title: The two promoters of the mouse alpha-amylase gene Amy-1a are differentially activated during parotid gland differentiation.
abstract: Mouse parotid acinar cells differentiate and proliferate mainly after birth. During the first 3 weeks of age, alpha-amylase mRNA, one of the major gene products of the adult tissue, increases from barely detectable to adult levels (10(4) copies/cell). Run-on transcription experiments show that this increase is transcriptionally regulated. Northern blot hybridization and in situ hybridization results indicate that the two promoters of the alpha-amylase gene Amy-1a are differentially switched on. First, the weaker downstream promoter is activated, and by 2 weeks of age, virtually all acinar cells have accumulated the transcript initiated at this promoter. At this age the strong Amy-1a promoter is utilized in only a minor proportion of acinar cells, while in the adult this promoter appears to be active in all acinar cells. Thus, the progressive accumulation of alpha-amylase mRNA during postnatal parotid differentiation is mainly the consequence of progressive acinar cell commitment to expression of the strong parotid-specific Amy-1a promoter. The pattern of committing cells during differentiation suggests that once an acinar cell has initiated expression of parotid-type alpha-amylase mRNA, this commitment is passed on to its daughter cells.
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D008099:Liver / Q000378:metabolism; D051379:Mice; D008805:Mice, Inbred A; D009693:Nucleic Acid Hybridization; D009876:Operon; D010306:Parotid Gland / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D010455:Peptides / Q000235:genetics; D021382:Protein Sorting Signals; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic; D000516:alpha-Amylases / Q000235:genetics*
chemical_list: D010455:Peptides; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D000516:alpha-Amylases