Alternative promoter usage and differential expression of multiple transcripts of mouse Prkar1a gene

Prkar1a gene encodes regulatory type 1 alpha subunit (RI alpha) of cAMP-dependent protein kinase (PKA) in mouse. The role of this gene has been implicated in Carney complex and many cancer types that suggest its involvement in physiological processes like cell cycle regulation, growth and/or proliferation. We have identified and sequenced partial cDNA clones encoding four alternatively spliced transcripts of mouse Prkar1a gene. These transcripts have alternate 5' UTR structure which results from splicing of three exons (designated as E1a, E1b, and E1c) to canonical exon 2. The designated transcripts T1, T2, T3, and T4 contain 5' UTR exons as E1c, E1a + E1b, E1a, and E1b, respectively. The transcript T1 corresponded to earlier reported transcript in GenBank. In silico study of genomic DNA sequence revealed three distinct promoter regions namely, P1, P2, and P3 upstream of the exons E1a, E1b, and E1c, respectively. P1 is non-CpG-related promoter but P2 and P3 are CpG-related promoters; however, all three are TATA less. RT-PCR analysis demonstrated the expression of all four transcripts in late postnatal stages; however, these were differentially regulated in early postnatal stages of 0.5 day, 3 day, and 15 day mice in different tissue types. Variations in expression of Prkar1a gene transcripts suggest their regulation from multiple promoters that respond to a variety of signals arising in or out of the cell in tissue and developmental stage-specific manner.