A3 cellular signalling pathways (spatial and temporal aspects)

Question 1

why do cells signal

Answer 1

coordination of day to day physiology

Question 2

why do cells signal at a cellular level

Answer 2

cells respond and change to stimuli in their environmeny
cell communication failure and impairment leads to disorder, disease and death

Question 3

what physiological activities rely on cell signaling

Answer 3

cell metabolism
cell growth
cell division
differentiation and development
coordination of gene expression
cell motility
cell morphology
cell death

Question 4

what are the two types of cell signalling

Answer 4

intercellular signalling
intracellular signalling

Question 5

explain intercellular signalling

Answer 5

communication between cells
-permits a single cell to influence the behaviour of other cells in a specific way
-synaptic transmission

Question 6

explain intracellular signaling

Answer 6

signalling within the cell
-responding to extra and intracellular stimuli

Question 7

what are intercellular signalling mechanisms

Answer 7

autocrine - cell targets itself
paracrine - a cell targets nearby cell
endocrine - cell targets distant cell through bloodstream
exocrine - acting on distant cell into a duct
juxtacrine - a cell targets a cell by gap junctions

Question 8

examples of the 5 intercellular signalling mechanisms

Answer 8

autocrine- immune response T lymphocytes can stimulate own proliferation
paracrine - neutrophils
endocrine - progesterone and testosterone
exocrine - sweat glands
juxtacrine - delta and notch signalling

Question 9

what intercellular signalling mechanisms does the liver use

Answer 9

endo and eco
insulin uses endo
bile uses exo

Question 10

what is required for intracellular signaling cascades

Answer 10

second messengers
protein kinases (phosphorylation)
signal convergence/ cross talk to lead to key cell fates

Question 11

what word is used to describe intracellular signaling cascades

Answer 11

network
its not linear, info and processes are received in many different complex ways

Question 12

what environmental cues are cells bombarded by

Answer 12

chemical
mechanical
electrical

Question 13

responses are intimately connected with what type of changes occurring within the 3D cell

Answer 13

spatially

Question 14

what are the 4 major type of cell signal receptor with example

Answer 14

1. ligand-gated ion channel receptors- nicotinic cholinergic
2. g protein-coupled receptors- beta-adrenergic receptors binding epinephrine
3. kinase linked receptors- insulin and growth factor
4. nuclear receptors- estrogen

Question 15

what does bias that exists with the extracellular signal, intracellular signal location impact

Answer 15

the kinetics of the response

Question 16

what can influence cell signalling

Answer 16

diff cell-cell ECM interactions
formation of lipid microdomains

Question 17

how can spatial and temporal dynamics be regulated

Answer 17

by physical barriers
eg cytoskeleton

Question 18

where is canonical GPCR signalling initiated at

Answer 18

plasma membrane

Question 19

can GPCRs be spatially (and temporally) compartmentalized

Answer 19

yes

Question 20

what are signalosomes

Answer 20

large supramolucular complexes
composed of unique combinations of signalling pathway components

Question 21

what are signalosomes targeted to and what do they allow cells

Answer 21

targeted to discreet intracellular localisation via the association of anchor or adptor proteins
allows cells to contruct the optimum cellular subdomain for sigalling

Question 22

what are caveolae

Answer 22

specialized membrane microdomains
that form invaginations in the plasma membrane

Question 23

what do caveolae function as

Answer 23

as platforms to recruit components of signal transduction pathways
and act as organising centres for signalling mols
sites of signal transduction

Question 24

high levels of what coat caveolins

Answer 24

cholesterol, sphingolipids, and protein

Question 25

GPCRs can generate unique signals from what

Answer 25

intracellular compartments

Question 26

after internalisation of GPCR what do some receptors do

Answer 26

remain active

Question 27

where are GPCRs internalised to

Answer 27

to endosomes and trafficked to pre golgi compartment

Question 28

thyroid stimulating hormone receptor elicits different outcomes depending on the duration of receptor stimulation- what are the outcomes

Answer 28

30s stimulation = transient cAMP increase
>2 min = sustained cAMP increase
additional specificity in response

Question 29

what is cAMP

Answer 29

a soluble second messenger and can freely diffuse in the cytosol

Question 30

how can GPCRs have different effects when they produce the same second messengers

Answer 30

prostaglandin and adrenalin

Question 31

what catalyses the breakdown of cAMP and how

Answer 31

phosphodiesterases (PDE)
by cleaving the P-O bond

Question 32

role of PDEs

Answer 32

as well as catalysing the breakdown on cAMP
limiting diffusion of cAMP in cytosol
subcellular localisation of PDEs can regulate cAMP dynamics

Question 33

what do measurable features of dynamic signals include

Answer 33

amplitude
frequency
duration
delay
cumulative level

Question 34

why is taking measurements at appropriate timescale crucial

Answer 34

to capture true dynamical behaviour

Question 35

timescale of the 4 intracellular receptors

Answer 35

1. ligand gated ion channels
   - milliseconds
2. GPCRs
   - seconds
3. kinase linked receptors
   -hours
4. nuclear receptors
   -hours/days

Question 36

what is compartmentalisation based on

Answer 36

expression of receptors and the intracellular memory