Sorting nexin-14, a gene expressed in motoneurons trapped by an in vitro preselection method

A gene-trap strategy was set up in embryonic stem (ES) cells with the aim o f trapping genes expressed in restricted neuronal lineages. The vector used trap genes irrespective of their activity in undifferentiated totipotent E S cells. Clones were subjected individually to differentiation in a system in which ES cells differentiated into neurons. Two ES clones in which the t rapped gene was expressed in ES-derived neurons were studied in detail. The corresponding cDNAs were cloned, sequenced, and analysed by in situ hybrid isation on wild-type embryo sections. Both genes are expressed in the nervo us system. One gene, YR-23, encodes a large intracellular protein of unknow n function. The second clone, YR-14, represents a sorting nexin (SNX14) gen e whose expression in vivo coincides with that of LIM-homeodomain Islet-1 i n several tissues. Sorting nexins are proteins associated with the endoplas mic reticulum. (ER) and may play a role in receptor trafficking. Gene trapp ing followed by screening based on in vitro preselection of differentiated ES recombinant clones, therefore, has the potential to identify integration events in subsets of genes before generation of mouse mutants. (C) 2001 Wi ley-Liss, Inc.