Cell Signaling Pathways: Growth Factors

Question 1

What are growth factors?

Answer 1

things that are capable of inducing cell growth, proliferation, healing, and/or differentiation

Question 2

What are most growth factors?

Answer 2

proteins/peptides and steroids

Question 3

How does signaling for protein/peptide growth factors start?

Answer 3

binding to cell surface receptors

Question 4

Major families of growth factors receptors :

Answer 4

tyrosine kinase, serine/threonine kinase, and G protein coupled receptors

Question 5

What are the 2 receptors that nerve growth factor binds to?

Answer 5

TrkA and p75NTR

Question 6

TrkA signalling pathways

Answer 6

1. Ras–> Raf –> MEK–> ERK
2. PLC –> PI3 kinase
   -do not need to know specific pathways, just know that there are 3-4 main pathways that it is able to go through

Question 7

What is the main pathway from p75ntr

Answer 7

NF k B
-important for making bones

Question 8

What are the 2 main receptors that epidermal growth factors bind to?

Answer 8

EGFR and HER-2-3-4 heterodimer receptor

Question 9

What is pathway after epidermal growth factor binds to EGFR receptor?

Answer 9

-lead to activation of transcription factors that lead to cell survival and proliferation

Question 10

What is pathway after epidermal growth factor binds to HER 2-3-4 receptor?

Answer 10

endocytosis pathway that activate cell survival and cyclin D1 control (Cell cycle control)

Question 11

Genes for many growth factors or their receptors are…

Answer 11

proto-oncogenes

Question 12

What does it mean if something is the pro form of something else?

Answer 12

it is the longer version and needs be cleaved before it is activated
-done by proprotein convertase

Question 13

What is the best studied proprotein convertase?

Answer 13

furin

Question 14

Cleaving of proprotein will allow what kind of cell signaling?

Answer 14

paracine

Question 15

No cleavage of a proprotein will allow what kind of cell signaling?

Answer 15

juxtacrine

Question 16

What does ADAMT-4 do?

Answer 16

causes degradation of cartilage in the joints

Question 17

what cleaves the TGF-b superfamily proproteins ?

Answer 17

furin

Question 18

Synthesis of TGF-b

Answer 18

-formation of TGF-b precursor
-dimerization and cleavage by furin
-stay associated with part cleaved off (small latent complex)
-bind to LTBP to form large latent complex
-move to the extracellular

Question 19

What causes activation and release of TGF-b?

Answer 19

-acidic pH
-proteases
-thrombospodin-1
-integrin mediated activation
-ROS (reactive oxygen species)

Question 20

What receptor does TGF-b bind to?

Answer 20

type II receptor (serine/threonine kinase)
-type 1 is then recruited and phosphorylated
-type 1 then phosphorylates SMAD protein

Question 21

Conical pathway for TGF-b binding activates what?

Answer 21

SMAD pathway for regulated gene transcription

Question 22

what does the SMAD-dependent intracellular signaling cascade do?

Answer 22

activates or inhibits gene transcription

Question 23

What does myostatin do?

Answer 23

inhibit muscle growth

Question 24

4 phases of wound healing:

Answer 24

-hemostasis: platelets aggregate at injury site to form fibrin clot to control bleeding
-inflammatory phase: bacteria and debris removed
-proliferative phase: angiogenesis, collagen deposition, granulation tissue formation
-remodeling: collagen remodeled realigned along tension force lines and cells no longer needed removed by apoptosis

Question 25

What things can interfere with wound healing?

Answer 25

diseases, diabetes, venous/arterial disease, old age, and infection

Question 26

Canonical BMP signaling:

Answer 26

BMP binds to BMPR1 and 2
-causes phosphorylation of SMAD1 and 5
-SMAD 4 joins and then they regulate gene expression

Question 27

What is reciprocal induction?

Answer 27

signaling of tissues back and forth for the formation of very complex structures
-used to form the teeth

Question 28

Formation of salivary gland:

Answer 28

start looking like a mushroom
-growth factors of mesenchyme and epithelia work together to form the invaginations and very complex structure

Question 29

Is growth factor expression the same in every cell at all times?

Answer 29

no, changes based on time in development and type of cell being looked at

Question 30

Do growth factors work independently?

Answer 30

no, many work together at one time to ensure that everything is forming correctly

Question 31

If growth factor is turned on for too long, what can happen?

Answer 31

-there can be failure to move on to the next step in the sequence
-differentiate cells in the wrong place

Question 32

What does tumor necrosis factor activation lead to?

Answer 32

activation of caspase cascade and apoptosis

Question 33

Why are platelet-derived growth factors (PDGFs) important in dentistry?

Answer 33

being studied to see if they can be used as treatment for periodontal disease

Question 34

When you hear autoimmune, what is usually involved?

Answer 34

TNF

Question 35

Inflammatory bowl disease

Answer 35

-autoimmune
-TNF-alpha involved in chronic inflammation
-treatment is antibodies that block TNF-alpha from binding to receptor

Question 36

Rheumatoid arthritis

Answer 36

autoimmune
-treatment: use antibodies that bind to TNF receptor or add decoy receptor to take all TNF alpha away

Question 37

Beefy cow and kid have what?

Answer 37

deficiency in myostatin

Question 38

What BMP mutation does Grace have?

Answer 38

bachydactyly (short ass thumbs)

Question 39

what is dr. dallas’s favorite growth factor?

Answer 39

TGF-b

Question 40

how are growth factors restricted?

Answer 40

temporally and spatially