Lecture 19 : Angiogenesis Role of VEGF and Hypoxia Flashcards

1
Q

What is Vasculogenesis?

A

Vasculogenesis is the embryonic formation of endothelial cells from the mesoderm layer precursors to form new blood vessels in blood islands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does Vasculogenesis give rise to?

A

Vasculogenesis give rise to the heart and the first primitive vascular plexus inside the embryo and in its surrounding membranes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Vasculogenesis is …?

A

Embryonic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens during Vasculogenesis?

A

During Vasculogenesis,

  1. Blood vessel formation first occurs in the wall of the yolk sac (Figure A)
    1. Undifferentiated mesenchyme cells condense to form Angiogenetic cell clusters (Figure B)
  2. These centers of Angiogenetic cell clusters (Figure B) form the blood cells form the primitive blood cells (Figure C)
    1. The outsides of the Angiogenetic Cell Clusters develop into blood vessel Endothelial Cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where do Vascular development in the embryo and extra-embryonic membranes occur?

A

The Vascular System form in two specific sites in the embryo:

  • One in the blood islands of the yolk sac
  • The other in the embryo proper
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Angiogenesis

A

Angiogenesis is the process by which new blood vessels from pre-existing vessels that are formed in the early stages of vasculogenesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the two stages of Angiogenesis?

A
  • Sprouting Angiogenesis
  • Intussusceptive Angiogenesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Sprouting Angiogenesis?

A

Sprouting Angiogenesis is when tissues that have low nutrient and oxygen supply will produce signals (VEGF-A) that induces endothelial cells to secrete proteases that degrade their basement membranes and allow the endothelial cells to escape their original vessel walls.

These cells continue to proliferate and form sprouts connecting neighboring vessels, guided by extending towards the source of the angiogenic signal.

  1. Basically… Low Oxygen and Nutrients produces VEGF-A signals
  2. VEGF-A signals induce endothelial cells to secrete proteases to disintegrate (degrade) their basement membranes and run away.
    1. This is done so the endothelial cells can escape from their original vessel walls.
  3. These same runaway endothelial cells will keep making copes if themselves and make sprouts that connect to neighboring vessels.
    1. They’re running towards the source of the angiogenic signal.
      1. The sprouts that these runaway endothelial cells are making that connect them to their neighbor vessels are all done while they’re following the origin of that angiogenic signal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Intussusceptive Angiogenesis?

A

Intussusceptive Angiogenesis is also known as splitting angiogenesis, which is the formation of new vessels by splitting a pre-existing vessel in two.

Basically…

  • Making a new blood vessel by splitting an existing blood vessel into two.
    • Turning one existing blood vessel into two blood vessels ~~~~~
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is Happening in the Diagram?

A

Angiogenesis is happening,

Angiogenesis is the formation of new blood vessels from existing blood vessels,

Can be either:

  • Sprouting Angiogenesis
    • or
  • Inusscepetive Angiogenesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are examples of Angiogenesis in Adults?

A

Angiogenesis in the uterine lining,

  • In Women, Angiogenesis happens each month for a few days in the lining of their uterus.
    • This happens during their Menstrual Cycle
    • New blood vessels are formed from their existing ones (Angiogenesis)

Angiogenesis in tissue during wound healing,

  • Angiogenesis happens in our tissue when we get hurt,
    • New blood vessels are made from existing ones (Angiogenesis) to heal our tissue when we get hurt.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain this Slide

A

Not sure if this slide is super important

  • The largest blood vessels are Arteries and Veins
  • Arteries have Veins have a thick layer of connective tissue and many smooth muscle cells
  • Arteries and Veins will have varying thicknesses depending on the diameter and function of those vessels.
  • Blood vessel interiors are only made from a single layer of endothelial cells.
    • ​This single layer of endothelial cells is attached to and separated from the other layers of the basal lamina.
  • The finest branches of the vascular system are the capillaries and sinusoids.
    • These are composed of endothelial cells and a basal lamina put together with a few perictytes.
    • Members of the connective-tissue family
    • related to vascular smooth muscle cells
    • Pericytes wrap themselves around the small vessels that have other important functions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the different Characteristics of Arteries, Veins, and Capillaries?

A

….Capillaries are the smallest of these blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe Capilaries

A

Capillaries are:

  • very thing
  • composed of a single layer of endothelial cells
  • can be:
    • continuous
    • Fenestrated
    • Sinusoid
      • Have incomplete basement membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What’s the hardest part of the binding process of Oxygen to Tissue?

A

Binding the first oxygen is the hardest step, one the first one binds, the others will bind more easily.

Check this again, slide 15

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is pO2?

A

pO2 is a measure of how much O2 is dissolved in the blood.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is right shift?

A

If you become acidotic

18
Q

How many molecules of Oxygen can Hemoglobin found in RBCs bind to?

A

4 molecules of Oxygen

19
Q

Go over what he said for slide 16

A

….

20
Q

What are the signalling mechanisms driving Vasculogenesis and Angiogenesis?

A

Fibroblast Growth Factor 2

VEGf, by one of it’s two receptors

As you form the initial tube,…., you’ll have a new system involving Ang1 signalling through Tie1 and 2?

Slide 17

21
Q

Neutralizing antibodies against VEGF block results in?

A

Embryonic development

Bone morphogenesis

Female reproductive cycling

Corneal angiogenesis

Growth of several tumor types in animal models

22
Q

What is the most critical factor for embryonic angiogenesis?

A

VEGF

23
Q

Blocking VEGF =?

A

Lethal

even 50% reduction of VEGF is lethal

24
Q

What is the main VEGF?

A

VEGF A

25
Q

???? Explaining Slide 20

A

What’s happening?

26
Q

?? What happens during Sprouting Angiogenesis?

A

When endothelial cell gets the right signal (VEGF A), its gets pseudopdial process and go into surrounding tissue

learns to new sprout, new cappilary forming

signal for this is high or low oxygen in surrounding tissue

High Oxygen = Hypoxia Induced Factor

degraded

Low Oxygen = HIF levels build up

stimulates transcription and build up of VEGF A, signal for Angiogenesis to take place

27
Q

?????What is HIF-1 regulated?

A
28
Q

???? Hypoxia pathway slide 24

A

oxygenaes it, ….., degrade

under hypox conditions, no … take places, … Hif 1B, targets various genes for ….

29
Q

??? Slide 25

A

?????

30
Q

??????? Slide 26 How is VEGF-A regulated?

A

……..

Under normal conditions,,

31
Q

?????? Slide 27

A

HIF1a is regulated at….

complex process involving .. HIF1A domain

end and C domain??

transactivating domains turn on different sets of genes

binding of HIF1a factor leads to… factor?

adequate supply, …. also HIF argenile hyd…

p300 doesn’t bind to gene?

32
Q

????? Slide 28?

A

Depending upon level of oxygen…

regulation of this gene will be tightly controlled

33
Q

What does Ang-1 do?

A

Ang-1 promotes vessel maturation by stimulating migration, adhesion, and survival of endothelial cells

34
Q

What does Ang-2 do?

A

Ang-2 disrupts connections between the endothelium and perivascular cells

35
Q

What does Ang-2 do in combination with VEGF?

A

In combination with VEGF, Ang-2 promotes neo-vascularization

36
Q

Ang-2 is an antagonist of ____ and does ____

A

Importantly, Ang-2 is an antagonist of Ang-1 and blocks its ability to bind to the Tie-2 receptor.

37
Q

How can Ang-2 have different effects?

A

Ang-2 has different effects depending upon whether VEGF is present or not

38
Q

What receptors function in Angiogenesis?

A

Angiopoietins 1/2 and TIE receptors

39
Q

???? What is going on in Slide 30?

A

…….

Need to have both VEGF and ANG 2 to???

40
Q

??? Slide 30

Explain how Angiopoietin/Tie-2 Receptor Signalling takes place

A

… lead to cell survival

produced by periocyte?

can also signal through by signaling ???

Just to give reference??

Not important to know all the details here,

main point is Ang1 qupoisent state

and 2 antigonizes, …. in presence of VEGf

41
Q

???? Slide 33

A

..Angiopoetin 1 is maintaining..

in regions where you need new capillaries, Angio1 drops off and 2 comes up,

result is formation of sprouts and branching structures and everything

will grow into region that’s hypxic, knows its hypoxic bc of high conc of VEGF… something..

Targeted growth of blood vessels in regions where it’s needed

if you get it where it’s not needed, you have other problems

42
Q

????????What is PDGF?

A

necesaary for the proliferation of pericytes and smooth muscle cells.

released and associated wit ECM,…

signals to periocytes to migrate and proliferate,,..

have …

can maintain them in their mature form