Promoter Methylation Analysis Reveals That KCNA5 Ion Channel Silencing Supports Ewing Sarcoma Cell Proliferation

Chimeric protein EWS::FLI1 drives cell proliferation in Ewing Sarcoma via aberrant expression of KCNN1/SK1 and dysregulation of calcium signaling

Ewing sarcoma (ES) is characterized by EWS::FLI1 or EWS::ERG fusion proteins. Knowing that ion channels are involved in tumorigenesis, this work aimed to study the involvement of the KCNN1 gene, which encodes the SK1 potassium channel, in ES development. Bioinformatics analyses from databases were used to study KCNN1 expression in patients and cell lines. Molecular approaches and in vitro assays were used to study the transcriptional regulation of KCNN1 and its involvement in the regulation of ES cell proliferation. KCNN1 is overexpressed in ES patient biopsies, and its expression is inversely correlated with patient survival. EWS::FLI1, like EWS::ERG, promotes KCNN1 and SK1 expression, binding to GGAA microsatellites near the promoter of KCNN1 isoforms. KCNN1 is involved in the regulation of ES cell proliferation, with its silencing being associated with a slowing of the cell cycle, and its expression modulates membrane potential and therefore calcium flux. These results highlight that KCNN1 is a direct target of EWS::FLI1 and EWS::ERG and demonstrate that KCNN1 is involved in the regulation of intracellular calcium activity and ES cell proliferation, making it a promising therapeutic target in ES.

Targeting DNA Methylation Machinery in Pediatric Solid Tumors

DNA methylation is a key epigenetic regulatory mechanism that plays a critical role in a variety of cellular processes, including the regulation of cell fate during development, maintenance of cell identity, and genome stability. DNA methylation is tightly regulated by enzymatic reactions and its deregulation plays an important role in the development of cancer. Specific DNA methylation alterations have been found in pediatric solid tumors, providing new insights into the development of these tumors. In addition, DNA methylation profiles have greatly contributed to tune the diagnosis of pediatric solid tumors and to define subgroups of patients with different risks of progression, leading to the reduction in unwanted toxicity and the improvement of treatment efficacy. This review highlights the dysregulated DNA methylome in pediatric solid tumors and how this information provides promising targets for epigenetic therapies, particularly inhibitors of DNMT enzymes (DNMTis). Opportunities and limitations are considered, including the ability of DNMTis to induce viral mimicry and immune signaling by tumors. Besides intrinsic action against cancer cells, DNMTis have the potential to sensitize immune-cold tumors to immunotherapies and may represent a remarkable option to improve the treatment of challenging pediatric solid tumors.

A Meta-Analysis Study to Infer Voltage-Gated K+ Channels Prognostic Value in Different Cancer Types

Potassium channels are often highly expressed in cancer cells with respect to healthy ones, as they provide proliferative advantages through modulating membrane potential, calcium homeostasis, and various signaling pathways. Among potassium channels, Shaker type voltage-gated Kv channels are emerging as promising pharmacological targets in oncology. Here, we queried publicly available cancer patient databases to highlight if a correlation exists between Kv channel expression and survival rate in five different cancer types. By multiple gene comparison analysis, we found a predominant expression of KCNA2, KCNA3, and KCNA5 with respect to the other KCNA genes in skin cutaneous melanoma (SKCM), uterine corpus endometrial carcinoma (UCEC), stomach adenocarcinoma (STAD), lung adenocarcinoma (LUAD), and lung squamous cell carcinoma (LUSC). This analysis highlighted a prognostic role of KCNA3 and KCNA5 in SKCM, LUAD, LUSC, and STAD, respectively. Interestingly, KCNA3 was associated with a positive prognosis in SKCM and LUAD but not in LUSC. Results obtained by the analysis of KCNA3-related differentially expressed genes (DEGs); tumor immune cell infiltration highlighted differences that may account for such differential prognosis. A meta-analysis study was conducted to investigate the role of KCNA channels in cancer using cancer patients’ datasets. Our study underlines a promising correlation between Kv channel expression in tumor cells, in infiltrating immune cells, and survival rate.

Relevance of Abnormal KCNN1 Expression and Osmotic Hypersensitivity in Ewing Sarcoma

Ewing sarcoma (EwS) is a rare and highly malignant bone tumor occurring mainly in childhood and adolescence. Physiologically, the bone is a central hub for Ca2+ homeostasis, which is severely disturbed by osteolytic processes in EwS. Therefore, we aimed to investigate how ion transport proteins involved in Ca2+ homeostasis affect EwS pathophysiology. We characterized the expression of 22 candidate genes of Ca2+-permeable or Ca2+-regulated ion channels in three EwS cell lines and found the Ca2+-activated K+ channel KCa2.1 (KCNN1) to be exceptionally highly expressed. We revealed that KCNN1 expression is directly regulated by the disease-driving oncoprotein EWSR1-FL1. Due to its consistent overexpression in EwS, KCNN1 mRNA could be a prognostic marker in EwS. In a large cohort of EwS patients, however, KCNN1 mRNA quantity does not correlate with clinical parameters. Several functional studies including patch clamp electrophysiology revealed no evidence for KCa2.1 function in EwS cells. Thus, elevated KCNN1 expression is not translated to KCa2.1 channel activity in EwS cells. However, we found that the low K+ conductance of EwS cells renders them susceptible to hypoosmotic solutions. The absence of a relevant K+ conductance in EwS thereby provides an opportunity for hypoosmotic therapy that can be exploited during tumor surgery.

Diagnostic and therapeutic biomarkers in colorectal cancer: a review

Colorectal cancer (CRC) is a public health concern and the second most common type of cancer among men and women causing a significant mortality. Biomarkers closely linked to the disease morbidity could holds potential as diagnostic and/or prognostic biomarker for the disease. This review provides an overview of recent advances in the search for colorectal cancer biomarkers through genomics and proteomics according to clinical function and application. Specifically, a number of biomarkers were identified and discussed. Emphasis was placed on their clinical applications relative to the diagnosis and prognosis of CRC. The discovery of more sensitive and specific markers for CRC is an urgent need, and the study of molecular targets is extremely important in this process, as they will allow for a better understanding of colorectal carcinogenesis, identification and validation of potential genetic signatures.

Potassium and Chloride Ion Channels in Cancer: A Novel Paradigm for Cancer Therapeutics

Cancer is a collection of diseases caused by specific changes at the genomic level that support cell proliferation indefinitely. Traditionally, ion channels are known to control a variety of cellular processes including electrical signal generation and transmission, secretion, and contraction by controlling ionic gradients. However, recent studies had brought to light important facts on ion channels in cancer biology.In this review we discuss the mechanism linking potassium or chloride ion channel activity to biochemical pathways controlling proliferation in cancer cells and the potential advantages of targeting ion channels as an anticancer therapeutic option.

Mitochondrial K+ channels and their implications for disease mechanisms

The field of mitochondrial ion channels underwent a rapid development during the last decade, thanks to the molecular identification of some of the nuclear-encoded organelle channels and to advances in strategies allowing specific pharmacological targeting of these proteins. Thereby, genetic tools and specific drugs aided definition of the relevance of several mitochondrial channels both in physiological as well as pathological conditions. Unfortunately, in the case of mitochondrial K⁺ channels, efforts of genetic manipulation provided only limited results, due to their dual localization to mitochondria and to plasma membrane in most cases. Although the impact of mitochondrial K⁺ channels on human diseases is still far from being genuinely understood, pre-clinical data strongly argue for their substantial role in the context of several pathologies, including cardiovascular and neurodegenerative diseases as well as cancer. Importantly, these channels are druggable targets, and their in-depth investigation could thus pave the way to the development of innovative small molecules with huge therapeutic potential. In the present review we summarize the available experimental evidence that mechanistically link mitochondrial potassium channels to the above pathologies and underline the possibility of exploiting them for therapy.

Selective expression of KCNA5 and KCNB1 genes in gastric and colorectal carcinoma

Background

Gastric and colorectal cancers are the most common malignant tumours, leading to a significant number of cancer-related deaths worldwide. Recently, increasing evidence has demonstrated that cancer cells exhibit a differential expression of potassium channels and this can contribute to cancer progression. However, their expression and localisation at the somatic level remains uncertain. In this study, we have investigated the expression levels of KCNB1 and KCNA5 genes encoding ubiquitous Kv2.1 and Kv1.5 potassium channels in gastric and colorectal tumours.

Methods

Gastric and colorectal tumoral and peritumoral tissues were collected to evaluate the expression of KCNB1 and KCNA5 mRNA by quantitative PCR. Moreover, the immunohistochemical staining profile of Kv2.1 and Kv1.5 was assessed on 40 Formalin-Fixed and Paraffin-Embedded (FFPE) gastric carcinoma tissues. Differences in gene expression between tumoral and peritumoral tissues were compared statistically with the Mann-Whitney U test. The association between the clinicopathological features of the GC patients and the expression of both Kv proteins was investigated with χ2 and Fisher’s exact tests.

Results

The mRNA fold expression of KCNB1 and KCNA5 genes showed a lower mean in the tumoral tissues (0.06 ± 0.17, 0.006 ± 0.009) compared to peritumoral tissues (0.08 ± 0.16, 0.16 ± 0.48, respectively) without reaching the significance rate (p = 0.861, p = 0.152, respectively). Interestingly, Kv2.1 and Kv1.5 immunostaining was detectable and characterised by a large distribution in peritumoral and tumoral epithelial cells. More interestingly, inflammatory cells were also stained. Surprisingly, Kv2.1 and Kv1.5 staining was undoubtedly and predominantly detected in the cytoplasm compartment of tumour cells. Indeed, the expression of Kv2.1 in tumour cells revealed a significant association with the early gastric cancer clinical stage (p = 0.026).

Conclusion

The data highlight, for the first time, the potential role of Kv1.5 and Kv2.1 in gastrointestinal-related cancers and suggests they may be promising prognostic markers for these tumours.

Genome-wide methylation sequencing identifies progression-related epigenetic drivers in myelodysplastic syndromes

The potential mechanism of myelodysplastic syndromes (MDS) progressing to acute myeloid leukemia (AML) remains poorly elucidated. It has been proved that epigenetic alterations play crucial roles in the pathogenesis of cancer progression including MDS. However, fewer studies explored the whole-genome methylation alterations during MDS progression. Reduced representation bisulfite sequencing was conducted in four paired MDS/secondary AML (MDS/sAML) patients and intended to explore the underlying methylation-associated epigenetic drivers in MDS progression. In four paired MDS/sAML patients, cases at sAML stage exhibited significantly increased methylation level as compared with the matched MDS stage. A total of 1090 differentially methylated fragments (DMFs) (441 hypermethylated and 649 hypomethylated) were identified involving in MDS pathogenesis, whereas 103 DMFs (96 hypermethylated and 7 hypomethylated) were involved in MDS progression. Targeted bisulfite sequencing further identified that aberrant GFRA1, IRX1, NPY, and ZNF300 methylation were frequent events in an additional group of de novo MDS and AML patients, of which only ZNF300 methylation was associated with ZNF300 expression. Subsequently, ZNF300 hypermethylation in larger cohorts of de novo MDS and AML patients was confirmed by real-time quantitative methylation-specific PCR. It was illustrated that ZNF300 methylation could act as a potential biomarker for the diagnosis and prognosis in MDS and AML patients. Functional experiments demonstrated the anti-proliferative and pro-apoptotic role of ZNF300 overexpression in MDS-derived AML cell-line SKM-1. Collectively, genome-wide DNA hypermethylation were frequent events during MDS progression. Among these changes, ZNF300 methylation, a regulator of ZNF300 expression, acted as an epigenetic driver in MDS progression. These findings provided a theoretical basis for the usage of demethylation drugs in MDS patients against disease progression.

RING1B recruits EWSR1-FLI1 and cooperates in the remodeling of chromatin necessary for Ewing sarcoma tumorigenesis

Ewing sarcoma (EwS) is an aggressive tumor that affects adolescents and young adults. EwS is defined by a chromosomal translocation, EWSR1-FLI1 being the most common, that causes genome reprogramming through remodeling of enhancers. Here, we describe an unexpected function of RING1B, which is highly expressed in EwS. While retaining its repressive activity at Polycomb developmental regulated genes, RING1B colocalizes with EWSR1-FLI1 at active enhancers. We demonstrate that RING1B is necessary for the expression of key EWSR1-FLI1 targets by facilitating oncogene recruitment to their enhancers. Knockdown of RING1B impairs growth of tumor xenografts and expression of genes regulated by EWSR1-FLI1 bound enhancers. Pharmacological inhibition of AURKB with AZD1152 increases H2Aub levels causing down-regulation of RING1B/EWSR1-FLI1 common targets. Our findings demonstrate that RING1B is a critical modulator of EWSR1-FLI1-induced chromatin remodeling, and its inhibition is a potential therapeutic strategy for the treatment of these tumors.

MiR-3940-5p promotes granulosa cell proliferation through targeting KCNA5 in polycystic ovarian syndrome

Increased granulosa cell (GC) proliferation may contribute to abnormal folliculogenesis in patients with polycystic ovary syndrome (PCOS), which affects approximately 10% reproductive aged women. However, the mechanisms underlying increased GC proliferation in PCOS remain incompletely understood. In this study, we identified miR-3940-5p as a hub miRNA in GC from PCOS using weighted gene co-expression network analysis (WGCNA), and real-time polymerase chain reaction (RT-PCR) analysis confirmed that miR-3940-5p was significantly increased in GC from PCOS. Enrichment analysis of predicted target genes of miR-3940-5p indicated potential roles of miR-3940-5p in follicular development and cell proliferation regulation. Consistently, functional study confirmed that miR-3940-5p overexpression promoted granulosa cell proliferation. Integrated analysis of mRNA expression profiling data and predicted target genes of miR-3940-5p identified potassium voltage-gated channel subfamily A member 5 (KCNA5) as a potential target of miR-3940-5p, and was validated by luciferase reporter assay. Finally, functional analysis suggested that miR-3940-5p promoted GC proliferation in a KCNA5 dependent manner. In conclusion, miR-3940-5p was a hub miRNA upregulated in GC from PCOS, and promoted GC proliferation by targeting KCNA5.

Ion channels in sarcoma: pathophysiology and treatment options

Sarcomas are characterized by aggressive growth and a high metastasis potentially leading in most cases to a lethal outcome. These malignant tumors of the connective tissue have a high heterogeneity with numerous genetic mutations resulting in more than 100 types of sarcoma that can be grouped into two main kinds: soft tissue sarcoma and bone sarcoma. Sarcomas are often diagnosed at late disease stage, whereas a guaranteed diagnosis of the sarcoma type is fundamental for successful therapy. However, there is no appropriate therapy available. Therefore, the need for new therapies, which prolong survival and improve quality of life, is high. In the last two decades, the role of ion channels in cancer has emerged. Ion channels seem to be an ideal target for anti-tumor therapies. However, different cancer types have their own altered ion channel pattern, and the knowledge about the tumor-associated ion channel expression is fundamental. Here, we focus on the role of different ion channels in sarcoma, their pathophysiology, and possible treatment options.

Genes CEP55, FOXD3, FOXF2, GNAO1, GRIA4, and KCNA5 as potential diagnostic biomarkers in colorectal cancer

Background

Colorectal cancer (CRC) is one of the leading causes of death by cancer worldwide and in need of novel potential diagnostic biomarkers for early discovery.

Methods

We conducted a two-step study. We first employed bioinformatics on data from The Cancer Genome Atlas to obtain potential biomarkers and then experimentally validated some of them on our clinical samples. Our aim was to find a methylation alteration common to all clusters, with the potential of becoming a diagnostic biomarker in CRC.

Results

Unsupervised clustering of methylation data resulted in four clusters, none of which had a known common genetic or epigenetic event, such as mutations or methylation. The intersect among clusters and regulatory regions resulted in 590 aberrantly methylated probes, belonging to 198 differentially expressed genes. After performing pathway and functional analysis on differentially expressed genes, we selected six genes: CEP55, FOXD3, FOXF2, GNAO1, GRIA4 and KCNA5, for further experimental validation on our own clinical samples. In silico analysis demonstrated that CEP55 was hypomethylated in 98.7% and up-regulated in 95.0% of samples. Genes FOXD3, FOXF2, GNAO1, GRIA4 and KCNA5 were hypermethylated in 97.9, 81.1, 80.3, 98.4 and 94.0%, and down-regulated in 98.3, 98.9, 98.1, 98.1 and 98.6% of samples, respectively. Our experimental data show CEP55 was hypomethylated in 97.3% of samples and down-regulated in all samples, while FOXD3, FOXF2, GNAO1, GRIA4 and KCNA5 were hypermethylated in 100.0, 90.2, 100.0, 99.1 and 100.0%, and down-regulated in 68.0, 76.0, 96.0, 95.2 and 84.0% of samples, respectively. Results of in silico and our experimental analyses showed that more than 97% of samples had at least four methylation markers altered.

Conclusions

Using bioinformatics followed by experimental validation, we identified a set of six genes that were differentially expressed in CRC compared to normal mucosa and whose expression seems to be methylation dependent. Moreover, all of these six genes were common in all methylation clusters and mutation statuses of CRC and as such are believed to be an early event in human CRC carcinogenesis and to represent potential CRC biomarkers.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0501-z) contains supplementary material, which is available to authorized users.

Long Noncoding RNA CPR (Cardiomyocyte Proliferation Regulator) Regulates Cardiomyocyte Proliferation and Cardiac Repair

BACKGROUND

The adult mammalian cardiomyocytes lose their proliferative capacity, which is responsible for cardiac dysfunction and heart failure following injury. The molecular mechanisms underlying the attenuation of adult cardiomyocyte proliferation remain largely unknown. Because long noncoding RNAs (lncRNAs) have a critical role in the development of cardiovascular problems, we investigated whether lncRNAs have any role in the regulation of cardiomyocyte proliferation and cardiac repair.

METHODS

Using bioinformatics and initial analysis, we identified an lncRNA, named CPR (cardiomyocyte proliferation regulator), that has a potential regulatory role in cardiomyocyte proliferation. For in vivo experiments, we generated CPR knockout and cardiac-specific CPR-overexpressing mice. In isolated cardiomyocytes, we used adenovirus for silencing (CPR-small interfering RNA) or overexpressing CPR. To investigate the mechanisms of CPR function in cardiomyocyte proliferation, we performed various analyses including quantitative reverse transcription-polymerase chain reaction, Western blot, histology, cardiac function (by echocardiography), transcriptome analyses (microarray assay), RNA pull-down assay, and chromatin immunoprecipitation assay.

RESULTS

CPR level is comparatively higher in the adult heart than in the fetal stage. The silencing of CPR significantly increased cardiomyocyte proliferation in postnatal and adult hearts. Moreover, CPR deletion restored the heart function after myocardial injury, which was evident from increased cardiomyocyte proliferation, improvement of myocardial function, and reduced scar formation. In contrast, the neonatal cardiomyocyte proliferation and cardiac regeneration were remarkably suppressed in CPR-overexpressing mice or adeno-associated virus serotype 9-CPR-overexpressing heart. These results indicate that CPR acts as a negative regulator of cardiomyocyte proliferation and regeneration. Next, we found that CPR targets minichromosome maintenance 3, an initiator of DNA replication and cell cycle progression, to suppress cardiomyocyte proliferation. CPR silenced minichromosome maintenance 3 expression through directly interacting and recruiting DNMT3A to its promoter cysteine-phosphate-guanine sites, as evident from decreased minichromosome maintenance 3 promoter methylation and increased minichromosome maintenance 3 expression in CPR knocked-down cardiomyocytes and CPR knockout mouse heart. These results were confirmed in CPR-overexpressing cardiomyocytes and CPR-overexpressing mouse heart.

CONCLUSIONS

Together, our findings identified that CPR is a suppressor of cardiomyocyte proliferation and indicated that lncRNAs take part in the regulation of cardiomyocyte proliferation and cardiac repair. Our study provides an lncRNA-based therapeutic strategy for effective cardiac repair and regeneration.

Implication of Voltage-Gated Potassium Channels in Neoplastic Cell Proliferation

Voltage-gated potassium channels (Kv) are the largest group of ion channels. Kv are involved in controlling the resting potential and action potential duration in the heart and brain. Additionally, these proteins participate in cell cycle progression as well as in several other important features in mammalian cell physiology, such as activation, differentiation, apoptosis, and cell volume control. Therefore, Kv remarkably participate in the cell function by balancing responses. The implication of Kv in physiological and pathophysiological cell growth is the subject of study, as Kv are proposed as therapeutic targets for tumor regression. Though it is widely accepted that Kv channels control proliferation by allowing cell cycle progression, their role is controversial. Kv expression is altered in many cancers, and their participation, as well as their use as tumor markers, is worthy of effort. There is an ever-growing list of Kv that remodel during tumorigenesis. This review focuses on the actual knowledge of Kv channel expression and their relationship with neoplastic proliferation. In this work, we provide an update of what is currently known about these proteins, thereby paving the way for a more precise understanding of the participation of Kv during cancer development.

Planarian regeneration as a model of anatomical homeostasis: Recent progress in biophysical and computational approaches

Planarian behavior, physiology, and pattern control offer profound lessons for regenerative medicine, evolutionary biology, morphogenetic engineering, robotics, and unconventional computation. Despite recent advances in the molecular genetics of stem cell differentiation, this model organism's remarkable anatomical homeostasis provokes us with truly fundamental puzzles about the origin of large-scale shape and its relationship to the genome. In this review article, we first highlight several deep mysteries about planarian regeneration in the context of the current paradigm in this field. We then review recent progress in understanding of the physiological control of an endogenous, bioelectric pattern memory that guides regeneration, and how modulating this memory can permanently alter the flatworm's target morphology. Finally, we focus on computational approaches that complement reductive pathway analysis with synthetic, systems-level understanding of morphological decision-making. We analyze existing models of planarian pattern control and highlight recent successes and remaining knowledge gaps in this interdisciplinary frontier field.

Stressing the (Epi)Genome: Dealing with Reactive Oxygen Species in Cancer

SIGNIFICANCE

Growing evidence indicates cross-talk between reactive oxygen species (ROS) and several key epigenetic processes such as DNA methylation, histone modifications, and miRNAs in normal physiology and human pathologies including cancer. This review focuses on how ROS-induced oxidative stress, metabolic intermediates, and epigenetic processes influence each other in various cancers. Recent Advances: ROS alter chromatin structure and metabolism that impact the epigenetic landscape in cancer cells. Several site-specific DNA methylation changes have been identified in different cancers and are discussed in the review. We also discuss the interplay of epigenetic enzymes and miRNAs in influencing malignant transformation in an ROS-dependent manner.

CRITICAL ISSUES

Loss of ROS-mediated signaling mostly by epigenetic regulation may promote tumorigenesis. In contrast, augmented oxidative stress because of high ROS levels may precipitate epigenetic alterations to effect various phases of carcinogenesis. We address both aspects in the review.

FUTURE DIRECTIONS

Several drugs targeting ROS are under various stages of clinical development. Recent analysis of human cancers has revealed pervasive deregulation of the epigenetic machinery. Thus, a better understanding of the cross-talk between ROS and epigenetic alterations in cancer could lead to the identification of new drug targets and more effective treatment modalities.

The body electric 2.0: recent advances in developmental bioelectricity for regenerative and synthetic bioengineering

Breakthroughs in biomedicine and synthetic bioengineering require predictive, rational control over anatomical structure and function. Recent successes in manipulating cellular and molecular hardware have not been matched by progress in understanding the patterning software implemented during embryogenesis and regeneration. A fundamental capability gap is driving desired changes in growth and form to address birth defects and traumatic injury. Here we review new tools, results, and conceptual advances in an exciting emerging field: endogenous non-neural bioelectric signaling, which enables cellular collectives to make global decisions and implement large-scale pattern homeostasis. Spatially distributed electric circuits regulate gene expression, organ morphogenesis, and body-wide axial patterning. Developmental bioelectricity facilitates the interface to organ-level modular control points that direct patterning in vivo. Cracking the bioelectric code will enable transformative progress in bioengineering and regenerative medicine.

Targeting Mitochondrial Ion Channels to Fight Cancer

In recent years, several experimental evidences have underlined a new role of ion channels in cancer development and progression. In particular, mitochondrial ion channels are arising as new oncological targets, since it has been proved that most of them show an altered expression during tumor development and the pharmacological targeting of some of them have been demonstrated to be able to modulate cancer growth and progression, both in vitro as well as in vivo in pre-clinical mouse models. In this scenario, pharmacology of mitochondrial ion channels would be in the near future a new frontier for the treatment of tumors. In this review, we discuss the new advances in the field, by focusing our attention on the improvements in new drug developments to target mitochondrial ion channels.

Dimethylation of Histone 3 Lysine 9 is sensitive to the epileptic activity, and affects the transcriptional regulation of the potassium channel Kcnj10 gene in epileptic rats

Potassium channels can be affected by epileptic seizures and serve a crucial role in the pathophysiology of epilepsy. Dimethylation of histone 3 lysine 9 (H3K9me2) and its enzyme euchromatic histone‑lysine N‑methyltransferase 2 (G9a) are the major epigenetic modulators and are associated with gene silencing. Insight into whether H3K9me2 and G9a can respond to epileptic seizures and regulate expression of genes encoding potassium channels is the main purpose of the present study. A total of 16 subtypes of potassium channel genes in pilocarpine‑modelled epileptic rats were screened by reverse transcription‑quantitative polymerase chain reaction, and it was determined that the expression ATP‑sensitive inward rectifier potassium channel 10 (Kcnj10) increased in hippocampus and insular cortex, while the expression of most of the other subtypes decreased. The total level of H3K9me2 decreased in the model group compared with the control. The Kcnj10 gene encoding the Kir4.1 channel was selected to analyse changes in H3K9me2 in the promoter region by the chromatin immuno‑precipitation method. Anti‑H3K9me2 and anti‑G9a antibodies were used to identify the modified DNAs. Five primers were designed across the promoter region of the Kcnj10 gene. In epileptic hippocampi, the relative abundance of H3K9me2 and G9a in the promoter region of Kcnj10 decreased markedly. Removal of the H3K9me2 repressive mark resulted in decreased transcriptional inhibition of the Kcnj10 gene and therefore increased its expression. In the cultured C6 cells, specific inhibition of the enzymatic activity of G9a by 2‑(Hexahydro‑4‑methyl‑1H‑1,4‑diazepin‑1‑yl)‑6,7‑di‑ methoxy‑N‑(1‑(phenyl‑methyl)‑4‑piperidinyl)‑4‑quinazolinamine tri‑hydrochloride hydrate (bix01294) resulted in upregulation of the expression of Kir4.1 proteins. The present study demonstrated that H3K9me2 and G9a are sensitive to epileptic seizure activity during the acute phase of epilepsy and can affect the transcriptional regulation of the Kcnj10 channel.

Beyond the Electrocardiogram: Mutations in Cardiac Ion Channel Genes Underlie Nonarrhythmic Phenotypes

Cardiac ion channelopathies are an important cause of sudden death in the young and include long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, idiopathic ventricular fibrillation, and short QT syndrome. Genes that encode ion channels have been implicated in all of these conditions, leading to the widespread implementation of genetic testing for suspected channelopathies. Over the past half-century, researchers have also identified systemic pathologies that extend beyond the arrhythmic phenotype in patients with ion channel gene mutations, including deafness, epilepsy, cardiomyopathy, periodic paralysis, and congenital heart disease. A coexisting phenotype, such as cardiomyopathy, can influence evaluation and management. However, prior to recent molecular advances, our understanding and recognition of these overlapping phenotypes were poor. This review highlights the systemic and structural heart manifestations of the cardiac ion channelopathies, including their phenotypic spectrum and molecular basis.

Ewing sarcoma: a chronicle of molecular pathogenesis

Sarcomas have traditionally been classified according to their chromosomal alterations regardless of whether they accompany simple or complex genetic changes. Ewing sarcoma, a classic small round cell bone tumor, is a well-known mesenchymal malignancy that results from simple sarcoma-specific genetic alterations. The genetic alterations are translocations between genes of the TET/FET family (TLS/FUS, EWSR1, and TAF15) and genes of the E26 transformation-specific (ETS) family. In this review, we intend to summarize a chronicle of molecular findings of Ewing sarcoma including recent advances and explain resultant molecular pathogenesis.