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Feng W, Lopez JR, Antrobus S, Zheng J, Uryash A, Dong Y, Beqollari D, Bannister RA, Hopkins PM, Beam KG, Allen PD, Pessah IN. Putative malignant hyperthermia mutation Ca V1.1-R174W is insufficient to trigger a fulminant response to halothane or confer heat stress intolerance. J Biol Chem 2023; 299:104992. [PMID: 37392848 PMCID: PMC10413282 DOI: 10.1016/j.jbc.2023.104992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/16/2023] [Accepted: 06/20/2023] [Indexed: 07/03/2023] Open
Abstract
Malignant hyperthermia susceptibility (MHS) is an autosomal dominant pharmacogenetic disorder that manifests as a hypermetabolic state when carriers are exposed to halogenated volatile anesthetics or depolarizing muscle relaxants. In animals, heat stress intolerance is also observed. MHS is linked to over 40 variants in RYR1 that are classified as pathogenic for diagnostic purposes. More recently, a few rare variants linked to the MHS phenotype have been reported in CACNA1S, which encodes the voltage-activated Ca2+ channel CaV1.1 that conformationally couples to RyR1 in skeletal muscle. Here, we describe a knock-in mouse line that expresses one of these putative variants, CaV1.1-R174W. Heterozygous (HET) and homozygous (HOM) CaV1.1-R174W mice survive to adulthood without overt phenotype but fail to trigger with fulminant malignant hyperthermia when exposed to halothane or moderate heat stress. All three genotypes (WT, HET, and HOM) express similar levels of CaV1.1 by quantitative PCR, Western blot, [3H]PN200-110 receptor binding and immobilization-resistant charge movement densities in flexor digitorum brevis fibers. Although HOM fibers have negligible CaV1.1 current amplitudes, HET fibers have similar amplitudes to WT, suggesting a preferential accumulation of the CaV1.1-WT protein at triad junctions in HET animals. Never-the-less both HET and HOM have slightly elevated resting free Ca2+ and Na+ measured with double barreled microelectrode in vastus lateralis that is disproportional to upregulation of transient receptor potential canonical (TRPC) 3 and TRPC6 in skeletal muscle. CaV1.1-R174W and upregulation of TRPC3/6 alone are insufficient to trigger fulminant malignant hyperthermia response to halothane and/or heat stress in HET and HOM mice.
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Affiliation(s)
- Wei Feng
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA
| | - Jose R Lopez
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA; Department of Research, Mount Sinai Medical Center, Miami Beach, Florida, USA
| | - Shane Antrobus
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA
| | - Jing Zheng
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA
| | - Arkady Uryash
- Department of Research, Mount Sinai Medical Center, Miami Beach, Florida, USA
| | - Yao Dong
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA
| | - Donald Beqollari
- Department of Medicine-Cardiology Division, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Roger A Bannister
- Department of Medicine-Cardiology Division, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Philip M Hopkins
- Institute of Medical Research at St James's, University of Leeds, Leeds, United Kingdom
| | - Kurt G Beam
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Paul D Allen
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA; Institute of Medical Research at St James's, University of Leeds, Leeds, United Kingdom
| | - Isaac N Pessah
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA.
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Klocke B, Krone K, Tornes J, Moore C, Ott H, Pitychoutis PM. Insights into the role of intracellular calcium signaling in the neurobiology of neurodevelopmental disorders. Front Neurosci 2023; 17:1093099. [PMID: 36875674 PMCID: PMC9975342 DOI: 10.3389/fnins.2023.1093099] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/27/2023] [Indexed: 02/17/2023] Open
Abstract
Calcium (Ca2+) comprises a critical ionic second messenger in the central nervous system that is under the control of a wide array of regulatory mechanisms, including organellar Ca2+ stores, membrane channels and pumps, and intracellular Ca2+-binding proteins. Not surprisingly, disturbances in Ca2+ homeostasis have been linked to neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. However, aberrations in Ca2+ homeostasis have also been implicated in neuropsychiatric disorders with a strong neurodevelopmental component including autism spectrum disorder (ASD) attention-deficit hyperactivity disorder (ADHD) and schizophrenia (SCZ). While plasma membrane Ca2+ channels and synaptic Ca2+-binding proteins have been extensively studied, increasing evidence suggests a prominent role for intracellular Ca2+ stores, such as the endoplasmic reticulum (ER), in aberrant neurodevelopment. In the context of the current mini-review, we discuss recent findings implicating critical intracellular Ca2+-handling regulators such as the sarco-ER Ca2+ ATPase 2 (SERCA2), ryanodine receptors (RyRs), inositol triphosphate receptors (IP3Rs), and parvalbumin (PVALB), in the emergence of ASD, SCZ, and ADHD.
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Affiliation(s)
- Benjamin Klocke
- Department of Biology, University of Dayton, Dayton, OH, United States
| | - Kylie Krone
- Department of Biology, University of Dayton, Dayton, OH, United States
| | - Jason Tornes
- Department of Biology, University of Dayton, Dayton, OH, United States
| | - Carter Moore
- Department of Biology, University of Dayton, Dayton, OH, United States
| | - Hayden Ott
- Department of Biology, University of Dayton, Dayton, OH, United States
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Keil-Stietz K, Lein PJ. Gene×environment interactions in autism spectrum disorders. Curr Top Dev Biol 2022; 152:221-284. [PMID: 36707213 PMCID: PMC10496028 DOI: 10.1016/bs.ctdb.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
There is credible evidence that environmental factors influence individual risk and/or severity of autism spectrum disorders (hereafter referred to as autism). While it is likely that environmental chemicals contribute to the etiology of autism via multiple mechanisms, identifying specific environmental factors that confer risk for autism and understanding how they contribute to the etiology of autism has been challenging, in part because the influence of environmental chemicals likely varies depending on the genetic substrate of the exposed individual. Current research efforts are focused on elucidating the mechanisms by which environmental chemicals interact with autism genetic susceptibilities to adversely impact neurodevelopment. The goal is to not only generate insights regarding the pathophysiology of autism, but also inform the development of screening platforms to identify specific environmental factors and gene×environment (G×E) interactions that modify autism risk. Data from such studies are needed to support development of intervention strategies for mitigating the burden of this neurodevelopmental condition on individuals, their families and society. In this review, we discuss environmental chemicals identified as putative autism risk factors and proposed mechanisms by which G×E interactions influence autism risk and/or severity using polychlorinated biphenyls (PCBs) as an example.
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Affiliation(s)
- Kimberly Keil-Stietz
- Department of Comparative Biosciences, University of Wisconsin-Madison, School of Veterinary Medicine, Madison, WI, United States
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, United States.
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White R, Schiemann AH, Burling SM, Bjorksten A, Bulger T, Gillies R, Hopkins PM, Kamsteeg EJ, Machon RG, Massey S, Miller D, Perry M, Snoeck MM, Stephens J, Street N, van den Bersselaar LR, Stowell KM. Functional analysis of RYR1 variants in patients with confirmed susceptibility to malignant hyperthermia. Br J Anaesth 2022; 129:879-888. [DOI: 10.1016/j.bja.2022.08.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 11/02/2022] Open
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Keil Stietz KP, Sethi S, Klocke CR, de Ruyter TE, Wilson MD, Pessah IN, Lein PJ. Sex and Genotype Modulate the Dendritic Effects of Developmental Exposure to a Human-Relevant Polychlorinated Biphenyls Mixture in the Juvenile Mouse. Front Neurosci 2021; 15:766802. [PMID: 34924936 PMCID: PMC8678536 DOI: 10.3389/fnins.2021.766802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/04/2021] [Indexed: 11/23/2022] Open
Abstract
While many neurodevelopmental disorders (NDDs) are thought to result from interactions between environmental and genetic risk factors, the identification of specific gene-environment interactions that influence NDD risk remains a critical data gap. We tested the hypothesis that polychlorinated biphenyls (PCBs) interact with human mutations that alter the fidelity of neuronal Ca2+ signaling to confer NDD risk. To test this, we used three transgenic mouse lines that expressed human mutations known to alter Ca2+ signals in neurons: (1) gain-of-function mutation in ryanodine receptor-1 (T4826I-RYR1); (2) CGG-repeat expansion in the 5′ non-coding portion of the fragile X mental retardation gene 1 (FMR1); and (3) a double mutant (DM) that expressed both mutations. Transgenic and wildtype (WT) mice were exposed throughout gestation and lactation to the MARBLES PCB mix at 0.1, 1, or 6 mg/kg in the maternal diet. The MARBLES mix simulates the relative proportions of the twelve most abundant PCB congeners found in serum from pregnant women at increased risk for having a child with an NDD. Using Golgi staining, the effect of developmental PCB exposure on dendritic arborization of pyramidal neurons in the CA1 hippocampus and somatosensory cortex of male and female WT mice was compared to pyramidal neurons from transgenic mice. A multilevel linear mixed-effects model identified a main effect of dose driven by increased dendritic arborization of cortical neurons in the 1 mg/kg PCB dose group. Subsequent analyses with genotypes indicated that the MARBLES PCB mixture had no effect on the dendritic arborization of hippocampal neurons in WT mice of either sex, but significantly increased dendritic arborization of cortical neurons of WT males in the 6 mg/kg PCB dose group. Transgene expression increased sensitivity to the impact of developmental PCB exposure on dendritic arborization in a sex-, and brain region-dependent manner. In conclusion, developmental exposure to PCBs present in the gestational environment of at-risk humans interfered with normal dendritic morphogenesis in the developing mouse brain in a sex-, genotype- and brain region-dependent manner. Overall, these observations provide proof-of-principle evidence that PCBs interact with heritable mutations to modulate a neurodevelopmental outcome of relevance to NDDs.
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Affiliation(s)
- Kimberly P Keil Stietz
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Sunjay Sethi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Carolyn R Klocke
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Tryssa E de Ruyter
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Machelle D Wilson
- Clinical and Translational Science Center, Division of Biostatistics, Department of Public Health Sciences, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
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Sethi S, Keil Stietz KP, Valenzuela AE, Klocke CR, Silverman JL, Puschner B, Pessah IN, Lein PJ. Developmental Exposure to a Human-Relevant Polychlorinated Biphenyl Mixture Causes Behavioral Phenotypes That Vary by Sex and Genotype in Juvenile Mice Expressing Human Mutations That Modulate Neuronal Calcium. Front Neurosci 2021; 15:766826. [PMID: 34938155 PMCID: PMC8685320 DOI: 10.3389/fnins.2021.766826] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/17/2021] [Indexed: 01/13/2023] Open
Abstract
Polychlorinated biphenyls (PCBs) are putative environmental risks for neurodevelopmental disorders. Here, we tested two hypotheses: (1) developmental exposure to a human-relevant PCB mixture causes behavioral phenotypes relevant to neurodevelopmental disorders; and (2) expression of human mutations that dysregulate neuronal Ca2+ homeostasis influence sensitivity to behavioral effects of developmental PCB exposures. To test these hypotheses, we used mice that expressed a gain-of-function mutation (T4826I) in ryanodine receptor 1 (RYR1), the X-linked fragile X mental retardation 1 (FMR1) CGG repeat expansion or both mutations (double mutant; DM). Transgenic mice and wildtype (WT) mice were exposed to the MARBLES PCB mix at 0, 0.1, 1, and 6 mg/kg/day in the maternal diet throughout gestation and lactation. The MARBLES PCB mix simulates the relative proportions of the 12 most abundant PCB congeners found in the serum of pregnant women at increased risk for having a child with a neurodevelopmental disorder. We assessed ultrasonic vocalizations at postnatal day 7 (P7), spontaneous repetitive behaviors at P25-P30, and sociability at P27-P32. Developmental PCB exposure reduced ultrasonic vocalizations in WT litters in all dose groups, but had no effect on ultrasonic vocalizations in transgenic litters. Developmental PCB exposure significantly increased self-grooming and decreased sociability in WT males in the 0.1 mg/kg dose group, but had no effect on WT females in any dose group. Genotype alone influenced ultrasonic vocalizations, self-grooming and to a lesser extent sociability. Genotype alone also influenced effects of PCBs on sociability. PCB levels in the brain tissue of pups increased in a dose-dependent manner, but within any dose group did not differ between genotypes. In summary, developmental PCB exposure phenocopied social behavior phenotypes observed in mice expressing human mutations that modify intracellular Ca2+ dynamics, and expression of these mutations alleviated PCB effects on ultrasonic vocalizations and repetitive behavior, and modified the dose-response relationships and sex-dependent effects of PCB effects on social behavior. These findings suggest that: (1) developmental PCB exposure causes behavioral phenotypes that vary by sex and genotype; and (2) sex-specific responses to environmental factors may contribute to sex biases in the prevalence and/or severity of neurodevelopmental disorders.
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Affiliation(s)
- Sunjay Sethi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Kimberly P. Keil Stietz
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Anthony E. Valenzuela
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Carolyn R. Klocke
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Jill L. Silverman
- Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California, Davis, Davis, CA, United States
- The MIND Institute, University of California, Davis, Davis, CA, United States
| | - Birgit Puschner
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Isaac N. Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
- The MIND Institute, University of California, Davis, Davis, CA, United States
| | - Pamela J. Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
- The MIND Institute, University of California, Davis, Davis, CA, United States
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7
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T lymphocytes from malignant hyperthermia-susceptible mice display aberrations in intracellular calcium signaling and mitochondrial function. Cell Calcium 2020; 93:102325. [PMID: 33310301 DOI: 10.1016/j.ceca.2020.102325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 01/05/2023]
Abstract
Gain-of-function RyR1-p.R163C mutation in ryanodine receptors type 1 (RyR1) deregulates Ca2+ signaling and mitochondrial function in skeletal muscle and causes malignant hyperthermia in humans and mice under triggering conditions. We investigated whether T lymphocytes from heterozygous RyR1-p.R163C knock-in mutant mice (HET T cells) display measurable aberrations in resting cytosolic Ca2+ concentration ([Ca2+]i), Ca2+ release from the store, store-operated Ca2+ entry (SOCE), and mitochondrial inner membrane potential (ΔΨm) compared with T lymphocytes from wild-type mice (WT T cells). We explored whether these variables can be used to distinguish between T cells with normal and altered RyR1 genotype. HET and WT T cells were isolated from spleen and lymph nodes and activated in vitro using phytohemagglutinin P. [Ca2+]i and ΔΨm dynamics were examined using Fura 2 and tetramethylrhodamine methyl ester fluorescent dyes, respectively. Activated HET T cells displayed elevated resting [Ca2+]i, diminished responses to Ca2+ mobilization with thapsigargin, and decreased rate of [Ca2+]i elevation in response to SOCE compared with WT T cells. Pretreatment of HET T cells with ryanodine or dantrolene sodium reduced disparities in the resting [Ca2+]i and ability of thapsigargin to mobilize Ca2+ between HET and WT T cells. While SOCE elicited dissipation of the ΔΨm in WT T cells, it produced ΔΨm hyperpolarization in HET T cells. When used as the classification variable, the amplitude of thapsigargin-induced Ca2+ transient showed the best promise in predicting the presence of RyR1-p.R163C mutation. Other significant variables identified by machine learning analysis were the ratio of resting cytosolic Ca2+ level to the amplitude of thapsigargin-induced Ca2+ transient and an integral of changes in ΔΨm in response to SOCE. Our study demonstrated that gain-of-function mutation in RyR1 significantly affects Ca2+ signaling and mitochondrial fiction in T lymphocytes, which suggests that this mutation may cause altered immune responses in its carrier. Our data link the RyR1-p.R163C mutation, which causes inherited skeletal muscle diseases, to deregulation of Ca2+ signaling and mitochondrial function in immune T cells and establish proof-of-principle for in vitro T cell-based diagnostic assay for hereditary RyR1 hyperfunction.
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Polychlorinated Biphenyls (PCBs): Risk Factors for Autism Spectrum Disorder? TOXICS 2020; 8:toxics8030070. [PMID: 32957475 PMCID: PMC7560399 DOI: 10.3390/toxics8030070] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/14/2020] [Accepted: 09/16/2020] [Indexed: 02/06/2023]
Abstract
Autism spectrum disorder (ASD) includes a group of multifactorial neurodevelopmental disorders defined clinically by core deficits in social reciprocity and communication, restrictive interests and repetitive behaviors. ASD affects one in 54 children in the United States, one in 89 children in Europe, and one in 277 children in Asia, with an estimated worldwide prevalence of 1-2%. While there is increasing consensus that ASD results from complex gene x environment interactions, the identity of specific environmental risk factors and the mechanisms by which environmental and genetic factors interact to determine individual risk remain critical gaps in our understanding of ASD etiology. Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that have been linked to altered neurodevelopment in humans. Preclinical studies demonstrate that PCBs modulate signaling pathways implicated in ASD and phenocopy the effects of ASD risk genes on critical morphometric determinants of neuronal connectivity, such as dendritic arborization. Here, we review human and experimental evidence identifying PCBs as potential risk factors for ASD and discuss the potential for PCBs to influence not only core symptoms of ASD, but also comorbidities commonly associated with ASD, via effects on the central and peripheral nervous systems, and/or peripheral target tissues, using bladder dysfunction as an example. We also discuss critical data gaps in the literature implicating PCBs as ASD risk factors. Unlike genetic factors, which are currently irreversible, environmental factors are modifiable risks. Therefore, data confirming PCBs as risk factors for ASD may suggest rational approaches for the primary prevention of ASD in genetically susceptible individuals.
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Matelski L, Keil Stietz KP, Sethi S, Taylor SL, Van de Water J, Lein PJ. The influence of sex, genotype, and dose on serum and hippocampal cytokine levels in juvenile mice developmentally exposed to a human-relevant mixture of polychlorinated biphenyls. Curr Res Toxicol 2020; 1:85-103. [PMID: 34296199 PMCID: PMC8294704 DOI: 10.1016/j.crtox.2020.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Polychlorinated biphenyls (PCBs) are pervasive environmental contaminants implicated as risk factors for neurodevelopmental disorders (NDDs). Immune dysregulation is another NDD risk factor, and developmental PCB exposures are associated with early life immune dysregulation. Studies of the immunomodulatory effects of PCBs have focused on the higher-chlorinated congeners found in legacy commercial mixtures. Comparatively little is known about the immune effects of contemporary, lower-chlorinated PCBs. This is a critical data gap given recent reports that lower-chlorinated congeners comprise >70% of the total PCB burden in serum of pregnant women enrolled in the MARBLES study who are at increased risk for having a child with an NDD. To examine the influence of PCBs, sex, and genotype on cytokine levels, mice were exposed throughout gestation and lactation to a PCB mixture in the maternal diet, which was based on the 12 most abundant PCBs in sera from MARBLES subjects. Using multiplex array, cytokines were quantified in the serum and hippocampus of weanling mice expressing either a human gain-of-function mutation in ryanodine receptor 1 (T4826I mice), a human CGG premutation repeat expansion in the fragile X mental retardation gene 1 (CGG mice), or both mutations (DM mice). Congenic wildtype (WT) mice were used as controls. There were dose-dependent effects of PCB exposure on cytokine concentrations in the serum but not hippocampus. Differential effects of genotype were observed in the serum and hippocampus. Hippocampal cytokines were consistently elevated in T4826I mice and also in WT animals for some cytokines compared to CGG and DM mice, while serum cytokines were usually elevated in the mutant genotypes compared to the WT group. Males had elevated levels of 19 cytokines in the serum and 4 in the hippocampus compared to females, but there were also interactions between sex and genotype for 7 hippocampal cytokines. Only the chemokine CCL5 in the serum showed an interaction between PCB dose, genotype, and sex. Collectively, these findings indicate differential influences of PCB exposure and genotype on cytokine levels in serum and hippocampal tissue of weanling mice. These results suggest that developmental PCB exposure has chronic effects on baseline serum, but not hippocampal, cytokine levels in juvenile mice.
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Affiliation(s)
- Lauren Matelski
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA
| | - Kimberly P. Keil Stietz
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA
| | - Sunjay Sethi
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA
| | - Sandra L. Taylor
- Division of Biostatistics, Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, CA 95616, USA
| | - Judy Van de Water
- MIND Institute, University of California, Davis, School of Medicine, Sacramento, CA 95817, USA,Division of Rheumatology, Allergy, and Clinical Immunology, Department of Internal Medicine, University of California, Davis, School of Medicine, Davis, CA 95616, USA
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA,MIND Institute, University of California, Davis, School of Medicine, Sacramento, CA 95817, USA,Corresponding author at: Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, 1089 Veterinary Medicine Drive, Davis, CA 95616, USA.
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Chang L, Liu X, Diggle CP, Boyle JP, Hopkins PM, Shaw MA, Allen PD. Bioenergetic defects in muscle fibers of RYR1 mutant knock-in mice associated with malignant hyperthermia. J Biol Chem 2020; 295:15226-15235. [PMID: 32826313 DOI: 10.1074/jbc.ra120.013537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/16/2020] [Indexed: 12/14/2022] Open
Abstract
Mutations in the skeletal muscle ryanodine receptor gene (RYR1) can cause susceptibility to malignant hyperthermia (MH), a potentially lethal genetic condition triggered by volatile anesthetics. MH is associated with hypermetabolism, which has directed research interest into oxidative phosphorylation and muscle bioenergetics. The most common cause of MH in the United Kingdom is the c.7300G>A RYR1 variant, which is present in ∼16% of MH families. Our study focuses on the MH susceptible G2435R-RYR1 knock-in mouse model, which is the murine equivalent of the human c.7300G>A genotype. Using a combination of transcriptomics, protein expression, and functional analysis, we investigated adult muscle fiber bioenergetics in this mouse model. RNA-Seq data showed reduced expression of genes associated with mitochondria and fatty acid oxidation in RYR1 mutants when compared with WT controls. Mitochondrial function was assessed by measuring oxygen consumption rates in permeabilized muscle fibers. Comparisons between WT and homozygous G2435R-RYR1 mitochondria showed a significant increase in complex I-facilitated oxidative phosphorylation in mutant muscle. Furthermore, we observed a gene-dose-specific increase in reactive oxygen species production in G2435R-RYR1 muscle fibers. Collectively, these findings provide evidence of metabolic defects in G2435R-RYR1 knock-in mouse muscle under basal conditions. Differences in metabolic profile could be the result of differential gene expression in metabolic pathways, in conjunction with mitochondrial damage accumulated from chronic exposure to increased oxidative stress.
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Affiliation(s)
- Leon Chang
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom
| | - Xiaochen Liu
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom
| | - Christine P Diggle
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom
| | - John P Boyle
- Leeds Institute of Cardiovascular & Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | - Philip M Hopkins
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom; Malignant Hyperthermia Unit, St James's University Hospital, Leeds, United Kingdom
| | - Marie-Anne Shaw
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom
| | - Paul D Allen
- Leeds Institute of Medical Research at St. James's, University of Leeds, Leeds, United Kingdom.
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Aleman M, Zhang R, Feng W, Qi L, Lopez JR, Crowe C, Dong Y, Cherednichenko G, Pessah IN. Dietary Caffeine Synergizes Adverse Peripheral and Central Responses to Anesthesia in Malignant Hyperthermia Susceptible Mice. Mol Pharmacol 2020; 98:351-363. [PMID: 32764093 DOI: 10.1124/mol.120.119412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 07/31/2020] [Indexed: 11/22/2022] Open
Abstract
Ryanodine receptor (RYR) mutations confer stress-triggered malignant hyperthermia (MH) susceptibility. Dietary caffeine (CAF) is the most commonly consumed psychoactive compound by humans. CAF-triggered Ca2+ release and its influences on skeletal muscle contractility are widely used as experimental tools to study RYR function/dysfunction and diagnose MH susceptibility. We hypothesize that dietary CAF achieving blood levels measured in human plasma exacerbates the penetrance of RYR1 MH susceptibility mutations triggered by gaseous anesthetic, affecting both central and peripheral adverse responses. Heterozygous R163C-RYR1 (HET) MH susceptible mice are used to investigate the influences of dietary CAF on both peripheral and central responses before and after induction of halothane (HAL) maintenance anesthesia under experimental conditions that maintain normal core body temperature. HET mice receiving CAF (plasma CAF 893 ng/ml) have significantly shorter times to respiratory arrest compared with wild type, without altering blood chemistry or displaying hyperthermia or muscle rigor. Intraperitoneal bolus dantrolene before HAL prolongs time to respiratory arrest. A pilot electrographic study using subcutaneous electrodes reveals that dietary CAF does not alter baseline electroencephalogram (EEG) total power, but significantly shortens delay to isoelectric EEG, which precedes respiratory and cardiac arrest. CAF ± HAL are studied on RYR1 single-channel currents and HET myotubes to define molecular mechanisms of gene-by-environment synergism. Strong pharmacological synergism between CAF and HAL is demonstrated in both single-channel and myotube preparations. Central and peripheral nervous systems mediate adverse responses to HAL in a HET model of MH susceptibility exposed to dietary CAF, a modifiable lifestyle factor that may mitigate risks of acute and chronic diseases associated with RYR1 mutations. SIGNIFICANCE STATEMENT: Dietary caffeine at a human-relevant dose synergizes adverse peripheral and central responses to anesthesia in malignant hyperthermia susceptible mice. Synergism of these drugs can be attributed to their actions at ryanodine receptors.
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Affiliation(s)
- Monica Aleman
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Rui Zhang
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Wei Feng
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Lihong Qi
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Jose R Lopez
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Chelsea Crowe
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Yao Dong
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Genady Cherednichenko
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
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Lawal TA, Wires ES, Terry NL, Dowling JJ, Todd JJ. Preclinical model systems of ryanodine receptor 1-related myopathies and malignant hyperthermia: a comprehensive scoping review of works published 1990-2019. Orphanet J Rare Dis 2020; 15:113. [PMID: 32381029 PMCID: PMC7204063 DOI: 10.1186/s13023-020-01384-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/14/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Pathogenic variations in the gene encoding the skeletal muscle ryanodine receptor (RyR1) are associated with malignant hyperthermia (MH) susceptibility, a life-threatening hypermetabolic condition and RYR1-related myopathies (RYR1-RM), a spectrum of rare neuromuscular disorders. In RYR1-RM, intracellular calcium dysregulation, post-translational modifications, and decreased protein expression lead to a heterogenous clinical presentation including proximal muscle weakness, contractures, scoliosis, respiratory insufficiency, and ophthalmoplegia. Preclinical model systems of RYR1-RM and MH have been developed to better understand underlying pathomechanisms and test potential therapeutics. METHODS We conducted a comprehensive scoping review of scientific literature pertaining to RYR1-RM and MH preclinical model systems in accordance with the PRISMA Scoping Reviews Checklist and the framework proposed by Arksey and O'Malley. Two major electronic databases (PubMed and EMBASE) were searched without language restriction for articles and abstracts published between January 1, 1990 and July 3, 2019. RESULTS Our search yielded 5049 publications from which 262 were included in this review. A majority of variants tested in RYR1 preclinical models were localized to established MH/central core disease (MH/CCD) hot spots. A total of 250 unique RYR1 variations were reported in human/rodent/porcine models with 95% being missense substitutions. The most frequently reported RYR1 variant was R614C/R615C (human/porcine total n = 39), followed by Y523S/Y524S (rabbit/mouse total n = 30), I4898T/I4897T/I4895T (human/rabbit/mouse total n = 20), and R163C/R165C (human/mouse total n = 18). The dyspedic mouse was utilized by 47% of publications in the rodent category and its RyR1-null (1B5) myotubes were transfected in 23% of publications in the cellular model category. In studies of transfected HEK-293 cells, 57% of RYR1 variations affected the RyR1 channel and activation core domain. A total of 15 RYR1 mutant mouse strains were identified of which ten were heterozygous, three were compound heterozygous, and a further two were knockout. Porcine, avian, zebrafish, C. elegans, canine, equine, and drosophila model systems were also reported. CONCLUSIONS Over the past 30 years, there were 262 publications on MH and RYR1-RM preclinical model systems featuring more than 200 unique RYR1 variations tested in a broad range of species. Findings from these studies have set the foundation for therapeutic development for MH and RYR1-RM.
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Affiliation(s)
- Tokunbor A Lawal
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Emily S Wires
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Nancy L Terry
- National Institutes of Health Library, National Institutes of Health, Bethesda, MD, USA
| | - James J Dowling
- Program for Genetics and Genome Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Joshua J Todd
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, 20892, USA.
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Klocke C, Lein PJ. Evidence Implicating Non-Dioxin-Like Congeners as the Key Mediators of Polychlorinated Biphenyl (PCB) Developmental Neurotoxicity. Int J Mol Sci 2020; 21:E1013. [PMID: 32033061 PMCID: PMC7037228 DOI: 10.3390/ijms21031013] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 01/31/2020] [Accepted: 02/02/2020] [Indexed: 12/15/2022] Open
Abstract
Despite being banned from production for decades, polychlorinated biphenyls (PCBs) continue to pose a significant risk to human health. This is due to not only the continued release of legacy PCBs from PCB-containing equipment and materials manufactured prior to the ban on PCB production, but also the inadvertent production of PCBs as byproducts of contemporary pigment and dye production. Evidence from human and animal studies clearly identifies developmental neurotoxicity as a primary endpoint of concern associated with PCB exposures. However, the relative role(s) of specific PCB congeners in mediating the adverse effects of PCBs on the developing nervous system, and the mechanism(s) by which PCBs disrupt typical neurodevelopment remain outstanding questions. New questions are also emerging regarding the potential developmental neurotoxicity of lower chlorinated PCBs that were not present in the legacy commercial PCB mixtures, but constitute a significant proportion of contemporary human PCB exposures. Here, we review behavioral and mechanistic data obtained from experimental models as well as recent epidemiological studies that suggest the non-dioxin-like (NDL) PCBs are primarily responsible for the developmental neurotoxicity associated with PCBs. We also discuss emerging data demonstrating the potential for non-legacy, lower chlorinated PCBs to cause adverse neurodevelopmental outcomes. Molecular targets, the relevance of PCB interactions with these targets to neurodevelopmental disorders, and critical data gaps are addressed as well.
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Affiliation(s)
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA;
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15
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Tang NH, Kim KW, Xu S, Blazie SM, Yee BA, Yeo GW, Jin Y, Chisholm AD. The mRNA Decay Factor CAR-1/LSM14 Regulates Axon Regeneration via Mitochondrial Calcium Dynamics. Curr Biol 2020; 30:865-876.e7. [PMID: 31983639 DOI: 10.1016/j.cub.2019.12.061] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/26/2019] [Accepted: 12/19/2019] [Indexed: 12/11/2022]
Abstract
mRNA decay factors regulate mRNA turnover by recruiting non-translating mRNAs and targeting them for translational repression and mRNA degradation. How mRNA decay pathways regulate cellular function in vivo with specificity is poorly understood. Here, we show that C. elegans mRNA decay factors, including the translational repressors CAR-1/LSM14 and CGH-1/DDX6, and the decapping enzymes DCAP-1/DCP1, function in neurons to differentially regulate axon development, maintenance, and regrowth following injury. In neuronal cell bodies, CAR-1 fully colocalizes with CGH-1 and partially colocalizes with DCAP-1, suggesting that mRNA decay components form at least two types of cytoplasmic granules. Following axon injury in adult neurons, loss of CAR-1 or CGH-1 results in increased axon regrowth and growth cone formation, whereas loss of DCAP-1 or DCAP-2 results in reduced regrowth. To determine how CAR-1 inhibits regrowth, we analyzed mRNAs bound to pan-neuronally expressed GFP::CAR-1 using a crosslinking and immunoprecipitation-based approach. Among the putative mRNA targets of CAR-1, we characterized the roles of micu-1, a regulator of the mitochondrial calcium uniporter MCU-1, in axon injury. We show that loss of car-1 results increased MICU-1 protein levels, and that enhanced axon regrowth in car-1 mutants is dependent on micu-1 and mcu-1. Moreover, axon injury induces transient calcium influx into axonal mitochondria, dependent on MCU-1. In car-1 loss-of-function mutants and in micu-1 overexpressing animals, the axonal mitochondrial calcium influx is more sustained, which likely underlies enhanced axon regrowth. Our data uncover a novel pathway that controls axon regrowth through axonal mitochondrial calcium uptake.
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Affiliation(s)
- Ngang Heok Tang
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kyung Won Kim
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Suhong Xu
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Stephen M Blazie
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Brian A Yee
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Andrew D Chisholm
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
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Rude KM, Pusceddu MM, Keogh CE, Sladek JA, Rabasa G, Miller EN, Sethi S, Keil KP, Pessah IN, Lein PJ, Gareau MG. Developmental exposure to polychlorinated biphenyls (PCBs) in the maternal diet causes host-microbe defects in weanling offspring mice. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 253:708-721. [PMID: 31336350 PMCID: PMC6719698 DOI: 10.1016/j.envpol.2019.07.066] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/12/2019] [Accepted: 07/12/2019] [Indexed: 05/05/2023]
Abstract
The gut microbiota is important for maintaining homeostasis of the host. Gut microbes represent the initial site for toxicant processing following dietary exposures to environmental contaminants. The diet is the primary route of exposure to polychlorinated biphenyls (PCBs), which are absorbed via the gut, and subsequently interfere with neurodevelopment and behavior. Developmental exposures to PCBs have been linked to increased risk of neurodevelopmental disorders (NDD), including autism spectrum disorder (ASD), which are also associated with a high prevalence of gastrointestinal (GI) distress and intestinal dysbiosis. We hypothesized that developmental PCB exposure impacts colonization of the gut microbiota, resulting in GI pathophysiology, in a genetically susceptible host. Mouse dams expressing two heritable human mutations (double mutants [DM]) that result in abnormal Ca2+ dynamics and produce behavioral deficits (gain of function mutation in the ryanodine receptor 1 [T4826I-RYR1] and a human CGG repeat expansion [170-200 CGG repeats] in the fragile X mental retardation gene 1 [FMR1 premutation]). DM and congenic wild type (WT) controls were exposed to PCBs (0-6 mg/kg/d) in the diet starting 2 weeks before gestation and continuing through postnatal day 21 (P21). Intestinal physiology (Ussing chambers), inflammation (qPCR) and gut microbiome (16S sequencing) studies were performed in offspring mice (P28-P30). Developmental exposure to PCBs in the maternal diet caused significant mucosal barrier defects in ileum and colon (increased secretory state and tight junction permeability) of juvenile DM mice. Furthermore, PCB exposure increased the intestinal inflammatory profile (Il6, Il1β, and Il22), and resulted in dysbiosis of the gut microbiota, including altered β-diversity, in juvenile DM mice developmentally exposed to 1 mg/kg/d PCBs when compared to WT controls. Collectively, these findings demonstrate a novel interaction between PCB exposure and the gut microbiota in a genetically susceptible host that provide novel insight into environmental risk factors for neurodevelopmental disorders.
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Affiliation(s)
- Kavi M Rude
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Matteo M Pusceddu
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Ciara E Keogh
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Jessica A Sladek
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Gonzalo Rabasa
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Elaine N Miller
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Sunjay Sethi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Kimberly P Keil
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States
| | - Mélanie G Gareau
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, 95616, United States.
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17
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Zheng J, Yu Y, Feng W, Li J, Liu J, Zhang C, Dong Y, Pessah IN, Cao Z. Influence of Nanomolar Deltamethrin on the Hallmarks of Primary Cultured Cortical Neuronal Network and the Role of Ryanodine Receptors. ENVIRONMENTAL HEALTH PERSPECTIVES 2019; 127:67003. [PMID: 31166131 PMCID: PMC6792378 DOI: 10.1289/ehp4583] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 05/19/2023]
Abstract
BACKGROUND The pyrethroid deltamethrin (DM) is broadly used for insect control. Although DM hyperexcites neuronal networks by delaying inactivation of axonal voltage-dependent [Formula: see text] channels, this mechanism is unlikely to mediate neurotoxicity at lower exposure levels during critical perinatal periods in mammals. OBJECTIVES We aimed to identify mechanisms by which acute and subchronic DM altered axonal and dendritic growth, patterns of synchronous [Formula: see text] oscillations (SCOs), and electrical spike activity (ESA) functions critical to neuronal network formation. METHODS Measurements of SCOs using [Formula: see text] imaging, ESA using microelectrode array (MEA) technology, and dendritic complexity using Sholl analysis were performed in primary murine cortical neurons from wild-type (WT) and/or ryanodine receptor 1 ([Formula: see text]) mice between 5 and 14 d in vitro (DIV). [Formula: see text] binding analysis and a single-channel voltage clamp were utilized to measure engagement of RyRs as a direct target of DM. RESULTS Neuronal networks responded to DM ([Formula: see text]) as early as 5 DIV, reducing SCO amplitude and depressing ESA and burst frequencies by 60-70%. DM ([Formula: see text]) enhanced axonal growth in a nonmonotonic manner. [Formula: see text] enhanced dendritic complexity. DM stabilized channel open states of RyR1, RyR2, and cortical preparations expressing all three isoforms. DM ([Formula: see text]) altered gating kinetics of RyR1 channels, increasing mean open time, decreasing mean closed time, and thereby enhancing overall open probability. SCO patterns from cortical networks expressing [Formula: see text] were more responsive to DM than WT. [Formula: see text] neurons showed inherently longer axonal lengths than WT neurons and maintained less length-promoting responses to nanomolar DM. CONCLUSIONS Our findings suggested that RyRs were sensitive molecular targets of DM with functional consequences likely relevant for mediating abnormal neuronal network connectivity in vitro. https://doi.org/10.1289/EHP4583.
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Affiliation(s)
- Jing Zheng
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Yiyi Yu
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Wei Feng
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Jing Li
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Ju Liu
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Chunlei Zhang
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Yao Dong
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Isaac N. Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Zhengyu Cao
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
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Truong KM, Pessah IN. Comparison of Chlorantraniliprole and Flubendiamide Activity Toward Wild-Type and Malignant Hyperthermia-Susceptible Ryanodine Receptors and Heat Stress Intolerance. Toxicol Sci 2019; 167:509-523. [PMID: 30329129 PMCID: PMC6358238 DOI: 10.1093/toxsci/kfy256] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chlorantraniliprole (CP) and flubendiamide (FD) are widely used in agriculture globally to control lepidopteran pests. Both insecticides target ryanodine receptors (RyRs) and promote Ca2+ leak from sarcoplasmic reticulum (SR) within insect skeletal muscle yet are purportedly devoid of activity toward mammalian RyR1 and muscle. RyRs are ion channels that regulate intracellular Ca2+ release from SR during physiological excitation-contraction coupling. Mutations in RYR1 genes confer malignant hyperthermia susceptibility (MHS), a potentially lethal pharmacogenetic disorder in humans and animals. Compared with vehicle control, CP (10 µM) triggers a 65-fold higher rate of Ca2+ efflux from Ca2+-loaded mammalian WT-RyR1 SR vesicles, whereas FD (10 µM) produces negligible influence on Ca2+ leak. We, therefore, compared whether CP or FD differentially influence patterns of high-affinity [3H]ryanodine ([3H]Ry) binding to RyR1 isolated from muscle SR membranes prepared from adult C57BL/6J mice expressing WT, homozygous C-terminal MHS mutation T4826I, or heterozygous N-terminal MHS mutation R163C. Basal [3H]Ry binding differed among genotypes with rank order T4826I ≫R163C∼WT, regardless of [Ca2+] in the assay medium. Both CP and FD (0.01-100 µM) elicited concentration-dependent increase in [3H]Ry binding, although CP showed greater efficacy regardless of genotype or [Ca2+]. Exposure to CP (500 mg/kg; p.o) failed to shift intolerance to heat stress (38°C) characteristic of R163C and T4826I MHS mice, nor cause lethality in WT mice. Although nM-µM of either diamide is capable of differentially altering WT and MHS RyR1 conformation in vitro, human RyR1 mutations within putative diamide N- and C-terminal interaction domains do not alter heat stress intolerance (HSI) in vivo.
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Affiliation(s)
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616-5270
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19
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Keil KP, Sethi S, Wilson MD, Silverman JL, Pessah IN, Lein PJ. Genetic mutations in Ca 2+ signaling alter dendrite morphology and social approach in juvenile mice. GENES, BRAIN, AND BEHAVIOR 2019; 18:e12526. [PMID: 30311737 PMCID: PMC6540090 DOI: 10.1111/gbb.12526] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/05/2018] [Accepted: 10/09/2018] [Indexed: 01/28/2023]
Abstract
Dendritic morphology is a critical determinant of neuronal connectivity, and calcium signaling plays a predominant role in shaping dendrites. Altered dendritic morphology and genetic mutations in calcium signaling are both associated with neurodevelopmental disorders (NDDs). In this study we tested the hypothesis that dendritic arborization and NDD-relevant behavioral phenotypes are altered by human mutations that modulate calcium-dependent signaling pathways implicated in NDDs. The dendritic morphology of pyramidal neurons in CA1 hippocampus and somatosensory cortex was quantified in Golgi-stained brain sections from juvenile mice of both sexes expressing either a human gain-of-function mutation in ryanodine receptor 1 (T4826I-RYR1), a human CGG repeat expansion (170-200 CGG repeats) in the fragile X mental retardation gene 1 (FMR1 premutation), both mutations (double mutation; DM), or wildtype mice. In hippocampal neurons, increased dendritic arborization was observed in male T4826I-RYR1 and, to a lesser extent, male FMR1 premutation neurons. Dendritic morphology of cortical neurons was altered in both sexes of FMR1 premutation and DM animals with the most pronounced differences seen in DM females. Genotype also impaired behavior, as assessed using the three-chambered social approach test. The most striking lack of sociability was observed in DM male and female mice. In conclusion, mutations that alter the fidelity of calcium signaling enhance dendritic arborization in a brain region- and sex-specific manner and impair social behavior in juvenile mice. The phenotypic outcomes of these mutations likely provide a susceptible biological substrate for additional environmental stressors that converge on calcium signaling to determine individual NDD risk.
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Affiliation(s)
- Kimberly P. Keil
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, California
| | - Sunjay Sethi
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, California
| | - Machelle D. Wilson
- Clinical and Translational Science Center, Department of Public Health Sciences, Division of Biostatistics, University of California-Davis, School of Medicine, Davis, California
| | - Jill L. Silverman
- Department of Psychiatry and Behavioral Sciences, University of California-Davis School of Medicine, Sacramento, California
- MIND Institute, University of California-Davis, School of Medicine, Sacramento, California
| | - Isaac N. Pessah
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, California
- MIND Institute, University of California-Davis, School of Medicine, Sacramento, California
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, California
- MIND Institute, University of California-Davis, School of Medicine, Sacramento, California
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Malignant hyperthermia, environmental heat stress, and intracellular calcium dysregulation in a mouse model expressing the p.G2435R variant of RYR1. Br J Anaesth 2018; 121:953-961. [PMID: 30236258 DOI: 10.1016/j.bja.2018.07.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/22/2018] [Accepted: 07/16/2018] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The human p.G2434R variant of the RYR1 gene is most frequently associated with malignant hyperthermia (MH) in the UK. We report the phenotype of a knock-in mouse that expresses the RYR1 variant p.G2435R, which is isogenetic with the human variant. METHODS We observed the general phenotype; determined the sensitivity of myotubes to caffeine-, KCl, and halothane-induced Ca2+ release; determined the in vivo response to halothane or increased ambient temperature; and determined the in vivo myoplasmic intracellular Ca2+ concentration in skeletal muscle before and during exposure to volatile anaesthetics. RESULTS RYR1 pG2435R/MH normal (MHS-Heterozygous[Het]) or RYR1 pG2435R/pG2435R (MHS-Homozygous[Hom]) mice were fully viable under typical rearing conditions, although some male MHS-Hom mice died spontaneously. The normalised half-maximal effective concentration (95% confidence interval) for intracellular Ca2+ release in myotubes in response to KCl [MH normal, MHN, 21.4 (19.8-23.1) mM; MHS-Het 16.2 (15.2-17.2) mM; MHS-Hom 11.2 (10.2-12.2) mM] and caffeine (MHN, 5.7 (5-6.3) mM; MHS-Het 4.5 (3.9-5.0) mM; MHS-Hom 1.77 (1.5-2.1) mM] exhibited a gene dose-dependent decrease, and there was a gene dose-dependent increase in halothane sensitivity. Intact animals show a gene dose-dependent susceptibility to MH with volatile anaesthetics or to heat stroke. RYR1 p.G2435R mice had elevated skeletal muscle intracellular resting [Ca2+]i, (values are expressed as mean (SD)) (MHN 123 (3) nM; MHS-Het 156 (16) nM; MHS-Hom 265 (32) nM; P<0.001) and [Na+]i (MHN 8 (0.1) mM; MHS-Het 10 (1) mM; MHS-Hom 14 (0.7) mM; P<0.001) that was further increased by exposure to volatile anaesthetics. CONCLUSIONS RYR1 pG2435R mice demonstrated gene dose-dependent in vitro and in vivo responses to pharmacological and environmental stressors that parallel those seen in patients with the human RYR1 variant p.G2434R.
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Perez CF, Eltit JM, Lopez JR, Bodnár D, Dulhunty AF, Aditya S, Casarotto MG. Functional and structural characterization of a novel malignant hyperthermia-susceptible variant of DHPR-β 1a subunit (CACNB1). Am J Physiol Cell Physiol 2017; 314:C323-C333. [PMID: 29212769 DOI: 10.1152/ajpcell.00187.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Malignant hyperthermia (MH) susceptibility has been recently linked to a novel variant of β1a subunit of the dihydropyridine receptor (DHPR), a channel essential for Ca2+ regulation in skeletal muscle. Here we evaluate the effect of the mutant variant V156A on the structure/function of DHPR β1a subunit and assess its role on Ca2+ metabolism of cultured myotubes. Using differential scanning fluorimetry, we show that mutation V156A causes a significant reduction in thermal stability of the Src homology 3/guanylate kinase core domain of β1a subunit. Expression of the variant subunit in β1-null mouse myotubes resulted in increased sensitivity to caffeine stimulation. Whole cell patch-clamp analysis of β1a-V156A-expressing myotubes revealed a -2 mV shift in voltage dependence of channel activation, but no changes in Ca2+ conductance, current kinetics, or sarcoplasmic reticulum Ca2+ load were observed. Measurement of resting free Ca2+ and Na+ concentrations shows that both cations were significantly elevated in β1a-V156A-expressing myotubes and that these changes were linked to increased rates of plasmalemmal Ca2+ entry through Na+/Ca2+ exchanger and/or transient receptor potential canonical channels. Overall, our data show that mutant variant V156A results in instability of protein subdomains of β1a subunit leading to a phenotype of Ca2+ dysregulation that partly resembles that of other MH-linked mutations of DHPR α1S subunit. These data prove that homozygous expression of variant β1a-V156A has the potential to be a pathological variant, although it may require other gene defects to cause a full MH phenotype.
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Affiliation(s)
- Claudio F Perez
- Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University , Richmond, Virginia
| | - Jose R Lopez
- Department of Molecular Biosciences, University of California , Davis, California
| | - Dóra Bodnár
- Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Angela F Dulhunty
- John Curtin School of Medical Research, Australian National University , Canberra , Australia
| | - Shouvik Aditya
- John Curtin School of Medical Research, Australian National University , Canberra , Australia
| | - Marco G Casarotto
- John Curtin School of Medical Research, Australian National University , Canberra , Australia
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Gomez AC, Holford TW, Yamaguchi N. Malignant hyperthermia-associated mutations in the S2-S3 cytoplasmic loop of type 1 ryanodine receptor calcium channel impair calcium-dependent inactivation. Am J Physiol Cell Physiol 2016; 311:C749-C757. [PMID: 27558158 DOI: 10.1152/ajpcell.00134.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/19/2016] [Indexed: 11/22/2022]
Abstract
Channel activities of skeletal muscle ryanodine receptor (RyR1) are activated by micromolar Ca2+ and inactivated by higher (∼1 mM) Ca2+ To gain insight into a mechanism underlying Ca2+-dependent inactivation of RyR1 and its relationship with skeletal muscle diseases, we constructed nine recombinant RyR1 mutants carrying malignant hyperthermia or centronuclear myopathy-associated mutations and determined RyR1 channel activities by [3H]ryanodine binding assay. These mutations are localized in or near the RyR1 domains which are responsible for Ca2+-dependent inactivation of RyR1. Four RyR1 mutations (F4732D, G4733E, R4736W, and R4736Q) in the cytoplasmic loop between the S2 and S3 transmembrane segments (S2-S3 loop) greatly reduced Ca2+-dependent channel inactivation. Activities of these mutant channels were suppressed at 10-100 μM Ca2+, and the suppressions were relieved by 1 mM Mg2+ The Ca2+- and Mg2+-dependent regulation of S2-S3 loop RyR1 mutants are similar to those of the cardiac isoform of RyR (RyR2) rather than wild-type RyR1. Two mutations (T4825I and H4832Y) in the S4-S5 cytoplasmic loop increased Ca2+ affinities for channel activation and decreased Ca2+ affinities for inactivation, but impairment of Ca2+-dependent inactivation was not as prominent as those of S2-S3 loop mutants. Three mutations (T4082M, S4113L, and N4120Y) in the EF-hand domain showed essentially the same Ca2+-dependent channel regulation as that of wild-type RyR1. The results suggest that nine RyR1 mutants associated with skeletal muscle diseases were differently regulated by Ca2+ and Mg2+ Four malignant hyperthermia-associated RyR1 mutations in the S2-S3 loop conferred RyR2-type Ca2+- and Mg2+-dependent channel regulation.
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Affiliation(s)
- Angela C Gomez
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina; and.,Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
| | - Timothy W Holford
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina; and.,Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
| | - Naohiro Yamaguchi
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina; and .,Cardiac Signaling Center of University of South Carolina, Medical University of South Carolina, and Clemson University, Charleston, South Carolina
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23
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Rosenberg H, Pollock N, Schiemann A, Bulger T, Stowell K. Malignant hyperthermia: a review. Orphanet J Rare Dis 2015; 10:93. [PMID: 26238698 PMCID: PMC4524368 DOI: 10.1186/s13023-015-0310-1] [Citation(s) in RCA: 296] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 07/22/2015] [Indexed: 02/06/2023] Open
Abstract
Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle that presents as a hypermetabolic response to potent volatile anesthetic gases such as halothane, sevoflurane, desflurane, isoflurane and the depolarizing muscle relaxant succinylcholine, and rarely, in humans, to stressors such as vigorous exercise and heat. The incidence of MH reactions ranges from 1:10,000 to 1: 250,000 anesthetics. However, the prevalence of the genetic abnormalities may be as great as one in 400 individuals. MH affects humans, certain pig breeds, dogs and horses. The classic signs of MH include hyperthermia, tachycardia, tachypnea, increased carbon dioxide production, increased oxygen consumption, acidosis, hyperkalaemia, muscle rigidity, and rhabdomyolysis, all related to a hypermetabolic response. The syndrome is likely to be fatal if untreated. An increase in end-tidal carbon dioxide despite increased minute ventilation provides an early diagnostic clue. In humans the syndrome is inherited in an autosomal dominant pattern, while in pigs it is autosomal recessive. Uncontrolled rise of myoplasmic calcium, which activates biochemical processes related to muscle activation leads to the pathophysiologic changes. In most cases, the syndrome is caused by a defect in the ryanodine receptor. Over 400 variants have been identified in the RYR1 gene located on chromosome 19q13.1, and at least 34 are causal for MH. Less than 1 % of variants have been found in CACNA1S but not all of these are causal. Diagnostic testing involves the in vitro contracture response of biopsied muscle to halothane, caffeine, and in some centres ryanodine and 4-chloro-m-cresol. Elucidation of the genetic changes has led to the introduction of DNA testing for susceptibility to MH. Dantrolene sodium is a specific antagonist and should be available wherever general anesthesia is administered. Increased understanding of the clinical manifestation and pathophysiology of the syndrome, has lead to the mortality decreasing from 80 % thirty years ago to <5 % in 2006.
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Affiliation(s)
- Henry Rosenberg
- Department of Medical Education and Clinical Research, Saint Barnabas Medical Center, Livingston, NJ, 07039, USA.
| | - Neil Pollock
- Department of Anesthesia and Intensive Care, Palmerston North Hospital, Palmerston North, New Zealand.
| | - Anja Schiemann
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
| | - Terasa Bulger
- Department of Anesthesia and Intensive Care, Palmerston North Hospital, Palmerston North, New Zealand.
| | - Kathryn Stowell
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand.
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The disorders of the calcium release unit of skeletal muscles: what have we learned from mouse models? J Muscle Res Cell Motil 2014; 36:61-9. [PMID: 25424378 DOI: 10.1007/s10974-014-9396-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 10/29/2014] [Indexed: 01/01/2023]
Abstract
Calcium storage, release, and reuptake are essential for normal physiological function of muscle. Several human skeletal muscle disorders can arise from dysfunction in the control and coordination of these three critical processes. The release from the Sarcoplasmic Reticulum stores (SR) is handled by a multiprotein complex called Calcium Release Unit and composed of DiHydroPyridine Receptor or DHPR, Ryanodine Receptor or RYR, Calsequestrin or CASQ, junctin, Triadin, Junctophilin and Mitsugumin 29. Malignant hyperthermia (MH), Central Core Disease (CCD), Exertional/environmental Heat Stroke (EHS) and Multiminicore disease (MmD) are inherited disorders of calcium homeostasis in skeletal muscles directly related to mutations of genes coding for proteins of the CRU, primarily ryanodine receptor (RYR1). To understand the pathophysiology of MH and CCD, four murine lines carrying point mutations of human RYR1 have been developed: Y524S, R163C, I4898T and T4826I. Mice carrying those mutations show a phenotype with the traits of MH and/or CCD. Interestingly, also ablation of skeletal muscle calsequestrin (CASQ1) leads to a phenotype with MH-like lethal episodes in response to halothane and heat stress and development of central cores. In this review, we aim to describe the murine lines with RYR mutations or CASQ ablation, which show a phenotype similar to human MH or CCD, to underline their specific phenotypes and their differences and to discuss their contribution to the understanding of the pathophysiology of the disorders and the development of therapeutic strategies.
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Myoplasmic resting Ca2+ regulation by ryanodine receptors is under the control of a novel Ca2+-binding region of the receptor. Biochem J 2014; 460:261-71. [PMID: 24635445 PMCID: PMC4019983 DOI: 10.1042/bj20131553] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Passive SR (sarcoplasmic reticulum) Ca2+ leak through the RyR (ryanodine receptor) plays a critical role in the mechanisms that regulate [Ca2+]rest (intracellular resting myoplasmic free Ca2+ concentration) in muscle. This process appears to be isoform-specific as expression of either RyR1 or RyR3 confers on myotubes different [Ca2+]rest. Using chimaeric RyR3–RyR1 receptors expressed in dyspedic myotubes, we show that isoform-dependent regulation of [Ca2+]rest is primarily defined by a small region of the receptor encompassing amino acids 3770–4007 of RyR1 (amino acids 3620–3859 of RyR3) named as the CLR (Ca2+ leak regulatory) region. [Ca2+]rest regulation by the CLR region was associated with alteration of RyRs’ Ca2+-activation profile and changes in SR Ca2+-leak rates. Biochemical analysis using Tb3+-binding assays and intrinsic tryptophan fluorescence spectroscopy of purified CLR domains revealed that this determinant of RyRs holds a novel Ca2+-binding domain with conformational properties that are distinctive to each isoform. Our data suggest that the CLR region provides channels with unique functional properties that modulate the rate of passive SR Ca2+ leak and confer on RyR1 and RyR3 distinctive [Ca2+]rest regulatory properties. The identification of a new Ca2+-binding domain of RyRs with a key modulatory role in [Ca2+]rest regulation provides new insights into Ca2+-mediated regulation of RyRs. This paper reports the finding of a new class of Ca2+-binding domain of intracellular Ca2+ channels from muscle cells. This domain provides channels with distinctive properties that result in channel-specific modulation of the intracellular resting Ca2+ concentration.
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Abstract
The advent of the polymerase chain reaction and the availability of data from various global human genome projects should make it possible, using a DNA sample isolated from white blood cells, to diagnose rapidly and accurately almost any monogenic condition resulting from single nucleotide changes. DNA-based diagnosis for malignant hyperthermia (MH) is an attractive proposition, because it could replace the invasive and morbid caffeine-halothane/in vitro contracture tests of skeletal muscle biopsy tissue. Moreover, MH is preventable if an accurate diagnosis of susceptibility can be made before general anesthesia, the most common trigger of an MH episode. Diagnosis of MH using DNA was suggested as early as 1990 when the skeletal muscle ryanodine receptor gene (RYR1), and a single point mutation therein, was linked to MH susceptibility. In 1994, a single point mutation in the α 1 subunit of the dihydropyridine receptor gene (CACNA1S) was identified and also subsequently shown to be causative of MH. In the succeeding years, the number of identified mutations in RYR1 has grown, as has the number of potential susceptibility loci, although no other gene has yet been definitively associated with MH. In addition, it has become clear that MH is associated with either of these 2 genes (RYR1 and CACNA1S) in only 50% to 70% of affected families. While DNA testing for MH susceptibility has now become widespread, it still does not replace the in vitro contracture tests. Whole exome sequence analysis makes it potentially possible to identify all variants within human coding regions, but the complexity of the genome, the heterogeneity of MH, the limitations of bioinformatic tools, and the lack of precise genotype/phenotype correlations are all confounding factors. In addition, the requirement for demonstration of causality, by in vitro functional analysis, of any familial mutation currently precludes DNA-based diagnosis as the sole test for MH susceptibility. Nevertheless, familial DNA testing for MH susceptibility is now widespread although limited to a positive diagnosis and to those few mutations that have been functionally characterized. Identification of new susceptibility genes remains elusive. When new genes are identified, it will be the role of the biochemists, physiologists, and biophysicists to devise functional assays in appropriate systems. This will remain the bottleneck unless high throughput platforms can be designed for functional work. Analysis of entire genomes from several individuals simultaneously is a reality. DNA testing for MH, based on current criteria, remains the dream.
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Affiliation(s)
- Kathryn M Stowell
- From the Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
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27
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Stamou M, Streifel KM, Goines PE, Lein PJ. Neuronal connectivity as a convergent target of gene × environment interactions that confer risk for Autism Spectrum Disorders. Neurotoxicol Teratol 2013; 36:3-16. [PMID: 23269408 PMCID: PMC3610799 DOI: 10.1016/j.ntt.2012.12.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 11/12/2012] [Accepted: 12/17/2012] [Indexed: 11/21/2022]
Abstract
Evidence implicates environmental factors in the pathogenesis of Autism Spectrum Disorders (ASD). However, the identity of specific environmental chemicals that influence ASD risk, severity or treatment outcome remains elusive. The impact of any given environmental exposure likely varies across a population according to individual genetic substrates, and this increases the difficulty of identifying clear associations between exposure and ASD diagnoses. Heritable genetic vulnerabilities may amplify adverse effects triggered by environmental exposures if genetic and environmental factors converge to dysregulate the same signaling systems at critical times of development. Thus, one strategy for identifying environmental risk factors for ASD is to screen for environmental factors that modulate the same signaling pathways as ASD susceptibility genes. Recent advances in defining the molecular and cellular pathology of ASD point to altered patterns of neuronal connectivity in the developing brain as the neurobiological basis of these disorders. Studies of syndromic ASD and rare highly penetrant mutations or CNVs in ASD suggest that ASD risk genes converge on several major signaling pathways linked to altered neuronal connectivity in the developing brain. This review briefly summarizes the evidence implicating dysfunctional signaling via Ca(2+)-dependent mechanisms, extracellular signal-regulated kinases (ERK)/phosphatidylinositol-3-kinases (PI3K) and neuroligin-neurexin-SHANK as convergent molecular mechanisms in ASD, and then discusses examples of environmental chemicals for which there is emerging evidence of their potential to interfere with normal neuronal connectivity via perturbation of these signaling pathways.
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Affiliation(s)
- Marianna Stamou
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Karin M. Streifel
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Paula E. Goines
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
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28
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Eltit JM, Ding X, Pessah IN, Allen PD, Lopez JR. Nonspecific sarcolemmal cation channels are critical for the pathogenesis of malignant hyperthermia. FASEB J 2012; 27:991-1000. [PMID: 23159934 DOI: 10.1096/fj.12-218354] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Malignant hyperthermia (MH) susceptibility has been attributed to a leaky sarcoplasmic reticulum (SR) caused by missense mutations in RYR1 or CACNA1S, and the MH crisis has been attributed solely to massive self-sustaining release of Ca(2+) from SR stores elicited by triggering agents. Here, we show in muscle cells from MH-RyR1(R163C) knock-in mice that increased passive SR Ca(2+) leak causes an enlarged basal influx of sarcolemmal Ca(2+) that results in chronically elevated myoplasmic free Ca(2+) concentration ([Ca(2+)]i) at rest. We discovered that Gd(+3) and GsMTx-4 were more effective than BTP2 or expression of the dominant-negative Orai1(E190Q) in reducing both Ca(2+) entry and [Ca(2+)]i, implicating a non-STIM1/Orai1 SOCE pathway in resetting resting [Ca(2+)]i. Indeed, two nonselective cationic channels, TRPC3 and TRPC6, are overexpressed, and [Na]i is chronically elevated in MH-RyR1(R163C) muscle cells. [Ca(2+)]i and [Na(+)]i are persistently elevated in vivo and further increased by halothane in MH-RyR1(R163C/WT) muscle. These increases are markedly attenuated by local perfusion of Gd(+3) or GsMTx-4 and completely suppressed by dantrolene. These results contribute a new paradigm for understanding MH pathophysiology by demonstrating that nonselective sarcolemmal cation channel activity plays a critical role in causing myoplasmic Ca(2+) and Na(+) overload both at rest and during the MH crisis.-Eltit, J. M., Ding, X., Pessah, I. N., Allen, P. D., Lopez, J. R. Nonspecific sarcolemmal cation channels are critical for the pathogenesis of malignant hyperthermia.
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Affiliation(s)
- José M Eltit
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia, USA
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29
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Wayman GA, Yang D, Bose DD, Lesiak A, Ledoux V, Bruun D, Pessah IN, Lein PJ. PCB-95 promotes dendritic growth via ryanodine receptor-dependent mechanisms. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:997-1002. [PMID: 22534141 PMCID: PMC3404670 DOI: 10.1289/ehp.1104832] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 04/02/2012] [Indexed: 05/18/2023]
Abstract
BACKGROUND Aroclor 1254 (A1254) interferes with normal dendritic growth and plasticity in the developing rodent brain, but the mechanism(s) mediating this effect have yet to be established. Non-dioxin-like (NDL) polychlorinated biphenyls (PCBs) enhance the activity of ryanodine receptor (RyR) calcium ion (Ca(2+)) channels, which play a central role in regulating the spatiotemporal dynamics of intracellular Ca(2+) signaling. Ca(2+) signaling is a predominant factor in shaping dendritic arbors, but whether PCB potentiation of RyR activity influences dendritic growth is not known. OBJECTIVE We determined whether RyR activity is required for PCB effects on dendritic growth. METHODS AND RESULTS Golgi analysis of hippocampi from weanling rats confirmed that developmental exposure via the maternal diet to NDL PCB-95 (2,2',3,5'6-pentachlorobiphenyl), a potent RyR potentiator, phenocopies the dendrite-promoting effects of A1254. Dendritic growth in dissociated cultures of primary hippocampal neurons and in hippocampal slice cultures is similarly enhanced by PCB-95 but not by PCB-66 (2,3,4',4-tetrachlorobiphenyl), a congener with negligible effects on RyR activity. The dendrite-promoting effects of PCB-95 are evident at concentrations as low as 2 pM and are inhibited by either pharmacologic blockade or siRNA knockdown of RyRs. CONCLUSIONS Our findings demonstrate that environmentally relevant levels of NDL PCBs modulate neuronal connectivity via RyR-dependent effects on dendritic arborization. In addition, these findings identify RyR channel dysregulation as a novel mechanism contributing to dysmorphic dendritogenesis associated with heritable and environmentally triggered neurodevelopmental disorders.
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Affiliation(s)
- Gary A Wayman
- Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington, USA
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