Purpose: A cell-type specific genetic regulatory unit is very useful to obtain a pure cell-population for tissue engineering. At present, a spatiotemporal atrial cardiomyocyte specific gene has not been found yet. This study aims to find a genuine atria-specific gene and utilize an atria specific genetic regulatory unit.
Methods: To find a novel atrial specific gene, we conducted comparable gene array analysis between purified neonatal rat atrial and ventricular cardiomyocytes. Then, we verified the atrial specific expression of a novel gene by quantitative PCR and lacZ knock-in mouse. Next, to obtain atria specific regulatory unit, we analyzed the genomic structure bioinformatically, and investigated transcriptional regulatory functions of candidate-regions by GFP expression vectors bearing suspected sequences.
Results: We found a candidate gene that had good contrast between atrium and ventricle by gene array analysis. The novel gene was atrial specific among the fourteen major organs and tissues from embryonic day 14 through to adult in qPCR. This specificity was also confirmed by lacZ knock-in mouse assay. Bioinformatics suggested some possible regulatory regions in introns besides the 5' non-coding region. GFP expression vectors containing the sole 5' region showed "cardiomyocyte-specific expression". Very interestingly, further addition of an intronic candidate region showed restricted expression of GFP only in atrial cardiomyocytes, suggesting that a possible regulatory region may work as non-atrial repressor.
Conclusions: We identified a novel and genuine atrial specific marker gene, and extracted its transcriptional regulatory units. Our result may serve an atria specific genetic regulatory unit which will be very useful to obtain a pure cell-population for tissue engineering.