My laboratory studies maternal control of early embryonic development and functions of PP2A in operating signaling pathways.
I. PP2A-dependent reversible protein phosphorylation in controlling signaling pathways
PP2A is one of the most abundantly expressed Ser/Thr protein phosphatases, making up to 0.1% of the total cellular protein in most cells. PP2A is a heterotrimer. The substrate specificity, subcellular localization, and catalytic activity of the holoenzyme are controlled by PP2A regulatory subunits. My laboratory has a long-standing interest in studying B56 regulatory subunits of PP2A. We have been identifying novel substrates of B56-containing PP2As and studying how B56-containing PP2As regulate the functions of their substrates. We are particularly interested in the molecular mechanisms by which B56-containing PP2As regulate the Wnt and Hedgehog pathways.
II. Maternal control of early embryonic development
Following fertilization, the zygotic genome is globally silenced and, for a period of time, embryonic development is controlled by maternal gene products. This global repression is gradually released during the maternal-to-zygotic transition (MZT). After the MZT, embryonic development becomes under the exclusive control of the zygotic genome. During Xenopus development, zygotic genome activation occurs at the mid-blastula stage in the somatic cell lineages. In the germline, however, the zygotic genome remains quiescent till the early neurula stage. Silencing the genome of the primordial germ cells (PGCs) during blastula and gastrula stages is critically important, because it prevents PGCs from responding to signals that specify somatic cell fates, hence it is essential for maintaining the totipotency of PGCs. Although this mechanism is highly conserved among vertebrate and invertebrate species, it is largely unclear how the MZT is regulated during the germline development. Currently, we are studying roles of Dead End1 (Dnd1) and other maternal RNA-binding proteins in controlling the MZT during Xenopus germline development.