Lysosomal compromise and brain dysfunction: examining the role of neuroaxonal dystrophy.
Lysosomal diseases are a family of over 50 disorders caused by defects in proteins critical for normal function of the endosomal/lysosomal system and characterized by complex pathogenic cascades involving progressive dysfunction of many organ systems, most notably the brain. Evidence suggests that compromise in lysosomal function is highly varied and leads to changes in multiple substrate processing and endosomal signalling, in calcium homoeostasis and endoplasmic reticulum stress, and in autophagocytosis and proteasome function. Neurons are highly vulnerable and show abnormalities in perikarya, dendrites and axons, often in ways seemingly unrelated to the primary lysosomal defect. A notable example is NAD (neuroaxonal dystrophy), which is characterized by formation of focal enlargements (spheroids) containing diverse organelles and other components consistent with compromise of retrograde axonal transport. Although neurons may be universally susceptible to NAD, GABAergic neurons, particularly Purkinje cells, appear most vulnerable and ataxia and related features of cerebellar dysfunction are a common outcome. As NAD is found early in disease and thus may be a contributor to Purkinje cell dysfunction and death, understanding its link to lysosomal compromise could lead to therapies designed to prevent its occurrence and thereby ameliorate cerebellar dysfunction.
Department of Neuroscience, Rose F. Kennedy Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA. steve.walkley@einstein.yu.edu
Steven U
SU
Walkley
Jakub
J
Sikora
Matthew
M
Micsenyi
Cristin
C
Davidson
Kostantin
K
Dobrenis
D000818:Animals; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D011992:Endosomes / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008247:Lysosomes / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D019150:Neuroaxonal Dystrophies / Q000473:pathology / Q000503:physiopathology*; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D000077296:Niemann-Pick C1 Protein; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011689:Purkinje Cells / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction / Q000502:physiology
D047908:Intracellular Signaling Peptides and Proteins; D000077296:Niemann-Pick C1 Protein; C106831:Npc1 protein, mouse; D011506:Proteins