Molecular Nature of Anomalous L-Type Calcium Channels in Mouse Cerebellar Granule Cells

Koschak, Alexandra; Obermair, Gerald J.; Pivotto, Francesca; Sinnegger-Brauns, Martina J.; Striessnig, Jörg; Pietrobon, Daniela

doi:10.1523/jneurosci.4028-06.2007

Cited by 27 publications

(29 citation statements)

References 49 publications

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“…Qualitative PCRs were conducted using cDNA in the following range: retina 25 – 116 ngµl −1 , brain and muscle: 35 ngµl −1 and transfected cells 1.5 – 1.9 µgµl −1 . Specific primer for Cav1.1, 1.2, 1.4 as well as various splice forms of Cav1.3 were tested 20 , 21 , 22 , 23 , 24 25 .…”

Section: Methodsmentioning

confidence: 99%

Cav1.4 IT mouse as model for vision impairment in human congenital stationary night blindness type 2

et al. 2013

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Mutations in the CACNA1F gene encoding the Cav1.4 Ca2+ channel are associated with X-linked congenital stationary night blindness type 2 (CSNB2). Despite the increasing knowledge about the functional behavior of mutated channels in heterologous systems, the pathophysiological mechanisms that result in vision impairment remain to be elucidated. This work provides a thorough functional characterization of the novel IT mouse line that harbors the gain-of-function mutation I745T reported in a New Zealand CSNB2 family.1 Electroretinographic recordings in IT mice permitted a direct comparison with human data. Our data supported the hypothesis that a hyperpolarizing shift in the voltage-dependence of channel activation—as seen in the IT gain-of-function mutant2—may reduce the dynamic range of photoreceptor activity. Morphologically, the retinal outer nuclear layer in adult IT mutants was reduced in size and cone outer segments appeared shorter. The organization of the outer plexiform layer was disrupted, and synaptic structures of photoreceptors had a variable, partly immature, appearance. The associated visual deficiency was substantiated in behavioral paradigms. The IT mouse line serves as a specific model for the functional phenotype of human CSNB2 patients with gain-of-function mutations and may help to further understand the dysfunction in CSNB.

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Section: Methodsmentioning

confidence: 99%

Cav1.4 IT mouse as model for vision impairment in human congenital stationary night blindness type 2

et al. 2013

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“…The relative abundance of different LTCC transcripts was assessed by TaqMan quantitative PCR using a standard curve method as described previously (Koschak et al, 2007). Specific TaqMan Gene Expression Assays, designed to span exon-exon boundaries, were purchased from Applied Biosystems (Foster City, CA).…”

Section: Methodsmentioning

confidence: 99%

Expression and 1,4-Dihydropyridine-Binding Properties of Brain L-Type Calcium Channel Isoforms

Sinnegger-Brauns

Huber²,

Koschak³

et al. 2008

Mol Pharmacol

189

159

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“…Quantitative TaqMan RT-PCR-The relative abundance of different ␤ transcripts was assessed by quantitative RT-PCR using a standard curve method as described elsewhere (40,41). 4 The following specific TaqMan gene expression assays, designed to span exon-exon boundaries, were purchased from Applied Biosystems (Foster City, CA): ␤ 1 , Mm00518940_m1; ␤ 2 , Mm00659092_m1; ␤ 3 , Mm00432233_m1; and ␤ 4 , Mm00521623_m1.…”

Section: Rna Isolation and Reverse Transcription-2-week-oldmentioning

confidence: 99%

“…Employing quantitative TaqMan RT-PCR analysis, we determined whether and how much mRNA of the four ␤ subunits is expressed in hippocampus tissue of 2-week-old BALB/c mice and in cultured hippocampal neurons (40,41). 4 In hippocampus, we detected similar expression levels of all ␤ subunit isoforms.…”

Section: Cultured Hippocampal Neurons Express Mrna and Protein Of Allmentioning

confidence: 99%

Reciprocal Interactions Regulate Targeting of Calcium Channel β Subunits and Membrane Expression of α1 Subunits in Cultured Hippocampal Neurons

Obermair

Schlick

Biase

et al. 2010

Journal of Biological Chemistry

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Auxiliary ␤ subunits modulate current properties and mediate the functional membrane expression of voltage-gated Ca 2؉ channels in heterologous cells. In brain, all four ␤ isoforms are widely expressed, yet little is known about their specific roles in neuronal functions. Here, we investigated the expression and targeting properties of ␤ subunits and their role in membrane expression of Ca V 1.2 ␣ 1 subunits in cultured hippocampal neurons. Quantitative reverse transcription-PCR showed equal expression, and immunofluorescence showed a similar distribution of all endogenous ␤ subunits throughout dendrites and axons. High resolution microscopy of hippocampal neurons transfected with six different V5 epitope-tagged ␤ subunits demonstrated that all ␤ subunits were able to accumulate in synaptic terminals and to colocalize with postsynaptic Ca V 1.2, thus indicating a great promiscuity in ␣ 1 -␤ interactions. In contrast, restricted axonal targeting of ␤ 1 and weak colocalization of ␤ 4b with Ca V 1.2 indicated isoform-specific differences in local channel complex formation. Membrane expression of external hemagglutinin epitope-tagged Ca V 1.2 was strongly enhanced by all ␤ subunits in an isoform-specific manner. Conversely, mutating the ␣-interaction domain of Ca V 1.2 (W440A) abolished membrane expression and targeting into dendritic spines. This demonstrates that in neurons the interaction of a ␤ subunit with the ␣-interaction domain is absolutely essential for membrane expression of ␣ 1 subunits, as well as for the subcellular localization of ␤ subunits, which by themselves possess little or no targeting properties.Voltage-gated Ca 2ϩ channels (Ca V ) 3 provide key pathways for Ca 2ϩ entry into neurons and translate membrane depolarization into neurotransmitter secretion and gene regulation.Ca V s are composed of a pore-forming ␣ 1 subunit and the auxiliary ␣ 2 ␦ and ␤ subunits (1). Whereas the ␣ 1 subunits are responsible for voltage sensing and ion conduction, the auxiliary subunits have been implicated in membrane targeting and modulation of channel properties (for review see Ref.2). Presynaptic Ca V s regulate neurotransmitter release (3), and postsynaptic Ca V s activate the transcriptional regulators cAMP-response element-binding protein (CREB) and nuclear factor of activated T-cells (NFAT) (4, 5) and thus modulate long term potentiation (6). These functions reflect both the diversity of Ca V isoforms expressed in brain (7-11) and their differential subcellular localization in neurons (12-15).Four distinct ␤ isoforms have been identified (16 -19), all of which are expressed in brain (20 -23). They contain an Src homology 3 domain and a guanylate kinase domain (24 -27). However, the guanylate kinase fold is modified so that it can bind with high affinity to the so-called ␣-interaction domain (AID) in the intracellular I-II linker of Ca V ␣ 1 subunits (28, 29). The Src homology 3 and the guanylate kinase-like domains are highly conserved among the four genes encoding ␤ subunits (Cacnb1-b4; Fig. 1C), whereas t...

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Molecular Nature of Anomalous L-Type Calcium Channels in Mouse Cerebellar Granule Cells

Cited by 27 publications

References 49 publications

Cav1.4 IT mouse as model for vision impairment in human congenital stationary night blindness type 2

Cav1.4 IT mouse as model for vision impairment in human congenital stationary night blindness type 2

Expression and 1,4-Dihydropyridine-Binding Properties of Brain L-Type Calcium Channel Isoforms

Reciprocal Interactions Regulate Targeting of Calcium Channel β Subunits and Membrane Expression of α1 Subunits in Cultured Hippocampal Neurons

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