1 - Transdifferentiation

Question 1

What is the definition of transdifferentiation?

Answer 1

The conversion of one differentiated cell type to another (e.g. pancreatic to hepatocytes)

Question 2

What is TD often confused with and what is different about them?

Answer 2

• Confused with metaplasia
  -Which is the same as TD, but also included the conversion of stem cells - Is more of a pathological term used in biposy’s to say there’s presence of ectopic tissue

Question 3

Give me three reasons to study TD

Answer 3

1. Understanding cancer
2. To utilise it for reprogramming cells for regenerative medicine applications
3. To understand the normal developmental processes of the converting cell types

Question 4

Why is it important to study TD in the context of cancer?

Answer 4

It’s known to predispose to neoplasia (Cancer)

Question 5

What can understanding TD @ the molecular and cellular level gain us in the context of cancer?

Answer 5

1. Earlier diagnosis through identification of new biomarkers
2. Development of new therapeutics against newly identified markers

Question 6

What is Barretts Metaplasia and what often causes it?

Answer 6

TD from stratified squamous epithelium to intestinal columnar epithelium occurring in patches @ the oesophagus-stomach junction

Question 7

What are the statistics surrounding Barretts diagnosis?

Answer 7

1. 40-100 fold increased risk of oesophageal cancer
2. If becomes cancerous, 5-10% 5 year survival rate

Question 8

What are the symptoms of Barretts?

Answer 8

Pain and difficulties swallowing due to food being blocked by the cancer mass
Same for breathing if the condition has grown outwards into the wind pipe

Question 9

How is Barretts diganosed?

Answer 9

1. Endoscopy - see red patches @ junction and extending upwards
2. Biopsy - confirms evidence of TD and therefore Barretts

Question 10

Why is it important to study TD for the future of regenerative medicine/cell based therapies?

Answer 10

Can identify transcription factors or genes responsible for TD to allow in vitro reprogramming of SC’s into new cell types for development of cell-based therapies

Question 11

How would you harness the principles of TD in cell-based therapy applications?

Answer 11

1. Identify key TF’s/genes
2. Extract endogenous ASC’s from the patient
3. Treat cells with the key TF’s to transform the cells into your desired type
4. Transplantation of target cells back into patient to replace damaged tissue

Question 12

What are some future uses of cell-based therapies?

Answer 12

1. Transplantation to replace diseased tissue
2. Drug development in vitro
3. Study of disease progression in vitro

Question 12

Why is studying TD useful for understanding the normal developmental process of cell type development?

Answer 12

Studying TD is the easiest way to see the developmental process of how a cell fate is decided as occurs post-natal
This is something relatively unknown due to difficulties studying embryos

Question 13

What do we currently know about how cell fates are decided?

Answer 13

• It’s determined by the cells location in a morphogen gradient
• The level of morphogen it’s exposed to results in the activation or repression of certain genes
• This induces a cell fate onto the cell

Question 14

What is a morphogen?

Answer 14

An agent capable of inducing morphogenesis

Question 15

What is the Eguchi and Kodama criteria for TD having occurred?

Answer 15

1. See a loss of one phenotype and the gain of another
2. Proving that there’s a lineage relationship between ancestor and descendent (Cell B was once cell A)

Question 16

What are some methods of analysing the loss of one phenotype and gain of another in TD?

Answer 16

1. Morphology changes via microscope
2. Changes in gene expression via RNA-seq
3. Changes in protein expression via WB or immunostaining
4. Functional characterisation - checking the cells now behave like the new cell type

Question 17

What is the methodology behind analysing lineage relationship in TD?

Answer 17

1. Label the starting cell with a reporter gene (e.g. GFP)
2. Add the agents for TD to occur
3. Observe a phenotype change to confirm TD occurred
4. Observe if the reporter is still seen in the cells with a new morphology
5. If yes - descendent has come from the starting cell and thus lineage relationship has been proven

Question 18

What makes Barrett’s so important?

Answer 18

It’s the only known precursor to Oesophageal cancer