Control of Animal Development by Steroid Hormones

1. Control of Animal Development by Steroid Hormones Craig T. Woodard Mount Holyoke College

7. BACKGROUND • The life cycle of Drosophila melanogaster has a duration of ten to • twelve days, during which the embryodevelops intoa larvae • to a stationary pupa and finally ecloses into the adult fly. This • transition from larvae to adult is known as metamorphosis and • is controlled by the steroid hormone, ecdysone. The Life Cycle of Drosophila melanogaster

8. 20-hydroxyecdysone

9. Drosophila Life Cycle

10. Ecdysone Timeline in Drosophila melanogaster Prepupal-Pupal Transition Destruction of Larval Body Parts by Programmed Cell Death Formation of Adult Body Parts by Morphogenesis Pupariation (Entry into Metamorphosis)

11. How can a single steroid hormone elicit different responses at different times in development?

12. Ecdysone Timeline in Drosophila melanogaster Prepupal-Pupal Transition Destruction of Larval Body Parts by Programmed Cell Death Formation of Adult Body Parts by Morphogenesis Pupariation (Entry into Metamorphosis)

13. How can a single steroid hormone elicit different responses in different parts of the body during development?

14. Ecdysone Timeline in Drosophila melanogaster Prepupal-Pupal Transition Destruction of Larval Body Parts by Programmed Cell Death Formation of Adult Body Parts by Morphogenesis Pupariation (Entry into Metamorphosis)

15. Morphogenesis of Adult Body Parts Pupariation (Entry into Metamorphosis) Destruction of Larval body Parts by Programmed Cell Death

16. Hypothesis A. ßFTZ-F1provides the early genes, the BR-C, E74A and E75A with the competence* to be reinduced by the prepupal ecdysone pulse. 1) These early genes then direct morphogenesis of adult body parts. B. ßFTZ-F1provides the prepupal stage-specific E93 early gene with the competence* to be induced by ecdysone. ßFTZ-F1thus directs the stage-specificity of the E93 response to ecdysone 1) E93 then directs programmed cell death in larval body parts. *Competence the ability to respond to an inductive signal

17. Morphogenesis of Adult Body Parts Pupariation (Entry into Metamorphosis) Destruction of Larval body Parts by Programmed Cell Death

18. Hypothesis A. ßFTZ-F1provides the early genes, the BR-C, E74A and E75A with the competence* to be reinduced by the prepupal ecdysone pulse. 1) These early genes then direct morphogenesis of adult body parts. B. ßFTZ-F1provides the prepupal stage-specific E93 early gene with the competence* to be induced by ecdysone. ßFTZ-F1thus directs the stage-specificity of the E93 response to ecdysone 1) E93 then directs programmed cell death in larval body parts. *Competence the ability to respond to an inductive signal

19. Morphogenesis of Adult Body Parts Pupariation (Entry into Metamorphosis) Destruction of Larval body Parts by Programmed Cell Death

20. ßFTZ-F1 protein binds to the E93, E74A, E75A, and BR-C genes. Ectopic (over) expression of ßFTZ-F1 in transgenic larvae provides E93 with the competence to respond (prematurely) to the late larval ecdysone pulse. Induction of BR-C, E74A and E75A transcripts by ecdysone is enhanced significantly by ectopic expression of ßFTZ-F1. A Loss-of-function mutation in ßFTZ-F1 results in dramatic reductions in E93, E74A, E75A, and BR-C activation at the end of the prepupal stage. A loss-of-function mutation in ßFTZ-F1 results in pupal lethality with defects in larval salivary gland programmed cell death, head eversion, and leg elongation. Evidence in Support of our Hypothesis

21. Levels of Early Gene Transcripts are Reduced in ßFTZ-F1 Mutant Prepupae

22. head eversion leg elongation wing extension ßFTZ-F1 Mutants Exhibit Pupal Lethality and Defects in Morphogenesis

23. Mutations in ßFTZ-F1 Disrupt Leg Morphogenesis Control ßFTZ-F1 Mutant

24. Third Instar Larva Leg Disc Eversion Adult

25. Cell Shape Changes During Leg Disc Elongation a b Courtesy of Condic et al. 1991. Development 111:23-33

28. Comparative Leg Development Control ßFTZ-F1 Mutant

30. Possible Causes of Short Legs 1) Contraction of the muscles is too weak in ßFTZ-F1 mutants. 2) There is something wrong with the leg imaginal discs in ßFTZ-F1 mutants, which prevents them from extending.

32. Leg and Wing Length in ßFTZ-F1 Mutants can be Rescued by a Drop in Pressure Significant Difference Significant Difference

33. Leg and Wing Length in ßFTZ-F1 Mutants can be Rescued by a Drop in Pressure

34. Possible Causes of Short Legs 1) Contraction of the muscles is too weak in ßFTZ-F1 mutants. --------------------------------------------------------------- 2) There is something wrong with the leg imaginal discs in ßFTZ-F1 mutants, which prevents them from extending. RULEDOUT

35. Possible Causes of Short Legs 1) Contraction of the muscles is too weak in ßFTZ-F1 mutants. This is supported by our careful observations of control and ßFTZ-F1 mutant animals going through the Prepupal-Pupal Transition. The ßFTZ-F1 mutants exhibit severe defects in muscle contractions.

36. Conclusions: Morphogenesis ßFTZ-F1 directs the muscle movements that generate internal pressure (at the appropriate time), which drives extention of legs and wings, and eversion of the heads. We are attempting to determine which ßFTZ-F1 target genes are involved in these processes.

37. Morphogenesis of Adult Body Parts Pupariation (Entry into Metamorphosis) Target Genes? Destruction of Larval body Parts by Programmed Cell Death

39. ßFTZ-F1 Mutants Fail to Activate E93 in the Larval Salivary glands control ßFTZ-F1 mutant E93 rp49 E93 rp49 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14

40. Normal salivary gland histolysis ßFTZ-F1 Mutants Fail to Destroy Larval Salivary Glands ßFTZ-F1 Mutant

41. ßFTZ-F1 Mutants are Defective in DNA Fragmentation Mutant

43. Ectopic Expression of ßFTZ-F1 Induces Premature Activation of E93 w w;P[F-F1]

44. Ectopic Expression of ßFTZ-F1 Induces Premature Cell Death

45. Ectopic Expression of ßFTZ-F1 Activates Cell Death Genes (an Apaf-1 homolog) (a Caspase) LOADING CONTROL

46. Induction of Cell Death by ßFTZ-F1 Requires E93

47. Activation of Cell Death Genes by ßFTZ-F1 Requires E93

48. Conclusions: Programmed Cell Death ßFTZ-F1 enables ecdysone to activate E93 in cells (such as those in the larval salivary gland) that are to be destroyed by programmed cell death. E93 then activates other genes that direct programmed cell death. Thus, the right cells are destroyed at the right time.

49. Morphogenesis of Adult Body Parts Pupariation (Entry into Metamorphosis) Target Genes? Cell Death Genes Destruction of Larval body Parts by Programmed Cell Death

50. Mount Holyoke College Leg Morphogenesis Tina M. Fortier** Priya Vasa Paejonette Jacobs E93 and Programmed Cell Death Tina M. Fortier** Samara Brown** Zareen Gauhar Michael Chapman Biology 340 Classes Mutagenesis of ßFTZ-F1 Jennifer R. McCabe Lynn L’Archeveque Margaret Lobo Emily McNutt ßFTZ-F1 Gene Structure Dana Cruz Tetyanya Obukhanych Petra Scamborova University of Utah Carl Thummel Julie Broadus Bart Endrizzi University of Maryland Eric Baehrecke Cheng Yu Lee Special Thanks for Technical Assistance George Cobb Rachel Fink Janice Gifford Tamara Hjermstad Diane Kelly This research was funded by the National Science Foundation Acknowledgments • Mechanism of ßFTZ-F1 Action • Diyya Mathur • Genome-Wide Functions of ßFTZ-F1 • Katie McMenimen • Vidya Anegundi • Rhiana Menen • Other • Cindy Chang • Jacque Miller