Two zebrafish homologues of the Drosophila neurogenic gene groucho and their pattern of transcription during early embryogenesis

GROUCHO is a Drosophila nuclear protein with structural similarity to the transcriptional repressor TUP1. Drosophila GROUCHO forms complexes with bHLH proteins of the HAIRY-ENHANCER OF SPLIT [-E(SPL)] family, that then act as repressors, for example downstream of the NOTCH Signalling pathway. We describe the isolation and sequence of two zebrafish GROUCHO homologues and the pattern of transcript distribution during embryogenesis. Both GRO1 and GRO2 exhibit all sequence features characteristic of the GROUCHO family and, with 79% sequence similarity at the DNA level, can be considered as orthologues of the human GROUCHO homologue TLE3. RNA in situ hybridization shows a distinct pattern of transcript distribution for both genes during embryogenesis suggestive of their participation in neurogenesis and somitogenesis.