Transmembrane collagen XVII is a novel component of the glomerular filtration barrier.

The kidney filtration barrier consists of the capillary endothelium, the glomerular basement membrane and the slit diaphragm localized between foot processes of neighbouring podocytes. We report that collagen XVII, a transmembrane molecule known to be required for epithelial adhesion, is expressed in podocytes of normal human and mouse kidneys and in endothelial cells of the glomerular filtration barrier. Immunoelectron microscopy has revealed that collagen XVII is localized in foot processes of podocytes and in the glomerular basement membrane. Its role in kidney has been analysed in knockout mice, which survive to birth but have high neonatal mortality and skin blistering and structural abnormalities in their glomeruli. Morphometric analysis has shown increases in glomerular volume fraction and surface densities of knockout kidneys, indicating an increased glomerular amount in the cortex. Collagen XVII deficiency causes effacement of podocyte foot processes; however, major slit diaphragm disruptions have not been detected. The glomerular basement membrane is split in areas in which glomerular and endothelial basement membranes meet. Differences in the expression of collagen IV, integrins α3 or ß1, laminin α5 and nephrin have not been observed in mutant mice compared with controls. We propose that collagen XVII has a function in the attachment of podocyte foot processes to the glomerular basement membrane. It probably contributes to podocyte maturation and might have a role in glomerular filtration.

Significant Role of Collagen XVII And Integrin ß4 in Migration and Invasion of The Less Aggressive Squamous Cell Carcinoma Cells.

Collagen XVII and integrin α6ß4 have well-established roles as epithelial adhesion molecules. Their binding partner laminin 332 as well as integrin α6ß4 are largely recognized to promote invasion and metastasis in various cancers, and collagen XVII is essential for the survival of colon and lung cancer stem cells. We have studied the expression of laminin γ2, collagen XVII and integrin ß4 in tissue microarray samples of squamous cell carcinoma (SCC) and its precursors, actinic keratosis and Bowen's disease. The expression of laminin γ2 was highest in SCC samples, whereas the expression of collagen XVII and integrin ß4 varied greatly in SCC and its precursors. Collagen XVII and integrin ß4 were also expressed in SCC cell lines. Virus-mediated RNAi knockdown of collagen XVII and integrin ß4 reduced the migration of less aggressive SCC-25 cells in horizontal scratch wound healing assay. Additionally, in a 3D organotypic myoma invasion assay the loss of collagen XVII or integrin ß4 suppressed equally the migration and invasion of SCC-25 cells whereas there was no effect on the most aggressive HSC-3 cells. Variable expression patterns and results in migration and invasion assays suggest that collagen XVII and integrin ß4 contribute to SCC tumorigenesis.

Glucocorticoid receptors GRα and GRß are expressed in inflammatory dermatoses.

BACKGROUND: Glucocorticoids (GC) are the most commonly used anti-inflammatory drugs in dermatology. The actions of GCs are mediated by the glucocorticoid receptor (GR). Alternative splicing of GR mRNA gives rise to different isoforms, GRα and GRß being the most important. GRß antagonizes the activity of GRα and its up-regulation has been associated with glucocorticoid insensitivity in several non-cutaneous inflammatory diseases. METHODS: Using immunohistochemical stainings, we analyzed the expression of GRα and GRß in lesional skin samples of patients with atopic dermatitis, lichen ruber planus, eczema nummulare and lichen simplex chronicus. We also conducted a study of 13 severe atopic patients to investigate the effect of prednisolone treatment on the expression of GR isoforms using quantitative PCR, western blot and immunohistochemical analysis. RESULTS: GRα and GRß were expressed in atopic dermatitis, lichen ruber planus, eczema nummulare and lichen simplex chronicus. Our novel finding was that GRß is abundant in keratinocytes and cutaneous neutrophils. Nuclear staining of both GRα and GRß was strongest in keratinocytes of patients with lichen ruber planus, whereas the least nuclear positivity was detected in keratinocytes of patients with atopic dermatitis. In severe atopic dermatitis GRα and GRß were expressed in both peripheral blood mononuclear cells and the skin. The expression of GRα and GRß varied during prednisolone therapy but the changes were not related to treatment response or GC insensitivity. CONCLUSION: GRα and GRß are expressed in inflammatory dermatoses. In severe atopic dermatitis the increased expression of GRß mRNA is not connected to insensitivity against prednisolone treatment.

Collagen XVII expression correlates with the invasion and metastasis of colorectal cancer.

Collagen XVII has a well-established role as an adhesion molecule and a cell surface receptor located in the type I hemidesmosome of stratified epithelia. Its ectodomain is constitutively shed from the cell surface and suggested to regulate the adhesion, migration, and signaling of cutaneous epithelial cells. Collagen XVII was not previously thought to be expressed by colon epithelial cells. Immunohistochemical analysis of tissue microarray samples of 141 cases of colorectal carcinoma showed that collagen XVII is expressed in normal human colonic mucosa and colorectal carcinoma. In colorectal carcinoma, increased collagen XVII expression was significantly associated with higher TNM stage. It also correlated with infiltrative growth pattern and tumor budding as well as lymph node and distant metastasis. Increased collagen XVII expression was associated with decreased disease-free and cancer-specific survival. Immunofluorescence staining of collagen XVII and its well-known binding partner laminin γ2 chain demonstrated a partial colocalization in normal and tumor tissue. In vitro, the overexpression of murine collagen XVII promoted the invasion of CaCo-2 colon carcinoma cells through Matrigel (BD Biosciences; Bedford, MA). To conclude, this study reports for the first time the expression of collagen XVII in colon epithelium and the association of increased collagen XVII immunoexpression with poor outcome in colorectal carcinoma.