METABOLIC DISEASE AND STEM CELLS

Question 1

Why are stem cells important?

Answer 1

Cells can be regenerated from tissues that are dying and may be promising future therapies for diseases

Question 2

Arcuate nucleus - where is it, what type of neurons does it contain?
What is the impact of Leptin on both these types of neurons?

Answer 2

Arcuate nucleus - found in the Hypothalamus
Leptin stimulates both POMC and NPY neurons
Leptin –> Pomc. Leptin STIMULATES Pomc neurons which causes a coordination of events in the brain that lead to increased energy expenditure and decreased food intake
Lepin –l NpY. Leptin INHIBITS NpY neurons, which causes coordination of events in the brain that lead to reduced energy expenditure and increased food intake

Question 3

Where to Arcuate nuclei develop from?

Answer 3

HYPOTHALAMIC STEM CELLS

Question 4

Features of Hypothalamic stem cells

Answer 4

H.S.Cs are like RADIAL GLIA in appearance – can self renew OR differentiate into Arcuate Nuclei neurons

Question 5

What is the relevance of the portal capillaries?

Answer 5

No blood brain barrier here - allow communication between the brain and the body!!!!

Question 6

Demand for glucose throughout development – how is this relevant to Arcuate Nuclei?

Answer 6

Demand for glucose changes throughout life – NpY and Pomc neurons are generated from Hyothalamic stem cells which are found near the 3rd ventricle in response to glucose levels to adapt to the needs of the body

Question 7

Why is lineage tracing useful??

How can we investigate cell lineage further?

Answer 7

Can identify the key genes that maintain cell lineages. Can then go on to see

1) do cells still differentiate to this fate if these particular genes are knocked out?
2) do cells differentiate more or does this cause differentiation when genes are ectopically expressed?

Question 8

What is the function of the Islet1 gene ?

Mechanism of action?

Answer 8

Islet1 gene specifies the HYPOTHALAMIC MELANOCORTIN neurons.
—— Islet1 trans factor binds to Islet1 promoter causing transcription of the Pomc gene ——-

Question 9

NASIF ET AL - mice study on Islet1 - what did they do?

Answer 9

• Mutated Islet1 promoter
• Inactivated the Islet1 gene —> caused impaired Pomc expression
• No appetite supression!!

Question 10

LINEAGE TRACING - what is the method?

— a variation of the ‘conditional’ effect —

Answer 10

FLOX GENE OF INTEREST
Clone a cell-specific promoter
Clone cre enzyme downstream and fuse with ERT2 (flourescent reporter gene)
Cross mice and the cre cuts out the gene and activates Flourescence in reporter, but ONLY UPON INJECTION OF TAMOXIFEN

Question 11

Is lineage tracing possible in stem cells?

Answer 11

Clone Cre-ERT2 downstream of stem cell specific promoter
Produce a 2nd transgenic line where the reporter gene is separated from the regular promoter by a FLOXED STOP SEQUENCE
Breed mice – Tamoxifen will RECOMINE OUT the stop sequence and activate expression of the flourescent reporter

Question 12

GLAST:CreERT2 mice - what do they report?

Answer 12

Reports the presence of a-tanocytes - - can do this by the production of a transgenic mouse line

Question 13

What are A-Tanocytes?

Answer 13

Cells which can self-renew and also give rise to NpY neurons.
Hypothalamic stem cell-like cells.

Question 14

What are Melanocortins?

Answer 14

Satiety-induced Neuropeptides
Specified by Islet1 - (Islet1 trans factor binds to Islet1 promoter and caused transcription of Pomc gene, which causes suppression of appetite)