In a recent study published by researchers from Sun Yat-Sen University, atrial fibrillation (AF) associated microRNAs (miRNAs) were found in the right atrium (RA) and left atrium (LA) from patients with rheumatic mitral valve disease (RMVD). While most studies only focus on the RA; and the potential differences of AF-associated miRNAs between the RA and LA are still unknown, the aim of their study was to perform miRNA expression profile analysis to compare the potential differences of AF-associated miRNAs in the right atrial appendages (RAA) and left atrial appendages (LAA) from RMVD patients. Sample tissues from the RAA and LAA were obtained from 18 RMVD patients (10 with AF) during mitral valve replacement surgery. From these tissues, miRNA expression profiles were created and analyzed using a human LC Sciences miRNA microarray services. Their results were then validated using qRT-PCR analysis for 12 selected miRNAs. Finally, potential targets of 10 validated miRNAs were predicted and their functions and potential pathways were analyzed using the miRFocus database. In RAA, the researchers found 65 AF-associated miRNAs were significantly dysregulated (i.e. 28 miRNAs were up-regulated and 37 were down-regulated). In LAA, the researchers found 42 AF-associated miRNAs were significantly dysregulated (i.e. 22 miRNAs were up-regulated and 20 were down-regulated). Among these AF-associated miRNAs, 23 of them were found in both RAA and LAA, 45 of them were found only in RAA, and 19 of them were found only in LAA. Finally, 10 AF-associated miRNAs validated by qRT-PCR were similarly distributed in RAA and LAA; 3 were found in both RAA and LAA, 5 were found only in RAA, and 2 were found only in LAA. Potential miRNA targets and molecular pathways were identified by the scientists, in addition to different distributions of AF-associated miRNAs in the RAA and LAA from RMVD patients. This may reflect different miRNA mechanisms in AF between the RA and LA. Their findings may provide new insights into the underlying mechanisms of AF in RMVD patients.

 

Heat map showing the miRNAs significantly dysregulated in RAA and LAA tissues.

 

LC Sciences

(A) Heat map showing the expression of dysregulated miRNAs in RAA tissues (AF-RAA vs SR-RAA). (B) Heat map showing the expression of dysregulated miRNAs in LAA tissues (AF-LAA vs SR-LAA).

 

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Reference

Liu H, Qin H, Chen GX, Liang MY, Rong J, Yao JP, Wu ZK. Comparative expression profiles of microRNA in left and right atrial appendages from patients with rheumatic mitral valve disease exhibiting sinus rhythm or atrial fibrillation. (2014) J Transl Med. 12(1):90 [article]