Inhibitory effect of D1-like dopamine receptors on neuropeptide Y-induced proliferation in vascular smooth muscle cells

An Overview on Renal and Central Regulation of Blood Pressure by Neuropeptide FF and Its Receptors

Neuropeptide FF (NPFF) is an endogenous octapeptide that was originally isolated from the bovine brain. It belongs to the RFamide family of peptides that has a wide range of physiological functions and pathophysiological effects. NPFF and its receptors, NPFFR1 and NPFFR2, abundantly expressed in rodent and human brains, participate in cardiovascular regulation. However, the expressions of NPFF and its receptors are not restricted within the central nervous system but are also found in peripheral organs, including the kidneys. Both NPFFR1 and NPFFR2 mainly couple to Gαi/o, which inhibits cyclic adenosine monophosphate (cAMP) production. NPFF also weakly binds to other RFamide receptors and the Mas receptor. Relevant published articles were searched in PubMed, Google Scholar, Web of Science, and Scopus. Herein, we review evidence for the role of NPFF in the regulation of blood pressure, in the central nervous system, particularly within the hypothalamic paraventricular nucleus and the brainstem, and the kidneys. NPFF is a potential target in the treatment of hypertension.

Renal autocrine neuropeptide FF (NPFF) signaling regulates blood pressure

The kidney and brain play critical roles in the regulation of blood pressure. Neuropeptide FF (NPFF), originally isolated from the bovine brain, has been suggested to contribute to the pathogenesis of hypertension. However, the roles of NPFF and its receptors, NPFF-R1 and NPFF-R2, in the regulation of blood pressure, via the kidney, are not known. In this study, we found that the transcripts and proteins of NPFF and its receptors, NPFF-R1 and NPFF-R2, were expressed in mouse and human renal proximal tubules (RPTs). In mouse RPT cells (RPTCs), NPFF, but not RF-amide-related peptide-2 (RFRP-2), decreased the forskolin-stimulated cAMP production in a concentration- and time-dependent manner. Furthermore, dopamine D1-like receptors colocalized and co-immunoprecipitated with NPFF-R1 and NPFF-R2 in human RPTCs. The increase in cAMP production in human RPTCs caused by fenoldopam, a D1-like receptor agonist, was attenuated by NPFF, indicating an antagonistic interaction between NPFF and D1-like receptors. The renal subcapsular infusion of NPFF in C57BL/6 mice decreased renal sodium excretion and increased blood pressure. The NPFF-mediated increase in blood pressure was prevented by RF-9, an antagonist of NPFF receptors. Taken together, our findings suggest that autocrine NPFF and its receptors in the kidney regulate blood pressure, but the mechanisms remain to be determined.

Dopamine D1 receptor activation ameliorates ox-LDL-induced endothelial cell senescence via CREB/Nrf2 pathway

Endothelial cell senescence is involved in endothelial dysfunction and aging-related vascular diseases. The D1-like dopamine receptor (DR1), a number of G-protein-coupled receptors, is currently under consideration as a potential therapeutic target for the prevention of atherosclerosis. However, the role of DR1 in regulating ox-LDL-stimulated endothelial cell senescence remains unknown. Here, we found that the elevated Prx hyperoxidation and reactive oxygen species (ROS) levels in ox-LDL-treated Human umbilical vein endothelial cells (HUVECs) were observed, suppressed by DR1 agonist SKF38393. Increased proportion of senescence-associated β-galactosidase (SA-β-gal) positive staining cells and activated p16/p21/p53 pathway in ox-LDL-treated HUVECs were significantly abolished by DR1 activation. In addition, SKF38393 increased the phosphorylation of cAMP response element-binding protein (CREB) at serine-133, nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and expression of HO-1 in HUVECs. In contrast, adding H-89, a PKA inhibitor, diminished the effects of DR1 activation. Further studies performed with DR1 siRNA confirmed that DR1 was involved in CREB/Nrf2 pathway. Taken together, DR1 activation reduces ROS production and cell senescence by upregulating CREB/Nrf2 antioxidant signaling in ox-LDL-induced endothelial cells. Thus, DR1 could be a potential molecular target to counteract oxidative stress-induced cellular senescence.

Segregated Nanocompartments Containing Therapeutic Enzymes and Imaging Compounds within DNA-Zipped Polymersome Clusters for Advanced Nanotheranostic Platform

Nanotheranostics is an emerging field that brings together nanoscale-engineered materials with biological systems providing a combination of therapeutic and diagnostic strategies. However, current theranostic nanoplatforms have serious limitations, mainly due to a mismatch between the physical properties of the selected nanomaterials and their functionalization ease, loading ability, or overall compatibility with bioactive molecules. Herein, a nanotheranostic system is proposed based on nanocompartment clusters composed of two different polymersomes linked together by DNA. Careful design and procedure optimization result in clusters segregating the therapeutic enzyme human Dopa decarboxylase (DDC) and fluorescent probes for the detection unit in distinct but colocalized nanocompartments. The diagnostic compartment provides a twofold function: trackability via dye loading as the imaging component and the ability to attach the cluster construct to the surface of cells. The therapeutic compartment, loaded with active DDC, triggers the cellular expression of a secreted reporter enzyme via production of dopamine and activation of dopaminergic receptors implicated in atherosclerosis. This two-compartment nanotheranostic platform is expected to provide the basis of a new treatment strategy for atherosclerosis, to expand versatility and diversify the types of utilizable active molecules, and thus by extension expand the breadth of attainable applications.

Inhibitory effect of D3 dopamine receptors on neuropeptide Y‑induced migration in vascular smooth muscle cells

Abnormal migration of vascular smooth muscle cells (VSMCs) serves an important role in hypertension, atherosclerosis and restenosis following angioplasty, which is regulated numerous hormonal and humoral factors, including neuropeptide Y (NPY) and dopamine. Dopamine and NPY are both sympathetic neurotransmitters, and a previous study reported that NPY increased VSMC proliferation, while dopamine receptor inhibited it. Therefore, the authors wondered whether or not there is an inhibitory effect of dopamine receptor on NPY‑mediated VSMC migration. The present study demonstrated that stimulation with NPY dose‑dependence (10‑10‑10‑7M, 24 h) increased VSMC migration, the stimulatory effect of NPY was via the Y1 receptor. This is because, in the presence of the Y1 receptor antagonist, BIBP3226 (10‑7 M), the stimulatory effect of NPY on VSMC migration was blocked. Activation of the D3 receptor by PD128907 dose‑dependence (10‑11‑10‑8 M) reduced the stimulatory effect of NPY on VSMC migration. The effect of PD128907 was via the D3 receptor, because the inhibitory effect of PD128907 on NPY‑mediated migration was blocked by the D3 receptor antagonist, U99194. The authors' further study suggested that the inhibitory effect of the D3 receptor was via the PKA signaling pathway, in the presence of the PKA inhibitor, 14‑22 (10‑6 M), the inhibitory effect of PD128907 on VSMC migration was blocked. Moreover, the inhibitory effect of PD128907 was imitated by PKA activator, Sp‑cAMP [S], in the presence of Sp‑cAMP [S], the NPY‑mediated stimulatory effect on VSMC migration was abolished. The present study indicated that activation of the D3 receptor inhibits NPY Y1‑mediated migration on VSMCs, PKA is involved in the signaling pathway.

Different effects of neuropeptide Y on proliferation of vascular smooth muscle cells via regulation of Geminin

The proliferation-promoting effect of neuropeptide Y (NPY) always functions in low-serum-cultured vascular smooth muscle cells (VSMCs), and the phenotypic switch of VSMCs is regulated by concentrations of serum. Whether the property of the NPY proliferative effect in VSMCs relies on phenotype of VSMCs is unclear. We aimed to explore the role of NPY on proliferation of different VSMC phenotypes in the pathogenesis of atherosclerosis. By stimulating A10 cells with 200 nM NPY in 0.5 or 10% serum, 3H-thymidine and 5-ethynyl-2'-deoxyuridine (EdU) and CCK8 measurements were used to detect VSMC proliferation. RT-PCR and Flow cytometry were performed to detect the factors involved in different properties of the NPY proliferative effect in VSMCs. Instead of facilitating proliferation, NPY had no significant effect on the growth of VSMCs when cultured in 10% serum (VSMCs stayed at synthetic states). The underlying mechanism may be involved in down-regulation of Y1 receptor (P < 0.05 vs. Vehicle) and up-regulation of Geminin (P < 0.05 vs. Vehicle) in 10% serum-cultured VSMCs co-incubated with 200 nM NPY. Besides, modulation of Geminin was effectively blocked by the Y1 receptor antagonist. The stimulation of NPY on proliferation of VSMCs could be a double-edged sword in the development of atherosclerosis and thus provides new knowledge for therapy of atherosclerosis.