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

YeastWormsFliesMice

Other species are being analysed as well!

Cell division/mitosisCell death!Differentiation/patternsMammalian 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

A B C D E F G H I J

SAME GENOME, DIFFERENT TRANSCRIPTOME

We can now start to define a fingerprint for each celltype - 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 firePlease do put your hand in the fire

Please do drive carefullyPlease do not drive carefully

A cancer causing gene???

Blood cell

A B C D E F G H I J

Leukaemia cell

Normal Cell Cancer 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 treatmentwhilst 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

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AHYETONCGFPSOIUTEMOREOYELHQWBZCXAURELSANGHYALPONDONCEMOREYEMYRLOISGHWIYSPLAICMBZVTLESBROWNWOPANG

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 fornovel (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 thathave it switched off?

To generate an animal with altered expression of a genewe really need to do this at the fertilised egg stage!

Clearly this is a problem!

Embryonal stem cells will help here

ES cells Blood cellsCardiac muscle cellsNeuronsSkin 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 problem2) Insertional mutagenesis?3) Lethality4) Gene silencing

PROBLEMS

TRANSGENESIS IS OF LIMITED USE BUT HAS SOME VALUE

1) Can mimic tumour formation and use animals to studytherapeutics etc

2) Can humanise mouse models for disease studies

3) Eventually in higher animals can use to produce drugs orother 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 lethal2) Post-natal lethal3) 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

Crystalgrowth

Diffractionpattern

Crystalstructure

Without an understanding of protein structure the genome is meaningless!

Genome

Transcriptome

Proteome

IEF

SDSPAGE

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 CELLEGG CELL

Discardnucleus

RemovenucleusFuse 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 ofan 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 BANNEDARE 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