Novel mechanisms for distal transport in developing and mature neurons

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DESCRIPTION (provided by applicant): The neuronal ceroid lipofuscinoses (NCLs) are a family of devastating neurodegenerative diseases resulting from mutations in as many as 14 different genes. Researchers have long sought a molecular link between various NCLs. Recent studies suggest a common NCL pathway associated specifically with membrane associated protein forms of the disease (CLN3, CLN6, CLN5, CLN8) may be intracellular transport via disrupted interaction with the cytoskeletal network. In support of this concept, we have identified a novel complex containing the ER-associated CLN6, whose mutation results in a variant late infantile NCL (vLINCL), the collapsin response mediator protein 2 (CRMP2), and the kinesin motor protein, KLC4. Acting through a network of protein interactions, CRMP2 regulates axonal/dendritic specification and extension during neurodevelopment and contributes to maintenance/regeneration in the mature brain. We hypothesize that the CRMP2/CLN6/KLC4 (CCK) complex utilizes CLN6 as a "molecular tag" on ER-vesicles for segregation of cargo to distal sites in dendrites and axons. Disruption of this signaling complex could contribute to the pathogenesis of vLINCL through altered neuronal process outgrowth and maintenance. To test this hypothesis, we propose aims that will 1) determine how the CCK complex regulates ER-vesicle transport development and maintenance of neurons; 2) define how CCK complex transport is linked to early events in neuronal differentiation and identify what cargo is transported by CLN6-tagged vesicles; and 3) determine if stabilization of CRMP2-associated complexes, independent of CLN6 rescue, could ameliorate neurological deficits in a pre- clinical NCL mouse model. These studies will expands our understanding of CLN6's contribution to crucial cellular processes and start to unravel the biological significance of the CCK complex in developing and mature neurons, as well as its role and the role of intracellular trafficking in neurological disorders such as the NCLs.