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Immunology > Lec 4: Basics of Cell-to-Cell communication > Flashcards

Lec 4: Basics of Cell-to-Cell communication Flashcards

(50 cards)

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1
Q

How do immune cells communicate at a distance

A

Secretion fo proteins, hormones. Note here that concept of diffusion applies

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2
Q

Classes of Cytokine effects

A

soluble secreted proteins that act in an autocrine or paracrine manner

Pleiotrophy

Redundancy

Synergy

Antagonism

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3
Q

Pleiotrophy

A

induced varied responses in the target cell

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4
Q

Redundancy

A

different cytokines induce the same response

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5
Q

Synegry

A

cytokines cooperate in inducing a specific response

IFN for example (multiple can converge and boost a given signal)

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6
Q

Antagonism

A

cytokine blocks the activity of another cytokine

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7
Q

Why is the diversity of cytokine folds important

A

many conformations implies

different diffusion rates

different specificities

different regulators

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8
Q

what do cytokines depend on

A

transcription factors, signalling protiens present and epigenetic effects

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9
Q

why are cytokines benificial

A

for modulation of the immune response

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10
Q

Why is the redundancy of cytokines important

A

incase on cytokine does not work, we can maintain and immune response even with a partial loss

can boost a given signal (this is a synergistic effect and coordination)

cross talk

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11
Q

Why is antagonism important

A

what to dampen the signal at the end

also allows different tissues to react in different ways (reversal of immune response)

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12
Q

Can a single cytokine bind to multiple receptors

A

yes

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13
Q

what are the 5 classes of cytokine receptors

A

Ig-type ectodomain

TNF homotrimeric ectodomain

Cytokine Type 1 receptors (core ectodomain), can have other domains

Cytokine TYpe 2 receptors (core ectodomain), can have other domains

Chemokine receptors (typical and atypical)

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14
Q

Paracrine vs autocrine

A

Paracrine signaling: a cell targets a nearby cell (one not attached by gap junctions). The image shows a signaling molecule produced by one cell diffusing a short distance to a neighboring cell. Autocrine signaling: a cell targets itself, releasing a signal that can bind to receptors on its own surface.

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15
Q

Paracrine vs Autocrine

A

Paracrine signaling: a cell targets a nearby cell (one not attached by gap junctions). The image shows a signaling molecule produced by one cell diffusing a short distance to a neighboring cell. Autocrine signaling: a cell targets itself, releasing a signal that can bind to receptors on its own surface.

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16
Q

IL2 and IL15

A

IL2 and IL15 are essential cytokines mediating cell proliferation (IL2 is especially important in clonal expansion)

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17
Q

STAT5

A

STAT5 binds genes associated with cell proliferation, apoptosis, differentiation and inflamation

big driver of proliferation and apoptosis

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18
Q

How do antigen presenting cells change the flavour// activate a given T-cell

A

In this order

MHC
CO-stimulation (additional signal cascades)
Cytokine secretion

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19
Q

How are chemokines classified

A

divided into subfamilies on the basis of the presence of as conserved cysteine motif in their mature sequenses

are folded together by cysteine bridges

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20
Q

Pleiotrophic effects of chemokines

A

Extensive ligand promiscuity in the chemokine receptor family, and many chemokines can bind to multiple receptors

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21
Q

classes of chemokines

Study These Flashcards
A

C
CC
CXC
CX3C

see slides for diagram

22
Q

Typical chemokine receptors

Study These Flashcards
A

containing a seven-transmembrane domain

G protein-coupled chemotactic receptors

conserved DRYLAIV motif (AA sequence)

cell migration

23
Q

Atypical chemokine receptors (ACKRs)

Study These Flashcards
A

predicted seven transmembrane domain structure

do not signal through G proteins and lack chemotactic activity

substitutions in the DRYLAIV domain

Signalling via beta-arrestin leads to chemokine internalization

24
Q

What is the purpose of beta-arrestin signaling

Study These Flashcards
A

Signaling via beta-arrestin leads to chemokine internalization = ANTAGONISM

ligand scavenging and degredations

chemokine trafficking

control inflammatory and immune responses

25
nomenclature for typical chemokines receptors
CCL and CXCL
26
nomenclature for Atypical chemokines receptors
ACKR
27
how do atypical chemokine receptors help control infammation
they help to trap excess chemokine erythrocytes can act as a buffer for excess serum chemokines protection against excessive cytokine storms or chronic inflammation
28
Viruses can usurp cytokine signalling
some viruses encode protiens that mimic host cytokines, chemokines and their receptors Viral mimics do not have sequence similarity to host proteins, yet possess similar function
29
what do you notice about the types of chemokines herpesviruse mimics
immunosupression IL6 reduces the inflammatory response and chemokine signalling
30
Viralkines
Mimics cytokine, chemokine, or chemokine receptors interupt, mimic or distrupt host signalling cascades Ep-barr secretion of IL10 to suppress adaptive and innate immune responses
31
What kind of extracellular signals do cells use do communicate
Secretion of cytokines// proteins as well as hormones to induce immunocompetent (diffuses into cells) The can also secrete exosomes
32
Extracellular vesicles
delivery of bioactive macromolecules enclosed in a lipid bilayer, variable composition can enhance or supress immune activites
33
Why are extracellular vesicles so important when it comes to cell signalling
They contain a ton of information abot the cell that secreted them Surface markers, DNA, proteasome etc...
34
What are the two types of extracellular vesicles
exosomes and microvesicles
35
How does loss of integrety// secreation// membrane blebbing occur?
increase in temperature, and infection, toxins high osmotic stress etc
36
Necrosis// Necrotic Cell Death
aka cell lysis NOT apoptosis (dis is more violent) membrane rupture makes apoptotic blebbs which are little packets that may be degraded huge inflamatory response
37
Apoptotic bodies
Small little fragments to be eaten by macrophages Cell contents not released, no inflamatory response contain valuable information about the cells death
38
Biogeneisis of exosomes
A modified endosome, the intracellular components of these can be controlled Derived from MBV (multivesicular bodies) which fuse with the plasma membrane and release intraluminal vesicles as exosomes 30-100nm
39
Biogenesis of microvesicles
generated from budding from the plasma membrane lil scoops of a sample of the cytoplasm 30-2000nm
40
Dendridic cells and Extracellular vesicles
Dendritic cells may engulf important anitgens or signalling moleucles then secreate them in extracellular vesicles to a variety of immune cells may lead to inflammatory responses and or immune cell activation
41
Diffusion of PRR to other cell types
activation of other non-infected cells super important in exosomes
42
Exosome secretion during infection
exosomes containing antigens derived from pathogens can helpp activate the imune system through PAMPs and cross-priming DC antigen presentation also can have immunosuppressive effects
43
Group cytokines and chemokines based on their strucutre and receptors
Chemokines: cysteine bridges in 4 groups, C, CC, CXC and CX3C chemokines which can bind to either typical or atypical receptors. Chemokines exhibit extreme promiscuity when it comes to their receptors (they can often bind many) Cytokines: Conformationally very different which lead to variations of specificity, difffusion and regulation. They bind to 5 different types of receptors (Ig-type, TNF homotrimeric, Cytokine type 1, cytokine type 2, chemokine). Usually again, a given cytokine can bind multiple receptors
44
Compare and contrast the actions of cytokines and chemokines
A chemokine is a cytokine that specificaally induces motility towards a site of inflamation
45
Explain the importance of Cytokine-based communication in terms of pleiotrophy
here communication is important because pleiotrophy of target cell means different cells with respond differently to a given cytokine. This is due top variations of a cells given receptors, epigenetics, proteasome, transcription factors, and constituents of the signal transduction cascade
46
Explain the importance of Cytokine-based communication in terms of redundacy
Redundancy is important because just incase their is a mutation, or infection or simply the cell doesn't have a given receptor the end result will still get triggered issa good back up plan
47
Explain the importance of Cytokine-based communication in terms of Synergy
Coordination, and cooperation and crosstalk to boost signals for example, IFN signals boost each other
48
Explain the importance of Cytokine-based communication in terms of antagonism
Imporant when you want to silence a cascade before it gets out of control or simply because you dont what that signal in a given cell type or tissue
49
What is the importance of extracellular vesicles in immune communication and signalling
Allows a "controlled" diffusion of lysed cell components among the blood stream or lymph to activate immune cells (this is jsut one example = a dendritic cell). membrane vesicles give a good idea of what happened at a given site of infection.
50
MAPK
A mitogen-activated protein kinase is a type of protein kinase that is specific to the amino acids serine and threonine. MAPKs are involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflammatory cytokines

Immunology (23 decks)

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