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Proceedings of the National Academy of... May 2024Type 1 voltage-activated calcium channels (CaV1) in the plasma membrane trigger calcium release from the sarcoplasmic reticulum (SR) by two mechanisms. In...
Type 1 voltage-activated calcium channels (CaV1) in the plasma membrane trigger calcium release from the sarcoplasmic reticulum (SR) by two mechanisms. In voltage-induced calcium release (VICR), CaV1 voltage sensing domains are directly coupled to ryanodine receptors (RYRs), an SR calcium channel. In calcium-induced calcium release (CICR), calcium ions flowing through activated CaV1 channels bind and activate RYR channels. VICR is thought to occur exclusively in vertebrate skeletal muscle while CICR occurs in all other muscles (including all invertebrate muscles). Here, we use calcium-activated SLO-2 potassium channels to analyze CaV1-SR coupling in body muscles. SLO-2 channels were activated by both VICR and external calcium. VICR-mediated SLO-2 activation requires two SR calcium channels (RYRs and IP3 Receptors), JPH-1/Junctophilin, a PDZ (PSD95, Dlg1, ZO-1 domain) binding domain (PBD) at EGL-19/CaV1's carboxy-terminus, and SHN-1/Shank (a scaffolding protein that binds EGL-19's PBD). Thus, VICR occurs in invertebrate muscles.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Calcium; Ryanodine Receptor Calcium Release Channel; Sarcoplasmic Reticulum; Muscles; Inositol 1,4,5-Trisphosphate Receptors; Large-Conductance Calcium-Activated Potassium Channels; Membrane Proteins; Calcium Signaling; Muscle Proteins; Calcium Channels; Membrane Transport Proteins
PubMed: 38687794
DOI: 10.1073/pnas.2317753121 -
Biosensors Apr 2024The homeostasis of cellular calcium is fundamental for many physiological processes, while the calcium levels remain inhomogeneous within cells. During the onset of...
The homeostasis of cellular calcium is fundamental for many physiological processes, while the calcium levels remain inhomogeneous within cells. During the onset of asthma, epithelial and inflammatory cells secrete platelet-derived growth factor (PDGF), inducing the proliferation and migration of airway smooth muscle (ASM) to the epidermal layer, narrowing the airway. The regulation of ASM cells by PDGF is closely related to the conduction of calcium signals. In this work, we generated subcellular-targeted FRET biosensors to investigate calcium regulation in the different compartments of ASM cells. A PDGF-induced cytoplasmic calcium [Ca] increase was attributed to both extracellular calcium influx and endoplasmic reticulum (ER) calcium [Ca] release, which was partially regulated by the PLC-IPR pathway. Interestingly, the removal of the extracellular calcium influx led to inhibited ER calcium release, likely through inhibitory effects on the calcium-dependent activation of the ER ryanodine receptor. The inhibition of the L-type calcium channel on the plasma membrane or the SERCA pump on the ER resulted in both reduced [Ca] and [Ca] from PDGF stimulation, while IPR channel inhibition led to reduced [Ca] only. The inhibited SERCA pump caused an immediate [Ca] increase and [Ca] decrease, indicating active calcium exchange between the cytosol and ER storage in resting cells. PDGF-induced calcium at the outer mitochondrial membrane sub-region showed a similar regulatory response to cytosolic calcium, not influenced by the inhibition of the mitochondrial calcium uniporter channel. Therefore, our work identifies calcium flow pathways among the extracellular medium, cell cytosol, and ER via regulatory calcium channels. Specifically, extracellular calcium flow has an essential function in fully activating ER calcium release.
Topics: Biosensing Techniques; Platelet-Derived Growth Factor; Calcium; Myocytes, Smooth Muscle; Fluorescence Resonance Energy Transfer; Humans; Endoplasmic Reticulum; Calcium Channels; Calcium Signaling
PubMed: 38667172
DOI: 10.3390/bios14040179 -
Nature Communications Apr 2024Cardiac dysfunction is a hallmark of aging in humans and mice. Here we report that a two-week treatment to restore youthful Bridging Integrator 1 (BIN1) levels in the...
Cardiac dysfunction is a hallmark of aging in humans and mice. Here we report that a two-week treatment to restore youthful Bridging Integrator 1 (BIN1) levels in the hearts of 24-month-old mice rejuvenates cardiac function and substantially reverses the aging phenotype. Our data indicate that age-associated overexpression of BIN1 occurs alongside dysregulated endosomal recycling and disrupted trafficking of cardiac Ca1.2 and type 2 ryanodine receptors. These deficiencies affect channel function at rest and their upregulation during acute stress. In vivo echocardiography reveals reduced systolic function in old mice. BIN1 knockdown using an adeno-associated virus serotype 9 packaged shRNA-mBIN1 restores the nanoscale distribution and clustering plasticity of ryanodine receptors and recovers Ca transient amplitudes and cardiac systolic function toward youthful levels. Enhanced systolic function correlates with increased phosphorylation of the myofilament protein cardiac myosin binding protein-C. These results reveal BIN1 knockdown as a novel therapeutic strategy to rejuvenate the aging myocardium.
Topics: Animals; Adaptor Proteins, Signal Transducing; Male; Aging; Mice; Tumor Suppressor Proteins; Myocardium; Ryanodine Receptor Calcium Release Channel; Gene Knockdown Techniques; Endosomes; Calcium Channels, L-Type; Heart; Mice, Inbred C57BL; Humans; Myocytes, Cardiac; Nuclear Proteins; RNA, Small Interfering; Systole; Nerve Tissue Proteins
PubMed: 38664444
DOI: 10.1038/s41467-024-47847-8 -
BMC Pulmonary Medicine Apr 2024Patients with congenital myopathies may experience respiratory involvement, resulting in restrictive ventilatory dysfunction and respiratory failure. Pulmonary...
BACKGROUND
Patients with congenital myopathies may experience respiratory involvement, resulting in restrictive ventilatory dysfunction and respiratory failure. Pulmonary hypertension (PH) associated with this condition has never been reported in congenital ryanodine receptor type 1(RYR1)-related myopathy.
CASE PRESENTATION
A 47-year-old woman was admitted with progressively exacerbated chest tightness and difficulty in neck flexion. She was born prematurely at week 28. Her bilateral lower extremities were edematous and muscle strength was grade IV. Arterial blood gas analysis revealed hypoventilation syndrome and type II respiratory failure, while lung function test showed restrictive ventilation dysfunction, which were both worse in the supine position. PH was confirmed by right heart catheterization (RHC), without evidence of left heart disease, congenital heart disease, or pulmonary artery obstruction. Polysomnography indicated nocturnal hypoventilation. The ultrasound revealed reduced mobility of bilateral diaphragm. The level of creatine kinase was mildly elevated. Magnetic resonance imaging showed myositis of bilateral thigh muscle. Muscle biopsy of the left biceps brachii suggested muscle malnutrition and congenital muscle disease. Gene testing revealed a missense mutation in the RYR1 gene (exon33 c.C4816T). Finally, she was diagnosed with RYR1-related myopathy and received long-term non-invasive ventilation (NIV) treatment. Her symptoms and cardiopulmonary function have been greatly improved after 10 months.
CONCLUSIONS
We report a case of RYR1-related myopathy exhibiting hypoventilation syndrome, type II respiratory failure and PH associated with restrictive ventilator dysfunction. Pulmonologists should keep congenital myopathies in mind in the differential diagnosis of type II respiratory failure, especially in patients with short stature and muscle weakness.
Topics: Humans; Female; Ryanodine Receptor Calcium Release Channel; Middle Aged; Muscle Weakness; Hypertension, Pulmonary; Respiratory Insufficiency; Mutation, Missense; Magnetic Resonance Imaging; Muscular Diseases
PubMed: 38649898
DOI: 10.1186/s12890-024-03016-7 -
JA Clinical Reports Apr 2024Malignant hyperthermia (MH) is a rare, life-threatening disorder of calcium homeostasis in skeletal muscle cells that is triggered by volatile anesthetics and...
BACKGROUND
Malignant hyperthermia (MH) is a rare, life-threatening disorder of calcium homeostasis in skeletal muscle cells that is triggered by volatile anesthetics and succinylcholine, leading to a hypermetabolic reaction. The pathogenic ryanodine receptor 1 (RYR1) gene variant is critical. Patients susceptible to MH should avoid triggering agents, and total intravenous anesthesia (TIVA) is preferred. Remimazolam is safe in patients with suspected MH.
CASE PRESENTATION
We present the first case of remimazolam treatment in a genetically confirmed patient with MH without MH development. A 72-year-old man with a family history of MH underwent remimazolam-based TIVA. After informed consent was obtained, a muscle biopsy and genetic testing were performed. Intraoperatively and postoperatively, the patient exhibited no signs of MH. An enhanced function of the RYR1 channel into releasing calcium was indicated, and the genetic testing revealed a pathogenic variant of RYR1.
CONCLUSIONS
Remimazolam-based TIVA is safe in patients confirming the diagnosis of MH.
PubMed: 38647904
DOI: 10.1186/s40981-024-00710-7 -
IScience May 2024Glucagon is secreted by pancreatic α-cells to counteract hypoglycaemia. How glucose regulates glucagon secretion remains unclear. Here, using mouse islets, we studied...
Glucagon is secreted by pancreatic α-cells to counteract hypoglycaemia. How glucose regulates glucagon secretion remains unclear. Here, using mouse islets, we studied the role of transmembrane and endoplasmic reticulum (ER) Ca on intrinsic α-cell glucagon secretion. Blocking isradipine-sensitive L-type voltage-gated Ca (Ca) channels abolished α-cell electrical activity but had little impact on its cytosolic Ca oscillations or low-glucose-stimulated glucagon secretion. In contrast, depleting ER Ca with cyclopiazonic acid or blocking ER Ca-releasing ryanodine receptors abolished α-cell glucose sensitivity and low-glucose-stimulated glucagon secretion. ER Ca mobilization in α-cells is regulated by intracellular ATP and likely to be coupled to Ca influx through P/Q-type Ca channels. ω-Agatoxin IVA blocked α-cell ER Ca release and cell exocytosis, but had no additive effect on glucagon secretion when combined with ryanodine. We conclude that glucose regulates glucagon secretion through the control of ER Ca mobilization, a mechanism that can be independent of α-cell electrical activity.
PubMed: 38646167
DOI: 10.1016/j.isci.2024.109665 -
Chemical & Pharmaceutical Bulletin 2024Ryanodine receptor 2 (RyR2) is a large Ca-release channel in the sarcoplasmic reticulum (SR) of cardiac muscle cells. It serves to release Ca from the SR into the...
Ryanodine receptor 2 (RyR2) is a large Ca-release channel in the sarcoplasmic reticulum (SR) of cardiac muscle cells. It serves to release Ca from the SR into the cytosol to initiate muscle contraction. RyR2 overactivation is associated with arrhythmogenic cardiac disease, but few specific inhibitors have been reported so far. Here, we identified an RyR2-selective inhibitor 1 from the chemical compound library and synthesized it from glycolic acid. Synthesis of various derivatives to investigate the structure-activity relationship of each substructure afforded another two RyR2-selective inhibitors 6 and 7, among which 6 was the most potent. Notably, compound 6 also inhibited Ca release in cells expressing the RyR2 mutants R2474S, R4497C and K4750Q, which are associated with cardiac arrhythmias such as catecholaminergic polymorphic ventricular tachycardia (CPVT). This inhibitor is expected to be a useful tool for research on the structure and dynamics of RyR2, as well as a lead compound for the development of drug candidates to treat RyR2-related cardiac disease.
Topics: Humans; Calcium; Dose-Response Relationship, Drug; Drug Discovery; HEK293 Cells; Molecular Structure; Ryanodine Receptor Calcium Release Channel; Structure-Activity Relationship; Calcium Channel Blockers; Anti-Arrhythmia Agents; Tachycardia, Ventricular
PubMed: 38644198
DOI: 10.1248/cpb.c24-00114 -
ESC Heart Failure Apr 2024Hyperactivity of Ca/calmodulin-dependent protein kinase II (CaMKII) has emerged as a central cause of pathologic remodelling in heart failure. It has been suggested that...
AIMS
Hyperactivity of Ca/calmodulin-dependent protein kinase II (CaMKII) has emerged as a central cause of pathologic remodelling in heart failure. It has been suggested that CaMKII-induced hyperphosphorylation of the ryanodine receptor 2 (RyR2) and consequently increased diastolic Ca leak from the sarcoplasmic reticulum (SR) is a crucial mechanism by which increased CaMKII activity leads to contractile dysfunction. We aim to evaluate the relevance of CaMKII-dependent RyR2 phosphorylation for CaMKII-induced heart failure development in vivo.
METHODS AND RESULTS
We crossbred CaMKIIδC overexpressing [transgenic (TG)] mice with RyR2-S2814A knock-in mice that are resistant to CaMKII-dependent RyR2 phosphorylation. Ca-spark measurements on isolated ventricular myocytes confirmed the severe diastolic SR Ca leak previously reported in CaMKIIδC TG [4.65 ± 0.73 mF/F vs. 1.88 ± 0.30 mF/F in wild type (WT)]. Crossing in the S2814A mutation completely prevented SR Ca-leak induction in the CaMKIIδC TG, both regarding Ca-spark size and frequency, demonstrating that the CaMKIIδC-induced SR Ca leak entirely depends on the CaMKII-specific RyR2-S2814 phosphorylation. Yet, the RyR2-S2814A mutation did not affect the massive contractile dysfunction (ejection fraction = 12.17 ± 2.05% vs. 45.15 ± 3.46% in WT), cardiac hypertrophy (heart weight/tibia length = 24.84 ± 3.00 vs. 9.81 ± 0.50 mg/mm in WT), or severe premature mortality (median survival of 12 weeks) associated with cardiac CaMKIIδC overexpression. In the face of a prevented SR Ca leak, the phosphorylation status of other critical CaMKII downstream targets that can drive heart failure, including transcriptional regulator histone deacetylase 4, as well as markers of pathological gene expression including Xirp2, Il6, and Col1a1, was equally increased in hearts from CaMKIIδC TG on a RyR WT and S2814A background.
CONCLUSIONS
S2814 phosphoresistance of RyR2 prevents the CaMKII-dependent SR Ca leak induction but does not prevent the cardiomyopathic phenotype caused by enhanced CaMKIIδC activity. Our data indicate that additional mechanisms-independent of SR Ca leak-are critical for the maladaptive effects of chronically increased CaMKIIδC activity with respect to heart failure.
PubMed: 38616546
DOI: 10.1002/ehf2.14772 -
Cells Apr 2024During pregnancy, uterine vasculature undergoes significant circumferential growth to increase uterine blood flow, vital for the growing feto-placental unit. However,...
During pregnancy, uterine vasculature undergoes significant circumferential growth to increase uterine blood flow, vital for the growing feto-placental unit. However, this process is often compromised in conditions like maternal high blood pressure, particularly in preeclampsia (PE), leading to fetal growth impairment. Currently, there is no cure for PE, partly due to the adverse effects of anti-hypertensive drugs on maternal and fetal health. This study aimed to investigate the vasodilator effect of extra virgin olive oil (EVOO) phenols on the reproductive vasculature, potentially benefiting both mother and fetus. Isolated uterine arteries (UAs) from pregnant rats were tested with EVOO phenols in a pressurized myograph. To elucidate the underlying mechanisms, additional experiments were conducted with specific inhibitors: L-NAME/L-NNA (10 M) for nitric oxide synthases, ODQ (10 M) for guanylate cyclase, Verapamil (10 M) for the L-type calcium channel, Ryanodine (10 M) + 2-APB (3 × 10 M) for ryanodine and the inositol triphosphate receptors, respectively, and Paxilline (10 M) for the large-conductance calcium-activated potassium channel. The results indicated that EVOO-phenols activate Ca signaling pathways, generating nitric oxide, inducing vasodilation via cGMP and BKCa signals in smooth muscle cells. This study suggests the potential use of EVOO phenols to prevent utero-placental blood flow restriction, offering a promising avenue for managing PE.
Topics: Rats; Pregnancy; Female; Animals; Uterine Artery; Calcium; Olive Oil; Nitric Oxide; Placenta; Ryanodine; Phenols; Dilatation; Large-Conductance Calcium-Activated Potassium Channels; Endothelium
PubMed: 38607058
DOI: 10.3390/cells13070619 -
Stem Cell Research Jun 2024RYR1 variants are the most common genetic cause of congenital myopathies, and typically cause central core disease (CCD) and/or malignant hyperthermia (MH). Here, we...
Generation of two iPSC lines from patients with inherited central core disease and concurrent malignant hyperthermia caused by dominant missense variants in the RYR1 gene.
RYR1 variants are the most common genetic cause of congenital myopathies, and typically cause central core disease (CCD) and/or malignant hyperthermia (MH). Here, we generated iPSC lines from two patients with CCD and MH caused by dominant RYR1 variants within the central region of the protein (p.Val2168Met and p.Arg2508Cys). Both lines displayed typical iPSC morphology, uniform expression of pluripotency markers, trilineage differentiation potential, and had normal karyotypes. These are the first RYR1 iPSC lines from patients with both CCD and MH. As these are common CCD/MH variants, these lines should be useful to study these conditions and test therapeutics.
Topics: Humans; Ryanodine Receptor Calcium Release Channel; Malignant Hyperthermia; Induced Pluripotent Stem Cells; Mutation, Missense; Myopathy, Central Core; Male; Female; Cell Line; Cell Differentiation
PubMed: 38583293
DOI: 10.1016/j.scr.2024.103410