Arachidonic acid release by H₂O₂ mediated proliferation of mouse embryonic stem cells: Involvement of Ca²⁺/PKC and MAPKs‐induced EGFR transactivation

Abstract

Reactive oxygen species (ROS) generated by a variety of endogenous factors and roles in embryonic stem (ES) cells has yet to be identified. Thus, we examined role of arachidonic acid (AA) in H(2)O(2)-induced proliferation of mouse ES cells and its related signaling molecules. AA release was maximally increased in response to 10(-4) M H(2)O(2) for 1 h. In addition, H(2)O(2) increased intracellular Ca(2+) concentration ([Ca(2+)](i)) and the phosphorylation of protein kinase C (PKC), p44/42, p38 mitogen-activated protein kinase (MAPK), and JNK/SAPK. Moreover, H(2)O(2) induced an increase in the phosphorylation of epidermal growth factor receptor (EGFR), which was blocked by the inhibition of p44/42 or p38 MAPKs. The inhibition of each signal molecule with specific inhibitors blocked H(2)O(2)-induced cytosolic phospholipase A(2) (cPLA(2)) activation and AA release. H(2)O(2) increased NF-kappaB phosphorylation to induce an increase in the levels of cyclooxygenase (COX)-2 proteins. Subsequently, H(2)O(2) stimulated PGE(2) synthesis, which was reduced by the inhibition of NF-kappaB activation. Moreover, each H(2)O(2) or PGE(2) increased DNA synthesis and the number of cells. However, H(2)O(2)-induced increase in DNA synthesis was inhibited by the suppression of cPLA(2) pathway. In conclusion, H(2)O(2) increased AA release and PGE(2) production by the upregulation of cPLA(2) and COX-2 via Ca(2+)/PKC/MAPKs and EGFR transactivation, subsequently proliferation of mouse ES cells.

Proliferation and Pluripotency of Human Embryonic Stem Cells Maintained on Type I Collagen

“…PGE 2 was found to have a positive affect on the growth of hematopoietic stem cell progenitors obtained from zebrafish and mouse embryonic stem cells [84]. PTGS2 activity and PGE 2 have also been associated with mouse embryonic stem cell proliferation [85][86][87] and prevention of apoptosis [88]. These data are in agreement with our findings of increased PTGS2 activity and PGE 2 secretion in cells that are supportive of hESC growth.…”

Cytosolic phospholipase A2alpha amplifies early cyclooxygenase-2 expression, oxidative stress and MAP kinase phosphorylation after cerebral ischemia in mice

“…Our data demonstrate that cPLA 2 α enhances ROS formation by MCAO (Figure 7) while others have shown that oxidative stress in mouse embryonic stem cells causes MAPK dependent phosphorylation of cPLA 2 α [49]. This interaction has the potential to form a positive feedback loop in which cPLA 2 α-dependent ROS increase kinase activation which leads to further cPLA 2 α activation.…”

Enterococcus faecalis Enhances Cell Proliferation through Hydrogen Peroxide-Mediated Epidermal Growth Factor Receptor Activation

“…faecalis induces cell proliferation through hydrogen peroxide-mediated EGFR activation. Several studies indicate that exposure to oxidative stress, such as the presence of H 2 O 2 , preferentially facilitates EGFR activation (38,58,59), enhances cell proliferation (43,57,70), and thereby promotes tumorigenesis (29). Because E. faecalis can generate a considerable amount of oxidants, such as superoxide and H 2 O 2 (30), our next series of experiments was designed to determine whether H 2 O 2 production by E. faecalis VF could induce cell proliferation via EGFR activation.…”