Cell communication and signalling Flashcards
Learning Outcomes
- Define the terms cell communication, cell signalling, signal transduction
- List the different forms of cell communication
- Describe the mechanisms of G-protein coupled receptor (GPCR) signalling, and the role of G-proteins Explain what second messengers are, with examples such as cAMP
- Define the terms cell communication, cell signalling, signal transduction-List the different forms of cell communication-Describe the mechanisms of G-protein coupled receptor (GPCR) signalling, and the role of G-proteins
- Identify how Receptor Tyrosine kinase signalling functions, and the role of tyrosine phosphorylation
- Be able to name other forms of cell signalling such as steroid hormone andnitric oxide (NO) signalling
What are unicellular organisms signalling mechanism?
Use short peptides- responses are
Grow/divide
Die
Escape from immune cells
What substances do multicellular organisms signalling mechanisms use? Give examples
Use peptides, proteins, AA’s, nucleotides, steroids, retinoids, FA’s, gases (NO)
Can attract other cells, tell them to move away, to die, grow, divide
E.G hypoxia- cells release VEGF protein which causes blood vessel growth, leading to more oxygen supplied to organ.
E.G Knee jerk reflex- nerve/spinal signalling
E.G Neutrophil hunting bacteria
Examples of signalling molecules
See lecture 45 table
What is the difference between local and long distance cell signalling?
Local
- contact
- cell cell signalling
- Paracrine- cells in same vicinity
- Autocrine
- Synaptic
Long distance -Endocrine-hormonal e.g insulin, adrenaline, thyroid - Neuronal- short and long distance- diffusion of NT across synaptic cleft to target cell, LD as nerve body can be long distance from cleft e.g breathing phrenic nerve (neuron) and diaphragm (muscle cells, NM junction)
What is paracrine signalling?
Paracrine signaling: signaling in which the target cell is close to the signal releasing cell, and the signal chemical is broken down too quickly to be carried to other parts of the body.
example of Paracrine Signalling:
Insulin-like growth factor (IGF-1) signalling in Melanoma
Clotting agents in thrombus formation
Inflammatory mediators e.g. TNFa
What is autocrine signalling?
A form of signaling in which a cell secretes a chemical messenger that signals the same cell.
Examples of Autocrine Signaling:
-Cancer cells
-Interleukin-I (IL-1) in monocytes(immune)
-IL-2 signalingin T-cells
Describe the effect of insulin (endocrine signalling)
food >
increased blood glucose>
release of insulin from pancreas (islets of langerhans)>
insulin travels in blood to stimulate glucose uptake into blood, muscl, liver fat cells
How do cells achieve signalling?
Cells use specific receptors for cell signalling
- response of cells depends on what receptors it expresses
- same hormone can have different effects in different cells via the same receptor
- each receptor is specific for its own ligand(“lock and key”)
Describe the basic model of signal transduction
Signal transduction pathways:
basic model- membrane receptors allows hydrophyllic molecules to signal to the inside of the cell
-the signal is transduced from the
outside to the inside of a cell via intracellular signalling molecules
-the signal can be fast or slow in terms of the cell responses
Fast: adrenaline action on heart cells
Slow: insulin action on liver
What are the advantages of ST?
Signal transduction allows massive amplification of the signal- This means very low amounts of hormones, neurotransmitters can be effective in the body
E.G- reception of light
What are the different types of cellular receptors?
Plasma membrane bound 1. G-protein coupled receptors 2. Enzyme-linked receptors 3. Ion channel receptors Intracellular receptors 4. Steroid hormones Local signalling-gases Nitric oxide
Basic model of cell signalling from the plasma membrane
See lecture 45
Receptor > adaptor > effector
Receptors e.g ion channels, GPCR, receptor tyrosine kinase
Adaptors> adaptor proteins, scaffold proteins, molecular switches (messenger, amplifier and transducer proteins)
Effectors- responses ( proliferation, migration, apoptosis, transcription, glucose uptake etc.) primary messenger binds to receptor outside cell
- secondary messengers e.g cAMP brings about cellular responses
What are some drugs that target G protein coupled receptors (GCPR’s)?
- examples of drugs that target GPCRs:
- salbutamol (asthma)
- b-blockers (hypertension)
- serotonin-dopamine (L-DOPA)
- angiotensin II blockers
What are GCPRs?
G-protein Coupled Receptors (GPCRs)-GPCRs are proteins that span the membrane 7 times-1000s of GPCRs in the body, used by diverse ligands for rapid responses-examples: adrenaline, acetylcholine, dopamine, light, olfaction
-largest drug target family in the body-1000s of receptors controlling heart rate, vision, smell
