Important molecules Flashcards
Caspase 1
- Cleaves pro-IL-1β into IL-1β
- Cleaves pro-IL-18 into IL-18
- Cleaves Gasdermin D, which then enters the plasma membrane and creates a pore for the exit of IL-1β and IL-18 as well as promoting pyroptosis (lytic form of cell death)
Caspase 3
- Granzymes cleave pro-caspase-3 into caspase 3
- Caspase 3 cleaves ICAD forming CAD
- CAD cleaves DNA - cell death induced
Caspase 9
- BID cleaved by granzymes
- Truncated BID disrupts MOM
- Cytochrome C released
- Caspase 9 activated
- DNA cleavage - cell death induced
E3 ligases: what are they, what do they do, and what are some examples, and what signalling pathways are they involved in?
Enzymes that form protein scaffolds to allow for binding of molecules used in signalling pathways
- XIAP (X-linked inhibitor of apoptosis protein) - used in the NLR signalling pathway
- cIAP1 (cellular inhibitor of apoptosis 1) - used in the NLR signalling pathway
- cIAP2 (cellular inhibitor of apoptosis 2) - used in the NLR signalling pathway
- Riplet - used in the TLR signalling pathway
- TRIM25 (Tripartite Motif Containing 25) - used in the TLR signalling pathway
Endogenous pyrogens: what does it mean, what are some examples, what systems are affected by them, and what do they cause?
Cytokines that promote fever
TNF-α, IL-6, IL-1β, etc
- Liver - acute-phase proteins, c-reactive protein, mannose binding lectin - activation of complement (opsonisation)
- Bone marrow - neutrophil mobilisation - phagocytosis of pathogens
- Hypothalamus - increased body temperature - decreased pathogen replication and increased antigen processing/adaptive immune response
- Fat and muscle - increased metabolism, increasing temperature - decreased pathogen replication and increased antigen processing/adaptive immune response
- Dendritic cells - TNF-α stimulates dendritic migration to lymph nodes and maturation (initiation of adaptive immune response)
NFκB
Nuclear factor-kappa B - a transcription factor
Produced through PRR signalling pathways - Promotes the production of cytokines and other antibacterial molecules
Produced by signalling induced by the interaction between the TcR and MHC - promotes production of cytokines (ie IL-2)
Gasdermin D
Cleaved by caspase 1 and then enters the plasma membrane and creates a pore for the exit of IL-1β and IL-18 as well as promoting pyroptosis (lytic form of cell death)
S1PR1
Shingosine 1 phosphate receptor 1
Promotes exit of mature thymocytes toward high concentration of S1P in blood
P-selectin glycoprotein ligand 1
Binds P/E selecting, expressed on activated epithelium
CR2
Complement receptor 2 (CD21)
Found on marginal zone B-2 B-cells
Respond to circulating complement proteins in the blood
CCL2
C-C motif ligand
Directly recruits monocytes
CCR4
C-C chemokine receptor type 4
Expressed on Th2 cells
CCR5
C-C chemokine receptor type 5
Expressed on Th1 cells and monocytes
CCR6
C-C chemokine receptor type 6
Expressed on Th17 cells
CCR7
C-C chemokine receptor type 7
Ligand on recent thymic emigrates that promotes movement to secondary lymph tissues for further development
Also on any cells like DCs that are moving to secondary lymph tissues
CRTH2
Chemoattractant receptor-homologous molecule expressed on T helper type 2 (Th2) cells
Expressed on Th2 cells
CTLA-4
Cytotoxic T-lymphocyte-associated protein 4
Binds to CD80/86 with higher affinity than CD28, rips t-cells off of dendritic cells
Granzymes
Induce cell death through either to CAD or BID pathways
(i)CAD
(Inhibitor of) caspase-activated DNase
Part of the pro-caspase-3 pathway
Cleaves DNA, causing DNA damage and inducing cell death
BID
BH3 Interacting Domain Death Agonist
Granzymes induce its production
- BID cleaved by granzymes
- Truncated BID disrupts mitochondrial outer membrane
- Cytochrome C released
- Caspase 9 activated
- DNA cleavage - cell death induced
CD4
Cluster of Differentiation 4
Part of the TcR in the CD4 subset of T-cells
CD8
Cluster of Differentiation 8
Part of the TcR in the CD4 subset of T-cells
CD21
Cluster of Differentiation 21 (CR2)
Found on marginal zone B-2 B-cells
Respond to circulating complement proteins in the blood
CD25
Cluster of Differentiation 25
Part of the TcR in Foxp3+ Tregs, high-affinity IL2R, IL-2 binding causes differentiation into a Foxp3 Treg in the two-step model of Thymus Treg development
CD28
Cluster of Differentiation 28
A costimulatory molecule on T-cells that causes T-cell activation after interaction with CD80/86
CD36
Recognises lipids and lipoproteins such as LPS
- Bacteria
Complement proteins: what are they and what do they do?
- C1q - Binds to pathogen, activation of C1r
- C1r - Cleaves C1s into active form
- C1s - Cleaves C4 and C2
- C4a - Weak mediator of inflammation
- C4b - Binds C2 for C1s cleavage, covalently binds pathogen and opsonises it
- C2a - Cleaves C3 and C5
- C2b - Precursor of vasoactive C2 kinin
- C3a - Promotes inflammation
- C3b - Binds C5 for C2b cleavage, initiates amplification for the alternative pathway, many molecules of it bind to pathogen to opsonise it
- C4b2a - C3 convertase, cleaves C3 into C3a and C3b
- C3bBb - C3 convertase, cleaves C3 into C3a and C3b
- C4b2a3b - C5 convertase, cleaves C5 into C5a and C5b
- C3bBb3b - C5 convertase, cleaves C5 into C5a and C5b
- C5a - Promotes inflammation
- C5b - forms a trimer with C6/C7
- C5b67 - binds C8
- C5b678 - binds C9 molecules and forms the membrane attack complex
Regulators of the CLA complement pathways: what are they and what do they do?
- FHRs - Factor-H related proteins, form iC3b (FH/FHL-1, MCP, CR1, etc)
- Properdin - stabilises C3bBb
- Factor I - cleaves C3b into iC3b
- C1inh - inhibits C1
- DAF - Accelerates the decay of C3 and C5 convertases
- CR1 - Accelerates the decay of C3 and C5 convertases
- Clusterin/vitronectin - inhibit the addition of C8 from the C5/6/7 trimer
- CD59 - inhibit C9
CR proteins: what are they, what are the types, what do they bind, what do they do, and what cells are they found in?
Complement receptor proteins
- CR1 (CD35) - C3b/C4bi - promotes C3b and C4b decay, stimulates phagocytosis (requires C5a), erythrocyte transport of immune complexes - erythrocytes, macrophages, monocytes, PMN leukocytes, B cells, FDC
- CR2 (CD21) - C3d/iC3b/C3dg - part of B-cell co-receptor, enhances B-cell response to antigens bearing C3d/iC3b/C3dg Epstein-barr virus receptor - marginal zone B-2 B-cells, FDC
- CR3 (CD11b:CD18 heterodimer/Mac-1) - iC3b - stimulates phagocytes - macrophages, monocytes, PMN leukocytes, FDC
- CR4 (CD11c:CD18 heterodimer/gp150, gp95) - iC3b - stimulates phagocytes - macrophages, monocytes, PMN leukocytes, dendritic cells
- CRIg - C3b/iC3b - phagocytosis of circulating pathogens - tissue-resident macrophages, hepatic sinusoid macrophages
CD27
Cluster of Differentiation 27
Costimulatory molecule found on memory cells
CD40
Cluster of Differentiation 40
A costimulatory molecule on DCs that causes t-cell activation after interaction with CD40L
CD40L
Cluster of Differentiation 40 ligand
A costimulatory molecule on T-cells that causes T-cell activation after interaction with CD40
CD45
Cluster of Differentiation 45
Involved in the dephosphorylation of ITAMs
Gets subjected to being in the dSMAC during SMAC formation
CD62L
Cluster of Differentiation 62 ligand
Ligand on recent thymic emigrates that promotes movement to secondary lymph tissues for further development
CD80
Cluster of Differentiation 80 - B7
A costimulatory molecule on DCs that causes t-cell activation after interaction with CD28
CD86
Cluster of Differentiation 86 - B7
A costimulatory molecule on DCs that causes t-cell activation after interaction with CD28
CXCL2
Chemokine ligand 2
Produced by cells reacting to IL-17 (Th17 cells)
Promotes neutrophil recruitment