Identification and expression of G(o1) and G(o2) alpha-subunit transcriptsin human myometrium in relation to pregnancy

The 39-kDa G(o)alpha protein, the a! subunit of a major heterotrimeric G pr otein of brain and neuroendocrine cells, was found to be present in human m yometrium. Using three different antisera, we showed its strong expression in myometrium from pregnant patients as compared to nonpregnant ones. This is in agreement with the high expression level of its two isoforms (alpha(o 1) and alpha(o2)), previously described in late pregnancy. To better ascert ain the nature of these immunoreactive isoforms, we investigated transcript s of the G(o)alpha gene in myometrium from pregnant and nonpregnant patient s by reverse transcription-polymerase chain reaction (RT-PCR). In this tiss ue, the amplified cDNA product of a region common to both G(o1)alpha and G( o2)alpha mRNA variants was recognized as the G(o)alpha nucleotide sequence. Transcripts of G(o1)alpha and G(o2)alpha were identified by sequencing. A partial cDNA G(o2)alpha sequence was described, which differed from the G,a r gene by two nucleotides in exon 8B. Levels of G(o1)alpha and G(o2)alpha t ranscripts analyzed by semi-quantitative RT-PCR were significantly higher i n myometrium from pregnant than from nonpregnant patients. It is suggested that G(o)alpha gene expression in this tissue may contribute to modificatio ns seen in the signaling pathways observed at the end of pregnancy.