Susan Sadler
Associate Professor
Department of Biological Sciences
University of Denver
Denver, Colorado 80208
Office: (303) 871-3454
SG Mudd 278
Lab: (303) 871-3459
E-mail: ssadler@du.edu
Degrees:
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1977 B.A., Chemistry
The Colorado College - Colorado Springs, CO -
1982 Ph.D., Pharmacology
University of Colorado School of Medicine - Denver, CO
Research Interests:
Steroid hormones (progestins and androgens) and peptide hormones (insulin and insulin-like growth factor 1) stimulate meiotic division in amphibian oocytes - stimulating the development of oocyte to egg.
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| Amphibian oocytes are large and distinctly pigmented cells that can be microinjected under a stereomicroscope. Biochemical events can then be correlated with and compared to the meiotic maturation response that is indicated by white formation as the nucleus moves to the surface of the cell and pushes aside the melanin pigment before spindle formation and polar body extrusion. |
Over the years, my lab team has studied the early molecular events that trigger meiotic cell division. We have collected evidence showing that hormone-induced triggering mechanisms include:
- inhibition of adenylyl cyclase (the enzyme that synthesizes cAMP) independent of the G-alpha-i subunit of heterotrimeric G protein (by progesterone and IGF-1)
- stimulation of cGMP-inhibited phosphodiesterase type 3 (by insulin, IGF-1 and ras protein)
- migration of p21ras protein to the oocyte membrane (by insulin)
- receptor-mediated endocytosis of the insulin/IGF-1 receptor (by insulin and IGF-1)
- inhibition of farnesyl transferase activity (by insulin and IGF-1) [this is the enzyme that attaches lipid anchors to the p21ras protein]
Currently, the lab is evaluating how oocyte membrane fluidity and cholesterol-rich, low-density membrane domains might be affected by inducing hormones.
Recent Publications:
- Sadler SE, Archer MR, and KM Spellman (2008) Activation of the progesterone-signaling pathway by methyl-beta-cyclodextrin or steroid in Xenopus laevis oocytes involves release of 45-kDa G-alpha-s. Dev. Biol. 322:199-207. (DOI: 10.1016/j.ydbio.2008.07.031)
- Sadler SE (2007) The Physical Self-A Look at Biology for Women, ISBN 1-59399-247-5, Copley Custom Textbooks, XanEdu Custom Publishing, Ann Arbor, Michigan
- Sadler SE, and Jacobs ND (2004) Stimulation of Xenopus laevis oocyte maturation by methyl-beta-cyclodextrin. Biol. Reprod. 70:1685-1692. (DOI: 10.1095/biolreprod.103.026161)
- Sadler SE (2001) Low-density caveolae-like membrane from Xenopus laevis oocytes is enriched in Ras. J Cell Biochem 83(1):21-32 (DOI: 10.1002/jcb.1207)
- Goalstone ML, and Sadler SE (2000) Analysis of farnesyl transferase activity during hormone-induced maturation of Xenopus laevis oocytes. J Exp Zool 286(2):193-203 (DOI: 10.1002/(SICI)1097-010X(20000201)286:2<193::AID-JEZ11>3.0.CO;2-V)
- Goalstone ML, Diamond CL, and SE Sadler (1996) Characterization of Xenopus laevis oocyte farnesyl transferase. Biol. Reprod. 54:675-681.
