Novel interactions of CLN5 support molecular networking between Neuronal Ceroid Lipofuscinosis proteins.
BACKGROUND
Neuronal ceroid lipofuscinoses (NCLs) comprise at least eight genetically characterized neurodegenerative disorders of childhood. Despite of genetic heterogeneity, the high similarity of clinical symptoms and pathology of different NCL disorders suggest cooperation between different NCL proteins and common mechanisms of pathogenesis. Here, we have studied molecular interactions between NCL proteins, concentrating specifically on the interactions of CLN5, the protein underlying the Finnish variant late infantile form of NCL (vLINCLFin).


RESULTS
We found that CLN5 interacts with several other NCL proteins namely, CLN1/PPT1, CLN2/TPP1, CLN3, CLN6 and CLN8. Furthermore, analysis of the intracellular targeting of CLN5 together with the interacting NCL proteins revealed that over-expression of PPT1 can facilitate the lysosomal transport of mutated CLN5FinMajor, normally residing in the ER and in the Golgi complex. The significance of the novel interaction between CLN5 and PPT1 was further supported by the finding that CLN5 was also able to bind the F1-ATPase, earlier shown to interact with PPT1.


CONCLUSIONS
We have described novel interactions between CLN5 and several NCL proteins, suggesting a modifying role for these proteins in the pathogenesis of individual NCL disorders. Among these novel interactions, binding of CLN5 to CLN1/PPT1 is suggested to be the most significant one, since over-expression of PPT1 was shown to influence on the intracellular trafficking of mutated CLN5, and they were shown to share a binding partner outside the NCL protein spectrum.
Lyly
Annina
A
National Institute for Health and Welfare (THL), Biomedicum Helsinki, Finland and FIMM, Institute for Molecular Medicine in Finland. annina.lyly@helsinki.fi
von Schantz
Carina
C
Heine
Claudia
C
Schmiedt
Mia-Lisa
ML
Sipilä
Tessa
T
Jalanko
Anu
A
Kyttälä
Aija
A
D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009472:Neuronal Ceroid-Lipofuscinoses / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D006180:Proton-Translocating ATPases / Q000378:metabolism; D000091346:Tripeptidyl-Peptidase 1
C113332:CLN5 protein, human; C488572:Cln5 protein, mouse; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C000717268:Tpp1 protein, mouse; D000091346:Tripeptidyl-Peptidase 1; C000717267:TPP1 protein, human; D006180:Proton-Translocating ATPases