Dataset Information

Period2 deficiency blunts hypoxia-induced mobilization and function of endothelial progenitor cells.

ABSTRACT:

Background

In the clinic, variations in circadian rhythm are evident in patients with cardiovascular disease, and the risk of cardiovascular events increases when rhythms are disrupted. In this study, we focused on the role of the circadian gene period2 (per2) in mobilization and function of endothelial progenitor cells (EPCs) in vitro and in vivo after myocardial infarction (MI) in mice.

Methods and results

MI was produced by surgical ligation of the left anterior descending coronary artery in mice with and without per2 deficiency. Trans-thoracic echocardiography was used to evaluate cardiac function in mice. Per2-/- mice with MI showed decreased cardiac function and increased infarct size. The number of CD34+ cells and capillary density were decreased in the myocardium of per2-/- mice on immunohistochemistry. Flow cytometry revealed decreased number of circulating EPCs in per2-/- mice after MI. In vitro, per2-/- EPCs showed decreased migration and tube formation capacity under hypoxia. Western blot analysis revealed inhibited activation of extracellular signal-regulated kinase and Akt signaling in the bone marrow of per2-/- mice and inhibited PI3K/Akt expression in per2-/- EPCs under hypoxia.

Conclusions

Per2 modulates EPC mobilization and function after MI, which is important to recovery after MI in mice.

SUBMITTER: Qin T

PROVIDER: S-EPMC4182576 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Publications

Period2 deficiency blunts hypoxia-induced mobilization and function of endothelial progenitor cells.

Qin Tao T Sun Yuan-Yuan YY Bai Wen-Wu WW Wang Bo B Xing Yi-Fan YF Liu Yan Y Yang Rui-Xue RX Zhao Yu-Xia YX Li Jian-Min JM

PloS one 20140930 9

<h4>Background</h4>In the clinic, variations in circadian rhythm are evident in patients with cardiovascular disease, and the risk of cardiovascular events increases when rhythms are disrupted. In this study, we focused on the role of the circadian gene period2 (per2) in mobilization and function of endothelial progenitor cells (EPCs) in vitro and in vivo after myocardial infarction (MI) in mice.<h4>Methods and results</h4>MI was produced by surgical ligation of the left anterior descending coro ...[more]

PMID: 25268972

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Project description:BackgroundExposure to ambient fine particulate matter air pollution (PM(2.5); < 2.5 µm in aerodynamic diameter) induces endothelial dysfunction and increases the risk for cardiovascular disease. Endothelial progenitor cells (EPCs) contribute to postnatal endothelial repair and regeneration. In humans and mice, EPC levels are decreased upon exposure to elevated levels of PM(2.5).ObjectiveWe examined the mechanism by which PM(2.5) exposure suppresses circulating levels of EPCs.MethodsMice were exposed to HEPA-filtered air or concentrated ambient fine particulate matter (CAP, 30-100 µg/m³) from downtown Louisville (Kentucky) air, and progenitor cells from peripheral blood or bone marrow were analyzed by flow cytometry or by culture ex vivo.ResultsExposure of the mice to CAP (6 hr/day) for 4-30 days progressively decreased circulating levels of EPCs positive for both Flk-1 and Sca-1 (Flk-1(+)/Sca-1(+)) without affecting stem cells positive for Sca-1 alone (Sca-1(+)). After 9 days of exposure, a 7-day exposure-free period led to complete recovery of the circulating levels of Flk-1(+)/Sca-1(+) cells. CAP exposure decreased circulating levels of EPCs independent of apoptosis while simultaneously increasing Flk-1(+)/Sca-1(+) cells in the bone marrow. We observed no change in tissue deposition of these cells. CAP exposure suppressed vascular endothelial growth factor (VEGF)-induced Akt and endothelial nitric oxide synthase (eNOS) phosphorylation in the aorta, and it prevented VEGF/AMD3100-induced mobilization of Flk-1(+)/Sca-1(+) cells into the peripheral blood. Treatment with stem cell factor/AMD3100 led to a greater increase in circulating Flk-1(+)/Sca-1(+) cells in CAP-exposed mice than in mice breathing filtered air.ConclusionExposure to PM(2.5) increases EPC levels in the bone marrow by preventing their mobilization to the peripheral blood via inhibition of signaling events triggered by VEGF-receptor stimulation that are upstream of c-kit activation. Suppression of EPC mobilization by PM(2.5) could induce deficits in vascular repair or regeneration.

Project description:BackgroundAdaptation to low oxygen by changing gene expression is vitally important for cell survival and tissue development. The sprouting of new blood vessels, initiated from endothelial cells, restores the oxygen supply of ischemic tissues. In contrast to the transcriptional response induced by hypoxia, which is mainly mediated by members of the HIF family, there are only few studies investigating alternative splicing events. Therefore, we performed an exon array for the genome-wide analysis of hypoxia-related changes of alternative splicing in endothelial cells.Methodology/principal findingsHuman umbilical vein endothelial cells (HUVECs) were incubated under hypoxic conditions (1% O(2)) for 48 h. Genome-wide transcript and exon expression levels were assessed using the Affymetrix GeneChip Human Exon 1.0 ST Array. We found altered expression of 294 genes after hypoxia treatment. Upregulated genes are highly enriched in glucose metabolism and angiogenesis related processes, whereas downregulated genes are mainly connected to cell cycle and DNA repair. Thus, gene expression patterns recapitulate known adaptations to low oxygen supply. Alternative splicing events, until now not related to hypoxia, are shown for nine genes: six which are implicated in angiogenesis-mediated cytoskeleton remodeling (cask, itsn1, larp6, sptan1, tpm1 and robo1); one, which is involved in the synthesis of membrane-anchors (pign) and two universal regulators of gene expression (cugbp1 and max).Conclusions/significanceFor the first time, this study investigates changes in splicing in the physiological response to hypoxia on a genome-wide scale. Nine alternative splicing events, until now not related to hypoxia, are reported, considerably expanding the information on splicing changes due to low oxygen supply. Therefore, this study provides further knowledge on hypoxia induced gene expression changes and presents new starting points to study the hypoxia adaptation of endothelial cells.

Dataset Information

Period2 deficiency blunts hypoxia-induced mobilization and function of endothelial progenitor cells.

Background

Methods and results

Conclusions

Publications

Period2 deficiency blunts hypoxia-induced mobilization and function of endothelial progenitor cells.

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