Genomic organization of the mouse <i>Lrig2</i> gene and the generation and molecular analyses of <i>Lrig2-</i>deficient mice.

<p>(<b>A</b>) Schematic drawing of the wild-type, conditional, and disrupted <i>Lrig2</i> alleles. A PKG-neo selection cassette was inserted downstream of exon 12. Exon 12 and the PKG-neo cassette were flanked by <i>loxP</i> sites and were deleted together, in a single step, by mating with OzCre mice. Color coding is as in <b>C</b>. (<b>B</b>) Southern blot using tail DNA isolated from the offspring of an Lrig2E12+/- × Lrig2E12+/- mating. The expected sizes are as follows: wild-type (<i>Lrig2E12</i>+) allele, 11.0 kb; and <i>Lrig2</i> exon 12-ablated (<i>Lrig2E12</i>-) allele, 6.6 kb. Lane B13 is from <i>Lrig2E12-/</i>-, lanes B10-12 and B14-15 are from <i>Lrig2E12+/-</i>, and the remaining lanes are from <i>Lrig2E12+/+</i> mice. (<b>C</b>) Genomic organization of the mouse <i>Lrig2</i> gene. Gene structure of <i>Mus musculus Lrig2</i> is shown. Gene organization was deduced from the sequence of the mouse genome and the <i>Lrig2</i> mRNA (GenBank accession number NM_001025067). Exons are indicated with boxes and are drawn to scale. Exon numbers are indicated with numbers. The <i>Lrig2</i> gene is approximately 58 kb, and it is located on mouse chromosome 3 F2. Color coding depicts the encoded protein domains, including a signal peptide (red), a leucine-rich repeats domain (yellow), three immunoglobulin-like domains (blue), a transmembrane domain (orange), and a cytosolic domain (green). (<b>D</b>) Western blot of MEF cell lines of different <i>Lrig2</i> genotypes. Top, anti-Lrig2 polyclonal; Bottom, anti-actin. (<b>E</b>) <i>Lrig</i> mRNA levels in mice of different genotypes. The mRNA levels of <i>Lrig1</i>, exon 12-containing <i>Lrig2</i> (<i>Lrig2E12</i>), exon 17-18 boundary-containing <i>Lrig2</i> (<i>Lrig2E17-18</i>), and <i>Lrig3</i> in brains of 3-week old mice were analyzed using quantitative real-time RT-PCR. The <i>Lrig/Rn18s</i> ratio was calculated and normalized to the corresponding ratio in reference RNA from Stratagene. Shown are the means of wild-type (n=6), <i>Lrig2E12+/-</i> (n=5), and <i>Lrig2E12-/</i>- (n=8) mice, with error bars indicating the standard deviations. Significant differences compared with the wild-type mice are indicated with asterisks (*p<0.01 and **p<0.001).