Lecture 9, cell signalling stem cells

Question 1

Name some major cell signaling pathways

Answer 1

There are 7 major cell signalling pathways in regards to stem cells: JAK/STAT, Hedgehog, SMAD signalling TGF beta, MAPK/ERK, WNT, NFkB, NOTCH

Question 2

What are the major component in NOTCH

Answer 2

Delta type ligand, notch receptor and gamma secretease. There are 4 types of Notch receptors and different types of ligands in mammals.

Question 3

What are the major component in JK/STAT

Answer 3

2 JAK/cytokine/EGF growth factor receptors and 2 STAT

Question 4

What are the major component in SMAD

Answer 4

TGF-B receptor type 1 and type 2 and SMAD

Question 5

Describe in basic terms the propagation of the signal from receptor to effector for Notch

Answer 5

There are two cells, one sending cell with more DLL then notch and one receiving cell with more notch then DLL. When DLL has become activated it binds to the extracellular Notch receptor. The extracellular Notch receptor is cleaved off the reciving cell and secretase gamma within the reciever cell cleaves the notch intracellular domain and the NICD is then free within the cytosol and can bind to a protein complex that can translocate to within the nucleus and then cause transcription of the Notch target genes.

Question 6

Describe in basic terms the propagation of the signal from receptor to effector for JK/STAT

Answer 6

2 cytokine receptors are found seperated in the cell membrane and when binding to cytokine the receptors binds to each other which brings the two JKs close together which leads to them phosphorylation each other. When the JK are phosphorylation they phosphate the cytokine receptors. This mediates the docking of w STAT proteins and they then becomes phosphorylation. The phosphorylation STAT then disccaoties form the receptors and then dimerezation of the STAT proteins. The STAT binds to the DNA and intiates transcription.

Question 7

Describe in basic terms the propagation of the signal from receptor to effector for SMAD

Answer 7

TGF-B signalling molecules binds to type 2 receptors which cause dimerization of the receptors. Dimerization recruits the type 1 receptors and they phosphorylate type 1 receptors and smad 2 or smad 3 The phosprorylated smad 2/3 disccatoies from the receptor and olgigomerize with smad 4. The smad 2/3-4 oligmer migrate to the nucleus and recruits other proteins that activate tranxcriåtion of specific target genes.

Question 8

Describe in basic terms the propagation of the signal from receptor to effector for MAPK/ERK

Answer 8

The EGF proteins in the mebrane act as cell receptors with two monomers. Outside the cell there is one EGF that binds to the EGFR which causes phorpsorylation of EGFR. A protein complex will bind to the psosphorylated receptor and catalyze intracellular events.

Question 9

What are the major component in MAPK/ERK signalling

Answer 9

The signalling molecule is EGF and the regulatory protein is ERK(MAPK) and EGFR protein that act as cell receptors.

Question 10

What are the major component in HEDGEHOG signalling

Answer 10

Answer this

Question 11

Describe in basic terms the propagation of the signal from receptor to effector for hedgehog signalling

Answer 11

Answer this