FINDING THE DISEASE GENES PROGRESS AND PROBLEMS

THE HUMAN GENOME MAPPING PROJECT SEEKS TO READ THE FULL SEQUENCE OF THE HUMAN GENOME 3 Billion bases so this is a huge task and uses DNA from blood cells Yeast Worms Flies Mice Other species are being analysed as well! Cell division/mitosis Cell death! Differentiation/patterns Mammalian studies

THE HUMAN GENOME MAPPING PROJECT 3 Billion bases in each cell Most of our DNA has no known function but 3% is divided into genes (30,000) transcribe translate RNA Protein

ALL CELLS HAVE THE SAME DNA!!! So, why do we have so many different cell types Different cells transcribe different sets of genes Skin cell Blood cell Brain cell ABCDEFGHIJ SAME GENOME, DIFFERENT TRANSCRIPTOME We can now start to define a fingerprint for each cell type - transcriptional profile

Transcriptional profiling by micro-array analysis Glass Slide In this way we can define the transcriptome of a cell!

IS ALL THIS INFORMATION HELPFUL IN CANCER RESEARCH? transcribe translate RNA Protein In cancer, the problem always occurs at the level of the genome -mutation (carcinogens!) -Inherited disorders -DNA breakage

IS ALL THIS INFORMATION HELPFUL IN CANCER RESEARCH? 1) Understanding the basic causes of cancer - In cancer the cell has become confused! Please do not put your hand in the fire Please do put your hand in the fire Please do drive carefully Please do not drive carefully A cancer causing gene??? Blood cell ABCDEFGHIJ Leukaemia cell

Micro-arrays help us to do this on a larger scale!

2) Finding new cancer causing genes in days rather than decades 3) Determining therapy? In some cancers, one individual may respond to treatment whilst another won’t Can we predict this using the new genetic information? 4) Designing new therapies New cancer genes mean new targets!

THE GENOME INFORMATION IS LIMITED IN ITS USEFULNESS! SO NOW WE ENTER THE POST-GENOME ERA

The Post-genomic initiatives 1) Determination of gene function AHYETONCGFPSOIUTEMOREOYELHQWBZCX AURELSANGHYALPONDONCEMOREYEMYRL OISGHWIYSPLAICMBZVTLESBROWNWOPANG AHYETONCGFPSOIUTEMOREOYELHQWBZCX AURELSANGHYALPONDONCEMOREYEMYRL OISGHWIYSPLAICMBZVTLESBROWNWOPANG JUST BECAUSE YOU CAN IDENTIFY A GENE DOESN’T MEAN THAT YOU KNOW WHAT IT DOES

TRANSGENICS IN CANCER RESEARCH How do we analyse the functions and role in disease for novel (or even known) genes? 1)In vitro analyses: OK but associated with artefacts 2)In vivo would be the ideal: can we generate animals that are either over-expressing the gene or that have it switched off?

To generate an animal with altered expression of a gene we really need to do this at the fertilised egg stage! Clearly this is a problem! Embryonal stem cells will help here ES cells Blood cells Cardiac muscle cells Neurons Skin cells Clinical potential here?

WE CAN GENETICALLY MANIPULATE THESE CELLS 1) Over expressing genes of interest (transgenesis) Inject into ES cells Generate mouse 1)Regulating expression is a problem 2)Insertional mutagenesis? 3)Lethality 4)Gene silencing PROBLEMS

TRANSGENESIS IS OF LIMITED USE BUT HAS SOME VALUE 1)Can mimic tumour formation and use animals to study therapeutics etc 2) Can humanise mouse models for disease studies 3) Eventually in higher animals can use to produce drugs or other therapeutically or biologically important proteins

SOMETIMES THE BEST WAY TO ANALYSE THE FUNCTION OF A GENE OR PROTEIN IS TO REMOVE IT AND SEE WHAT HAPPENS! This involves gene targeting or gene knockout technology

Can we genetically manipulate ES cells? 2) Removal of gene expression (knockout mouse generation) Altered RNA and non-functional protein

‘null’ ES cell‘null’ mouse Possible outcomes: 1)Embryo lethal 2)Post-natal lethal 3)No phenotype (redundancy???) 3) Is the worst case scenario. How far do you go to analyse these animals?

The Post-genomic initiatives 2) Determination of protein structure Crystal growth Diffraction pattern Crystal structure Without an understanding of protein structure the genome is meaningless!

Genome Transcriptome Proteome IEF SDS PAGE

Genome information: The hype! 1) The Book of Life? - don’t know the function of most genes - can’t yet use it to really understand proteins - can we use this information to understand life? 2) Genetic determinism? -there are probably too few genes 3) New cancer causing gene discovery (oncogenes) - in the short term more of a curse? 4) What does this mean for your life?

Genome information: The hype! 1) The Book of Life? - don’t know the function of most genes - can’t yet use it to really understand proteins - can we use this information to understand life? 2) Genetic determinism? -there are probably too few genes 3) New cancer causing gene discovery (oncogenes) - in the short term more of a curse? 4) What does this mean for your life?

ALL CELLS CONTAIN THE SAME DNA So, is it possible that a skin cell could become a blood cell? Could an adult cell become equivalent to a fertilised egg or an embryo?

ADULT CELL EGG CELL Discard nucleus Remove nucleus Fuse egg cell cytoplasm with adult nucleus IMPLANT INTO FEMALE ANIMAL ANIMAL CLONING

HOW MIGHT THIS TECHNOLOGY BE USEFUL? 1) Can address questions about aging 2) Can clone animals with useful traits 3) Can produce transgenic animals 4) Protection of endangered species 5) Cloning of extinct animals

CLONING TECHNOLOGY: THE PROBLEMS 1) What does this tell us about the legal/ethical status of an adult cell? 2) Reproductive cloning 3) Cloning for body parts 4) Cloning of a dead child 5) Generation of a human sub-class WHO SHOULD POLICE THIS?

IF CLONING FOR BODY PARTS IS BANNED ARE THERE OTHER WAYS WE CAN USE THESE CELLS TO PRODUCE TRANSPLANTABLE BODY PARTS? PERHAPS WE CAN DO THIS IN VITRO?

Embryonal stem cell Blood cells Heart cells Brain cells