COORDINATED EXPRESSION OF SPLICE VARIANTS FOR LUTEINIZING-HORMONE RECEPTOR MESSENGER-RNA DURING THE DEVELOPMENT OF BOVINE CORPORA-LUTEA

We characterized splice variants for LH receptor mRNA in the bovine co rpus luteum and examined the levels of expression of all the splice va riants during the development of corpus luteum. Total RNA was extracte d from bovine corpora lutea, and reverse transcriptase-polymerase chai n reaction (RT-PCR] was performed to amplify a part of the extracellul ar and transmembrane domains. As a result, four distinct bands were ob served on analyses with polyacrylamide gel electrophoresis, and sequen cing of the products revealed that the largest form (519 bp) was the f ull-length A form and that the three shorter forms [438, 253, and 172 bp) were its splicing variants. Splicing patterns of the 438-, 253-, a nd 172-bp forms are identical to the F, B, and G forms, respectively, found in the ovine ovary. In order to examine the level of expression of all these splice variants simultaneously, semiquantitative RT-PCR w as set up and performed. The relative intensities for all four forms o f LH receptor mRNA significantly increased (P < 0.05) from Stage I (Da ys 1-4; Day 1 = day of ovulation) to IIS (Days 5-10, CL weight < 4 g), and from Stage IIS to IIL (Days 5-10, CL weight greater than or equal to 4 g). The intensities of all forms for LH receptor mRNA decreased slightly, but not significantly, from Stage IIL to III (Days 11-17). T he ratios of the levels for all the forms did not change significantly during the development of the corpus luteum. Determination of the ste ady-state levels of LH receptor mRNA by Northern blotting showed simil ar changes during the development of the corpus luteum to changes of t he splice variants examined by the semiquantitative RT-PCR. These resu lts suggest that at least three splicing variants of LH receptor mRNA (i.e., F, B, and G forms) exist in the bovine corpus luteum and that t he levels of all the forms of LH receptor mRNA increased in a coordina ted manner during the development of bovine corpus luteum. Mel. Reprod . Dev. 51:66-75, 1998. (C) 1998 Wiley-Liss, Inc.