Expression and genomic characterization of protein phosphatase inhibitor-1: a novel marker for mesothelium in the mouse

Protein phosphatase inhibitor-1 (inhibitor-1 or I-1) is involved in signal transduction and is an endogenous inhibitor of protein phosphatase-1. The m ouse I-I protein sequence has been deduced from cDNA and is strongly homolo gous to the published rat sequence. A mouse genomic library was screened, a nd the I-I gene was characterized and localized by fluorescent in situ hybr idization (FISH) to chromosome 15F. Protein expression in a range of embryo nic and adult tissue was analysed using confocal microscopy. Inhibitor-1 is expressed by: the coelomic epithelium; the epithelial bounding layer of ce lls of the kidney, lung, liver, heart, intestine and gonad; and the surface ectoderm. The blast cells of the kidney do not express I-1. We conclude th at I-1 is a marker for mesothelium. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.