Targeted disruption of Zfp36l2. (A) Schematic representation of the normal genomic locus for Zfp36l2 as well as the targeting vector and resulting disrupted allele generated by homologous recombination. The 2 exons are represented by gray boxes. The translational start site is indicated by the arrow (under Sa). Genomic 5′ and 3′ probes, located outside the targeting vector, are represented by stippled boxes. The targeting vector contained a neomycin resistance marker cassette (PGKNeo), causing the deletion of a large portion of the second exon. A diphtheria toxin resistance element was also inserted into the targeting vector (PGKDTA). The black lines above the endogenous and targeted genes represent the expected fragment length after digestion with EcoRV and SstI or EcoRI and hybridization with the 5′ probe or 3′ probe, respectively. PCR primers used to detect homologous recombination (F1, R1) as well as for genotyping offspring (F1, F2, and R2) are indicated by the arrows beneath the endogenous and targeted genes. Primers F3, R3, F4, and R4 were used to generate an exon one fragment (F3, R3) or a 3′UTR fragment (F4, R4) used as hybridization probes for Northern blots. Abbreviations for restriction enzyme sites are as follows: A indicates Asp718; C, Csp45I; E, EcoRI; EV, EcoRV; H, HindIII; N, NotI; Sa, SalI; S, SstI; St; stop codon; X, XbaI. (B) Southern blot analysis of EcoRV/SstI (5′ genomic probe) and EcoRI (3′ genomic probe)–digested genomic DNA from WT and homologously recombined (HR) ES cells. (C) PCR analysis of genomic DNA isolated from Zfp36l2 WT, heterozygous, and KO mice using PCR primers F1, F2, and R2. (D) Northern blot of total cellular RNA (15 μg) isolated from E14.5 WT and KO fetal liver and hybridized with a ³²P-labeled 787-bp 3′UTR probe for Zfp36l2.