Heart development

Question 1

Where do cardiac cells originate from?

Answer 1

Ventral lateral mesoderm- splanchnopleura

Question 2

Where do heart precursors come from?

Answer 2

1. First heart field (in cardiac crescent)

2. Second heart field (medial and posterior to the crescent)

Question 3

What is tinman and what is its vertebrate homolog?

Answer 3

Tinman:
homebox gene
expressed in mesodermal precursors 
essential for the differentiation, proliferation and specification of cardiac progenitor cells
Vertebrate homolog= Nkx2.5

Question 4

What induces Nkx2.5 expression?

Answer 4

BMP2

Question 5

What are the 2 layers of the heart tube?

Answer 5

1. Endocardium- precursors of the endothelial lining of heart & valves
2. Myocardium- precursors of the myocytes of the atria and ventricles & purkinje fibres

Question 6

What is dmef2 essential for?

Answer 6

Cardiac muscle differentiation

Question 7

What is the vertebrate homolog of dmef?

Answer 7

Mef2 family

specifically Mef2C

Question 8

What is GATA?

Answer 8

Transcription factors (zinc finger proteins) essential for cardiogenesis
GATA 4-6= Cardiogenesis
GATA 4 KO mice= fail to form a heart tube

Question 9

What happens in looping of the heart?

Answer 9

The heart loops to the right

Lefty & Shh expressed in the left side of the embryo

Question 10

What is essential for asymmetric heart looping?

Answer 10

Signalling through activin inhibits Shh expression on the right hand side of the embryo
INV and IV genes

Question 11

What do mutations in IV cause?

Answer 11

Random reversal of heart looping

Question 12

What do mutations in INV cause?

Answer 12

Complete reversal of heart looping

Question 13

What is INV and IV required for?

Answer 13

Cilia rotation- establishes a preferential flow of Nodal and Lefty molecules to the left hand side

Question 14

What genes are required for chamber formation?

Answer 14

dHand- right ventricle

eHand- left ventricle