University of Colorado DenverCollege of Liberal Arts and SciencesUniversity of Colorado Denver

Bradley StithBradley J. Stith, Ph.D., Professor

Research Interests: Cell biology

Using frog (Xenopus) cells, we examine the role of lipid signaling in two fields of research: cell division and fertilization.  In cell division, we add insulin, IGF-1 or progesterone to oocytes to induce meiotic cell division and produce the "egg."  Hormones bind to receptors but the downstream actions are not fully described.  In this process, PIP2 (a lipid) is broken down by the enzyme phospholipase C, and that this increases two second messengers (IP3, which releases calcium, and DAG, which stimulates protein kinase C).  We have used the oocytes to examine insulin signaling and how an antidiabetic agents acts to help human patients.  Our second area of research involves adding sperm and  egg to induce fertilization.  We have recorded the increase in the second messengers noted above.  Our current emphasis involves an examination of how the enzymes that break down PIP2 or other lipids (e.g., by phospholipase D) are regulated.

Current Research Interests

  • Undergraduate Research.
  • How Insulin/Insulin-like Growth Factors induce Meiotic Cell Division.
  • Mechanism of the Anti-Diabetic Drug "Metformin"
  • How sperm activate eggs (fertilization).
  • Role of protein kinase C, receptor tyrosine kinases and lipids

Select Publications

1994- Stith, B.J., R. Espinoza, D. Roberts and T. Smart. Sperm increase egg inositol 1,4,5-trisphosphate mass in Xenopus eggs preinjected with calcium chelators or heparin. Developmental Biology 165:206-215.

1996- Stith, B.J., M.L. Goalstone, R. Espinoza, C. Mossel, D. Roberts, and N. Wiernsperger. The antidiabetic drug metformin elevates receptor tyrosine kinase activity and inositol 1,4,5-trisphosphate mass in Xenopus oocytes. Endocrinology 137:2990-2999.

1997- Stith, B.J., K. Woronoff, R. Espinoza, and T. Smart. Sn-1,2-diacylglycerol and choline increase after fertilization in Xenopus laevis. Molecular Biology of the Cell 8:755-765.

1998- Stith, B.J., K. Woronoff, and N. Wiernsperger. The antidiabetic drug metformin stimulates the intracellular portion of the human insulin receptor. Biochemical Pharmacology 55:533-536.

complete list of publications

Education

  • Ph.D., 1982. Washington State University
  • B.S., 1974. Ohio State University

Courses Taught

 

 

Office: NC 3402
Phone: 303.556.3371
Fax: 303.556.4352
E-mail: brad.stith@ cudenver.edu

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