Hypoxia‐induced ARHGAP26 deficiency inhibits the proliferation and migration of human ductus arteriosus smooth muscle cell through activating RhoA‐ROCK‐PTEN pathway

Abstract

The Rho family plays crucial roles in O 2 -induced vasoconstriction, cell proliferation, and migration. Rho GTPase-activating protein 26 (ARHGAP26) is a GTPase-activating protein for the small GTPases of the Rho family. Our previous studies have demonstrated that ARHGAP26 expression was significantly downregulated in patent human ductus arteriosus (DA) tissue. However, its role underlying the maintenance of DA patency is unclear. In this study, patent (fetal) and constricted (newborn) mouse DA tissues were harvested to confirm the differences in the levels of expression of ARHGAP26. Human DA smooth muscle cells (DASMCs) were isolated and cultured in vitro and used to test the function of ARHGAP26. The expression of ARHGAP26 was significantly lower in patent (fetal) than constricted (newborn) mouse DA. ARHGAP26-knocked-down human DASMCs showed reduced proliferation and migration, which are both crucial to anatomic closure of DA. Moreover, after culturing under hypoxic conditions, the expression of ARHGAP26 in human DASMCs was significantly lower and hypoxia-induced ARHGAP26 deficiency activated the phosphorylation level of phosphatase and tensin homolog (PTEN) in DASMCs by mediating the activity of RhoA and RhoA-associated kinase 1 (ROCK1). Use of Y27632, an inhibitor of ROCK which further reduces the phospholipid activity of PTEN can reverse the inhibitory effect of PTEN on the

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“…Within heterogeneous populations, the outgrowing tumor cells in primary tissues may suffer again from senescent stimulation under hypoxic conditions [225]. In line with such thought, senescence biomarkers such as FN reexpression and RhoA-mediated actin stress fiber cytoskeleton become apparent in tumor cells suffering from hypoxic stimulations [206,227,228]. Conceptually, tumor cells that have continuously evolved and harbored certain degree of genomic instability would not behave similarly to precancerous cells and stay in the senescent state where cells are stopped in the G0 phase but likely slower their cell cycle progression to avoid apoptosis and are prepared to switch to mesenchymal plasticity [202,216,217].…”

A novel role for PGE2-EP4 in the developmental programming of the mouse ductus arteriosus: consequences for vessel maturation and function

“…Because of the size of the mouse DA, disaggregation of cells from tissue, or studies of unpassaged primary cells could not yield the quantity of cells necessary for our studies. Although the loss of phenotype is a common consequence of culturing primary cells with FBS or for multiple passages ( 115 , 116 ), we tried to minimize these concerns by using low passage cells and serum starvation before experiments, similar to other DA SMC studies ( 33 , 62 – 64 , 117 , 118 ). We found migratory differences between cultured DA and Ao cells, suggesting that some degree of tissue-specific identity was maintained.…”