368 research outputs found
The Cytoplasmic Domain of the RyR1 Foot is Sufficient for DHPR (Cav1.1) Organization into Tetrads
No full textA RyR1 construct that lacks the channel forming C-terminal residues but includes the entire cytoplasmic foot region (YFP-RyR11:4300) forms a stable tetrameric structure (H. Bichraoui et al., abstract this meeting), colocalizes with DHPRs at SR/plasmalemma junctions and retrogradely enhances peak DHPR currents when expressed in dyspedic (RyR1 null) myotubes (A. Polster et al., abstract this meeting). We tested the interaction of the expressed RyR11:4300 with DHPRs in dyspedic myotubes by examining the DHPR disposition using freeze-fracture. Normally DHPRs are targeted to junctional sites in the absence of RyR, but their organization into tetrads and the arrangement of tetrads in ordered arrays is strictly dependent on their link to arrays of tetrameric RyRs. Thus the disposition of DHPRs in freeze-fracture images provides direct information both on DHPR/RyR interaction and on the arrangement of RyRs. In dyspedic cells DHPR clusters at peripheral couplings in a loose, completely random arrangement. Cells expressing full-length RyR1 show more tightly clustered DHPRs and the presence of complete (4 elements) and incomplete (2-3 elements) tetrads that are aligned in an orthogonal array. Cells expressing the truncated RyR11:4300 show small well identifiable DHPR foci with closely spaced particles. Some but not all foci show clear grouping of DHPRs into complete tetrads and/or tetrads composed of only three elements, but the tetrads are not aligned into a orthogonal array. We conclude that similar to intact RyR1, RyR11:4300 forms homo-tetramers which can link to DHPRs and organize them into tetrads, but that the cytoplasmic RyR1 foot differs from full-length RyR1 in that it does not form orthogonal arrays. The related positioning of RyR11:4300 and DHPRs is necessary for the retrograde interaction between the two
Zebrafish KLF4 is essential for anterior mesendoderm/pre-polster differentiation and hatching
No full textGene knockout studies of Kruppel-like factors (KLFs) in mice have shown essential roles in organogenesis. A screen for KLF family members in zebrafish identified many KLFs. One of these, zebrafish KLF4 (zKLF4) is the homologue of neptune, a Xenopus laevis KLF. zKLF4 is expressed from approximately 80% epiboly a patch of dorsal/anterior mesendodermal cells called the pre-polster and, subsequently, in the polster and hatching gland. Here we investigate the function of zKLF4 using morpholino-based antisense oligonucleotides. Knockdown of zKLF4 resulted in complete absence of hatching gland formation and subsequent hatching in zebrafish. In addition, there was early knockdown of expression of the pre-polster/anterior mesendoderm markers CatL, cap1, and BMP4. These results indicate zKLF4 is expressed within the pre-polster, an early mesendodermal site, and that it plays a critical role in the differentiation of these cells into hatching gland cells
The shoelace book: a mathematical guide to the best (and worst) ways to lace your shoes
No full textCrisscross, zigzag, bowtie, devil, angel, or star: which are the longest, the shortest, the strongest, and the weakest lacings? Pondering the mathematics of shoelaces, the author paints a vivid picture of the simple, beautiful, and surprising characterizations of the most common shoelace patterns. The mathematics involved is an attractive mix of combinatorics and elementary calculus. This book will be enjoyed by mathematically minded people for as long as there are shoes to lace. Burkard Polster is a well-known mathematical juggler, magician, origami expert, bubble-master, shoelace charmer, a
Stac Proteins Suppress Calcium Dependent Inactivation of Neuronal L-Type Ca 2+ Channels
No full textStac protein (named for its SH3 and cysteine rich domains) was first identified in brain 20 years ago, and is currently known to exist in three isoforms with specific tissue expression profiles. Transcripts for Stac1 and Stac2 are found in the cerebellum, forebrain, and eye, whereas transcripts for Stac3 are found at high levels in skeletal muscle and at low levels in the same three neuronally rich regions. However, the neuronal functions of Stac have been little investigated. Here, we tested the effects of Stac on currents via neuronal high-voltage-activated Ca2+ channels expressed together with their auxiliary subunits (β2a, α2-δ1) in tsA201 cells. As described previously by others, we observed Ca2+ entry-dependent inactivation (CDI) for CaV1.2 and CaV1.3 (the predominant, neuronal L-type Ca2+ channels), and for the P/Q-type Ca2+ channel CaV2.1. CDI for CaV1.2 and CaV1.3 was suppressed almost completely by all three Stac isoforms, whereas CDI for CaV2.1 was not detectably altered. CDI is thought to depend on CaM constitutively bound to the CaV C-terminus, but based on co-expression of fluorescently tagged CaV1.2 and CaM, the Stac-caused suppression of CDI did not involve the loss of bound CaM. Expression of CaV1.2 without auxiliary subunits resulted in small amplitude currents. These small amplitude currents displayed CDI which was similar to that when β2a and α2-δ1 were also present, and which was suppressed by all three Stac isoforms. Thus, the Stac proteins appear to bind directly to CaV1.2 (and most likely to CaV1.3 as well) and to interfere with CDI without displacing CaM. Our results indicate that one likely function of neuronal Stac proteins is to tune Ca2+ entry via L-type channels. Supported by grants from NIH (AR052354 and AR070298) and MDA (176448) to KGB
Interaction between CaV2.1 and Junctophilin3/4 depends on the II-III loop of CaV2.1 and on the α-helical region of Junctophilin3/4
No full text: Neuronal Junctophilins (JPH3 and JPH4) form junctions between the endoplasmic reticulum (ER) and plasma membrane (PM) through their C-terminal transmembrane domain, which is embedded in the ER membrane, and N-terminal domain, which binds to the PM. JPHs also recruit and slow the inactivation of the voltage-gated Ca2+ channel CaV2.1. Here, we identified the domains responsible for CaV2.1/JPH interactions by co-expressing the isolated GFP-tagged CaV2.1 cytoplasmic domains with mCherry-tagged JPH3/4 in tsA201 cells. Among the CaV2.1 domains, only the II-III loop colocalized with JPH3 and JPH4 as well as with the TM truncated JPH3-ΔTM and JPH4-ΔTM constructs, which cannot form ER-PM junctions. Further fragmentation of the II-III loop showed that both JPH-ΔTM constructs colocalized with the proximal half of the loop containing the synprint domain, known to bind presynaptic proteins, but only JPH4-ΔTM colocalized with the distal half and only JPH4 slowed the inactivation of a CaV2.1 construct lacking most of the synprint region. JPH colocalization with the II-III loop persisted when JPH divergent and transmembrane domains were deleted but was lost when the α-helical domain was also removed. Swapping the α-helical domains between JPH3 and JPH4 led to a corresponding exchange in their ability to interact with the II-III loop distal segment. Thus, the α-helical domain appears necessary for JPH binding to the synprint-containing II-III loop half and for the differential binding of JPH3 and JPH4 to the loop distal half. Furthermore, the binding of JPH α-helical domain to the CaV2.1 II-III loop is essential for slowing CaV2.1 inactivation
Mitochondria in the nervous system: From health to disease, Part I
No full textIn Part I of this Special Issue on "Mitochondria in the Nervous System: From Health to Disease", the editors bring together contributions from experts in brain mitochondrial research to provide an up-to-date overview of mitochondrial functioning in physiology and pathology. The issue provides cutting edge reviews on classical areas of mitochondrial biology that include energy substrate utilization, calcium handling, mitochondria-endoplasmic reticulum communication, and cell death regulation. Additional reviews and original research articles touch upon key mitochondrial defects seen across multiple neurodegenerative conditions, including fragmentation, loss of respiratory capacity, calcium overload, elevated reactive oxygen species generation, perturbed NAD+ metabolism, altered protein acetylation, and compromised mitophagy. Emerging links between the genetics of neurodegenerative disorders and disruption in mitochondrial function are discussed, and a new mouse model of Complex I deficiency is described. Finally, novel ways to rescue mitochondrial structure and function in acute and chronic brain injury are explored. (C) 2017 Published by Elsevier Ltd
Epilepsie und Träume - Übereinstimmung von Kind- und Elternurteil
No full textSchlarb A, Christen R, Bien C, Polster T. Epilepsie und Träume - Übereinstimmung von Kind- und Elternurteil. In: Erler T, Paditz E, eds. Zeit Alter Schlaf. Aktuelle Kinderschlafmedizin 2018. Dresden: Kleanthes; 2018: 164-165
Von epileptischen Anfällen träumen? Epilepsie, Träume und Alpträume bei Kindern und Jugendlichen
No full textSchlarb A, Christen R, Bien C, Polster T. Von epileptischen Anfällen träumen? Epilepsie, Träume und Alpträume bei Kindern und Jugendlichen. In: Erler T, Paditz E, eds. Zeit Alter Schlaf. Aktuelle Kinderschlafmedizin 2018. Dresden: Kleanthes; 2018: 162-163
Stac Proteins Suppress Ca2+-Dependent Inactivation of Neuronal L-type Ca2+ Channels
No full textStac protein (named for its SH3-and cysteine-rich domains) was first identified in brain 20 years ago and is currently known to have three isoforms. Stac2, Stac1, and Stac3 transcripts are found at high, modest, and very low levels, respectively, in the cerebellum and forebrain, but their neuronal functions have been little investigated. Here, we tested the effects of Stac proteins on neuronal, high-voltage-activated Ca2+ channels. Overexpression of the three Stac isoforms eliminated Ca2+-dependent inactivation (CDI) ofL-type current in rat neonatal hippocampal neurons (sex unknown), but not CDI of non-L-type current. Using heterologous expression in tsA201 cells (together with β and α2-δ1 auxiliary subunits), we found that CDI for CaV1.2 and CaV1.3 (the predominant, neuronalL-type Ca2+ channels) was suppressed by all three Stac isoforms, whereas CDI for the P/Q channel, CaV2.1, was not. For CaV1.2, the inhibition of CDI by the Stac proteins appeared to involve their direct interaction with the channel’s C terminus. Within the Stac proteins, a weakly conserved segment containing ~100 residues and linking the structurally conserved PKC C1 and SH3_1 domains was sufficient to fully suppress CDI. The presence of CDI forL-type current in control neonatal neurons raised the possibility that endogenous Stac levels are low in these neurons and Western blotting indicated that the expression of Stac2 was substantially increased in adult forebrain and cerebellum compared with neonate. Together, our results indicate that one likely function of neuronal Stac proteins is to tune Ca2+ entry via neuronal L-type channels. © 2018 the authors
Ueber die Vereinigung der beiden evangelischen Kirchen : eine Predigt vor der ev. lutherischen Gemeinde zu Schmalkalden am 25sten Sonntage nach Trinitatis gehalten
No full textLayoutgetreues Digitalisat der Ausg.: Schmalkalden : Polster, 1836
Standort: Zentralbibliothek (000)
Signatur: VIII C 1047, fuckel
Bemerkungen: Sammlung: Hessische Predigten, E - F
(Hassiaca
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