W2: Molecular Regulation of Development

Question 1

___ gradient dictates differentiation of dorsal-ventral differentiation.

Answer 1

BMP - bone morphogenetic protein

Dorsal - minimum
Ventral - max

Question 2

What regulates differentiation of mesodermal cells?

Answer 2

BMP

Question 3

There is high/low BMP signaling at the lateral plate.

Answer 3

High (max at ventral)

Question 4

There is intermediate BMP signaling at the ___.

Answer 4

somite

Question 5

There is high/low BMP signaling at the notochord.

Answer 5

low

Question 6

___ protein is inhibitor of BMP, a BMP antagonist.

Answer 6

Chordin

Question 7

Chordin is an extracellular protein that binds ___, preventing it from binding to its receptor.

Answer 7

BMP

Question 8

At the dorsal/ventral end, the BMP cannot be signaled.

Answer 8

Dorsal (minimal BMP due to Chordin)

Question 9

Formation of dorsal/ventral tissues dictated by Spemann organizer

Answer 9

dorsal

Question 10

DV cell differentiation:

AP patterning:

Answer 10

BMP, Chordin/Noggin

Hox gene

Question 11

D - __ control

V - __ control

Answer 11

D - Chordin/Noggin control

V - BMP control

Question 12

There is spatial and temporal collinearity in ___ gene expression.

Answer 12

hox

Question 13

What is a signaling molecule that induce cell fates during embryo development (examples) and where does it come from?

Answer 13

Morphogen (Chordin)

come from organizing center

Question 14

What is TGFβ?

Answer 14

Transforming growth factor beta

Largest family of growth factors (ex. BMP)

Question 15

What is BMP?

Answer 15

Bone Morphogenic Proteins

A growth factor that induces cell differentiation at DV axis

Question 16

What is a Hox gene and why is it significant?

Answer 16

Aka. homeobox gene

Gene that codes for DNA binding protein that provide regional identity at the AP axis

Question 17

What is BMP4? Where is it secreted from and what does it do?

Answer 17

Growth factor that induces the ventral tissue;

secreted from ventral mesoderm

Question 18

What is Chordin? Where is it secreted from and what does it do?

Answer 18

Secreted protein that induces neural tissue in dorsal ectoderm;

secreted from the dorsal (Spemann) organizing tissue (inhibit BMP)

Question 19

Where does BMP act in the embryo? Chordin?

Answer 19

BMP acts on ventral side
(BV)

Chordin acts on dorsal side (inhibiting BMP)
(CD)

Question 20

What is Rhombomere 3 and its significance in RA exposure of embryo?

Answer 20

Anterior-most border of Hox gene expression that corresponds to hindbrain segment. RA exposure can have detrimental impact on brain development by ectopic expression.

Question 21

What happens when embryo is treated with RA?

Answer 21

Anterior boundaries of Hox gene expression move more anteriorly, expressing ectopically in the anterior region (around the head)

Question 22

What is RA? What effect does it have on the embryo and what is the mechanism behind it?

Answer 22

RA is a ligand that binds to an NR called RAR, ultimately turning on transcription that leads to ectopic activation of Hox genes during the embryo’s development (in the head and CNS).

Question 23

Regulators at
D-V axis:
A-P axis:

Answer 23

D-V axis: BMP/Chordin

A-P axis: Hox gene

Question 24

retinoic acid (RA or accutane) is associated with AP/DV axis.

Answer 24

AP (hox gene)

Question 25

RA dosage changes have similar impact by defect in mesoderm differentiation/hox gene

Answer 25

hox gene