Temporal Effects of Prolactin on Casein Kinase Activity, Casein Synthesis and Casein mRNA Accumulation in Mouse Mammary Gland Explants

Summary

Studies were carried out to investigate the mechanism by which prolactin stimulates casein synthesis in cultured mouse mammary tissues. The onset of the prolactin stimulation of casein synthesis occurs 8-10 hours after prolactin addition to cultured tissues; a maximum effect is evoked by 16 hours. A similar time-course of response to prolactin was observed when the tissue accumulation of the mRNA for β-casein was determined. At 16 hours, however, prolactin had no effect on tissue-specific casein kinase activity which is associated with the Golgi apparatus. These studies suggest that the tissue content of casein mRNA is causally related to the onset of the prolactin stimulation of casein synthesis in cultured mouse tissues. In contrast, the activity of the kinase that catalyzes the phosphorylation of the caseins is not altered by prolactin and thus apparently is not a contributing factor to the early prolactin effect on casein synthesis.

Key words

Casein Kinase - Galactosyl Transferase - Casein Synthesis - Casein mRNA - Mammary Gland - Prolactin