The zebrafish has proven to be a powerful vertebrate model system for the genetic analysis of developmental pathways and is only beginning to be exploited as a model for human disease and clinical research. During the past years zebrafish has served as an excellent model for understanding normal development and birth defects based on its powerful genetics and exquisite embryology. Zebrafish allows the powerful combination of loss-of-function and gain-of-function analyses to combine cell and molecular biology as well forward and reverse genetics. Recently, research with zebrafish has extended to model human diseases and to analyze the formation and functions of cell populations within organs for organ regenertaion and stem cell biology. This work has generated new human disease models (including human cancer) and has begun to establish therapeutic possibilities, including genes that modify disease states and chemicals that rescue organs from disease.

Several reasons recommend this vertebrate as an optimal model system for cardiovascular studies. Zebrafish embryos are not completely dependent on a functional cardiovascular system to continue to survive and develop, because embryos receive enough oxygen by passive diffusion, thereby allowing a detailed analysis of animals with severe vascular defects. Further, the striking transparency of the embryos facilitates morphological observation of internal organs in vivo under a simple stereomicroscope, also at the single-cell level.

The cardiovascular system is the first organ to form and function during embryonic development. Its correct development is essential for the proper formation of vertebrate embryos as well as for adulthood. Using a set of new cellular, molecular, and genetic approaches as well as advanced microscopy techniques, we propose to elucidate how endothelial and mural cells cooperate to shape the cardiovascular system and regulate vascular maturation and myogenesis. The long-term goal is to provide additional molecular entry points to further investigate EC maturation and MC development/differentiation in normal and pathological conditions using the zebrafish vertebrate system. We are currently investigating three different topics using the vertebrate model of zebrafish.

1) New pathways involved in survival and apoptosis of endothelial cells during angiogenesis and blood vessels homeostasis (Santoro et a.l, 2007);

2) Identification of new genes involved in angiogenesis and vascular maturation (Jin et al., 2007);

3) Role of vascular mural cells (pericytes and vascular smooth muscle cells) during cardiovascular development in normal and pathological conditions (Santoro et al., 2009).

We select the zebrafish system as a model to investigate cardiovascular development and associated diseases, like heart regeneration, tumor angiogenesis, and atherosclerosis.

Santoro, M.M., Pesce, G., and Stainier, D.Y. (2009). Cellular and developmental characterization of vascular mural cells in zebrafish. Mech Dev, accepted.

Fish, J.E., Santoro, M.M., Morton, S.U., Yu, S., Yeh, R.F., Wythe, J.D., Ivey, K.N., Bruneau, B.G., Stainier, D.Y., and Srivastava, D. (2008). miR-126 regulates angiogenic signaling and vascular integrity. Dev Cell 15, 272-284.

Gyrd-Hansen, M., Darding, M., Miasari, M., Santoro, M.M., Zender, L., Xue, W., Tenev, T., da Fonseca, P.C., Zvelebil, M., Bujnicki, J.M., et al. (2008). IAPs contain an evolutionarily conserved ubiquitin-binding domain that regulates NF-kappaB as well as cell survival and oncogenesis. Nat Cell Biol 10, 1309-1317.

Jin, S.W., Herzog, W., Santoro, M.M., Mitchell, T.S., Frantsve, J., Jungblut, B., Beis, D., Scott, I.C., D'Amico, L.A., Ober, E.A., et al. (2007). A transgene-assisted genetic screen identifies essential regulators of vascular development in vertebrate embryos. Dev Biol 307, 29-42.

Chianale, F., Cutrupi, S., Rainero, E., Baldanzi, G., Porporato, P.E., Traini, S., Filigheddu, N., Gnocchi, V.F., Santoro, M.M., Parolini, O., et al. (2007). Diacylglycerol kinase-alpha mediates hepatocyte growth factor-induced epithelial cell scatter by regulating Rac activation and membrane ruffling. Mol Biol Cell 18, 4859-4871.

Santoro, M.M., Samuel, T., Mitchell, T., Reed, J.C., and Stainier, D.Y. (2007). Birc2 (cIap1) regulates endothelial cell integrity and blood vessel homeostasis. Nat Genet. 39, 1397 – 1402.

Germano, S., Barberis, D., Santoro, M.M., Penengo, L., Citri, A., Yarden, Y., and Gaudino, G. (2006). Geldanamycins trigger a novel Ron degradative pathway, hampering oncogenic signaling. J Biol Chem 281, 21710-21719.

Santoro, M.M., and Gaudino, G. (2005). Cellular and molecular facets of keratinocyte reepithelization during wound healing. Exp Cell Res 304, 274-286.

Santoro, M.M. (2003). New Findings In Growth Factor Receptors And Integrins
Cross Talk. Recent Research Developments In Molecular And Cellular Biology,
Vol. 3, Part-II, Page 661-675.

Santoro, M.M., Gaudino, G., and Marchisio, P.C. (2003a). The MSP receptor regulates alpha6beta4 and alpha3beta1 integrins via 14-3-3 proteins in keratinocyte migration. Dev Cell 5, 257-271.

Santoro, M.M., Gaudino, G., and Villa-Moruzzi, E. (2003b). Protein phosphatase 1 binds to phospho-Ser-1394 of the macrophage-stimulating protein receptor. Biochem J 376, 587-594.

Brunelleschi, S., Penengo, L., Santoro, M.M., and Gaudino, G. (2002). Receptor tyrosine kinases as target for anti-cancer therapy. Curr Pharm Des 8, 1959-1972.

Santoro, M.M., Penengo, L., Orecchia, S., Cilli, M., and Gaudino, G. (2000). The Ron oncogenic activity induced by the MEN2B-like substitution overcomes the requirement for the multifunctional docking site. Oncogene 19, 5208-5211.

Santoro, M.M., Penengo, L., Minetto, M., Orecchia, S., Cilli, M., and Gaudino, G. (1998). Point mutations in the tyrosine kinase domain release the oncogenic and metastatic potential of the Ron receptor. Oncogene 17, 741-749.

Santoro M.M. and Gaudino G. (1997). Motogenic Growth Factors: HGF/SF And MSP. Minerva Biotecnologica 9, 85-92.

Santoro, M.M., and Gaudino, G. The Constitutive Activation Of Met, Ron, Sea
Genes Induces Different Biological Responses. (1997). In "Interacting Protein Domains" Nato-Asi Series, Subseries H "Cell Biology", Vol. 102 Ed. By L. Heilmeyer, Pp 207-212, Springer-Verlag Heidelberg.

Collesi, C., Santoro, M.M., Gaudino, G., and Comoglio, P.M. (1996a). A splicing variant of the RON transcript induces constitutive tyrosine kinase activity and an invasive phenotype. Mol Cell Biol 16, 5518-5526.

Santoro, M.M., Collesi, C., Grisendi, S., Gaudino, G., and Comoglio, P.M. (1996b). Constitutive activation of the RON gene promotes invasive growth but not transformation. Mol Cell Biol 16, 7072-7083.

Gaudino, G., Follenzi, A., Naldini, L., Collesi, C., Santoro, M., Gallo, K.A., Godowski, P.J., and Comoglio, P.M. (1994). RON is a heterodimeric tyrosine kinase receptor activated by the HGF homologue MSP. EMBO J 13, 3524-3532.