Quantitative proteomic analysis of the cellular response during cardiac regeneration in the leopard gecko (Eublepharis macularius)

Cardiac regeneration has been characterized in individual species of fish and amphibians, vertebrates whose hearts are comparatively simple in structure, and function at low pressure. Here, we use quantitative proteomics to characterize the cellular response in the heart of the gecko ( Eublepharis macularius ) following injury. Gecko hearts are more complex, and function at higher pressure, than those of fish and amphibians. Hearts were damaged using a cryoprobe and wound sites were sampled at 3-, 14-, 30- and 100-days post injury (dpi). Samples were also taken from sham operated geckos. Overall, 579 proteins were differentially expressed across at least two time points. Importantly, we found increased expression of agrin at 14-dpi, a protein that facilitates cardiomyocyte dedifferentiation. This is the first time that an increase in agrin expression following cardiac injury, has been reported. Gene Ontology (GO) analysis indicates that by 14-dpi there is a decrease in oxidative and glycolytic capacity as well as in sarcomere organization and mitochondrial content. However, by 100-dpi these were all recovered. There were also no GO terms between sham and 100-dpi hearts, suggesting that the cardiac proteome is returning to the pre-injury state. This work indicates that heart regeneration in geckos involves reorganization of cellular pathways associated with mitosis, energy production and contractile function.