Wnt and TGF-beta signaling in the ctenophore, Mnemiopsis leidyi

Meeting Abstract

P1.76  Monday, Jan. 4  Wnt and TGF-beta signaling in the ctenophore, Mnemiopsis leidyi PANG, K.*; RYAN, J.F.; MULLIKIN, J.C.; BAXEVANIS, A.D.; MARTINDALE, M.Q.; Univ. of Hawaii at Manoa; National Institutes of Health, NHGRI; National Institutes of Health, NHGRI; National Institutes of Health, NHGRI; Univ. of Hawaii at Manoa kpang@hawaii.edu

Of all the non-bilaterian animal groups, the gene content and complexity of ctenophores is the least known. While some information is known about transcription factors belonging to the T-box, Sox, and Homeobox families, nothing is known about the developmental signaling pathways. Cell-signaling pathways play important roles in bilaterian axis specification and development. Recent studies have shown that the Wnt/Beta-catenin and TGF-beta family evolved early in animal evolution, as evidenced their presence in the genomes of cnidarians, sponges, and the placozoan. Studies on their expression patterns and function suggest they play integral roles in early axis specification in both cnidarians and sponges. Unlike the other non-bilaterians, ctenophores display a highly stereotyped cleavage program, with cell fates determined early in development. Experimental manipulation studies have shown that the site of first cleavage sets up the major body axis of ctenophores, the oral-aboral axis. We sought to understand the roles of Wnt and TGF-beta signaling during ctenophore development to determine if they are involved in early axis specification. We utilized next-generation sequencing technologies and are in the process of sequencing and assembling the genome of the lobate ctenophore, Mnemiopsis leidyi. All essential components of both Wnt and TGF-beta pathways are present in the genome. We were able to identify and isolate 4 Wnt and 9 TGF-beta ligands and examined their expression pattern during development. All 4 Wnt genes are expressed in discreet regions of the aboral pole late in development, whereas a set of TGF-beta genes are expressed at the onset of gastrulation in discrete regions along the oral-aboral axis.

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