Dihydropyridine Receptors and Type 1 Ryanodine Receptors Constitute the Molecular Machinery for Voltage-Induced Ca2+ Release in Nerve Terminals

In striated muscles, Ca2+ release from internal stores through ryanodine receptor (RyR) channels is triggered by functional coupling to voltage-activated Ca2+ channels known as dihydropyridine receptors (DHPRs) located in the plasma membrane. In skeletal muscle, this occurs by a direct conformational link between the tissue-specific DHPR (Cav1.1) and RyR1, whereas in the heart the signal is carried from the cardiac-type DHPR (Cav1.2) to RyR2 by calcium ions acting as an activator. Subtypes of both channels are expressed in the central nervous system, but their functions and mechanisms of coupling are still poorly understood. We show here that complexes immunoprecipitated from solubilized rat brain membranes with antibodies against DHPR of the Cav1.2 or Cav1.3 subtypes contain RyR. Only type-1 RyR is co-precipitated, although the major brain isoform is RyR2. This suggests that, in neurons, DHPRs could communicate with RyRs by way of a strong molecular interaction and, more generally, that the physical link between DHPR and RyR shown to exist in skeletal muscle can be extended to other tissues.

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HN1L/JPT2: A signaling protein that connects NAADP generation to Ca2+ microdomain formation

Science Signaling ◽

10.1126/scisignal.abd5647 ◽

2021 ◽

Vol 14 (675) ◽

pp. eabd5647 ◽

Cited By ~ 1

Author(s):

Hannes G. Roggenkamp ◽

Imrankhan Khansahib ◽

Lola C. Hernandez C. ◽

Yunpeng Zhang ◽

Dmitri Lodygin ◽

...

Keyword(s):

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Ryanodine Receptors ◽

Cell Receptor ◽

Major Mechanism ◽

Molecular Machinery ◽

Direct Binding

NAADP-evoked Ca2+ release through type 1 ryanodine receptors (RYR1) is a major mechanism underlying the earliest signals in T cell activation, which are the formation of Ca2+ microdomains. In our characterization of the molecular machinery underlying NAADP action, we identified an NAADP-binding protein, called hematological and neurological expressed 1–like protein (HN1L) [also known as Jupiter microtubule-associated homolog 2 (JPT2)]. Gene deletion of Hn1l/Jpt2 in human Jurkat and primary rat T cells resulted in decreased numbers of initial Ca2+ microdomains and delayed the onset and decreased the amplitude of global Ca2+ signaling. Photoaffinity labeling demonstrated direct binding of NAADP to recombinant HN1L/JPT2. T cell receptor/CD3–dependent coprecipitation of HN1L/JPT2 with RYRs and colocalization of these proteins suggest that HN1L/JPT2 connects NAADP formation with the activation of RYR channels within the first seconds of T cell activation. Thus, HN1L/JPT2 enables NAADP to activate Ca2+ release from the endoplasmic reticulum through RYR.

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Catabolism of intracerebroventricularly injected 5-hydroxytryptamine in mouse: effect of coinjection of tryptamine and several pretreatments

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y93-031 ◽

1993 ◽

Vol 71 (3-4) ◽

pp. 201-204 ◽

Cited By ~ 1

Author(s):

B. Duff Sloley ◽

Shuzo Orikasa ◽

Alan A. Boulton

Keyword(s):

Monoamine Oxidase ◽

Receptor Antagonist ◽

Mouse Brain ◽

Monoamine Oxidase Inhibitor ◽

Oxidase Inhibitor ◽

Nerve Terminals ◽

Intracerebroventricular Injection ◽

Hydroxyindoleacetic Acid

The catabolism of intracerebroventricularly injected 5-hydroxytryptamine in mouse brain was investigated. Pretreatment of animals with the 5-hydroxytryptamine type 1 receptor antagonist metergoline, the 5-hydroxytryptamine type 2 receptor antagonist ketanserin, the 5-hydroxytryptamine reuptake inhibitor fluoxetine, or the selective 5-hydroxytryptamine neurotoxin 5,7-dihydroxytryptamine failed to alter the rate of catabolism of intracerebroventricularly administered 5-hydroxytryptamine. The monoamine oxidase inhibitor tranylcypromine effectively blocked degradation of injected 5-hydroxytryptamine and accumulation of 5-hydroxyindoleacetic acid. Coinjection of tryptamine with 5-hydroxytryptamine reduced the rate of conversion of 5-hydroxytryptamine to 5-hydroxyindoleacetic acid. These results indicate that intracerebroventricularly administered 5-hydroxytryptamine is removed by a monoamine oxidase dependent system. This catabolism is not affected by inhibition of presynaptic uptake, 5-hydroxytryptamine receptor type 1 or type 2 blockade, or destruction of serotonergic nerve terminals. The coadministration of tryptamine may prolong the residence period of 5-hydroxytryptamine through competition for monoamine oxidase.Key words: 5-hydroxytryptamine, tryptamine, monoamine oxidase, intracerebroventricular injection, catabolism.

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Effects of calmodulin on Ca2+-induced Ca2+ release of type 1 and type 3 ryanodine receptors.

The Japanese Journal of Pharmacology ◽

10.1016/s0021-5198(19)36847-7 ◽

1996 ◽

Vol 71 ◽

pp. 152

Author(s):

Takaaki Ikemoto ◽

Hiroshi Takeshima ◽

Masamitsu Iino ◽

Makoto Endo

Keyword(s):

Ryanodine Receptors ◽

Type 3

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Modulation of type-1 Ins(1,4,5)P3 receptor channels by the FK506-binding protein, FKBP12

Biochemical Journal ◽

10.1042/bj3610401 ◽

2002 ◽

Vol 361 (2) ◽

pp. 401-407 ◽

Cited By ~ 21

Author(s):

Sheila L. DARGAN ◽

Edward J. A. LEA ◽

Alan P. DAWSON

Keyword(s):

Lipid Bilayers ◽

Calcium Release ◽

Single Channel ◽

Binding Protein ◽

Ryanodine Receptors ◽

Fk506 Binding Protein ◽

Single Channel Activity ◽

And Function ◽

First Time

FK506-binding protein (FKBP12) is highly expressed in neuronal tissue, where it is proposed to localize calcineurin to intracellular calcium-release channels, ryanodine receptors and Ins(1,4,5)P3 receptors (InsP3Rs). The effects of FKBP12 on ryanodine receptors have been well characterized but the nature and function of binding of FKBP12 to InsP3R is more controversial, with evidence for and against a tight interaction between these two proteins. To investigate this, we incorporated purified type-1 InsP3R from rat cerebellum into planar lipid bilayers to monitor the effects of exogenous recombinant FKBP12 on single-channel activity, using K+ as the current carrier. Here we report for the first time that FKBP12 causes a substantial change in single-channel properties of the type-1 InsP3R, specifically to increase the amount of time the channel spends in a fully open state. In the presence of ATP, FKBP12 can also induce co-ordinated gating with neighbouring receptors. The effects of FKBP12 were reversed by FK506. We also present data showing that rapamycin, at sub-optimal concentrations of Ins(2,4,5)P3, decreases the rate of calcium release from cerebellar microsomes. These results provide evidence for a direct functional interaction between FKBP12 and the type-1 InsP3R.

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A probable role of dihydropyridine receptors in repression of Ca2+ sparks demonstrated in cultured mammalian muscle

AJP Cell Physiology ◽

10.1152/ajpcell.00592.2004 ◽

2006 ◽

Vol 290 (2) ◽

pp. C539-C553 ◽

Cited By ~ 56

Author(s):

Jingsong Zhou ◽

Jianxun Yi ◽

Leandro Royer ◽

Bradley S. Launikonis ◽

Adom González ◽

...

Keyword(s):

Ryanodine Receptors ◽

Critical Role ◽

Primary Cultures ◽

Inhibitory Effect ◽

Wild Type ◽

Dihydropyridine Receptors ◽

Skeletal Muscle Contraction ◽

Probable Role ◽

Emission Ratios

To activate skeletal muscle contraction, action potentials must be sensed by dihydropyridine receptors (DHPRs) in the T tubule, which signal the Ca2+ release channels or ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR) to open. We demonstrate here an inhibitory effect of the T tubule on the production of sparks of Ca2+ release. Murine primary cultures were confocally imaged for Ca2+ detection and T tubule visualization. After 72 h of differentiation, T tubules extended from the periphery for less than one-third of the myotube radius. Spontaneous Ca2+ sparks were found away from the region of cells where tubules were found. Immunostaining showed RyR1 and RyR3 isoforms in all areas, implying inhibition of both isoforms by a T tubule component. To test for a role of DHPRs in this inhibition, we imaged myotubes from dysgenic mice ( mdg) that lack DHPRs. These exhibited T tubule development similar to that of normal myotubes, but produced few sparks, even in regions where tubules were absent. To increase spark frequency, a high-Ca2+ saline with 1 mM caffeine was used. Wild-type cells in this saline plus 50 μM nifedipine retained the topographic suppression pattern of sparks, but dysgenic cells in high-Ca2+ saline did not. Shifted excitation and emission ratios of indo-1 in the cytosol or mag-indo-1 in the SR were used to image [Ca2+] in these compartments. Under the conditions of interest, wild-type and mdg cells had similar levels of free [Ca2+] in cytosol and SR. These data suggest that DHPRs play a critical role in reducing the rate of spontaneous opening of Ca2+ release channels and/or their susceptibility to Ca2+-induced activation, thereby suppressing the production of Ca2+ sparks.

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Reconstitution of local Ca2+ signaling between cardiac L-type Ca2+ channels and ryanodine receptors: insights into regulation by FKBP12.6

AJP Cell Physiology ◽

10.1152/ajpcell.00250.2005 ◽

2005 ◽

Vol 289 (6) ◽

pp. C1476-C1484 ◽

Cited By ~ 10

Author(s):

Sanjeewa A. Goonasekera ◽

S. R. Wayne Chen ◽

Robert T. Dirksen

Keyword(s):

Voltage Dependence ◽

Molecular Model ◽

Ryanodine Receptors ◽

Dihydropyridine Receptors ◽

Wide Range ◽

Fluorescence Change ◽

Current Densities ◽

Ca2 Channels

Ca+-induced Ca2+ release (CICR) in the heart involves local Ca2+ signaling between sarcolemmal L-type Ca2+ channels (dihydropyridine receptors, DHPRs) and type 2 ryanodine receptors (RyR2s) in the sarcoplasmic reticulum (SR). We reconstituted cardiac-like CICR by expressing a cardiac dihydropyridine-insensitive (T1066Y/Q1070M) α1-subunit (α1CYM) and RyR2 in myotubes derived from RyR1-knockout (dyspedic) mice. Myotubes expressing α1CYM and RyR2 were vesiculated and exhibited spontaneous Ca2+ oscillations that resulted in chaotic and uncontrolled contractions. Coexpression of FKBP12.6 (but not FKBP12.0) with α1CYM and RyR2 eliminated vesiculations and reduced the percentage of myotubes exhibiting uncontrolled global Ca2+ oscillations (63% and 13% of cells exhibited oscillations in the absence and presence of FKBP12.6, respectively). α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited robust and rapid electrically evoked Ca2+ transients that required extracellular Ca2+. Depolarization-induced Ca2+ release in α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited a bell-shaped voltage dependence that was fourfold larger than that of myotubes expressing α1CYM alone (maximal fluorescence change was 2.10 ± 0.39 and 0.54 ± 0.07, respectively), despite similar Ca2+ current densities. In addition, the gain of CICR in α1CYM/RyR2/FKBP12.6-expressing myotubes exhibited a nonlinear voltage dependence, being considerably larger at threshold potentials. We used this molecular model of local α1C-RyR2 signaling to assess the ability of FKBP12.6 to inhibit spontaneous Ca2+ release via a phosphomimetic mutation in RyR2 (S2808D). Electrically evoked Ca2+ release and the incidence of spontaneous Ca2+ oscillations did not differ in wild-type RyR2- and S2808D-expressing myotubes over a wide range of FKBP12.6 expression. Thus a negative charge at S2808 does not alter in situ regulation of RyR2 by FKBP12.6.

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Targeting and Retention of Type 1 Ryanodine Receptors to the Endoplasmic Reticulum

Journal of Biological Chemistry ◽

10.1074/jbc.m702457200 ◽

2007 ◽

Vol 282 (32) ◽

pp. 23096-23103 ◽

Cited By ~ 14

Author(s):

Gargi Meur ◽

Andrew K. T. Parker ◽

Fanni V. Gergely ◽

Colin W. Taylor

Keyword(s):

Endoplasmic Reticulum ◽

Ryanodine Receptors

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Role of Ryanodine Receptors in the Assembly of Calcium Release Units in Skeletal Muscle

The Journal of Cell Biology ◽

10.1083/jcb.140.4.831 ◽

1998 ◽

Vol 140 (4) ◽

pp. 831-842 ◽

Cited By ~ 107

Author(s):

Feliciano Protasi ◽

Clara Franzini-Armstrong ◽

Paul D. Allen

Keyword(s):

Electron Microscopy ◽

Skeletal Muscle ◽

Calcium Release ◽

Ryanodine Receptors ◽

Freeze Fracture ◽

Muscle Cells ◽

Dihydropyridine Receptors ◽

Section Electron ◽

Freeze Fracture Electron Microscopy

Abstract. In muscle cells, excitation–contraction (e–c) coupling is mediated by “calcium release units,” junctions between the sarcoplasmic reticulum (SR) and exterior membranes. Two proteins, which face each other, are known to functionally interact in those structures: the ryanodine receptors (RyRs), or SR calcium release channels, and the dihydropyridine receptors (DHPRs), or L-type calcium channels of exterior membranes. In skeletal muscle, DHPRs form tetrads, groups of four receptors, and tetrads are organized in arrays that face arrays of feet (or RyRs). Triadin is a protein of the SR located at the SR–exterior membrane junctions, whose role is not known. We have structurally characterized calcium release units in a skeletal muscle cell line (1B5) lacking Ry1R. Using immunohistochemistry and freeze-fracture electron microscopy, we find that DHPR and triadin are clustered in foci in differentiating 1B5 cells. Thin section electron microscopy reveals numerous SR–exterior membrane junctions lacking foot structures (dyspedic). These results suggest that components other than Ry1Rs are responsible for targeting DHPRs and triadin to junctional regions. However, DHPRs in 1B5 cells are not grouped into tetrads as in normal skeletal muscle cells suggesting that anchoring to Ry1Rs is necessary for positioning DHPRs into ordered arrays of tetrads. This hypothesis is confirmed by finding a “restoration of tetrads” in junctional domains of surface membranes after transfection of 1B5 cells with cDNA encoding for Ry1R.

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