Endocrine Abstracts

Prostaglandins are strongly implicated in the onset and maintenance of human parturition and their synthesis is increased within the uterus in association with labour. Enzymes involved in their synthesis, (cyclo-oxygenase-2), and catabolism, (prostaglandin dehydrogenase) are up and down-regulated respectively, in association with labour. The human prostaglandin dehydrogenase (PGDH) gene is approximately 34kb in size. A large 5' promoter region containing numerous potential transcription factor-binding sites implicates transcriptional regulation. Alternative splicing of the PGDH gene has been demonstrated in carcinoma cell lines and results in C-terminally truncated mRNA. The aims of this study were to identify the presence of PGDH splicing isoforms within pregnant uterine tissues. Tissue; Fetal membranes and placenta were collected, between 28 and 37 weeks at elective caesarean section prior to labour onset, and after 38 weeks both prior to and following labour. Myometrial tissue was collected from the upper margin of uterine incision at time of lower segment caesarean section from full term pregnancies. Ethics committee approval and consent were obtained prior to all tissue collection. Methods; RNA was isolated using a guanidine isothyocyanate and phenol-chloroform extraction technique. Reverse transcription polymerase chain reaction (RT-PCR) was used for semi quantitative analysis of RNA expression. RT was carried out using random hexanucleotide primers, and the resultant cDNA used as template for PCR. RT-PCR products were analysed by gel electrophoresis and verified by sequence analysis. Results; We identified expression of three PGDH isoforms within chorio-decidua (824, 660 and 583bp), and two in placenta (824 and 660bp), generated by alternative splicing of the gene. Only the large transcript was observed within pregnant myometrium. Conclusions; The alternatively spliced isoforms are C-terminal truncated forms of the PGDH gene and may represent another level of gene regulation within these tissues. How these isoforms correlate with PGDH enzyme activity remains to be determined.