Key findings are the expression gradient in the healthy adult colon and the involvement of novel gene families, as well as established candidate genes in the pathogenesis of ulcerative colitis.

Achaete-scute like (ASCL)2 is a basic helix-loop-helix transcription factor essential for the maintenance of proliferating trophoblasts during placental development. Using oligonucleotide microarrays we identified ascl2 as a gene significantly upregulated in colorectal adenocarcinomas (n ¼ 36 cancers, n ¼ 16 normals; 15-fold, Po0.0001). This finding was confirmed by quantitative reverse transcriptase (RT)-PCR on large intestinal cancers (n ¼ 29 cancers, n ¼ 16 normals; 10-fold, Po0.0001).In situ hybridization for ascl2 demonstrated expression at the base of small and large intestinal crypts (n ¼ 304), but in no other normal tissues excepting placenta. By in situ hybridization, 52-71% of colorectal adenomas (n ¼ 187), 50-73% of large (n ¼ 327) and 33-64% of small intestinal adenocarcinomas (n ¼ 124) were positive for ascl2 expression. Upregulation of murine ascl2 was also observed using oligonucleotide microarrays, quantitative RT-PCR and in situ hybridization on apc min/ þ and apc 1638N/ þ smad4 À/ þ tumours. Tumour cell lines stably transfected with LEF1 DN or APC2, or transiently transfected with short-interfering RNA (siRNA) against b-catenin showed a significant downregulation of ascl2. Colocalization of ascl2 with nuclear b-catenin was observed in 73 small intestinal adenocarcinomas (P ¼ 0.0008) and apc min/ þ tumours. Preliminary in vitro data suggest ascl2 may promote progression through the G2/M cell cycle checkpoint. In summary, ascl2 is a putative regulator of proliferation that is overexpressed in intestinal neoplasia.

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BackgroundHeparan sulfate proteoglycans (HSPGs) use highly sulfated polysaccharide side-chains to interact with several key growth factors and morphogens, thereby regulating their accessibility and biological activity. Various sulfotransferases and sulfatases with differing specificities control the pattern of HSPG sulfation, which is functionally critical. Among these enzymes in the mouse are two secreted 6-O-endosulfatases, Sulf1 and Sulf2, which modify HSPGs in the extracellular matrix and on the cell surface. The roles of Sulf1 and Sulf2 during normal development are not well understood.Methods/ResultsTo investigate the importance of Sulf1 and Sulf2 for embryonic development, we generated mice genetically deficient in these genes and assessed the phenotypes of the resulting secreted sulfatase-deficient mice. Surprisingly, despite the established crucial role of HSPG interactions during development, neither Sulf1- nor Sulf2-deficient mice showed significant developmental flaws. In contrast, mice deficient in both Sulf1and Sulf2 exhibited highly penetrant neonatal lethality. Loss of viability was associated with multiple, although subtle, developmental defects, including skeletal and renal abnormalities.ConclusionsThese results show that Sulf1 and Sulf2 play overlapping yet critical roles in mouse development and are redundant and essential for neonatal survival.

NF-κB–inducing kinase (NIK) is a primary regulator of the noncanonical NF-κB signaling pathway, which plays a vital role downstream of BAFF, CD40L, lymphotoxin, and other inflammatory mediators. Germline deletion or inactivation of NIK in mice results in the defective development of B cells and secondary lymphoid organs, but the role of NIK in adult animals has not been studied. To address this, we generated mice containing a conditional allele of NIK. Deletion of NIK in adult mice results in decreases in B cell populations in lymph nodes and spleen, similar to what is observed upon blockade of BAFF. Consistent with this, B cells from mice in which NIK is acutely deleted fail to respond to BAFF stimulation in vitro and in vivo. In addition, mice with induced NIK deletion exhibit a significant decrease in germinal center B cells and serum IgA, which is indicative of roles for NIK in additional pathways beyond BAFF signaling. Our conditional NIK-knockout mice may be broadly useful for assessing the postdevelopmental and cell-specific roles of NIK and the noncanonical NF-κB pathway in mice.