miRNAs and Developmental Canalisation Flashcards
1
Q
Canalisation
A
“Robustness”
2
Q
How many genes are in the human genome?
A
- urban myth = 100,000 (actually c40,000)
- 21,306
3
Q
Why approximate?
A
Counting conundra
- pseudogenes
- small ORFs
4
Q
Genes produce functional
A
ncRNA (>20,000)
5
Q
HOTAIR
A
- long ncRNA
- several one
- recruits H3K27me3 on Hox
6
Q
HOTTIP
A
- long ncRNA
- several kb
- recruits H3K4me3 on Hox
7
Q
miRNAs
A
- c22nt
- 100s/1000s / species
- vibe mRNA
8
Q
miRNA cleavage
A
- in plants and animals
- perfect match
9
Q
MiRNA blockage
A
- animals
- approximate match
10
Q
miRNA summary
A
1) miRNA transcription
2) folds into c70nt pri-miRNA hairpin
3) Drosher and Pasha: pre-miRNA
4) nuclear export
5) DICER
6) RISC complex takes up strand
11
Q
Why use miRNAs for I regulate gene activity during development?
A
- faster than transcriptional control
- RNA half-life; temporary, highly localised control
12
Q
Paradoxical miRNA findings
A
- some are highly conserved
- v. few are lethal mutants
13
Q
Finding the targets:
A
- Sequence matches (3’UTR) ; false hits
- Introduction (look for <RNA) ; indirect effects
14
Q
Human miRNA introduction in HeLa cancer cells
A
- muscle expressed miRNA1 suppresses no muscle genes
- brain expressed miRNA124 suppresses non-brain genes
- microarray; c100 genes go down for each miRNA
15
Q
miRNA non cell-autonomous behaviour
A
Weed out stochastic / polymerase / chromatin errors
