Research Interests

Cell biology, roles of tyrosine kinase and phospholipase C

Research Area

Dr. Stith and his lab found that insulin or progesterone addition to Xenopus oocytes increased tyrosine kinase activity and phospholipase C activity (phospholipase C produces IP3 which releases intracellular calcium, DAG which activates protein kinase C). First to successfully use an IP3 mass assay with Xenopus cells (two years in development), he provided the first report that fertilization involved an increase in the mass of IP3 (1993). He found another event in Xenopus fertilization: elevated calcium stimulated IP3 breakdown (use of intracellular calcium buffers resulted in a large increase in IP3 mass during fertilization). His lab also used these calcium buffers to prevent fertilization events but found that phospholipase C activity still incresed; this suggests that sperm do not elevate calcium to stimulate phospholipase C. The time course of phospholipase C activation found that the activity was high during the slow calcium wave (3 min to travel the egg from the sperm binding site)...this time course, and the measurement of IP3 mass, supports the idea that the calcium wave is due to a wave of elevated phospholipase C/IP3 production. As the lipid phosphatidic acid is also produced over this time, this lipid may also play a role in the calcium wave.

Current Members

Stith, Bradley J (Principal Investigator/Director) Contact

Contact

Institution: University of Colorado Denver

Address:
University of Colorado Denver
Denver, CO
USA