Mid 2: Lec 11

Question 1

4 styles of mirna regulation

Answer 1

The basic approach:
single microRNA–mRNA
Interactions

Broad effects: one
microRNA to many mRNAs

The functional approach
to regulation

The pathway-based
approach to regulation

Question 2

miR-372 and miR-373

Answer 2

Following Hippo signalling , large tumour
suppressor (LATS) phosphorylates and inhibits YAP and TAZ; this is prevented by high levels of miR-372 and miR-373, which target LATS

Question 3

miR 125b

Answer 3

example of a miRNA operating as a primary mediator of default repression.

In a normal cell miR-125b targets residual p53 activity, avoiding apoptosis. Following
genotoxic inputs p53 is activated and miR-125b is repressed, inducing apoptosis.

Question 4

let-7 miRNA differentiation

Answer 4

example of microRNAs and signaling gradients

let-7 expression increases during differentiation, resulting in
progressive inhibition of RAS signalling. This enables self-renewal in progenitor cells but restrains it while cells differentiate.

Question 5

miRNAs in bistable fate choices

Answer 5

n a cell, a transcription factor
(TF) inhibits the expression of a miRNA; in turn, the miRNA inhibits expression of the TF. The cell can adopt two alternative
fates: state A is the default fate, in which miRNA expression dominates and the expression of the TF is turned off. In state B,
an extrinsic cue (signal) stabilizes the TF, promoting cell differentiation and leading to repression of the miRNA and give a
different cellular outcome

Question 6

microRNAs and cancer

Answer 6

oncogenes or tumor suppressors

Question 7

miR 21

Answer 7

oncogenic miRNA

Question 8

Restoring microRNA levels as cancer treatment inc specific mirna

Answer 8

synthetic oligonucleotides to mimic miR-34

reduces tumor growth

Question 9

blocking mi rna as therapy

Answer 9

antisense oligonucleotides