17. Sex determination

Question 1

What is the role of SRY?

Answer 1

Expression initiates male development and determination

Same process of development for males & females until SRY is expressed

Question 2

What does SRY expression cause?

Answer 2

SOX9 expression –> Sertoli cell differentiation –> formation of testes

Question 3

What are they key regions of SRY?

Answer 3

1. High mobility group domain - most XY females have mutation here
2. Nuclear localisation signals - targets for phospohorylation & acetylation - can cause XY sec reversal

Question 4

What genes does SOX9 target?

Answer 4

AMH & PGDS

Question 5

How does SRY activate SOX9?

Answer 5

SRY binds to TESCO sequence of SOX9

SOX9 also binds to TESCO - positive feedback loop to maintain SOX9 expression

Question 6

What occurs in the absence of SRY expression?

Answer 6

WNT4 & FOXL2 expressed –> upregulate other genes –> oocyte production, ovarian follicle formuation