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  • Localization of Cacna1s to ON bipolar dendritic tips requires mGluR6-related cascade elements. 24519419

    L-type voltage gated calcium channels in retina localize primarily at the presynaptic active zones of photoreceptors and bipolar cells where they modulate glutamate release. However, the pore forming subunit Cacna1s of certain L-type channels is also expressed postsynaptically at the tips of ON bipolar cell dendrites where it colocalizes with mGluR6, but has an unknown function. At these dendritic tips, the components of the mGluR6 signaling cascade cluster together in a macromolecular complex, and each one's localization often depends on that of the others. Thus, we explored if Cacna1s is part of the mGluR6 complex.We determined Cacna1s expression by PCR using an ON bipolar library, by Western blotting, and by standard immunohistochemistry.The PCR amplification confirmed expression of the transcript in ON bipolar cells, and Western blotting showed the expected bands. Immunostaining for Cacna1s was stronger in the dendritic tips of rod bipolar cells than in those of ON cone bipolar cells. This staining severely decreased in mice missing various mGluR6 cascade elements (Grm6(-/-), Gnao1(-/-), Gnb3(-/-), Gng13(-/-), and Trpm1(-/-)). During development, the ratio of the number of Cacna1s puncta to the number of presynaptic ribbons followed a sigmoidal pattern, rising rapidly from P13 to P17. The mGluR6 expression preceded that of Cacna1s and RGS11.Our results show that the localization and stability of Cacna1s depend on the expression of mGluR6 and its cascade components, and they suggest that Cacna1s is part of the mGluR6 complex. We hypothesize that Cacna1s contributes to light adaptation by permeating calcium.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB427
    Nombre del producto:
    Anti-Dihydropyridine-sensitive Calcium Channel α 1 Subunit Antibody, clone 1a

  • Calcium/calmodulin-dependent protein kinase II and calmodulin: regulators of the meiotic spindle in mouse eggs. 9882483

    Elevation of intracellular free calcium causes egg activation by initiating a cascade of interacting signaling pathways that, in unison, act to remodel the cytoplasmic compartment and the nuclear compartment of the egg. We show here that calcium/calmodulin-dependent protein kinase II (CaM kinase II) is tightly associated with the meiotic spindle and that 5 min after egg activation there is a transient, tight association of calmodulin (colocalized with CaM kinase II) on the meiotic spindle. These correlative observations caused us to test whether activation of CaM kinase II mediated the chromosomal transit into an anaphase configuration. We demonstrate that calcium and calmodulin, at physiological levels, along with ATP were capable of driving the spindle (with its associated CaM kinase II) into an anaphase configuration in a permeabilized egg system. The transit into anaphase was dependent on the presence of both calcium and calmodulin and occurred normally when they were present at a ratio of 4 to 1. Peptide and pharmacologic inhibitors of CaM kinase II blocked the transit into anaphase, both in the permeabilized egg system and in living eggs (inhibitors of protein kinase C did not block the transit into anaphase). Using a biochemical approach we confirm that CaM kinase II increases in activity 5 min after egg activation and that a second increase occurs 45 min after activation at the approximate time that the contractile ring of the second polar body is constricting. This corresponds to the approximate time when calmodulin and CaM kinase II colocalize at several points in the activated egg including the region containing midzone microtubules. CaM kinase II appears localized on midzone microtubules as soon as they form and may have a role in specifying the position of the contractile ring of the second polar body.
    Tipo de documento:
    Referencia
    Referencia del producto:
    05-173
    Nombre del producto:
    Anti-Calmodulin Antibody

  • Atypical behavior of NFATc1 in cultured intercostal myofibers. 24383888

    The NFATc transcription factor family is responsible for coupling cytoplasmic calcium signals to transcription programs in a wide variety of cell types. In skeletal muscle, these transcription factors control the fiber type in response to muscle activity. This excitation-transcription (E-T) coupling permits functional adaptation of muscle according to use. The activity dependence of these transcription programs is sensitive to the firing patterns of the muscle, not merely the period of activity, enabling a nuanced adaptation to various functional tasks.Isolated skeletal muscle fibers expressing exogenous fluorescent NFATc1 were studied by confocal microscopy under stimulation both with and without pharmacological inhibitors. Western blots of whole muscle lysates were also used.This study investigates the activity dependent response of NFATc1 skeletal muscle fibers cultured from mice, comparing fibers of respiratory origin to muscles responsible for limb locomotion. Using patterns of stimulation known to strongly activate NFATc1 in the commonly cultured flexor digitorum brevis and soleus muscles, we have observed significant deactivation of NFATc1 in cultured intercostal muscle fibers. This effect is at least partially dependent on the action of JNK and CaMKII in intercostal fibers.Our findings highlight the role of lineage in the NFAT pathway, showing that the respiratory intercostal muscle fibers decode similar E-T coupling signals into NFAT transcriptional programs in a different manner from the more commonly studied locomotor muscles of the limbs.
    Tipo de documento:
    Referencia
    Referencia del producto:
    07-1491
    Nombre del producto:
    Anti-Calcineurin pan A Antibody

  • Metabotropic glutamate receptor 6 signaling enhances TRPM1 calcium channel function and increases melanin content in human melanocytes. 23452348

    Mutations in TRPM1, a calcium channel expressed in retinal bipolar cells and epidermal melanocytes, cause complete congenital stationary night blindness with no discernible skin phenotype. In the retina, TRPM1 activity is negatively coupled to metabotropic glutamate receptor 6 (mGluR6) signaling through Gαo and TRPM1 mutations result in the loss of responsiveness of TRPM1 to mGluR6 signaling. Here, we show that human melanocytes express mGluR6, and treatment of melanocytes with L-AP4, a type III mGluR-selective agonist, enhances Ca(2+) uptake. Knockdown of TRPM1 or mGluR6 by shRNA abolished L-AP4-induced Ca(2+) influx and TRPM1 currents, showing that TRPM1 activity in melanocytes is positively coupled to mGluR6 signaling. Gαo protein is absent in melanocytes. However, forced expression of Gαo restored negative coupling of TRPM1 to mGluR6 signaling, but treatment with pertussis toxin, an inhibitor of Gi /Go proteins, did not affect basal or mGluR6-induced Ca(2+) uptake. Additionally, chronic stimulation of mGluR6 altered melanocyte morphology and increased melanin content. These data suggest differences in coupling of TRPM1 function to mGluR6 signaling explain different cellular responses to glutamate in the retina and the skin.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB3073
    Nombre del producto:
    Anti-G Protein Goα Antibody, clone 2A

  • Cell-specific expression of plasma membrane calcium ATPase isoforms in retinal neurons. 12209837

    Ca(2+) extrusion by high-affinity plasma membrane calcium ATPases (PMCAs) is a principal mechanism for the clearance of Ca(2+) from the cytosol. The PMCA family consists of four isoforms (PMCA1-4). Little is known about the selective expression of these isoforms in brain tissues or about the physiological function conferred upon neurons by any given isoform. We investigated the cellular and subcellular distribution of PMCA isoforms in a mammalian retina. Mouse photoreceptors, cone bipolar cells and horizontal cells, which respond to light with a graded polarization, express isoform 1 (PMCA1) of the PMCA family. PMCA2 is localized to rod bipolar cells, horizontal cells, amacrine cells, and ganglion cells, and PMCA3 is predominantly expressed in spiking neurons, including both amacrine and ganglion cells but is also found in horizontal cells. PMCA4 was found to be selectively expressed in both synaptic layers. Optical measurements of Ca(2+) clearance showed that PMCAs mediate Ca(2+) extrusion in both rod and cone bipolar cells. In addition, we found that rod bipolar cells, but not cone bipolar cells possess a prominent Na(+)/Ca(2+) exchange mechanism. We conclude that PMCA isoforms are selectively expressed in retinal neurons and that processes of Ca(2+) clearance are different in rod and cone bipolar cells.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB305
    Nombre del producto:
    Anti-Choline Acetyltransferase Antibody, clone 1E6

  • Hypotensive hemorrhage increases calcium uptake capacity and Bcl-XL content of liver mitochondria. 17224795

    We tested the hypothesis that the response of mitochondrial uptake of calcium and content of Bcl proteins to reversible hemorrhagic shock increases the vulnerability for hepatocellular death. Pentobarbital-anesthetized rats were bled to a mean arterial pressure of 30 to 40 mmHg for 1 h. A subset was then resuscitated (isotonic sodium chloride solution, three times shed volume). Liver mitochondria were isolated at the end of hemorrhage and 1.5 h after the onset of resuscitation. Resuscitation accelerated mitochondrial respiration in the presence of adenosine diphosphate (state 3) above control (P<0.01). The respiratory control ratio ([RCR] state 3/state 4) was calculated using the respiratory rate in the presence of carboxyatractyloside (state 4). The RCR was depressed at the end of hemorrhage and recovered completely in response to resuscitation (P<0.05). The mitochondrial capacity for calcium uptake increased at the end of hemorrhage and remained greater than control (P<0.01) after resuscitation when plasma ornithine carbamoyltransferase (an index of hepatocellular injury) was greater than control (P<0.05). At this time, the capacity for calcium uptake was correlated with plasma ornithine carbamoyltransferase (r=0.819, P<0.01). Mitochondrial content of Bcl-xL, an antiapoptotic protein, was increased at the end of hemorrhage (P<0.03) with no further change after resuscitation and no change in mitochondrial Bak, a proapoptotic protein. Thus, mitochondrial mechanisms are triggered early during reversible hypovolemia that may limit the intensity of intracellular calcium signaling and its potential to cause cellular injury and death.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-536
    Nombre del producto:
    Anti-Bak Antibody, NT

  • A syntaxin 1, Galpha(o), and N-type calcium channel complex at a presynaptic nerve terminal: analysis by quantitative immunocolocalization. 15102922

    Presynaptic Ca(V)2.2 (N-type) calcium channels are subject to modulation by interaction with syntaxin 1 and by a syntaxin 1-sensitive Galpha(O) G-protein pathway. We used biochemical analysis of neuronal tissue lysates and a new quantitative test of colocalization by intensity correlation analysis at the giant calyx-type presynaptic terminal of the chick ciliary ganglion to explore the association of Ca(V)2.2 with syntaxin 1 and Galpha(O). Ca(V)2.2 could be localized by immunocytochemistry (antibody Ab571) in puncta on the release site aspect of the presynaptic terminal and close to synaptic vesicle clouds. Syntaxin 1 coimmunoprecipitated with Ca(V)2.2 from chick brain and chick ciliary ganglia and was widely distributed on the presynaptic terminal membrane. A fraction of the total syntaxin 1 colocalized with the Ca(V)2.2 puncta, whereas the bulk colocalized with MUNC18-1. Galpha(O,) whether in its trimeric or monomeric state, did not coimmunoprecipitate with Ca(V)2.2, MUNC18-1, or syntaxin 1. However, the G-protein exhibited a punctate staining on the calyx membrane with an intensity that varied in synchrony with that for both Ca channels and syntaxin 1 but only weakly with MUNC18-1. Thus, syntaxin 1 appears to be a component of two separate complexes at the presynaptic terminal, a minor one at the transmitter release site with Ca(V)2.2 and Galpha(O), as well as in large clusters remote from the release site with MUNC18-1. These syntaxin 1 protein complexes may play distinct roles in presynaptic biology.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB1991
    Nombre del producto:
    Anti-Neurofilament H (200 kDa) Antibody, lysine-serine-proline repeat

  • Heterogeneous expression of the voltage-gated calcium channel alpha2 subunit and the voltage-gated sodium channel alpha subunit in chicken spinal motoneurons. 19574720

    The localization of the voltage-gated calcium channel (VGCC) alpha2 and the voltage-gated sodium channel (VGSC) alpha subunits was immunohistochemically investigated in chicken spinal motoneurons. Approximately 83% and 46% of spinal motoneurons were positive for VGCCalpha2 and VGSCalpha subunits, respectively. Almost all VGSCalpha subunit-positive motoneurons exhibited the VGCCalpha2 subunit immunoreactivity. There were different patterns in occurrence, intensity or nuclear/cytoplasmic stainability of the VGCCalpha2 and VGSCalpha subunits among the motoneurons. This study presents the first cellular morphological evidence for the VGCCalpha2 and VGSCalpha subunits in spinal motoneurons, postulating that the heterogeneous expression of VGCCalpha2 and VGSCalpha subunits in the motoneurons may reflect various motor activities.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB143
    Nombre del producto:
    Anti-Choline Acetyltransferase (ChAT) Antibody

  • Calcium channels are involved in calcium oxalate crystal formation in specialized cells of Pistia stratiotes L. 15087302

    Pistia stratiotes produces large amounts of calcium (Ca) oxalate crystals in specialized cells called crystal idioblasts. The potential involvement of Ca(2+) channels in Ca oxalate crystal formation by crystal idioblasts was investigated.Anatomical, ultrastructural and physiological analyses were used on plants, fresh or fixed tissues, or protoplasts. Ca(2+) uptake by protoplasts was measured with (45)Ca(2+), and the effect of Ca(2+) channel blockers studied in intact plants. Labelled Ca(2+) channel blockers and a channel protein antibody were used to determine if Ca(2+) channels were associated with crystal idioblasts.(45)Ca(2+) uptake was more than two orders of magnitude greater for crystal idioblast protoplasts than mesophyll protoplasts, and idioblast number increased when medium Ca was increased. Plants grown on media containing 1-50 microM of the Ca(2+) channel blockers, isradipine, nifedipine or fluspirilene, showed almost complete inhibition of crystal formation. When fresh tissue sections were treated with the fluorescent dihydropyridine-type Ca(2+) channel blocker, DM-Bodipy-DHP, crystal idioblasts were intensely labelled compared with surrounding mesophyll, and the label appeared to be associated with the plasma membrane and the endoplasmic reticulum, which is shown to be abundant in idioblasts. An antibody to a mammalian Ca(2+) channel alpha1 subunit recognized a single band in a microsomal protein fraction but not soluble protein fraction on western blots, and it selectively and heavily labelled developing crystal idioblasts in tissue sections.The results demonstrate that Ca oxalate crystal idioblasts are enriched, relative to mesophyll cells, in dihydropyridine-type Ca(2+) channels and that the activity of these channels is important to transport and accumulation of Ca(2+) required for crystal formation.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB427
    Nombre del producto:
    Anti-Dihydropyridine-sensitive Calcium Channel α 1 Subunit Antibody, clone 1a

  • The role of ryanodine receptor type 3 in a mouse model of Alzheimer disease. 24476841

    Dysregulated endoplasmic reticulum (ER) calcium (Ca(2+)) signaling is reported to play an important role in Alzheimer disease (AD) pathogenesis. The role of ER Ca(2+) release channels, the ryanodine receptors (RyanRs), has been extensivelys tudied in AD models and RyanR expression and activity are upregulated in the brains of various familial AD (FAD) models.The objective of this study was to utilize a genetic approach to evaluate the importance of RyanR type 3 (RyanR3) in the context of AD pathology.The expression of RyanR3 was also elevated in hippocampus of APPPS1 mice (Thy1-APPKM670/671NL, Thy1-PS1L166P).In young (≤ 3 mo) APPPS1 mice, the deletion of RyanR3 increased hippocampal neuronal network excitability and accelerated AD pathology, leading to mushroom spine loss and increased amyloid accumulation. In contrast, deletion of RyanR3 in older APPPS1 mice (≥ 6 mo) rescued network excitability and mushroom spine loss, reduced amyloid plaque load and reduced spontaneous seizure occurrence.Our data suggests a dual role for RyanR3 in AD pathology. In young AD neurons, RyanR3 protects AD neurons from synaptic and network dysfunction. In older AD neurons, increased RyanR3 activity contributes to pathology. These results imply that blockade of RyanR3 may be beneficial for those in the later stages of the disease, but RyanR activators may be beneficial when used prior to disease onset or in its initial stages. Caffeine is an activator of RyanRs and our results may help to explain a complex epidemiological connection between coffee consumption in mid-life and risk of AD development in old age.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo