Publications by authors named "Eleni Roussa"

Mutations in LRBA, a BEACH domain protein, cause severe immune deficiency in humans. LRBA is expressed in many tissues and organs according to biochemical analysis, but little is known about its cellular and subcellular localization, and its deficiency phenotype outside the immune system. By LacZ histochemistry of Lrba gene-trap mice, we performed a comprehensive survey of LRBA expression in numerous tissues, detecting it in many if not all epithelia, in exocrine and endocrine cells, and in subpopulations of neurons.

View Article and Find Full Text PDF

Ischemic conditions cause an increase in the sodium concentration of astrocytes, driving the breakdown of ionic homeostasis and exacerbating cellular damage. Astrocytes express high levels of the electrogenic sodium-bicarbonate cotransporter1 (NBCe1), which couples intracellular Na homeostasis to regulation of pH and operates close to its reversal potential under physiological conditions. Here, we analyzed its mode of operation during transient energy deprivation via imaging astrocytic pH, Na, and ATP in organotypic slice cultures of the mouse neocortex, complemented with patch-clamp and ion-selective microelectrode recordings and computational modeling.

View Article and Find Full Text PDF

K/Cl cotransporter 2 (KCC2) is a major Cl extruder in mature neurons and is responsible for the establishment of low intracellular [Cl], necessary for fast hyperpolarizing GABA-receptor mediated synaptic inhibition. Electrogenic sodium bicarbonate cotransporter 1 (NBCe1) is a pH regulatory protein expressed in neurons and glial cells. An interactome study identified NBCe1 as a possible interaction partner of KCC2.

View Article and Find Full Text PDF

The transmembrane protein SLC22A17 [or the neutrophil gelatinase-associated lipocalin/lipocalin-2 (LCN2)/24p3 receptor] is an atypical member of the SLC22 family of organic anion and cation transporters: it does not carry typical substrates of SLC22 transporters but mediates receptor-mediated endocytosis (RME) of LCN2. One important task of the kidney is the prevention of urinary loss of proteins filtered by the glomerulus by bulk reabsorption of multiple ligands via megalin:cubilin:amnionless-mediated endocytosis in the proximal tubule (PT). Accordingly, overflow, glomerular, or PT damage, as in Fanconi syndrome, results in proteinuria.

View Article and Find Full Text PDF

KCC2 mediates extrusion of K and Cl and assuresthe developmental "switch" in GABA function during neuronal maturation. However, the molecular mechanisms underlying KCC2 regulation are not fully elucidated. We investigated the impact of transforming growth factor beta 2 (TGF-β2) on KCC2 during neuronal maturation using quantitative RT-PCR, immunoblotting, immunofluorescence and chromatin immunoprecipitation in primary mouse hippocampal neurons and brain tissue from -deficient mice.

View Article and Find Full Text PDF

Glioblastoma multiforme (GBM) is the most common and malignant brain tumour. It is characterised by transcriptionally distinct cell populations. In tumour cells, physiological pH gradients between the intracellular and extracellular compartments are reversed, compared to non-cancer cells.

View Article and Find Full Text PDF

Permanent degeneration and loss of dopaminergic (DA) neurons in substantia nigra is the main cause of Parkinson's disease. Considering the therapeutic application of stem cells in neurodegeneration, we sought to examine the neurogenic differentiation potential of the newly introduced neural crest originated mesenchymal stem cells (MSCs), namely, trabecular meshwork-derived mesenchymal stem cells (TM-MSCs) compared to two other sources of MSCs, adipose tissue-derived stem cells (ADSCs) and bone marrow-derived mesenchymal stem cells (BM-MSCs). The three types of cells were therefore cultured in the presence and absence of a neural induction medium followed by the analysis of their differentiation potentials.

View Article and Find Full Text PDF

Astrocytes are pivotal responders to alterations of extracellular pH, primarily by regulation of their principal acid-base transporter, the membrane-bound electrogenic Na /bicarbonate cotransporter 1 (NBCe1). Here, we describe amammalian target of rapamycin (mTOR)-dependent and NBCe1-mediated astroglial response to extracellular acidosis. Using primary mouse cortical astrocytes, we investigated the effect of long-term extracellular metabolic acidosis on regulation of NBCe1 and elucidated the underlying molecular mechanisms by immunoblotting, biotinylation of surface proteins, intracellular H recording using the H -sensitive dye 2',7'-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein, and phosphoproteomic analysis.

View Article and Find Full Text PDF

The liver hormone hepcidin regulates systemic iron homeostasis. Hepcidin is also expressed by the kidney, but exclusively in distal nephron segments. Several studies suggest hepcidin protects against kidney damage involving Fe overload.

View Article and Find Full Text PDF

The electrogenic Na /HCO cotransporter (NBCe1) in astrocytes is crucial in regulation of acid-base homeostasis in the brain. Since many pathophysiological conditions in the brain have been associated with pH shifts we exposed primary mouse cortical and hippocampal astrocytes to prolonged low or high extracellular pH (pH ) at constant extracellular bicarbonate concentration and investigated activation of astrocytes and regulation of NBCe1 by immunoblotting, biotinylation of surface proteins, and intracellular H recordings. High pH at constant extracellular bicarbonate caused upregulation of NBCe1 protein, surface expression and activity via upregulation of the astrocytic activation markers signal transducer and activator of transcription 3 (STAT3) signaling and glial fibrillary acidic protein expression.

View Article and Find Full Text PDF

Calcium homeostasis is a cellular process required for proper cell function and survival, maintained by the coordinated action of several transporters, among them members of the Na/Ca-exchanger family, such as SLC8A3. Transforming growth factor beta (TGF-β) signaling defines neuronal development and survival and may regulate the expression of channels and transporters. We investigated the regulation of SLC8A3 by TGF-β in a conditional knockout mouse with deletion of TGF-β signaling from Engrailed 1-expressing cells, i.

View Article and Find Full Text PDF

So far no evidence is available as to whether TGFβ and Wnt signaling pathways cooperatively modulate dopaminergic differentiation of the adult stem cells. To investigate the interaction between the two pathways in early dopaminergic differentiation, we cultured the newly introduced unrestricted somatic stem cells (USSCs) in neuron differentiation media followed by treatments with inducers and inhibitors of Wnt and TGF beta pathways either alone or in combinations. Our results showed that the level of Nurr-1 as a marker for dopaminergic neuron precursors and that of the nuclear β-catenin as the key effector of the active Wnt pathway were significantly elevated following the treatment with either TGFβ or BIO (the Wnt pathway inducer).

View Article and Find Full Text PDF

Transforming growth factor betas are integral molecular components of the signalling cascades defining development and survival of several neuronal groups. Among TGF-β ligands, TGF-β2 has been considered as relatively more important during development. We have generated a conditional knockout mouse of the gene with knock-in of an EGFP reporter and subsequently a mouse line with cell-type specific deletion of TGF-β2 ligand from Krox20 expressing cells (i.

View Article and Find Full Text PDF

The electrogenic sodium bicarbonate cotransporter 1, NBCe1 (SLC4A4), is the major bicarbonate transporter expressed in astrocytes. It is highly sensitive for bicarbonate and the main regulator of intracellular, extracellular, and synaptic pH, thereby modulating neuronal excitability. However, despite these essential functions, the molecular mechanisms underlying NBCe1-mediated astrocytic response to extracellular pH changes are mostly unknown.

View Article and Find Full Text PDF

Bicarbonate concentration in saliva is controlled by the action of acid-base transporters in salivary duct cells. We show for the first time expression of ATP6V1B1 in submandibular gland and introduce transforming growth factor-beta (TGF-β) as a novel regulator of V-ATPase subunits. Using QRT-PCR, immunoblotting, biotinylation of surface proteins, immunofluorescence, chromatin immunoprecipitation, and intracellular H( ) recording with H( )-sensitive dye 2',7'-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein we show that in the human submandibular gland (HSG) cell line, activation of TGF-β signaling upregulates ATP6V1E1 and ATP6V1B2, downregulates ATP6V1B1, and has no effect on ATP6V1A.

View Article and Find Full Text PDF

Molecular and functional diversity within midbrain dopaminergic (mDA) and hindbrain serotonergic (5-HT) neurons has emerged as a relevant feature that could underlie selective vulnerability of neurons in clinical disorders. We have investigated the role of transforming growth factor beta (TGF-β) during development of mDA and 5-HT subgroups. We have generated TβRII::En1 mice where type II TGF-β receptor is conditionally deleted from engrailed 1-expressing cells and have investigated the hindbrain serotonergic system of these mice together with Tgf-β2 mice.

View Article and Find Full Text PDF

The optic fissure is a transient gap in the developing vertebrate eye, which must be closed as development proceeds. A persisting optic fissure, coloboma, is a major cause for blindness in children. Although many genes have been linked to coloboma, the process of optic fissure fusion is still little appreciated, especially on a molecular level.

View Article and Find Full Text PDF

The temporal dynamic expression of Sonic Hedgehog (SHH) and signaling during early midbrain dopaminergic (mDA) neuron development is one of the key players in establishing mDA progenitor diversity. However, whether SHH signaling is also required during later developmental stages and in mature mDA neurons is less understood. We study the expression of SHH receptors Ptch1 and Gas1 (growth arrest-specific 1) and of the transcription factors Gli1, Gli2 and Gli3 in mouse midbrain during embryonic development [embryonic day (E) 12.

View Article and Find Full Text PDF

The electrogenic sodium bicarbonate cotransporter NBCe1 (SLC4A4) expressed in astrocytes regulates intracellular and extracellular pH. Here, we introduce transforming growth factor beta (TGF-β) as a novel regulator of NBCe1 transcription and functional expression. Using hippocampal slices and primary hippocampal and cortical astrocyte cultures, we investigated regulation of NBCe1 and elucidated the underlying signaling pathways by RT-PCR, immunoblotting, immunofluorescence, intracellular H( ) recording using the H( ) -sensitive dye 2',7'-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein, mink lung epithelial cell (MLEC) assay, and chromatin immunoprecipitation.

View Article and Find Full Text PDF

Introduction: The aim of this study was to elucidate whether the use of mineral trioxide aggregate (MTA) in endodontic therapy in human teeth leads to the same regeneration of the apical tissues as observed in animals.

Methods: Four human teeth were identified in a policlinic that had been treated endodontically with MTA and had to be extracted for other reasons than just endodontic failure. All teeth were processed for histologic and one for immunohistochemical analyses to analyze the histologic response of the periapical structure to the former treatment with MTA.

View Article and Find Full Text PDF

The human small heat shock proteins (HSPBs) form a family of molecular chaperones comprising ten members (HSPB1-HSPB10), whose functions span from protein quality control to cytoskeletal dynamics and cell death control. Mutations in HSPBs can lead to human disease and particularly point mutations in HSPB1 and HSPB8 are known to lead to peripheral neuropathies. Recently, a missense mutation (R7S) in yet another member of this family, HSPB3, was found to cause an axonal motor neuropathy (distal hereditary motor neuropathy type 2C, dHMN2C).

View Article and Find Full Text PDF

Functional activation of the neuronal K(+)-Cl(-) co-transporter KCC2 (also known as SLC12A5) is a prerequisite for shifting GABAA responses from depolarizing to hyperpolarizing during development. Here, we introduce transforming growth factor β2 (TGF-β2) as a new regulator of KCC2 membrane trafficking and functional activation. TGF-β2 controls membrane trafficking, surface expression and activity of KCC2 in developing and mature mouse primary hippocampal neurons, as determined by immunoblotting, immunofluorescence, biotinylation of surface proteins and KCC2-mediated Cl(-) extrusion.

View Article and Find Full Text PDF

The electrogenic sodium bicarbonate cotransporter NBCe1 (SLC4A4) is expressed in many cell types and is a major regulator of intracellular, and extracellular pH. In astrocytes, membrane depolarization leads to intracellular alkalinization through the activation of NBCe1. However, the molecular mechanisms regulating functional expression of NBCe1 in astrocytes are largely unknown.

View Article and Find Full Text PDF

We investigated the distribution patterns of the extracellular matrix protein Reelin and of crucial Reelin signaling components in murine midbrain and striatum. The cellular distribution of the Reelin receptors VLDLr and ApoER2, the intracellular downstream mediator Dab1, and the alternative Reelin receptor APP were analyzed at embryonic day 16, at postnatal stage 15 (P15), and in 3-month-old mice. Reelin was expressed intracellularly and extracellularly in midbrain mesencephalic dopaminergic (mDA) neurons of newborns.

View Article and Find Full Text PDF

The lipocalin 2//NGAL/24p3 receptor (NGAL-R/24p3-R) is expressed in rodent distal nephron where it mediates protein endocytosis. The mechanisms of apical endocytosis and transcytosis of proteins and peptides in the intestine are poorly understood. In the present study, the expression and localization of rodent 24p3-R (r24p3-R) and human NGAL-R (hNGAL-R) was investigated in intestinal segments by immunofluorescence and confocal laser scanning microscopy, immunohistochemistry and immunoblotting.

View Article and Find Full Text PDF