Fannie Chen, PhD
- ASSISTANT PROFESSOR | Genetics and Genomic Sciences
One Gustave L. Levy Place, Box 1498, New York, NY 10029
BA, Yale University
PhD, Mount Sinai School of Medicine
Research in the lab is focused on the biology of the endosomal/lysosomal (E/L) system, with particular focus on the defects underlying Niemann-Pick Type C (NPC) disease. NPC disease is a rare autosomal recessive lipidosis whose patients exhibit progressive neurodegeneration and hepatosplenomegaly, leading to death during early childhood. The majority of NPC patients carry mutations in NPC1, which encodes a large late endosomal transmembrane protein whose exact function remains unclear. Several studies have shown that NPC1 cells have a generalized transport block from late endosomes to the trans-Golgi network (TGN), suggesting that the NPC1 protein functions to facilitate vesicle movement and/or fusion with target membranes such as the TGN.
Work in our lab has shown that telomerase (TeRT)-immortalization of cells from NPC1 patients results in the correction of the cellular lipid storage phenotype. Furthermore, these effects on the E/L system are independent of NPC1 protein function, suggesting that TeRT-immortalization produces changes that are responsible for the alteration of specific lipid transport pathways from the E/L system to the TGN and plasma membrane. Characterization of these protein/gene expression changes as they relate to the function of the E/L system will yield new clues regarding the mechanisms and regulation of these pathways.
Another focus of our research is the development of new paradigms for the treatment of NPC and other lysosomal storage disorders (LSDs) with neuropathology. LSDs such as NPC result from a partial or total lack of a specific protein. There are only two ways to replace a missing or malfunctioning protein: 1) provide/introduce the protein exogenously as in enzyme/protein replacement therapy, or 2) introduce the gene encoding the necessary protein by gene therapy. Both of these approaches are not currently suitable for disorders with neuropathology due to the inaccessibility of the brain resulting from the blood-brain barrier. Our studies provide a new strategy for the identification of pharmacologically relevant molecules with the potential for treatment of NPC1 disease, which should also be applicable to many other lysosomal diseases with neuropathology that preclude the application of straightforward treatment options.
Walter M, Chen FW, Tamari F, Wang R, Ioannou YA. Endosomal Lipid Accumulation in NPC1 Leads to Inhibition of PKC, Hypophosphorylation of Vimentin, and Rab9 Entrapment. Biol Cell 2008; epub.
Chen FW, Gordon RE, Ioannou YA. NPC1 late Endosomes Contain Elevated Levels of Non-Esterified ('free') Fatty Acids and an Abnormally Glycosylated Form of the NPC2 Protein. Biochem J. 2005; 390: 549-561.
Davies JP, Ioannou YA, Chen FW. Transmembrane Molecular Pump Activity of Niemann-Pick C1 Protein. Science; 290: 2295-2298.
Higgins ME, Ioannou YA, Chen FW, Davies JP. Niemann-Pick C1 is a late Endosome-resident Protein that Transiently Associates with Lysosomes and the Trans-Golgi Network. Mol Gen Metab 1999; 68: 1-13.
Ioannou YA, Chen FW. Ribosomal Proteins in Cell Proliferation and Apoptosis. Intern Rev Immunol 1999; 18: 429-448.
Chen FW, Ioannou YA, Davies JP. Differential Gene Expression in Apoptosis: Identification of Ribosomal Protein 23K, a Cell proliferation Inhibitor. Mol Gen Metab 1998; 64: 271-282.
Chen FW, Ioannou YA. Quantitation of DNA Fragmentation in Apoptosis. Nucl Acids Res 1996; 24: 992-993.
Walter M, Chen FW. Biol Cell . Biol Cell 2009; 101(141-152).