The 2016 Prize in
Life Science & Medicine
Adrian P Bird,
Huda Y Zoghbi
for their discovery of the genes and the encoded proteins that recognize one chemical modification of the DNA of chromosomes that influences gene control as the basis of the developmental disorder Rett syndrome.
The Shaw Prize in Life Science and Medicine 2016 is awarded to Adrian P Bird and Huda Y Zoghbi for their discovery of the genes and the encoded proteins that recognize one chemical modification of the DNA of chromosomes that influences gene control as the basis of the developmental disorder Rett syndrome. Genes are turned on and off in a precise order to achieve the intricate balance needed for human development. This process is orchestrated by the recognition of landmarks on chromosomes, including some chemical modifications of the DNA and of proteins that bind to DNA that suppress or activate gene function. Adrian Bird discovered that one such chemical change, the attachment of a methyl group to the C residue in DNA, serves to mark some genes to be turned off whereas the absence of that methyl group allows genes to be turned on. His research uncovered chromosome-binding proteins that recognize the methylC to switch off gene function. In the 1990s, Bird discovered five different proteins that have this binding activity, one of which, MECP2, makes contact with an enzyme that removes an acetyl chemical tag from histones, a major chromosome structure-forming protein. These two tags, methylC in chromosomal DNA and the absence of acetyl groups on histones cooperate to reinforce an off signal on genes and contribute to the ‘epigenetic’ marking of genes. Working completely independently on a seemingly unrelated biological problem, Huda Zoghbi, a trained neurologist, made a surprising connection between one of Bird’s methylC binding proteins, MECP2, and a challenging neurological disorder, Rett syndrome.
Rett disease was first described by Andreas Rett in the 1966, as an X-linked disorder that manifests itself as lethality in males that have only one copy of the gene and as a distinctive but variable neurobehavioral disease in females that have one mutant copy of the gene. The disease affects approximately 1 in 10,000 girls who show normal development for 6 months to 18 months, but as the disease takes hold, they become withdrawn, regress in their mental development, exhibit compulsive behavior such as wringing of the hands, and eventually lose all purposeful use of the hands. Mutations in this gene are now known to cause a variety of neurologic disorders including bipolar disease and schizophrenia. In 1999, Zoghbi and colleagues discovered that mutations in MECP2 are the primary cause of Rett syndrome. Her discovery allowed a confusing set of symptoms to be turned into a straightforward diagnostic genetic test of the disease. The Zoghbi and Bird groups independently produced a genetic animal-mouse-model of the disease and showed that the creation of a brain specific genetic defect reproduced the major symptoms of the disease. The MECP2 protein is quite abundant in nerve cells, approaching the level of the major chromosome-binding histones; thus a change in the balance of the MECP2 protein is likely to have a profound effect on chromosome structure in disease patients. Zoghbi showed that some of the learning and memory symptoms could be treated with a form of deep brain stimulation that is used on patients with Parkinson’s Disease. In dramatic contrast to the irreversible damage associated with most neurologic disorders, Bird’s group showed that the animal model of Rett Syndrome could be restored to normal by reintroducing the active gene that codes for the missing methylC binding protein. This discovery suggests a path to treatment of certain neurologic disorders using the emerging technology of gene editing. These highly complementary studies show, once again, the power of basic science to uncover the fundamental basis of human development and disease.
An Essay on the Prize
The expression of genes is titrated precisely to achieve the proper balance of functions in all human tissues, including the brain. Ratcheting expression up or down is orchestrated by proteins that bind to DNA, leading to suppression or activation of gene function, but it also depends on signals left on chromosomes, including chemical modifications of the DNA itself. Adrian Bird devised a method for mapping one such chemical mark along chromosomes, namely the presence of a methyl group on the cytosine residue in DNA. This revealed a pattern of methylated and non-methylated sites that helps demarcate genes that can be switched on from those that are to remain silent. One way that this works emerged from his discovery in the 1990s of five different proteins that depend on methylation for their binding to DNA and can silence genes. One member of the protein family, MeCP2, recruits a large complex of enzymes that chemically alter chromosome marks by removing an acetyl chemical tag from a major structural component of the chromosome known as histones. The inter-connection of these two chemical features – the presence of methylcytosine in chromosomal DNA and the loss of acetyl groups on histones – establishes ‘epigenetic’ marking of chromosomal regions causing gene activity to be turned down.
The basic molecular mechanisms uncovered by Bird’s research acquired new significance through completely independent work on a seemingly unrelated biological problem. Huda Zoghbi, a pediatric neurologist studying genetic disorders associated with developmental delay and intellectual disability, made an unexpected connection between one of Bird’s methyl-cytosine-binding proteins, MeCP2, and a challenging neurological disorder called Rett syndrome.
Adrian P Bird
Adrian P Bird was born in 1947 in Wolverhampton, UK and is currently the Buchanan Professor of Genetics at the University of Edinburgh, UK. He obtained his Bachelor of Science in Biochemistry from the University of Sussex in 1970 and his PhD in Biochemistry from the University of Edinburgh in 1972. He was a Postdoctoral Fellow at the University of Yale and University of Zurich (1972–1975). He joined the MRC Mammalian Genome Unit (1975–1986) and then moved to Vienna, where he served as a Senior Scientist in the Research Institute for Molecular Pathology (1987–1990). He has held the Buchanan Chair of Genetics at the University of Edinburgh since 1990. He helped create the Wellcome Trust Centre for Cell Biology in Edinburgh and became its Director (1999–2011). Subsequently, he served as a Governor (2000–2010) of the Wellcome Trust including a term as Deputy Chairman (2007–2010). He is a Fellow of the Royal Society of London and Edinburgh and the Academy of Medical Sciences, UK.
31 May 2016 Hong Kong
Huda Y Zoghbi
Huda Y Zoghbi was born in 1954 in Beirut, Lebanon and is currently Professor of Pediatrics & Molecular and Human Genetics at Baylor College of Medicine, Director of Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital and an Investigator of the Howard Hughes Medical Institute, USA. She obtained her Bachelor of Science in Biology from American University of Beirut, Lebanon in 1975 and her MD from Meharry Medical College, Nashville, Tennessee, USA in 1979. She was a medical resident of Baylor College of Medicine and Texas Children’s Hospital (1979–1982) and then a Postdoctoral Fellow at Baylor College of Medicine (1982–1988). From 1988, she was successively Assistant Professor (1988–1991), Associate Professor (1991–1994) and Professor (1994–) in the Department of Pediatrics of Baylor College of Medicine. She has been elected to the US National Academy of Sciences and the National Academy of Medicine, USA.
31 May 2016 Hong Kong
"From DNA Methylation to Brain Function" by Professor Adrian P Bird
"Rett Syndrome: From the Clinic to Genomes, Epigenomes, and Neural Circuits" by Professor Huda Y Zoghbi