People with Parkinson’s are twice as likely to develop heart disease and have a 50% greater chance of dying from it. But why? The perplexing relationship between the two diseases has long troubled scientists. Now, Gerald W. Dorn II, M.D., and his colleague, Yun Chen, Ph.D. from Washington University in St. Louis have reported their findings in the April 26th edition of the journal “Science”. The path to this discovery was not straight and simple. For the past six years, this mystery has eluded scientific explanation.
All cells have mitochondria. Mitochondria are the little “factories” that covert fuel to provide energy to the cells. Brain and heart cells have tremendous needs for fuel and the energy provided by mitochondria. Cells are also equipped with a mechanism to help rid themselves of mitochondria that have stopped functioning or have become sick. If the sick mitochondria are not destroyed and are allowed to accumulate, they no longer manufacture the energy needed by the cell and start using it up themselves thus causing damage or death to the cells. This type of cell damage is what can lead to Parkinson’s or to heart disease. Scientists have understood the process, but did not understand the mechanism of how sick mitochondria could signal to the cell that they were in distress.
The researchers were working with the brains of mice and fruit flies and identified a protein known as mitofusion 2 (Mfn2). The usual role of Mfn2 is to fuse mitochondria together so they can exchange mitochondria DNA, as a form of primitive sexual reproduction. Now they have discovered that mitofusion 2 can change function under certain circumstances, something that no one has ever suspected.
In normal function to maintain cell integrity, mitochondria work to import the gene molecule called PINK. When they collect this PINK molecule, they work to destroy it. However, if the accumulation of PINK becomes too high, the Mfn2 can then change roles and bind with another gene molecule from within the cell itself called Parkin that signals the cell to destroy the mitochondria. In normal conditions, this is how mitochondria and cells undertake house cleaning to maintain cell health and function. But….if you have a mutation in the gene PINK or a mutation in the gene Parkin, you will get Parkinson’s.