17.5 Signaling Dynamics and Networks

Question 1

give an example of a feedback loop

Answer 1

regulation of NF-kappaB pathway:
- one of the target genes induced by NF-kappaB encodes I(kappa)B
- NF-kappaB signaling leads to I(kappa)B synthesis → inhibits continued NF-kappaB activity

Question 2

Explain how the dynamics of signaling can alter biological response

Answer 2

ERK signaling can lead either to cell proliferation or to neuronal differentiation depending on the duration of ERK activity
- transient (short duration) activation of ERK (~30-60 min) stimulates cell proliferation
- sustained activation of ERK for 2-3 hours induces differentiation of NGF-treated cells into neurons

Question 3

interaction of one signaling pathway with another → integrates the activities of different pathways within the cell

Answer 3

crosstalk

Question 4

example of pathways that do crosstalk

Answer 4

PI 3-kinase/Akt/mTORC1 and Ras/Raf/MEK/ERK pathways
- these 2 signaling pathways are activated downstream of tyrosine kinase receptors and play critical roles in the control of cell proliferation and survival
- crosstalk between the pathways involves both positive and negative points of regulation