cAMP constitutes a suffficient mitogenic signal for a variety of mammalian cells. The cAMP mitogenic cascade is unique in that it often induces differentiation, in addition to proliferation. However, little attention has been paid to this pathway, as opposed to the better studied tyrosine kinase and protein kinase C cascades.
The present project seeks the cloning and characterization of new protooncogene(s) and/or antioncogene(s) associated to the cAMP mitogenic pathway, using the TSH/thyrocyte model system. The study will be conducted according to the following objectives:
1. Identification of cAMP-regulated genes involved in the TSH mitogenic pathway. This will be performed by differentially screening cDNA libraries from stimulated cells using probes derived from quiescent cells. 2. Sequencing and quinetics of expression of cAMP-controlled cell cycle regulatory genes. Assessment of their role. A regulated, cell-cycle dependent expression will be analized. Sequences of the selected clones will be compared to those of known families.
3. Definition of the role of identified genes in the control of cell proliferation. The protein encoded for by the selected genes wili be expressed in appropiate expression system. Its function will be analyzed in the relevant cell-free systems. Gene expression in normal and malignant tissues will be compared.