EEG1, a putative transporter expressed during epithelial organogenesis: comparison with embryonic transporter expression during nephrogenesis

A screen for genes differentially regulated in a model of kidney developmen t identified the novel gene embryonic epithelia gene 1 (EEG1). EEG1 exists as two transcripts of 2.4 and 3.5 kb that are most highly expressed at embr yonic day 7 and later in the fetal liver, lung, placenta, and kidney. The E EG1 gene is composed of 14 exons spanning a 20-kb region at human chromosom e 11p12 and the syntenic region of mouse chromosome 2. Six EEG1 exons have previously been assigned to a longer isoform of eosinophil major basic prot ein termed proteoglycan 2. Another gene distantly related to EEG1, POV1/PB3 9, is located 88 kb upstream from the EEG1 gene on chromosome 11. Temporal expression of 65 members of the solute carrier (SLC)-class of transport pro teins was followed during kidney development using DNA arrays. POV-1 and EE G1, like glucose transporters, displayed very early maximal gene expression . In contrast, other SLC genes, such as organic anion and cation transporte rs, amino acid permeases, and nucleoside transporters, had maximal expressi on later in development. Thus, although the bulk of transporters are expres sed late in kidney development, a fraction are expressed near the onset of nephrogenesis. The data raise the possibility that EEG1 and POV1 may define a new family of transport proteins involved in the transport of nutrients or metabolites in rapidly growing and/or developing tissues.