Vertebrate limb development: AP axis and coordination of the AP and PD axes

True or false: The dev of the AP and PD axes are coordinated

true

When there are low levels of FGF is a positive or negative feedback loop established?

positive

When there are high levels of FGF is a positive or negative feedback loop established?

negative

What axis does Shh specify?

AP

What axis does FGF specify?

PD

When there is low FGF is Shh stimulated or inhibted?

stimulated

When Shh activates Grem1 what does that stimulate low or high FGF?

low

Where is Shh located?

ZPA

Where is FGF located?

AER

True or false: This is the positive feedback loop between the AP and PD axes

Low FGF—>Shh—>Grem1—IBMP—IFGF

true

Does high levels of FGF activate or inhibit BMP?

activate

True or false: When there are high levels of FGF Grem1 is activated.

false

When there are low levels of FGF is a positive or negative feedback loop established?

postive

When there are high levels of FGF is a positive or negative feedback loop established?

negative

When there are high levels of FGF is BMP activated or inhibited?

activated

High levels of FGF leads to the inhibition or activation of gremlin?

inhibition

True or false: BMP inhibition of FGFs leads to loss of AER and ZPA

true

When BMP is activated what happens to limb development?

it ends

What does AER stand for?

Apical ectodermal ridge

What is the progress zone composed of?

mesenchyme and AER

True or false: Inhibition of gremlin activates BMP and inhibits FGFs.

true

What end is the growing tip of limbs located?

distal end

What end is RA located?

proximal

What end is FGF located?

distal

What does RA activates that leads to the development of the humerus in the arm/wing?

meis

At intermediate levels of FGF what hox gene is activated?

hox 11

What does hox 11 lead to the development of ?

the radisu and ulna

What hox gene does high levels of FGF activate?

hox 13

What does hox 13 lead to the development of?

carpals/digits

In an early stage limb bud when a later stage progress zone is grafted what happens?

graft produced distal structures immediately and are missing the ulna and radius

When a later stage progress zone is grafted why does it lead to the development of distal structures?

Because FGF levels are high

High levels of FGF leads to the development of what structures?

distal structures

Low levels of FGF leads to the development of what structures?

proximal structures

In a later stage limb bud when a early stage progress zone was drafted what happened?

graft produced duplicated proximal structures (radius and ulna)

When a early stage progress zone is grafted why does it lead to duplicated proximal structures?

because there are lower levels of FGF

When there are high levels of FGF that inhibits gremlin and activates BMP which leads to what?

end of limb growth

In the dev of PD axis where is FGF located?

distal end

In the development of the AP axis where is Shh located?

posterior

True or false: BMP shuts down AER, ZPA and Wnt7a along the DV axis?

true

When BMP shuts down AER, ZPA and Wnt7a along the DV axis what happens?

end of limb patterning

True or false: BMP, Wnt/B-catenin, and FGF all play a role in apoptosis.

true

BMP, Wnt/B-catenin, and FGF all activate what?

Dkk-1

What does the activation of Dkk-1 lead to?

apoptosis

True or false: Dkk-1 is a antagonist of Wnt

true

True or false: Pattern formation involves coordination of different axes and specification.

true

True or false: This is the pathway to apoptosis in C.elegans

EGL-1—ICED-9—ICED-4—>CED-3—>apoptosis

true

True or false: This is the pathway leading to apoptosis in mammals.

BAD—IBcl2—IApaf-1—>Caspases—>apoptosis

true

What is BAD?

a Bcl2 associated death promoter

What are two ways to control the number of cells?

apoptosis or death of damaged cells

What an example of an intracellular signal for apoptosis?

damage

Whats an example of an extracellular signal for apoptosis?

tissue development factors

When an apoptotic stimulus reaches the mitochondria what happens to the cytochrome c in the intermembrane space?

its released

What is activated in the mitochondria outer membrane that leads to the release of cytochrome c?

bax or bak molecules

Does Bcl2 inhibit or activate bax/bak molecules?

inhibit

After cytochrome c leaves the mitochondria what does it do?

activates adaptor proteins

After the adaptor proteins with cytochrome c assemble together, what happens after procapase-9 molecules are recruited?

an apoptosome is formed

What does the activation of procaspase-9 within the apoptosome lead to?

caspase cascade which leads to apoptosis

True or false: Procaspase-9 is the initiator caspase

true

What does the initiator caspase activate?

executioner caspases

What doe executioner caspases do?

cleave cellular molecules

What does the hippo pathway control?

organ size

True or false: Hippo and warts are tumor supressors

true

In drosophila what activates Hpo?

Ft (fat)

What does Hpo activate?

Wts (wart)

What does yorkie (yki) stimulate?

cell division

Does wts activate or inhibit yki?

inhibit

What type of genes does yki help transcribe?

cyclins and caspase inhibitor DIAP1

What do cyclins lead to?

cell proliferation

What is the Hpo pathway in drosophila?

Ft—>Hpo—>Wts—IYki—>target genes

In mammals what do atypical cadherins stimulate?

MST ½ (serine/threonine kinases)

What do MST ½ (serine/threonine kinase) activate?

LATS1/2 (serine/threonine kinase)

Does LATS1/2 activate or inhibit YAP transcriptional coactivator

inhibit

What does the YAP transcriptional coactivator activate?

cyclins and caspase inhibitor IAP

What is the MST1/2 pathway in mammals?

atypical cadherin—>MST1/2—>LATS1/2—IYAP transcriptional coactivator—>cyclins and caspase inhibitor IAP

In mammals does BAD activation lead to apoptosis?

yes

What is the apoptosis pathway in mammals?

BAD—IBcl2—IApaf-1—>Caspase—>apoptosis

In mammals what inhibits caspases?

IAPs

What happens when there is a loss of Hpo?

overgrowth

What is the Hpo equivalent in mammals?

MST1/2

What is the fat equivalent in humans?

atypical cadherins

What happens with the loss of yorkie (YAP)

loss of some structures/tissues

True or false: Yorkie/YAP are tumor suppressors

false

What can you use the FLP/FRT system for?

determine gene function

What can you use to insert FRT sequences?

CRISPR

What system is the FLP-FRT similar to?

CRE-LOX

What recognizes the FRT sequences for recombination?

FLP

What is FLP?

a recombinase enzyme

Where is FLP from?

yeast

True or false: FRT surrounds the gene of interest so it can be excised like in the CRE-LOX system.

true

True or false: The use of the FLP-FRT system is to bypass any early requirement of the gene of interest that could affect animal viability.

true

What does a heterozygous mutation of gfp mean?

one chromosome is marked with gfp and the other one isnt

What ensures that the animal will not die if the GOI is required for animal survival in the FLP-FRP system?

the tissue specific promoter that expresses FLP

When is FLP expressed?

before mitosis

What does FLP recombinase induce at the FRT sites?

recombination

What does the recombination at the FRT sites promote?

exchange between 2 chromosome arms

True or false: With FLP-FRT after recombination you will have similar sister chromatids.

false

After mitosis with FRT-FLP what will the resulting daughter cells be?

one with 2 normal chromatids and 1 with 2 mutated chromatids

With FLP-FRT after cell division are you able to compare the daughter cells and see if the GOI affects cell/tissue size?

yes

True or false: Using the FLP-FRT system in the hippo screen involves recombination between chromosomes and exchanges between chromosome arms.

true

The anterior-posterior axis of the limb is determined by the…?

zone of polarizing activity (ZPA)