Jun 03, 2014 |
Molecular 'scaffold' could hold key to new dementia treatments
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(Nanowerk News) Researchers at King's College London have discovered how a molecular 'scaffold' which allows key parts of cells to interact, comes apart in dementia and motor neuron disease, revealing a potential new target for drug discovery.
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The study, published today in Nature Communications ("ER-mitochondria associations are regulated by the VAPB-PTPIP51 interaction and are disrupted by ALS/FTP-associated TDP-43"), was funded by the UK Medical Research Council, Wellcome Trust, Alzheimer's Research UK and the Motor Neurone Disease Association.
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Researchers looked at two components of cells: mitochondria, the cell 'power houses' which produce energy for the cell; and the endoplasmic reticulum (ER) which makes proteins and stores calcium for signalling processes in the cell. ER and mitochondria form close associations and these interactions enable a number of important cell functions. However the mechanism by which ER and mitochondria become linked has not, until now, been fully understood.
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Professor Chris Miller, from the Institute of Psychiatry at King's and lead author of the paper, says: "At the molecular level, many processes go wrong in dementia and motor neuron disease, and one of the puzzles we're faced with is whether there is a common pathway connecting these different processes. Our study suggests that the loosening of this 'scaffold' between the mitochondria and ER in the cell may be a key process in neurodegenerative diseases such as dementia or motor neuron disease."
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By studying cells in a dish, the researchers discovered that an ER protein called VAPB binds to a mitochondrial protein called PTPIP51, to form a 'scaffold' enabling ER and mitochondria to form close associations. In fact, by increasing the levels of VAPB and PTPIP51, mitochondria and ER re-organised themselves to form tighter bonds.
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Many of the cell's functions that are controlled by ER-mitochondria associations are disrupted in neurodegenerative diseases, so the researchers studied how the strength of this 'scaffold' was affected in these diseases. TPD-43 is a protein which is strongly linked to Amyotrophic Lateral Sclerosis (ALS, a form of motor neuron disease) and Fronto-Temporal Dementia (FTD, the second most common form of dementia), but exactly how the protein causes neurodegeneration is not properly understood.
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The researchers studied how TPD-43 affected mouse cells in a dish. They found that higher levels of TPD-43 resulted in a loosening of the scaffold which reduced ER-mitochondria bonds, affecting some important cellular functions that are linked to ALS and FTD.
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Professor Miller concludes: "Our findings are important in terms of advancing our understanding of basic biology, but may also provide a potential new target for developing new treatments for these devastating disorders."
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