title: Differential expression of the alternatively spliced forms of prosaposin mRNAs in rat choroid plexus.
abstract: Prosaposin has two distinct profiles. One is a precursor form that is processed into saposins thus promoting lysosomal sphingolipid hydrolase function, whereas the other is an intact form that is not processed into saposins but is abundant in certain tissues and secretory fluids, including the cerebrospinal fluid. In rats, alternative splicing in the prosaposin gene generates mRNAs with and without a 9-base insertion (Pro+9 and Pro+0 mRNAs, respectively). Pro+9 mRNA is reported to be preferentially expressed in tissues in which the intact form of prosaposin dominates, whereas Pro+0 mRNA is preferentially expressed in tissues in which the precursor dominates. The expression patterns of Pro+9 and Pro+0 mRNAs in the rat choroid plexus are examined in the present study. The specificities of 36-mer oligonucleotide probes used to detect the 9-base insertion by in situ hybridization were demonstrated by dot-blot hybridization. Next, these probes were used for in situ hybridization, which showed predominant expression of Pro+0 mRNA and weak expression of Pro+9 mRNA in the choroid plexus. These expression patterns were confirmed by reverse transcription plus the polymerase chain reaction with AlwI restriction enzyme treatment. Expression of the intact form of prosaposin in the choroid plexus was assessed by Western blotting and immunohistochemistry. Because the choroid plexus is responsible for the generation of cerebrospinal fluid containing the intact form of prosaposin, the present study raises the possibility that Pro+0 mRNA is related to the intact form in the choroid plexus and that the alternatively spliced forms of mRNAs do not simply correspond to the precursor and intact forms of prosaposin.
authors.affiliation: Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, Yanagido, Gifu, 501-1128, Japan, shouichi@gifu-u.ac.jp.
authors.forename: Shouichiro
authors.initials: S
authors.lastname: Saito
authors.forename: Kyoko
authors.initials: K
authors.lastname: Saito
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nabeka
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Shimokawa
authors.forename: Naoto
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Matsuda
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D020029:Base Pairing / Q000235:genetics; D001483:Base Sequence; D015153:Blotting, Western; D002831:Choroid Plexus / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D015347:RNA Probes / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015183:Restriction Mapping; D020133:Reverse Transcriptase Polymerase Chain Reaction; D049231:Saposins / Q000235:genetics* / Q000378:metabolism
chemical_list: D020033:Protein Isoforms; C483347:Psap protein, rat; D015347:RNA Probes; D012333:RNA, Messenger; D049231:Saposins