Two novel first exons in the prolactin receptor gene are transcribed in a tissue-specific and sexual maturation-dependent manner to encode multiple 5'-truncated transcripts in the testis of the chicken.
Cloning and sequencing of the chicken prolactin receptor (PRLR) gene segment from the transmembrane domain to the box 2 motif revealed the presence of the two testis-specific first exons, TSE-1 and TSE-2, encoding the unique 5'-end sequences of the reported and newly identified multiple 5'-truncated PRLR transcripts containing only the cytoplasmic domain in the testis. TSE-1 was located downstream of the exon encoding the transmembrane domain and TSE-2 presented downstream of the exon encoding the box 1 motif. These findings indicate that the box 1-containing 5'-truncated transcripts are generated by the utilization of TSE-1 as the first exon with distinct splicing donor sites to the box 1-containing exon, and that the utilization of TSE-2 as the first exon and its splicing to the box 2-containing exon results in the generation of the box 1-lacking transcript. Three transcription initiation sites for the box 1-containing 5'-truncated transcripts and two transcription initiation sites for the box 1-lacking transcript were detected by the RNase protection assays. Reverse transcription-polymerase chain reaction analysis showed that the expression levels of all these 5'-truncated PRLR transcripts are simultaneously increased during sexual maturation, accompanying the decrease of the amount of the canonical full-length transcript for PRLR.
Tanaka
M
M
Department of Biochemistry, Faculty of Medicine, Mie University, 2-174 Edobashi, Tsu, Mie, Japan.
Yamamoto
I
I
Hayashida
Y
Y
Nakao
N
N
Ohkubo
T
T
Wakita
M
M
Nakashima
K
K
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002645:Chickens / Q000235:genetics* / Q000254:growth & development; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons; D008297:Male; D008969:Molecular Sequence Data; D011981:Receptors, Prolactin / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012741:Sexual Maturation; D013737:Testis / Q000378:metabolism*; D014158:Transcription, Genetic
D018076:DNA, Complementary; D011981:Receptors, Prolactin