Characterization of histone lysine-specific demethylase in relation to thyroid hormone-regulated anuran metamorphosis

The thyroid hormone receptor (THR) is a member of the nuclear transcription factor and plays a central role in regulating anuran metamorphosis. Previous studies with mammalian cells have suggested that THR is involved in chromatin remodeling through histone methylation. In the present study, we cloned cDNA of lysine-specific demethylase gene, xLSD1, from Xenopus laevis and examined its expression in relation to metamorphosis. Overexpression of xLSD1 in A6 cells, a Xenopus laevis cell line, resulted in the decrease of methylation status of lysine residues of histone H3, indicating that the protein of cloned xLSD1 was functionally active. The expression of LSD1 at mRNA levels was up-regulated in the body skin and the intestine during natural and thyroid hormone-induced metamorphosis. Larval epidermal basal cells and intestinal epithelial cells at the premetamorphic stage were identified as the xLSD1-expressing cells. At the metamorphic climax stage the progenitor cells of adult epidermal basal cells also expressed xLSD1, whereas those of the adult intestinal epithelial cells did not. We propose that LSD1 participates in the regulation of metamorphosis through THR- or another transcriptional factor-induced chromatin remodeling.