Meeting Abstract

37.1  Jan. 5  Diverse responses with identical genes: Identification of a core set of thyroid hormone-induced genes across tissues during frog metamorphosis BUCHHOLZ, D.R.; Dep’t of Biological Sciences, University of Cincinnati buchhodr@ucmail.uc.edu

Thyroid hormone plays a central role in vertebrate post-embryonic development. Amphibian metamorphosis provides a unique opportunity to examine thyroid hormone-dependent developmental changes, which include major physiological and morphological changes in tadpoles, such as tail resoprtion, generation of limbs, remodeling of brain and intestine. To establish a global molecular framework for understanding morphological changes induced by thyroid hormone, we identified a set of gene expression profiles via microarray analysis during the intestinal remodeling process controlled thyroid hormone. Samples were obtained from Xenopus laevis tadpole intestines at a premetamorphic stage (stage 53) after 0, 1, 3, and 6 days of 10 nM triiodothyronine (T3) treatment, which induces successive cell death and proliferation essential for this intestinal remodeling process. Using a set of 21,807 60-mer oligonucleotide probes representing > 98% of the Unigene clusters, we found that 1,997 genes were differentially regulated by at least 1.5 fold during this remodeling process and were clustered into four temporal expression profiles; transiently up- or downregulated and late up- or downregulated. Gene Ontology categories significantly associated with these clusters were proteolysis, cell cycle, development and transcription, and electron transport and metabolism, respectively. Furthermore, meta-analysis with T3-regulated genes during the metamorphic changes in brain, hind limb, and tail indicated that more than 70% of T3-regulated genes are tissue-specific. On the other hand, a core set of upregulated genes, most previously unknown to be T3-regulated, were identified, and are composed mainly of genes involved in transcription and cell signaling.