title: Chronological changes in prosaposin in the developing rat brain.
abstract: Prosaposin is the precursor protein of four glycoproteins, saposins A, B, C, and D, which activate sphingolipid hydrolases in lysosomes. Besides this role, intact prosaposin is also known as a potent neurotrophic factor that prevents neuronal cell death and stimulates neurite outgrowth in in vivo and in vitro experiments. In the present study, we examined chronological changes in prosaposin immunoreactivity in the rat brain using immunofluorescence staining and Diaminobenzidine (DAB) immunohistochemistry. In the hippocampal regions CA1, CA3, and dentate gyrus, the strongest staining of prosaposin was observed on postnatal day 1. The prosaposin immunoreactivity then decreased gradually until postnatal day 28. But in the cerebral cortex, prosaposin staining intensity increased from postnatal day 1 to 14, then decreased until postnatal day 28. The prosaposin immunoreactivity co-localized with the lysosomal granules labeled by an anti-Cathepsin D antibody, indicating that prosaposin mainly localized in the lysosomes of the neurons. We also examined the chronological changes in prosaposin mRNA and its two alternatively spliced variants using in situ hybridization. We found that both the mRNA forms, especially the one without a nine-base insertion, increased significantly from embryonic day 15 to postnatal day 7, then decreased gradually until postnatal day 28. Abundant prosaposin expression in the perinatal stages indicates a potential role of prosaposin in the early development of the rat brain.
authors.affiliation: Division of Anatomy and Embryology, Department of Integrated Basic Medical Science, Ehime University School of Medicine, Shitsukawa, To-on, Ehime 791-0295, Japan.
authors.forename: Bing
authors.initials: B
authors.lastname: Xue
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Huiling
authors.initials: H
authors.lastname: Gao
authors.forename: Shouichiro
authors.initials: S
authors.lastname: Saito
authors.forename: Naoto
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Shimokawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nabeka
authors.forename: Akira
authors.initials: A
authors.lastname: Sano
authors.forename: Seiji
authors.initials: S
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D018891:Dentate Gyrus / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D049231:Saposins / Q000378:metabolism* / Q000502:physiology; D013997:Time Factors
chemical_list: D011498:Protein Precursors; C483347:Psap protein, rat; D049231:Saposins