Cloning and tissue-specific gene expression studies with Dlxin-1, a newly identified transcriptional activator.

Dlxin-1, a unique member of the necdin/melanoma associated antigen gene (MAGE) family, is a novel protein that binds Dlxin-5 and regulates its transcriptional function. We have cloned the homology region between Dlxin-1 and necdin from mouse melanoma cells. Here we report the expression cloning, characterization, and detailed tissue-specific expression studies of Dlxin-1. A unique expression pattern of Dlxin-1 emerged from the work wherein strong expression of a 3.2-Kb transcript was observed in mouse brain and embryos. Amongst the representative established cell lines of different tumor categories studied the presence of transcript was detected only in sarcomas and neuroectodermal tumors. Characteristically, lymphomas, leukaemias, adenocarcinomas, and carcinomas did not express Dlxin-1. Also, we observed a growth suppression on ectopic expression of this cDNA possibly due to the close homology shared with necdin, a neuron-specific growth suppressor. The extensive homology of our Dlxin-1 clone to necdin makes it an attractive system to understand the importance of the necdin/MAGE family of molecules in cell cycle regulation.