GV5: Inducible Transcription Factors

Question 1

what drives the gene transcription process

Answer 1

driven by availability/activation of transcription factors, accessibility of DNA, chromatin structure (DNA & histone proteins), requires coactivator proteins to unwind DNA

Question 2

what is histone acetylation

Answer 2

histone proteins have many basic amino acids with positive charge
enables interaction with negative phosphate backbone of DNA
acetylation blocks ability to bind DNA by masking positive charge
relaxes interaction of DNA with nucleosome

Question 3

what is heterochromatin

Answer 3

densely packed nucleosomes, condensed

not actively transcribed, deacetylated histones

Question 4

what is euchromatin

Answer 4

extended ‘beads on a string’ appearance

being actively transcribed, acetylated histones

Question 5

what does NFkB stand for

Answer 5

nuclear factor of Kappa (light chain) in B cells

Question 6

what is the role of NFkB

Answer 6

ubiquitous transcription factor, generally associated with the activation of inflammatory genes
all contain conserved sequence known as Rel domain which regulates dimerization and nuclear localisation
inhibited by IkB which binds across the Rel domain

Question 7

what activates NFkB

Answer 7

bacterial/viral infection
stress/UV/ROI
cytokines, IL-1, TNFalpha

Question 8

what is the process between NFkB and inflammation

Answer 8

free radicals IL-1 -> NFkB -> COX -> inflammatory prostaglandins

Question 9

what is AP-1

Answer 9

activator protein -1

Question 10

what does AP-1 do

Answer 10

regulates immediate early response genes, regulates a number of cellular functions including cell growth, compromises a dimer of the Fos and Jun families, requires transcription of Fos family member and phosphorylation of Jun family member

Question 11

what role does AP-1 have

Answer 11

regulates many genes involved in cell growth and differentiation
role in bone development and implicated in inflammation
may have a role in long term memory

Question 12

what happens in proliferation

Answer 12

cells are signalled to proliferate through the binding of growth factors to receptors
activation of intracellular signalling pathways leads to gene transcription
gene transcription results in the expression of proteins required to drive the cell through the cell cycle
process is tightly controlled to prevent aberrant proliferation

Question 13

what is the Go stage of the cell cycle

Answer 13

resting phase

Question 14

what is the G1 stage of cell cycle

Answer 14

Gap! - cell prepares for DNA synthesis

ensure it is large enough, has sufficient nutrients and all external growth stimuli are present

Question 15

what is the S-phase stage of cell cycle

Answer 15

DNA replicated/synthesised

Question 16

what is the G2 phase of the cell cycle

Answer 16

Gap2 - cells prepares for division

Question 17

what is the M-phase of the cell cycle

Answer 17

mitosis, spindle formation and cell division

Question 18

what are the two families of proteins involved in molecular basis of cell cycle control

Answer 18

cyclins (transcription dependent)
cyclin-dependent kinases (activation dependent)
phosphorylation by CDKs key in controlling cell cycle

Question 19

which cell cycle stage utilises cyclinD/CDK4/6

Answer 19

G1

Question 20

which cell cycle stage utilises cyclinE/CDK2

Answer 20

end of G1

Question 21

which cell cycle stage utilises cyclinA/CDK2

Answer 21

S

Question 22

which cell cycle utilises cyclinB/CDK1

Answer 22

G2

Question 23

what cyclins and CDKs are involved in cell cycle

Answer 23

growth factor stimulation, transcription of c-fos, activation of c-jun, transcription of cyclin D, cyclin D1 levels rise, cyclin D/CDK4 complexes, CDK4 phosphorylates pRb, pRb releases E2F, E2F active - required for transcription of cyclin E

Question 24

what are the two groups of CDK inhibitors

Answer 24

INK4 which inhibits CDK4/6

CIP/Kip which inhibits all CDKs

Question 25

what are CDK inhibitors used for

Answer 25

transcriptionally regulated, bind cyclin/cdk complexes to prevent activation, inhibits cell cycle leading to growth suppression, overall balance between cyclin/CDKs is important