Intracellular Abnormalities in Human Infantile Neuronal Ceroid Lipofuscinosis Patient Cells

Infantile Neuronal Ceroid Lipofuscinosis (INCL) is a lysosomal storage disorder which causes neurodegeneration during early childhood. Between 6 and 24 months of age, INCL patients present with severe and progressively life threatening behavioral, cognitive, biochemical, and neuroanatomical abnormalities. While the clinical course of INCL is well characterized, an efficacious treatment regimen has yet to be established. INCL results from genetic abnormalities in the Palmitoyl Protein Thioesterase (ppt1) gene, which encodes for a crucial lysosomal enzyme. When children are born with two defective copies of the ppt1 gene, the insufficient activity of this enzyme causes improper lysosomal function. The specific pathology is unknown, however, patients with INCL develop characteristic autofluorescent storage deposits within the lysosomes of the cell, as a result of diminished PPT1 enzyme activity. Leading theories propose that the accumulation of this lysosomal storage material leads to heightened reactive oxygen species (ROS) in the central nervous system, which causes cell death. Previously, our laboratory has identified embryonic neurodevelopmental abnormalities in a Drosophila model of INCL. Subcellular abnormalities in the organelles of human cells derived from a patient with INCL were also observed. In the present work, we further describe organellar abnormalities that arise in a human primary cell line model of INCL, and how these abnormalities may indicate, or even lead to, specific intracellular signaling pathways contributing to cell death. Additionally, we are in the process of inducing pluripotency in this primary cell line to generate a PPT1 deficient induced pluripotent stem cell line (iPSC). These iPSCs will then be used to observe subcellular abnormalities in various differentiated CNS cell subtypes.