CLN3p impacts galactosylceramide transport, raft morphology, and lipid content.
Juvenile neuronal ceroid lipofuscinosis (JNCL) belongs to the neuronal ceroid lipofuscinoses characterized by blindness/seizures/motor/cognitive decline and early death. JNCL is caused by CLN3 gene mutations that negatively modulate cell growth/apoptosis. CLN3 protein (CLN3p) localizes to Golgi/Rab4-/Rab11-positive endosomes and lipid rafts, and harbors a galactosylceramide (GalCer) lipid raft-binding domain. Goals are proving CLN3p participates in GalCer transport from Golgi to rafts, and GalCer deficits negatively affect cell growth/apoptosis. GalCer/mutant CLN3p are retained in Golgi, with CLN3p rescuing GalCer deficits in rafts. Diminishing GalCer in normal cells by GalCer synthase siRNA negatively affects cell growth/apoptosis. GalCer restores JNCL cell growth. WT CLN3p binds GalCer, but not mutant CLN3p. Sphingolipid content of rafts/Golgi is perturbed with diminished GalCer in rafts and accumulation in Golgi. CLN3-deficient raft vesicular structures are small by transmission electron microscopy, reflecting altered sphingolipid composition of rafts. CLN1/CLN2/CLN6 proteins bind to lysophosphatidic acid/sulfatide, CLN6/CLN8 proteins to GalCer, and CLN8 protein to ceramide. Sphingolipid composition/morphology of CLN1-/CLN2-/CLN6-/CLN8- and CLN9-deficient rafts are altered suggesting changes in raft structure/lipid stoichiometry could be common themes underlying these diseases.
Rusyn
Elena
E
Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Mousallem
Talal
T
Persaud-Sawin
Dixie-Ann
DA
Miller
Sara
S
Boustany
Rose-Mary N
RM
D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D049109:Cell Proliferation; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005699:Galactosylceramides / Q000172:deficiency / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism*; D021962:Membrane Microdomains / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009472:Neuronal Ceroid-Lipofuscinoses / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding; D021381:Protein Transport; D013347:Subcellular Fractions; D013433:Sulfoglycosphingolipids / Q000378:metabolism; D000091346:Tripeptidyl-Peptidase 1
C105199:CLN3 protein, human; C102229:CLN3 protein, mouse; C498493:Cln8 protein, mouse; D005699:Galactosylceramides; D008562:Membrane Glycoproteins; D008563:Membrane Lipids; D008565:Membrane Proteins; D018832:Molecular Chaperones; D013433:Sulfoglycosphingolipids; C000717268:Tpp1 protein, mouse; D000091346:Tripeptidyl-Peptidase 1; C000717267:TPP1 protein, human