Membrane trafficking and mitochondrial abnormalities precede subunit c deposition in a cerebellar cell model of juvenile neuronal ceroid lipofuscinosis.
BACKGROUND
JNCL is a recessively inherited, childhood-onset neurodegenerative disease most-commonly caused by a approximately 1 kb CLN3 mutation. The resulting loss of battenin activity leads to deposition of mitochondrial ATP synthase, subunit c and a specific loss of CNS neurons. We previously generated Cln3Deltaex7/8 knock-in mice, which replicate the common JNCL mutation, express mutant battenin and display JNCL-like pathology.


RESULTS
To elucidate the consequences of the common JNCL mutation in neuronal cells, we used P4 knock-in mouse cerebella to establish conditionally immortalized CbCln3 wild-type, heterozygous, and homozygous neuronal precursor cell lines, which can be differentiated into MAP-2 and NeuN-positive, neuron-like cells. Homozygous CbCln3Deltaex7/8 precursor cells express low levels of mutant battenin and, when aged at confluency, accumulate ATPase subunit c. Recessive phenotypes are also observed at sub-confluent growth; cathepsin D transport and processing are altered, although enzyme activity is not significantly affected, lysosomal size and distribution are altered, and endocytosis is reduced. In addition, mitochondria are abnormally elongated, cellular ATP levels are decreased, and survival following oxidative stress is reduced.


CONCLUSIONS
These findings reveal that battenin is required for intracellular membrane trafficking and mitochondrial function. Moreover, these deficiencies are likely to be early events in the JNCL disease process and may particularly impact neuronal survival.
Fossale
Elisa
E
Molecular Neurogenetics Unit of Department of Neurology and Center for Human Genetic Research, Massachusetts General Hospital, Charlestown, MA, USA. efossale@partners.org <efossale@partners.org>
Wolf
Pavlina
P
Espinola
Janice A
JA
Lubicz-Nawrocka
Tanya
T
Teed
Allison M
AM
Gao
Hanlin
H
Rigamonti
Dorotea
D
Cattaneo
Elena
E
MacDonald
Marcy E
ME
Cotman
Susan L
SL
D000818:Animals; D001692:Biological Transport; D002402:Cathepsin D / Q000378:metabolism; D002460:Cell Line; D002531:Cerebellum / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D004195:Disease Models, Animal; D004705:Endocytosis; D006720:Homozygote; D008247:Lysosomes / Q000648:ultrastructure; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D008928:Mitochondria / Q000648:ultrastructure*; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D009472:Neuronal Ceroid-Lipofuscinoses / Q000235:genetics* / Q000473:pathology; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism / Q000648:ultrastructure
C102229:CLN3 protein, mouse; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D002402:Cathepsin D; C103607:mitochondrial ATPase subunit c; D025261:Mitochondrial Proton-Translocating ATPases