title: Seminolipid and its precursor/degradative product, galactosylalkylacylglycerol, in the testis of saposin A- and prosaposin-deficient mice.
abstract: Sphingolipid activator proteins (saposins A, B, C, and D) are derived from a common precursor protein (prosaposin) and specifically activate in vivo degradation of glycolipids with short carbohydrate chains. A mouse model of prosaposin deficiency (prosaposin-/-) closely mimics the human disease with an elevation of multiple glycolipids. The recently developed saposin A-/- mice showed a chronic form of globoid cell leukodystrophy, establishing the essential in vivo role of saposin A as an activator for galactosylceramidase to degrade galactosylceramide. Seminolipid, the principal glycolipid in spermatozoa, and its precursor/degradative product, galactosylalkylacylglycerol (GalEAG), were analyzed in the testis of the two mouse mutants by electrospray ionization mass spectrometry. Saposin A-/- mice showed the normal seminolipid level, while that of prosaposin-/- mice was approximately 150% of the normal level at the terminal stage. In contrast, GalEAG increased up to 10 times in saposin A-/- mice, whereas it decreased with age in the wild-type as well as in prosaposin-/- mice. These analytical findings on the two saposin mutants may shed some light on the physiological function of seminolipid and GalEAG.
authors.affiliation: Department of Biochemistry, Teikyo University School of Medicine, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Tadano-Aritomi
authors.forename: Junko
authors.initials: J
authors.lastname: Matsuda
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Fujimoto
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Suzuki
authors.forename: Ineo
authors.initials: I
authors.lastname: Ishizuka
mesh_terms: D000818:Animals; D005697:Galactosides / Q000378:metabolism; D017353:Gene Deletion; D005989:Glycerides / Q000032:analysis / Q000378:metabolism*; D006017:Glycolipids / Q000032:analysis / Q000378:metabolism*; D006023:Glycoproteins / Q000172:deficiency* / Q000235:genetics; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D018345:Mice, Knockout; D015394:Molecular Structure; D010641:Phenotype; D049231:Saposins; D013109:Sphingomyelins / Q000378:metabolism; D013737:Testis / Q000378:metabolism* / Q000473:pathology
chemical_list: D005697:Galactosides; D005989:Glycerides; D006017:Glycolipids; D006023:Glycoproteins; C483345:PSAP protein, human; C483344:Psap protein, mouse; D049231:Saposins; D013109:Sphingomyelins; C009233:seminolipid