Alterations in T-tubule and dyad structure in heart disease: challenges and opportunities for computational analyses

Poláková, Eva; Sobie, Eric A.

doi:10.1093/cvr/cvt026

Cited by 20 publications

(17 citation statements)

References 77 publications

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“…11 Activation and gating of RyRs is dependent on local [Ca 2+ ], cytosolic and luminal, 12 and is further modulated through modification such as oxidation, nitrosylation, and phosphorylation. [13][14][15] Many proteins are involved; both kinases and phosphatases associate with the RyRs to form a macrocomplex.…”

mentioning

confidence: 99%

Selective Modulation of Coupled Ryanodine Receptors During Microdomain Activation of Calcium/Calmodulin-Dependent Kinase II in the Dyadic Cleft

Dries

Bito

Lenaerts

et al. 2013

Circulation Research

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mentioning

confidence: 99%

Selective Modulation of Coupled Ryanodine Receptors During Microdomain Activation of Calcium/Calmodulin-Dependent Kinase II in the Dyadic Cleft

Dries

Bito

Lenaerts

et al. 2013

Circulation Research

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“…In addition, the structural continuity in the oblique configuration opens the possibility of a higher degree of synchronization, either by virtue of holding two RyR2s together and facilitating CICR or by allosteric coupling. It has been suggested that the substructure of the CRU may be an important determinant of the kinetics of the Ca 2þ spark (14,15). Our work shows several possible RyR2 quaternary interactions within the CRU that could constitute a mechanism to fine-tune the SR Ca 2þ release kinetics during EC coupling.…”

Section: Physiological Implicationsmentioning

confidence: 99%

“…Walker et al (14) simulated the fine geometrical details of a CRU based on superresolution microscopy data and found that densely packed RyR2 arrays have the highest Ca 2þ spark fidelity. A more accurate structural detail of RyR2 clustering is necessary not only to model the canonical Ca 2þ spark as realistically as possible, but to make predictive models (15) that can accurately correlate alterations in specific parameters such as RyR2 cluster size, connectedness, and local SR volume (16) with the macroscopic defective Ca 2þ release observed in arrhythmia and heart failure.…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural Analysis of Self-Associated RyR2s

Cabra

Murayama

Samsó

2016

Biophysical Journal

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In heart, type-2 ryanodine receptor (RyR2) forms discrete supramolecular clusters in the sarcoplasmic reticulum known as calcium release units (CRUs), which are responsible for most of the Ca(2+) released for muscle contraction. To learn about the substructure of the CRU, we sought to determine whether RyR2s have the ability to self-associate in the absence of other factors and if so, whether they do it in a specific manner. Purified RyR2 was negatively stained and imaged on the transmission electron microscope, and RyR2 particles closely associated were further analyzed using bias-free multivariate statistical analysis and classification. The resulting two-dimensional averages show that RyR2s can interact in two rigid, reproducible configurations: "adjoining", with two RyR2s alongside each other, and "oblique", with two partially overlapped RyR2s forming an angle of 12°. The two configurations are nearly identical under two extreme physiological Ca(2+) concentrations. Pseudo-atomic models for these two interactions indicate that the adjoining interaction involves contacts between the P1, SPRY1 and the helical domains. The oblique interaction is mediated by extensive contacts between the SPRY1 domains (domains 9) and P1 domains (domains 10) of both RyR2s and not through domain 6 as previously thought; in addition its asymmetric interface imposes steric constrains that inhibit the growth of RyR2 as a checkerboard, which is the configuration usually assumed, and generates new configurations, i.e., "branched" and "interlocked". This first, to our knowledge, structural detailed analysis of the inter-RyR2 interactions helps to understand important morphological and functional aspects of the CRU in the context of cardiac EC coupling.

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“…However, JPH2 depletion in this mouse model also causes severe cardiomyopathy and heart failure 2,8 . T-tubule disruption is present in hearts with cardiomyopathy and heart failure 9–10 . Thus cardiomyopathy and heart failure confound the interpretation of the Jph2 knockdown phenotype with regard to its role in T-tubule maturation.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Cardiac Myocyte Maturation Using CASAAV, a Platform for Rapid Dissection of Cardiac Myocyte Gene Function In Vivo

Guo

VanDusen

Zhang

et al. 2017

Circulation Research

115

138

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Rationale Loss-of-function studies in cardiac myocytes (CMs) are currently limited by the need for appropriate conditional knockout alleles. The factors that regulate CM maturation are poorly understood. Prior studies on CM maturation have been confounded by heart dysfunction caused by whole organ gene inactivation. Objective To develop a new technical platform to rapidly characterize cell-autonomous gene function in postnatal murine CMs and apply it to identify genes that regulate T-tubules, a hallmark of mature cardiac myocytes. Methods and Results We developed CASAAV (CRISPR/Cas9-AAV9-based somatic mutagenesis), a platform in which AAV9 delivers tandem guide RNAs targeting a gene of interest and cardiac troponin T promoter (cTNT)-driven Cre to RosaCas9GFP/Cas9GFP neonatal mice. When directed against junctophilin-2 (Jph2), a gene previously implicated in T-tubule maturation, we achieved efficient, rapid, and CM-specific JPH2 depletion. High-dose AAV9 ablated JPH2 in 64% CMs and caused lethal heart failure, whereas low-dose AAV9 ablated JPH2 in 22% CMs and preserved normal heart function. In the context of preserved heart function, CMs lacking JPH2 developed T-tubules that were nearly morphologically normal, indicating that JPH2 does not have a major, cell-autonomous role in T-tubule maturation. However, in hearts with severe dysfunction, both AAV-transduced and non-transduced CMs exhibited T-tubule disruption, which was more severe in the transduced subset. These data indicate that cardiac dysfunction disrupts T-tubule structure, and that JPH2 protects T-tubules in this context. We then used CASAAV to screen 8 additional genes for required, cell-autonomous roles in T-tubule formation. We identified ryanodine receptor 2 (RYR2) as a novel, cell-autonomously required T-tubule maturation factor. Conclusions CASAAV is a powerful tool to study cell-autonomous gene functions. Genetic mosaics are invaluable to accurately define cell-autonomous gene function. JPH2 has a minor role in normal T-tubule maturation but is required to stabilize T-tubules in the failing heart. RYR2 is a novel T-tubule maturation factor.

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Alterations in T-tubule and dyad structure in heart disease: challenges and opportunities for computational analyses

Cited by 20 publications

References 77 publications

Selective Modulation of Coupled Ryanodine Receptors During Microdomain Activation of Calcium/Calmodulin-Dependent Kinase II in the Dyadic Cleft

Selective Modulation of Coupled Ryanodine Receptors During Microdomain Activation of Calcium/Calmodulin-Dependent Kinase II in the Dyadic Cleft

Ultrastructural Analysis of Self-Associated RyR2s

Analysis of Cardiac Myocyte Maturation Using CASAAV, a Platform for Rapid Dissection of Cardiac Myocyte Gene Function In Vivo

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