairs the ABCA1-mediated cholesterol efflux from macrophages, so tending to increase their content of free cholesterol, which is then available for esterification by the macrophage enzyme ACAT1. Here we investigated whether...

Cell-cell communication plays a central role in the guidance of migrating neurons during the development of the cerebral cortex. Neuregulins (NRGs) are essential mediators for migration and maintenance of the radial glial scaffold. We show here that soluble NRG reduces neuronal motility, causes transition of bipolar cells to multipolar ones and ind...

Self-renewing neural stem cells and progenitor cells are cell populations that generate radial glial cells and neurons through asymmetric division. Regulation of intracellular pH in stem cells with high metabolic activity is critical for both cell signaling and proliferation. We have recently found that a S0859-inhibitable electrogenic Na/HCO3 co-t...

A stroke causes a hypoxic brain microenvironment that alters neural cell metabolism resulting in cell membrane hyperpolarization and intracellular acidosis. We studied how intracellular pH (pH i ) is regulated in differentiated mouse neural progenitor cells during hyperpolarizing conditions, induced by prompt reduction of the extracellular K ⁺ conc...

Virus-induced cytotoxicity (LDH release) measurements. (A) Optopatch-transduced hiPSC-CMs revealed no significant increase in cytotoxicity or cytolysis compared to control (Cor.4U® non-transduced cells, dotted line), measured at 24 h after lentiviral transduction. (B) Neither CaViar-transduced hiPSCs revealed any significant cytotoxicity over contr...

Confluent monolayer of hiPSC-derived cardiomyocytes. Phase contrast microscopy image (20X) showing typical structural characteristics and cell density of confluent monolayer of Cor.4U® hiPSC-CMs cultured on Geltrex-coated glass-bottom dishes for optogenetic imaging. Scale bar = 100 μm.

Current cardiac drug safety assessments focus on hERG channel block and QT prolongation for evaluating arrhythmic risks, whereas the optogenetic approach focuses on the action potential waveform generated by a monolayer of human cardiomyocytes beating synchronously, thus assessing the contribution of several ion channels on the overall drug effect....

The guidance of developing neurons to the right position in the central nervous system is of central importance in brain development. TRPC channels are thought to mediate turning responses of growth cones to guidance cues through fine control of calcium transients. Proliferating and 1-5 days differentiated neural progenitor cells (NPCs) showed expr...

Background: Local acidosis has been demonstrated in ischemic tissues and at inflammatory sites. Results: Acidic extracellular pH triggers NLRP3 inflammasome activation and interleukin-1β secretion in human macrophages. Conclusion: Acidic pH represents a novel danger signal alerting the innate immunity. Significance: Local acidosis may promot...

Neurotransmitters such as glutamate are potential regulators of neurogenesis. Interference with defined glutamate receptor subtypes affects proliferation, migration and differentiation of neural progenitor cells. The cellular targets for the actions of different glutamate receptor ligands are less well known. In this study we have combined calcium...

The central role of calcium influx and electrical activity in embryonic development raises important questions about the role and regulation of voltage dependent calcium influx. Using cultured neural progenitor cells (NPCs) preparations, we recorded barium currents through voltage activated channels using the whole cell configuration of the patch c...

Neurotrophins like brain-derived neurotrophic factor (BDNF) promote the migration of subsets of neural progenitor cells. The mechanism by which motility is increased and the functional properties of BDNF-responsive cells are not very well known. We have used the neurosphere model, combining time-lapse microscopy, immunocytochemistry, and Ca(2+) ima...

Extracellular acidification can occur in atherosclerotic lesions, specifically in areas with high numbers of metabolically active macrophages secreting lactate and hydrogen ions. There is a growing body of evidence showing that acidification of the extracellular environment causes fundamental changes in the functions of immune cells. Here we studie...

The response of differentiating mouse neural progenitor cells, migrating out from neurospheres, to conditions simulating ischemia (hypoxia and extracellular or intracellular acidosis) was studied. We show here, by using BCECF and single cell imaging to monitor intracellular pH (pH(i)), that two main populations can be distinguished by exposing migr...

Glutamate-responsive α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors are considered to play a significant role in neurogenesis. We have studied the functional expression of these receptors in migrating embryonic neural progenitor cells (NPCs). The majority of neurosphere-derived NPCs express AMPA receptors already during the f...

Osteoclasts are signaled by the bone matrix proteins fibronectin (FN), vitronectin (VN), and osteopontin (OPN) via integrins. To perform their resorptive function, osteoclasts cycle between compact (polarized), spread (non-resorbing) and migratory morphologies. Here we investigate the effects of matrix proteins on osteoclast morphology and how thos...

TRPC channels play significant roles in the regulation of neuronal plasticity and development. The mechanism by which these nonselective cation channels exert their trophic actions appears to involve entry of Ca2+ into the cells. Using a neuronal cell model (differentiated human IMR32 neuroblastoma cells), we demonstrate a central role for sodium e...

TRPA1 and TRPM8 are transient receptor potential (TRP) channels involved in sensory perception. TRPA1 is a non-selective calcium permeable channel activated by irritants and proalgesic agents. TRPM8 reacts to chemical cooling agents such as menthol. The human neuroblastoma cell line IMR-32 undergoes a remarkable differentiation in response to treat...

Culturing the human natural killer cell line NK-92 for 24 h in the presence of thymic stromal lymphopoietin (TSLP) potentiated its cytotoxic capacity against the erythroleukemia cell line K562. Longer incubation times did not augment the NK activity any further. No synergistic effects with respect to either proliferation or cytotoxicity were observ...

Ribonucleases are ubiquitous enzymes involved in RNA metabolism and are classified in several families on the basis of their structural, catalytic, and biological properties. Here, we describe characterization of the only human member of the Rh/T2/S family of acid hydrolases so far described, named RNASET2. This protein was previously reported to h...

Ascorbic acid (vitamin C) induced hydrogen peroxide (H(2)O(2)) formation was measured in household drinking water and metal supplemented Milli-Q water by using the FOX assay. Here we show that ascorbic acid readily induces H(2)O(2) formation in Cu(II) supplemented Milli-Q water and poorly buffered household drinking water. In contrast to Cu(II), ir...

The aim of this study was to evaluate whether iron, like copper, could support Vitamin C mediated hydroxyl radical formation in bicarbonate-rich water. By using the hydroxyl radical indicator coumarin-3-carboxylic acid, we found that iron, in contrast to copper, was not capable to support Vitamin C induced hydroxyl radical formation. However, when...

Two monoclonal antibodies, termed nnIE11 and nnIG11, were generated against the murine thymic stromal lymphopoietin receptor, mTSLPR, using traditional hybridoma technology. The antibody-producing hybridoma clones were obtained by fusing P3X63-Ag8.653 myeloma cells with splenocytes from Balb/c mice immunized with anti-FLAG M2 affinity-purified FLAG...

The gene encoding the murine thymic stromal lymphopoietin receptor was expressed in lepidopteran insect cells using the baculovirus expression vector system. The corresponding gene was inserted under the polyhedrin promoter of the Autographa californica Nuclear Polyhedrosis Virus and expressed with an N-terminal poly-histidine tag and a C-terminal...

We have previously shown that vitamin C (ascorbic acid) can initiate hydroxyl radical formation in copper contaminated household drinking water. In the present study, we have examined the stability of vitamin C in copper and bicarbonate containing household drinking water. In drinking water samples, contaminated with copper from the pipes and buffe...

We have previously shown that Vitamin C (ascorbic acid) can trigger hydroxyl radical formation in copper contaminated household drinking water. We report here that the capacity of ascorbic acid to catalyze hydroxyl radical generation in the drinking water samples is strongly dependent on the bicarbonate concentration (buffer capacity and pH) of the...

Ascorbic acid (vitamin C) induced hydroxyl radical formation was measured in household drinking water samples using the hydroxyl radical sensitive probe coumarin-3-carboxylic acid. Vitamin C, a reducing agent that is commonly used as a food additive, triggered a significant hydroxyl radical generating reaction when added to the tap-water samples te...

The presence of a soluble form of the common cytokine receptor gamma chain (gamma(c)) in cell free supernatants from unstimulated and 1-6 days PHA stimulated peripheral blood lymphocyte (PBL) cultures was analyzed using a sandwich ELISA. No naturally produced soluble gamma(c) could be detected in these cell free culture supernatants, although a sen...

The presence of a soluble form of the common cytokine receptor γ chain (γc) in cell free supernatants from unstimulated and 1–6 days PHA stimulated peripheral blood lymphocyte (PBL) cultures was analyzed using a sandwich ELISA. No naturally produced soluble γc could be detected in these cell free culture supernatants, although a sensitivity in the...

An assay named Cell TR-FRET based on time-resolved fluorescence resonance energy transfer, here utilized for detection of receptor proteins on intact cells, is described. In this assay, intact membrane-biotinylated Sf9 cells expressing human interleukin-2Rα due to infection with a recombinant baculovirus were prelabeled with a streptavidin–europium...

Monoclonal antibodies specific for the common cytokine receptor gamma chain, gammac, were produced using traditional hybridoma technology. Fusion of P3X63-Ag8.653 myeloma cells with splenocytes from Balb/c mice immunized with Spodoptera frugiperda insect cells infected with the recombinant baculovirus VL1392-hIL-2Rgamma resulted in several hybridom...

Monoclonal antibodies specific for the common cytokine receptor gamma chain, γc, were produced using traditional hybridoma technology. Fusion of P3X63-Ag8.653 myeloma cells with splenocytes from Balb/c mice immunized with Spodoptera frugiperda insect cells infected with the recombinant baculovirus VL1392-hIL-2Rγ resulted in several hybridoma cell c...

Phosphonoformic acid (foscarnet) is an antiviral agent that is used to treat severe cytomegalovirus infections in AIDS patients. We demonstrate by using the ferrous iron indicator Ferrozine and ascorbic acid (vitamin C) that foscarnet can chelate ferric iron and form a redox-active iron complex. By using the hydroxyl radical indicator coumarin-3-ca...

Phosphonoformic acid (foscarnet) is an antiviral agent that is used to treat severe cytomegalovirus infections in AIDS patients. We demonstrate by using the ferrous iron indicator Ferrozine and ascorbic acid (vitamin C) that foscarnet can chelate ferric iron and form a redox-active iron complex. By using the hydroxyl radical indicator coumarin-3-ca...

The baculovirus expression vector system (BEVS), utilizing the Autographa californica nuclear polyhedrosis virus (AcNPV), has turned out to be an attractive alternative for high-level expression (<600 mg/l) of recombinant proteins. However, there is a shortage of reliable methods for monitoring the infection process in situations where marker prote...

The gene encoding the green fluorescent protein (GFP) from the jellyfish Aequorea victoria, was inserted under transcriptional control of the polyhedrin promoter of the Autographa californica nuclear polyhedrosis virus and expressed in the Spodoptera frugiperda insect cell line Sf9 during viral infection. The baculovirus transfervector pBlueBacHisB...

A microplate-based fluorometric assay was developed for quantitation of cancer cell attachment to bone matrix. To evaluate this model system we used a panel of human cancer cell lines, including the human breast cancer cell line MDA-MB-231. For the assay, bovine cortical bone from the shaft of the femur was cut, turned, and sliced to 6-mm-diameter...

Molecular mechanisms involved in the rapid attachment of the human breast cancer cell line MDA-MD-231 to cortical bone matrix were studied. The attachment of MDA-MD-231 cells to cortical bone disks could be blocked by 75% when cells were pretreated with a monoclonal antibody to the beta1-subunit of the integrin family. Monoclonal antibodies against...

Molecular mechanisms involved in the rapid attachment of the human breast cancer cell line MDA-MD-231 to cortical bone matrix were studied, The attachment of MDA-MD-231 cells to cortical bone disks could be blocked by 75% when cells were pretreated with a monoclonal antibody to the beta(1)-subunit of the integrin family. Monoclonal antibodies again...

Proton extrusion into an extracellular resorption compartment is an essential component of bone degradation by osteoclasts. Chronic metabolic acidosis is known to induce negative calcium balance and bone loss by stimulating osteoclastic bone resorption, but the underlying mechanism is not known. The present studies were undertaken to evaluate wheth...

Proton pump activity is not measurable in the plasma membrane of unstimulated neutrophils but becomes readily detectable upon activation by soluble agonists. The mechanism of pump activation was investigated in this report. V-type H+ pump activity, estimated as a bafilomycin A1-sensitive elevation of the cytosolic pH, was stimulated in suspended ne...

Maintenance of cytoplasmic pH (pHi) within a narrow physiological range is crucial to normal cellular function. This is of particular relevance to phagocytic cells within the acidic inflammatory microenvironment where the pHi tends to be acid loaded. We have previously reported that a vacuolar-type H(+)-ATPase (V-ATPase) situated in the plasma memb...

Osteoclasts resorb bone by secreting protons into an extracellular resorption zone through vacuolar-type proton pumps located in the ruffled border. The present study was undertaken to evaluate whether proton pumps also contribute to intracellular pH (pHi) regulation. Fluorescence imaging and photometry, and electrophysiological methods were used t...

We have established three lymphoma cell lines, HF-1 from one follicular lymphoma (FL) patient, and HF-4 and HF-9 from another. All cell lines carry the characteristic t(14;18) chromosomal translocation and express constitutively the bcl-2 gene product (Bcl-2 protein). Cross-linking of their surface membrane Igs (sigs) with relevant antibodies trigg...

The role of protein kinase C in the regulation of vacuolar-type H(+)-ATPase (V-ATPase) activity was studied in thioglycolate-elicited mouse peritoneal macrophages. Acid-loaded macrophages suspended in a Na(+)- and HCO(3-)-free K(+)-medium containing Zn2+, a H(+)-conductance blocker, exhibited an initial intracellular pH recovery rate of 0.33 +/- 0....

Maintenance of cytoplasmic pH (pHi) close to the physiologic range is vital to normal cellular homeostasis. We have previously reported that a vacuolar-type H(+)-adenosine triphosphatase (V-ATPase) situated in the plasma membrane of macrophages and poised to extrude protons from the cytoplasmic to the extracellular space is an important pHi regulat...

The effect of SK&F 96365 (1-(beta-[3-(4-methoxyphenyl)propoxyl]-4- methoxyphenethyl)-1H-imidazole hydrochloride), a recently synthesized inhibitor of receptor-mediated calcium entry, was investigated on human hematopoietic cell lines. We found that treatment of the T-cell leukemia line Jurkat with SK&F 96365 inhibited the Ca2+ influx triggered by a...

The role of elevated intracellular calcium concentration [Ca2+]i in the LPS-induced activation of interleukin-1 beta (IL-1 beta) production was examined in cells representing different stages of myeloid differentiation (undifferentiated monocytic leukaemia cell line THP-1, THP-1 cells induced to adherent, macrophage-like cells by phorbol ester trea...

Treatment of T lymphocytes with mitogenic antibodies against the T-cell receptor/CD3 complex induces within seconds a rise in the concentration of intracellular free Ca2+. We recently reported that free myristic acid, but not its methyl ester, inhibits both the anti-CD3-induced Ca2+ influx across the cell membrane and the Ca2+ release from intracel...

Data that support a differential regulation of the interleukin-2 receptor (IL-2R) alpha-(p55 or Tac) and beta-chain (p70) expression by IL-4 are presented. Cytofluorometric analysis performed on peripheral blood mononuclear cells, some of which had been nylon wool passed (enriched for T-cells), in the presence or absence of phytohemagglutinin (PHA)...

Stimulation of T lymphocytes with antibodies against the T cell receptor/CD3 complex induces within seconds a rise in the concentration of intracellular free Ca2+. Here we show that treatment with 20 microM free myristic acid completely inhibits this Ca2+ signal and the cellular proliferation in Jurkat T cells. Also lauric acid inhibited cell growt...

We have earlier reported changes in the GTP binding of several membrane proteins including Gsα and Giα during thymic differentiation of T cells. Using an [α-32P]GTP-photoaffinity labeling technique we have studied the pattern of GTP binding proteins in activated and resting T lymphocytes and in T cells induced to differentiate by TPA. The GTP bindi...

Stimulation of Jurkat T cells with antibodies against the T cell receptor/CD3 complex induces a rise in the intracellular concentration of Ca2+ within seconds. The inositol phosphate-dependent Ca2+ mobilization induced by OKT3 was completely abrogated when Jurkat cells were pretreated for 1 min with the phorbol 12-myristate 13-acetate TPA (10nM), a...

We have investigated the effect of cAMP concentration on the CD3-mediated rise in intracellular Ca2+ induced by anti-CD3 monoclonal antibody in the human T cell leukemia line Jurkat. Forskolin, prostaglandin E2 (PGE2) and dibutyryl cAMP (db-cAMP) were used to increase intracellular cAMP concentrations. Treatment of Jurkat cells with forskolin or db...