Gene expression changes in injured myocardium of Ciona intestinalis

Ciona intestinalis is an invertebrate animal model system that is well characterized and has many advantages for the study of cardiovascular biology. The regulatory mechanisms of cardiac myocyte proliferation in Ciona are intriguing since Ciona are capable of regeneration throughout their lifespan. To identify important regeneration factors in Ciona, microarray analysis was conducted on RNA from adult Ciona hearts with normal or damaged myocardium using custom Affymetrix GeneChips. After a 24- or 48-hour recovery period, total RNA was isolated from damaged and control hearts. Initial results indicate significant changes in gene expression in hearts damaged by ligation in comparison to cryoinjured or control hearts. Ligation injury shows differential expression of 223 genes as compared to control (fold change >2, p<0.01, Student’s t-test) with limited false discovery (5.8%). Among these 223 genes, 117 have known human orthologs of which 68 were up-regulated and 49 were down-regulated. Notably, FGF 9/16/20 and Ras were significantly upregulated in injured hearts. Histological analyses of injured myocardium were conducted in parallel to the microarray study. Taken together, these studies will coordinate differences in gene expression to cellular changes in the regenerative myocardium of Ciona, which will help to elucidate the regulatory mechanisms of cardiac myocyte proliferation across chordates. Samples were prepared from Ciona intestinalis adult (7-12 cm) control hearts (exposed but not ligated) or injured hearts (ligated or cryo injury) at 24h or 48h following treatment with two biological replicates per sample type. A minimum of 4 hearts per group was done for each experiment. Microarray profiling was performed using the Affymetrix Ciona intestinalis custom-designed array (CINT06a520380F; GEO platform GPL15657).