Chamber-specific transcriptional responses in atrial fibrillation

Abstract

Histology and immunohistochemistry. Immunohistochemistry was performed on paraffin-embedded sections. Gross heart morphology and collagen content were examined using Masson's trichrome stain (American MasterTech Scientific). Wheat germ agglutinin staining was used to visualize cell membranes and enable quantification of CM cell size. Microelectrode recordings. Investigators were blinded to the sample group allocation during the experiment and analysis of experimental outcome. Mouse hearts were Langendorff perfused and were recorded while in sinus rhythm and when stimulated at 10 Hz (approximately 600 beats per minute). Using glass sharp microelectrodes, single LA CMs were sampled near the epicardial surface. To decrease noise from motion artifacts, blebbistatin (0.2 mg/mL) was used to arrest motion and allow for stable microelectrode recording without requiring the use of floating electrodes. Additional information. All methods related to mouse RT-qPCR (Supplemental Table 14) and RNA-sequencing and analysis are detailed in the Supplemental Methods. Expanded methods for human tissue acquisition, CMN isolation, histology and immunohistochemistry, and microelectrode recordings are also supplied in the Supplemental Methods. RA RNA-sequencing accession number. RA RNA-sequencing data discussed in this manuscript have been deposited in the National Center for Biotechnology Information's (NCBI) Gene Expression Omnibus (GEO) database and are accessible through GSE100244. LA RNA-sequencing accession number. LA RNA-sequencing data discussed in this manuscript have been deposited in NCBI's GEO and are accessible through GSE138253. Human RNA-sequencing accession number. Data have been deposited in NCBI's GEO and are accessible through GSE138252. Statistics. All data are expressed as mean ± SEM. Statistical analyses were performed after assessing for normal distribution using either paired or unpaired Student's 2-tailed t tests for comparison of 2 groups with a Welch's correction. Values of P < 0.05 were considered statistically significant. Study approval. Animal protocols were approved by the Animal Studies Committee at Washington University in St. Louis, and animals were handled in accordance with the NIH's Guide for the Care and Use of Laboratory Animals (National Academies Press, 2011). Protocols involving human tissue acquisition were approved by the Washington University in St. Louis IRB. Informed consent was obtained for all tissue before inclusion in this study. Methods described in this manuscript were performed in accordance with all human research guidelines. Author contributions SLR was responsible for conceptualization of the study. SLR, CEL, JJ, and QG contributed to experimental design. CEL, JJ, QG, TY, and SB conducted experiments, acquired data, and performed data analysis. SCH conducted histology staining. GL contributed to data analysis. CEL, JJ, QG, GL, TY, SCH, DMZ, UG, KT, and BDB contributed to human tissue acquisition. RDN and CPC performed mouse RNA-sequencing and statistical analysis. SL and BZ perfo...

Adding a “Notch” to Cardiovascular Disease Therapeutics: A MicroRNA-Based Approach

“…As demonstrated in Hey2 (+/−) heterozygous knockout mice, in the presence of this SNP, Hey2 affects the normal transmural electrophysiological gradient in the ventricle ( Veerman et al, 2017 ). The link between Notch and arrhythmias has been recently confirmed by a study showing that Notch activation within left atrium cardiomyocytes generates a transcriptomic fingerprint resembling AF and distinct cellular electrophysiologic responses ( Lipovsky et al, 2020 ).…”

Calcium Regulation on the Atrial Regional Difference of Collagen Production Activity in Atrial Fibrogenesis

“…The gene expression of aldose reductase, which is a protein that can activate the PLC signaling pathway and enhance Ca 2+ influx, is more highly expressed in LA than in RA tissues [ 11 , 52 , 53 ]. Moreover, the activation of the Notch signaling pathway was found in the LA but not in the RA in patients with atrial arrhythmia [ 54 ]. Notch activation can upregulate STIM1 expression and activate store-operated Ca 2+ entry [ 55 , 56 ].…”

Molecular Basis of Atrial Fibrillation Initiation and Maintenance

“…The above changes are mostly linked to Ca 2+ -handling abnormalities, yet other pathways are also modulated by non-heritable expression changes. The Notch signaling pathway is dysregulated in an AF-dependent manner in end-stage HF patients, with over a quarter of its downstream transcripts being directly linked to atrial arrhythmias [62]. Several genes from the autonomic signaling cascade, including some phosphodiesterase (PDE) families, also showed pathology specific expression changes in atrial samples from AF patients [63].…”