Brain region specific molecular changes in SCA1

Significance

There have been a number of studies in diverse subsets in neurodegenerative disorders using large scale transcriptomics and proteomics to access brain region-dependent molecular alterations. Through these studies gene clusters related to transcription, chromatin factors and mitochondria that appear to be specific to sub-brain regions including the cortex and striatum were identified.

Spinocerebellar ataxia type 1 (SCA1) is a fatal late-onset neurodegenerative disorder that is characterized by impaired motor coordination and balance, and also atrophy and loss of Purkinje cells in the cerebellum and cell death in the inferior olive identified in post mortem human tissue. A majority of previous studies in SCA1 has focused on neurodegenerative defects and their impacts on the cerebellum, but other brain affected regions such as the inferior olive have remained largely unstudied.

Thus, scientists at the Yale School of Medicine: Dr. Terri Driessen, Paul Lee and led by Professor Janghoo Lim set up a study to investigate the molecular and pathological signatures of the inferior olive with thorough comparison in two different SCA1 mouse models, and further identify similarities and differences in the gene expression profile between the inferior olive and the cerebellum. The research work is published in the journal eLife.

The research team discovered that at the early stage of SCA1 disease (i.e. 12 weeks old), in the Atxn1 knock-in (Atxn1154Q/2Q) inferior olive, a total of 204 genes were differentially regulated, with 43 annotated transcripts up-regulated and 161 down-regulated. Functional annotation clustering identified the defense response, which is the molecular response to a foreign body or injury, as the most highly enriched pathway, with other pathways associated with the defensive response being the immune response and the defense response to the virus. These findings may lead to new drug targets in the future.

The findings of Professor Janghoo Lim and his research team show for the first time that there are specific biological pathways enriched in the less studied SCA1 affected tissue, the inferior olive, and that there are intrinsic molecular differences between two affected tissues in SCA1 (the inferior olive and the cerebellum). This will inspire new ideas for targeting the disease in the two brain regions for better effective treatment.

These findings also show that there are different mechanisms of degeneration at work in the two brain tissues and suggest that further studies could be conducted to identify possible mechanism of degeneration in other parts of the brain.

Brain region specific molecular changes in SCA1 - Medicine Innovates

About the author

Janghoo Lim, Ph.D.

Associate professor of Genetics and Neuroscience
Yale School of Medicine

Dr. Lim is a native of Korea, where he received undergraduate and master’s degrees. He next moved to Houston, Texas, where he received a Ph.D. and postdoctoral trainings at Baylor College of Medicine. He joined Yale University in 2010 and is currently an Associate Professor in the Departments of Genetics and of Neuroscience, and in the Program of Cellular Neuroscience, Neurodegeneration and Repair. At Yale, he has explored the pathogenic mechanisms underlying diverse neurodegenerative diseases with an ultimate goal to translate his findings into the development of therapeutics to treat neurodegeneration.

Dr. Lim is a recipient of several awards including the NIH Pathway to Independence Award (2009), Yale Scholar Award (2010), NARSAD Young Investigator Award (2010), Young Investigator Award for SCA research from the National Ataxia Foundation (2012, 2014), Alfred P. Sloan Research Fellowship Award (2012), and Child Health Research Award from the Charles H. Hood Foundation (2012).

Reference

Driessen, T.M., Lee, P.J., Lim, J. Molecular pathway analysis towards understanding tissue vulnerability in spinocerebellar ataxia type 1. eLife 2018;7:e39981 doi: 10.7554/eLife.39981

Go To eLife 2018

About Priti