Recent advances in understanding the ryanodine receptor calcium release channels and their role in calcium signalling

MDFI regulates fast-to-slow muscle fiber type transformation via the calcium signaling pathway

Muscle fiber is the basic unit of skeletal muscle with strong self-adaptability, and its type is closely related to meat quality. Myod family inhibitor (Mdfi) has the function of regulating myogenic regulatory factors during cell differentiation, but how Mdfi regulates muscle fiber type transformation in myoblasts is still unclear. In the present study, we constructed overexpressing and interfering with Mdfi C2C12 cell models by lipofection. The immunofluorescence, quantitative real-time PCR (qPCR), and western blot results show that the elevated MDFI promoted mitochondrial biogenesis, aerobic metabolism and the calcium level by activating CaMKK2 and AMPK phosphorylation and then stimulated the conversion of C2C12 cells from fast glycolytic to slow oxidative type. In addition, after inhibiting IP3R and RYR channels, the higher MDFI reversed the blockage of calcium release from the endoplasmic reticulum by calcium channel receptor inhibitors and increased intracellular calcium levels. Therefore, we propose that the higher MDFI promotes muscle fiber types conversion through the calcium signaling pathway. These findings further broaden our understanding of the regulatory mechanism of MDFI in muscle fiber type transformation. Furthermore, our results suggest potential therapeutic targets for skeletal muscle and metabolic-related diseases.

Development of Ryanodine Receptor (RyR) Inhibitors for Skeletal Muscle and Heart Diseases

Ryanodine receptors (RyR) are intracellular calcium (Ca2+) release channels on the sarcoplasmic reticulum of skeletal and cardiac muscles that play a central role in excitation-contraction coupling. Genetic mutations or posttranslational modifications of RyR causes hyperactivation of the channel, leading to various skeletal muscle and heart diseases. Currently, no specific treatments exist for most RyR-associated diseases. Recently, high-throughput screening (HTS) assays have been developed to identify potential candidates for treating RyR-related muscle diseases. These assays have successfully identified several compounds as novel RyR inhibitors, which are effective in animal models. In this review, we will focus on recent progress in HTS assays and discuss future perspectives of these promising approaches.

Drug development for the treatment of RyR1-related skeletal muscle diseases

Type 1 ryanodine receptor (RyR1) is an intracellular Ca²⁺ release channel on the sarcoplasmic reticulum of skeletal muscle, and it plays a central role in excitation-contraction (E-C) coupling. Mutations in RyR1 are implicated in various muscle diseases including malignant hyperthermia, central core disease, and myopathies. Currently, no specific treatment exists for most of these diseases. Recently, high-throughput screening (HTS) assays have been developed for identifying potential candidates for treating RyR-related muscle diseases. Currently, two different methods, namely a FRET-based assay and an endoplasmic reticulum Ca²⁺-based assay, are available. These assays identified several compounds as novel RyR1 inhibitors. In addition, the development of a reconstituted platform permitted HTS assays for E-C coupling modulators. In this review, we will focus on recent progress in HTS assays and discuss future perspectives of these promising approaches.

Functional Insights into Protein Kinase A (PKA) Signaling from C. elegans

Protein kinase A (PKA), which regulates a diverse set of biological functions downstream of cyclic AMP (cAMP), is a tetramer consisting of two catalytic subunits (PKA-C) and two regulatory subunits (PKA-R). When cAMP binds the PKA-R subunits, the PKA-C subunits are released and interact with downstream effectors. In Caenorhabditis elegans (C. elegans), PKA-C and PKA-R are encoded by kin-1 and kin-2, respectively. This review focuses on the contributions of work in C. elegans to our understanding of the many roles of PKA, including contractility and oocyte maturation in the reproductive system, lipid metabolism, physiology, mitochondrial function and lifespan, and a wide variety of behaviors. C. elegans provides a powerful genetic platform for understanding how this kinase can regulate an astounding variety of physiological responses.

Ventricular arrhythmias in acute myocardial ischaemia-Focus on the ageing and sex

Annually, approximately 17 million people die from cardiovascular diseases worldwide, half of them suddenly. The most common direct cause of sudden cardiac death is ventricular arrhythmia triggered by an acute coronary syndrome (ACS). The study summarizes the knowledge of the mechanisms of arrhythmia onset during ACS in humans and in animal models and factors that may influence the susceptibility to life-threatening arrhythmias during ACS with particular focus on the age and sex. The real impact of age and sex on the arrhythmic susceptibility within the setting of acute ischaemia is masked by the fact that ACSs result from coronary artery disease appearing with age much earlier among men than among women. However, results of researches show that in ageing process changes with potential pro-arrhythmic significance, such as increased fibrosis, cardiomyocyte hypertrophy, decrease number of gap junction channels, disturbances of the intracellular Ca²⁺ signalling or changes in electrophysiological parameters, occur independently of the development of cardiovascular diseases and are more severe in male individuals. A review of the literature also indicates a marked paucity of research in this area in female and elderly individuals. Greater awareness of sex differences in the aging process could help in the development of personalized prevention methods targeting potential pro-arrhythmic factors in patients of both sexes to reduce mortality during the acute phase of myocardial infarction. This is especially important in an era of aging populations in which women will predominate due to their longer lifespan.

Direct Ryanodine Receptor-2 Knockout in Primary Afferent Fibers Modestly Affects Neurological Recovery after Contusive Spinal Cord Injury

Neuronal ryanodine receptors (RyR) release calcium from internal stores and play a key role in synaptic plasticity, learning, and memory. Dysregulation of RyR function contributes to neurodegeneration and negatively impacts neurological recovery after spinal cord injury (SCI). However, the individual role of RyR isoforms and the underlying mechanisms remain poorly understood. To determine whether RyR2 plays a direct role in axonal fate and functional recovery after SCI, we bred Advillin-Cre: tdTomato (Ai9) reporter mice with "floxed" RyR2 mice to directly knock out (KO) RyR2 function in dorsal root ganglion neurons and their spinal projections. Adult 6- to 8-week-old RyR2KO and littermate controls were subjected to a contusive SCI and their dorsal column axons were imaged in vivo using two-photon excitation microscopy. We found that direct RyR2KO in dorsal column primary afferents did not significantly alter secondary axonal degeneration after SCI. We next assessed behavioral recovery after SCI and found that direct RyR2KO in primary afferents worsened open-field locomotor scores (Basso Mouse Scale subscore) compared to littermate controls. However, both TreadScan™ gait analysis and overground kinematic gait analysis tests revealed subtle, but no fundamental, differences in gait patterns between the two groups after SCI. Subsequent removal of spared afferent fibers using a dorsal column crush revealed similar outcomes in both groups. Analysis of primary afferents at the lumbar (L3-L5) level similarly revealed no noticeable differences between groups. Together, our results support a modest contribution of dorsal column primary afferent RyR2 in neurological recovery after SCI.

Electron microscopy of cardiac 3D nanodynamics: form, function, future

The 3D nanostructure of the heart, its dynamic deformation during cycles of contraction and relaxation, and the effects of this deformation on cell function remain largely uncharted territory. Over the past decade, the first inroads have been made towards 3D reconstruction of heart cells, with a native resolution of around 1 nm³, and of individual molecules relevant to heart function at a near-atomic scale. These advances have provided access to a new generation of data and have driven the development of increasingly smart, artificial intelligence-based, deep-learning image-analysis algorithms. By high-pressure freezing of cardiomyocytes with millisecond accuracy after initiation of an action potential, pseudodynamic snapshots of contraction-induced deformation of intracellular organelles can now be captured. In combination with functional studies, such as fluorescence imaging, exciting insights into cardiac autoregulatory processes at nano-to-micro scales are starting to emerge. In this Review, we discuss the progress in this fascinating new field to highlight the fundamental scientific insight that has emerged, based on technological breakthroughs in biological sample preparation, 3D imaging and data analysis; to illustrate the potential clinical relevance of understanding 3D cardiac nanodynamics; and to predict further progress that we can reasonably expect to see over the next 10 years.

Therapies for RYR1-Related Myopathies: Where We Stand and the Perspectives

RyR1-related myopathies are a family of genetic neuromuscular diseases due to mutations in the RYR1 gene. No treatment exists for any of these myopathies today, which could change in the coming years with the growing number of studies dedicated to the pre-clinical assessment of various approaches, from pharmacological to gene therapy strategies, using the numerous models developed up to now. In addition, the first clinical trials for these rare diseases have just been completed or are being launched. We review the most recent results obtained for the treatment of RyR1-related myopathies, and, in view of the progress in therapeutic development for other myopathies, we discuss the possible future therapeutic perspectives for RyR1-related myopathies.

The effect of iron on the expression levels of calcium related gene in cisplatin resistant epithelial ovarian cancer cells

Aim: Anticancer drugs (chemotherapeutics) used in cancer treatment (chemotherapy) lead to drug resistance. This study was conducted to investigate the possible effect of iron on calcium homeostasis in epithelial ovarian cancer cells (MDAH-2774) and cisplatin-resistant cells of the same cell line (MDAH-2774/DDP). Methods: To develop MDAH-2774/DDP cells, MDAH-2774 (MDAH) cells were treated with cisplatin in dose increases of 5 μM between 0 μM and 70 μM. The effect of iron on the viability of MDAH and MDAH/DDP cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test at the end of 24 h incubation. Results: At increasing iron concentrations in MDAH and MDAH/DDP cells, the mRNA gene of fifteen genes [inositol 1,4,5-triphosphate receptor (IP3R)1/2/3, ryanodine receptor (RYR)1/2, sarco/endoplasmic reticulum Ca2+ ATPase (SERCA)1/2/3, Na+/Ca2+ exchange (NCX)1/2/3, and plasma membrane Ca2+ ATPase (PMCA)1/2/3/4] associated with Ca2+ differences in expression were determined by quantitative reverse transcription-polymerase chain reaction. Changes in IP3R2, RYR1, SERCA2, NCX3, PMCA1, and PMCA3 gene expressions were observed in iron treatment of MDAH/DDP cells, while changes were detected in iron treatment of MDAH cells in IP3R1/2/3, RYR1/2, SERCA1/2/3, NCX2/3, and PMCA1 expressions. Conclusions: This changes in the expression of calcium channels, pumps, and exchange proteins in the epithelial ovarian cancer cell line and in cisplatin-resistant epithelial ovarian cancer cells suggest that iron may have an important role in regulating calcium homeostasis. Due to differences in the expression of genes that play of an important role in the regulation of calcium homeostasis in the effect of iron, drug resistance can be prevented by introducing a new perspective on the use of inhibitors and activators of these genes and thus cytostatic treatment strategies.

Exploration of the Modulatory Property Mechanism of ELeng Capsule in the Treatment of Endometriosis Using Transcriptomics Combined With Systems Network Pharmacology

Endometriosis is a common gynecological disease and causes severe chronic pelvic pain and infertility. Growing evidence showed that traditional Chinese medicine (TCM) plays an active role in the treatment of endometriosis. ELeng Capsule (ELC) is a Chinese medicine formula used for the treatment of endometriosis for several years. However, the mechanisms of ELC have not been fully characterized. In this study, network pharmacology and mRNA transcriptome analysis were used to study various therapeutic targets in ELC. As a result, 40 compounds are identified, and 75 targets overlapped with endometriosis-related proteins. The mechanism of ELC for the treatment of endometriosis is based on the function modules of inducing apoptosis, inhibiting angiogenesis, and regulating immunity mainly through signaling molecules and interaction (neuroactive ligand-receptor interaction), immune system-associated pathways (toll-like receptor signaling pathway), vascular endothelial growth factor (VEGF) signaling, and MAPK signaling pathway based on network pharmacology. In addition, based on RNA-sequence analysis, we found that the mechanism of ELC was predominantly associated with the regulation of the function modules of actin and cytoskeleton, epithelial-mesenchymal transition (EMT), focal adhesion, and immunity-associated pathways. In conclusion, ELC exerted beneficial effects on endometriosis, and the potential mechanism could be realized through functional modules, such as inducing apoptosis and regulating angiogenesis, cytoskeleton, and EMT. This work not only provides insights into the therapeutic mechanism of TCM for treating endometriosis but also offers an efficient way for drug discovery and development from herbal medicine.

Finding possible pharmacological effects of identified organic compounds in medicinal waters (BTEX and phenolic compounds)

Medicinal thermal waters consist of a mixture of different organic and inorganic compounds. Traditionally, these waters are only characterized and classified by their inorganic composition; however, the bioavailability of the majority of these inorganic compounds is limited. Many authors investigate the organic fractions of thermal waters. These authors propose that these compounds have a potential effect on health. To elucidate the underlying mechanisms, it is crucial to know the composition of the organic fractions. The absorption of these compounds on intact skin or mucosa is notable. Some of them have local anaesthetic effect or affect receptors in the central nervous system. In the knowledge of the chemical composition, we are able to estimate the possible pharmacological effect or might be able to assess possible toxicity risks. In the present article, we aim to review possible health effects of two of the identified organic fractions: benzene and alkylbenzenes and phenolic compounds that might correlate with the therapeutic effect on rheumatological or other diseases.

Using NGS-methylation profiling to understand the molecular pathogenesis of young MI patients who have subsequent cardiac events

Globally, ischaemic heart disease is a major contributor to premature morbidity and mortality. A significant number of young Myocardial Infarction (MI) patients (aged <55 y) have subsequent cardiac events within a year of their index event. This study used Next Generation Sequencing (NGS) methylation to understand the pathogenesis in this subset of young MI patients, comparing them to a cohort of patients without recurrent events. Cases and controls were matched for age, gender, ethnicity, and comorbidities. Differential methylation analyses were performed on Reduced Representation Bisulphite Sequencing (RRBS) data. Across the group and within case-control pairs' variation were analysed. Pairwise comparisons across each matched case-control pair resulted in a list of genes that were consistently significantly differentially methylated between all 16 matched pairs. This gene list was input into pathway analysis databases. Of particular relevance to cardiac pathology the following pathways were identified as over-represented in the patients with recurrent events; cell adhesion, transcription regulation and cardiac electrical conduction, specifically relating to calcium channel activity. This study looked at methylation differences between two populations of young MI patients. There were significantly different methylation profiles between the two groups studied; key pathways were identified as specifically affected in the patients with recurrent cardiac events. Matched pairwise comparisons and detailed interpretations of DNA methylation data may help to elucidate complex pathogeneses within and between clinical subtypes. Further analysis will determine whether these epigenomic differences can be useful as predictive biomarkers of clinical progression.