Absence of Heme Oxygenase‐1 Accelerates Smooth Muscle Cell Gene Expressions during Embryoid Body Development from Mouse Embryonic Stem Cells

Abstract

Heme oxygenase (HO)‐1 is well known as a stress response protein, playing an important role for protecting cells and tissues from injury with its antioxidative and anti‐inflammatory properties. Although it possess crucial cytoprotective ability against physiological stress, the functions of HO‐1 in embryonic stem cell (ESC) differentiation remain to be elucidated. In previous study, we indicated that in the absence of HO‐1, induced pluripotent stem (iPS) cells are more sensitive to oxidant stress‐induced cell death and more prone to lose pluripotent markers without LIF. To investigate the role of HO‐1 in ESC differentiation and to eliminate the controversy of potential gene defects in iPS cells, we attempted to set up mouse HO‐1 knockout ESC lines from HO‐1 knockout blastocysts. Under the 3‐dimensional embryoid body (EB) formation from wild type D3 and HO‐1 knockout ESCs, we showed that at an early time point after EB differentiation, a lack of HO‐1 led to enhanced ROS level, accompanied with upregulations of master mesodermal regulator brachyury and endodermal marker GATA6. Furthermore, critical smooth muscle cell (SMC) transcription factor serum response factor and its coactivator myocardin were increased. Moreover, HO‐1 deficiency augmented Smad2 expression in ESCs and EBs, indicating that Smad2 not only mediates mesendoderm differentiation of mouse ESCs but also SMC development. Taken together, absence of HO‐1 contributed to higher level of mesodermal and SMC regulators, leading to accelerated and enhanced SMC marker expressions. Our results demonstrated a previously indeterminate function of HO‐1 in regulating SMC gene expressions during ESC‐EB development. More significantly, this finding may provide a novel approach to enhance SMC differentiation from ESCs.Support or Funding InformationNational Health Research Institutes and Central Government S&T grant, Taiwan (106‐0324‐01‐10‐07), Ministry of Science and Technology of Taiwan (MOST 104‐2320‐B‐400‐006‐MY3 and MOST 106‐3114‐Y‐043‐021), and National Health Research Institutes of Taiwan (CS‐106‐PP‐05).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.