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Regulation of proline‐rich protein and α‐amylase genes in parotid‐hepatoma hybrid cells

Salivary proline‐rich proteins are encoded by tissue‐specific multigene families, and are dramatically induced in mice, rats, and hamsters by treatment with the β agonist isoproterenol. Salivary gland cells, however, are difficult to maintain in a differentiated state in culture and can be induced to synthesize proline‐rich protein mRNAs for only a few days. In an attempt to establish a cell line in which it would be possible to regulate proline‐rich protein gene transcription, rat parotid gland cells were fused with the rat hepatoma cell line, FTO‐2B. Fused cells were obtained that had a frequency of 7.5 times 10−6, which is about 125‐fold greater than the reversion rate of FTO‐2B. The hybrid cells exhibited induced proline‐rich protein mRNA synthesis when incubated with either dibutyryl cyclic AMP or forskolin. The ability to induce these genes was maintained for at least 20 passages. Most of the fused cell populations also synthesized elevated levels of α‐amylase mRNA, another tissue‐specific gene.— Wright, P. S.; Carlson, D. M. Regulation of proline‐rich protein and α‐amylase genes in parotidhepatoma hybrid cells. FASEB J. 2: 3104‐3107; 1988.