Research in the Cellular Neurology Unit focuses on the molecular mechanisms underlying a number of neurodegenerative disorders, including Parkinson's disease, dystonia, and hereditary spastic paraplegia. These disorders, which together afflict millions of Americans, worsen insidiously over a number of years, and treatment options are limited for many of them. Our laboratory is investigating inherited forms of these disorders, using molecular and cell biology approaches to study how mutations in disease genes ultimately result in cellular dysfunction. Over the past year, our laboratory has been concentrating on """"""""disease-related"""""""" members of the dynamin-like family of GTPases -- particularly atlastin-1, OPA1, and Drp1. We have found that the Drp1 GTPase, which is critical for mitochondrial division, interacts with the deafness-dystonia protein DDP. In on-going collaborations with Drs. Richard Youle (NINDS) and Morgan Sheng (HHMI, MIT), we are probing the role of this interaction in mitochondrial division as well as the deafness-dystonia syndrome. Another major project involves the characterization and functional analysis of the hereditary spastic paraplegia type 3A (SPG3A) protein, atlastin-1. We have recently found that although this protein is enriched in the Golgi apparatus, it is also highly enriched in axonal growth cones in neurons. Thus, atlastin-1 may be involved in ER-Golgi membrane dynamics as well as development of axons. Ongoing studies of atlastin-1 are focusing on how subtle changes in structure of the atlastin-1 protein resulting from disease-causing point mutations alter atlastin-1 GTPase activity, Golgi structure and dynamics, atlastin-1 oligomerization, and axonal growth. We have identified several other human atlastin-like proteins (atlastin-2 and -3) and are currently analyzing their localizations and functions. Another dynamin-lke GTPase mutated in an inherited neurological disorder, optic atrophy type 1, is the OPA1 protein. We have recently found that this protein, which is localized to the mitochondria, is critical for maintaining the cristae structure of the mitochondrial inner membrane. Mitochondria are undergoing continual fission and fusion within the cell, and OPA1 is required for proper mitochondrial fusion. The balance between fission and fusion is upset during programmed cell death, and mitochondria undergo extensive fragmentation. Interestingly, we have recently found that the OPA1 protein is released from mitochondria along with cytochrome c during programmed cell death, and we propose that this release may contribute to the increased fragmentation of mitochondria seen during programmed cell death. Lastly, we have recently begun studying the hereditary spastic paraplegia (SPG20; Troyer's syndrome) gene spartin. We have generated antibodies for localization studies, and yeast 2-hybrid screening has identified several interacting proteins, including the endocytic protein Eps15. We anticipate that these studies will allow us to unravel the cellular functions of the SPG20 protein spartin, as well as the effects of patient mutations on these cellular functions. Taken together, we expect that our studies will advance our understanding of the molecular pathogenesis of the hereditary neurological disorders discussed above. Such an understanding at the molecular and cellular levels will hopefully lead to novel treatments to prevent progression of these disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Intramural Research (Z01)
Project #
1Z01NS002992-04
Application #
7143916
Study Section
(CNU)
Project Start
Project End
Budget Start
Budget End
Support Year
4
Fiscal Year
2005
Total Cost
Indirect Cost
City
State
Country
United States
Zip Code
Hu, Junjie; Shibata, Yoko; Zhu, Peng-Peng et al. (2009) A class of dynamin-like GTPases involved in the generation of the tubular ER network. Cell 138:549-61
Bakowska, Joanna C; Wang, Heng; Xin, Baozhong et al. (2008) Lack of spartin protein in Troyer syndrome: a loss-of-function disease mechanism? Arch Neurol 65:520-4
Rismanchi, Neggy; Soderblom, Cynthia; Stadler, Julia et al. (2008) Atlastin GTPases are required for Golgi apparatus and ER morphogenesis. Hum Mol Genet 17:1591-604
Papapetropoulos, Spiridon; Friedman, Jennifer; Blackstone, Craig et al. (2007) A progressive, fatal dystonia-Parkinsonism syndrome in a patient with primary immunodeficiency receiving chronic IVIG therapy. Mov Disord 22:1664-6
Meijer, Inge A; Dion, Patrick; Laurent, Sandra et al. (2007) Characterization of a novel SPG3A deletion in a French-Canadian family. Ann Neurol 61:599-603
Bakowska, Joanna C; Jupille, Henri; Fatheddin, Parvin et al. (2007) Troyer syndrome protein spartin is mono-ubiquitinated and functions in EGF receptor trafficking. Mol Biol Cell 18:1683-92
Zhu, Peng-Peng; Soderblom, Cynthia; Tao-Cheng, Jung-Hwa et al. (2006) SPG3A protein atlastin-1 is enriched in growth cones and promotes axon elongation during neuronal development. Hum Mol Genet 15:1343-53
Blindauer, Karen; Shoulson, Ira; Oakes, David et al. (2006) A randomized controlled trial of etilevodopa in patients with Parkinson disease who have motor fluctuations. Arch Neurol 63:210-6
Soderblom, Cynthia; Blackstone, Craig (2006) Traffic accidents: Molecular genetic insights into the pathogenesis of the hereditary spastic paraplegias. Pharmacol Ther 109:42-56
Arnoult, Damien; Grodet, Alain; Lee, Yang-Ja et al. (2005) Release of OPA1 during apoptosis participates in the rapid and complete release of cytochrome c and subsequent mitochondrial fragmentation. J Biol Chem 280:35742-50

Showing the most recent 10 out of 16 publications