transcriptional Regulation

what is Eukaryotic gene regulation

• Controlled expression of a gene in a temporal and spatial manner

• Imp for specialised cell function

ensuring that the right genes are expressed at the right times and in the right cells

what is the most common mechanism for regulation of gene expression

transcriptional regulation

what is transcription

• DNA into single stranded RNA

what is involved in transcription

• dna template

• enzymes

• rna nucleotides

• protein help

what are promoters

proteins that initiate transcription of that gene

composed of sets of conserved DNA sequences

• make sure RNA polymerase is in the right gene at the right time → steer RNA polymerase when it is right

what are 4 promoter regions

1. enhancer

2. upstream elements

3. TATA box

what is the enhancer region

• Thousands of bases away from the start of the gene

• Help RNA polymerase work much more efficiently + increase transcription

What is the TATA box

• The sequence of Adenosines and Thymines = stabilise and encourage RNA activity

• Found in promoter region- RNA binds with it

• Conserved through generations.

• Specifies to other molecules where transcription can begin

how is gene transcription activated?

driven by the activation of Transcription Factors

+ accessibility of DNA

+chromatin structure

+requires COACTIVATOR PROTEINS to unwind DNA

what type of proteins unwind DNA

Co-activator proteins → promoting chromatin decondensation and activation of the gene expression.

why does DNA change its chromatin structure

to get access to one part of the DNA we want that encodes for a protein we want to make

two chromatin structures

• heterochromatin : densely packed, no transcribing

• euchromatin: actively transcribed, loosely packed

what is histone acetylation

neutralises positive charge of heterochromatin and converts it to euchromatin to allow for easier gene transcription

by which mechanism does DNA wind back to heterchromatin

histone de-acety transferase (HDATs)

how does transcription occur

1. EGF binds to EGFR

2. Activation of the intracellular pathway (kinases..)

3. Activation of transcription factors

4. co-activator proteins

5. unwinding of DNA in the enhancer region

6. binding of TF

7. looping of DNA

8. unwinding DNA upstream region

9. constitutive factors bind to the CAAT/GC box

10. looping of DNA

11. co-activator enhances the binding of TBP to TATA

12. activation of RNA polymerase 2

13. unwinding of DNA and reading 3’ to 5’ strand

14. synthesis of mRNA 5’ to 3’

which transciption factor has been implicated in several cancers

N-Myc

changes in DNA accessibility is altered in alot of diseased states