Characterization of p53/p63/p73 and Myc expressions during embryogenesis of the sea urchin.

Background: Some marine invertebrate organisms are considered not to develop tumors due to unknown mechanisms. To gain an initial insight into how tumor‐related genes may be expressed and function during marine invertebrate development, we here leverage sea urchin embryos as a model system and characterize the expressions of Myc and p53/p63/p73 which are reported to function synergistically in mammalian models as an oncogene and tumor suppressor, respectively. Results: During sea urchin embryogenesis, a combo gene of p53/p63/p73 is found to be maternally loaded and decrease after fertilization both in transcript and protein, while Myc transcript and protein are zygotically expressed. p53/p63/p73 and Myc proteins are observed in the cytoplasm and nucleus of every blastomere, respectively, throughout embryogenesis. Both p53/p63/p73 and Myc overexpression results in compromised development with increased DNA damage after the blastula stage. p53/p63/p73 increases the expression of parp1, a DNA repair/cell death marker gene, and suppresses endomesoderm gene expressions. In contrast, Myc does not alter the expression of specification genes or oncogenes yet induces disorganized morphology. Conclusions: p53/p63/p73 appears to be important for controlling cell differentiation, while Myc induces disorganized morphology yet not through conventional oncogene regulations or apoptotic pathways during embryogenesis of the sea urchin. Key Findings: p53/p63/p73 protein is maternally loaded, while Myc protein expression starts zygotically.p53/p63/p73 and Myc proteins are localized in the cytoplasm and nucleus of all blastomeres, respectively, during early embryogenesis.Overexpression of p53/p63/p73 and Myc increases their nuclear localization and DNA damage in the resultant embryos.p53/p63/p73 appears to suppress gene expressions for cell specification differentiation, while Myc has no impact on specification genes yet causes disorganized morphology and embryonic death. [ABSTRACT FROM AUTHOR]