Altered connexin expression and wound healing in the epidermis of connexin-deficient mice.
AuthorsKretz M, Euwens C, Hombach S, Eckardt D, Teubner B, Traub O, Willecke K, Ott T
JournalJ Cell Sci
PubMed ID12840073
'To analyze the effect of connexin loss on the repair of wounded tail skin, we have studied the following transgenic mouse mutants: connexin30-/-, connexin31-/- and connexin43Cre-ER(T)/fl (for inducible deletion of the connexin43 coding region). Connexin43 and connexin31 are expressed in the basal and spinous layers of wild-type epidermis, whereas connexin31 ... More
Gap junctional communication in the early Xenopus embryo.
AuthorsLandesman Y, Goodenough DA, Paul DL
JournalJ Cell Biol
PubMed ID10953017
'In the Xenopus embryo, blastomeres are joined by gap junctions that allow the movement of small molecules between neighboring cells. Previous studies using Lucifer yellow (LY) have reported asymmetries in the patterns of junctional communication suggesting involvement in dorso-ventral patterning. To explore that relationship, we systematically compared the transfer of ... More
Characterization of a synaptiform transmission between a neuron and a glial cell in the leech central nervous system.
AuthorsBritz FC, Lohr C, Schmidt J, Deitmer JW
JournalGlia
PubMed ID11968059
'The cross-talk between neurons and glial cells is receiving increased attention because of its potential role in information processing in nervous systems. Stimulation of a single identifiable neuron, the neurosecretory Leydig interneuron in segmental ganglia of the leech Hirudo medicinalis, which modulates specific behaviors in the leech, evokes membrane hyperpolarization ... More
Quantitative analysis of gap-junctional intercellular communication in precision-cut mouse liver slices.
AuthorsRomualdi A, Niessen H, Dombrowski F, Willecke K, Ott T
JournalCell Tissue Res
PubMed ID11904767
'Direct intercellular communication through gap junction channels is involved in the maintenance of tissue homeostasis and suppression of carcinogenesis. Gap-junctional communication is often altered in tumor cells but it can also be modulated in response to tumor promotors or inflammatory signals. In order to evaluate the effect of nongenotoxic compounds, ... More
Long-term stimulation of mouse hippocampal slice culture on microelectrode array.
Authorsvan Bergen A, Papanikolaou T, Schuker A, Möller A, Schlosshauer B
JournalBrain Res Brain Res Protoc
PubMed ID12738008
'To understand mechanisms of information processing, development and degeneration of the central nervous system, simultaneous multisite recording and stimulation have become extremely helpful. We have further developed the innovative approach to record from intact neural networks using planar microelectrode arrays (MEAs) with 60 substrate-integrated nano-columnar electrodes. To allow for long-term ... More
T-type Ca(2+) channels mediate neurotransmitter release in retinal bipolar cells.
AuthorsPan ZH, Hu HJ, Perring P, Andrade R
JournalNeuron
PubMed ID11604141
'Transmitter release in neurons is thought to be mediated exclusively by high-voltage-activated (HVA) Ca(2+) channels. However, we now report that, in retinal bipolar cells, low-voltage-activated (LVA) Ca(2+) channels also mediate neurotransmitter release. Bipolar cells are specialized neurons that release neurotransmitter in response to graded depolarizations. Here we show that these ... More
Saposin C is required for lipid presentation by human CD1b.
AuthorsWinau F, Schwierzeck V, Hurwitz R, Remmel N, Sieling PA, Modlin RL, Porcelli SA, Brinkmann V, Sugita M, Sandhoff K, Kaufmann SH, Schaible UE
JournalNat Immunol
PubMed ID14716313
'Lipids from Mycobacterium tuberculosis are presented through CD1 proteins to T lymphocytes in humans, but the accessory molecules required for antigen loading and presentation remain unidentified. Here we show that fibroblasts deficient in sphingolipid activator proteins (SAPs) transfected with CD1b failed to activate lipid-specific T cells. However, the T cell ... More
Protein-heparin interactions measured by BIAcore 2000 are affected by the method of heparin immobilization.
AuthorsOsmond RI, Kett WC, Skett SE, Coombe DR
JournalAnal Biochem
PubMed ID12423639
'Surface plasmon resonance (SPR) biosensors such as the BIAcore 2000 are a useful tool for the analysis of protein-heparin interactions. Generally, biotinylated heparin is captured on a streptavidin-coated surface to create heparinized surfaces for subsequent binding analyses. In this study we investigated three commonly used techniques for the biotinylation of ... More
Bipolar cells use kainate and AMPA receptors to filter visual information into separate channels.
AuthorsDeVries SH
JournalNeuron
PubMed ID11163271
Unlike cone photoreceptors, whose light responses have a uniform time course, retinal ganglion cells are tuned to respond to different temporal components in a changing visual scene. The signals in a mammalian cone flow to three to five morphologically distinct "OFF" bipolar cells at a sign-conserving, glutamatergic synapse. By recording ... More
Transformation of olfactory representations in the Drosophila antennal lobe.
AuthorsWilson RI, Turner GC, Laurent G
JournalScience
PubMed ID14684826
Molecular genetics has revealed a precise stereotypy in the projection of primary olfactory sensory neurons onto secondary neurons. A major challenge is to understand how this mapping translates into odor responses in these second-order neurons. We investigated this question in Drosophila using whole-cell recordings in vivo. We observe that monomolecular ... More
Monitoring presynaptic calcium dynamics in projection fibers by in vivo loading of a novel calcium indicator.
AuthorsKreitzer AC, Gee KR, Archer EA, Regehr WG
JournalNeuron
PubMed ID10939328
Fluorometric calcium measurements have revealed presynaptic residual calcium (Ca(res)) to be an important regulator of synaptic strength. However, in the mammalian brain, it has not been possible to monitor Ca(res) in fibers that project from one brain region to another. Here, we label neuronal projections by injecting dextran-conjugated calcium indicators ... More
High-content, high-throughput analysis of cell cycle perturbations induced by the HSP90 inhibitor XL888.
AuthorsLyman SK, Crawley SC, Gong R, Adamkewicz JI, McGrath G, Chew JY, Choi J, Holst CR, Goon LH, Detmer SA, Vaclavikova J, Gerritsen ME, Blake RA,
JournalPLoS One
PubMed ID21408192
Many proteins that are dysregulated or mutated in cancer cells rely on the molecular chaperone HSP90 for their proper folding and activity, which has led to considerable interest in HSP90 as a cancer drug target. The diverse array of HSP90 client proteins encompasses oncogenic drivers, cell cycle components, and a ... More
Light-directed electrical stimulation of neurons cultured on silicon wafers.
AuthorsStarovoytov A, Choi J, Seung HS
JournalJ Neurophysiol
PubMed ID15385589
Dissociated neurons cultured in vitro can serve as a model system for studying the dynamics of neural networks. Such studies depend on techniques for stimulating patterns of neural activity. We show a technique for extracellular stimulation of dissociated neurons cultured on silicon wafers. When the silicon surface is reverse biased, ... More
The spine neck filters membrane potentials.
AuthorsAraya R, Jiang J, Eisenthal KB, Yuste R
JournalProc Natl Acad Sci U S A
PubMed ID17093040
Dendritic spines receive most synaptic inputs in the forebrain. Their morphology, with a spine head isolated from the dendrite by a slender neck, indicates a potential role in isolating inputs. Indeed, biochemical compartmentalization occurs at spine heads because of the diffusional bottleneck created by the spine neck. Here we investigate ... More
Lipopolysaccharide (LPS) labeled with Alexa 488 hydrazide as a novel probe for LPS binding studies.
AuthorsTriantafilou K, Triantafilou M, Fernandez N
JournalCytometry
PubMed ID11084617
BACKGROUND: Lipopolysaccharide (LPS) comprises the outer cell wall of all gram-negative bacteria. It consists of an oligosaccharide core and lipid A. All LPS-induced biological responses are lipid A-dependent. Once released, LPS triggers a host systemic inflammatory response that leads to septic shock. Binding studies have helped to reveal some of ... More
Two phases of zymogen granule lifetime in mouse pancreas: ghost granules linger after exocytosis of contents.
AuthorsThorn P, Parker I
JournalJ Physiol
PubMed ID15637100
Different cell types show widely divergent mechanisms and kinetics of exocytosis. We investigated these processes in pancreatic acinar cells by using video-rate 2-photon microscopy to image entry of extracellular dye into individual zymogen granules undergoing exocytosis. Fluorescence signals display two distinct phases; an initial peak that then decays over several ... More
Detecting and quantifying colocalization of cell surface molecules by single particle fluorescence imaging.
AuthorsMorrison IE, Karakikes I, Barber RE, Fernández N, Cherry RJ
JournalBiophys J
PubMed ID14645098
Single particle fluorescence imaging (SPFI) uses the high sensitivity of fluorescence to visualize individual molecules that have been selectively labeled with small fluorescent particles. The positions of particles are determined by fitting the intensity profile of their images to a 2-D Gaussian function. We have exploited the positional information obtained ... More
Folding of A+U-rich RNA elements modulates AUF1 binding. Potential roles in regulation of mRNA turnover.
AuthorsWilson GM, Sutphen K, Chuang Ky Brewer G
JournalJ Biol Chem
PubMed ID11124962
In mammals, A+U-rich elements (AREs) are potent cis-acting determinants of rapid cytoplasmic mRNA turnover. Recognition of these sequences by AUF1 is associated with acceleration of mRNA decay, likely involving recruitment or assembly of multi-subunit trans-acting complexes. Previously, we demonstrated that AUF1 deletion mutants formed tetramers on U-rich RNA substrates by ... More
Modulation of antigen presentation by autoreactive B cell clones specific for GAD65 from a type I diabetic patient.
AuthorsBanga JP, Moore JK, Duhindan N, Madec AM, van Endert PM, Orgiazzi J, Endl J
JournalClin Exp Immunol
PubMed ID14678267
We used a GAD65-specific human B-T cell line cognate system in vitro to investigate the modulation of GAD65 presentation by autoantibody, assessed in a proliferation assay. Generally, if the T cell determinant overlaps or resides within the antibody epitope, effects of presentation are blunted while if they are distant can ... More
Fluid-phase endocytosis does not contribute to rapid fluid secretion in the malpighian tubules of the house cricket, Acheta domesticus.
AuthorsHazelton SR, Spring JH, Felgenhauer BE
JournalJ Exp Zool
PubMed ID11754017
When the Malpighian tubules (Mt) of the house cricket (Acheta domesticus) are treated with dibutyryl adenosine 3', 5'-cyclic monophosphate (db-cAMP; 1 mM), which causes a doubling in secretion rate, more than 50% of the cell volume is occupied by vesicles within 420 sec of exposure. In view of the fact ... More
Quantitative comparisons of corticothalamic topography within the ventrobasal complex and the posterior nucleus of the rodent thalamus.
AuthorsAlloway KD, Hoffer ZS, Hoover JE
JournalBrain Res
PubMed ID12644264
To compare the topographic precision of corticothalamic projections to the ventrobasal (VB) complex and the medial part of the posterior (POm) complex, different anterograde tracers were placed in neighboring parts of the primary (SI) and secondary (SII) somatosensory cortical areas. The location of labeled corticothalamic terminals and their beaded varicosities ... More
The permeability of gap junction channels to probes of different size is dependent on connexin composition and permeant-pore affinities.
Gap junctions have traditionally been characterized as nonspecific pores between cells passing molecules up to 1 kDa in molecular mass. Nonetheless, it has become increasingly evident that different members of the connexin (Cx) family mediate quite distinct physiological processes and are often not interchangeable. Consistent with this observation, differences in ... More
A transient diffusion model yields unitary gap junctional permeabilities from images of cell-to-cell fluorescent dye transfer between Xenopus oocytes.
As ubiquitous conduits for intercellular transport and communication, gap junctional pores have been the subject of numerous investigations aimed at elucidating the molecular mechanisms underlying permeability and selectivity. Dye transfer studies provide a broadly useful means of detecting coupling and assessing these properties. However, given evidence for selective permeability of ... More
Dendritic compartmentalization of chloride cotransporters underlies directional responses of starburst amacrine cells in retina.
AuthorsGavrikov KE, Nilson JE, Dmitriev AV, Zucker CL, Mangel SC
JournalProc Natl Acad Sci U S A
PubMed ID17124178
The mechanisms in the retina that generate light responses selective for the direction of image motion remain unresolved. Recent evidence indicates that directionally selective light responses occur first in the retina in the dendrites of an interneuron, i.e., the starburst amacrine cell, and that these responses are highly sensitive to ... More
Conductance and permeability of the residual state of connexin43 gap junction channels.
AuthorsBukauskas FF, Bukauskiene A, Verselis VK
JournalJ Gen Physiol
PubMed ID11815667
We used cell lines expressing wild-type connexin43 and connexin43 fused with the enhanced green fluorescent protein (Cx43-EGFP) to examine conductance and perm-selectivity of the residual state of Cx43 homotypic and Cx43/Cx43-EGFP heterotypic gap junction channels. Each hemichannel in Cx43 cell-cell channel possesses two gates: a fast gate that closes channels ... More
Quality control procedures for dose-response curve generation using nanoliter dispense technologies.
AuthorsQuintero C, Rosenstein C, Hughes B, Middleton R, Kariv I
JournalJ Biomol Screen
PubMed ID17517899
With the advancement of high-throughput biomolecular screening techniques to the lead optimization stage, there is a critical need to quality control (QC) dose-response curves generated by robotic liquid handlers to ensure accurate affinity determinations. One challenge in evaluating the performance of liquid handlers is identifying and validating a robust method ... More
Permeability and gating properties of human connexins 26 and 30 expressed in HeLa cells.
AuthorsBeltramello M, Bicego M, Piazza V, Ciubotaru CD, Mammano F, D'Andrea P
JournalBiochem Biophys Res Commun
PubMed ID12767933
Human connexins 26 and 30 were expressed either through the bicistronic pIRES-EGFP expression vector or as EYFP-tagged chimeras. When transiently transfected in communication-incompetent HeLa cells, hCx26-pIRES transfectants were permeable to dyes up to 622 Da, but were significantly less permeable to 759 Da molecules. Under the same conditions, permeability of ... More
Mutation of a conserved threonine in the third transmembrane helix of alpha- and beta-connexins creates a dominant-negative closed gap junction channel.
AuthorsBeahm DL, Oshima A, Gaietta GM, Hand GM, Smock AE, Zucker SN, Toloue MM, Chandrasekhar A, Nicholson BJ, Sosinsky GE
JournalJ Biol Chem
PubMed ID16407179
Single site mutations in connexins have provided insights about the influence specific amino acids have on gap junction synthesis, assembly, trafficking, and functionality. We have discovered a single point mutation that eliminates functionality without interfering with gap junction formation. The mutation occurs at a threonine residue located near the cytoplasmic ... More
Endocannabinoid-independent retrograde signaling at inhibitory synapses in layer 2/3 of neocortex: involvement of vesicular glutamate transporter 3.
Recent studies implicate dendritic endocannabinoid release from subsynaptic dendrites and subsequent inhibition of neurotransmitter release from nerve terminals as a means of retrograde signaling in multiple brain regions. Here we show that type 1 cannabinoid receptor-mediated endocannabinoid signaling is not involved in the retrograde control of synaptic efficacy at inhibitory ... More
Intracellular pathways regulating ciliary beating of rat brain ependymal cells.
AuthorsNguyen T, Chin WC, O'Brien JA, Verdugo P, Berger AJ
JournalJ Physiol
PubMed ID11179397
1. The mammalian brain ventricles are lined with ciliated ependymal cells. As yet little is known about the mechanisms by which neurotransmitters regulate cilia beat frequency (CBF). 2. Application of 5-HT to ependymal cells in cultured rat brainstem slices caused CBF to increase. 5-HT had an EC50 of 30 microM ... More
Calcium influx into dendrites of the leech Retzius neuron evoked by 5-hydroxytryptamine.
AuthorsBeck A, Lohr C, Berthold H, Deitmer JW
JournalCell Calcium
PubMed ID12027387
5-Hydroxytryptamine (5-HT) is a ubiquitous neurotransmitter and neuromodulator that affects neural circuits and behaviours in vertebrates and invertebrates. In the present study, we have investigated 5-HT-induced Ca(2+) transients in subcellular compartments of Retzius neurons in the leech central nervous system using confocal laser scanning microscopy, and studied the effect of ... More