Rationale 20-Hydroxyeicosatetraenoic acid (20-HETE), one of the principle cytochrome P450 (CYP) eicosanoids, is a potent vasoactive lipid whose vascular effects include stimulation of smooth muscle contractility, migration and proliferation, as well as endothelial cell dysfunction and inflammation. Increased levels of 20-HETE in experimental animals and in humans are associated with hypertension, stroke, myocardial infarction and vascular diseases. Objective To date, a receptor/binding site for 20-HETE has been implicated based on the use of specific agonists and antagonists. The present study was undertaken to identify a receptor to which 20-HETE binds and through which it activates a signaling cascade that culminates in many of the functional outcomes attributed to 20-HETE in vitro and in vivo. Methods and Results Using crosslinking analogs, click chemistry, binding assays, and functional assays, we identified GPR75, currently an orphan G-protein coupled receptor (GPCR), as a specific target of 20-HETE. In cultured human endothelial cells, 20-HETE binding to GPR75 stimulated Gαq/11 protein dissociation and increased inositol phosphate (IP-1) accumulation as well as GPCR-kinase interacting protein-1 (GIT1)-GPR75 binding, which further facilitated the c-Src-mediated transactivation of endothelial EGFR. This results in downstream signaling pathways which induce angiotensin-converting enzyme (ACE) expression and endothelial dysfunction. Knockdown of GPR75 or GIT1 prevented 20-HETE-mediated endothelial growth factor receptor (EGFR) phosphorylation and ACE induction. In vascular smooth muscle cells, GPR75-20-HETE pairing is associated with Gαq/11- and GIT1-mediated protein kinase C (PKC)-stimulated phosphorylation of MaxiKβ, λinking GPR75 activation to 20-HETE-mediated vasoconstriction. GPR75 knockdown in a mouse model of 20-HETE-dependent hypertension prevented blood pressure elevation and 20-HETE-mediated increases in ACE expression, endothelial dysfunction, smooth muscle contractility and vascular remodeling. Conclusions This is the first report to identify a GPCR target for an eicosanoid of this class. The discovery of 20-HETE-GPR75 pairing presented here provides the molecular basis for the signaling and pathophysiological functions mediated by 20-HETE in hypertension and cardiovascular diseases.

Increased vascular 20-HETE is associated with hypertension and activation of the reninangiotensin system (RAS) through induction of vascular angiotensinconverting enzyme (ACE) expression. Cyp4a12tg mice, whose Cyp4a12-20-HETE synthase expression is under the control of a tetracycline (doxycycline, DOX) promoter, were used to assess the contribution of ACE/RAS to microvascular remodeling in 20-HETEdependent hypertension. Treatment of Cyp4a12tg mice with DOX increased systolic blood pressure (SBP; 136 Ϯ 2 vs. 102 Ϯ 1 mmHg; P Ͻ 0.05), and this increase was prevented by administration of 20-HEDGE, lisinopril, or losartan. DOX-induced hypertension was associated with microvascular dysfunction and remodeling of preglomerular microvessels, which was prevented by 20-HEDGE, a 20-HETE antagonist, yet only lessened, but not prevented, by lisinopril or losartan. In ACE 3/3 mice, which lack vascular endothelial ACE, administration of 5␣-dihydrotestosterone (DHT), a known inducer of 20-HETE production, increased SBP; however, the increase was about 50% of that in wild-type (WT) mice (151 Ϯ 1 vs. 126 Ϯ 1 mmHg). Losartan and 20-HEDGE prevented the DHT-induced increase in SBP in WT and ACE 3/3 mice. DHT treatment increased 20-HETE production and microvascular remodeling in WT and ACE 3/3 mice; however, remodeling was attenuated in the ACE 3/3 mice as opposed to WT mice (15.83 Ϯ 1.11 vs. 22.17 Ϯ 0.92 m; P Ͻ 0.05). 20-HEDGE prevented microvascular remodeling in WT and ACE 3/3 mice, while losartan had no effect on microvascular remodeling in ACE 3/3. Taken together, these results suggest that RAS contributes to 20-HETE-mediated microvascular remodeling in hypertension and that 20-HETE-driven microvascular remodeling independent of blood pressure elevation does not fully rely on ACE activity in the vascular endothelium.20-HETE; angiotensin II; ACE; vascular remodeling; hypertension; angiotensin-converting enzyme 20-HETE IS THE -HYDROXYLATION product of arachidonic acid metabolism by enzymes of the cytochrome P-450 (CYP) 4A and 4F families. It has been recognized as an eicosanoid of the microcirculation with renal, cerebral, cardiac, and mesenteric arteries having been shown to be rich sources of 20-HETE. Its effects on vascular function are multifaceted and include stimulation of smooth muscle contractility, migration, and proliferation, as well as activation of endothelial cell dysfunction, angiogenesis, and inflammation (1, 2, 4, 21, 34, 36). Such effects could have significant implications with regard to the development of hypertension and its cardiovascular complications. Indeed, numerous studies in experimental models of hypertension have documented a close relationship between increased vascular production of 20-HETE and blood pressure elevation. Models of 20-HETE-driven hypertension also exhibit vascular injury that is exemplified by endothelial and vascular dysfunction (11,15,17,33,35).Vascular remodeling is both a product of and contributor to the development of hypertension. This process is promoted by a variety of stimuli...

Purpose-Recent studies have shown that 20-hydroxyeicosatetraenoic acid (20-HETE) is a key molecule in sustaining androgen-mediated prostate cancer cell survival. Thus, the aim of this study was to determine whether 20-HETE can affect the metastatic potential of androgen-insensitive prostate cancer cells, and the implication of the newly described 20-HETE receptor, GPR75, in mediating these effects.Methods-The expression of GPR75, protein phosphorylation, actin polymerization and protein distribution were assessed by western blot and/or fluorescence microscopy. Additionally, in vitro assays including epithelial-mesenchymal transition (EMT), metalloproteinase-2 (MMP-2) activity, scratch wound healing, transwell invasion and soft agar colony formation were used to evaluate the effects of 20-HETE agonists/antagonists or GPR75 gene silencing on the aggressive features of PC-3 cells.

Cross-coupling reactions are a staple in organic synthesis, especially for C-C bond formation with sp- and sp-carbon electrophiles. In recent years, the range of accessible C-C bonds has been extended to stereogenic centers which expedites access to greater molecular complexity. However, these reactions predominantly depend upon late transition metal (LTM) catalysts whose cost, toxicity, and/or environmental impact have come under increasing scrutiny and governmental regulation. Here, we report Mn(II)Cl complexes alone, or with assistance from copper, catalyze the stereospecific cross-coupling of α-alkoxyalkylstannanes with organic electrophiles with complete retention of configuration.

Maintenance of a healthy pool of mitochondria is important for the function and survival of terminally differentiated cells such as cardiomyocytes. Epoxyeicosatrienoic acids (EETs) are epoxy lipids derived from metabolism of arachidonic acid by cytochrome P450 epoxygenases. We have previously shown that EETs trigger a protective response limiting mitochondrial dysfunction and reducing cellular death. The aim of this study was to investigate whether EET-mediated effects influence mitochondrial quality in HL-1 cardiac cells during starvation. HL-1 cells were subjected to serum- and amino acid free conditions for 24h. We employed a dual-acting synthetic analog UA-8 (13-(3-propylureido)tridec-8-enoic acid), possessing both EET-mimetic and soluble epoxide hydrolase (sEH) inhibitory properties, or 14,15-EET as model EET molecules. We demonstrated that EET-mediated events significantly improved mitochondrial function as assessed by preservation of the ADP/ATP ratio and oxidative respiratory capacity. Starvation induced mitochondrial hyperfusion observed in control cells was attenuated by UA-8. However, EET-mediated events did not affect the expression of mitochondrial dynamic proteins Fis1, DRP-1 or Mfn2. Rather we observed increased levels of OPA-1 oligomers and increased mitochondrial cristae density, which correlated with the preserved mitochondrial function. Increased DNA binding activity of pCREB and Nrf1/2 and increased SIRT1 activity together with elevated mitochondrial proteins suggest EET-mediated events led to preserved mitobiogenesis. Thus, we provide new evidence for EET-mediated events that preserve a healthier pool of mitochondria in cardiac cells following starvation-induced stress.