Development of replication-deficient adenoviruses as a tool in studying the role of membrane transport systems in cellular function
L O'Mullane, M Cummings, DI Cook, P Poronnik

In this project we have used replication-deficient adenoviruses to determine the mechanisms by which muscarinic and purinergic receptors control intracellular Ca²⁺ concentration in two epithelial cell lines, HSG cells and HT29 cells. We have found that in both HSG and HT29 cells, muscarinic receptors control intracellular free Ca²⁺ via the beta and gamma subunits of G_q. Purinergic receptors on the other hand, increase intracellular Ca²⁺ in these cells by the alpha-subunit of G_q. We are currently investigating the physiological significance of this difference in the G protein subunits that are used by the muscarinic and the purinergic receptors.

As part of this project we have also assisted other groups with the use of replication-deficient adenoviruses to investigate signal-transduction systems. We have assisted Professor J. Black (Department of Pharmacology) to use replication-deficient adenoviruses to determine the role of protein kinase C-zeta in the control of cell proliferation by bronchial smooth muscle cells. We have also assisted Dr E.A. Woodcock (Baker Institute, Melbourne) to investigate the role of G_q in signalling in cardiac muscle cells and Dr R. Baxter (Kolling Institute) in using adenoviral methods to produce large quantities of IGF-binding proteins for use in in vitro assays.