Researchers from the Mount Sinai Hospital have uncovered a defect in the process that controls the expression of the gene which they believe may have a part to play in the development of Huntingdon’s disease.
Protein complexes play an important role in this process; some silence genes, while others activate them. The protein complex, known as PRC2 for short, has been seen to have a vital part in the formation of specific classes of nerve cells as the brain develops. Now this Mount Sinai study has shown that PRC2 also plays a crucial role in the adult brain and that it may be implicated in the development of neurodegenerative diseases, including Huntingdon’s.
The region of the brain that controls our voluntary movements, the striatum, is mainly made of up of so called medium spiny neurons which express a specific set of genes to determine their unique identity and function. Once this specification has been established, the neurons need to remain the same in order to ensure normal motor function. While scientists were already aware that PRC2 worked to repress or silence specific genes and, in particular, was vital for normal development of the brain, they didn’t understand the part it had to play in maintaining the medium spiny neurons.
In order to find out more, the team from Mount Sinai engineered a mouse model that was lacking in PRC2 in the neurons of the forebrain. By observing the changes to the genes lacking in PRC2, they were able to see when, where and how the genetic material is activated. They discovered that the neurons in these mice exhibited a reactivation of the genes that are normally dormant in these particular cells. Furthermore, the genes that should be turned on in order to maintain function of the medium spiny neurons were inhibited. From this, the team were able to conclude that PRC2 has roles to play in both the brain development process and maintaining the identity of the medium spiny neurons into adult life. In short, it determined whether the neuron should live or die.
Upon further examination, the researchers found that the altered genes in these mouse models were those that are known to control the self-destruction process within brain cells. This was confirmed as the striatum of the engineered mice showed clear signs of cell death, and also had smaller brains than normal mice. Furthermore, they developed a progressive neurodegenerative disorder which was very much like Huntington’s disease.
The results of the study were published on August 15th 2016 in the online journal Nature Neuroscience.