PMID- 16542649 OWN - NLM STAT- MEDLINE DCOM- 20060721 LR - 20171116 IS - 0014-4827 (Print) IS - 0014-4827 (Linking) VI - 312 IP - 9 DP - 2006 May 15 TI - Palmitoyl protein thioesterase 1 (PPT1) deficiency causes endocytic defects connected to abnormal saposin processing. PG - 1540-53 AB - Infantile neuronal ceroid lipofuscinosis (INCL) is a severe neurodegenerative disorder of the childhood caused by mutations in the gene encoding palmitoyl protein thioesterase 1 (PPT1). PPT1 localizes to late endosomes/lysosomes of non-neuronal cells and in neurons also to presynaptic areas. PPT1-deficiency causes massive death of cortical neurons and most tissues show an accumulation of saposins A and D. We have here studied endocytic pathways, saposin localization and processing in PPT1-deficient fibroblasts to elucidate the cellular defects resulting in accumulation of specific saposins. We show that PPT1-deficiency causes a defect in fluid-phase and receptor-mediated endocytosis, whereas marker uptake and recycling endocytosis remain intact. Furthermore, we show that saposins A and D are more abundant and relocalized in PPT-deficient fibroblasts and mouse primary neurons. Metabolic labeling and immunoprecipitation analyses revealed hypersecretion and abnormal processing of prosaposin, implying that the accumulation of saposins may result from endocytic defects. We show for the first time a connection between saposin storage and a defect in the endocytic pathway of INCL cells. These data provide new insights into the metabolism of PPT1-deficient cells and offer a basis for further studies on cellular processes causing neuronal death in INCL and other neurodegenerative diseases. FAU - Ahtiainen, Laura AU - Ahtiainen L AD - National Public Health Institute, Department of Molecular Medicine, Biomedicum Helsinki, P.O. Box 104, 00251 Helsinki, Finland. FAU - Luiro, Kaisu AU - Luiro K FAU - Kauppi, Maria AU - Kauppi M FAU - Tyynela, Jaana AU - Tyynela J FAU - Kopra, Outi AU - Kopra O FAU - Jalanko, Anu AU - Jalanko A LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20060320 PL - United States TA - Exp Cell Res JT - Experimental cell research JID - 0373226 RN - 0 (Dextrans) RN - 0 (Lipoproteins, LDL) RN - 0 (Macrolides) RN - 0 (Saponins) RN - 0 (Saposins) RN - 0 (Transferrin) RN - 0 (fluorescein isothiocyanate bovine serum albumin) RN - 0 (fluorescein isothiocyanate dextran) RN - 0 (holotransferrin) RN - 27432CM55Q (Serum Albumin, Bovine) RN - 5142-23-4 (3-methyladenine) RN - 88899-55-2 (bafilomycin A1) RN - EC 3.1.2.- (Thiolester Hydrolases) RN - EC 3.1.2.22 (palmitoyl-protein thioesterase) RN - I223NX31W9 (Fluorescein-5-isothiocyanate) RN - JAC85A2161 (Adenine) SB - IM MH - Adenine/analogs & derivatives/pharmacology MH - Animals MH - CHO Cells MH - Cell Line MH - Cricetinae MH - Cricetulus MH - Dextrans/metabolism MH - Endocytosis/drug effects/genetics/*physiology MH - Fibroblasts/drug effects/metabolism/pathology MH - Fluorescein-5-isothiocyanate/analogs & derivatives/metabolism MH - Humans MH - Infant MH - Lipoproteins, LDL/metabolism MH - Macrolides/pharmacology MH - Mice MH - Mice, Inbred C57BL MH - Mice, Knockout MH - Neuronal Ceroid-Lipofuscinoses/genetics/metabolism/pathology MH - Saponins/*metabolism MH - Saposins/metabolism MH - Serum Albumin, Bovine/metabolism MH - Thiolester Hydrolases/*deficiency/genetics MH - Transferrin/metabolism EDAT- 2006/03/18 09:00 MHDA- 2006/07/22 09:00 CRDT- 2006/03/18 09:00 PHST- 2005/10/27 00:00 [received] PHST- 2006/01/17 00:00 [revised] PHST- 2006/01/18 00:00 [accepted] PHST- 2006/03/18 09:00 [pubmed] PHST- 2006/07/22 09:00 [medline] PHST- 2006/03/18 09:00 [entrez] AID - S0014-4827(06)00021-8 [pii] AID - 10.1016/j.yexcr.2006.01.034 [doi] PST - ppublish SO - Exp Cell Res. 2006 May 15;312(9):1540-53. doi: 10.1016/j.yexcr.2006.01.034. Epub 2006 Mar 20.