Stimulation of DNA synthesis by microinjection of diadenosine 5′,5‴-P 1, P 4-tetraphosphate (Ap 4A) into Xenopus laevis oocytes

Abstract

Ap 4A stimulated DNA synthesis when injected into oocytes. The stimulation was dramatically increased when an exogenous template was microinjected. Aphidicolin inhibited the effect of Ap 4A, supporting a role of DNA polymerase α in this process. No stimulation by Ap 4A was observed in microinjected eggs, nor ATP was able to mimic the in vivo effect of Ap 4A. Besides microinjected activated DNA, the stimulation by Ap 4A of DNA synthesis was also observed with poly dT and poly dT-poly dA as templates, while no effect was observed with poly dA-dT 12–18 and poly dC-dG 12–18. These results support a role of Ap 4A in the initiation of DNA synthesis.