Identification and Expression of G_(01) and G_(02) #alpha#-Subunit Transcripts in Human Myometrium in Relation to Pregnancy

摘要

The 39-kDa G_0#alpha# protein, the #alpha# subunit of a major heterotrimeric G protein of brain and neuroendocrine cells, was found to be present in human myometrium. 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#_(01) and #alpha#_(02)), previously described in late pregnancy. To better ascertain the nature of these immunoreactive isoforms, we investigated transcripts of the G_0#alpha# gene in myometrium from pregnant and nonpregnant patients by reverse transcription-polymerase chain reaction (RT-PCR). In this tissue, the amplified cDNA product of a region common to both G_(01)#alpha# and G_(02)#alpha# mRNA variants was recognized as the G_0#alpha# nucleotide sequence. Transcripts of G_(01)#alpha# and G_(02)#alpha# were identified by sequencing. A partial cDNA G_(02)#alpha# sequence was described, which differed from the G_0#alpha# gene by two nucleotides in exon 8B. Levels of G_(01)#alpha# and G_(02)#alpha# transcripts analyzed by semi-quantitative RT-PCR were significantly higher in myometrium from pregnant than from nonpregnant patients. It is suggested that G_0#alpha# gene expression in this tissue may contribute to modifications seen in the signaling pathways observed at the end of pregnancy.