L20 - EMT - epithelial cells in transition

Question 1

what are epithelial cells

Answer 1

polarised cells that form tight continous layers lining surfaces and cavities

= depends on cell0cell adhesions AND connections to basement membrane

Question 2

describe E-cadherin + β-catenin role inepithelial cell organisation

Answer 2

E-cadherin is a transmembrane adhesion protein taht binds to E-cadherin on adjacent cells

intracellularly E-cadherin binds to β-catenin -> binds to ⍺-catenin

= links complex to actin filaments
= ctructural and signalling roles

Question 3

what are Adheren junctionsand what are the main molecules involved in this

Answer 3

mechanically links cells together via actin cytoskeleton

E-Cadherins -> extraceular
β-catenin -> intraceular

Question 4

what are the structural and signalling roles of β-catenin

Answer 4

structural:
part of Adheren junction = helps link E-cadherins to actin cytoskeleton

signalling:
Wnt signalling pathway

Question 5

describe signalling pathway with β-Catenin WITHOUT Wnt

Answer 5

β-catenin continously degraded

= phosphoylated by destruction complex –> ubiquitinated + destroyed

Question 6

describe signalling pathway with β-catenin WITHOUT Wnt

Answer 6

Wnt binds to Frizzled LRP receptors

= inhibits ‘destruction complex’
= β-catenin stabilised and builds up in cytoplasm –> actiavtes transcription factors

Question 8

what ios EMT - epithelial-mesenchymal transition

Answer 8

epithelial ells lose cell0cell adhesions and polarity

= gain mesenchymal properties such as:
- motility
- invasiveness

Question 9

describe the hallamrks of EMT

Answer 9

E-cadherin = downregulated

β-catenin = move to nucleus for signalling

polarity = lost

migration = gained

Question 10

describe the regukation of EMT by transcription factors

Answer 10

repress E-cadherin expression

induce expression of mesenchgynal genes