Up-regulation of GLP-1R improved the dysfunction of late EPCs under hyperglycemia by regulating SIRT1 expression.

The dysfunction of endothelial progenitor cells (EPCs) is closely associated with diabetic vascular complications. Both glucagonlike peptide-1 receptor (GLP-1R) and silent information regulator 1 (SIRT1) can control systemic glucose homeostasis and protect endothelial cells against hyperglycemia-induced oxidative stress. In this study, we mainly assessed the role played by SIRT1 and GLP-1R and their relationship in regulating the function of late EPCs under hyperglycemia stimulation. Human peripheral blood mononuclear cells (PBMCs) were cultured in EGM-2 medium and induced to differentiate into EPCs and 25 mM glucose was used to stimulate EPCs to obtain a hyperglycemia condition. Subsequently, the expression and location of GLP-1R and SIRT1 in EPCs were detected. After GLP-1R or SIRT1 knockdown, or the treatment by GLP-1R agonist and/or SIRT1 agonist/inhibitor, the effects of SIRT1 and GLP-1R and their relationship in regulating the function of late EPCs under hyperglycemia stimulation was studied by detecting the apoptosis, migration, adhesion and angiogenicity abilities of EPCs. Results demonstrated that, in high-glucose stimulated EPCs, the expression of GLP-1R and SIRT1 was down-regulated. The knockdown of either GLP-1R or SIRT1 could increase EPCs apoptosis and weaken the migration, adhesion and angiogenicity abilities of EPCs. In addition, the improvement effects of Exendin-4 or GLP-1R over-expression on EPCs dysfunction could be weakened to some degree under SIRT1 knockdown. In conclusion, both GLP-1R and SIRT1 expression played important roles in regulating EPCs dysfunction under hyperglycemia and the up-regulation of GLP-1R improved the dysfunction of late EPCs by regulating SIRT1 expression.

Shear stress improves the endothelial progenitor cell function via the CXCR7/ERK pathway axis in the coronary artery disease cases.

BACKGROUND: Dysfunction in the late Endothelial Progenitor Cells (EPCs) is responsible for endothelial repair in patients with Coronary Artery Disease (CAD), and the shear stress is beneficial for EPCs function. However, the impact of shear stress on the capacity of EPCs in CAD patients has not been elucidated yet. The C-X-C chemokine receptor 7/extracellular signal-regulated kinase (CXCR7)/(ERK) pathways are identified to regulate EPCs function in CAD patients. Here, we hypothesize that shear stress upregulates the CXCR7/ERK pathways, which restore the EPCs function in CAD patients. METHODS: The human Peripheral Blood Mononuclear Cells (PBMCs) were collected from healthy adults and CAD patients and then used for EPCs cultivation. The Lv-siRNA for human CXCR7 was transfected into induced EPCs isolated from the CAD patients. Meanwhile, the EPCs from CAD patients were subjected to shear stress generated by a biomimetic device. Next, the cell viability, migration, tube formation, and apoptosis were detected by CCK-8, Transwell assay, Matrigel, and flow cytometry, respectively. Also, the CXCR7/ERK pathways in human EPCs were analyzed by Western blotting and qRT-PCR. RESULT: Compared to the EPCs collected from normal adults, the CAD patient-derived EPCs showed reduced in vitro vasculogenic capacity. Also, the level of CXCR7 in CAD patient-derived EPCs was significantly reduced compared to the EPCs of healthy subjects. Meanwhile, the extracellular signal-regulated kinase (ERK), which represents a CXCR7 downstream signaling pathway, had decreased phosphorylation level. The shear stress treatment augmented the CXCR7 expression and also elevated ERK phosphorylation, which is comparable to the up-regulation of CAD patient-derived EPCs function. Further, the small interfering RNA (siRNA)-mediated CXCR7 knockdown diminished the enhanced migration, adhesion, and tube formation capacity of shear stress treated CAD patient-derived EPCs. CONCLUSION: Up-regulation of the CXCR7/ERK pathways by shear stress can be a promising new target in enhancing the vasculogenic ability of CAD patient-derived EPCs.

miR-155 functions downstream of angiotensin II receptor subtype 1 and calcineurin to regulate cardiac hypertrophy.

Cardiac hypertrophy is characterized by maladaptive tissue remodeling that may lead to heart failure or sudden death. MicroRNAs (miRs) are negative regulators of angiotensin II and the angiotensin II receptor subtype 1 (AGTR1), which are two components involved in cardiac hypertrophy. In the present study, the interaction between angiotensin II receptor subtype 1 (AGTR1) signaling and miR-155 was investigated. Rat H9C2 (2-1) cardiomyocytes were transfected with miR-155 analogues or inhibitors, then stimulated with angiotensin II to induce cardiac hypertrophy. miR-155 expression was revealed to be altered following transfection with chemically-modified miR-155 analogues and inhibitors in rat cardiomyocytes. In cell cardiac hypertrophy models, the cell surface area, AGTR1, atrial natriuretic peptide and myosin heavy chain-ß mRNA expression levels were revealed to be lower in cells stimulated with miR-155 analogue-transfected cells treated with angiotensin II compared with cells stimulated with angiotensin alone (P<0.05), as determined using reverse transcription-polymerase chain reaction (PCR), quantitative PCR and western blot analyses. Furthermore, calcineurin mRNA and protein, intracellular free calcium and nuclear factor of activated T-cells-4 proteins were downregulated in miR-155 analogue-transfected cells treated with angiotensin II, as compared with cells stimulated with angiotensin II alone (P<0.05). In conclusion, the current study indicates that miR-155 may improve cardiac hypertrophy by downregulating AGTR1 and suppressing the calcium signaling pathways activated by AGTR1.