Proteomics insights into infantile neuronal ceroid lipofuscinosis (CLN1) point to the involvement of cilia pathology in the disease.
Mutations in the depalmitoylation enzyme, palmitoyl protein thioesterase (PPT1), result in the early onset neurodegenerative disease known as Infantile Neuronal Ceroid Lipofuscinosis. Here, we provide proteomic evidence suggesting that PPT1 deficiency could be considered as a ciliopathy. Analysis of membrane proteins from brain enriched for acylated proteins from neonate Ppt1 knock out and control mice revealed a list of 88 proteins with differential expression levels. Amongst them, we identified Rab3IP, which regulates ciliogenesis in concert with Rab8 and Rab11. Immunostaining analysis revealed that PPT1 is localized in the cilia. Indeed, an unbiased proteomics analysis on isolated cilia revealed 660 proteins, which differed in their abundance levels between wild type and Ppt1 knock out. We demonstrate here that Rab3IP, Rab8 and Rab11 are palmitoylated, and that palmitoylation of Rab11 is required for correct intracellular localization. Cells and brain preparations from Ppt1-/- mice exhibited fewer cells with cilia and abnormally longer cilia, with both acetylated tubulin and Rab3IP wrongly distributed along the length of cilia. Most importantly, the analysis revealed a difference in the distribution and levels of the modified proteins in cilia in the retina of mutant mice versus the wildtype, which may be important in the early neurodegenerative phenotype. Overall, our results suggest a novel link between palmitoylated proteins, cilial organization and the pathophysiology of Neuronal Ceroid Lipofuscinosis.
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Michal
M
Segal-Salto
Department of Immunotechnology, Lund University, Medicon Village, Lund, Sweden and BTK, Åbo Academy University, Turku, Finland.
Karin
K
Hansson
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Tamar
T
Sapir
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Anna
A
Kaplan
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Talia
T
Levy
Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Michaela
M
Schweizer
Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Michael
M
Frotscher
Department of Immunotechnology, Lund University, Medicon Village, Lund, Sweden and BTK, Åbo Academy University, Turku, Finland.
Peter
P
James
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Orly
O
Reiner
D000818:Animals; D001921:Brain / Q000378:metabolism; D002923:Cilia / Q000378:metabolism / Q000473:pathology; D057809:HEK293 Cells; D006801:Humans; D054878:Lipoylation; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D041681:NIH 3T3 Cells; D009472:Neuronal Ceroid-Lipofuscinoses / Q000235:genetics* / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D012160:Retina / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*
D008565:Membrane Proteins; D013869:Thiolester Hydrolases; C416054:PPT1 protein, human; C095299:palmitoyl-protein thioesterase