Regulation of proto-oncogenes and salivary gland cell proliferation

• Published in: Advances in dental research Vol. 4; p. 61
• Main Authors: Kousvelari, E, Yeh, C K, Mertz, P M, Chinchetru, M
• Format: Journal Article
• Language: English
• Published: United States 01.06.1990
• Subjects: 8-Bromo Cyclic Adenosine Monophosphate - pharmacology; Animals; Cell Division - genetics; DNA-Binding Proteins - genetics; Gene Expression Regulation; Male; Parotid Gland - cytology; Parotid Gland - growth & development; Promoter Regions, Genetic; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-jun; Proto-Oncogenes - physiology; Rats; Rats, Inbred Strains; Receptors, Adrenergic, beta - physiology; Transcription Factors - genetics; Transcription, Genetic
• ISSN: 0895-9374
• DOI: 10.1177/08959374900040010901

The proto-oncogenes c-fos and c-jun express proteins targeted into the nucleus. The fos and jun proteins form a heterodimeric complex that binds to regulatory elements in the promoter region of specific genes to influence their transcription. Through such a mechanism, the fos and jun proteins have been suggested to link extracellular stimuli to short- and long-term functional changes in cells. Recently we have shown that beta-adrenergic receptor stimulation of rat parotid acinar cells in vitro or addition of 8-BrcAMP in a rat submandibular cell line (RSMT-A5) increases the expression of the c-fos gene in a time-dependent manner. Maximal responses were found at 60 min. The expression of the c-fos gene did not correlate with DNA synthesis in either cell type, and c-fos transcripts were undetectable in the glands of animals treated for eight days with isoproterenol. The new data presented here extended our observations to c-jun gene expression in both salivary cell types where a similar pattern of expression for this proto-oncogene was seen. Conversely, treatment of rats with isoproterenol for nine days resulted in the appearance of two c-abl mRNAs of unique size, in addition to the known 5.3-kb c-abl transcripts. The data suggest that beta-adrenergic receptor stimulation or exposure to 8-BrcAMP induces the early expression of the "nuclear proto-oncogenes" c-fos and c-jun before changes are noted in salivary epithelial cell proliferation. Differences in c-abl mRNA size, occurring later, may be associated with the morphological and biochemical changes known to occur in rat parotid glands after chronic beta-adrenoreceptor stimulation.