A targeting vector was designed to insert an internal ribosome entry site (IRES), a Cre recombinase sequence, a polyA sequence, and an frt-flanked neo cassette into the 3' untranslated region (after the translational termination site) of the somatostatin locus (Sst). This construct was electroporated into C57BL/6;129 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. Chimeric males were bred with Actin-FLPe females (on a C57BL/6 congenic background) to achieve germline transmission and to remove the neo selection cassette.
This mutation results in a dosage-dependent knock-down of endogenous Sst expression J:279254 .