L5 - autophagy

Question 1

what is autophagy?

Answer 1

cellular eating - engulf cell cytoplasm (by lysosomes?)

Question 2

what may trigger autophagy?

Answer 2

• cellular stress
• hypoxia
• starvation
• DNA damage
• neurodegeneration?

-UPR stimulates autophagic pathway

Question 3

defects in autophagy can cause what types of diseases?

Answer 3

• cancer
• diabetes
• arthritis
• pulmonary fibrosis
• (due to aggregates)

Question 4

what is PIP3 and what is it’s significance in autophagy?

Answer 4

• phosphoinositide (phospholipids in cell membranes)

- required for membrane fusion/formation in autophagy

Question 5

how is cholesterol homeostasis controlled?

Answer 5

• SREBP regulates genes important for cholesterol synthesis
  High cholesterol- SREBP retained in ER by SCAP(cholesterol sensor) (assocaited by Insig-chaperone)
  Low cholesterol- SCAP dissociates from insig. SREBP transits to golgi - cleaved which released TFs which acitvate cholesterol producing genes

Question 6

what happens in CNX -/-?

Answer 6

large myelinated fibres

Question 7

what happens in CRT -/-?

Answer 7

cardiac issues

Question 8

give examples of ER folding diseases

Answer 8

• emphysema
• cystic fibrosis
• hypothyroidism

Question 9

give steps in macroautophagy

Answer 9

1) auophagic signals recieved
2) PAS (pre-autophagic structure fuses with plasma membrane)
3) structure then fuses with ER membrane to form phagophore
4) phagophore seals to form an autophagosome (double membrane)
5) autophagosome fuses with lysosome to form an AUTOLYSOSOME
6) autolysosome degrades products
7) if cell is starved broken down products used for cell survival