Augmented Expression of Piezo1 in the Uterine Vasculature During Pregnancy

Abstract

The maternal uterine circulation undergoes expansive remodeling during gestation to facilitate the many‐fold increase in uteroplacental blood flow required for normal pregnancy outcome. Although we and others have shown that endothelial nitric oxide (NO) is a key mediator of this process, the primary molecular sensor responsible for detecting shear stress and transducing it to eNOS activation has yet to be identified. The recent discovery of Piezo1 ‐ a large, mechanically‐activated cation channel that has been implicated in mechanosensing of shear stress in various cell types, including the endothelium, inspired this study. Notably, transfection of Piezo1 into HEK293 cells, which normally cannot sense shear stress, conferred a shear stress responsiveness evidenced by increased cytosolic calcium and eNOS activation. We hypothesized that Piezo1 may be present in uterine arteries, and that its expression would be augmented during pregnancy and linked to increased eNOS.Main uterine arteries (MUA) were collected from adult (12–14 week old) late pregnant (LP: gestational day 20, n=4) Sprague‐Dawley rats, and from age‐matched nonpregnant (NP, n=4) controls. Following euthanization, MUAs were dissected free of surrounding connective and adipose tissues, and cut open to remove any blood present in the lumen. Segments of MUA were either fixed and permeabilized for immunohistochemistry (IHC), or homogenized for Western Blotting (WB). Tissues were incubated with rabbit polyclonal Piezo1 antibody (Ab), eNOS Ab, β‐tubulin Ab; goat anti‐rabbit IgG‐HRP Ab (and/or Alexa Fluor® 488 Ab). Immunolabeled vessels were imaged using a Zeiss LSM 510 META confocal microscope @ 100x; for WB, proteins were detected with chemiluminescent substrate and analyzed using ImageJ software.Results(1) Piezo1 was detected in the MUA of both NP and LP rats (using either method), and localized to the arterial endothelium (IHC). (2) Both Piezo1 and eNOS expression were augmented in MUAs from LP vs. NP rats. Based on this preliminary information, we suggest that Piezo1 may play a role in transducing shear stress into the activation of eNOS in the uterine circulation during pregnancy, and thereby contributes to the expansive arterial remodeling required to maintain sufficient uteroplacental perfusion. This is the first study to identify this channel in uterine vessels, and to show a gestational effect on its expression. As both shear stress and uterine arterial remodeling are attenuated in preeclampsia (a serious gestational disease that afflicts ten million pregnant women worldwide each year), understanding the underlying mechanosensing/transducing mechanisms may lead to new therapeutic strategies for augmenting uteroplacental blood flow.Support or Funding InformationNIH R21 HD080156