For Part 2: http://dialoguewithdisability.blogspot.co.uk/2013/04/gretchen-amphlet-parkinsons-uk-lecture_24.html
Understanding why nerve cells die in Parkinson’s - Case
Studies
What are the faulty proteins doing
to cause nerve cells to die? Two studies were presented that examined the role
of two genes.
1. a-synuclein
When proteins are made the string of amino acids fold
around each other to form a 3D shape: the shape determines a protein's
function. Mutations have been found in the a-synuclein gene that cause
misfolding of a-synuclein protein. Misfolded protein sticks together to form
large cellular structures called Lewy bodies, leading to cell death and
Parkinson's.
The same process of DNA encoding proteins via RNA that
occurs in humans also occurs in flies (indeed in all living things). This makes
it possible to transplant a mutant form of the human a-synuclein gene into flies to
trick fly cells into making mutant a-synuclein protein. This causes
the formation of Lewy bodies, loss of nerve cells and Parkinson-like motor
impairment in flies. Interestingly, also producing normal human Rab11 protein
(involved in moving proteins to the cell surface) in these Parkinson's flies
dismantles the Lewy bodies, prevents nerve cell death and reverses some
Parkinson’s symptoms.
2. dj1
Mitochondria are structures within cells. They are the
power plants that produce all the energy needed by the cell. A toxic by-product
of energy manufacture is "reactive oxidative species" (ROS), a
chemical that can harm the cell. Nerve cells of the substantia nigra, which are
lost in Parkinson's, require lots of energy; therefore they produce lots of ROS
and are under "stress" to get rid of them before they damage the
cell. Damaged cells trigger apoptosis (or “programmed cell death” where cells
sacrifice themselves for the greater good) and die. A gene, dj1, helps the cell to
clean up ROS. Perhaps unsurprisingly, mutations in dj1 have been found in
Parkinson's sufferers; loss of dj1 function results in excessive
ROS-induced cell damage, apoptosis and cell death.
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