Developmental coordination of alpha-amylase and psp gene expression during mouse parotid gland differentiation is controlled posttranscriptionally.

We have compared the developmental expression of psp and Amy-1a genes during postnatal differentiation of the mouse parotid gland. The mRNAs encoded by both genes accumulate with identical kinetics and accumulate in the same subset of acinar cells early in development. Transcriptional activation of the two genes is unexpectedly asynchronous. While the increase of alpha-amylase mRNA levels in development arise from increased Amy-1a transcription, psp is transcribed at almost adult levels at 12 days of age, but cellular psp mRNA accumulation is very low. Since nuclear processing of psp pre-mRNAs and transport of mature mRNA into the cytoplasm occur with similar efficiencies in young and adult mice, the rapid turnover of psp mRNA in young animals occurs in the cytoplasm.