CHROMOSOMAL MAPPING AND EXPRESSION OF THE HUMAN B120 GENE

We previously reported a novel human cDNA, designated B120, containing a CAG repeat length polymorphism and many repeat units, loosely ident ified as YXQQP which is found in several human RNA binding proteins. I n the present study, the B120 gene was mapped to human chromosome 1p35 -36.1 by fluorescence in situ hybridization (FISH). Several human diso rders, including that of Schnyder crystalline corneal dystrophy, have been mapped to this region by genetic linkage. Schnyder crystalline co rneal dystrophy is thought to be a primary abnormality of corneal lipi d metabolism, resulting in opacification secondary to lipid accumulati on. In order to examine the function of B120, we introduced B120 cDNA with an expression vector into various cell lines including Cos1, C3H/ 10T1/2 and NIH/3T3 cells. These transfected cells exhibited small cyto plasmic spherical bodies. The cytoplasmic bodies appeared to be fat dr oplets on electron microscopy and histochemical staining. These findin gs suggested that B120 gene expression is associated with lipid metabo lism, and that overexpression of B120 may result in lipid deposition i n various cells, including those of fibroblastic cell lines. Since the cornea is composed of fibroblastic cells, overfunction of B120 could be related to the pathogenesis of Schnyder crystalline corneal dystrop hy. (C) 1998 Elsevier Science B.V. All rights reserved.