Differentiation 4 - cell fate decisions during development

Question 1

Name 8 different cell types in the pancreas

Answer 1

• acinar cells
• duct cells
• alpha cells -> glucagon
• beta cells -> insulin
• delta cells -> somatostatin
• PP cells -> pancreatic polypeptide
• epsilon cells -> ghrelin

Question 2

What is the order of cell differentiation in the pancreas?

Answer 2

• endoderm
• then goes to pancreatic buds
• these pancreatic buds then go to endocrine precursors or exocrine precursors
• endocrine precursors go to either PP cells or alpha cells
• PP cells go to either beta cells or delta cells
• exocrine precursors then go to exocrine cells or duct cells

Question 3

Where does the pancreas develop from?

Answer 3

• endoderm - dorsal end
• endoderm forms the pancreatic bud, liver, gall bladder and stomach

Question 4

What are endoderm cells expressing

Answer 4

Cdx2

Question 5

How do cells from the endoderm become pre-pancreatic?

Answer 5

switching on Pdx1 and Hlxb9

Question 6

How do cells become pre-pancreatic in the correct location?

Answer 6

• as gut cells proliferate it loops so one section becomes close to notochord
• notochord secretes fgf2
• cells in this region that receive the signal express Pdx1
• forming pre pancreatic region

Question 7

What are the lineage and environmental factors deciding pre-pancreatic fate?

Answer 7

lineage - Cdx2 expression gives gut cells potential to become pre-pancreatic

environment - Cdx2 activates Pdx1 only if fgf2 signal is received

Question 8

explain the differentiation of the common myeloid progenitor

Answer 8

• can differentiate into either erythriod or myeloid cells
• erythroid - need TF GATA1
• myeloid - need TF PU.1
• the myeloid progenitor expresses both GATA1 and PU.1
• they inhibit each other
• they auto regulate to boost activity
• one will win over other

Question 9

Describe the PU.1 repression of GATA1 activity

Answer 9

• GATA1 bound to target gene
• PU.1 binds to GATA1
• knocks off co-activator protein
• recruits chromatin methylation protein
• tightens chromatin making it less accessible

Question 10

What is the role of PAX6 in drosophila eye development?

Answer 10

• encodes paired box and homeodomain transcription factor
• expressed in early anterior ectoderm
• it regulates the very start of the eye formation process

Question 11

What cells does PAX6 regulate the transcription of in drosophila?

Answer 11

• photoreceptors
• pigment cells
• lend cells
• supporting cells
• glial cells

Question 12

is PAX 6 in humans?

Answer 12

Yes

Question 13

can a single TF determine the identity of a whole organ?

Answer 13

Yes