Relationship between Prion Diseases and Cholesterol?
Prion diseases are responsible for many of our neurodegenerative diseases including Parkinson’s and Alzheimers. Some process, as yet unidentified, causes the normal prions to fold over into an alternatively formed isoform that we call a PrPSC. It is this substance that is found in the brains of people who have died with a neurodegenerative disease. It is known that many of the neurodegenerative diseases are modified by the administration of drugs that inhibit cholesterol synthesis, so scientists set out to examine the effects of cholesterol balance within the neuronal cells themselves.
What they found was that prion infection caused an increase in the free cholesterol inside the contents of the cell, a process that could not be replicated by the stimulation of cholesterol synthesis. The presence of PrPSc increased solubilisation of the free cholesterol in cell membranes and affected their function. Only free cholesterol was increased, not the esters of cholesterol metabolism.
It was noted that the amount of free cholesterol was not because of cholesterol synthesis, but appeared to be one of stimulation by the PrPSCs. Metabolic pathways were stimulated by the prion infection that altered the membrane of the cell. These observations suggest that the neuropathogenesis of prion diseases results from PrPSc altering cholesterol-sensitive processes. They also raise questions regarding the membrane disturbances relative to cholesterol. Once these questions are further explored, we may finally make headway in the cure of these debilitating diseases.
We also need to look at prevention, not just cure. Mad-cow disease and downer cow/deer syndrome are known to be prion diseases. One might ask why a dietitian is interested in a prion based disease. It is because prions are a threat to our food chain. No one really knows the extent of a prion infection until it is almost too late. Just recently I posted an article on how downer cows were being taken to slaughter. We must not allow the powers that be to become lazy in their regulation of our food supply. Prion diseases can be hereditary. They are not something you want in your body or your food chain. This article is just one example of the presence of prions gone wrong.
Source:
Bate C, Tayebi M and A Williams. 2008. Sequestration of free cholesterol in cell membranes by prions correlates with cytoplasmic phospholipase A2 activation. BMC Biology:6(8).
http://www.sciencemag.org/feature/data/prusiner/245.dtl, accessed 3/22/08
About the Author
Kathy Shattler received her Master of Science degree from Michigan State University in E. Lansing Michigan in Human Nutrition. Her twenty-two years of practice includes holding positions as a Lecturer, Chief Clinical Dietitian and Program Manager. Kathy is the Founder of Nutri-Care Consulting and is currently the Nutrition Director of www.CEU4U.COM, an online continuing education management company for Registered Dietitians and Dietetic Technicians.
