Molecular bases of the body-plan in vertebrate

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Hox genes are expressed in the limb muscle precursor in position specific manner by interacting with the limb mesenchymal cells and the expression profile exhibited closed relationship with following muscle mass splitting pattern Six2 expression in the tendon precursor cells was under the control of the signals from the limb cartilage and the ectoderm. In addition Hox protein modulated the sensitivity for these signals. (A.K.) Transcription factor SOX2/SOX3 and PAX6 were expressed in the lens placode during development and functioned through interacting with enhancer DC5 of ヲト-crystalline gene. These transcription factors induced lens placode differentiation in a combinational manner when ectopically expressed in the embryos. (H.K.)We examined the process of the establishment of vertebrate body plan through the analysis of the function and the regulation of the expression of the ascidian homeobox genes. We found that Otx stimulates differentiation toward anterior nervous system and controls the expression of the downstream genes as the transcriptional activator. (H.S.) Mouse novel gene mmabl, a ortholog of nematode mab21, and its homolog mmab2 were isolated as the downstream target gene of Hoxc-4. We produced knockout mice of these genes and found that the expression of mmab1 in the sternum was under the control of Hoxc-4.(N.T.) STEF, a mouse homolog of Drosophila still life, is a Rac specific guanine nucleotide exchanging factor. STEF was involved in the migration, axonal extension and synapse formation through activation of Rac followed by the conformational change of the cytoskeleton system. (Y.N.) By Drosophila mutational analysis, we found the gene determining the body size that encodes a novel and evolutionary conserved protein. Genetic interaction experiment revealed that the protein products functioned upstream of E2A in the Insulin receptor system that control cellular growth. (Y.N.)