In The Atrial Fibrillation Cell Model, ATBF1 And PIAS3 Synergistically Activate The STAT3 Signaling Pathway

Background:Atrial fibrillation (AF) is progressive and is the most common clinical arrhythmia. It is associated with inflammatory changes characterized by signal transducer and activator of transcription3(STAT3) signaling. A zinc finger homeobox3(ZFHX3, also named AT-motif binding factor1, ATBF1) gene variant has been found in patients with AF. However, the mechanism by which the ATBF1leads to inflammation in AF remains unknown.Objective:The aim of this study was to investigate whether tachypacing induces a decrease in ATBF1expression and then activates STAT3signaling via protein inhibitor of activated STAT3(PIAS3).Methods:Atrial (HL-1myocytes) cells were cultured in the presence of rapid electrical stimulations. The synthesized ATBFland PIAS3-specific siRNAs and the plasmid of ATBF1vector were transfected into HL-1cells by using LipofectamineTM2000. The protein level of ATBF1, PIAS3and STAT3were detected by Western Blotting. Co-immunoprecipitation (co-IP) was performed to investigate the possibility of direct binding of ATBF1, PIAS3, p-STAT3and STAT3in tachypaced HL-1cells and control cells. EMSA was performed to further examine the DNA-binding ability of activated STAT3in pacing-induced HL-1cells.Results:The cell model for atrial fibrillation was constructed successfully which was confirmed by shortening of action potential duration and by increasing of Caspase-3. In tachypaced HL-1cells, ATBF1and PIAS3protein levels were decreased, while the level of phosphorylated STAT3(p-STAT3) was highly up-regulated compared with that of total STAT3. Knockdown of ATBF1enhanced this trend, while the overexpression of ATBF1had the opposite effect. A binary complex of ATBF1and PIAS3was formed and then the DNA-binding ability of activated STAT3was enhanced in tachypaced HL-1cells.Conclusions:We establish the cell model line for atrial fibrillation successfully. Tachypacing decreased ATBF1, leading to enhanced STAT3DNA-binding activity due to the reduced formation of a binary complex of ATBF1and PIAS3.