BRIEF COMMUNICATION Further Evidence for Mitochondrial Dysfunction in Progressive Supranuclear Palsy David S. Albers,* ,1 Russell H. Swerdlow,† Giovanni Manfredi,* Carl Gajewski,* Lichuan Yang,* W. Davis Parker, Jr.,† and M. Flint Beal* *Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, New York; and †Center for the Study of Neurodegenerative Diseases and the Department of Neurology, University of Virginia Health System, Charlottesville, Virginia Received July 18, 2000; accepted October 31, 2000 Recent data from our laboratory have identified a role for mitochondrial dysfunction in the pathogene- sis of progressive supranuclear palsy (PSP). To extend this finding, we measured key parameters of mito- chondrial function in platelet-derived cytoplasmic hy- brid (cybrid) cell lines expressing mitochondrial genes from patients with PSP. We observed significant de- creases in aconitase activity, cellular ATP levels, and oxygen consumption in PSP cybrids as compared to control cybrids, further suggesting a contributory role of impaired mitochondrial energy metabolism in PSP, possibly due to genetic abnormalities of mitochondrial DNA. © 2001 Academic Press Key Words: neurodegeneration; cybrids; ATP; oxy- gen; aconitase. Progressive supranuclear palsy (PSP) is a rare neu- rological disorder with rapid progression characterized by the appearance of supranuclear gaze palsy in addi- tion to extrapyramidal symptoms, which usually start during the sixth decade of life (17). The etiology of this disorder is unknown; however, accumulating evidence suggests a contributory role for impaired mitochon- drial function (for review, see 3). Numerous PET stud- ies have demonstrated defects in energy metabolism in PSP and recent data from this laboratory have demon- strated a significant reduction in -ketoglutarate de- hydrogenase complex (KGDHC) activity in postmortem PSP brain (2). Defects in oxidative phosphorylation have also been reported in muscle mitochondria from PSP patients (6). Together these studies provide com- pelling evidence for mitochondrial dysfunction under- lying the pathogenesis of PSP. Several neurodegenerative disorders, including Par- kinson’s disease (PD), Alzheimer’s disease (AD), Hun- tington’s disease (HD), and amyotrophic lateral sclero- sis (ALS), are associated with defects in mitochondrial function (for review, see 3). More specifically, studies with mitochondrially transformed cells (cybrids) have demonstrated that the transfer of mitochondria from affected subjects into mitochondrially depleted neuro- blastoma cells recapitulates the defects supporting the hypothesis of a pathophysiologic role of mitochondria in these diseases (16, 18, 19). Cybrid cell lines contain- ing mitochondria DNA (mtDNA) from platelets of PSP patients have recently been made (20). Thus, we have used this PSP cybrid cell system to search for evidence of mitochondrial dysfunction due to mtDNA abnormal- ities. Cybrids were prepared as described previously (20). Briefly, platelets from blood samples of patients meet- ing NINDS-SPSP criteria for probable PSP were iso- lated and fused with human neuroblastoma cells de- pleted of mitochondrial DNA using polyethylene glycol. Controls were either spouses of the patients or spouses of patients with other movement disorders attending the same referral clinic. The mean  SD age for the PSP patients was 72.7  8.4 years, and for the controls, it was 67.9  7.5 years (not statistically significant). Males and females were represented equally in each group. The resultant individual cybrid lines were expanded as “mixed” clonal populations, since discrete, trans- formed cell colonies were not isolated prior to the ini- tial passage. After at least 6 weeks of continuous cul- ture in selective media lacking uridine, the resultant cybrid lines were harvested for biochemical assays. All assays were performed blinded. 1 To whom correspondence should be addressed at Department of Neurology and Neuroscience, Room A-503, Weill Medical College of Cornell University, 525 East 68th Street, New York, NY 10021. Fax: (212) 746-8276. E-mail: daa2010@mail.med.cornell.edu. Experimental Neurology 168, 196 –198 (2001) doi:10.1006/exnr.2000.7607, available online at http://www.idealibrary.com on 196 0014-4886/01 $35.00 Copyright © 2001 by Academic Press All rights of reproduction in any form reserved.