EXPRESSION OF AMPHIREGULIN IN THE SHEEP MAMMARY-GLAND

The reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify, from sheep mammary gland total RNA, a 280 bp sequence of a mphiregulin cDNA. Cloned and sequenced, it corresponded to the 78 amin o acids of the major secreted form of amphiregulin, showing 81, 70 and 69% identity with human, rat and mouse amphiregulin, respectively. Ex pression of amphiregulin was detected by RT-PCR in the mammary gland a t several developmental stages (fetal, lamb, early and late pregnant a nd lactating ewes) and in isolated myoepithelial cells. By Western blo tting with an antiserum to human amphiregulin, two molecular weight fo rms, 27 and 51 kDa were detected in sheep mammary gland microsomal pre parations, in a mammary gland extract after heparin affinity chromatog raphy and in a medium conditioned by mammary epithelial cells. By immu nocytochemistry, amphiregulin was detected in the cytoplasm and nuclei of luminal epithelial cells, myoepithelial cells and in intralobular stroma. An autocrine/paracrine role in sheep mammary growth is indicat ed. Copyright (C) 1997 Elsevier Science Ireland Ltd.