Heterotrimeric G proteins mediate signalling from 7 transmembrane domain receptors to a variety of intracellular effectors. Regulators of G protein signalling (RGS) are a novel family of proteins, that act as GTPase activating proteins. In the human myometrium signalling via G proteins may be altered during pregnancy and labour, suggesting a physiological role of G proteins in human gestation. Our aim was to investigate the expression of RGS proteins in the human myometrium. Ethics Approval from the local committee and written consent were obtained from all subjects prior to collection of samples.
Profiles for the expression of messenger RNA were performed for RGS1 to RGS16, in myometrium taken from non-pregnant women following hysterectomy (n=4), or at term caesarean section either prior to (n=5; non-labouring) or following the onset of labour (n=5; labouring). Quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) techniques using 32P incorporation were employed for this purpose.
The presence of RGS1 to RGS16 mRNAs were detected in the myometrium of non-pregnant and pregnant subjects. RGS2 and RGS5 mRNAs are the most abundant in the human uterine smooth muscle. RGS7 is not expressed in the myometrium. Differential mRNA expression of these proteins was demonstrated during pregnancy and correlated with the onset of labour. Following these initial findings, the physiological role of myometrial RGS proteins in mediating uterine contractility via signal transduction mechanisms in the myometrium needs to be further elucidated.