Molecular characterization of IL-32 in human endothelial cells.
IL-32 is a newly discovered protein found in human and certain primates, but absent in rodent. Various reports suggest its role as a proinflammatory mediator. Since vascular endothelium is critical in inflammation, we investigate IL-32 in endothelial cells. We found that the gene is expressed in human endothelial cells and Akt strongly induces its expression. Sequence analysis indicates IL-32 beta as the major isoform in endothelial cells. Surprisingly, we did not detect any secretion of IL-32 beta in human endothelial cells; instead we observed co-localization of IL-32 beta with endoplasmic reticulum, suggesting IL-32 beta is an intracellular protein in these cells. Promoter analysis identified a minimum required region for IL-32 transcription at -0.1 to +0.5 kb around the initially identified transcription start site. We also defined a transcriptional suppressor-binding site at -2.0 to -1.5 kb. Importantly, RNA ligase mediated rapid amplification of cDNA ends in endothelial cells determined the transcription start site at the 328 bp downstream from the original identified site. Finally, we found a positive correlation of IL-32 levels with human breast cancer and glioblastoma multiforme (GBM). These findings improve our understanding of IL-32 in vascular endothelium. IL-32 expression might be valuable as a biomarker for cancer.
Kobayashi
Hanako
H
Department of Radiation Oncology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, 712 PRB, 2220 Pierce Ave., Nashville, TN 37232, USA.
Lin
P Charles
PC
D000818:Animals; D001483:Base Sequence; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000276:immunology*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007378:Interleukins / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site
C496971:IL32 protein, human; D007378:Interleukins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D051057:Proto-Oncogene Proteins c-akt