Figure 3.

TAMPs are differentially expressed across epithelial tissues. (A) Analysis of TAMP transcript expression by semiquantitative RT-PCR reveals differential expression of marvelD3 splice variants, tricellulin, and occludin message in epithelial-rich mouse organs. (B) MarvelD3 splice variants (arrowheads) were each detected in mouse jejunal epithelium samples as determined by SDS-PAGE immunoblot analysis. Preincubation of polyclonal antisera with peptides used as immunogens eliminated the marvelD3 bands. (C) Analysis of TAMP expression across an array of mouse organs showed that marvelD3, tricellulin, and occludin proteins are differentially expressed in epithelium-rich tissues. (D) Immunofluorescence shows differential localization of marvelD3, tricellulin, and occludin (green) in vivo. All TAMP family members are concentrated at the apical intercellular junction of jejunal epithelia, hepatocytes, and renal tubular epithelium. In contrast, glomerular epithelial cells are enriched in marvelD3 and tricellulin, but largely lack occludin immunofluorescence. Nuclei (blue), ZO-1 (red), and H&E images (BB, brush border; TJ, tight junction; L, lumen; BLM, basolateral membrane; N, nucleus; BC, Bowman's capsule; M, mesenchyme; GT, glomerular tuft; US, urinary space) are shown for orientation. Bars, 10 μm. (E) Transmission immunoelectron microscopy of mouse jejunum demonstrates specific localization of marvelD3 to the tight junction in sagittal and en face orientations (arrowheads). Immunofluorescence insets with marvelD3 (green) and actin (red) are shown for orientation. Gray boxes approximate electron microscopic fields. White bars, 10 μm; black bars, 100 nm. Data are representative of ≥2 experiments, all with similar results.