Penn Medicine: Potential new drug target may protect against certain neurodegenerative diseases

(Press-News.org) PHILADELPHIA- Penn Medicine researchers have discovered that hypermethylation - the epigenetic ability to turn down or turn off a bad gene implicated in 10 to 30 percent of patients with Amyotrophic Lateral Sclerosis (ALS) and Frontotemporal Degeneration (FTD) - serves as a protective barrier inhibiting the development of these diseases. Their work, published this month in Neurology, may suggest a neuroprotective target for drug discovery efforts.

"This is the first epigenetic modification of a gene that seems to be protective against neuronal disease," says lead author Corey McMillan, PhD, research assistant professor of Neurology in the Frontotemporal Degeneration Center in the Perelman School of Medicine at the University of Pennsylvania. Expansions in the offending gene, C9orf72, have been linked with TAR DNA binding protein (TDP-43) which is the pathological source that causes ALS and FTD. "Understanding the role of C9orf72 has the possibility to be truly translational and improve the lives of patients suffering from these devastating diseases," says senior author, Edward Lee, MD, PhD, assistant professor of Neuropathology in Pathology and Laboratory Medicine at Penn.

McMillan and team evaluated 20 patients recruited from both the FTD Center and the ALS Center at the University of Pennsylvania who screened positive for a mutation in the C9orf72 gene and were clinically diagnosed with FTD or ALS. All patients completed a neuroimaging study, a blood test to evaluate C9orf72 methylation levels, and a brief neuropsychological screening assessment. The study also included 25 heathy controls with no history of neurological or psychiatric disease.

MRI revealed reduced grey matter in several regions that were affected in patients compared to controls. Grey matter is needed for the proper function of the brain in regions involved with muscle control, memory, emotions, speech and decision-making. Critically, patients with hypermethylation of C9orf72 showed more dense grey matter in the hippocampus, frontal cortex, and thalamus, regions of the brain important for the above described tasks and affected in ALS and FTD, suggesting that hypermethylation is neuroprotective in these regions.

To validate these findings, the Penn team also looked at autopsies of 35 patients with C9orf72 expansions and found that their pathology also suggested that increased methylation was associated with reduced neuronal loss in both the frontal cortex and hippocampus.

Longitudinal analysis was performed in 11 of the study patients to evaluate the neuroprotective effects of hypermethylation in individuals over their disease course. This showed reduced changes in grey matter of the hippocampus, thalamus, and frontal cortex, associated with hypermethlation suggesting that disease progresses more slowly over time in individuals with C9orf72 hypermethylation. Longitudinal neuropsychological assessments also showed a correlation between protected memory decline and hypermethylation.

These findings are consistent with a growing number of studies which have suggested the neuroprotective effects of the hypermethylation of C9orf72. "We believe that this work provides additional data supporting the notion that C9orf72 methylation is neuroprotective and therefore opens up the exciting possibility of a new avenue for precision medicine treatments and targets for drug development in neurodegenerative disease," says McMillan.

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Additional Penn authors include Jenny Russ, PhD; Elisabeth M. Wood, MSc; David J. Irwin, MD; Murray Grossman, MD, EdD; Leo McCluskey, MD; Lauren Elman, MD; and Vivianna Van Deerlin, MD, PhD.

This research was funded by the National Institutes of Health (AG043503, AG017586, AG039510, AG10124, AG032953) and the Wyncote Foundation. Dr. Lee is supported by the Doris Duke Charitable Foundation Clinical Scientist Development Award.

Penn Medicine is one of the world's leading academic medical centers, dedicated to the related missions of medical education, biomedical research, and excellence in patient care. Penn Medicine consists of the Raymond and Ruth Perelman School of Medicine at the University of Pennsylvania (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System, which together form a $4.9 billion enterprise. The Perelman School of Medicine has been ranked among the top five medical schools in the United States for the past 17 years, according to U.S. News & World Report's survey of research-oriented medical schools. The School is consistently among the nation's top recipients of funding from the National Institutes of Health, with $409 million awarded in the 2014 fiscal year. The University of Pennsylvania Health System's patient care facilities include: The Hospital of the University of Pennsylvania -- recognized as one of the nation's top "Honor Roll" hospitals by U.S. News & World Report; Penn Presbyterian Medical Center; Chester County Hospital; Penn Wissahickon Hospice; and Pennsylvania Hospital -- the nation's first hospital, founded in 1751. Additional affiliated inpatient care facilities and services throughout the Philadelphia region include Chestnut Hill Hospital and Good Shepherd Penn Partners, a partnership between Good Shepherd Rehabilitation Network and Penn Medicine. Penn Medicine is committed to improving lives and health through a variety of community-based programs and activities. In fiscal year 2014, Penn Medicine provided $771 million to benefit our community.