6-Dimethyl amino purine and 2-amino purine inhibit the induction of expresion of milk protein genes by prolactin

Two protein kinase-inhibitors, 6-dimethyl amino purine and 2-amino purine inhibited induction of -casein synthesis by prolactin when added to the culture medium of rabbit mammary explant and cells. The accumulation of the mRNA for _s1- and -caseins and for whey acidic protein did not take place in the presence of the inhibitors whereas -actin mRNA concentration was not altered. In the same experimental conditions, H7, an inhibitor of protein kinase C and, to a lower extent, of protein kinase A did not prevent prolactin from acting. These data suggest for the first time that specific protein kinases are involved in the transduction of the prolactin signal to milk protein genes.Abbreviations 6-DMAP 6-dimethyl amino purine - 2-AP 2-amino purine - H7 1-(5 isoquinoline sulfonyl)-2-methyl-piperazine dihydrochloride - WAP whey acidic protein - PRL prolactin