Heat shock protein-27 and sex-selective regulation of muscarinic and proteinase-activated receptor 2-mediated vasodilatation: differential sensitivity to endothelial NOS inhibition

Polynorepinephrine nanoparticles activate vascular smooth muscle alpha-1 adrenergic receptors

Biocompatible polymeric nanoparticles (NPs) as carriers for therapeutic agents with multifunctional activities have received unprecedented attention for a variety of bio-pharmaceutical applications. We describe the synthesis, the fluorescence properties, the bio-compatible nature and the alpha-1 adrenergic receptor bio-activity of engineered quantum dot-like polynorepinephrine (PNE) NPs. The spherical PNE NPs, which are internalized in smooth muscle cells via a receptor-selective mechanism, activate alpha-1-adrenoceptors in intact mouse aorta and aorta-derived cultured smooth muscle cells, leading to the activation of calcium signaling/contraction and stimulation of mitogen-activated protein kinase (MAPK), thereby displaying receptor-triggering biological activity, possibly acting both extracellularly and intracellularly. Our data indicate that NPs generated by the polymerization of pharmacologically active compounds like norepinephrine can retain receptor-selective biological activity coupled to inherent fluorescence.

Mechanistic insights into heat shock protein 27, a potential therapeutic target for cardiovascular diseases

Heat shock protein 27 (HSP27) is a small chaperone protein that is overexpressed in a variety of cellular stress states. It is involved in regulating proteostasis and protecting cells from multiple sources of stress injury by stabilizing protein conformation and promoting the refolding of misfolded proteins. Previous studies have confirmed that HSP27 is involved in the development of cardiovascular diseases and plays an important regulatory role in this process. Herein, we comprehensively and systematically summarize the involvement of HSP27 and its phosphorylated form in pathophysiological processes, including oxidative stress, inflammatory responses, and apoptosis, and further explore the potential mechanisms and possible roles of HSP27 in the diagnosis and treatment of cardiovascular diseases. Targeting HSP27 is a promising future strategy for the treatment of cardiovascular diseases.

Hsp20 Promotes Endothelial Progenitor Cell Angiogenesis via Activation of PI3K/Akt Signaling Pathway under Hypoxia

BACKGROUND

Mandibular distraction osteogenesis (MDO) is a kind of endogenous tissue engineering technology that lengthens the jaw and opens airway so that a patient can breathe safely and comfortably on his or her own. Endothelial progenitor cells (EPCs) are crucial for MDO-related angiogenesis. Moreover, emerging evidence suggests that heat shock protein 20 (Hsp20) modulates angiogenesis under hypoxic conditions. However, the specific role of Hsp20 in EPCs, in the context of MDO, is not yet known. The aim of this study was to explore the expression of Hsp20 during MDO and the effects of Hsp20 on EPCs under hypoxia.

METHODS

Mandibular distraction osteogenesis and mandibular bone defect (MBD) canine model were established. The expression of CD34, CD133, HIF-1α, and Hsp20 in callus was detected by immunofluorescence on day 14 after surgery. Canine bone marrow EPCs were cultured, with or without optimal cobalt chloride (CoCl2) concentration. Hypoxic effects, caused by CoCl2, were evaluated by means of the cell cycle, cell apoptosis, transwell cell migration, and tube formation assays. The Hsp20/KDR/PI3K/Akt expression levels were evaluated via immunofluorescence, RT-qPCR, and western blot. Next, EPCs were incorporated with either Hsp20-overexpression or Hsp20-siRNA lentivirus. The resulting effects were evaluated as described above.

RESULTS

CD34, CD133, HIF-1α, and Hsp20 were displayed more positive in the callus of MDO compared with MBD. In addition, hypoxic conditions, generated by 0.1 mM CoCl2, in canine EPCs, accelerated cell proliferation, migration, tube formation, and Hsp20 expression. Hsp20 overexpression in EPCs significantly stimulated cell proliferation, migration, and tube formation, whereas Hsp20 inhibition produced the opposite effect. Additionally, the molecular mechanism was partly dependent on the KDR/PI3K/Akt pathway.

CONCLUSION

In summary, herein, we present a novel mechanism of Hsp20-mediated regulation of canine EPCs via Akt activation in a hypoxic microenvironment.

Metformin Prevents Hyperglycemia-Associated, Oxidative Stress-Induced Vascular Endothelial Dysfunction: Essential Role for the Orphan Nuclear Receptor Human Nuclear Receptor 4A1 (Nur77)

Vascular pathology is increased in diabetes because of reactive-oxygen-species (ROS)-induced endothelial cell damage. We found that in vitro and in a streptozotocin diabetes model in vivo, metformin at diabetes-therapeutic concentrations (1-50 µM) protects tissue-intact and cultured vascular endothelial cells from hyperglycemia/ROS-induced dysfunction typified by reduced agonist-stimulated endothelium-dependent, nitric oxide-mediated vasorelaxation in response to muscarinic or proteinase-activated-receptor 2 agonists. Metformin not only attenuated hyperglycemia-induced ROS production in aorta-derived endothelial cell cultures but also prevented hyperglycemia-induced endothelial mitochondrial dysfunction (reduced oxygen consumption rate). These endothelium-protective effects of metformin were absent in orphan-nuclear-receptor Nr4a1-null murine aorta tissues in accord with our observing a direct metformin-Nr4a1 interaction. Using in silico modeling of metformin-NR4A1 interactions, Nr4a1-mutagenesis, and a transfected human embryonic kidney 293T cell functional assay for metformin-activated Nr4a1, we identified two Nr4a1 prolines, P505/P549 (mouse sequences corresponding to human P501/P546), as key residues for enabling metformin to affect mitochondrial function. Our data indicate a critical role for Nr4a1 in metformin's endothelial-protective effects observed at micromolar concentrations, which activate AMPKinase but do not affect mitochondrial complex-I or complex-III oxygen consumption rates, as does 0.5 mM metformin. Thus, therapeutic metformin concentrations requiring the expression of Nr4a1 protect the vasculature from hyperglycemia-induced dysfunction in addition to metformin's action to enhance insulin action in patients with diabetes. SIGNIFICANCE STATEMENT: Metformin improves diabetic vasodilator function, having cardioprotective effects beyond glycemic control, but its mechanism to do so is unknown. We found that metformin at therapeutic concentrations (1-50µM) prevents hyperglycemia-induced endothelial dysfunction by attenuating reactive oxygen species-induced damage, whereas high metformin (>250 µM) impairs vascular function. However, metformin's action requires the expression of the orphan nuclear receptor NR4A1/Nur77. Our data reveal a novel mechanism whereby metformin preserves diabetic vascular endothelial function, with implications for developing new metformin-related therapeutic agents.

Heat shock protein 27 activity is linked to endothelial barrier recovery after proinflammatory GPCR-induced disruption

Vascular inflammation causes endothelial barrier disruption and tissue edema. Several inflammatory mediators act through G protein–coupled receptors (GPCRs), including protease-activated receptor-1 (PAR1), to elicit inflammatory responses. The activation of PAR1 by its ligand thrombin stimulates proinflammatory, p38 mitogen-activated protein kinase (MAPK) signaling that promotes endothelial barrier disruption. Through mass spectrometry phosphoproteomics, we identified heat shock protein 27 (HSP27), which exists as a large oligomer that binds to actin, as a promising candidate for the p38-mediated regulation of barrier integrity. Depletion of HSP27 by siRNA enhanced endothelial cell barrier permeability and slowed recovery after thrombin stimulation. We further showed that two effector kinases of p38 MAPK, MAPKAPK2 (MK2) and MAPKAPK3 (MK3), differentially phosphorylated HSP27 at Ser15, Ser78, and Ser82. Whereas inhibition of thrombin-stimulated p38 activation blocked HSP27 phosphorylation at all three sites, inhibition of MK2 reduced the phosphorylation of only Ser15 and Ser78. Inhibition of both MK2 and MK3 was necessary to attenuate Ser82 phosphorylation. Thrombin-stimulated p38-MK2-MK3 signaling induced HSP27 oligomer disassembly. However, a phosphorylation-deficient mutant of HSP27 exhibited defective oligomer disassembly and altered the dynamics of barrier recovery after thrombin stimulation. Moreover, blocking HSP27 oligomer reassembly with the small-molecule inhibitor J2 enhanced endothelial barrier permeability in vitro and vascular leakage in vivo in response to PAR1 activation. These studies reveal the distinct regulation of HSP27 phosphorylation and function induced by the GPCR-stimulated p38-MK2-MK3 signaling axis that controls the dynamics of endothelial barrier recovery in vitro and vascular leakage in vivo.

Single-cell RNA sequencing reveals cell type- and artery type-specific vascular remodelling in male spontaneously hypertensive rats

AIMS

Hypertension is a major risk factor for cardiovascular diseases. However, vascular remodelling, a hallmark of hypertension, has not been systematically characterized yet. We described systematic vascular remodelling, especially the artery type- and cell type-specific changes, in hypertension using spontaneously hypertensive rats (SHRs).

METHODS AND RESULTS

Single-cell RNA sequencing was used to depict the cell atlas of mesenteric artery (MA) and aortic artery (AA) from SHRs. More than 20 000 cells were included in the analysis. The number of immune cells more than doubled in aortic aorta in SHRs compared to Wistar Kyoto controls, whereas an expansion of MA mesenchymal stromal cells (MSCs) was observed in SHRs. Comparison of corresponding artery types and cell types identified in integrated datasets unravels dysregulated genes specific for artery types and cell types. Intersection of dysregulated genes with curated gene sets including cytokines, growth factors, extracellular matrix (ECM), receptors, etc. revealed vascular remodelling events involving cell-cell interaction and ECM re-organization. Particularly, AA remodelling encompasses upregulated cytokine genes in smooth muscle cells, endothelial cells, and especially MSCs, whereas in MA, change of genes involving the contractile machinery and downregulation of ECM-related genes were more prominent. Macrophages and T cells within the aorta demonstrated significant dysregulation of cellular interaction with vascular cells.

CONCLUSION

Our findings provide the first cell landscape of resistant and conductive arteries in hypertensive animal models. Moreover, it also offers a systematic characterization of the dysregulated gene profiles with unbiased, artery type-specific and cell type-specific manners during hypertensive vascular remodelling.

The pregnane X receptor and its microbiota-derived ligand indole 3-propionic acid regulate endothelium-dependent vasodilation

We proposed that circulating metabolites generated by the intestinal microbiota can affect vascular function. One such metabolite, indole 3-propionic acid (IPA), can activate the pregnane X receptor(PXR), a xenobiotic-activated nuclear receptor present in many tissues, including the vascular endothelium. We hypothesized that IPA could regulate vascular function by modulating PXR activity. To test this, Pxr^+/+ mice were administered broad-spectrum antibiotics for 2 wk with IPA supplementation. Vascular function was evaluated by bioassay using aorta and pulmonary artery ring tissue from antibiotic-treated Pxr^+/+ and Pxr^-/-mice, supplemented with IPA, and using aorta tissue maintained in organ culture for 24 h in the presence of IPA. Endothelium-dependent, nitric oxide(NO)-mediated muscarinic and proteinase-activated receptor 2(PAR2)-stimulated vasodilation was assessed. Endothelial nitric oxide synthase (eNOS) abundance was evaluated in intact tissue or in aorta-derived endothelial cell cultures from Pxr^+/+ and Pxr^-/- mice, and vascular Pxr levels were assessed in tissues obtained from Pxr^+/+ mice treated with antibiotics and supplemented with IPA. Antibiotic-treated Pxr^+/+ mice exhibited enhanced agonist-induced endothelium-dependent vasodilation, which was phenocopied by tissues from either Pxr^-/- or germ-free mice. IPA exposure reduced the vasodilatory responses in isolated and cultured vessels. No effects of IPA were observed for tissues obtained from Pxr^-/- mice. Serum nitrate levels were increased in antibiotic-treated Pxr^+/+and Pxr^-/- mice. eNOS abundance was increased in aorta tissues and cultured endothelium from Pxr^-/- mice. PXR stimulation reduced eNOS expression in cultured endothelial cells from Pxr^+/+ but not Pxr^-/- mice. The microbial metabolite IPA, via the PXR, plays a key role in regulating endothelial function. Furthermore, antibiotic treatment changes PXR-mediated vascular endothelial responsiveness by upregulating eNOS.

Validation of Housekeeping Genes as Reference for Reverse-Transcription-qPCR Analysis in Busulfan-Injured Microvascular Endothelial Cells

Endothelial cells (ECs) could express some important cytokines and signal molecules which play a key role in normal hematopoiesis and repopulation. Busulfan-induced vascular endothelial injury is an important feature after hematopoietic stem cell transplantation (HSCT). But the molecular mechanism of how the injured ECs affect hematopoietic reconstruction is still unknown. It is possibly through modulation of the change of some gene expression. RT-qPCR is one of the most popular methods used to accurately determine gene expression levels, based on stable reference gene (RG) selection from housekeeping genes. So our aim is to select stable RGs for more accurate measures of mRNA levels during Busulfan-induced vascular endothelial injury. In this study, 14 RGs were selected to investigate their expression stability in ECs during 72 hours of EC injury treated with Busulfan. Our results revealed extreme variation in RG stability compared by five statistical algorithms. ywhaz and alas1 were recognized as the two idlest RGs on account of the final ranking, while the two most usually used RGs (gapdh and actb) were not the most stable RGs. Next, these data were verified by testing signalling pathway genes ctnnb1, robo4, and notch1 based on the above four genes ywha, alas1, gapdh, and actb. It shows that the normalization of mRNA expression data using unstable RGs greatly affects gene fold change, which means the reliability of the biological conclusions is questionable. Based on the best RGs used, we also found that robo4 is significantly overexpressed in Busulfan-impaired ECs. In conclusion, our data reaffirms the importance of RGs selection for the valid analysis of gene expression in Busulfan-impaired ECs. And it also provides very useful guidance and basis for more accurate differential expression gene screening and future expanding biomolecule study of different drugs such as cyclophosphamide and fludarabine-injured ECs.

Heat shock protein-27 and sex-selective regulation of muscarinic and proteinase-activated receptor 2-mediated vasodilatation: differential sensitivity to endothelial NOS inhibition

BACKGROUND AND PURPOSE

Previously, we demonstrated that exogenous heat shock protein 27 (HSP27/gene, HSPB1) treatment of human endothelial progenitor cells (EPCs) increases the synthesis and secretion of VEGF, improves EPC-migration/re-endothelialization and decreases neo-intima formation, suggesting a role for HSPB1 in regulating EPC function. We hypothesized that HSPB1 also affects mature endothelial cells (ECs) to alter EC-mediated vasoreactivity in vivo. Our work focused on endothelial NOS (eNOS)/NO-dependent relaxation induced by ACh and the coagulation pathway-activated receptor, proteinase-activated receptor 2 (PAR2).

EXPERIMENTAL APPROACH

Aorta rings from male and female wild-type, HSPB1-null and HSPB1 overexpressing (HSPB1o/e) mice were contracted with phenylephrine, and NOS-dependent relaxation responses to ACh and PAR2 agonist, 2-furoyl-LIGRLO-NH₂ , were measured without and with L-NAME and ODQ, either alone or in combination to block NO synthesis/action. Tissues from female HSPB1-null mice were treated in vitro with recombinant HSP27 and then used for bioassay as above. Furthermore, oestrogen-specific effects were evaluated using a bioassay of aorta isolated from ovariectomized mice.

KEY RESULTS

Relative to males, HSPB1-null female mice exhibited an increased L-NAME-resistant relaxation induced by activation of either PAR2 or muscarinic ACh receptors that was blocked in the concurrent presence of both L-NAME and ODQ. mRNAs (qPCR) for eNOS and ODQ-sensitive guanylyl-cyclase were increased in females versus males. Treatment of isolated aorta tissue with HSPB1 improved tissue responsiveness in the presence of L-NAME. Ovariectomy did not affect NO sensitivity, supporting an oestrogen-independent role for HSPB1.

CONCLUSIONS AND IMPLICATIONS

HSPB1 can regulate intact vascular endothelial function to affect NO-mediated vascular relaxation, especially in females.