Mod 1 dominant negative mutations

Question 1

Dominant negative mutation

Answer 1

Mt, gene product negatively affects function of wt gene product - perhaps losing function (deleterious effect)

Usually occurs with proteins that dimerise with others/form complexes with other proteins - more severe than homozygous loss of function

Question 2

DNMT, TRbeta and THRS

Answer 2

TH = important regulator of growth, heart contractility, nervous system differentiation, metabolic rate
RTH = dominantly inherited disorder, elevated T3/T4, TSH

Question 3

Experiment

Answer 3

DNA that TRB binds to.
TRE = TH response element, upstream of luciferase reporter, transfect into wt, empty and mt
Mt rc has lower activity than empty - dominant negative

Question 4

CoA recruitment

Answer 4

WT: Activation of TRB by TH facilitates action between CoA peptide fused between DBD and NR = increase luciferase activity

MT: small (insignificant increase) - MT in LBD has impaired the ability of rc to bind with CoA

Question 5

CoR recruitment

Answer 5

Used CoA AD

WT: no hormone, interacts strongly with CoA. With hormone, NR boots off CoR and binds with CoA

MT: strong interaction but can’t boot off CoR, interacts with it but when hormone present, either rc doesn’t interact or it is but has impaired ability to move H12 helix inwards to remove CoR - doesn’t react with CoA

Question 6

NR4A

Answer 6

Nurr77, Nurr1, NOR1
Immediate early response genes - respond very rapidly and expression changes and fluxes wildly in response to other signals
Expressed in different cells, responds to GFs and mitogenic signals

Question 7

Functions of NR4A

Answer 7

Protects neuronal cells from oxidative stress
Co-ordination of metabolism in skm, adipose, and liver
Induced by inflammatory mediators in macrophage

Question 8

MC1R

Answer 8

GPCR, NB in regulating pigmentation.
DNA repair process, increases repair of CPDs, decreased apoptosis and ROS

Homozygous: red hair, fair skin, UV sensitivity, increased melanoma risk

Question 9

Glucocorticoid receptor

Answer 9

NFkb: pro-inflammatory TFs, responds to inflammatory signals and activates gene - must be controlled
GR binds to NFkb and blocks interaction with pro-inflammatory TFs

GR + fos/jun = recruits GRIP (CoA) - has repression domain, becomes activated and turns off transcriptional response
Binds via NTRIP6

Protein-protein interaction, uses others to bind to DNA (NFkb)