scholarly journals Ankyrin-B Is Required for Intracellular Sorting of Structurally Diverse Ca2+ Homeostasis Proteins

1999 ◽  
Vol 147 (5) ◽  
pp. 995-1008 ◽  
Author(s):  
Shmuel Tuvia ◽  
Mona Buhusi ◽  
Lydia Davis ◽  
Mary Reedy ◽  
Vann Bennett
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Ryanodine Receptor ◽  
Striated Muscle ◽  
Intracellular Localization ◽  
Ryanodine Receptors ◽  
Ip3 Receptors ◽  
B Mice ◽  
Intracellular Sorting ◽  
Ankyrin B

This report describes a congenital myopathy and major loss of thymic lymphocytes in ankyrin-B (−/−) mice as well as dramatic alterations in intracellular localization of key components of the Ca2+ homeostasis machinery in ankyrin-B (−/−) striated muscle and thymus. The sacoplasmic reticulum (SR) and SR/T-tubule junctions are apparently preserved in a normal distribution in ankyrin-B (−/−) skeletal muscle based on electron microscopy and the presence of a normal pattern of triadin and dihydropyridine receptor. Therefore, the abnormal localization of SR/ER Ca ATPase (SERCA) and ryanodine receptors represents a defect in intracellular sorting of these proteins in skeletal muscle. Extrapolation of these observations suggests defective targeting as the basis for abnormal localization of ryanodine receptors, IP3 receptors and SERCA in heart, and of IP3 receptors in the thymus of ankyrin-B (−/−) mice. Mis-sorting of SERCA 2 and ryanodine receptor 2 in ankyrin-B (−/−) cardiomyocytes is rescued by expression of 220-kD ankyrin-B, demonstrating that lack of the 220-kD ankyrin-B polypeptide is the primary defect in these cells. Ankyrin-B is associated with intracellular vesicles, but is not colocalized with the bulk of SERCA 1 or ryanodine receptor type 1 in skeletal muscle. These data provide the first evidence of a physiological requirement for ankyrin-B in intracellular targeting of the calcium homeostasis machinery of striated muscle and immune system, and moreover, support a catalytic role that does not involve permanent stoichiometric complexes between ankyrin-B and targeted proteins. Ankyrin-B is a member of a family of adapter proteins implicated in restriction of diverse proteins to specialized plasma membrane domains. Similar mechanisms involving ankyrins may be essential for segregation of functionally defined proteins within specialized regions of the plasma membrane and within the Ca2+ homeostasis compartment of the ER.

scholarly journals No evidence for inositol 1,4,5-trisphosphate–dependent Ca2+ release in isolated fibers of adult mouse skeletal muscle

2012 ◽  
Vol 140 (2) ◽  
pp. 235-241 ◽  
Author(s):  
Bert Blaauw ◽  
Paola del Piccolo ◽  
Laura Rodriguez ◽  
Victor-Hugo Hernandez Gonzalez ◽  
Lisa Agatea ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Adult Mouse ◽  
Striated Muscle ◽  
Direct Injection ◽  
Ryanodine Receptors ◽  
Calcium Signal ◽  
Ip3 Receptors ◽  
Adult Skeletal Muscle ◽  
Mouse Skeletal Muscle ◽  
Inositol 1,4,5 Trisphosphate

The presence and role of functional inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) in adult skeletal muscle are controversial. The current consensus is that, in adult striated muscle, the relative amount of IP3Rs is too low and the kinetics of Ca2+ release from IP3R is too slow compared with ryanodine receptors to contribute to the Ca2+ transient during excitation–contraction coupling. However, it has been suggested that IP3-dependent Ca2+ release may be involved in signaling cascades leading to regulation of muscle gene expression. We have reinvestigated IP3-dependent Ca2+ release in isolated flexor digitorum brevis (FDB) muscle fibers from adult mice. Although Ca2+ transients were readily induced in cultured C2C12 muscle cells by (a) UTP stimulation, (b) direct injection of IP3, or (c) photolysis of membrane-permeant caged IP3, no statistically significant change in calcium signal was detected in adult FDB fibers. We conclude that the IP3–IP3R system does not appear to affect global calcium levels in adult mouse skeletal muscle.

scholarly journals Triadin Binding to the C-Terminal Luminal Loop of the Ryanodine Receptor is Important for Skeletal Muscle Excitation–Contraction Coupling

2007 ◽  
Vol 130 (4) ◽  
pp. 365-378 ◽  
Author(s):  
Sanjeewa A. Goonasekera ◽  
Nicole A. Beard ◽  
Linda Groom ◽  
Takashi Kimura ◽  
Alla D. Lyfenko ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Striated Muscle ◽  
Single Channel ◽  
Triple Mutant ◽  
Double Mutation ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Functional Studies

Ca2+ release from intracellular stores is controlled by complex interactions between multiple proteins. Triadin is a transmembrane glycoprotein of the junctional sarcoplasmic reticulum of striated muscle that interacts with both calsequestrin and the type 1 ryanodine receptor (RyR1) to communicate changes in luminal Ca2+ to the release machinery. However, the potential impact of the triadin association with RyR1 in skeletal muscle excitation–contraction coupling remains elusive. Here we show that triadin binding to RyR1 is critically important for rapid Ca2+ release during excitation–contraction coupling. To assess the functional impact of the triadin-RyR1 interaction, we expressed RyR1 mutants in which one or more of three negatively charged residues (D4878, D4907, and E4908) in the terminal RyR1 intraluminal loop were mutated to alanines in RyR1-null (dyspedic) myotubes. Coimmunoprecipitation revealed that triadin, but not junctin, binding to RyR1 was abolished in the triple (D4878A/D4907A/E4908A) mutant and one of the double (D4907A/E4908A) mutants, partially reduced in the D4878A/D4907A double mutant, but not affected by either individual (D4878A, D4907A, E4908A) mutations or the D4878A/E4908A double mutation. Functional studies revealed that the rate of voltage- and ligand-gated SR Ca2+ release were reduced in proportion to the degree of interruption in triadin binding. Ryanodine binding, single channel recording, and calcium release experiments conducted on WT and triple mutant channels in the absence of triadin demonstrated that the luminal loop mutations do not directly alter RyR1 function. These findings demonstrate that junctin and triadin bind to different sites on RyR1 and that triadin plays an important role in ensuring rapid Ca2+ release during excitation–contraction coupling in skeletal muscle.

scholarly journals The subcellular distribution of dystrophin in mouse skeletal, cardiac, and smooth muscle.

1991 ◽  
Vol 115 (2) ◽  
pp. 411-421 ◽  
Author(s):  
T J Byers ◽  
L M Kunkel ◽  
S C Watkins
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Plasma Membrane ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Adherens Junctions ◽  
Myotendinous Junction ◽  
Elevated Concentration ◽  
Western Blots ◽  
Functional Roles

We use a highly specific and sensitive antibody to further characterize the distribution of dystrophin in skeletal, cardiac, and smooth muscle. No evidence for localization other than at the cell surface is apparent in skeletal muscle and no 427-kD dystrophin labeling was detected in sciatic nerve. An elevated concentration of dystrophin appears at the myotendinous junction and the neuromuscular junction, labeling in the latter being more intense specifically in the troughs of the synaptic folds. In cardiac muscle the distribution of dystrophin is limited to the surface plasma membrane but is notably absent from the membrane that overlays adherens junctions of the intercalated disks. In smooth muscle, the plasma membrane labeling is considerably less abundant than in cardiac or skeletal muscle and is found in areas of membrane underlain by membranous vesicles. As in cardiac muscle, smooth muscle dystrophin seems to be excluded from membrane above densities that mark adherens junctions. Dystrophin appears as a doublet on Western blots of skeletal and cardiac muscle, and as a single band of lower abundance in smooth muscle that corresponds most closely in molecular weight to the upper band of the striated muscle doublet. The lower band of the doublet in striated muscle appears to lack a portion of the carboxyl terminus and may represent a dystrophin isoform. Isoform differences and the presence of dystrophin on different specialized membrane surfaces imply multiple functional roles for the dystrophin protein.

scholarly journals Tracking the sarcoplasmic reticulum membrane voltage in muscle with a FRET biosensor

2018 ◽  
Vol 150 (8) ◽  
pp. 1163-1177 ◽  
Author(s):  
Colline Sanchez ◽  
Christine Berthier ◽  
Bruno Allard ◽  
Jimmy Perrot ◽  
Clément Bouvard ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Sarcoplasmic Reticulum ◽  
Voltage Clamp ◽  
Ryanodine Receptor ◽  
Striated Muscle ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Membrane Voltage ◽  
Voltage Sensitivity ◽  
Cell Functions

Ion channel activity in the plasma membrane of living cells generates voltage changes that are critical for numerous biological functions. The membrane of the endoplasmic/sarcoplasmic reticulum (ER/SR) is also endowed with ion channels, but whether changes in its voltage occur during cellular activity has remained ambiguous. This issue is critical for cell functions that depend on a Ca2+ flux across the reticulum membrane. This is the case for contraction of striated muscle, which is triggered by opening of ryanodine receptor Ca2+ release channels in the SR membrane in response to depolarization of the transverse invaginations of the plasma membrane (the t-tubules). Here, we use targeted expression of voltage-sensitive fluorescence resonance energy transfer (FRET) probes of the Mermaid family in differentiated muscle fibers to determine whether changes in SR membrane voltage occur during depolarization–contraction coupling. In the absence of an SR targeting sequence, FRET signals from probes present in the t-tubule membrane allow calibration of the voltage sensitivity and amplitude of the response to voltage-clamp pulses. Successful SR targeting of the probes was achieved using an N-terminal domain of triadin, which completely eliminates voltage-clamp–activated FRET signals from the t-tubule membrane of transfected fibers. In fibers expressing SR-targeted Mermaid probes, activation of SR Ca2+ release in the presence of intracellular ethyleneglycol-bis(β-amino-ethyl ether)-N,N,N′,N′-tetra acetic acid (EGTA) results in an accompanying FRET signal. We find that this signal results from pH sensitivity of the probe, which detects cytosolic acidification because of the release of protons upon Ca2+ binding to EGTA. When EGTA is substituted with either 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid or the contraction blocker N-benzyl-p-toluene sulfonamide, we find no indication of a substantial change in the FRET response caused by a voltage change. These results suggest that the ryanodine receptor–mediated SR Ca2+ efflux is well balanced by concomitant counterion currents across the SR membrane.

scholarly journals Stac adaptor proteins regulate trafficking and function of muscle and neuronal L-type Ca2+ channels

2014 ◽  
Vol 112 (2) ◽  
pp. 602-606 ◽  
Author(s):  
Alexander Polster ◽  
Stefano Perni ◽  
Hicham Bichraoui ◽  
Kurt G. Beam
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Ryanodine Receptors ◽  
Adaptor Proteins ◽  
Surface Expression ◽  
Ec Coupling ◽  
And Function

Excitation–contraction (EC) coupling in skeletal muscle depends upon trafficking of CaV1.1, the principal subunit of the dihydropyridine receptor (DHPR) (L-type Ca2+ channel), to plasma membrane regions at which the DHPRs interact with type 1 ryanodine receptors (RyR1) in the sarcoplasmic reticulum. A distinctive feature of this trafficking is that CaV1.1 expresses poorly or not at all in mammalian cells that are not of muscle origin (e.g., tsA201 cells), in which all of the other nine CaV isoforms have been successfully expressed. Here, we tested whether plasma membrane trafficking of CaV1.1 in tsA201 cells is promoted by the adapter protein Stac3, because recent work has shown that genetic deletion of Stac3 in skeletal muscle causes the loss of EC coupling. Using fluorescently tagged constructs, we found that Stac3 and CaV1.1 traffic together to the tsA201 plasma membrane, whereas CaV1.1 is retained intracellularly when Stac3 is absent. Moreover, L-type Ca2+ channel function in tsA201 cells coexpressing Stac3 and CaV1.1 is quantitatively similar to that in myotubes, despite the absence of RyR1. Although Stac3 is not required for surface expression of CaV1.2, the principle subunit of the cardiac/brain L-type Ca2+ channel, Stac3 does bind to CaV1.2 and, as a result, greatly slows the rate of current inactivation, with Stac2 acting similarly. Overall, these results indicate that Stac3 is an essential chaperone of CaV1.1 in skeletal muscle and that in the brain, Stac2 and Stac3 may significantly modulate CaV1.2 function.

scholarly journals unc-68 encodes a ryanodine receptor involved in regulating C. elegans body-wall muscle contraction.

1996 ◽  
Vol 134 (4) ◽  
pp. 885-893 ◽  
Author(s):  
E B Maryon ◽  
R Coronado ◽  
P Anderson
Keyword(s):  
Muscle Contraction ◽  
Ryanodine Receptor ◽  
Body Wall ◽  
Striated Muscle ◽  
Ryanodine Receptors ◽  
Binding Activity ◽  
Body Wall Muscle ◽  
Calcium Signal ◽  
C Elegans ◽  
Muscle Ultrastructure

Striated muscle contraction is elicited by the release of stored calcium ions through ryanodine receptor channels in the sarcoplasmic reticulum. ryr-1 is a C. elegans ryanodine receptor homologue that is expressed in body-wall muscle cells used for locomotion. Using genetic methods, we show that ryr-1 is the previously identified locus unc-68. First, transposon-induced deletions within ryr-1 are alleles of unc-68. Second, transformation of unc-68 mutants with ryr-1 genomic DNA results in rescue of the Unc phenotype. unc-68 mutants move poorly, exhibiting an incomplete flaccid paralysis, yet have normal muscle ultrastructure. The mutants are insensitive to the paralytic effects of ryanodine, and lack detectable ryanodine-binding activity. The Unc-68 phenotype suggests that ryanodine receptors are not essential for excitation-contraction coupling in nematodes, but act to amplify a (calcium) signal that is sufficient for contraction.

scholarly journals Halothane modulation of skeletal muscle ryanodine receptors: dependence on Ca2+, Mg2+, and ATP

2008 ◽  
Vol 294 (4) ◽  
pp. C1103-C1112 ◽  
Author(s):  
Paula L. Diaz-Sylvester ◽  
Maura Porta ◽  
Julio A. Copello
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Lipid Bilayers ◽  
Ryanodine Receptor ◽  
Genetic Disorder ◽  
Ryanodine Receptors ◽  
Volatile Anesthetic ◽  
Planar Lipid Bilayers ◽  
Wild Type ◽  
Highly Sensitive

Malignant hyperthermia (MH) susceptibility is a genetic disorder of skeletal muscle associated with mutations in the ryanodine receptor isoform 1 (RyR1) of sarcoplasmic reticulum (SR). In MH-susceptible skeletal fibers, RyR1-mediated Ca2+ release is highly sensitive to activation by the volatile anesthetic halothane. Indeed, studies with isolated RyR1 channels (using simple Cs+ solutions) found that halothane selectively affects mutated but not wild-type RyR1 function. However, studies in skeletal fibers indicate that halothane can also activate wild-type RyR1-mediated Ca2+ release. We hypothesized that endogenous RyR1 agonists (ATP, lumenal Ca2+) may increase RyR1 sensitivity to halothane. Consequently, we studied how these agonists affect halothane action on rabbit skeletal RyR1 reconstituted into planar lipid bilayers. We found that cytosolic ATP is required for halothane-induced activation of the skeletal RyR1. Unlike RyR1, cardiac RyR2 (much less sensitive to ATP) responded to halothane even in the absence of this agonist. ATP-dependent halothane activation of RyR1 was enhanced by cytosolic Ca2+ (channel agonist) and counteracted by Mg2+ (channel inhibitor). Dantrolene, a muscle relaxant used to treat MH episodes, did not affect RyR1 or RyR2 basal activity and did not interfere with halothane-induced activation. Studies with skeletal SR microsomes confirmed that halothane-induced RyR1-mediated SR Ca2+ release is enhanced by high ATP-low Mg2+ in the cytosol and by increased SR Ca2+ load. Thus, physiological or pathological processes that induce changes in cellular levels of these modulators could affect RyR1 sensitivity to halothane in skeletal fibers, including the outcome of halothane-induced contracture tests used to diagnose MH susceptibility.

IP3 receptors, IP3 transients, and nucleus-associated Ca2+ signals in cultured skeletal muscle

2000 ◽  
Vol 278 (5) ◽  
pp. C998-C1010 ◽  
Author(s):  
Enrique Jaimovich ◽  
Roberto Reyes ◽  
Jose L. Liberona ◽  
Jeanne A. Powell
Keyword(s):  
Skeletal Muscle ◽  
Microsomal Fraction ◽  
Ryanodine Receptors ◽  
Nuclear Fraction ◽  
Ip3 Receptors ◽  
Cell Nuclei ◽  
Displacement Assay ◽  
Intracellular Signal ◽  
External K

Inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) and ryanodine receptors (RyR) were localized in cultured rodent muscle fractions by binding of radiolabeled ligands (IP3 and ryanodine), and IP3R were visualized in situ by fluorescence immunocytological techniques. Also explored was the effect of K+ depolarization on IP3 mass and Ca2+ transients studied using a radio-receptor displacement assay and fluorescence imaging of intracellular fluo 3. RyR were located in a microsomal fraction; IP3R were preferentially found in the nuclear fraction. Fluorescence associated with anti-IP3R antibody was found in the region of the nuclear envelope and in a striated pattern in the sarcoplasmic areas. An increase in external K+ affected membrane potential and produced an IP3 transient. Rat myotubes displayed a fast-propagating Ca2+ signal, corresponding to the excitation-contraction coupling transient and a much slower Ca2+ wave. Both signals were triggered by high external K+ and were independent of external Ca2+. Slow waves were associated with cell nuclei and were propagated leaving “glowing” nuclei behind. Different roles are proposed for at least two types of Ca2+ release channels, each mediating an intracellular signal in cultured skeletal muscle.

scholarly journals Fish Glucose Transporter (GLUT)-4 Differs from Rat GLUT4 in Its Traffic Characteristics but Can Translocate to the Cell Surface in Response to Insulin in Skeletal Muscle Cells

Endocrinology ◽  
2007 ◽  
Vol 148 (11) ◽  
pp. 5248-5257 ◽  
Author(s):  
Mònica Díaz ◽  
Costin N. Antonescu ◽  
Encarnación Capilla ◽  
Amira Klip ◽  
Josep V. Planas
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Glucose Uptake ◽  
Brown Trout ◽  
Glucose Transporter ◽  
Intracellular Localization ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Glut 4

In mammals, glucose transporter (GLUT)-4 plays an important role in glucose homeostasis mediating insulin action to increase glucose uptake in insulin-responsive tissues. In the basal state, GLUT4 is located in intracellular compartments and upon insulin stimulation is recruited to the plasma membrane, allowing glucose entry into the cell. Compared with mammals, fish are less efficient restoring plasma glucose after dietary or exogenous glucose administration. Recently our group cloned a GLUT4-homolog in skeletal muscle from brown trout (btGLUT4) that differs in protein motifs believed to be important for endocytosis and sorting of mammalian GLUT4. To study the traffic of btGLUT4, we generated a stable L6 muscle cell line overexpressing myc-tagged btGLUT4 (btGLUT4myc). Insulin stimulated btGLUT4myc recruitment to the cell surface, although to a lesser extent than rat-GLUT4myc, and enhanced glucose uptake. Interestingly, btGLUT4myc showed a higher steady-state level at the cell surface under basal conditions than rat-GLUT4myc due to a higher rate of recycling of btGLUT4myc and not to a slower endocytic rate, compared with rat-GLUT4myc. Furthermore, unlike rat-GLUT4myc, btGLUT4myc had a diffuse distribution throughout the cytoplasm of L6 myoblasts. In primary brown trout skeletal muscle cells, insulin also promoted the translocation of endogenous btGLUT4 to the plasma membrane and enhanced glucose transport. Moreover, btGLUT4 exhibited a diffuse intracellular localization in unstimulated trout myocytes. Our data suggest that btGLUT4 is subjected to a different intracellular traffic from rat-GLUT4 and may explain the relative glucose intolerance observed in fish.

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