Expression pattern of the Nijmegen breakage syndrome gene, Nbs1, during murine development

The Nijmegen breakage syndrome (NBS; MIM 251260), is an autosomal recessive disease characterized by microcephaly, growth retardation, immunodeficienc y and cancer predisposition, NBS cells show spontaneous chromosomal instabi lity and hypersensitivity to ionizing radiation in combination with radiore sistant DNA synthesis, At the cellular level, NBS has some features in comm on with ataxia teleangiectasia, In this study the murine Nbs1 gene was used for an expression study in mouse embryos at different developmental stages as well as in adult mice. A low level of expression is observed in all tis sues. Highly specific expression was observed in organs with physiologic DN A double strand breakage (DSB), such as testis, thymus and spleen. Enhanced expression is also found at sites of high proliferative activity, These ar e the subventricular layer of the telencephalon and the diencephalon, the l iver, lung, kidney and gut, as well as striated and smooth muscle cells in various organs. In the adult cerebellum the postmitotic Purkinje cells are marked specifically, These expression patterns suggest that in addition to the role of the Nbs1 gene product as part of a DNA DSB repair complex, the Nbs1 gene product may serve further functions during development.