scholarly journals A malignant hyperthermia–inducing mutation in RYR1 (R163C): alterations in Ca2+ entry, release, and retrograde signaling to the DHPR

2010 ◽  
Vol 135 (6) ◽  
pp. 619-628 ◽  
Author(s):  
Eric Estève ◽  
José M. Eltit ◽  
Roger A. Bannister ◽  
Kai Liu ◽  
Isaac N. Pessah ◽  
...  
Keyword(s):  
Malignant Hyperthermia ◽  
Conformational Changes ◽  
Rank Order ◽  
Decay Rates ◽  
Release Channel ◽  
Bidirectional Signaling ◽  
New Findings ◽  
Rate Of Decay ◽  
Retrograde Signal

Bidirectional signaling between the sarcolemmal L-type Ca2+ channel (1,4-dihydropyridine receptor [DHPR]) and the sarcoplasmic reticulum (SR) Ca2+ release channel (type 1 ryanodine receptor [RYR1]) of skeletal muscle is essential for excitation–contraction coupling (ECC) and is a well-understood prototype of conformational coupling. Mutations in either channel alter coupling fidelity and with an added pharmacologic stimulus or stress can trigger malignant hyperthermia (MH). In this study, we measured the response of wild-type (WT), heterozygous (Het), or homozygous (Hom) RYR1-R163C knock-in mouse myotubes to maintained K+ depolarization. The new findings are: (a) For all three genotypes, Ca2+ transients decay during prolonged depolarization, and this decay is not a consequence of SR depletion or RYR1 inactivation. (b) The R163C mutation retards the decay rate with a rank order WT > Het > Hom. (c) The removal of external Ca2+ or the addition of Ca2+ entry blockers (nifedipine, SKF96365, and Ni2+) enhanced the rate of decay in all genotypes. (d) When Ca2+ entry is blocked, the decay rates are slower for Hom and Het than WT, indicating that the rate of inactivation of ECC is affected by the R163C mutation and is genotype dependent (WT > Het > Hom). (e) Reduced ECC inactivation in Het and Hom myotubes was shown directly using two identical K+ depolarizations separated by varying time intervals. These data suggest that conformational changes induced by the R163C MH mutation alter the retrograde signal that is sent from RYR1 to the DHPR, delaying the inactivation of the DHPR voltage sensor.

scholarly journals Increased basal metabolic rate in mice susceptible to malignant hyperthermia and heat stroke

2021 ◽  
Vol 154 (9) ◽  
Author(s):  
Matteo Serano ◽  
Laura Pietrangelo ◽  
Cecilia Paolini ◽  
Flavia A. Guarnier ◽  
Feliciano Protasi
Keyword(s):  
Malignant Hyperthermia ◽  
Heat Stroke ◽  
Gene Encoding ◽  
Release Channel ◽  
Western Blots ◽  
Ec Coupling ◽  
Mitochondrial Volume ◽  
Total Body ◽  
Old Mice

Ryanodine receptor type-1 (RYR1) and Calsequestrin-1 (CASQ1) proteins, located in the sarcoplasmic reticulum (SR), are two of the main players in skeletal excitation–contraction (EC) coupling. Mutations in the human RYR1 gene (encoding for the SR Ca2+ release channel) and ablation in mice of CASQ1 (a SR Ca2+ binding protein) cause hypersensitivity to halogenated anesthetics (malignant hyperthermia [MH] susceptibility) and to heat (heat stroke; HS). As both MH and HS are characterized by excessive cytosolic Ca2+ levels and hypermetabolic responses, we studied the metabolism of 4-mo-old mice from two different lines that are MH/HS susceptible: knock-in mice carrying a human MH mutation (RYR1YS) and CASQ1-knockout (ko) mice. RYR1YS and, to a lesser degree, CASQ1-null mice show an increased volume of oxygen consumption (VO2) and a lower respiratory quotient (RQ) compared with WT mice (indicative of a metabolism that relies more on lipids). This finding is accompanied by a reduction in total body fat mass in both Y522S and CASQ1-null mice (again, compared with WT). In addition, we found that RYR1YS and CASQ1-null mice have an increased food consumption (+26.04% and +25.58% grams/day, respectively) and higher basal core temperature (+0.57°C and +0.54°C, respectively) compared with WT mice. Finally, Western blots and electron microscopy indicated that, in hyperthermic mice, (1) SERCA (used to remove myoplasmic Ca2+) and UCP3 (responsible for a thermogenic process that dissipates mitochondrial H+ gradient) are overexpressed, and (2) mitochondrial volume and percentage of damaged mitochondria are both increased. In conclusion, the MH/HS phenotype in RYR1YS and CASQ1-null mice is associated with an intrinsically increased basal metabolism.

scholarly journals A novel saline-soluble, rapidly-metabolized RyR1 inhibitor rescues volatile anesthesia-induced death and environmental heat stroke in a mouse model relevant to malignant hyperthermia

2020 ◽  
Author(s):  
Toshiko Yamazawa ◽  
Takuya Kobayashi ◽  
Nagomi Kurebayashi ◽  
Masato Konishi ◽  
Satoru Noguchi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Water Solubility ◽  
Heat Stroke ◽  
Release Channel ◽  
Volatile Anesthesia ◽  
Intracellular Ca ◽  
Rapid Clearance

AbstractMutations in the type 1 ryanodine receptor (RyR1), a Ca2+ release channel in skeletal muscle, hyperactivate the channel to cause malignant hyperthermia (MH) and are implicated in severe heat stroke. Dantrolene, the only approved drug for MH, has the disadvantages of having very poor water solubility and long plasma half-life. We show here that a novel RyR1-selective inhibitor, 6,7-(methylenedioxy)-1-octyl-4-quinolone-3-carboxylic acid (Compound 1), effectively rescues MH and heat stroke in several mouse models relevant to MH. Compound 1 reduced resting intracellular Ca2+, inhibited halothane-induced Ca2+ release, suppressed caffeine-induced contracture in skeletal muscle, reduced sarcolemmal cation influx, and prevented or reversed the fulminant MH crisis by isoflurane anesthesia and heat stroke by environmental heat stress. Notably, Compound 1 has great advantages of better water solubility and rapid clearance in vivo over dantrolene. Compound 1 has the potential to be a promising new candidate for effective treatment of patients carrying RyR1 mutations.

scholarly journals Junctional trafficking and restoration of retrograde signaling by the cytoplasmic RyR1 domain

2017 ◽  
Vol 150 (2) ◽  
pp. 293-306 ◽  
Author(s):  
Alexander Polster ◽  
Stefano Perni ◽  
Dilyana Filipova ◽  
Ong Moua ◽  
Joshua D. Ohrtman ◽  
...  
Keyword(s):  
Large Fraction ◽  
Freeze Fracture ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Cytoplasmic Domain ◽  
Retrograde Signaling ◽  
Bidirectional Signaling ◽  
Retrograde Signal ◽  
Fracture Electron

The type 1 ryanodine receptor (RyR1) in skeletal muscle is a homotetrameric protein that releases Ca2+ from the sarcoplasmic reticulum (SR) in response to an “orthograde” signal from the dihydropyridine receptor (DHPR) in the plasma membrane (PM). Additionally, a “retrograde” signal from RyR1 increases the amplitude of the Ca2+ current produced by CaV1.1, the principle subunit of the DHPR. This bidirectional signaling is thought to depend on physical links, of unknown identity, between the DHPR and RyR1. Here, we investigate whether the isolated cytoplasmic domain of RyR1 can interact structurally or functionally with CaV1.1 by producing an N-terminal construct (RyR11:4300) that lacks the C-terminal membrane domain. In CaV1.1-null (dysgenic) myotubes, RyR11:4300 is diffusely distributed, but in RyR1-null (dyspedic) myotubes it localizes in puncta at SR–PM junctions containing endogenous CaV1.1. Fluorescence recovery after photobleaching indicates that diffuse RyR11:4300 is mobile, whereas resistance to being washed out with a large-bore micropipette indicates that the punctate RyR11:4300 stably associates with PM–SR junctions. Strikingly, expression of RyR11:4300 in dyspedic myotubes causes an increased amplitude, and slowed activation, of Ca2+ current through CaV1.1, which is almost identical to the effects of full-length RyR1. Fast protein liquid chromatography indicates that ∼25% of RyR11:4300 in diluted cytosolic lysate of transfected tsA201 cells is present in complexes larger in size than the monomer, and intermolecular fluorescence resonance energy transfer implies that RyR11:4300 is significantly oligomerized within intact tsA201 cells and dyspedic myotubes. A large fraction of these oligomers may be homotetramers because freeze-fracture electron micrographs reveal that the frequency of particles arranged like DHPR tetrads is substantially increased by transfecting RyR-null myotubes with RyR11:4300. In summary, the RyR1 cytoplasmic domain, separated from its SR membrane anchor, retains a tendency toward oligomerization/tetramerization, binds to SR–PM junctions in myotubes only if CaV1.1 is also present and is fully functional in retrograde signaling to CaV1.1.

New insights into the structural basis of integrin activation

Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1155-1159 ◽  
Author(s):  
Jian-Ping Xiong ◽  
Thilo Stehle ◽  
Simon L. Goodman ◽  
M. Amin Arnaout
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Structural Basis ◽  
Integrin Activation ◽  
Cellular Functions ◽  
Electron Microscopic ◽  
The Past ◽  
Intracellular Signals ◽  
Bidirectional Signaling ◽  
New Hypothesis

Abstract Integrins are cell adhesion receptors that communicate biochemical and mechanical signals in a bidirectional manner across the plasma membrane and thus influence most cellular functions. Intracellular signals switch integrins into a ligand-competent state as a result of elicited conformational changes in the integrin ectodomain. Binding of extracellular ligands induces, in turn, structural changes that convey distinct signals to the cell interior. The structural basis of this bidirectional signaling has been the focus of intensive study for the past 3 decades. In this perspective, we develop a new hypothesis for integrin activation based on recent crystallographic, electron microscopic, and biochemical studies.

scholarly journals Human Immunodeficiency Virus Type 1 Replication and Regulation of APOBEC3G by Peptidyl Prolyl Isomerase Pin1

2008 ◽  
Vol 82 (20) ◽  
pp. 9928-9936 ◽  
Author(s):  
Koichi Watashi ◽  
Mohammad Khan ◽  
Venkat R. K. Yedavalli ◽  
Man Lung Yeung ◽  
Klaus Strebel ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cytidine Deaminase ◽  
Prolyl Isomerase ◽  
Interacting Protein ◽  
New Findings ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT APOBEC3G (A3G) is a cytidine deaminase that restricts human immunodeficiency virus type 1 (HIV-1) replication. HIV-1 synthesizes a viral infectivity factor (Vif) to counter A3G restriction. Currently, it is poorly understood how A3G expression/activity is regulated by cellular factors. Here, we show that the prolyl isomerase Pin1 protein modulates A3G expression. Pin1 was found to be an A3G-interacting protein that reduces A3G expression and its incorporation into HIV-1 virion, thereby limiting A3G-mediated restriction of HIV-1. Intriguingly, HIV-1 infection modulates the phosphorylation state of Pin1, enhancing its ability to moderate A3G activity. These new findings suggest a potential Vif-independent way for HIV-1 to moderate the cellular action of A3G.

scholarly journals Crystal Structures of Zidovudine- or Lamivudine-Resistant Human Immunodeficiency Virus Type 1 Reverse Transcriptases Containing Mutations at Codons 41, 184, and 215

2002 ◽  
Vol 76 (19) ◽  
pp. 10015-10019 ◽  
Author(s):  
P. P. Chamberlain ◽  
J. Ren ◽  
C. E. Nichols ◽  
L. Douglas ◽  
J. Lennerstrand ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Conformational Changes ◽  
Model Building ◽  
Resistance Mutations ◽  
Reverse Transcriptases ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Six structures of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) containing combinations of resistance mutations for zidovudine (AZT) (M41L and T215Y) or lamivudine (M184V) have been determined as inhibitor complexes. Minimal conformational changes in the polymerase or nonnucleoside RT inhibitor sites compared to the mutant RTMC (D67N, K70R, T215F, and K219N) are observed, indicating that such changes may occur only with certain combinations of mutations. Model building M41L and T215Y into HIV-1 RT-DNA and docking in ATP that is utilized in the pyrophosphorolysis reaction for AZT resistance indicates that some conformational rearrangement appears necessary in RT for ATP to interact simultaneously with the M41L and T215Y mutations.

Sign in / Sign up

Export Citation Format

Share Document