Isolation and Characterization of a Corticotropin-Releasing Hormone-Like Peptide From Human Placenta

Abstract

Immunoreactive CRH was detected in extracts of human term placentae [5.2 +/- 0.8 (+/- SE) pmol/g wet wt; n = 9]. Molecular sieve chromatography revealed three size classes of immunoreactive CRH. The major species eluted with the Kav of synthetic rat CRH; the minor species had apparent mol wt (MW) of 18,000 and 8,000. A placental CRH-(1-41)-sized peptide was isolated by fractional acetone precipitation, molecular sieve chromatography, and sequential reverse phase high performance liquid chromatography steps. This peptide had the same chromatographic behavior as did rat CRH in all high performance liquid chromatographic isolation steps as well as the same UV absorbance to immunoreactive CRH ratio after the final purification step. Purified placental CRH stimulated ACTH release from anterior pituitary tissue in a dose-dependent manner and was equipotent with synthetic rat CRH. Partial sequencing indicated that 32 amino acids of this peptide are identical to those of rat and human CRH (sequence deduced from genomic sequence), and comparative peptide mapping with rat CRH provided further evidence that the placental CRH-like peptide is very homologous if not identical to CRH. The high mol wt placental CRH fractions also were partially purified by acetone precipitation, immune affinity chromatography, and gel filtration. Neither of these materials [big form (MW, 18,000) or intermediate form (MWr, 8,000)] stimulated ACTH release from rat pituitary tissue in vitro. Limited trypsin digestion of the highest MW CRH, followed by gel filtration analysis, resulted in conversion to the smaller [8,000 MW-sized and CRH-(1-41)-sized] forms. The detection of a CRH-like peptide in placenta together with our previous demonstration of plasma immunoreactive CRH in pregnant women suggest that the placenta synthesizes and secretes CRH into the maternal circulation.

mRNA expression profiles for corticotrophin-releasing hormone, urocortin, CRH-binding protein and CRH receptors in human term gestational tissues determined by real-time quantitative RT-PCR

“…The high expression of the CRH gene observed in placenta is in agreement with earlier findings, which describe this organ as the main source of intrauterine CRH protein production (Shibasaki et al 1982, Goland et al 1988, Sasaki et al 1988, Glynn et al 1998). To date, the possible quantitative contribution of other gestational tissues to intrauterine CRH synthesis has hardly been addressed.…”

“…urocortin) and the expression of CRH receptors have been described in numerous peripheral tissues, e.g. placenta (Sasaki et al 1988, Florio et al 2000, endometrium (Gravanis et al 2001), lymphatic organs or immune cells (Baigent 2001) and skin (Slominski et al 2001). In the central nervous system, CRH attenuates inflammatory reactions via glucocorticoid action.…”

Potential Biochemical Markers for Preterm Labor: A Pilot Study in North India

“…The cause(s) of this increase in ACTH may include [3]. The synergistic stimulation of the feto-placental unit and the pituitary adrenal axis of both fetus and mother play a pivotal role in initiation of parturition [4,5]. Our study is in accordance with Makrigiannakis et al who demonstrated the role of serum ACTH levels as predictive marker for premature labor [6].…”

Psychobiological Stress and Preterm Birth

“…Levels rise exponentially as pregnancy advances, peaking during labor, and falling to very low or undetectable levels within 24 hours after delivery (Campbell et al, 1987;Chan et al, 1993;Goland et al, 1992;Sasaki et al, 1987;Wolfe et al, 1988). Placental CRH is identical to hypothalamic CRH in structure, immunoreactivity and bioactivity (Petraglia et al, 1989;Sasaki et al, 1988). However, in contrast to the inhibitory influence on the promoter region of the CRH gene in the hypothalamus, Fig.…”