Molecular characterisation of the gene, LGALS13, and its putative involvement in pre-eclampsia

[摘要] Pre-eclampsia is one of the most common hypertensive disorders ofpregnancy in South Africa. Presently, the only cure for pre-eclampsia isdelivery, which brings with it, additional complications. As an alternative,clinical management of this disorder relies on timely diagnosis.The predictive biomarker, Placental Protein 13 (PP13), is currently usedfor the early diagnosis of pre-eclampsia, in an ELISA-based diagnostickit, developed by Diagnostic Technologies Limited (DTL)1. A decrease inserum PP13 levels has been reported during the first trimester ofpregnancy in women who later develop pre-eclampsia. The function ofPP13 has not been fully elucidated and it is also not known whether thereduction in PP13 levels is a cause or an effect of the disease. The useof PP13 as a predictive biomarker for pre-eclampsia therefore warrants acomprehensive study of this peptide and the encoding gene, LGALS13.The aim of this study was firstly to characterise LGALS13 using a rangeof in silico tools. PP13 was found to be most homologous to thepredicted protein product of a neighbouring 'putative gene, LOC148003.A gene conversion event between these two genes most likely underliesthe so-called 'hotspot mutation in LGALS13. Data also demonstratesthat the DelT mutation disrupts functionally and structurally importantfeatures of the gene and peptide sequences. Through the analysis of theputative promoter region of LGALS13, the presence of a Stimulatoryprotein-1 (Sp1) binding sequence element was predicted, which hasimplications for regulation of LGALS13.Secondly, the study aimed to establish a study cohort for theinvestigation of the effect that the LGALS13 genotype has on theexpression of its mRNA and protein products. Serum, plasma and whole blood samples were collected and prepared from 316 pregnant women.Placental tissue samples were obtained from a selected group of thesesubjects for RNA extraction. Once the sampling on the two remainingtargeted deliveries has occurred, the collection of samples will bebatched and sent to DTL in Israel, for PP13 measurement.DNA was extracted from the whole blood samples obtained, and allstudy participants were genotyped for seven sequence variants withinthe LGALS13 gene using (i) Multiphor Single Stranded ConformationalPolymorphism and Heteroduplex (SSCP/HD) analysis, (ii) restrictionenzyme analysis and (iii) DNA sequencing. The genotype data sets willbe compared with PP13 levels when they become available, and alsowith clinical parameters, once the deliveries have all occurred and thedatabase is complete.This study demonstrated the power of an in silico approach to direct thefocus of future experimental work. The newly established study cohortwill be used for prospective studies aiming at a better understanding ofthe role which LGALS13 and PP13 play in the early prediction of preeclampsia.

[发布机构] Stellenbosch University