Cindy Benod

The liver receptor homologue-1 (LRH-1, NR5A2), an orphan nuclear receptor, regulates important steps of development, endocrine homeostasis and metabolism. Recent studies also demonstrate that LRH-1 was found at high levels in breast tumor cells and surrounding adipose tissue. Furthermore, in breast cancer cells uniquely, LRH-1 powerfully enhances expression of aromatase, the only enzyme that converts androgen to estrogen, stimulating tumor progression in estrogen positive cells. As a consequence, blocking LRH-1 transcriptional activity in breast cancer cells should slow or eliminate tumors and may provide a more selective therapeutic strategy to treat breast cancer.

Cindy’s work is dedicated to employing an innovative screen to identify compounds that exclusively inhibit the LRH-1 transcriptional activity in breast cancer cells. She has a fellowship from the California Breast Cancer Research Program.

Leslie Cruz

Leslie’s project is to probe the behavior mediated by androgen receptor in brain. She is working in collaboration with Professor Nirao Shah, who will construct transgenic mice that express an engineered androgen receptor, which only responds to a unique testosterone derivative that Leslie will design, synthesize and test. Leslie has already obtained one unique testosterone for testing and is designing a variant androgen receptor that will only respond to this testosterone analog.

She has also designed a second series of testosterone analogs (at the C17 position) and will synthesize and test these, if the current compound fails in animal trials. The ultimate goal of this research is to make compounds that are tissue specific so that we can learn the roles of the receptor in muscle, bone, prostate and brain. Therapeutics that spare other tissues, while effectively blocking androgen receptor in prostate, may be designed from Leslie’s research results.

 

Ariel Gragnolati

Structural and functional interactions between the endocytic and steroid receptor signaling pathways

Peter Hwang

is studying the androgen receptor (AR) and its associations with coactivator proteins. His project is to define critical interactions between the SRC family of coactivators with the N terminal domain of the androgen receptor and to develop the structural basis for first drug candidates that block androgen receptor function by disrupting these interactions.

Kris Kuchenbecker

Sam Pfaff

The glucocorticoid receptor mediates the cellular response to corticosteroids by activating and repressing target gene transcription. A vital step in its action is the binding of co-regulator proteins once inside the nucleus. Steroid and co-regulator binding occur at two regions of the ligand binding domain that are allosterically coupled. Our research investigates the mechanism of coupling between sites with purified components using various biophysical methods.

Elena Sablin

focuses on two enigmatic orphan nuclear receptors, LRH-1 and SF-1, and their physiological regulatory partner, orphan nuclear receptor Dax-1. Dax-1 is indispensable in embryogenesis and vital for maintenance of pluripotent state of ES cells. Because of its critical role in human development and physiology, Dax-1 is the central target of current studies. We recently expanded the study of regulatory mechanisms by Dax-1 to Nanog, a key transcriptional regulator and marker of the pluripotent state of embryonic stem (ES) cells.

In collaboration with Dr. Holly Ingraham (UCSF), we have determined the crystal structures of the ligand binding domains (LBDs) of LRH-1 and SF-1 to 2.4 Å and 1.2 Å resolution, respectively. These structural studies suggested a model for constitutive transcriptional activity of these receptors and revealed phosphatidyl inositols as potential functional ligands for LRH-1 and SF-1. We have also determined the first structure of Dax-1 in a trimeric complex with its physiological  target, LRH-1. This unusual trimeric assembly might explain how Dax-1 regulates multiple partners in reproductive tissues and embryonic stem cells.

Sablin EP, Blind RD, Krylova IN, Ingraham JG, Cai F, Williams JD, Fletterick RJ, and HA Ingraham (2009) Structure of SF-1 bound by different phospholipids: evidence for regulatory ligands. Mol Endocrinol. 23, 25-34.

Sablin EP, Woods A, Krylova IN, Hwang P, Ingraham HA, and R.J. Fletterick (2008) The structure of corepressor Dax-1 bound to its target nuclear receptor LRH-1. Proc Natl Acad Sci USA 105, 18390-5.  

Krylova IN., Sablin EP, Moore J, Xu RX, Waitt GM, McKay JA, Juzumiene D, Bynum JM, Madause K, Montana V, Lebedeva L, Suzawa M, Williams JD, Williams SP, Guy RK, Thornton JW, Fletterick RJ, Willson TM and HA Ingraham (2005) Structural analyses reveal phosphatidyl inositols as ligands for the NR5 orphan receptors SF-1 and LRH-1. Cell 120, 343-355.

Sablin EP, Krylova IN, Fletterick RJ, and HA Ingraham (2003) Structural basis for ligand-independent activation of the orphan nuclear receptor LRH-1.  Mol Cell 11, 1575-85.

Fumiaki Yumoto

obtained his PhD from the Univ. of Tokyo and joined theFletterick lab in 2007. He studies the molecular mechanisms of the synergy between the nuclear receptor, LRH-1, and beta-catenin using X-ray crystallography. This structure-function study is in progress in collaboration with the labs of Dr. Paul Webb of The Methodist Hospital Research Institute (TMHRI) in Houston. Fumiaki is interested in stem cell biology and because LRH-1 is an up-regulator of Oct4 expression in embryonic stem cells (ES cells), it contributes to maintaining the pluripotent state. Fumiaki has expanded his research to identify LRH-1-interacting molecules from mouse ES cells by mass spectrometry-based proteomics through collaboration with Nevan Krogan’s lab at UCSF. Fumiaki was awarded a postdoctoral research fellowship from the Sandler Program for Breakthrough Biomedical Research (UCSF) for this project. He is also working on a collaborative study on cell reprogramming with the labs of Dr. Bruce Conklin and Dr. Shinya Yamanaka at the Gladstone Institute for Cardiovascular Disease.

 

Maia Vinogradova

works on the regulation of the kinesin motor. Her two projects on kinesin regulation
are : 1) crystallization of the kinesin-like calmodulin binding protein (KCBP) in the complex with its regulator, either calmodulin or a novel single EF-hand, plant specific protein KIC, and 2)  crystallization of the complex of the kinesin CENP-E and its cargo binding protein – protein kinase BUBR1 which is involved in mitotic checkpoint.

Maia is also studying the skeletal muscle ternary complex in both relaxed and calcium-activated forms. The goal of this project is to find a drug capable of increasing the muscle strength and Ca2+-sensitivity of muscle contractions.

Maia previously determined the structure of troponin with and without calcium.

Vinogradova MV, Malanina GG, Reddy AS, Fletterick RJ. (2009)  Structure of the complex of a mitotic kinesin with its calcium binding regulator.  Proc Natl Acad Sci U S A. May 19; 106(20):8175-9.

Vinogradova M, Malanina G, Reddy V, Reddy A and RJ Fletterick. (2008)  Structural dynamics of the microtubule binding and regulatory elements in the kinesin-like calmodulin binding protein. J Structural Biology 2008 J Struct Biol. 2008 Jul;163(1):76-83.

Vinogradova MV, Stone DB, Malanina GG, Mendelson RA, Fletterick RJ. (2007) Ca ion and the troponin switch. Adv Exp Med Biol.592:47-57. Review.