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Thermoregulation is an important aspect of human homeostasis, and high temperatures pose serious stresses for the body. Malignant hyperthermia (MH) is a life-threatening disorder in which body temperature can rise to a lethal level. Here we employ an optically controlled local heat-pulse method to manipulate the temperature in cells with a precision of less than 1 °C and find that the mutants of ryanodine receptor type 1 (RyR1), a key Ca release channel underlying MH, are heat hypersensitive compared with the wild type (WT). We show that the local heat pulses induce an intracellular Ca burst in human embryonic kidney 293 cells overexpressing WT RyR1 and some RyR1 mutants related to MH. Fluorescence Ca imaging using the endoplasmic reticulum-targeted fluorescent probes demonstrates that the Ca burst originates from heat-induced Ca release (HICR) through RyR1-mutant channels because of the channels' heat hypersensitivity. Furthermore, the variation in the heat hypersensitivity of four RyR1 mutants highlights the complexity of MH. HICR likewise occurs in skeletal muscles of MH model mice. We propose that HICR contributes an additional positive feedback to accelerate thermogenesis in patients with MH.
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http://dx.doi.org/10.1073/pnas.2201286119 | DOI Listing |
Nat Cardiovasc Res
August 2025
Department of Medicine, Division of Cardiovascular Medicine, and Cardiovascular Research Center, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA.
Phosphorylation of specific sites in ryanodine receptor 2 (RyR2), a major cardiac Ca channel, increases channel activity and promotes pathological sarcoplasmic reticulum Ca leak and arrhythmia. RyR2 is phosphorylated during adrenergic stimulation, but the role of this phosphorylation remains debated. In this study, we generated a mouse model with phospho-ablation of the three canonical phosphorylation sites in RyR2 (S2031A/S2808A/S2814A, triple phospho-mutant (TPM)) to determine their role in the adrenergic response.
View Article and Find Full Text PDFProg Lipid Res
July 2025
RMovAnt Research Group, Department of Rehabilitation Sciences & Physiotherapy, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium; Exercise Physiology Research Group, Department of Movement Sciences, University of Leuven, Tervuursevest 101, 3001 Leuven, Belgium. Electronic address: S
Malignant hyperthermia (MH) is a life-threatening pharmacogenetic disorder triggered by volatile anaesthetics and depolarizing muscle relaxants. MH is characterized by excessive calcium release from the sarcoplasmic reticulum, often due to ryanodine receptor 1 (RYR1) mutations, leading to hypermetabolism, muscle rigidity and hyperthermia. While the RYR1 antagonist dantrolene remains the primary pharmacological treatment, its side effects necessitate exploration of alternative treatment options.
View Article and Find Full Text PDFAdv Exp Med Biol
July 2025
Molecular Entomology Laboratory, Faculty of Agriculture, Department of Plant Protection Ankara, Ankara University, Ankara, Türkiye.
Calcium (Ca) homeostasis is a critical regulator of insect cellular functions, influencing neurotransmission, muscle contraction, hormone signaling, and lipid metabolism. This chapter explores the intricate relationship between Ca signaling and lipid metabolism, emphasizing key molecular components that mediate this interaction. Store-operated calcium entry (SOCE) mechanisms, involving sarco/endoplasmic reticulum Ca-ATPase (SERCA), inositol 1,4,5-trisphosphate receptor (IPR), ryanodine receptor (RyR), stromal interaction molecule (STIM), and Orai1, coordinate intracellular Ca fluxes that regulate lipid storage, mobilization, and utilization.
View Article and Find Full Text PDFNat Cardiovasc Res
July 2025
QIMR Berghofer, Brisbane, Queensland, Australia.
Maturation of human pluripotent stem (hPS) cell-derived cardiomyocytes is critical for their use as a model system. Here we mimic human heart maturation pathways in the setting of hPS cell-derived cardiac organoids (hCOs). Specifically, transient activation of 5' AMP-activated protein kinase and estrogen-related receptor enhanced cardiomyocyte maturation, inducing expression of mature sarcomeric and oxidative phosphorylation proteins, and increasing metabolic capacity.
View Article and Find Full Text PDFPLoS Biol
June 2025
Department of Systems Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Inhaled anesthetics were first introduced into clinical use in the 1840s. Molecular and transgenic animal studies indicate that inhaled anesthetics act through several ion channels, including γ-aminobutyric acid type A receptors (GABAARs) and two-pore domain K+ (K2P) channels, but other targets may mediate anesthetic effects. Mutations in the type 1 ryanodine receptor (RyR1), which is a calcium release channel on the endoplasmic reticulum membrane, are relevant to malignant hyperthermia, a condition that can be induced by inhaled anesthetics.
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