A recent article in Genetic Engineering and Biology News describes a study conducted by Gladstone Institute researchers that brings new insights to the role of genes in connection with Parkinson’s disease.
The team leader, Dr. Ken Nakamura, a UCSF associate of neurology, commented that this study provides an unprecedented and deeper understanding of the mitochondria’s life cycle. It explains that if the recycling process if these key proteins are mutated, it will cause Parkinson’s disease.
About Parkin and PINK1
The genes Parkin and PINK1 are associated with mitochondria (cell structures) that generate most of the energy in brain cells. PINK1 and Parkin initiate a process called mitophagy that decomposes damaged mitochondria. This process occurs in most cells.
But due to their continuous recycling, fusing, or splitting, their process is difficult to follow. To address this problem, the scientists created a process that produced larger than normal mitochondria. This allowed a more detailed examination under the microscope.
Dr. Nakamura said observation of damaged Parkin mitochondria fusing to other components had never occurred prior to the development of their new process.
Note that recycling is vital to the maintenance of healthy mitochondria. Any disruptions may cause neurodegeneration. Yet the role of PINK1 and Parkin is not clear with respect to neurons that also die as a result of Parkinson’s disease.
Neurons Present a Challenge
The researchers acknowledge that they do not yet understand the same process with respect to neurons. They also acknowledge that neurons exhibit high energy needs. The mitochondria in neurons show more resistance to disruption by Parkin than other types of cells.
The team reportedly identified Parkin proteins as they encircle damaged mitochondria, then target them for degradation. This was proof to the team that mitophagy in neurons begins in the same way that it begins in other cells.
The Nakamura study group examined mitochondria in living neurons to determine the overall effect of PINK1 and Parkin. Then they examined mitophagy in later phases. According to Dr. Huihui Li, the paper’s co-first author, the team has discovered a mitochondrial recycling pathway. He used the analogy that discovering the recycling pathway is similar to saving valuable belongings just before demolishing a house.
Looking Forward
Dr. Nakamura said that their future studies will examine how certain pathways lead to disease and how to target them therapeutically.
Specifically, the recycling pathway that has now been brought forward by the scientists is dependent upon PINK1 and Parkin. That could mean that mitochondrial recycling may be needed to preclude Parkinson’s neurodegeneration.
Dopamine neurons die in Parkinson’s disease. Dr. Nakamura pointed out that dopamine neurons are susceptible to PINK1 and Parkin mutations. The study elucidates the way these two proteins are able to recycle and degrade mitochondria.
Dr. Nakamura recommended more research in order to confirm whether the quality control of mitochondria as described in the study activates signaling pathways, including immune pathways and whether they cause neurons to be vulnerable to Parkin and PINK1 mutations.
