Cytokine messanger systems: slides 1-8

Question 1

When are cytokines usually in the body, and where?

Answer 1

when we are sick, in the bloodstream

Question 2

What two pathways do they utilize?

Answer 2

JAK-STAT and Ras-MAP

“janus kinase”

Question 3

JAK-stat signaling:

1) in cytokine signaling, how does this pw work?

Answer 3

1) cytokine binds to a homo/hetero dimeric receptor with janus kinases constitutively attached cytosolically
2) cytokine-receptor binding causes conformational change —> JAKs phosphorylate themselves

3) In turn, these phosphorylate the receptors
4) STAT proteins bind to phosphorylated receptor chains
5) JAKs phosphorylate the STATs
6) P-STATs form dimers and translocate/accumulate in nucleus where the regulate genes

Question 4

Cytokines: “critical” roles

Answer 4

1) inflammation
2) linking
3) activation of T cells (Th1)/Th2 polarization)
4) Activation of B cells (Isotype switching)
5) control of hematopoiesis

Question 5

Pleiotropic

Answer 5

cytokines exhibit multiple effects on growth and differentiation of a variety of cell types

Question 6

what are three general characteristics of cytokines?

Answer 6

1) redundancy (overlapping between cytokines)
2) synergy (act collectively to enhance their outcomes)
3) antagonism (blocks other cytokines)
4) cascade: one can induce another

Question 7

Example of a cascade (slide 8)

Activated Th – IFN-gamma –>

Answer 7

Macrophages – IL-12 –> Activated Th cells –> IL-2, IFN-gamma, TNF-beta, other cytokines