Proteomic identification of membrane-associated placental protein 4 (MP4) as perlecan and characterization of its placental expression in normal and pathologic pregnancies

Nikolett Lilla Szenasi; Eszter Toth; Andrea Balogh; Kata Juhasz; Katalin Karaszi; Oliver Ozohanics; Zsolt Gelencser; Peter Kiraly; Beata Hargitai; Laszlo Drahos; Petronella Hupuczi; Ilona Kovalszky; Zoltan Papp; Nandor Gabor Than

doi:10.7717/peerj.6982

Proteomic identification of membrane-associated placental protein 4 (MP4) as perlecan and characterization of its placental expression in normal and pathologic pregnancies

PeerJ. 2019 Jun 20:7:e6982. doi: 10.7717/peerj.6982. eCollection 2019.

Authors

Nikolett Lilla Szenasi^#¹, Eszter Toth^#^{1

2}, Andrea Balogh¹, Kata Juhasz¹, Katalin Karaszi^{1

3}, Oliver Ozohanics^{2

4}, Zsolt Gelencser¹, Peter Kiraly¹, Beata Hargitai⁵, Laszlo Drahos², Petronella Hupuczi⁶, Ilona Kovalszky³, Zoltan Papp^{6

7}, Nandor Gabor Than^{1

3

6}

Affiliations

¹ Systems Biology of Reproduction Research Group, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
² MS Proteomics Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.
³ First Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary.
⁴ Department of Medical Biochemistry, Faculty of Medicine, Semmelweis University, Budapest, Hungary.
⁵ West Midlands Perinatal Pathology, Birmingham Women's Hospital, Birmingham, UK.
⁶ Maternity Private Clinic of Obstetrics and Gynecology, Budapest, Hungary.
⁷ Department of Obstetrics and Gynecology, Semmelweis University, Budapest, Hungary.

^# Contributed equally.

Abstract

Background: More than 50 human placental proteins were isolated and physico-chemically characterized in the 70-80s by Hans Bohn and co-workers. Many of these proteins turned to have important role in placental functions and diagnostic significance in pregnancy complications. Among these proteins was membrane-associated placental protein 4 (MP4), for which identity or function has not been identified yet. Our aim was to analyze the sequence and placental expression of this protein in normal and complicated pregnancies including miscarriage, preeclampsia and HELLP syndrome.

Methods: Lyophilized MP4 protein and frozen healthy placental tissue were analyzed using HPLC-MS/MS. Placental tissue samples were obtained from women with elective termination of pregnancy (first trimester controls, n = 31), early pregnancy loss (EPL) (n = 13), early preeclampsia without HELLP syndrome (n = 7) and with HELLP syndrome (n = 8), late preeclampsia (n = 8), third trimester early controls (n = 5) and third trimester late controls (n = 9). Tissue microarrays were constructed from paraffin-embedded placentas (n = 81). Slides were immunostained with monoclonal perlecan antibody and evaluated using light microscopy and virtual microscopy. Perlecan was also analyzed for its expression in placentas from normal pregnancies using microarray data.

Results: Mass spectrometry-based proteomics of MP4 resulted in the identification of basement membrane-specific heparan sulfate proteoglycan core protein also known as perlecan. Immunohistochemistry showed cytoplasmic perlecan localization in syncytiotrophoblast and cytotrophoblasts of the villi. Perlecan immunoscore decreased with gestational age in the placenta. Perlecan immunoscores were higher in EPL compared to controls. Perlecan immunoscores were higher in early preeclampsia without and with HELLP syndrome and lower in late preeclampsia than in respective controls. Among patients with preeclampsia, placental perlecan expression positively correlated with maternal vascular malperfusion and negatively correlated with placental weight.

Conclusion: Our findings suggest that an increased placental perlecan expression may be associated with hypoxic ischaemic injury of the placenta in miscarriages and in early preeclampsia with or without HELLP syndrome.

Keywords: Miscarriage; Placenta; Preeclampsia; Pregnancy; Proteoglycan.

Grants and funding

This work was supported by grants from the Hungarian National Science Fund (OTKA-K124862 Grant), the Hungarian Academy of Sciences (Momentum LP2014-7/2014 Grant), the Hungarian National Research, Development and Innovation Fund (FIEK_16-1-2016-0005 Grant) and from the European Union (FP6 Pregenesys-037244 Grant). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.