title: Characterization of cholesterol homeostasis in sphingosine-1-phosphate lyase-deficient fibroblasts reveals a Niemann-Pick disease type C-like phenotype with enhanced lysosomal Ca2+storage.
abstract: Sphingosine-1-phosphate (S1P) lyase irreversibly cleaves S1P, thereby catalysing the ultimate step of sphingolipid degradation. We show here that embryonic fibroblasts from S1P lyase-deficient mice (Sgpl1-/--MEFs), in which S1P and sphingosine accumulate, have features of Niemann-Pick disease type C (NPC) cells. In the presence of serum, overall cholesterol content was elevated in Sgpl1-/--MEFs, due to upregulation of the LDL receptor and enhanced cholesterol uptake. Despite this, activation of sterol regulatory element-binding protein-2 was increased in Sgpl1-/--MEFs, indicating a local lack of cholesterol at the ER. Indeed, free cholesterol was retained in NPC1-containing vesicles, which is a hallmark of NPC. Furthermore, upregulation of amyloid precursor protein in Sgpl1-/--MEFs was mimicked by an NPC1 inhibitor in Sgpl1+/+-MEFs and reduced by overexpression of NPC1. Lysosomal pH was not altered by S1P lyase deficiency, similar to NPC. Interestingly, lysosomal Ca2+content and bafilomycin A1-induced [Ca2+]iincreases were enhanced in Sgpl1-/--MEFs, contrary to NPC. These results show that both a primary defect in cholesterol trafficking and S1P lyase deficiency cause overlapping phenotypic alterations, and challenge the present view on the role of sphingosine in lysosomal Ca2+homeostasis.
authors.affiliation: Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Vienken
authors.affiliation: Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Mabrouki
authors.affiliation: Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Grabau
authors.affiliation: Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Ralf Frederik
authors.initials: RF
authors.lastname: Claas
authors.affiliation: Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Rudowski
authors.affiliation: Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Schömel
authors.affiliation: Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Pfeilschifter
authors.affiliation: Institut für Klinische Chemie und Klinische Pharmakologie, Universitätsklinikum Bonn, Bonn, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Lütjohann
authors.affiliation: Membranbiologie und Lipidbiochemie, Einheit des Life and Medical Sciences (LIMES) Instituts, Universität Bonn, Bonn, Germany.
authors.forename: Gerhild
authors.initials: G
authors.lastname: van Echten-Deckert
authors.affiliation: Institut für Allgemeine Pharmakologie und Toxikologie, Klinikum der Goethe-Universität, Frankfurt am Main, Germany.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Meyer Zu Heringdorf
mesh_terms: D000446:Aldehyde-Lyases / Q000097:blood / Q000172:deficiency*; D000818:Animals; D015415:Biomarkers; D002118:Calcium / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism*; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000378:metabolism*; D006655:Histone Deacetylases; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D052556:Niemann-Pick Disease, Type C / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype
chemical_list: D015415:Biomarkers; D002784:Cholesterol; D006655:Histone Deacetylases; D000446:Aldehyde-Lyases; C022649:sphingosine 1-phosphate lyase (aldolase); D002118:Calcium