Isolation of a set of genes expressed in the choroid plexus of the mouse using suppression subtractive hybridization

The choroid plexus produces cerebrospinal fluid, providing a specialized environment for the CNS. We previously demonstrated that choroid plexus ependymal cells can enhance nerve regeneration in vivo and promote neurite outgrowth in vitro. To understand the molecular mechanisms of choroid plexus functions, we isolated genes predominantly expressed in the mouse choroid plexus using suppression subtractive hybridization. Out of the 49 complementary DNA (cDNA) fragments isolated in two types of screening, 43 matched known sequences in the database and six were novel. In one type of screening where choroid plexus cDNAs were subtracted with cerebral cortex cDNAs, transthyretin and phosphodiesterase I alpha were predominant. This is consistent with previous reports and supports the authenticity of our approach. In the other type of screening, cDNAs derived from the choroid plexus of neonatal (postnatal day 5) mice were subtracted with cDNAs from the choroid plexus of adult mice. RNA blot and/or in situ hybridization confirmed abundant expression, in the mouse choroid plexus, of the mRNA encoding gelsolin, phospholipid transfer protein, ATP-binding cassette transporter A8 (ABCA8), androgen-inducible aldehyde reductase, and Na(+)/sulfate cotransporter SUT-1. Also, one novel gene (FS88) was found to be expressed in the choroid plexus from neonatal mice. Our data suggest that the choroid plexus cells produce molecules involved in processes such as prevention of fibrillization of amyloid beta-protein (transthyretin and gelsolin), lipid metabolism (phospholipid transfer protein and ABCA8), and detoxification (androgen-inducible aldehyde reductase).