Endocrine Abstracts (2007) 14 P620

LH receptor gene expression and splicing variants in marmoset (Callithrix jacchus) testis and adrenal gland at puberty

Caroline Michel, Jörg Gromoll, Ramesh Chandolia & Manuela Simoni

Institute of Reproductive Medicine, Muenster, Germany.

Background: The LHR is a crucial mediator for normal sexual development and fertility. In the marmoset monkey (Callithrix jacchus), LHR type II, lacking exon 10, is the native receptor type. In addition to the testis, the LHR is expressed in the adrenal gland where its function remains unknown.

Aim: To characterise marmoset LHR expression at different stages of puberty in the testis and adrenal gland and examine different splice variants in the testis.

Material and methods: We analysed 25 male marmosets of five age groups (n=5/group): 21.5±0.1, 43.3±0.7, 52.8±0.3, 70.1±0.4 and 116.8±20 weeks (mean±S.E.M.). Total RNA was isolated from testes and adrenal glands, reverse-transcribed and used for real-time PCR. Splice variants were detected using primers directed to exon 2 and 11. PCR products were analysed by densitometric analysis, cloned into pGEM-T-Easy-vector and sequenced.

Results: The expression levels of the full transcript were lowest at the beginning of puberty and increased progressively both in the testis and in the adrenal gland. The full-length transcript expression values in the testis (2.244±0.9 AU) were 4.2-fold higher compared to the adrenal gland (0.537±0.5 AU). We detected eleven LHR splicing variants in the testes. Seven of these showed exon skipping, lacking one to seven exons, and four were alternatively spliced. As expected, exon 10 was absent in all variants. While each variant is expressed 0.7-fold, the overall amount of all splice variants is much more abundant (6.1±0.5) than the wild type. Two thirds of all isoforms lack four or less exons and densitometric analysis recognized no pubertal-associated variance. Alternative splicing was much less evident in the adrenal glands.

Conclusion: LHR expression increased progressively in both tissues while the splicing patterns itself does not change during puberty, and different splice variants exist in the testis.

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