SUMMARY Members of the insulin family of peptides have conserved roles in the regulation of growth and metabolism in a wide variety of metazoans. Here we show that Drosophila insulin-like peptide 6 (DILP6), which is structurally similar to vertebrate insulin-like growth factor (IGF), is predominantly expressed in the fat body, a functional equivalent of the vertebrate liver and adipocytes. This expression occurs during the postfeeding stage under the direct regulation of ecdysteroid. We further reveal that dilp6 mutants show growth defects during the postfeeding stage, which results in reduced adult body size through a decrease in cell number. This phenotype is rescued by fat body-specific expression of dilp6. These data indicate that DILP6 is a functional, as well as a structural, counterpart of vertebrate IGFs. Our data provide in vivo evidence for a role of ILPs in determining adult body size through the regulation of postfeeding growth.

Alzheimer's amyloid precursor protein (APP) 1 is an integral membrane protein with a receptor-like structure (1). A principal component of parenchymal amyloid deposits in Alzheimer's disease (AD) is ␤-amyloid (A␤) (2-4), which is derived from APP by proteolytic cleavage (1, 5-11). A␤ is thought to be generated through an intracellular protein secretory pathway of APP (for a review, see Ref. 12). The short APP cytoplasmic domain consisting of 47 amino acid residues is thought to be responsible for determination of APP metabolism (13-15) and possible signal transduction from a putative extracellular ligand that has yet to be identified (for a review, see Ref. 16). Because APP is a candidate pathogenic factor of AD, elucidation of the physiological function of APP as well as the determination of the metabolic mechanism of A␤ production should increase our understanding of the pathogenesis of AD. Using a yeast two-hybrid system, we isolated cDNA of proteins that interact with the cytoplasmic domain of APP (APP COOH ) in order to elucidate the molecular mechanisms of APP metabolism and function of APP. Previous efforts to identify and isolate proteins associating with APP COOH , utilizing the yeast two-hybrid system, have resulted in the isolation of proteins carrying phosphotyrosine binding/phosphotyrosine interaction (PI) domains such as Fe65 (17), 19), and X11 (20). The X11 gene, which is located on chromosome 9, was originally isolated as a gene candidate for Friedreich ataxia (21) and its partial cDNA was identified as a clone encoding a protein that associates with APP COOH (22). The PI domain of X11 interacts with the YENPTY motif of APP COOH (20). In the present study, we isolated a complete cDNA encoding an X11-like protein (X11L) from a human adult brain cDNA library, utilizing the yeast two-hybrid system and APP COOH as a bait. A partial short cDNA encoding approximately 190 amino acids in the PI domain of X11L has already been isolated using a similar procedure (22). However, detailed characterization of X11L binding to APP and identification of the role X11L plays in the physiological function of APP have not been performed. We found that human X11L requires a sequence containing the NPXY motif of APP COOH for APP binding and that association of the PI domain with APP was suppressed by a deletion of a amino-terminal domain fused to the PI domain (PI ϩ C construct) but enhanced by a deletion of a carboxyl-terminal domain fused to the PI domain (N ϩ PI construct). Co-transfection of full-length human X11L into cells that express stably transfected human APP695 cDNA resulted in decreased secretion of A␤40 but not A␤42. However, co-transfection into cells of the cDNA lacking the carboxyl-terminal domain (N ϩ PI construct) or a cDNA encoding only the PI domain (PI construct), whose protein products preserve the ability to bind to APP COOH , did not present the ability to modulate A␤ production. The present results suggest that the amino-terminal region of the PI domain is needed to regulate binding affinity...

IL-33, derived from colonic SEMFs, may play an important role in the pathophysiology of UC.

SummaryInterleukin (IL)-32 is a recently described proinflammatory cytokine, characterized by induction of nuclear factor (NF)-kB activation. We studied IL-32a expression in the inflamed mucosa of inflammatory bowel disease (IBD). We also investigated mechanisms regulating IL-32a expression. Tissue samples were obtained endoscopically or surgically from patients with ulcerative colitis (UC) (n = 10), Crohn's disease (CD) (n = 10), ischaemic colitis (n = 4) and normal colorectal tissues (n = 10). IL-32a expression was evaluated by standard immunohistochemical procedure. IL-32 mRNA expression was analysed by Northern blot. IL-32a was expressed weakly by colonic epithelial cells from normal individuals and subjects with ischaemic colitis. In the inflamed mucosa of IBD patients, epithelial IL-32a expression was increased markedly. In UC and CD patients, IL-32a expression was enhanced in affected mucosa compared to non-affected mucosa. In intestinal epithelial cell lines, expression of IL-32a mRNA and protein was enhanced by IL-1b, interferon (IFN)-g and tumour necrosis factor (TNF)-a. A combination of TNF-a plus IFN-g exerted synergistic effects. IL-32a induction by IL-1b and/or TNF-a was mediated by NF-kB activation. Epithelial IL-32a expression was increased in IBD patients, and in CD patients in particular. IL-32a might be involved in the pathophysiology of IBD as a proinflammatory cytokine and a mediator of innate immune response.