IL-1 Family Cytokines Use Distinct Molecular Mechanisms to Signal through Their Shared Co-receptor.

Within the interleukin 1 (IL-1) cytokine family, IL-1 receptor accessory protein (IL-1RAcP) is the co-receptor for eight receptor-cytokine pairs, including those involving cytokines IL-1ß and IL-33. Unlike IL-1ß, IL-33 does not have a signaling complex that includes both its cognate receptor, ST2, and the shared co-receptor IL-1RAcP, which we now present here. Although the IL-1ß and IL-33 complexes shared structural features and engaged identical molecular surfaces of IL-1RAcP, these cytokines had starkly different strategies for co-receptor engagement and signal activation. Our data suggest that IL-1ß binds to IL-1RI to properly present the cytokine to IL-1RAcP, whereas IL-33 binds to ST2 in order to conformationally constrain the cognate receptor in an IL-1RAcP-receptive state. These findings indicate that members of the IL-1 family of cytokines use distinct molecular mechanisms to signal through their shared co-receptor, and they provide the foundation from which to design new therapies to target IL-33 signaling.

Serial analysis of gene expression in the corneal endothelium of Fuchs' dystrophy.

PURPOSE: To compare the gene expression profiles of normal human corneal endothelium with Fuchs' corneal endothelium, by using serial analysis of gene expression (SAGE). METHODS: Three pairs of normal human corneas were obtained from eye banks. Thirteen bisected Fuchs' corneal buttons were processed at the time of corneal transplantation. The endothelia of normal and Fuchs'-affected corneas were stripped, and total RNA was isolated. Serial analysis of gene expression (SAGE) was performed to identify and quantify gene transcripts. Genes over- and underexpressed by Fuchs' endothelium were limited to P < 0.01 by the method of Audic and Claverie. RESULTS: A total of 19,136 tags were identified with 9,530 from normal and 9,606 from Fuchs' endothelium. The expression of 18 transcripts was upregulated, and 36 transcripts were downregulated in Fuchs' endothelium compared with normal tissue. Upregulated transcripts included serum amyloid A1 and A2, metallothionein, and apolipoprotein D. Of the downregulated transcripts, 26 matched known genes, 3 matched expressed sequence tags (ESTs), and 7 were unknown to current databases. One downregulated transcript involved a newly reported bicarbonate transporter. Decreased transcripts related to antioxidants and proteins conferring protection against toxic stress were noted in Fuchs' versus normal endothelium including nuclear ferritin, glutathione S-transferase-pi, and heat shock 70-kDa protein. Nine different SAGE tags matching mitochondrial sequences accounted for 25% of the ESTs that were decreased in Fuchs' endothelium. CONCLUSIONS: SAGE analysis comparing normal to Fuchs' endothelium demonstrates diminished expression of mitochondrial, pump function, and antiapoptotic cell defense genes.

Gene expression in donor corneal endothelium.

OBJECTIVE: To report gene expression profiles of normal human corneal endothelium with microarray analysis and serial analysis of gene expression (SAGE). METHODS: Corneal endothelium was removed from normal human corneas obtained from eye banks. Total RNA was isolated and SAGE analysis was performed. The same RNA source was used to construct a complementary DNA library that was hybridized to microarrays containing 12 558 transcripts. RESULTS: A total of 9530 SAGE tags were sequenced, representing 4724 unique tags. Microarray analysis identified 542 distinct transcripts. A database of human corneal endothelial gene expression was compiled. Of the SAGE tags, 1720 matched known genes, 478 corresponded to expressed sequence tags, and 2526 had no known match to public databases. The 5 most abundantly expressed SAGE tags were cytochrome c oxidase subunit II, adenosine triphosphate synthase F(0) subunit 6, carbonic anhydrase XII, 12S ribosomal RNA, and ferritin, heavy polypeptide 1. Thirty-four percent of the transcripts (n = 1616) were specific to the corneal endothelium, when compared with other publicly available SAGE libraries. The 5 most abundant unique tags were keratin 12, angiopoietinlike factor, annexin A8, and 2 tags with no match to the database. Many endothelial pump function enzymes were confirmed, including several plasma membrane Na( +)/K(+) adenosine triphosphatases and a recently reported bicarbonate transporter. CONCLUSIONS: Corneal endothelial gene expression profiles by the current analysis provide an understanding of endothelial metabolism, structure, and function; enable comparisons to diseased endothelium; and provide baseline data that may lead to the discovery of novel endothelial genes.