Anti-DKK4 monoclonal antibody, clone NN1583-0N20

PURPOSE. The aim of this study was to identify differentially expressed genes in the human limbal epithelium by microarray analysis. METHODS. Total RNA isolates of human limbal and central corneal epithelia were used after transcription for hybridization on whole human genome expression microarrays. A set of differentially expressed genes detected by both microarrays was established. In the case of eight selected molecules, microarray results were confirmed by qRT-PCR, and protein expression in the cornea was examined by confocal immunofluorescence microscopy. Colocalization with the putative stem cell marker C/EBP delta was also examined. RESULTS. The authors established a database of 126 limbal overexpressed genes. qRT-PCR confirmed microarray results in all examined cases (SPON1, IFITM1, ITM2A, PHLDA1, CXCR4, EZD7, DCT, DKK4). Limbal localization of the protein product of SPON1, IFITM1, ITM2A, CXCR4, and DKK4 was shown with confocal immunofluorescence microscopy. SPON1, IFITM1, and ITM2A signals mostly colocalized with C/EBP delta-positive putative resting limbal stein cells. CONCLUSIONS. By detecting several new differentially expressed genes in the human corneal limbus, this study further expands current knowledge on the molecular signature of limbal epithelial stem cells. Plasma membrane localization of IFITM1 and ITM2A suggests their potential usefulness as targets to select stem cell-enriched populations from the limbal epithelium. (Invest Ophthalmol Vis Set. 2011;52:1252-1260) DOI: 10.1167/iovs.10-5242

Wnt/beta-catenin signaling plays a crucial role in the regulation of colon tissue regeneration and the development of colon tumors. Under physiological conditions, beta-catenin activity is tightly controlled. However, the majority of sporadic forms of colorectal cancer are characterized by inactivation of the tumor suppressor gene APC due to loss of heterozygosity ( LOH), resulting in deregulation of the protein beta-catenin. Apart from known beta-catenin target genes like MYC, OPG, and DKK4, the gene TNFRSF19, a member of the TNF receptor superfamily, is regulated by beta-catenin in mesenchymal stem cells ( hMSC). We found that TNFRSF19 is frequently overexpressed in colorectal cancer cell lines and primary colorectal carcinomas. Further characterization revealed that both isoforms of TNFRSF19, TNFRSF19.1 and TNFRSF19.2, are regulated in a beta-catenin dependent manner. The transcript TNFRSF19.2 encodes a 417 amino acid long protein containing a TRAF-binding site that links the TNFRSF19.2 to NF-kappa B signaling, whereas the isoform TNFRSF19.1 lacks this TRAF-binding site. Nevertheless both isoform 1 and 2 induced the activity of an NF-kappa B reporter gene. NF-kappa B signaling is important for inflammatory processes and chronic inflammatory diseases like ulcerative colitis and Crohn's disease, which are associated with increased risk for developing colorectal cancer. The observation that TNFRSF19 is a beta-catenin target gene and TNFRSF19 receptor molecules activate NF-kappa B signaling shows that beta-catenin regulates NF-kappa B activity via TNFRSF19, suggesting that TNFRSF19 may contribute to the development of colorectal tumors with deregulated beta-catenin activity.