Biology Reference
In-Depth Information
CHAPTER TWO
What Goes Up Must Come Down:
Transcription Factors Have Their
Say in Making Ecdysone Pulses
Qiuxiang Ou, Kirst King-Jones
1
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
1
Corresponding author: e-mail address: kirst.king-jones@ualberta.ca
Contents
1.
Introduction
36
2. Historical Perspective
37
3. The Ecdysone Hierarchy I: Hormone Action at the Onset of Metamorphosis
39
4. The Ecdysone Hierarchy II: Early Response Genes
41
5. The Ecdysone Hierarchy III: Early-Late Response Genes and
b
ftz-f1
43
6. Upstream of the Hormone: Ecdysone Synthesis in the Prothoracic Glands
44
7. Role Reversal: The Ecdysone Hierarchy Regulates Its Own Hormone
49
8. broad Controls a Key Component of Cellular Cholesterol Transport
52
9. DHR4 is a Key Mediator of PTTH Signaling
54
10. DHR3/E75-Mediated NO Signaling Is a Critical Player of Ecdysteroidogenesis
56
11. Other Transcription Factors with Known Expression in the Prothoracic Gland
59
11.1 WOC (without children)
59
11.2 MLD (molting defective)
59
11.3 DRE4 (dre4)
60
11.4 Smad2/Med (smox/medea)
60
11.5 Per/Tim (period/timeless)
61
11.6 HLH54F (HLH54F)
62
11.7 Ttk (tramtrack)
62
11.8 CRC/ATF4 (cryptocephal)
63
References
63
Abstract
Insect metamorphosis is one of the most fascinating biological processes in the animal
kingdom. The dramatic transition from an immature juvenile to a reproductive adult is
under the control of the steroid hormone ecdysone, also known as the insect molting
hormone. During Drosophila development, periodic pulses of ecdysone are released
from the prothoracic glands, upon which the hormone is rapidly converted in periph-
eral tissues to its biologically active form, 20-hydroxyecdysone. Each hormone pulse has
a unique profile and causes different developmental events, but we only have a
