Cloning of Bovine Eukaryotic Translation Initiation Factor 4E (eIF-4E) and Its Expression in the Bovine Mammary Gland at Different Physiological Stages

Bovine eIF-4E cDNA was cloned and its expression in the bovine mammary gland at distinct physiological stages was investigated. Bovine eIF-4E cDNA and protein sequences are highly homologous to those from other mammals. Using Northern blot analysis, we did not detect eIF-4E expression in the prepubertal bovine mammary gland, whereas a low level of eIF-4E mRNA was observed in the mammary tissues of heifers during the third estrous cycle. The eIF-4E mRNA level was significantly higher in the lactating mammary gland compared to the mammary tissues obtained from heifers during the third estrous cycle. Alteration of eIF-4E expression in bovine mammary tissues during different physiological stages indicates the involvement of eIF-4E in mammary development. Elevated eIF-4E expression during lactation may be related to increased translation of certain mRNA or the acceleration of overall protein synthesis.