Characterization of different sizes of rat luteinizing hormone/chorionic gonadotropin receptor messenger ribonucleic acids.

Abstract

The LH/CG receptor is uniquely expressed in the gonads of both sexes at specific stages of development. In ovaries, its expression marks particular steps of the ovulation cycle. An enigmatic aspect of expression of the LH/CG receptor is the dramatically diverse transcript sizes [from 7 to < 1 kilobase (kb)] and development-dependent expression of different sizes of mRNAs. It has been thought that mRNAs larger than 2.1 kb encode full-length receptors, whereas those smaller than 2.1 kb encode truncated receptor, because the full-length coding sequence is 2.1 kb. As a first step in elucidation of these diverse mRNAs and corresponding proteins, we have produced a series of cDNA clones and determined their DNA sequences and deduced the amino acid sequences of the resulting proteins. Our data demonstrate that variant mRNAs are produced by alternate splicing and polyadenylation, and they encode significantly shorter truncated receptor peptides. Surprisingly, many of these variant mRNAs are larger than 2.1 kb, and some are 4.2 kb. Some of them are polyadenylated in introns 3, 4, and 10. These alternate mRNAs were successfully expressed in 293 cells to produce receptor peptides 81, 116, and 294 amino acids in length compared to the wild-type receptor, which consists of 674 amino acids. Although these receptor peptides are not secreted, they are capable of binding the hormone, indicating the presence of a hormone contact site(s) in the short peptide fragments, particularly the N-terminal 81-amino acid segment. The data presented here will be helpful for understanding the functions of different sizes of mRNAs and also be valuable in studies designed to investigate whether individual cells express a specific message or multiple messages and how different classes of LH/CG receptor mRNAs are selectively expressed dependent on differentiation and development of the gonads.

Effects of Vertically Transferred 3,3',4,4',5-Pentachlorobiphenyl on Gene Expression in the Ovaries of Immature Sprague-Dawley Rats

“…While the precise causes of this discrepancy are unclear, it is possible that vertically transferred PCB-126 targets granulosa cells in the antral follicle, which are in the early stages of development around PND 15. Previous studies have reported that there are multiple variants of transcripts in the LH receptor gene [26] and that mRNA encoding the full-length LH receptor is expressed concomitantly with the appearance of differentiated theca cells [27]. In the present study, we quantified LH receptor mRNA using a primer set corresponding to a region from exons 8 to 9 of the LH receptor gene [26].…”

“…Previous studies have reported that there are multiple variants of transcripts in the LH receptor gene [26] and that mRNA encoding the full-length LH receptor is expressed concomitantly with the appearance of differentiated theca cells [27]. In the present study, we quantified LH receptor mRNA using a primer set corresponding to a region from exons 8 to 9 of the LH receptor gene [26]. Although the primer set could amplify the truncated form of the receptor mRNA, the ovaries produced follicles with differentiated theca cells from PND 15 onwards.…”

Engineering the Human Thyrotropin Receptor Ectodomain from a Non-secreted Form to a Secreted, Highly Immunoreactive Glycoprotein That Neutralizes Autoantibodies in Graves' Patients' Sera

“…Whether the complex carbohydrate comprises part of the epitope(s) for TSHR autoantibodies or whether lack of autoantibody recognition of the "high mannose" ectodomain is secondary to incorrect polypeptide folding (and, hence, retention in the endoplasmic reticulum) (42,43) is presently unknown. It is of interest (and paradoxical) that COOH-terminal truncation of the LH/CG receptor ectodomain at a position (amino acid residue 294) similar to the TSHR variants generates a non-secreted protein (44). On the other hand, the LH/CG receptor truncated at residue 329 or further downstream is secreted to a limited extent (45,46).…”

Molecular cloning of a novel luteinizing‐hormone/ human‐chorionic‐gonadotropin‐receptor cDNA

“…Thus, the long 3' UTR we have identified may be involved in the degradation of lutropinlchoriogonadotropin-receptor mRNA in response to pharmacological doses of hormone and appears to be consistent with observations in the peptidylarginine deiminase system. A recent publication by Koo et al [38] has described the cloning of lutropidchoriogonadotropin-receptor transcripts of varying sizes. However, the 3.5-kb cDNA that we have described is not accounted for in their study.…”