RETRACTED ARTICLE: Ang II-AT2R increases mesenchymal stem cell migration by signaling through the FAK and RhoA/Cdc42 pathways in vitro

Abstract

BackgroundMesenchymal stem cells (MSCs) migrate via the bloodstream to sites of injury and are possibly attracted by inflammatory factors. As a proinflammatory mediator, angiotensin II (Ang II) reportedly enhances the migration of various cell types by signaling via the Ang II receptor in vitro. However, few studies have focused on the effects of Ang II on MSC migration and the underlying mechanisms.MethodsHuman bone marrow MSCs migration was measured using wound healing and Boyden chamber migration assays after treatments with different concentrations of Ang II, an AT1R antagonist (Losartan), and/or an AT2R antagonist (PD-123319). To exclude the effect of proliferation on MSC migration, we measured MSC proliferation after stimulation with the same concentration of Ang II. Additionally, we employed the focal adhesion kinase (FAK) inhibitor PF-573228, RhoA inhibitor C3 transferase, Rac1 inhibitor NSC23766, or Cdc42 inhibitor ML141 to investigate the role of cell adhesion proteins and the Rho-GTPase protein family (RhoA, Rac1, and Cdc42) in Ang II-mediated MSC migration. Cell adhesion proteins (FAK, Talin, and Vinculin) were detected by western blot analysis. The Rho-GTPase family protein activities were assessed by G-LISA and F-actin levels, which reflect actin cytoskeletal organization, were detected by using immunofluorescence.ResultsHuman bone marrow MSCs constitutively expressed AT1R and AT2R. Additionally, Ang II increased MSC migration in an AT2R-dependent manner. Notably, Ang II-enhanced migration was not mediated by Ang II-mediated cell proliferation. Interestingly, Ang II-enhanced migration was mediated by FAK activation, which was critical for the formation of focal contacts, as evidenced by increased Talin and Vinculin expression. Moreover, RhoA and Cdc42 were activated by FAK to increase cytoskeletal organization, thus promoting cell contraction. Furthermore, FAK, Talin, and Vinculin activation and F-actin reorganization in response to Ang II were prevented by PD-123319 but not Losartan, indicating that FAK activation and F-actin reorganization were downstream of AT2R.ConclusionsThese data indicate that Ang II-AT2R regulates human bone marrow MSC migration by signaling through the FAK and RhoA/Cdc42 pathways. This study provides insights into the mechanisms by which MSCs home to injury sites and will enable the rational design of targeted therapies to improve MSC engraftment.

A Preview of Selected Articles - October 2018

“…In a study published in STEM CELLS TRANSLA-TIONAL MEDICINE, Xu et al [8] utilized MSC genetically modified to overexpress angiotensin II type 2 receptors (AT2R) to increase their homing ability to damaged lung tissue in a model of acute lung injury. This study builds upon their previous findings that angiotensin II promotes MSC migration specifically through AT2R [9]. They found that mice injected with AT2R-MSC displayed increased homing and decreased inflammatory responses in the lungs compared with controls.…”

Genetic Modification of Mesenchymal Stem Cells Overexpressing Angiotensin II Type 2 Receptor Increases Cell Migration to Injured Lung in LPS-Induced Acute Lung Injury Mice

“…The mediators that promote inflammation might also be the same molecules that attract MSCs to the site of tissue injury. Furthermore, we have found that Ang II promote the migration of MSCs in vitro mainly by interaction with AT2R in our previous study [10]. However, the literature showed that chemokine receptors expression on MSCs decrease as cells are expanded in vitro [11], ultimately limiting their benefit in vivo.…”

“…Human bone marrow MSCs were purchased from Cyagen Biosciences Inc. (Guangzhou, China). The cells were identified by detecting cell surface phenotypes and their multipotent potential for differentiation along the adipogenic, osteogenic, and chondrogenic lineages and maintained as previously described . Cells were passaged every 3–4 days by 0.25% trypsin‐ethylenediaminetetraacetic acid (Gibco, Carlsbad, CA, USA) when they reached about 80% confluence and were used for the experimental protocols between passages 5 and 10 .…”

Elevated levels of the small GTPase Cdc42 induces senescence in male rat mesenchymal stem cells

“…This increased ROS production in ADMSCs from aged rats was attenuated by CASIN with no significant effects on CM-H2DCFDA intensity in younger cells. Impaired actin polymerization is another hallmark of cell senescence (Kasper et al 2009;Li et al 2017;Xu et al 2017), and it can be mediated by the upregulation and activation of Cdc42 (Tang and Gunst 2004;Zlotorynski 2015). We employed QIM of F-actin labeled with Actin-green TM 488 ReadyProbes TM cells to quantify actin polymerization in ADMSCs isolated from young and old animals.…”

“…In human adult-derived MSCs Cdc42 plays multiple regulatory roles, including in the processes of osteogenic and adipogenic differentiation (Gao et al 2011;Jirong Wang 2014;Shin et al 2014), and elevated Cdc42-GTP levels lead to MSC morphology changes and elevated Factin stress fibres that are features associated with cellular senescence (Xu et al 2017). In addition, an altered microenvironment causes an increased expression of Cdc42 in mouse MSCs that may lead to senescent-like changes (McGrail et al 2012), and with advancing adult age there is an increasing deficit of cellular proliferation and signal transduction control in MSCs that leads to adipogenic differentiation (Raggi and Berardi 2012).…”