L4 Questions

Question 1

Mechanisms by which dietary restriction reduces cellular senescence involve factors associated with the IGF-1-induced pathway. Inhibition of senescence can occur by:

1. blocking caspases
2. reduction of telomerase activity
3. increasing sirtuin-1 (SIRT1) activity
4. inhibiting autophagy

Answer 1

C. increasing sirtuin-1 (SIRT1) activity SIRT1 - activates FOXO1 which inhibits pro-ageing genes and activates longevity genes

Question 2

The senescence bystander effect can lead to:

1. a young person hanging around an old person aging faster than normal
2. pro-inflammatory factors from a senescent cell triggering autocrine apoptosis
3. pro-inflammatory factors from a senescent cell triggering autocrine inflammation
4. pro-inflammatory factors from a senescent cell triggering paracrine inflammation

Answer 2

D. pro-inflammatory factors from a senescent cell triggering paracrine inflammation senescence affects nearby cells not the cell itself, therefore paracrine (C). A is nonsense, also apoptosis doesn’t affect bystander cells (B)

Question 3

One approach to slow ageing in a multicellular organism is to:

1. activate apoptosis of senescent cells
2. activate necrosis of senescent cells
3. activate anti-inflammatory pathways/molecules
4. activate pro-inflammatory cytokine signalling in macrophages

Answer 3

A or C activate apoptosis of senescent cells. Destruction of senescent cells will reduce paracrine signals that activate senescence in nearby cells. C because less inflammatory lowers inflammaging and chronic diseases. Necrosis causes inflammation to nearby cells which could exacerbate the effects of ageing in other cells… D does not work as more mature macrophages usually lead to faster senescence

Question 4

4. With respect to nutritionally regulated mechanisms influencing senescence, if PTEN levels were high, affected cells would:
5. senesce faster
6. senesce more slowly

Answer 4

B. senesce slower

The PTEN gene provides instructions for making an enzyme that is found in almost all tissues in the body. The enzyme acts as a tumor suppressor, which means that it helps regulate cell division by keeping cells from growing and dividing too rapidly or in an uncontrolled way.