scholarly journals Ca2+ Mediates HIF-dependent Upregulation of Aquaporin 1 in Pulmonary Arterial Smooth Muscle Cells

2021 ◽  
Author(s):  
Xin Yun ◽  
Haiyang Jiang ◽  
Gregg L. Semenza ◽  
Larissa A. Shimoda
Keyword(s):  
Transcriptional Regulation ◽  
Smooth Muscle ◽  
Water Channel ◽  
Cell Types ◽  
Pulmonary Vasculature ◽  
Arterial Smooth Muscle ◽  
Aquaporin 1 ◽  
Pulmonary Arterial ◽  
Pulmonary Arterial Smooth Muscle ◽  
Transcriptional Target

ABSTRACTProlonged exposure to hypoxia causes structural remodeling and sustained contraction of the pulmonary vasculature, resulting in the development of pulmonary hypertension. Both pulmonary arterial smooth muscle cell (PASMC) proliferation and migration contribute to the vascular remodeling. We previously showed that the protein expression of aquaporin 1 (AQP1), a membrane water channel protein, is elevated in PASMCs during following in vivo or in vitro exposure to hypoxia. Studies in other cell types suggest that AQP1 is a direct transcriptional target of hypoxia inducible factor (HIF)-1. Moreover, we and others have shown that an increase in intracellular calcium concentration ([Ca2+]i) is a hallmark of hypoxic exposure in PASMCs. Thus, we wanted to determine whether HIF regulates AQP1 in PASMCs and, if so, whether the process occurred via transcriptional regulation or was Ca2+-dependent. PASMCs were exposed to hypoxia, incubated with DMOG, which inhibits HIFα protein degradation or infected with constitutively active forms of HIF-1α or HIF-2α. Hypoxia, DMOG and HIF1/2α produced a time-dependent increase in AQP1 protein, but not mRNA. Interestingly, incubation with increasing HIF1/2α levels and DMOG increased [Ca2+]i in PASMCs, and this elevation was prevented by the voltage-gated Ca2+ channel inhibitor, verapamil (VER) and nonselective cation channel inhibitor SKF96365 (SKF). VER and SKF also blocked upregulation of AQP1 protein by DMOG or HIF1/2α, but had no effect on expression of GLUT1, a canonical HIF transcriptional target. Silencing of AQP1 abrogated increases in PASMC migration and proliferation induced by HIF1/2α, suggesting induction of AQP1 protein by HIF1/2α has a functional outcome in these cells. Thus, our results show that contrary to reports in other cell types, in PASMCs, AQP1 does not appear to be a direct target for HIF transcriptional regulation. Instead, AQP1 protein may be upregulated by a mechanism involving HIF-dependent increases in [Ca2+]i.

scholarly journals Hypoxia-induced migration in pulmonary arterial smooth muscle cells requires calcium-dependent upregulation of aquaporin 1

2012 ◽  
Vol 303 (4) ◽  
pp. L343-L353 ◽  
Author(s):  
Kyle Leggett ◽  
Julie Maylor ◽  
Clark Undem ◽  
Ning Lai ◽  
Wenju Lu ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Arterial Smooth Muscle ◽  
Aquaporin 1 ◽  
Protein Levels ◽  
Pulmonary Arterial ◽  
Pulmonary Arterial Smooth Muscle ◽  
And Migration

Pulmonary arterial smooth muscle cell (PASMC) migration is a key component of the vascular remodeling that occurs during the development of hypoxic pulmonary hypertension, although the mechanisms governing this phenomenon remain poorly understood. Aquaporin-1 (AQP1), an integral membrane water channel protein, has recently been shown to aid in migration of endothelial cells. Since AQP1 is expressed in certain types of vascular smooth muscle, we hypothesized that AQP1 would be expressed in PASMCs and would be required for migration in response to hypoxia. Using PCR and immunoblot techniques, we determined the expression of AQPs in pulmonary vascular smooth muscle and the effect of hypoxia on AQP levels, and we examined the role of AQP1 in hypoxia-induced migration in rat PASMCs using Transwell filter assays. Moreover, since the cytoplasmic tail of AQP1 contains a putative calcium binding site and an increase in intracellular calcium concentration ([Ca2+]i) is a hallmark of hypoxic exposure in PASMCs, we also determined whether the responses were Ca2+ dependent. Results were compared with those obtained in aortic smooth muscle cells (AoSMCs). We found that although AQP1 was abundant in both PASMCs and AoSMCs, hypoxia selectively increased AQP1 protein levels, [Ca2+]i, and migration in PASMCs. Blockade of Ca2+ entry through voltage-dependent Ca2+ or nonselective cation channels prevented the hypoxia-induced increase in PASMC [Ca2+]i, AQP1 levels, and migration. Silencing AQP1 via siRNA also prevented hypoxia-induced migration of PASMCs. Our results suggest that hypoxia induces a PASMC-specific increase in [Ca2+]i that results in increased AQP1 protein levels and cell migration.

scholarly journals Aquaporin 1-mediated changes in pulmonary arterial smooth muscle cell migration and proliferation involve β-catenin

2017 ◽  
Vol 313 (5) ◽  
pp. L889-L898 ◽  
Author(s):  
Xin Yun ◽  
Haiyang Jiang ◽  
Ning Lai ◽  
Jian Wang ◽  
Larissa A. Shimoda
Keyword(s):  
Smooth Muscle ◽  
Cell Migration ◽  
Cyclin D1 ◽  
Dual Function ◽  
Arterial Smooth Muscle ◽  
Aquaporin 1 ◽  
Protein Levels ◽  
Pulmonary Arterial ◽  
Pulmonary Arterial Smooth Muscle ◽  
Cell Migration And Proliferation

Exposure to hypoxia induces migration and proliferation of pulmonary arterial smooth muscle cells (PASMCs), leading to vascular remodeling and contributing to the development of hypoxic pulmonary hypertension. The mechanisms controlling PASMC growth and motility are incompletely understood, although aquaporin 1 (AQP1) plays an important role. In tumor, kidney, and stem cells, AQP1 has been shown to interact with β-catenin, a dual function protein that activates the transcription of crucial target genes (i.e., c-Myc and cyclin D1) related to cell migration and proliferation. Thus the goal of this study was to examine mechanisms by which AQP1 mediates PASMC migration and proliferation, with a focus on β-catenin. Using primary rat PASMCs from resistance level pulmonary arteries infected with adenoviral constructs containing green fluorescent protein (control; AdGFP), wild-type AQP1 (AdAQP1), or AQP1 with the COOH-terminal tail deleted (AdAQP1M), we demonstrated that increasing AQP1 expression upregulated β-catenin protein levels and the expression (mRNA and protein) of the known β-catenin targets c-Myc and cyclin D1. In contrast, infection with AdAQP1M had no effect on any of these variables. Using silencing approaches to reduce β-catenin levels prevented both hypoxia- and AQP1-induced migration and proliferation of PASMCs, as well as induction of c-Myc and cyclin D1 by AQP1. Thus our results indicate that elevated AQP1 levels upregulate β-catenin protein levels, via a mechanism requiring the AQP1 COOH-terminal tail, enhancing expression of β-catenin targets and promoting PASMC proliferation and migration.

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