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Minoru Tanaka, Yukinobu Hayashida, Tadashi Iguchi, Nobuhiro Nakao, Maiko Suzuki, Naoya Nakai, Kunio Nakashima, Identification of a Novel First Exon of Prolactin Receptor Gene Expressed in the Rat Brain, Endocrinology, Volume 143, Issue 6, 1 June 2002, Pages 2080–2084, https://doi.org/10.1210/endo.143.6.8826
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Abstract
A novel first exon, E14, whose sequence was distinct from those of the three known first exons, E11, E12, and E13, of the rat PRL receptor (PRL-R) gene was identified by cDNA cloning for the 5′-end region of PRL-R mRNA expressed in the rat brain. Sequence analysis revealed the presence of two different length E14 cDNAs. The longer cDNA contained the 243-bp E14 sequence, and the shorter cDNA lacked the 139-bp sequence at the 5′-end of the longer one. Neither E14 cDNA has a second exon sequence, indicating that the E14 first exon is extensively spliced to the third exon. E14-containing PRL-R mRNAs were detected only in the brain by RT-PCR and ribonuclease protection assay. The longer E14 mRNA was expressed as the major PRL-R mRNA species in the brain and was greatly increased in pregnant (d 18) and lactating (d 5) rats. A genomic clone containing the E14 first exon together with its 5′- and 3′-flanking regions was isolated from a rat kidney genomic library. Ribonuclease protection assay revealed that the position corresponding to the 5′-end of the shorter E14 cDNA is the major transcription start point for the E14 exon. The 5′-flanking region of E14 contained a TATA box-like element 23 bp upstream of the major transcription start point. Other putative transcription factor-binding sites, such as CCAAT, Sp1, and glucocorticoid-responsive elements, were observed at further upstream regions. These results suggest that PRL-R gene expression in rat brain is controlled by the promoter for the E14 first exon.
