Extracellular Ubiquitin Increases Expression of Angiogenic Molecules and Stimulates Angiogenesis in Cardiac Microvascular Endothelial Cells

Abstract

Objective Extracellular ubiquitin (Ub) is an immune modulator that plays a role in suppression of inflammation, organ injury, myocyte apoptosis and fibrosis. The purpose of this study was to investigate the effects of extracellular Ub on the process of cardiac angiogenesis. Methods Cardiac microvascular endothelial cells (CMECs) and aortic tissue were isolated from rats to measure changes in angiogenic protein levels and to assess angiogenic responses to extracellular Ub. Results In CMECs, extracellular Ub increased protein levels of vascular endothelial growth factor-A (VEGF-A) and matrix metalloproteinase-2 (MMP-2), known angiogenesis regulators. CMECs demonstrated enhanced rearrangement of fibrillar actin and migration in response to Ub treatment. Ub-treated CMECs demonstrated an increase in tube network formation which was inhibited by the CXCR4 receptor antagonist, AMD3100. Methylated Ub, unable to form polyubiquitin chains, enhanced tube network formation. Aortic ring sprouting assays demonstrated that Ub increases microvessel sprouting in the Matrigel. Conclusion The results of our study suggest a novel role for extracellular Ub in cardiac angiogenesis, providing evidence that extracellular Ub, at least in part acting via the CXCR4 receptor, has the potential to facilitate the process of angiogenesis in myocardial endothelial cells.

Functional and structural consequences of chemokine (C-X-C motif) receptor 4 activation with cognate and non-cognate agonists

“…3G). It has been previously reported that ubiquitin induces chemotaxis in B16-F10 (skin melanoma), 4T1 (breast cancer), RM-9 (prostate cancer) cells and regulates movements of isolated rat cardiac microvascular endothelial cells via CXCR4 [7, 9]. Thus, our findings confirm previous observations and suggest that ubiquitin and CXCL12 activate CXCR4, which then couples to Gα i to induce chemotaxis in primary human cells of hematopoietic and non-hematopoietic origin.…”

Heteromerization of chemokine (C-X-C motif) receptor 4 with α1A/B-adrenergic receptors controls α1-adrenergic receptor function

“…This implies that CXCR4 and also ACKR3 function as modulators of α 1 -AR. Whereas the molecular mechanisms through which ACKR3 influences α 1 -AR function remain to be determined, the observed effects of ubiquitin in the present study are in agreement with the findings that ubiquitin functions as a noncognate CXCR4 agonist that does not bind to ACKR3 (51,52,(59)(60)(61)(62)(63). The observation that CXCL12, which has a much higher affinity for ACKR3 than for CXCR4 (64), also enhanced the potency of PE in normal animals in vivo in the present study, whereas CXCL12 previously desensitized PE-mediated vasoconstriction of isolated arteries and reduced blood pressure during hemorrhagic shock (9), suggests that effects of CXCL12 depend on the relative functional contribution of CXCR4 and ACKR3 within the specific experimental or (patho)physiological environment (65).…”

Assessment of Right Ventricular Function in the Research Setting: Knowledge Gaps and Pathways Forward. An Official American Thoracic Society Research Statement

“…Animal models support potential roles for hypoxiainducible factor and vascular endothelial growth factor (65,207,209), although these pathways may be impaired in RVF (64,119). Recent studies identified additional potential proangiogenic regulators in the LV (e.g., PlGF, NF-kB [nuclear factor-kB], extracellular ubiquitin, STAT3, Nrf2, and Ang-2/Tie-2) (197,(212)(213)(214)(215)(216), but these have not been studied in the RV. A potential regulatory role for the proangiogenic microRNA miR-126 in RV capillary rarefaction was recently shown (217).…”