Reciprocal expression of c-jun, proline-rich protein and amylase genes during rat parotid salivary gland development.
We have investigated the temporal expression and cellular localization of the c-jun proto-oncogene and two major rat parotid gland secretory protein genes, PRP (proline-rich protein) and amylase, during postnatal development. c-jun mRNA steady-state levels increased at days 1, 7 and 14 after birth and decreased to basal levels at 21 days and older. PRP mRNA was first detected at 14 days and abruptly increased to adult levels at day 21. Amylase transcripts were first seen at day 7 and progressively increased to adult levels by 28 days. In situ hybridization demonstrated c-jun mRNA accumulation in the differentiating acinar cells and the ducts. The c-jun mRNA accumulation with time corresponds with the proliferative activity reported to occur in these two cellular populations. PRP transcripts were present exclusively in the well differentiated acinar cells while the accumulation of amylase mRNA corresponded to the progressive commitment of parotid cells to acinar differentiation. Our data suggest that during the postnatal development of the rat parotid gland: (a) c-jun expression associates with parotid gland proliferation and precedes the expression of PRP and amylase genes, and (b) activation of PRP and amylase genes is not concomitant and apparently occurs only in differentiating acinar cells.
D000367:Age Factors; D000681:Amylases / Q000235:genetics*; D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics; D051766:Early Growth Response Protein 1; D015870:Gene Expression; D016758:Genes, jun; D017874:Immediate-Early Proteins; D010306:Parotid Gland / Q000254:growth & development* / Q000378:metabolism; D010455:Peptides / Q000032:analysis*; D055232:Proline-Rich Protein Domains; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D014157:Transcription Factors / Q000235:genetics
D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D010455:Peptides; D012333:RNA, Messenger; D014157:Transcription Factors; D000681:Amylases