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Activation of the AT1R/HIF-1 α /ACE axis mediates angiotensin II-induced VEGF synthesis in mesenchymal stem cells.

Liu C, Zhang JW, Hu L, Song YC, Zhou L, Fan Y, Zhu HY, Wang Y, Li QP - Biomed Res Int (2014)

Bottom Line: We have previously reported that angiotensin II (Ang II) pretreatment can significantly increase vascular endothelial growth factor (VEGF) synthesis in MSCs through the ERK1/2 and Akt pathways via the Ang II receptor type 1 (AT1R).The upregulation of ACE appeared after the rapid degradation of exogenous Ang II, and led to the formation of endogenous Ang II.We conclude that Ang II pretreatment, as a trigger, activated the AT1R/HIF-1α/ACE axis that then mediated Ang II-induced VEGF synthesis in MSCs.

View Article: PubMed Central - PubMed

Affiliation: Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Department of Pharmacology, Nanjing Medical University, Nanjing 210029, China.

ABSTRACT
A local renin-angiotensin system (RAS) is expressed in mesenchymal stem cells (MSCs) and regulates stem cell function. The local RAS influences the survival and tissue repairing ability of transplanted stem cells. We have previously reported that angiotensin II (Ang II) pretreatment can significantly increase vascular endothelial growth factor (VEGF) synthesis in MSCs through the ERK1/2 and Akt pathways via the Ang II receptor type 1 (AT1R). However, the role of angiotensin-converting enzyme (ACE) has not been clarified. Furthermore, whether Ang II pretreatment activates hypoxia-inducible factor-1α (HIF-1α) in MSCs has not been elucidated. Our data show that both ACE and HIF-1α are involved in promoting VEGF expression in MSCs, and that both are upregulated by Ang II stimulation. The upregulation of ACE appeared after the rapid degradation of exogenous Ang II, and led to the formation of endogenous Ang II. On the other hand, the ACE inhibitor, captopril, attenuated Ang II-enhanced HIF-1α upregulation, while HIF-1α suppression markedly attenuated ACE expression. This interesting finding suggests an interaction between ACE and HIF-1α. We conclude that Ang II pretreatment, as a trigger, activated the AT1R/HIF-1α/ACE axis that then mediated Ang II-induced VEGF synthesis in MSCs.

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Upregulation of ACE after Ang II-induced VEGF synthesis. (a) Western blot analysis of ACE. MSCs were exposed to Ang II (100 nM) for 6 h, 12 h, or 24 h. n = 5, **P < 0.01. (b) Determination of ACE activity. MSCs were exposed to Ang II (100 nM) for 1 h, 6 h, 12 h, 18 h, or 24 h. n = 5, *P < 0.05 every other group versus control. (c) Real-time qPCR examination of ACE mRNA levels. MSCs were exposed to Ang II (100 nM) for 12 h. n = 5, **P < 0.01. (d) Real-time qPCR analysis of VEGF mRNA level, **P < 0.01. (e) ELISA of VEGF secretion. MSCs were pretreated with or without captopril (1 μM for 1 h) before exposure to Ang II (100 nM) for 12 h. n = 5, *P < 0.05.
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fig1: Upregulation of ACE after Ang II-induced VEGF synthesis. (a) Western blot analysis of ACE. MSCs were exposed to Ang II (100 nM) for 6 h, 12 h, or 24 h. n = 5, **P < 0.01. (b) Determination of ACE activity. MSCs were exposed to Ang II (100 nM) for 1 h, 6 h, 12 h, 18 h, or 24 h. n = 5, *P < 0.05 every other group versus control. (c) Real-time qPCR examination of ACE mRNA levels. MSCs were exposed to Ang II (100 nM) for 12 h. n = 5, **P < 0.01. (d) Real-time qPCR analysis of VEGF mRNA level, **P < 0.01. (e) ELISA of VEGF secretion. MSCs were pretreated with or without captopril (1 μM for 1 h) before exposure to Ang II (100 nM) for 12 h. n = 5, *P < 0.05.

Mentions: To determine the influence of Ang II stimulation on ACE, we examined ACE mRNA and protein expression. After exposure to 100 nM Ang II, ACE protein expression in MSCs doubled within 24 h in a time-dependent manner (P < 0.01; Figure 1(a)). Real-time qPCR showed that the ACE mRNA level in pretreated MSCs increased to over 1.5-fold of control (P < 0.01; Figure 1(c)). Additionally, Ang II stimulation induced 1.7-fold increase in ACE activity (P < 0.05; Figure 1(b)). To ascertain whether ACE was involved in Ang II-induced VEGF synthesis, MSCs were preincubated with 1 μM captopril, a specific inhibitor of ACE, for 1 h before treatment with 100 nM Ang II for 12 h. VEGF mRNA expression and VEGF synthesis were then measured. After Ang II stimulation VEGF mRNA expression doubled. This effect was abolished by captopril (P < 0.01; Figure 1(d)). The Ang II-induced increase of VEGF secretion was also diminished in the captopril preincubation group (P < 0.05; Figure 1(e)). Therefore, we conclude that ACE promotes Ang II-induced VEGF expression in MSCs.


Activation of the AT1R/HIF-1 α /ACE axis mediates angiotensin II-induced VEGF synthesis in mesenchymal stem cells.

Liu C, Zhang JW, Hu L, Song YC, Zhou L, Fan Y, Zhu HY, Wang Y, Li QP - Biomed Res Int (2014)

Upregulation of ACE after Ang II-induced VEGF synthesis. (a) Western blot analysis of ACE. MSCs were exposed to Ang II (100 nM) for 6 h, 12 h, or 24 h. n = 5, **P < 0.01. (b) Determination of ACE activity. MSCs were exposed to Ang II (100 nM) for 1 h, 6 h, 12 h, 18 h, or 24 h. n = 5, *P < 0.05 every other group versus control. (c) Real-time qPCR examination of ACE mRNA levels. MSCs were exposed to Ang II (100 nM) for 12 h. n = 5, **P < 0.01. (d) Real-time qPCR analysis of VEGF mRNA level, **P < 0.01. (e) ELISA of VEGF secretion. MSCs were pretreated with or without captopril (1 μM for 1 h) before exposure to Ang II (100 nM) for 12 h. n = 5, *P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4221905&req=5

fig1: Upregulation of ACE after Ang II-induced VEGF synthesis. (a) Western blot analysis of ACE. MSCs were exposed to Ang II (100 nM) for 6 h, 12 h, or 24 h. n = 5, **P < 0.01. (b) Determination of ACE activity. MSCs were exposed to Ang II (100 nM) for 1 h, 6 h, 12 h, 18 h, or 24 h. n = 5, *P < 0.05 every other group versus control. (c) Real-time qPCR examination of ACE mRNA levels. MSCs were exposed to Ang II (100 nM) for 12 h. n = 5, **P < 0.01. (d) Real-time qPCR analysis of VEGF mRNA level, **P < 0.01. (e) ELISA of VEGF secretion. MSCs were pretreated with or without captopril (1 μM for 1 h) before exposure to Ang II (100 nM) for 12 h. n = 5, *P < 0.05.
Mentions: To determine the influence of Ang II stimulation on ACE, we examined ACE mRNA and protein expression. After exposure to 100 nM Ang II, ACE protein expression in MSCs doubled within 24 h in a time-dependent manner (P < 0.01; Figure 1(a)). Real-time qPCR showed that the ACE mRNA level in pretreated MSCs increased to over 1.5-fold of control (P < 0.01; Figure 1(c)). Additionally, Ang II stimulation induced 1.7-fold increase in ACE activity (P < 0.05; Figure 1(b)). To ascertain whether ACE was involved in Ang II-induced VEGF synthesis, MSCs were preincubated with 1 μM captopril, a specific inhibitor of ACE, for 1 h before treatment with 100 nM Ang II for 12 h. VEGF mRNA expression and VEGF synthesis were then measured. After Ang II stimulation VEGF mRNA expression doubled. This effect was abolished by captopril (P < 0.01; Figure 1(d)). The Ang II-induced increase of VEGF secretion was also diminished in the captopril preincubation group (P < 0.05; Figure 1(e)). Therefore, we conclude that ACE promotes Ang II-induced VEGF expression in MSCs.

Bottom Line: We have previously reported that angiotensin II (Ang II) pretreatment can significantly increase vascular endothelial growth factor (VEGF) synthesis in MSCs through the ERK1/2 and Akt pathways via the Ang II receptor type 1 (AT1R).The upregulation of ACE appeared after the rapid degradation of exogenous Ang II, and led to the formation of endogenous Ang II.We conclude that Ang II pretreatment, as a trigger, activated the AT1R/HIF-1α/ACE axis that then mediated Ang II-induced VEGF synthesis in MSCs.

View Article: PubMed Central - PubMed

Affiliation: Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Department of Pharmacology, Nanjing Medical University, Nanjing 210029, China.

ABSTRACT
A local renin-angiotensin system (RAS) is expressed in mesenchymal stem cells (MSCs) and regulates stem cell function. The local RAS influences the survival and tissue repairing ability of transplanted stem cells. We have previously reported that angiotensin II (Ang II) pretreatment can significantly increase vascular endothelial growth factor (VEGF) synthesis in MSCs through the ERK1/2 and Akt pathways via the Ang II receptor type 1 (AT1R). However, the role of angiotensin-converting enzyme (ACE) has not been clarified. Furthermore, whether Ang II pretreatment activates hypoxia-inducible factor-1α (HIF-1α) in MSCs has not been elucidated. Our data show that both ACE and HIF-1α are involved in promoting VEGF expression in MSCs, and that both are upregulated by Ang II stimulation. The upregulation of ACE appeared after the rapid degradation of exogenous Ang II, and led to the formation of endogenous Ang II. On the other hand, the ACE inhibitor, captopril, attenuated Ang II-enhanced HIF-1α upregulation, while HIF-1α suppression markedly attenuated ACE expression. This interesting finding suggests an interaction between ACE and HIF-1α. We conclude that Ang II pretreatment, as a trigger, activated the AT1R/HIF-1α/ACE axis that then mediated Ang II-induced VEGF synthesis in MSCs.

Show MeSH
Related in: MedlinePlus