Lysosomal ceroid depletion by drugs: therapeutic implications for a hereditary neurodegenerative disease of childhood.
Neuronal ceroid lipofuscinoses (NCLs) are the most common hereditary neurodegenerative diseases of childhood. The infantile form, INCL, is caused by lysosomal palmitoyl-protein thioesterase (PPT) deficiency, which impairs the cleavage of thioester linkages in palmitoylated proteins, preventing their hydrolysis by lysosomal proteinases. Consequent accumulation of these lipid-modified proteins (constituents of ceroid) in lysosomes leads to INCL. Because thioester linkages are susceptible to nucleophilic attack, drugs with this property may have therapeutic potential for INCL. We report here that two such drugs, phosphocysteamine and N-acetylcysteine, disrupt thioester linkages in a model thioester compound, [14C]palmitoyl approximately CoA. Most importantly, in lymphoblasts derived from INCL patients, phosphocysteamine, a known lysosomotrophic drug, mediates the depletion of lysosomal ceroids, prevents their re-accumulation and inhibits apoptosis. Our results define a novel pharmacological approach to lysosomal ceroid depletion and raise the possibility that nucleophilic drugs such as phosphocysteamine hold therapeutic potential for INCL.
Section on Developmental Genetics, Heritable Disorders Branch, The National Institute of Child Health and Human Development, The National Institutes of Health, Bethesda, Maryland, USA.
Z
Z
Zhang
J D
JD
Butler
S W
SW
Levin
K E
KE
Wisniewski
S S
SS
Brooks
A B
AB
Mukherjee
D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D002566:Ceroid / Q000378:metabolism*; D002648:Child; D018389:Codon, Nonsense; D003539:Cystaphos / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D007223:Infant; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D020125:Mutation, Missense; D009472:Neuronal Ceroid-Lipofuscinoses / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D010170:Palmitoyl-CoA Hydrolase / Q000172:deficiency / Q000235:genetics; D049231:Saposins
D002566:Ceroid; D018389:Codon, Nonsense; D006023:Glycoproteins; D049231:Saposins; D010171:Palmitoyl Coenzyme A; D010170:Palmitoyl-CoA Hydrolase; D000111:Acetylcysteine; D003539:Cystaphos