Lecture 5 Flashcards
what type of receptors do cytokines signal thru?
signal via HETERODIMERIC receptors
describe the activation of cytokine receptors (4 steps)
- cytokine binding allows for dimerization
- each subunit has kinase domain that phosphorylates opposite subunit
- more phosphorylation allows for more STAT phosphorylation
- STATs dimerize and go to nucleus to drive transcription
how is cytokine receptor signaling different than PRR signaling?
PRRs usually monomers, cytokine receptors are heterodimers
what is the common gamma chain?
common subunit for many cytokine receptors
describe the 2 subunits of cytokine receptors
1 is common gamma chain, 1 is subunit specific to cytokine
2 ways that specificity is achieved with cytokine signaling
- unique subunit
- heterodimerization of diff STATs
describe how heterodimerization of STATs allows for specificity with cytokine signaling
many cytokines can signal through the same STAT protein but diff combinations of STAT dimers allows specific downstream signaling
explain IL-2 signaling vs IL-7 signaling
both signal via receptor via common gamma chain + IL-2 or IL-7 specific subunit
both signal thru same JAK kinases
both use STAT5 but heterodimerize with diff STATs
why is it important that cytokine signaling has specificity? use IL2 vs IL7 as example
for example, IL2 and IL7 are important for lymphocyte growth but at different times so receptors are expressed at different times
to identify the unknown lineage negative cells from last lecture, why is it helpful to see if they respond to common gamma chain cytokines?
lymphocytes respond to cytokines bc their cytokine receptors have the common gamma chain –> so interesting to see if these unknown cells can also respond like T cells
what happens if you put T cells in a dish with IL-2?
IL-2 is lymphocyte development cytokine –> will proliferate and differentiate
what happens if you put the unknown cells in a dish with IL-2?
cells are responding to the cytokine –> PROLIFERATING but not differentiating into lineage and maintaining stem cell-like markers
explain these results, one column at a time
IL-2
- growing but not making cytokines
IL-2 + IL-25
- making IL5 and IL13, not IFNy
IL-33
- making IL5 and IL13, not IFNy
Th1 and Th2 are positive controls
what is the significance of these unknown cells being able to produce IL5 and IL13? how do we know?
must be INNATE-LIKE LYMPHOID cells bc they are making Type 2 cytokines, IL5 and IL13
but they are NOT T cells bc T cells require APC and antigen to activate, but these cells could activate with only cytokines (a property of innate cells)
what do these data show? conclusion?
(Rag KO = cant make TCR/BCR)
Stimulating cells with IL33:
- In Rag KO: lots of IL5 and IL13
- In Rag and gamma chain KO: no IL5 or IL13 produced
therefore, when stimulated must respond via gamma chain to produce IL5 and IL13
what do these images show? significance?
injecting with IL33 allows for production of goblet cells in rag KO but not rag and gamma chain KO mice
significant bc goblet cells can only be made when IL13 is produced
what is the INDIRECT evidence that these unknown cells are the cells that produce IL13? why is this only indirect evidence?
stimulating Rag KO mice with IL33 allows production of IL13 and goblet cells (stimulated by IL13)
this is INDIRECT bc maybe other cells that make IL13 are also being knocked out, we’re not directly looking at the cells of interest
what do these data show?
instead of injecting IL33, infect mouse with Nippo worm
WT and Rag KO similarly produce IL5 and IL13 (therefore Rag not necessary for function, therefore not lymphocyte)
Gamma chain and Rag KO has no IL5 or IL13 production
how can we show direct evidence of ILC2 function?
instead of using IL33 alarmin cytokine to stimulate cells, actually infect the mouse with Nippo worm bc more physiologically relevant
what did they do after showing that Nippo worm infection stimulates cytokine production in WT and Rag KO mice but not in gamma chain and Rag KO mice? what did they find?
transfer the ILC2s to infected gamma chain and Rag KO mice
infected mice who received the ILC2s produced IL13 and more goblet cells
what is the direct evidence of these unknown cells producing IL13?
when there is a worm infection, the unknown cells are sufficient to drive the response and make IL13 and therefore goblet cells
describe the ILC lineage (4 stages)
- common lymphoid progenitor
- diff signals allow for diff cells to be produced but all require GATA3
- Become ILC precursor in bone marrow
- diff cytokine signals promote differentiation
describe the common lymphoid progenitor
lives in bone marrow and gives rise to all lymphoid cells and ILCs
are ILCs tissue-resident?
yes, they are tissue-resident cells of lymphoid origin
