Expression of exon 3-retaining and -deleted human growth hormone receptor messenger ribonucleic acid isoforms during development

Recent investigations have suggested that human GH (hGH) and its receptor may have specific functions during human fetal life. To improve our understanding of the mechanisms of hGH action during gestation, we characterized the ontogenic appearance of hGH receptor messenger ribonucleic acid (mRNA) in multiple human fetal and postnatal tissues. Using RT-PCR assays, followed by Southern hybridization to confirm the specificity of the amplified fragments, we scanned the entire coding region of the hGH receptor mRNA. Transcription of the hGH receptor gene was observed in all fetal tissues studied (liver, kidney, skin, muscle, lung, adrenal, spleen, intestine, central nervous system, pancreas, and placental villi) from the earliest stage that could be examined [7-14.8 weeks fetal age (FA)]. Furthermore, we identified only 2 isoforms of the hGH receptor mRNA-coding region: exon 3 can be retained or deleted. Surprisingly, we found individual-specific, not tissue-specific, expression patterns of these two transcri...