Mid 1: Lec 6-7

Question 1

Vasculogenesis: when, from what, into what

Answer 1

Formation of blood vessels during early development, from angioblasts. Assemble into vascular labrynth

Question 2

5 VEGF proteins

Answer 2

VEGF A-D, placenta growth factor (PGF)

Question 3

VEGF major actions

Answer 3

stimulation of migration of endothelial
cells, mitosis of endothelial cells, matrix metalloproteinase
activity, creation of blood vessel lumen, creates new junctions
(fenestrations), inflammation and vasodilation.

Question 4

VEGF main receptors (inc: protein type)

Answer 4

-Receptor tyrosine kinases:
VEGFR 1-3

VEGFR 2 is the main in vascular endothelial cells

Question 5

VEGF co-receptors

Answer 5

Neuropilin (NRP): NRP1 and NRP2

Heparan sulfate proteoglycans (HSPGs)

Question 6

VEGF auxiliary proteins: What are they and examples

Answer 6

Don’t bind VEGF, but are present in the multiprotein complexes formed from VEGF binding its receptors and coreceptors

integrins, ephrin B2

Question 7

Angiogenesis

Answer 7

formation of blood vessels after early development. Sprouting occurs from existing blood vessels

Question 8

Arteriogenesis

Answer 8

Angiogenesis leads to arteriogenesis.

Endothelial cell channels are covered by pericytes or vascular smooth muscle cells (VSMCs)

Question 9

Intussusception

Answer 9

Pre existing vessels split to form a forked vessel

Question 10

Vessel cooption

Answer 10

tumorigenesis: tumor cells hijack exiting vasculature

Question 11

vascular mimicry

Answer 11

tumor cells create their own vessels out of themselves instead of using angiogenesis

Question 12

Angiogenesis sensors

Answer 12

Allow blood vessels to change to optimize blood flow

Oxygen sensors:
prolyl hydroxylase domain 2 (PHD2)

Hypoxia inducible factors:
Hypoxia inducible factor 2 alpha (HIF-2 alpha)

Question 13

Steps of vessel branching

Answer 13

Quiescence: Non sprouting state, default

Activation: Angiogenesis process begins

Resolution: Angiogenesis ends

Question 14

Angiogenesis steps (inc: what cell types are producing the signal)

Answer 14

Quiescent vessel senses angiogenic signal from hypoxic, inflammatory or tumor cell

matrix metalloproteinases mediate detachment of pericytes from vessel wall and release from basement membrane

VEGF increases permeability of endothelial cell layer, causing plasma proteins to extravasate and lay down an extracellular matric scaffold

Integren signalling causes endothelial cells to migrate to the scaffold

ECM is remodelled into an angio competent milieu

Tip cell leads the tip towards the target

Question 15

Tip cells (main activators and other activators)

Answer 15

One endothelial cell in the activated blood vessel that leads the other cells towards the target

main activator: VEGF
other activators: neuropilins and NOTCH ligands

Question 16

3 ways of blocking angiogenesis with drugs

Answer 16

interfere with ligand binding to receptor

inhibit ptk kinase activity (tyrosin receptor kinases are a type of protein tyrosine kinase)

block secondary messengers

Question 17

Bevacizumab (purpose and mechanism)

Answer 17

Treats cancer and mac degeneration by binding VEGF and preventing it from binding receptors

Question 18

Pazopanib (purpose and mechanism)

Answer 18

Treats renal cancer

selective RTK inhibitor that blocks tumor growth and inhibits angiogenesis

Question 19

Sorafenib (purpose and mechanism)

Answer 19

Treats cancers

RTK inhibtor, inhibits VEGFR cross-phosphorylation

Question 20

BIBF 1120

Answer 20

non-small cell lung carcinoma

VEGFR, FGFR, and PDGFR inhibitor,
blocks PTK kinase activity by binding to the ATP binding site

Question 21

Imaging VEGF and VEGFR complex (techniques and results): specific secondary structure of protein, how did they determine molecular weight, type of interaction between monomers

Answer 21

used electron microscopy

-used DNA constructs to express the extracellular domain (ECD) of VEGF2:
One of the constructs coded for an ECD monomer
One of the constructs coded for and ECD dimer with GCN4 coiled coil

ECD monomer and dimers were supplied with VEGF and the complexes were isolated using gel electrochromatography

Static light scattering to determine mol weight of the two types of receptor ligand complexes

electron microscopy used to look at conformations of complexes and unbound receptors

unliganded ECDs have low affinity for each other and have randomized conformations

Binding of VEGF to immunoglobin-like domains 2-3 of one receptor increases prob that vegf can bind to the other receptor

after the receptors are connected with vegf, immunoglobulin-like domain 7 are brought together which stabilizes the dimer (homotypic interactions)

Immunolike domain 4 facilitates cross over of the two monomers which stabilizes the dimer and maintains a more rigid conf (homotypic interactions)

Question 22

VEGFR Ig domains (function)

Answer 22

Immunoglobulin-like domains

stabilize the VEGFR dimer and maintain a specific conformation that is necessary for proper positioning of intracellular protein kinase domains