Characterization of two pathological gating-charge substitutions in Cav1.4 L-type calcium channels.

Cav1.4 L-type calcium channels are predominantly expressed at the photoreceptor terminals and in bipolar cells, mediating neurotransmitter release. Mutations in its gene, , can cause congenital stationary night-blindness type 2 (CSNB2).

A novel calcium channel Cavβ splice variant with unique properties predominates in the retina.

Cavβ subunits are essential for surface expression of voltage-gated calcium channel complexes and crucially modulate biophysical properties like voltage-dependent inactivation. Here, we describe the discovery and characterization of a novel Cavβ variant with distinct features that predominates in the retina. We determined spliced exons in retinal transcripts of the Cacnb2 gene, coding for Cavβ, by RNA-Seq data analysis and quantitative PCR.

Charge-Converting Nanoemulsions as Promising Retinal Drug and Gene Delivery Systems.

Aim: This study aimed to develop phosphatase-responsive ζ potential converting nanocarriers utilizing polyphosphate-coated cell-penetrating peptide (CPP)-decorated nanoemulsions (NEs) as a novel gene delivery system to retinal cells.

Methods: Poly-l-lysine (PLL) was first conjugated with oleylamine (OA) only at its carboxylic end to form the amphiphilic PLL-oleylamine (PLOA) conjugate. Afterward, NEs were loaded with PLOA prior to being coated with tripolyphosphate (TPP) to generate PLOA/TPP NEs.

Knockout of Ca1.3 L-type calcium channels in a mouse model of retinitis pigmentosa.

Retinitis Pigmentosa is a genetically heterogeneous, degenerative retinal disorder characterized by gradual dysfunction and death of photoreceptors, first rods and later cones, and progressive blindness. Studies suggested that application of L-type calcium channel blockers rescues photoreceptors in paradigms related to Ca overflow. To investigate whether Cav1.

Cav1.4 dysfunction and congenital stationary night blindness type 2.

Cav1.4 L-type Ca channels are predominantly expressed in retinal neurons, particularly at the photoreceptor terminals where they mediate sustained Ca entry needed for continuous neurotransmitter release at their ribbon synapses. Cav1.

Function of cone and cone-related pathways in Ca1.4 IT mice.

Ca1.4 L-type calcium channels are predominantly expressed in photoreceptor terminals playing a crucial role for synaptic transmission and, consequently, for vision. Human mutations in the encoding gene are associated with congenital stationary night blindness type-2.

Assessment of the Retina of Plp-α-Syn Mice as a Model for Studying Synuclein-Dependent Diseases.

Purpose: Synucleinopathies such as multiple system atrophy (MSA) and Parkinson's disease are associated with a variety of visual symptoms. Functional and morphological retinal aberrations are therefore supposed to be valuable biomarkers for these neurodegenerative diseases. This study examined the retinal morphology and functionality resulting from human α-synuclein (α-Syn) overexpression in the transgenic Plp-α-Syn mouse model.

Voltage-Gated Calcium Channels: Key Players in Sensory Coding in the Retina and the Inner Ear.

Calcium influx through voltage-gated Ca (Ca) channels is the first step in synaptic transmission. This review concerns Ca channels at ribbon synapses in primary sense organs and their specialization for efficient coding of stimuli in the physical environment. Specifically, we describe molecular, biochemical, and biophysical properties of the Ca channels in sensory receptor cells of the retina, cochlea, and vestibular apparatus, and we consider how such properties might change over the course of development and contribute to synaptic plasticity.

Protein kinase N1 critically regulates cerebellar development and long-term function.

Increasing evidence suggests that synapse dysfunctions are a major determinant of several neurodevelopmental and neurodegenerative diseases. Here we identify protein kinase N1 (PKN1) as a novel key player in fine-tuning the balance between axonal outgrowth and presynaptic differentiation in the parallel fiber-forming (PF-forming) cerebellar granule cells (Cgcs). Postnatal Pkn1-/- animals showed a defective PF-Purkinje cell (PF-PC) synapse formation.

Relevance of tissue specific subunit expression in channelopathies.

Channelopathies are a diverse group of human disorders that are caused by mutations in genes coding for ion channels or channel-regulating proteins. Several dozen channelopathies have been identified that involve both non-excitable cells as well as electrically active tissues like brain, skeletal and smooth muscle or the heart. In this review, we start out from the general question which ion channel genes are expressed tissue-selectively.

Cell-type-specific tuning of Cav1.3 Ca(2+)-channels by a C-terminal automodulatory domain.

Cav1.3 L-type Ca(2+)-channel function is regulated by a C-terminal automodulatory domain (CTM). It affects channel binding of calmodulin and thereby tunes channel activity by interfering with Ca(2+)- and voltage-dependent gating.

The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential.

Voltage-gated calcium channels are required for many key functions in the body. In this review, the different subtypes of voltage-gated calcium channels are described and their physiologic roles and pharmacology are outlined. We describe the current uses of drugs interacting with the different calcium channel subtypes and subunits, as well as specific areas in which there is strong potential for future drug development.

Gain-of-function nature of Cav1.4 L-type calcium channels alters firing properties of mouse retinal ganglion cells.

Proper function of Cav1.4 L-type calcium channels is crucial for neurotransmitter release in the retina. Our understanding about how different levels of Cav1.

A New Splicing Isoform of Cacna2d4 Mimicking the Effects of c.2451insC Mutation in the Retina: Novel Molecular and Electrophysiological Insights.

Purpose: Mutations in CACNA2D4 exon 25 cause photoreceptor dysfunction in humans (c.2406C→A mutation) and mice (c.2451insC mutation).

Spectrum of Cav1.4 dysfunction in congenital stationary night blindness type 2.

Defective retinal synaptic transmission in patients affected with congenital stationary night blindness type 2 (CSNB2) can result from different dysfunction phenotypes in Cav1.4 L-type calcium channels. Here we investigated two prototypical Cav1.

Differential neuronal targeting of a new and two known calcium channel β4 subunit splice variants correlates with their regulation of gene expression.

The β subunits of voltage-gated calcium channels regulate surface expression and gating of CaV1 and CaV2 α1 subunits and thus contribute to neuronal excitability, neurotransmitter release, and calcium-induced gene regulation. In addition, certain β subunits are targeted into the nucleus, where they interact directly with the epigenetic machinery. Whereas their involvement in this multitude of functions is reflected by a great molecular heterogeneity of β isoforms derived from four genes and abundant alternative splicing, little is known about the roles of individual β variants in specific neuronal functions.

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

Mutations in the CACNA1F gene encoding the Cav1.4 Ca (2+) 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.

What can naturally occurring mutations tell us about Ca(v)1.x channel function?

Voltage-gated Ca²⁺ channels allow for Ca²⁺-dependent intracellular signaling by directly mediating Ca²⁺ ion influx, by physical coupling to intracellular Ca²⁺ release channels or functional coupling to other ion channels such as Ca²⁺ activated potassium channels. L-type Ca²⁺ channels that comprise the family of Ca(v)1 channels are expressed in many electrically excitable tissues and are characterized by their unique sensitivity to dihydropyridines. In this issue, we summarize genetic defects in L-type Ca²⁺ channels and analyze their role in human diseases (Ca²⁺ channelopathies); e.

Functional properties of a newly identified C-terminal splice variant of Cav1.3 L-type Ca2+ channels.

An intramolecular interaction between a distal (DCRD) and a proximal regulatory domain (PCRD) within the C terminus of long Ca(v)1.3 L-type Ca(2+) channels (Ca(v)1.3(L)) is a major determinant of their voltage- and Ca(2+)-dependent gating kinetics.

Impact of gating modulation in CaV1.3 L-type calcium channels.

CaV1.3 L-type channels control inner hair cell (IHC) sensory and sinoatrial node (SAN) function, and excitability in central neurons by means of their low-voltage activation and inactivation properties. In SAN cells CaV1.

Modulation of Cav1.3 Ca2+ channel gating by Rab3 interacting molecule.

Neurotransmitter release and spontaneous action potentials during cochlear inner hair cell (IHC) development depend on the activity of Ca(v)1.3 voltage-gated L-type Ca(2+) channels. Their voltage- and Ca(2+)-dependent inactivation kinetics are slower than in other tissues but the underlying molecular mechanisms are not yet understood.

Channelopathies in Cav1.1, Cav1.3, and Cav1.4 voltage-gated L-type Ca2+ channels.

Voltage-gated Ca2+ channels couple membrane depolarization to Ca2+-dependent intracellular signaling events. This is achieved by mediating Ca2+ ion influx or by direct conformational coupling to intracellular Ca2+ release channels. The family of Cav1 channels, also termed L-type Ca2+ channels (LTCCs), is uniquely sensitive to organic Ca2+ channel blockers and expressed in many electrically excitable tissues.

Use-dependent block of voltage-gated Cav2.1 Ca2+ channels by petasins and eudesmol isomers.

Migraine is a frequent and often disabling disease. Treatment is unsatisfactory in many patients. A disturbed dynamic balance between excitatory and inhibitory signal processing with enhanced cortical activity probably underlies common forms of migraine.

Expression and 1,4-dihydropyridine-binding properties of brain L-type calcium channel isoforms.

The L-type calcium channel (LTCC) isoforms Ca(v)1.2 and Ca(v)1.3 display similar 1,4-dihydropyridine (DHP) binding properties and are both expressed in mammalian brain.