Adult stem cells in the gut

Question 1

How can stem cells be anchored in the stem cell niche?

Answer 1

Adhesions to the ECM or niche cells mediated by cadherin/integrin/other

Question 2

What is the difference between cadherin adhesions and integrin adhesions?

Answer 2

Integrins mediate adhesion between a cell and the ECM whereas cadherins mediate homotypic adhesion between cells

Question 3

How are adhesion molecules involved in stem cell regulation besides anchorage? (2)

Answer 3

• A gradual loss of cadherin adhesion as the stem cell departs from the niche can induce differentiation
• A gradual loss of cadherin adhesion during ageing leads to loss of stem cells in the niche

Question 4

What is the stem cell niche in the gut?

Answer 4

Crypts at the base of villi

Question 5

What are the stem cells in the gut?

Answer 5

Crypt base columnar (CBC) cells

Question 6

What is the marker for CBC stem cells?

Answer 6

Lgr5 (Wnt signalling)

Question 7

Where is Wnt signalling occurring in the intestines? (2)

Answer 7

• At the base of the crypts, decreases as you come up past the transit-amplifying cells
• Happening where it shouldn’t be in colorectal cancer

Question 8

How could stem cells be used instead of animal testing?

Answer 8

You can grow organoids from stem cells/reprogrammed adult cells which could be used to study drugs instead of animals

Question 9

What is an enterocyte?

Answer 9

A cell of the intestinal lining

Question 10

How do crypts form from a flat sheet of cells?

Answer 10

Ephrins are responsible for creating curvature

Question 11

What are the uses for organoids? (3)

Answer 11

• Experimental tool
• Diagnosis and disease modelling
• Therapeutics