Yi-Hsien Su

Development of animal body plans are controlled by large networks of regulatory genes. Gene regulatory networks (GRNs) describe signaling pathways leading to the activation of DNA-recognizing regulatory proteins (transcription factors) and the interactions between the transcription factors and the modular DNA sequence elements that control spatial and temporal expression of regulatory genes. A given set of regulatory genes expressed in certain cells at a certain time during development specifies cell differentiation, organogenesis, and body plan formation.
Sea urchins have been a research model in developmental biology for over a century. They are highly fecund, producing millions of gametes each year. Due to the remarkable usefulness of the echinoderm embryo for modern molecular, cellular and evolutionary biology studies, the genome of the sea urchin Strongylocentrotus purpuratus was sequenced in 2006. The current gene regulatory network (GRN) of the sea urchin Strongylocentrotus purpuratus embryo describes the specification of the endomesodermal territories. However, the specification of the adjacent ectodermal territories of the embryo has been far less explored. Recently, a large-scale gene regulatory network analysis was conducted and an ectoderm specification GRN model was proposed. In the ectoderm GRN, two TGF-ß superfamily members, Nodal and BMP2/4, play key roles in the specification of the oral and aboral ectoderm, respectively. The deduced GRN model provides the first peek at the overall picture of oral and aboral ectoderm specification in the sea urchin embryo and also raises several unanswered questions.
My lab is interested in the roles of Nodal and BMP2/4 in specifying the development of oral and aboral ectoderm in the sea urchin embryo. We are also interested in comparative studies on Nodal in other animals. We use local Taiwanese animals, a hemichordate and a small abalone, to study the function of Nodal in their development. The overall goal of these studies is not only to use a traditional model system, the sea urchin, to investigate important questions that have emerged from GRN analysis, but to also use local animal species with crucial phylogenetic positions to answer fundamental questions. These studies will complement the current ectoderm GRN in the sea urchin embryo, provide further information on how TGF family proteins pattern a specific cell lineage, and shed light on the changes of Nodal function during evolution.

Selected Publications

1. Su Y.H. (2009) Gene regulatory networks for ectoderm specification in sea urchin embryos. Biochimica et Biophysica Acta - Gene Regulatory Mechanisms, 1789, 261-267.
2. Su Y.H., Li E., Geiss G.K., Longabaugh W.J., Kramer A, Davidson E.H. (2009) A perturbation model of the gene regulatory network for oral and aboral ectoderm specification in the sea urchin embryo. Developmental Biology, 329, 410-421.
3. Churamani, D., Boulware, M.J., Geach, T.J., Martin, A.C., Moy, G.W., Su, Y.H., Vacquier, V.D., Marchant, J.S., Dale, L., Patel, S. (2007) Molecular characterization of a novel intracellular ADP-ribosyl cyclase. PLoS One, 2(8): e797.
4. Nam J, Su Y.H., Lee P.Y., Robertson A.J., Coffman J.A., Davidson E.H. (2007) Cis-regulatory control of the nodal gene, initiator of the sea urchin oral ectoderm gene network. Developmental Biology, 306, 860-869.
5. Roux, M.M., Townley, I.K., Raisch, M., Reade, A., Bradham, C., Humphreys, G., Gunaratne, H.J., Killian, C.E., Moy, G., Su, Y.H., Ettensohn, C.A., Wilt, F., Vacquier, V.D., Burke, R.D., Wessel, G., and Foltz, K.R. (2006) A functional genomic and proteomic perspective of sea urchin calcium signaling and egg activation. Developmental Biology, 300, 416-433.
6. Sodergren, E., et al., (2006) The genome of the sea urchin Strongylocentrotus purpuratus. Science, 314, 941-952.
7. Su, Y.H. and Vacquier, V.D. (2006) Cyclic GMP-specific phosphodiesterase-5 regulates motility of sea urchin spermatozoa. Molecular Biology of the Cell, 17, 114-121.
8. Su, Y.H.*, Chen, S.H., Zhou, H., and Vacquier, V.D. (2005) Tandem mass spectrometry identifies proteins phosphorylated by cyclic AMP-dependent protein kinase when sea urchin sperm undergo the acrosome reaction. Developmental Biology, 285, 116-125 (*corresponding author).
9. Su, Y.H. and Vacquier, V.D. (2002) A flagellar K+-dependent Na+/Ca2+ exchanger keeps Ca2+ low in sea urchin spermatozoa. Proceedings of the National Academy