Figure 1.
Targeted disruption of the IL-1 gene family by homologous recombination. Genomic loci, targeting vectors, and mutated loci of IL-1α, IL-1β, and IL-1ra genes are indicated. (A) Targeting strategy for the IL-1α gene. A DNA fragment including exon 5 was replaced with the lacZ-PGK-hph-pA cassette (LacZ-hph). MC1-DT was ligated at the 5′ end of the vector for negative selection. (B) Targeting strategy for the IL-1β gene. A DNA fragment including exon 3–5 was replaced with the lacZ-PGK-neo-pA cassette (LacZ-neo). (C) Targeting strategy for the IL-1ra gene. A DNA fragment containing all the coding regions for the IL-1ra secretion form was replaced with the PGK-neo-pA cassette (neo). DT was ligated at the 5′ end of the vector for negative selection. Arrowheads, Primers (P1–P5) used for PCR. Striped lines, Probes for Southern blot analysis are indicated as 5′ and 3′ probes. Arrows, Expected sizes of DNA fragments obtained by restriction enzyme digestions. Black boxes, Exons. White boxes, Introns. Restriction enzyme sites are also indicated in the maps. w.t., Wild-type.