Structure of the 5'region of the human NOD2 gene and expression of transcript isoforms. (A) Sequence of the novel two exons in the genomic context. Exons are capitalized, ATGs representing upstream ORFs are in bold print. The productive ATG used as an alternative translation start in exon 2 is marked by an asterisk. (B) Graphical representation of the alternatively spliced isoforms from the two alternate promoters. STP, stop codon of the uORFs. Below is a representation of the alternatively translated protein isoforms depicted by single letter amino acid code. (1) denotes the original start in the canonical exon 1, (2) denotes the alternative start in exon 2 used by the two novel transcript isoforms. (C) Primary monocytes were treated with TNF-α (10 ng/ml) for 12 h. NOD2 was amplified as outlined and analyzed on agarose gels (D) Amplification of NOD2 in a human multiple tissue panel. Note the preponderance of the short isoform exon1a/2 in the leukocytes. (E) Densitometric analysis of RT-PCR experiments from colonic biopsies of healthy controls and inflamed tissue from Crohn disease patients. Depicted is the ratio between the short (exon1a/2) and the long (exon 1a/1b/2) isoform of NOD2 (**p < 0.002; *p < 0.05, Student's T-test, colonic samples from n = 8 healthy controls and n = 11 inflamed Crohn disease patients;n = 5 ileal samples from healthy controls and n = 5 inflamed ileal samples from Crohn disease patients).