Label the molecular events (A-E) in the innate immune signaling pathway diagram

Question

Label the molecular events (A-E) in the innate immune signaling pathway diagram in an activated macrophage detecting and responding to an extracellular bacterium, below. What kind of bacterial molecule (A) does the cellular protein (B) recognize? What does this trigger (C)? What is transcription factor activated in (D)? What are gene(s) expressed in (E)? Which cytokines from the list below might be released from macrophages activated by the innate immune pathway in question#1? (Circle all that apply). IL10 Complement c5a IL1 beta Interferon-Y (IFN-gamma) F. IL12 Immunoglobulin M (IgM)

Explanation / Answer

This question has multiple quiestion. The asker did not specify which of the two qustions to be answerted. As per Chegg's policy, I am answering the first question.

Answer to the first question

Bacterial molecule (A) can be peptidoglycan layer of Gram+ve bacteria or lipopolysaccharide (endotoxin) in the outer membrane of Gram-negative bacteria or flagellin of some motile bacteria.

These bacterail molecules are recognized by cell surface receptors ("B" as per te question) called Toll like receptors (TLRs). There are different types of TLRs. Each type of baterial molecule is recognized by a specific type of TLR.

If bacterial molecule ("A" as per the question) is peptidoglycan layer of Gram+ve bacteria, it will be bound by TLR-2. If "A" is lipopolysaccharide (endotoxin) in the outer membrane of Gram-negative, "B" will be TLR4. If "A" is flagellin, then "B" will be TLR5.

Now we will see what "C" in the question Can be.

What ever the TLR type gets active in the above stage, It triggers similar downstream signaling processes. First, Myd88 and IL-1R-associated kinase 4 (IRAK-4) and IRAK-1 are recruited to cytoplasmic domain of TLRs, Then IRAKs will be activated by phosphorylation which inturn activate TRAF6. TRAF6 activates transforming growth factor --activating kinase 1 (TAK1) which inturn phosphorylates IKK-b and MAP kinase kinase 6 (MKK 6). This leads to degradation of I-B triggering nuclear translocation of NFkB transcription factor.

So, the molecule "C" as per the question is any of the above molecules(MyD88/IRAKs/TRAF6/TAK1/IKK-b/MKK6).

the transcription factor becoming active and translocating to nucleaus in this case is NFkappaB. So, the molecule "D" as per the questiuon is NFkB.

NfkB in nucleas induce the transcription of genes like TNF, Cox2 and IL18. These there can be Molecule "E" in the question.

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