Three different turkey luteinizing hormone receptor (tLH-R) isoforms II: characterization of differentially regulated tLH-R messenger ribonucleic acid isoforms in the ovary.
We have recently characterized three different, alternatively spliced, partial turkey LH receptor (tLH-R) cDNA isoforms by the combination of reverse transcription-polymerase chain reaction (RT-PCR) and 5'- and 3'-rapid amplification of cDNA ends. The first cDNA (intact form: tLH-R(intact)) showed 98% and 72-75% similarity with chicken and mammalian LH receptor sequences, respectively. The other two cloned cDNA isoforms (insertion and truncated forms: tLH-R(insert) and tLH-R(trunc)) could encode truncated soluble protein isoforms that lack the transmembrane region. Northern blot analysis detected two transcripts of 3.0 kilobases (kb) (tLH-R(intact)) and 1.5 kb (tLH-R(trunc)) in the turkey ovary but could not discriminate a third alternatively spliced transcript (tLH-R(insert)) due to the small 86-base pair difference in the size range of approximately 3.0-kb mRNAs. But with the combination of RNase protection assay, RT-PCR, and Northern blot analysis, three different alternatively spliced tLH-R mRNA isoforms were quantified. Differential expression of the tLH-R mRNA isoforms was demonstrated in ovarian stromal tissue during various reproductive stages and in the theca and granulosa layer through follicular development. To gain a better understanding of the physiological significance of the three different tLH-R isoforms, total RNA from the theca layer through follicular development after prolactin (PRL) treatment was analyzed by RT-PCR. PRL treatment for 8-14 days significantly increased the steady-state levels of total tLH-R mRNAs, including tLH-R(insert) and tLH-R(trunc) mRNAs, compared to those in nontreated controls. In contrast, the steady-state levels of tLH-R(intact) mRNA during the same period was not significantly changed when compared to that in nontreated controls. The present study shows that tLH-R transcripts are alternatively spliced in a tissue-specific manner in the turkey and that the mechanism may, in part, be controlled hormonally.
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Division of Animal Physiology, Department of Animal Science, University of Minnesota, St. Paul, Minnesota 55108, USA.
Kim
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El Halawani
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Foster
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D017398:Alternative Splicing; D000818:Animals; D015152:Blotting, Northern; D002645:Chickens; D018076:DNA, Complementary / Q000737:chemistry; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006107:Granulosa Cells / Q000737:chemistry; D006080:Ovarian Follicle / Q000502:physiology; D010053:Ovary / Q000737:chemistry*; D011388:Prolactin / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis*; D011974:Receptors, LH / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017385:Sequence Homology; D013799:Theca Cells / Q000737:chemistry; D014422:Turkeys / Q000235:genetics*
D018076:DNA, Complementary; D012333:RNA, Messenger; D011974:Receptors, LH; D011388:Prolactin