Medical Student Research Fellowship for Summer 2009

Mentor: Richard J. Auchus
Department: Internal Medicine/Endocrinology & Metabolism
Room number: Y9.308
Mail Code: 8857
Phone number: 8-6751
E-mail: richard.auchus@UTSouthwestern.edu
Project title: biochemistry, physiology, and genetics of human steroid biosynthesis

Human subjects IRB approved project number (where applicable): 0902-505, 1203-776, 1203-811, 052007-067

Animal subjects IRB approved project number (where applicable): N/A

Project Type basic research and patient-based research

Brief Description of Projects:

Basic:
We are interested in determining the biochemical principles and structural features that govern how hydroxysteroid dehydrogenases function in living cells as primarily oxidative or reductive enzymes. This project involves site-directed mutagenesis and modification of tissue culture conditions to alter the directional preference of these enzymes in vivo. We then perform detailed in vivo and in vitro enzymology studies and crystallography of the altered enzymes to understand why these changes are observed. We also study the steroid hydroxylases, which are cytochrome P450 enzymes, to determine the structural basis of enzyme activity and the mechanisms of allosteric activation by cofactor proteins.

Another project involves molecular derangements of human adrenal tumors leading to the autonomous production of catecholamines, cortisol, or aldosterone.

Clinical:
We are developing liquid chromatography/tandem mass spectrometry (LC-MS/MS) assays for serum mineralocorticoids to define the physiology and genetics of mineralocorticoid-dependent hypertension using the Dallas Heart Study. This study will lead to pharmacogenetic analysis in response to blood pressure medications.

Additional clinical projects include characterization of cohorts with primary aldosteronism and Cushing syndrome and improved diagnostic strategies for these disorders, including the use of mass spectrometry for steroid profiling in peripheral blood and adrenal vein specimens. We are also interested in modifier genes in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21OHD); allelism in the aldosterone synthase gene and hypertension; and new treatments of pituitary diseases. We have additional projects concerning the molecular genetic basis of familial hormone excess syndromes such as macronodular adrenocortical hyperplasia.

Previous Research Activities or Publications with Medical Students:
Tim C. Lee worked with me for a year after graduating college and during the summer after his first year in medical school (1996-1998). He and I developed our yeast system for studying enzymology of steroidogenic cytochromes P450 (Auchus et al 1998 J Biol Chem 273:3158-3165; Lee et al 1999 J Clin Endocrinol Metab 84:2104-2110). Tim received the Academic Pediatric Society/Society for Pediatric Research (APS/SPR) Student Research Award in 1999 for this work. Tim was chief resident in pediatrics at UCLA and is now in private practice.
Kavita Vyas, worked in my lab the summer of 2000, characterizing the biochemistry of fusion proteins to probe the mechanism of action of cytochrome b5 on CYP17. Kavita won the award for best poster at the 39th Medical Student Research Forum, which was presented at the Endocrine Society meeting in June 2001, and she is now an MS4 at Columbia and applying for residency in Internal Medicine.
Daniel Sherbet worked in my lab for 2 summers (2001-2002, characterizing a mutation in CYP17 that causes isolated 17, 20-lyase deficiency by a novel mechanism. Daniel's oral presentation at the 40th Medical Student Research Forum was selected as the best talk of the day. The work was presented at the Endocrine Society meeting in June, 2002 and published (Sherbet et al J Biol Chem 278:48563-48569). Daniel spent 2004-05 as a medical student research Fellow of the Howard Hughes Medical Institute studying hydroxysteroid dehydrogenases (HSDs). He and I have written a book chapter, a review article (Mol Cell Endocrinol 265-266:83-88), and a manuscript now under review about his HSD work. He is a first-year Cardiology fellow at UTSW.
Kristen Bruce, studied (-)-progesterone (the enantiomer of progesterone) as an inhibitor of CYP17 and CYP21 in 2001 and started our work on HSD directionality. Her work on (-)-progesterone was published (Auchus et al Arch Biochem Biophys 409:134-144). She is now in dental school.
David Stidd worked here in 2003. He synthesized deuterium-labeled steroids to measure kinetic isotope effects for CYP17 and CYP21, and he won an award for best basic science poster at the 42nd Medical Student Research Forum for this work. He came back to the lab for 6 months in 2006 to finish off his work, and we are in the process of writing a manuscript.
Andrew Brandmeier was a SURF student in 2003. He engineered mutations to change the directional preference of AKR1C9 (rat liver 3?-hydroxysteroid dehydrogenase), which was published in 2006 (Papari-Zareei et al Endocrinology 147:1591-1597). He is now an MD-PhD student at Indiana University.
Siareyah Rambally identified a mutation in a patient with 17?-hydroxysteroid type 3 deficiency in 2003. She also demonstrated that the magnitude of the directional preference for human 17?-hydroxysteroid type 1 in transfected cells was not fixed but could be varied by changes in culture medium that alter intracellular nicotinamide cofactor concentrations. She is co-author with Dan Sherbet on the review article in press and the manuscript in review. She is currently an internal medicine resident in Houston.
Neema Chokshi and Sarita Singeetham helped to organize our adrenal vein sampling serum bank, leading to an Endocrine Society abstract and now a manuscript (resubmitted with revisions to J Clin Endocrinol Metab) about new approaches to the diagnosis and understanding the physiology of primary aldosteronism. On the side, they sequenced the CYP17 gene from a patient with 17-hydroxylase deficiency and won an award for top clinical science poster at the 2006 MSRF. They are currently interns in medicine and pediatrics.
Nina Akbar was a QP-SURF student in 2006, and she performed enzyme kinetics for the 17?-hydroxysteroid dehydrogenase work that is under review. She is an MS1 at UTSW.
Roshan Morbia worked on CYP21A2 genotyping and adrenal vein sampling for macronodular adrenocortical hyperplasia. The latter work was presented as a poster at the Endocrine Society in 2008. Roshan is an MS3 at UTSW.
Zichun Feng worked on RODH, an enzyme with multiple HSD activities, making mutations and studying steady-state steroid distributions. Her work was also presented at the Endocrine Society in 2008, and she is an MS3 at UTSW. Her work also received a "best poster" award at the MSRF in 2008.
Yishan (Coral) Zhou was a SURF student in 2007. She performed kinetic isotope effect experiments on CYP17A1 and CYP21A2, work that is nearing completion. She is applying for graduate schools now.
Diane Meyer was a QP-SURF student in the lab during the summer of 2008, and she worked on the enzymology of RODH mutations in yeast microsomes. She is applying for MD-PhD programs now.