1. Identification of common factors regulating suspected gene battery
PRESENT:
AMIR RUBINSTEIN
LIA MITTELMAN

2. Cancer throughout the animal kingdom
Tumors or neoplasms occur throughout the animal
kingdom,from the most primitive matazoa to vertebrates.
The risk of cancer might be an unavoidable price to pay
for the evolution of multicellularity.
A fine balance between neoplasms
cell proliferation + cell death (cancer)

3. Genes and cancer 2. tumor suppressors
Cancer as a genetic disease, may arise from
defects in positive and negative regulators of
cell proliferation:
1. oncogenes
2. tumor suppressors

4. Tumor suppressors and oncogenes

5. Brain tumor suppresors in drosophila
1.brat
2.mbt
3.lgl
4.dlg
Mutants neuroblasts fail to differentiate cotinue to proliferate brain tumor

6. A common pathway? Common binding sites for transcription factors (“promoter”)?
Dlg, Lgl, Mbt, Brat
identical phenotype
Pathway not yet known.

7. Regulation of Transcription in Eukaryotes
The genes of eukaryotes tend to be larger:
Regulatory sequences on the DNA can be located tens of thousands of base pairs away from the transcription start site .
A battery of regulatory factors is sometimes needed for proper regulation of certain genes.

8. Regulation of Transcription in eukaryotes relies on two general classes of cis-acting sequence elements
1. Core promoters

9. 2. Enhancers / Silencers
Elements in DNA that are recognized by TRANSCRIPTION FACTORS
Enhancers can be located Kbp away from the core promoter!
Enhancers are orientation- and position-independent, they may be upstream, downstream, or within a gene.

10. Observations about “promoter” elements
1. Individual elements may be present in many copies. Only the TATA box is limited to one.  
2. No element is essential !
3. Only the TATA box displays a conserved position relative to the transcriptional start site.
  Other sequences are orientation and position independent.
4.  Transcription factors further regulate levels of expression.

11. Databases FlyBase Database of genetic and molecular data on all
species from the family Drosophilidae.
The primary species represented is
Drosophila melanogaster.

12. …Databases Transfac Transcription factor database.
Searches for potential transcription factor binding
sites.
DNA sequence regulatory seq.
in DNA
TRANSFAC

13. Analysis - Part 1 We got 1000 bp upstream of each of our 4 genes.
-1000

14. Analysis - Part 2 Brat lgl 4 DNA sequences mbt dlg regulatory
seq. in DNA
How will similarity look in the results ?
We needed something to compare with.
Brat
lgl
mbt
dlg
TRANSFAC

15. “Getting started with something we know”
Heat-Shock genes
Hsp22 hsp hsp68
3 genes that are known to have a role in the same biochemical pathway (“gene battery”).
They are expressed in stress caused by extreme temperatures.
It is known that these genes have at least 1 common DNA binding site for transcription factor, and its sequence is already known.

16. So this is similarity!
Heat-shock genes family

17. Analysis - Part 3 Now we are ready to check our genes.
Here are the results...

18. Tumor suppressor genes in Drosophila

19. Explanations Elements of uncertainty in our results:
Regulatory sequences appear also downstream (to the 3’ direction after the gene), inside the gene (where introns are found), and further upstream
The context in which the short promoter is located within, effects a lot its functionality.
So does the 3D structure of the DNA in that area, and the electric distribution of atoms. Far away areas of DNA may fold and effect other areas.

20. …Explanations Regulatory areas are rich of A’s and T’s.
The probability to find a short sequence like AAAT is higher than usual. Some of the “promoters” we found looked like that.
Arithmetical manipulation on the results was too simple.
We can blame the database.
We don’t know whether our 4 genes really act in a common pathway.

21. Goals for the future…
1. REPORTER GENE TECHNIQUES CAN BE USED TO ISOLATE INDIVIDUAL REGULATORY ELEMENTS OF GENES.

22. Goals for the future…
2. MICROARRAYS-DNA CHIPS

23. Thank you for listening !