Loss of heme oxygenase-1 accelerates mesodermal gene expressions during embryoid body development from mouse embryonic stem cells

Abstract

Heme oxygenase (HO)-1 is an inducible stress response protein and well known to protect cells and tissues against injury. Despite its important function in cytoprotection against physiological stress, the role of HO-1 in embryonic stem cell (ESC) differentiation remains largely unknown. We showed previously that induced pluripotent stem (iPS) cells that lack HO-1 are more sensitive to oxidant stress-induced cell death and more prone to lose pluripotent markers upon LIF withdrawal. To elucidate the role of HO-1 in ESC differentiation and to rule out the controversy of potential gene flaws in iPS cells, we derived and established mouse HO-1 knockout ESC lines from HO-1 knockout blastocysts. Using wild type D3 and HO-1 knockout ESCs in the 3-dimensional embryoid body (EB) differentiation model, we showed that at an early time point during EB development, an absence of HO-1 led to enhanced ROS level, concomitant with increased expressions of master mesodermal regulator brachyury and endodermal marker GATA6. In addition, critical smooth muscle cell (SMC) transcription factor serum response factor and its coactivator myocardin were enhanced. Furthermore, HO-1 deficiency increased Smad2 in ESCs and EBs, revealing a role of HO-1 in controlling Smad2 level. Smad2 not only mediates mesendoderm differentiation of mouse ESCs but also SMC development. Collectively, loss of HO-1 resulted in higher level of mesodermal and SMC regulators, leading to accelerated and enhanced SMC marker SM α-actin expression. Our results reveal a previously unrecognized function of HO-1 in regulating SMC gene expressions during ESC-EB development. More importantly, our findings may provide a novel strategy in enhancing ESC differentiation toward SMC lineage.

Novel Interplay between p53 and HO-1 in Embryonic Stem Cells

“…Based on the evidence that HO-1 is involved in stem cells differentiation [ 37 , 58 , 59 , 60 ], we analyzed the HO-1 expression in ES cells during this process. First, we exploited ChIP Atlas data-mining platform [ 61 ] to investigate histone modifications and the binding of multiple transcriptional regulators to Hmox1 locus in undifferentiated ES cells and in ES cells subjected to differentiation protocols.…”

“…In addition, during ES cells differentiation both HO-1 [ 37 , 58 , 60 , 82 , 83 , 84 ] and p53 [ 24 , 76 , 82 , 85 ] play a relevant role. Using the Chip Atlas platform, we found that in undifferentiated ES cells Hmox1 is associated with negative transcriptional regulators.…”

The pluripotency transcription factor OCT4 represses heme oxygenase‐1 gene expression

“…Additionally, enhanced HO-1 activity inhibits the differentiation of murine muscle precursors [61]. On the other hand, ES cells that do not express HO-1 show higher levels of mesodermal and smooth muscle cell markers during embryoid-body differentiation, suggesting that HO-1 could be regulating the expression of specific genes [22]. Moreover, HO-1 activity contributes to the differentiation and maturation of ES cells into cardiomyocytes [23] and HO-1 knockout PS cells show impaired differentiation toward cardiac lineage [24].…”

“…It was found that HO‐1 influences cell differentiation both positively and negatively, depending on the cell type [21]. Particularly, HO‐1 has been reported to upregulate a mesodermal gene expression profile during ES cell differentiation through embryoid‐body formation [22] and was also found to be involved in differentiation of ES cells into functional cardiac cells [23]. In line with these observations, it has been reported that knockout PS cells for Hmox1 displayed attenuated spontaneous cardiac differentiation.…”

The Emerging Roles of the Gaseous Signaling Molecules NO, H2S, and CO in the Regulation of Stem Cells

“…HO-1/CO has been shown to downregulate the pluripotency markers Sox2 and Oct4 and may enhance mitochondrial biogenesis and promote ESC differentiation and maturation into functional cardiomyocytes . In a three-dimensional embryoid body (EB) differentiation model, Lai et al used mouse HO-1 knockout ESC lines from HO-1 knockout blastocysts to elucidate the role of HO-1 in ESC differentiation . They showed that the absence of HO-1 led to increased expression of the master mesodermal regulator brachyury and the endodermal marker GATA6.…”