Lecture 2 Cell-derived signalling molecules

Question 1

What are the types of secretion routes for proteins?

Answer 1

• classical pathway
• transporter proteins
• secretory vesicles (granules)
• exosomes
• microvesicles
• shaving, with sheddase

Question 2

How can the signals induce cell signalling in the target cells? (import of the signals into the cells)

Answer 2

• direct import of proteins
• receptor mediated signal transduction
• receptor- mediated signal transduction with other peptides
• vesicles fusion > fusion
• receptor- mediated interaction > vesicle fusion > cargo release

Question 3

What are the steps of neurotransmitter release?

Answer 3

1. synaptic vesicles stored with neutrotransmitters in synapses
2. depolarisation
   3.calcium gets in through channels
3. calcium interacts with synapsin
4. synapsin dissociates from vesicles
5. snare proteins are activated(syntaxin and SNAP-25)
6. SNARE complex forms with synaptobrevin
7. membrane of vesicle fuse with the cell membrane
8. NSF and SNAP disassemble SNARE complex
9. vesicles can be recycled again.

Question 4

What does Sarin do to the neurons?

Answer 4

Sarin fits on the enzyme acetylcholinesterase. By inhibiting this enzyme, acetylcholine will not be broken down and aggregate in the synapses. This will cause the muscle unable to relax.
Symptoms: shivering, foaming, fainting, inability to breath out.

Question 5

How are RNA molecules secreted?

Answer 5

• microvesicles
• exosomes
• lipoproteins
• argonaite
  last two are carrier proteins

Question 6

What types of extracellular RNAs are there?

Answer 6

• messenger RNA
• transfer RNA
• microRNA (degrades the mRNA inside the cell also)
• small- interfering RNA
• long non-coding RNA

Question 7

How can metastatic cancer break to barrier? ( e.g. the epithelial barrier)

Answer 7

• they can secrete miRNA that interfere with ZO-1mRNA. This means that the epithelial barrier will be compromised an that the cancer can further metastasis.

Question 8

What types of gasotransmitters are known currently?

Answer 8

• Nitric oxide (NO)
• Carbon monoxide (CO)
• Hydrogen Sulphide (H2S)

Question 9

What is the half life of each gasotransmitter?

Answer 9

• NO = seconds
• CO- minutes
• H2S = seconds- minutes

Question 10

What is the main function of NO as gasotransmitter?

Answer 10

NO can cause vasodilation through binding to guanylyl cyclase. THen GTP > cGMP which results in relaxation in the smooth muscle cell

Question 11

Give a list of all the functions of NO.

Answer 11

• LDL oxidation inhibition
• msooth muscle cell proliferation inhibition
• monocyte adhesion inhibition
• platelet aggregation inhibition
• superoxide radical elaboration inhibition

Question 12

From what is CO produced?

Answer 12

From heme in the spleen

Question 13

What is CO?

Answer 13

A gasotransmitter that can be vasodilatory, anti-thrombotic, anti-apoptotic and anti-inflammatory

Question 14

What pathways can CO activate?

Answer 14

• sGC
• MAPK (p38)
• Akt
• NO-release, calcium dependant

Question 15

CO and NO have a similar target molecule, what is it?

Answer 15

guanylate cyclase

Question 16

What is the precursor of H2S?

Answer 16

methionine that becomes homocysteine > cysteine > H2S

Question 17

Why is specifically cysteine needed for H2S.

Answer 17

Cysteine is the only amino acid that contains sulphur.

Question 18

What is the function of H2S?

Answer 18

• angiogenesis
• vasodilation
• lower mitochondrial respiration
• anti-inflammation
• anti-oxidation

Question 19

What are the classes of lipid derivatives?

Answer 19

• eicosanoids
• phosphoinositides
• sphingolipids
• fatty acids
• cholesterol derived molecules (hormones)

Question 20

What are the functions of lipid-derivatives?

Answer 20

• activators of G-protein coupled receptors
• activators of nuclear receptors

Question 21

What are the 4 main classes of hormones?

Answer 21

• amino hormones
• peptides
• eicosanoids (inflammation , blood pressure etc. )
• steroids ( sex hormones, blood sugar, immune suppression etc. )