Oral Presentation ESA-SRB-APEG-NZSE 2022

Regulation and function of SPINT1 in human placental trophoblasts  (#183)

Ciara N Murphy 1 , Natalie J Hannan 1 , David Simmons 2 , Tuong-Vi Nguyen 1 , Ping Cannon 1 , Manju Kandel 1 , Stephen Tong 1 , Tu'uhevaha J Kaitu'u-Lino 1
  1. Obstetrics & Gynaecology, Mercy Hospital for Women, University of Melbourne, Heidelberg, VIC, Australia
  2. School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia

 

Serine Peptidase Inhibitor Type 1 (SPINT1) is expressed by placental trophoblasts and its ablation in mice leads to compromised placental development and consequently embryonic lethality1,2. In humans, placental and circulating SPINT1 levels are reduced in fetal growth restriction (FGR), a complication mediated by placental insufficiency3. 

The aim of this work was to assess the regulation and function of SPINT1 in human placental cells using a first-trimester human trophoblast stem cell (hTSC) line. Placental insufficiency and FGR is associated with placental hypoxia, which we have previously found to cause reduced SPINT1 in isolated term cytotrophoblasts. Here, we tested whether this was also the case in hTSCs. Indeed, hypoxia (1% Oxygen) significantly reduced SPINT1 mRNA expression by 40% (p<0.01) and secretion by 50% (p<0.01) relative to normoxia (8% Oxygen).  

We next assessed whether SPINT1 is released from the surface of placental cells by matrix metalloproteinases (MMPs). We treated hTSCs with batimastat, an MMP inhibitor and found SPINT1 secretion into culture media was significantly reduced at a dose of 10uM batimastat by 28%, relative to control (p=0.0165). This suggests that while MMPs may contribute to SPINT1 release, there may also be alternate proteases that contribute. 

SPINT1 inhibits the degradative activity of several cell surface proteases, including matriptase and prostasin. We next assessed whether silencing SPINT1 (siRNA) in hTSCs would significantly alter protease activity by utilising a substrate which fluoresces when cleaved by matriptase or prostasin. We observed a non-significant increase in matriptase activity accompanies loss of SPINT1.  

We’ve shown placental SPINT1 is reduced by hypoxia and MMPs may contribute to its release from the placenta. We also confirm a likely role for SPINT1 in impairing matriptase/prostasin activity in human placental cells. Further studies are currently underway to ascertain the molecular regulators of SPINT1 and its potential role in cellular proliferation and differentiation.

  1. Szabo R, Molinolo A, List K, Bugge TH. Matriptase inhibition by hepatocyte growth factor activator inhibitor-1 is essential for placental development. Oncogene. 2007;26(11):1546-56.
  2. Tanaka H, Nagaike K, Takeda N, Itoh H, Kohama K, Fukushima T, et al. Hepatocyte growth factor activator inhibitor type 1 (HAI-1) is required for branching morphogenesis in the chorioallantoic placenta. Mol Cell Biol. 2005;25(13):5687-98.
  3. Kaitu'u-Lino TJ, MacDonald TM, Cannon P, Nguyen TV, Hiscock RJ, Haan N, et al. Circulating SPINT1 is a biomarker of pregnancies with poor placental function and fetal growth restriction. Nat Commun. 2020;11(1):2411.