ADAR1 forms a complex with Dicer to promote microRNA processing and RNA-induced gene silencing.

Adenosine deaminases acting on RNA (ADARs) are involved in RNA editing that converts adenosine residues to inosine specifically in double-stranded RNAs. In this study, we investigated the interaction of the RNA editing mechanism with the RNA interference (RNAi) machinery and found that ADAR1 forms a complex with Dicer through direct protein-protein interaction. Most importantly, ADAR1 increases the maximum rate (Vmax) of pre-microRNA (miRNA) cleavage by Dicer and facilitates loading of miRNA onto RNA-induced silencing complexes, identifying a new role of ADAR1 in miRNA processing and RNAi mechanisms. ADAR1 differentiates its functions in RNA editing and RNAi by the formation of either ADAR1/ADAR1 homodimer or Dicer/ADAR1 heterodimer complexes, respectively. As expected, the expression of miRNAs is globally inhibited in ADAR1(-/-) mouse embryos, which, in turn, alters the expression of their target genes and might contribute to their embryonic lethal phenotype.

Processing of Alu small RNAs by DICER/ADAR1 complexes and their RNAi targets.

In addition to adenosine-to-inosine RNA editing activities, ADAR1 has been shown to have various RNA editing-independent activities including modulation of RNAi efficacy. We previously reported that ADAR1 forms a heterodimer complex with DICER and facilitates processing of pre-miRNAs to mature miRNAs. In addition to miRNA synthesis, DICER is involved in processing of long dsRNAs into small RNAs (endo-siRNAs). Generation of retrotransposon-derived endo-siRNAs by DICER and their functions in regulation of transcripts in mouse oocytes has been previously reported. However, the synthesis and functions of endo-siRNAs in somatic cells remain largely unknown. Here, we report that ADAR1 together with DICER generates endogenous small RNAs, Alu endo-siRNAs by cleaving long double-stranded regions of inverted Alu repeats. We identified AGO2-loaded Alu endo-siRNAs, which are highly expressed in commonly used cell lines. These Alu endo-siRNAs carrying both sense and antisense Alu sequences seem to target a set of genes containing a single Alu sequence, either antisense or sense, respectively, within their 3'UTR. In silico screening identified potential RNA silencing target genes for these Alu endo-siRNAs. We present results of a proof-of-concept experiment, in which sense Alu endo-siRNAs derived from AluSz and AluJr family elements target CUB Domain Containing Protein 1 mRNAs containing an antisense copy of AluJb in their 3'UTRs and consequently induce apoptosis in HeLa cells. Our results clearly indicate that Alu endo-siRNAs are functional also in somatic cells.

Adenosine-to-inosine RNA editing in neurological development and disease.

Adenosine-to-inosine (A-to-I) editing is one of the most prevalent post-transcriptional RNA modifications in metazoan. This reaction is catalysed by enzymes called adenosine deaminases acting on RNA (ADARs). RNA editing is involved in the regulation of protein function and gene expression. The numerous A-to-I editing sites have been identified in both coding and non-coding RNA transcripts. These editing sites are also found in various genes expressed in the central nervous system (CNS) and play an important role in neurological development and brain function. Aberrant regulation of RNA editing has been associated with the pathogenesis of neurological and psychiatric disorders, suggesting the physiological significance of RNA editing in the CNS. In this review, we discuss the current knowledge of editing on neurological disease and development.

Important factors in left atrial posterior wall isolation using 28-mm cryoballoon ablation for persistent atrial fibrillation-Block line or isolation area?

INTRODUCTION: Left atrial (LA) roof ablation using the cryoballoon technique, combined with pulmonary vein isolation (PVI), has been reported to be beneficial for ablation therapy in patients with persistent atrial fibrillation (AF). Left posterior wall ablation also results in improved patient outcomes. However, the contribution of these techniques to the success of cryoballoon ablation (CBA) treatment of AF is not known. The present study examined the influence of the roofline block and isolation area on outcomes after CBA. METHODS AND RESULTS: We enrolled 78 patients with persistent AF. LA roof ablation was performed using a 28-mm cryoballoon with a single freezing of 3 minutes at each region (median number of freezes: 4) after PVI. After CBA, bipolar voltage amplitude mapping was performed during sinus rhythm using the NavX mapping system. Patients were divided into two subgroups according to the voltage and activation map: the roof-conduction (n = 46) and roofline-block groups (n = 32). Atrial tachyarrhythmia recurred in 20 patients of the conduction group and 4 patients of the roofline-block group. The rate of 12-month freedom from tachyarrhythmia after a single ablation procedure was 78% (95% confidence interval [CI], 60%-89%) in the roofline-block group and 45% (95% CI, 30%-60%) in the conduction group (P = .048). Cox proportional hazard analysis revealed that the isolated area was not a significant predictor of recurrence (hazard ratio, 0.94; 95% CI, 0.86-1.02; P = .15). CONCLUSION: Creating a complete roofline block is the major factor predicting the maintenance of sinus rhythm in patients with persistent AF.

Differences in Intravascular Ultrasound Measurement Values Between Treatment Modalities for Restenosis in Femoropopliteal Lesions.

BACKGROUND: The risk of restenosis after intervention is higher in femoropopliteal than in aortoiliac lesions. However, the appropriate endovascular therapy (EVT) for preventing restenosis after intervention for femoropopliteal lesions remains unknown. This study aimed to elucidate the relationship between lesion characteristics and patency after EVT using intravascular ultrasound (IVUS) measurement and to determine the predictors of restenosis on IVUS.Methods and Results:This prospective observational study was performed at 18 Japanese centers. We evaluated the lesion characteristics before and after EVT for femoropopliteal lesion using IVUS. Angiographic or duplex ultrasound follow-up was performed at 1 year after EVT. A total of 263 lesions underwent EVT between December 2016 and December 2017. In total, 20 lesions (8 cases of isolated common femoral artery lesion and 12 cases of restenosis lesion) were excluded, and 243 lesions were enrolled in this study. A total of 181 lesions were treated with stent placement, and 62 lesions were treated only with balloon angioplasty. In the case of stent use, a larger distal plaque burden was associated with restenosis, while a lower calcification angle was associated with higher patency in the case of balloon angioplasty alone. CONCLUSIONS: The factors related to patency differed depending on the treating modality. The findings suggest that IVUS is a useful tool for predicting patency because it can provide a more accurate evaluation after EVT for femoropopliteal lesions.

[Use of Flash Glucose Monitoring during the Perioperative Period of Cardiac Surgery in a Patient with Type 1 Diabetes Mellitus].

FreeStyle Libre (flash glucose monitoring) is useful to control the blood sugar levels of outpatients with diabetes. We used FreeStyle Libre for a patient with type 1 diabetes mellitus during the perioperative period of cardiac surgery except during and just after surgery. We adjusted the insulin amount according to the glucose level of the device before surgery and prevented prolonged hypoglycemia. After surgery, we could also adjust the blood sugar levels using the device until discharge. All data were within zones A and B of the Clarke error grid analysis when referred to as arterial blood sugar levels in the intensive care unit. In the general ward after surgery, 95% of the data referred to as venous blood sugar levels were within zones A and B. FreeStyle Libre was useful for adjusting the amount of insulin for a patient with type 1 diabetes mellitus during the perioperative period of cardiac surgery in the ward and also might be useful for decreasing the frequency of arterial blood collection in the intensive care unit.

A relation between ablation area and outcome of ablation using 28-mm cryoballon ablation: Importance of carina region.

INTRODUCTION: Pulmonary vein isolation (PVI) with wide antral ablation leads to better outcomes in atrial fibrillation ablation therapy, but the ablation area is relatively small during cryoballoon ablation (CBA). The present study tested the hypothesis that wide ablation can lead to better outcomes in CBA. METHODS AND RESULTS: Ninety-six patients with atrial fibrillation were enrolled (paroxysmal 76%, 64.1 ± 11.7 years). All patients underwent preprocedural computed tomography and the PV diameter at left atrial PV junction was measured. PV isolation was performed using a 28-mm CB for 3 minutes with single freezing. Sinus rhythm bipolar voltage amplitude maps with the NavX mapping system were generated after ablation. According to the voltage map, patients were divided into 3 subgroups (68 in the extensive isolation group, 17 in the individual isolation group, and 10 in the incomplete isolation group). Atrial tachyarrhythmias recurred in 9 patients of the extensive isolation group and 6 in the individual isolation group. The rate of 12-month freedom from tachyarrhythmia after a single ablation procedure was 84% (95% confidence interval [C.I.], 72%-91%) in the extensive group and 57% (95% C.I., 28%-78%) in the individual group (P = 0.048). Multiple logistic regression analyses revealed that maximal PV diameter was the only predictor to achieve extensive PVI (odds ratio, 1.57; 95% C.I. 1.08-2.29 P = 0.018). CONCLUSION: Extensive isolation is superior to individual isolation for achieving freedom from atrial arrhythmia in long term follow-up by CBA. Evaluating PV diameter at the left atrial PV junction is essential for applying CBA.

A biochemical landscape of A-to-I RNA editing in the human brain transcriptome.

Inosine is an abundant RNA modification in the human transcriptome and is essential for many biological processes in modulating gene expression at the post-transcriptional level. Adenosine deaminases acting on RNA (ADARs) catalyze the hydrolytic deamination of adenosines to inosines (A-to-I editing) in double-stranded regions. We previously established a biochemical method called "inosine chemical erasing" (ICE) to directly identify inosines on RNA strands with high reliability. Here, we have applied the ICE method combined with deep sequencing (ICE-seq) to conduct an unbiased genome-wide screening of A-to-I editing sites in the transcriptome of human adult brain. Taken together with the sites identified by the conventional ICE method, we mapped 19,791 novel sites and newly found 1258 edited mRNAs, including 66 novel sites in coding regions, 41 of which cause altered amino acid assignment. ICE-seq detected novel editing sites in various repeat elements as well as in short hairpins. Gene ontology analysis revealed that these edited mRNAs are associated with transcription, energy metabolism, and neurological disorders, providing new insights into various aspects of human brain functions.

Elucidating the inosinome: global approaches to adenosine-to-inosine RNA editing.

Catalysed by members of the adenosine deaminase acting on RNA (ADAR) family of enzymes, adenosine-to-inosine (A-to-I) editing converts adenosines in RNA molecules to inosines, which are functionally equivalent to guanosines. Recently, global approaches to studying this widely conserved phenomenon have emerged. The use of bioinformatics, high-throughput sequencing and other approaches has increased the number of known editing sites by several orders of magnitude, and we now have a greater understanding of the control and the biological significance of editing. This Progress article reviews some of these recent global studies and their results.

Regional Differences in Frequency of Warfarin Therapy and Thromboembolism in Japanese Patients With Non-Valvular Atrial Fibrillation　- Analysis of the J-RHYTHM Registry.

BACKGROUND: The proportion of patients with atrial fibrillation (AF) treated with anticoagulation varies from country to country. In Japan, little is known about regional differences in frequency of warfarin use or prognosis among patients with non-valvular AF (NVAF). METHODS AND RESULTS: In J-RHYTHM Registry, the number of patients recruited from each of 10 geographic regions of Japan was based on region population density. A total of 7,406 NVAF patients were followed up prospectively for 2 years. At baseline, significant differences in various clinical characteristics including age, sex, type of AF, comorbidity, and CHADS2score, were detected among the regions. The highest mean CHADS2score was recorded in Shikoku. Frequency of warfarin use differed between the regions (P<0.001), with lower frequencies observed in Hokkaido and Shikoku. Baseline prothrombin time international normalized ratio differed slightly but significantly between the regions (P<0.05). On univariate analysis, frequency of thromboembolic events differed among the regions (P<0.001), with the highest rate seen in Shikoku. An inverse correlation was detected between frequency of thromboembolic and of major hemorrhagic events (P=0.062). On multivariate analysis, region emerged as an independent risk for thromboembolism. CONCLUSIONS: Thromboembolic risk, frequency of warfarin use, and intensity and quality of warfarin treatment differed significantly between geographic regions of Japan. Region was found to be an independent predictor of thromboembolic events. (Circ J 2016; 80: 1548-1555).

Efficacy of Dietitian-instructed Low Iodine Diet for Radioiodine Remnant Tissue Ablation for Thyroid Cancer.

We evaluated the significance of dietary instruction (DI) for patients who are going on a low iodine diet (LID) as a preparation for remnant tissue ablation for thyroid cancer. DI was done by a dietarian using a dedicated handbook we have developed. To assess the effect of LID on depleting body iodine, urinary iodine concentration (UIC) in patients with post-surgical papillary thyroid cancer was measured twice, before and after LID. UIC on the day of radioiodine administration was compared with radioiodine uptake (RU) in the remnant tissue. Additionally, the association between clinical and lifestyle-related features of patients and the outcome of LID were investigated. A questionnaire survey was conducted to determine whether the DI helped patients go on LID. The mean value of UIC after the one-week LID was decreased to about 15% of the baseline value. There was a significant inverse correlation between UIC and RU (r= -0.694). Age and UIC before the start of LID were linked to successful outcome of LID. In the questionnaire survey, 84% of the participants answered that the handbook helped them go on a LID. Likewise, 80% answered that they could manage their LID without using the boil-in-the-bag low iodine food. LID successfully decreased UIC in patients undergoing remnant tissue ablation. DI by a dietitian may make a practice of LID easier.

ICLAMP: a novel technique to explore adenosine deamination via inosine chemical labeling and affinity molecular purification.

Recent developments in sequencing and bioinformatics have advanced our understanding of adenosine-to-inosine (A-to-I) RNA editing. Surprisingly, recent analyses have revealed the capability of adenosine deaminase acting on RNA (ADAR) to edit DNA:RNA hybrid strands. However, edited inosines in DNA remain largely unexplored. A precise biochemical method could help uncover these potentially rare DNA editing sites. We explore maleimide as a scaffold for inosine labeling. With fluorophore-conjugated maleimide, we were able to label inosine in RNA or DNA. Moreover, with biotin-conjugated maleimide, we purified RNA and DNA containing inosine. Our novel technique of inosine chemical labeling and affinity molecular purification offers substantial advantages and provides a versatile platform for further discovery of A-to-I editing sites in RNA and DNA.

Factors Related to Favorable Outcomes in Older Adults Undergoing Home-Visit Rehabilitation Therapy.

BACKGROUND: Increasing elderly population is a major health concern worldwide, requiring various at-home care services. The aim of home-visit rehabilitation therapy is to support at-home living of the elderly and to promote their participation in social activities. There is a paucity of data about the clinical conditions of this population that can contribute to the achievement of goals in-home visit rehabilitation therapy. AIM: This study aimed to clarify clinical variables that could be related to the achievement of goals in-home visit rehabilitation therapy. METHODS: We collected retrospective clinical data of the older adults who underwent home-visit rehabilitation therapy between July 2006 and June 2021. We searched the clinical variables of home-visit rehabilitation therapy users and their frequency of utilization of home-visit rehabilitation therapy services from the clinical record. The initial and final clinical variables evaluated in this study included the abilities of daily living, degree of being bedridden, dementia rating, and levels of support or long-term care. Those variables were evaluated by rehabilitation therapists and doctors. The users were divided into three groups according to the reason for terminating rehabilitation therapy: goal achievement (achieved group), aggravation of underlying disease (aggravated group), and treatment suspension because of their own/others' wish (suspended group). The clinical parameters concerning the rehabilitation program, care level, and activities of daily living were evaluated among the groups. The clinical parameters concerning the rehabilitation program, care level, and activities of daily living were statistically evaluated among those three groups, using the chi-square test and Kruskal-Wallis test. RESULTS: In the achieved, aggravated, and suspended groups, 45, 190, and 38 users were respectively enrolled. The aggravated group showed significantly higher final care level (p = 0.002), degree of being bedridden (p=0.001), and dementia rating (p = 0.017) and significantly lower Barthel index scores (p < 0.001) and Frenchay Activities Index scores (p = 0.001) than the achieved group. Persons requesting the therapy were significantly older adults themselves in the achieved group (p = 0.018). The therapy was significantly performed more than once per week in the achieved group (p = 0.018). CONCLUSIONS: Older adults undergoing self-motivated home-visit rehabilitation therapy more than once per week may contribute to the achievement of the goal.

Antagonistic and stimulative roles of ADAR1 in RNA silencing.

Adenosine deaminases acting on RNA (ADARs) are involved in RNA editing that converts adenosine residues to inosine specifically in double-stranded RNAs (dsRNA). This A-to-I RNA editing pathway and the RNA interference (RNAi) pathway seem to interact antagonistically by competing for their common dsRNA substrates. For instance, A-to-I editing of certain microRNA (miRNA) precursors by ADAR1 and ADAR2 inhibits their processing to mature miRNAs. Recent studies unexpectedly revealed the presence of a completely different type of interaction between the RNA editing mechanism and the RNAi machinery. ADAR1 forms a complex via direct protein-protein interaction with Dicer, an RNase III gene family member involved in the RNAi mechanism. ADAR1 in the Dicer complex promotes pre-miRNA cleavage by Dicer and facilitates loading of miRNA onto RNA-induced silencing complexes, giving rise to an unsuspected stimulative function of ADAR1 on miRNA processing and RNAi mechanisms. ADAR1 differentiates its functions in RNA editing and RNAi by formation of either ADAR1-ADAR1 homodimer or Dicer-ADAR1 heterodimer complexes. Expression of miRNAs is globally inhibited in ADAR1-null mouse embryos, which, in turn, alters expression of their target genes and may contribute to their embryonic lethal phenotype.

Target international normalized ratio values for preventing thromboembolic and hemorrhagic events in Japanese patients with non-valvular atrial fibrillation: results of the J-RHYTHM Registry.

BACKGROUND: Target anticoagulation levels for warfarin in Japanese patients with non-valvular atrial fibrillation (NVAF) are unclear. METHODS AND RESULTS: Of 7,527 patients with NVAF, 1,002 did not receive warfarin (non-warfarin group), and the remaining patients receiving warfarin were divided into 5 groups based on their baseline international normalized ratio (INR) of prothrombin time (≤1.59, 1.6-1.99, 2.0-2.59, 2.6-2.99, and ≥3.0). Patients were followed-up prospectively for 2 years. Primary endpoints were thromboembolic events (cerebral infarction, transient ischemic attack, and systemic embolism), and major hemorrhage requiring hospital admission. During the follow-up period, thromboembolic events occurred in 3.0% of non-warfarin group, but at lower frequencies in the warfarin groups (2.0, 1.3, 1.5, 0.6, and 1.8%/2 years for INR values of ≤1.59, 1.6-1.99, 2.0-2.59, 2.6-2.99, and ≥3.0, respectively; P=0.0059). Major hemorrhage occurred more frequently in warfarin groups (1.5, 1.8, 2.4, 3.3, and 4.1% for INR values ≤1.59, 1.6-1.99, 2.0-2.59, 2.6-2.99, and ≥3.0, respectively; P=0.0041) than in non-warfarin group (0.8%/2 years). These trends were maintained when the analyses were confined to patients aged ≥70 years. CONCLUSIONS: An INR of 1.6-2.6 is safe and effective at preventing thromboembolic events in patients with NVAF, particularly patients aged ≥70 years. An INR of 2.6-2.99 is also effective, but associated with a slightly increased risk in major hemorrhage. (UMIN Clinical Trials Registry UMIN000001569)

Organization of atrial fibrillation using a pure sodium channel blocker: Implications of rotor ablation therapy.

Background: Rotors are the source of atrial fibrillation (AF). However, the ablation of rotors for persistent AF is challenging. The purpose of this study was to identify the dominant rotor by accelerating the organization of AF using a sodium channel blocker and detecting the rotor's preferential area that governs AF. Methods: Overall, 30 consecutive patients with persistent AF who underwent pulmonary vein isolation and still sustained AF were enrolled. Pilsicainide 50 mg was administered. An online real-time phase mapping system (ExTRa Mapping™) was used to identify the meandering rotors and multiple wavelets in 11 left atrial segments. The time ratio of non-passive activation (%NP) was evaluated as the frequency of rotor activity in each segment. Results: Conduction velocity became slower-from 0.46 ± 0.14 to 0.35 ± 0.14 mm/ms (p = .004)-and the rotational period of the rotor was significantly prolonged-156 ± 21 to 193 ± 28 ms/cycle (p < .001). AF cycle length was prolonged from 169 ± 19 to 223 ± 29 ms (p < .001). A decrease in %NP was observed in seven segments. Additionally, 14 patients had at least one complete passive activation area. Of them, the use of high %NP area ablation resulted in atrial tachycardia and sinus rhythm in two patients each. Conclusions: A sodium channel blocker organized persistent AF. In selective patients with a wide organized area, high %NP area ablation could convert AF into atrial tachycardia or terminate AF.

Inosine cyanoethylation identifies A-to-I RNA editing sites in the human transcriptome.

Adenosine-to-inosine (A-to-I) RNA editing is a post-transcriptional processing event involved in diversifying the transcriptome responsible for various biological processes. Although bioinformatic approaches have predicted a number of A-to-I editing sites in cDNAs, the human transcriptome is thought to still harbor large numbers of as-yet-unknown editing sites. Exploring new editing sites requires a biochemical method to accurately identify inosines on RNA strands. We here describe a chemical method to identify inosines, called inosine chemical erasing (ICE), that is based on cyanoethylation combined with reverse transcription. We carried out a large-scale verification of the ICE method focusing on 642 regions in human cDNA and identified 5,072 editing sites, including 4,395 new sites. Functional study revealed that A-to-I intronic editing in the SARS gene mediated by ADAR1 is involved in preventing aberrant exonization of Alu sequence into mature mRNA.

ADAR1 downregulation by autophagy drives senescence independently of RNA editing by enhancing p16INK4a levels.

Cellular senescence plays a causal role in ageing and, in mice, depletion of p16INK4a-expressing senescent cells delays ageing-associated disorders1,2. Adenosine deaminases acting on RNA (ADARs) are RNA-editing enzymes that are also implicated as important regulators of human ageing, and ADAR inactivation causes age-associated pathologies such as neurodegeneration in model organisms3,4. However, the role, if any, of ADARs in cellular senescence is unknown. Here we show that ADAR1 is post-transcriptionally downregulated by autophagic degradation to promote senescence through p16INK4a upregulation. The ADAR1 downregulation is sufficient to drive senescence in both in vitro and in vivo models. Senescence induced by ADAR1 downregulation is p16INK4a-dependent and independent of its RNA-editing function. Mechanistically, ADAR1 promotes SIRT1 expression by affecting its RNA stability through HuR, an RNA-binding protein that increases the half-life and steady-state levels of its target mRNAs. SIRT1 in turn antagonizes translation of mRNA encoding p16INK4a. Hence, downregulation of ADAR1 and SIRT1 mediates p16INK4a upregulation by enhancing its mRNA translation. Finally, Adar1 is downregulated during ageing of mouse tissues such as brain, ovary and intestine, and Adar1 expression correlates with Sirt1 expression in these tissues in mice. Together, our study reveals an RNA-editing-independent role for ADAR1 in the regulation of senescence by post-transcriptionally controlling p16INK4a expression.

Randomized trial of angiotensin II-receptor blocker vs. dihydropiridine calcium channel blocker in the treatment of paroxysmal atrial fibrillation with hypertension (J-RHYTHM II study).

AIMS: Atrial fibrillation (AF) is a common arrhythmia frequently associated with hypertension. This study was designed to test the hypothesis that lowering blood pressure by angiotensin II-receptor blockers (ARB) has more beneficial effects than by conventional calcium channel blockers (CCB) on the frequency of paroxysmal AF with hypertension. METHODS AND RESULTS: The Japanese Rhythm Management Trial II for Atrial Fibrillation (J-RHYTHM II study) is an open-label randomized comparison between an ARB (candesartan) and a CCB (amlodipine) in the treatment of paroxysmal AF associated with hypertension. Using daily transtelephonic monitoring, we examined asymptomatic and symptomatic paroxysmal AF episodes during a maximum 1 year treatment. The primary endpoint was the difference in AF frequency between the pre-treatment period and the final month of the follow-up. The secondary endpoints included cardiovascular events, development of persistent AF, left atrial dimension, and quality-of-life (QOL). The study enrolled 318 patients (66 years, male/female 219/99, 158 in the ARB group and 160 in the CCB group) treated at 48 sites throughout Japan. At baseline, the frequency of AF episodes (days/month) was 3.8 ± 5.0 in the ARB group vs. 4.8 ± 6.3 in the CCB group (not significant). During the follow-up, blood pressure was significantly lower in the CCB group than in the ARB group (P < 0.001). The AF frequency decreased similarly in both groups, and there was no significant difference in the primary endpoint between the two groups. There were no significant differences between the two groups in the development of persistent AF, changes in left atrial dimension, occurrence of cardiovascular events, or changes in QOL. CONCLUSIONS: In patients with paroxysmal AF and hypertension, treatment of hypertension by candesartan did not have an advantage over amlodipine in the reduction in the frequency of paroxysmal AF (umin CTR C000000427).

Discovering A-to-I RNA Editing Through Chemical Methodology "ICE-seq".

RNA editing of adenosines to inosines contributes to a wide range of biological processes by regulating gene expression post-transcriptionally. To understand the effect, accurate mapping of inosines is necessary. The most conventional method to identify an editing site is to compare the cDNA sequence with its corresponding genomic sequence. However, this method has a high false discovery rate because guanosine signals, due to experimental errors or noise in the obtained sequences, contaminate genuine inosine signals detected as guanosine. To ensure high accuracy, we developed the Inosine Chemical Erasing (ICE) method to accurately and biochemically identify inosines in RNA strands utilizing inosine cyanoethylation and reverse transcription-PCR. Furthermore, we applied this technique to next-generation sequencing technology, called ICE-seq, to conduct an unbiased genome-wide screening of A-to-I editing sites in the transcriptome.