Processing of Procorticotropin-Releasing Hormone (Pro-CRH): Molecular Forms of CRH in Normal and Preeclamptic Pregnancy

I Ahmed; B. P Glynn; A. V Perkins; M. G Castro; J Rowe; E Morrison; E. A Linton

doi:10.1210/jcem.85.2.6351

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Processing of Procorticotropin-Releasing Hormone (Pro-CRH): Molecular Forms of CRH in Normal and Preeclamptic Pregnancy

Journal article

Peer reviewed

Processing of Procorticotropin-Releasing Hormone (Pro-CRH): Molecular Forms of CRH in Normal and Preeclamptic Pregnancy

I Ahmed, B. P Glynn, A. V Perkins, M. G Castro, J Rowe, E Morrison and E. A Linton

The Journal of Clinical Endocrinology and Metabolism, Vol.85(2), pp.755-764

2000

DOI: https://doi.org/10.1210/jcem.85.2.6351

PMID: 10690887

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Abstract

This study examined the different molecular forms of CRH in normal and preeclampsia maternal plasma and protease-blocked placental extracts using antibodies to different regions of the CRH precursor, pro-CRH. In the absence of protease inhibitors, chromatographed normal placental extracts contained four peaks of immunoreactivity corresponding to unprocessed approximately 19-kDa pro-CRH, its approximately 8-kDa intermediate metabolite, pro-CRH125–194, its approximately 2.8-kDa midportion fragment, pro-CRH125–151, and 4.75-kDa CRH1–41. However, if protease inhibitors were included in the extraction medium, only pro-CRH and pro-CRH125–194 were found. Pro-CRH processing was more extensive in protease-blocked preeclampsia placentas than in those from normal pregnancy, with three peaks corresponding to pro-CRH, pro-CRH125–194, and mature CRH1–41 peptide found. Using quantitative competitive PCR, the messenger ribonucleic acid levels of CRH precursor in preeclampsia placentas were 1.7-fold higher than those in normal placentas (37.83 ± 3.48 vs. 21.83 ± 2.59 attomoles/μg total ribonucleic acid, respectively; P < 0.005). Preeclampsia placentas contained significantly more CRH1–41 cross-reactivity (4.72 ± 1.22 pmol/g) than normal term placentas (1.52 ± 0.39 pmol/g; P < 0.048) extracted in medium containing protease inhibitors. The content of pro-CRH125–151-reactive species in these extracts followed the same pattern, with more immunoreactivity detected in preeclampsia placentas (4.23 ± 1.39 pmol/g) than in those from normal term pregnancies (1.44 ± 0.32 pmol/g; P < 0.01). Sequential plasma samples from 10 women with normal pregnancy and 5 women with preeclampsia were assayed for pro-CRH125–151- and CRH1–41-immunoreactive species. In normal pregnancy, maternal plasma CRH1–41 immunoreactivity rose with increasing gestational age, reaching 460 ± 48 pmol/L at term. In women with preeclampsia, CRH1–41 levels at each gestational age point were higher than those at the equivalent stage of normal pregnancy. In contrast, the levels of pro-CRH125–151-immunoreactive species remained barely detectable throughout normal and preeclamptic pregnancy. Both pro-CRH and CRH1–41, but not pro-CRH125–151, were shown to bind to the plasma CRH-binding protein. Our findings highlight the importance of protection of placental tissue from degrading enzymes during extraction and show that most of the CRH in the human placenta exists as unprocessed pro-CRH, with very little in the form of CRH1–41 except in preeclampsia. Our studies using maternal plasma indicate that CRH1–41 is the only one of the pro-CRH fragments studied to be maintained in significant amounts in the maternal circulation and also the only fragment studied for which a specific plasma binding protein exists.

Details

Title: Processing of Procorticotropin-Releasing Hormone (Pro-CRH): Molecular Forms of CRH in Normal and Preeclamptic Pregnancy
Authors: I Ahmed (Author) - University of Oxford
B. P Glynn (Author) - University of Oxford
A. V Perkins (Author) - University of Oxford
M. G Castro (Author) - University of Manchester
J Rowe (Author) - University of Manchester
E Morrison (Author) - University of Manchester
E. A Linton (Corresponding Author) - University of Oxford
Publication details: The Journal of Clinical Endocrinology and Metabolism, Vol.85(2), pp.755-764
Publisher: Oxford University Press
DOI: 10.1210/jcem.85.2.6351
ISSN: 1945-7197
PMID: 10690887
Organisation Unit: School of Health and Behavioural Sciences - Legacy; School of Health
Language: English
Record Identifier: 99685295502621
Output Type: Journal article

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Collaboration types: Domestic collaboration
Web Of Science research areas: Endocrinology & Metabolism

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