December 19, 2010
In research published today, scientists have studied human brain samples to isolate a set of proteins that accounts for over 130 brain diseases. The paper also shows an intriguing link between diseases and the evolution of the human brain.
Brain diseases are the leading cause of medical disability in the developed world according to the World Health Organisation and the economic costs in the USA exceeds $300 billion.
The brain is the most complex organ in the body with millions of nerve cells connected by billions of synapses. Within each synapse is a set of proteins, which, like the components of an engine, bind together to build a molecular machine called the postsynaptic density – also known as the PSD. Although studies of animal synapses have indicated that the PSD could be important in human diseases and behaviour, surprisingly little was known about it in humans.
A team of scientists, led by Professor Seth Grant at the Wellcome Trust Sanger Institute and Edinburgh University, have extracted the PSDs from synapses of patients undergoing brain surgery and discovered their molecular components using a method known as proteomics. This revealed that 1461 proteins, each one encoded by a different gene, are found in human synapses. This has made it possible, for the first time, to systematically identify the diseases that affect human synapses and provides a new way to study the evolution of the brain and behaviour.
“We found that over 130 brain diseases involve the PSD – far more than expected,” says Professor Grant. “These diseases include common debilitating diseases such as Alzheimer’s disease, Parkinson’s disease and other neurodegenerative disorders as well as epilepsies and childhood developmental diseases including forms of autism and learning disability.”
“Our findings have shown that the human PSD is at centre stage of a large range of human diseases affecting many millions of people,” says Professor Grant.
“Rather than ’rounding up the usual suspects’, we now have a comprehensive molecular playlist of 1000 suspects,” says Professor Jeffrey L Noebels, Professor of Neurology, Neuroscience and Human Genetics at Baylor College of Medicine. “Every seventh protein in this line-up is involved in a known clinical disorder, and over half of them are repeat offenders. Mining the postsynaptic proteome now gives researchers a strategic entry point, and the rest of us a front row seat to witness neuroscience unravel the complexity of human brain disorders.”
The findings open several new paths toward tackling these diseases.