Structural Insights Into Disease Mutations of the Ryanodine Receptor

Abstract

Ca 2+ ions form important intracellular messenger molecules in nearly every cell type of the human body. Under so-called "resting" states of the cell, the concentration of Ca 2+ in the cytoplasm is extremely low (~10-7 M), but this can rapidly rise ~2 orders of magnitude when an appropriate signal is generated. Ca 2+ ions can enter the cytoplasm either from the extracellular space or from intracellular compartments, through specialized membrane proteins. These "calcium channels" are complex proteins, often consisting of multiple subunits, and are targets for multiple regulatory events. A major intracellular Ca 2+ store is the endoplasmic reticulum (ER), or its specialized form, the sarcoplasmic reticulum (SR) in muscle tissue. The mobilization of Ca 2+ from these organelles can trigger many Ca 2+-dependent events, such as the contraction of muscle tissue. The coupling between electrical excitation of a muscle cell and its subsequent contraction (excitation-contraction coupling, E-C coupling) is a finely orchestrated process that requires a functional cross-talk between proteins embedded in the plasma membrane and in the SR membrane (Figure 1). An electrical signal, a depolarization of the plasma membrane, can lead to opening of Ltype voltage-gated calcium channels (Ca V), which results in the influx of Ca 2+ into the cytoplasm. In the SR membrane, large calcium release channels called Ryanodine Receptors (RyRs) can detect this initial influx, and release more Ca 2+ in a process known as Ca 2+-induced Ca 2+ release (CICR). The latter event provides the bulk of the Ca 2+ required for contraction to occur. In this scenario, the RyRs form signal amplifiers, which both detect and augment the Ca 2+ signal [1, 2]. This scenario likely predominates in cardiac tissue, but Ca 2+ is not always required to open RyRs. In skeletal muscle, for example, various pieces of evidence suggest a direct interaction between the L-type calcium channel (Ca V 1.1) and the RyR [3-6]. In this case, the depolari

Crystal structure of diamondback moth ryanodine receptor Repeat34 domain reveals insect-specific phosphorylation sites

“…Previously, it was reported that a single RyR1 mutation L2867G that causes malignant hyperthermia (MH) can reduce the Tm of RyR1 Repeat34 by 13 °C [44]. One common mechanism for MH or CPVT mutations is to affect the stability and cause misfolding of RyR domains, consequently causing the gain-of-function phenotype of the channel [58]. Thus, some non-conserved residues in DBM Repeat34 could cause the destabilization of the domain, which might contribute to the high activity of the channel [59].…”

Triclosan Affects Ca2+ Regulatory Module and Musculature Development in Skeletal Myocyte during Early Life Stages of Zebrafish (Danio rerio)

“…45 The RyR gating is stimulated by Ca 2+ -induced conformational changes in the core solenoid and C-terminal domain (CTD) which lead to the couple cytoplasmic shell (poly alanine-level models) movement to pore opening (atomic-level model). 46−48 In fish, the RyR1 genes (ryraa and ryrab) are the predominant genes expressed in the skeletal muscle, controlling the calcium release from intracellular stores, 49,50 and these interactions influence important aspects of the Ca 2+ channel function that either are essential for excitation−contraction coupling (ECC) or finetune the spatial and temporal spread of Ca 2+ signals in myocytes. 51 Several investigations also show that muscle damage and progression disorders are mediated by RyRs.…”

“…The composition of RyRs macromolecular complexes is therefore an important checkpoint that induces diverse actions of Ca 2+ signaling by noncoplanar TCS in tissues and cells. ,, However, the fundamental conclusions of structure and function of RyRs in health and disease are limited. Recently, because of advances in single-particle cryogenic electron microscopy (cryo-EM), Santulli et al were able to detect for the first time the atomic-level structures of RyR. The RyR gating is stimulated by Ca 2+ -induced conformational changes in the core solenoid and C-terminal domain (CTD) which lead to the couple cytoplasmic shell (poly alanine-level models) movement to pore opening (atomic-level model). − In fish, the RyR1 genes ( ryraa and ryrab ) are the predominant genes expressed in the skeletal muscle, controlling the calcium release from intracellular stores, , and these interactions influence important aspects of the Ca 2+ channel function that either are essential for excitation–contraction coupling (ECC) or fine-tune the spatial and temporal spread of Ca 2+ signals in myocytes . Several investigations also show that muscle damage and progression disorders are mediated by RyRs. − …”

Rapid screening for mutations associated with malignant hyperthermia using high-resolution melting curve analysis

“…While examining the hotspots located in the RYR1 3D protein folding map, it is interesting that all the hotspots are located at the inner face of the channel. The RyR1 channels with those hotspot mutations have significantly lowered threshold for activation by Ca 2+ and increased threshold for inactivation by Ca 2+ [ 13 ]. In this context, DHPLC is a useful and efficient method for mutation screening in a large number of sequences, with high sensitivity when used to identifying various inherited diseases [ 14 ].…”