Mid 1: Lec 4-5

Question 1

Wnt _crine

Answer 1

autocrine and paracrine

Question 2

Wnt general function

Answer 2

controls segment polarity involved in formation of body axis, lateral symmetry during embryo development

Question 3

Wnt protein (protein chemical properties)

Answer 3

Ligand for Wnt path

lipid modifed glycoproteins that are palmitoylated and glycosylated

Question 4

Wnt canonical path sequence

Answer 4

Wnt binds frizzled, LRP binds frizzled, dishevelled is activated, B-catenin is freed from B-catenein destruction complex, moves to nucleus, groucho is displaced from TCF and transcription starts

Question 5

beta catenin destruction complex

Answer 5

axin holds everything together, GSK3 beta phosphs bcatenin which is then ubiqutiniated and proteolysed

Question 7

Azzolin et al general

Answer 7

YAP and TAZ are parts of b catenin destruction complex

Question 8

Immunoprecipitation

Answer 8

Antibody pulls desired protein and proteins that are attached to it out of solution. Western blot is used to identify all the proteins

Question 9

Azzolin destruction complex pulldown

Answer 9

Immunoprecipitation of axin1 in Wnt OFF condition

axin binds GSK3b, b-catenin, TrCP (all known parts) as well as YAP and TAZ during Wnt off

YAP/TAZ localizet to nucleus in absense of axin

Question 10

YAP related results of application of Wnt (molecules and timing, reporter, gene expression)

Answer 10

LRP6 releases YAP/TAZ from the destruction complex

YAP localizes to nucleus

Activation of TEAD reporter (TF)

Activation of YAP/TAZ target genes Cyr61 and Ankrd1

YAP/TAZ nuclear accum approx 30 minutes after application which is comparible to first detection of TCF/bcatenin teporter TOPFLASH

Question 11

Wnt in intestines (location and function)

Answer 11

all crypt cells, not in villi

in vitro regen of cryptlike structures

Question 12

Azzolin Y/T intestinal crypts

Answer 12

Nuclear localization in response to wnt

Y/t ectopically stabilized after knockout of APC (destructon complex protein)

Question 13

APC in intestine

Answer 13

Tumor suppressor, mutation leading to inactivation leads to cancer

part of destruction complex

Question 14

Treatment of APC induced intestine cancer

Answer 14

in azzolin deletion of YAP/TAZ caused mutant crypts to dissappear

Question 15

YAP/TAZ effect on Wnt signalling

Answer 15

Yap taz inhibits wnt signalling through b catenin

b-catenin levels increase in response to yap taz depletion

Question 16

yap taz and embryonic stem cells

Answer 16

b catenin transcriptional responses required for ES maintenence (w/o b catenin differentiation occurs)

YAP/TAZ knockout mimics GSK3 inhibitor drugs normally used for stem cell culturing

knocking out YAP/TAZ maintains stem cell phenotype w/o drugs

Question 17

YAP in absence of Wnt ligand

Answer 17

part of destruction complex and recruit beta TrCp (ubiquition ligase for b catenin). Part of negative regulation of wnt signaling

Question 18

Hippo signalling

Answer 18

Increased cell density leads to activation of hippo signalling which switches off yap/taz