title: Distribution of prosaposin in the rat nervous system.
abstract: Prosaposin is the precursor of four sphingolipid activator proteins (saposins A, B, C, and D) for lysosomal hydrolases and is abundant in the nervous system and muscle. In addition to its role as a precursor of saposins in lysosomes, intact prosaposin has neurotrophic effects in vivo or in vitro when supplied exogenously. We examined the distribution of prosaposin in the central and peripheral nervous systems and its intracellular distribution. Using a monospecific antisaposin D antibody that crossreacts with prosaposin but not with saposins A, B, or C, immunoblot experiments showed that both the central and peripheral nervous systems express unprocessed prosaposin and little saposin D. Using the antisaposin D antibodies, we demonstrated that prosaposin is abundant in almost all neurons of both the central and peripheral nervous systems, including autonomic nerves, as well as motor and sensory nerves. Immunoelectron microscopy using double staining with antisaposin D and anticathepsin D antibodies showed strong prosaposin immunoreactivity mainly in the lysosomal granules in the neurons in both the central and peripheral nervous systems. The expression of prosaposin mRNA, examined using in situ hybridization, was observed in these same neurons. Our results suggest that prosaposin is synthesized ubiquitously in neurons of both the central and peripheral nervous systems.
authors.affiliation: Department of Neuropsychiatry, Ehime University Graduate School of Medicine, Toon, Ehime, 791-0212, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Hosoda
authors.forename: Kyojy
authors.initials: K
authors.lastname: Miyawaki
authors.forename: Shouichiro
authors.initials: S
authors.lastname: Saito
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Xue
authors.initials: X
authors.lastname: Bing
authors.forename: Takehiro
authors.initials: T
authors.lastname: Terashita
authors.forename: Naoto
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Araki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Shimokawa
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Hamada
authors.forename: Akira
authors.initials: A
authors.lastname: Sano
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Tanabe
authors.forename: Seiji
authors.initials: S
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D002490:Central Nervous System / Q000378:metabolism* / Q000648:ultrastructure; D006867:Hydrolases / Q000378:metabolism; D015151:Immunoblotting; D017403:In Situ Hybridization; D008247:Lysosomes / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D016253:Microscopy, Immunoelectron; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D017933:Peripheral Nervous System / Q000378:metabolism* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D049231:Saposins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism
chemical_list: C483347:Psap protein, rat; D012333:RNA, Messenger; D049231:Saposins; D006867:Hydrolases