decoding NFKB

Question 1

What are NFKB proteins?

Answer 1

latent transcriptional regulators present in most animals. central mediators of immune and inflammatory responses

Question 2

what types of target genes do NFKB proteins regulate?

Answer 2

• cytokines: e.g. TNF-a, IL-1, IL-6
• ReI/IkB proteins: e.g. IkBa, c-rel, p105
• cyclins/growth factors: e.g. G-CSF, M-CSF
• regulators of apoptosis: e.g. Bc-XL, IAPs

Question 3

how many NFkB proteins are there in mammals?

Answer 3

5

Question 4

what do inhibitory proteins (IkBs) do?

Answer 4

bind to dimers, holding them in the inactive form when in the cytoplasm of unstimulated cells

Question 5

how is the effect of IkBs mediated when the cell is stimulated?

Answer 5

signals that release NFkB dimers trigger a signalling pathway which leads to phosphorylation, ubiquitylation, and consequent degradation of IkB proteins

Question 6

how is NFkB subject to regulation by a feedback loop?

Answer 6

NFkB activates the gene encoding IkBa, leading to increased synthesis of IkBa, this binds to NFkB, inhibiting it and creating a negative feedback loop