Signaling switch of the urotensin II vasosactive peptide GPCR: prototypic chemotaxic mechanism in glioma

Prognostic Significance and Functional Mechanism of UTS2 in Glioblastoma Multiforme

AIM

We aimed to explore the role of urotensin 2 (UTS2) in glioblastoma (GBM).

BACKGROUND

GBM is the most malignant primary brain cancer with a poor prognosis. Previous studies have suggested that GBM vessels undergo dynamic remodeling modulated by tumor vasodilation and vasoconstriction instead of tumor angiogenesis.

OBJECTIVE

Here, we have first investigated the expression and function of UTS2, a potent vasoconstrictor, in GBM.

METHODS

The mRNA expression profiles and clinical information of GBM patients were obtained from the TCGA database. The clinical relevance of UTS2 was explored by the Mann-Whitney U test and Cox hazard regression survival test. We further explored the role of UTS2 in GBM cell proliferation, migration, and tumor immune microenvironment. Moreover, we established the in vivo mice model to validate its oncogenic effects on GBM progression.

RESULTS

Although we did not find significant correlations between UTS2 expression and patients' clinical characteristics, UTS2 was identified as a valid independent prognostic indicator according to multivariate survival analysis. Knockdown of UTS2 resulted in decreased GBM cell proliferation and migration. In addition, functional enrichment analysis implied UTS2 to be involved in the regulation of the immune microenvironment. In vivo studies showed that UTS2 knockdown suppressed GBM xenograft growth, highlighting the tumor-promoting effects of UTS2 on GBM.

CONCLUSION

Our study identified that UTS2 could predict the prognosis of GBM patients and provided evidence regarding its oncogenic effects both in vitro and in vivo.

The urotensin II receptor triggers an early meningeal response and a delayed macrophage-dependent vasospasm after subarachnoid hemorrhage in male mice

Subarachnoid hemorrhage (SAH) can be associated with neurological deficits and has profound consequences for mortality and morbidity. Cerebral vasospasm (CVS) and delayed cerebral ischemia affect neurological outcomes in SAH patients, but their mechanisms are not fully understood, and effective treatments are limited. Here, we report that urotensin II receptor UT plays a pivotal role in both early events and delayed mechanisms following SAH in male mice. Few days post-SAH, UT expression is triggered by blood or hemoglobin in the leptomeningeal compartment. UT contributes to perimeningeal glia limitans astrocyte reactivity, microvascular alterations and neuroinflammation independent of CNS-associated macrophages (CAMs). Later, CAM-dependent vascular inflammation and subsequent CVS develop, leading to cognitive dysfunction. In an SAH model using humanized UTh+/h+ male mice, we show that post-SAH CVS and behavioral deficits, mediated by UT through Gq/PLC/Ca2+ signaling, are prevented by UT antagonists. These results highlight the potential of targeting UT pathways to reduce early meningeal response and delayed cerebral ischemia in SAH patients.

Combination of Docking-Based and Pharmacophore-Based Virtual Screening Identifies Novel Agonists That Target the Urotensin Receptor

The urotensin receptor (UT receptor), a G-protein-coupled receptor mediating urotensin-II and urotensin-II-related peptide signaling in the urotensinergic system, has multiple pharmacological activities. However, there is no drug targeting the UT receptor currently in clinical use, and the discovery of new leads is still important. The complete crystal structure of the UT receptor has not yet been resolved and a screening strategy combining multiple methods can improve the accuracy and efficiency of drug screening. This study aimed to identify novel UT receptor agonists using a combination of docking-based, pharmacophore-based, and cell-based drug screening. First, the three-dimensional structures of the UT receptor were constructed through single-template, multi-template homologous modeling and threading strategies. After structure evaluation and ligand enrichment analysis, a model from the threading modeling was selected for docking-based virtual screening based on stepwise filtering, and 1368 positive compounds were obtained from our compound library. Second, the pharmacophore models were constructed using known ligands targeting the UT receptor for pharmacophore-based virtual screening. A model was selected after model validation, and 300 positive compounds were retrieved. Then, after intersecting the results of two different virtual screening methods with 570 compound entities from our primary screening, 14 compounds were obtained. Finally, three hits were obtained after in vitro confirmation. Furthermore, preliminary evaluation of the hits showed that they influenced glucose consumption. In summary, by integrating docking-based, pharmacophore-based, and in vitro drug screening, three new agonists targeting the UT receptor were identified which may serve as promising therapeutic agents for urotensinergic system disorders.

GPCR genes as a predictor of glioma severity and clinical outcome

OBJECTIVE

To undertake a comprehensive analysis of the differential expression of the G protein-coupled receptor (GPCR) genes in order to construct a GPCR gene signature for human glioma prognosis.

METHODS

This current study investigated several glioma transcriptomic datasets and identified the GPCR genes potentially associated with glioma severity.

RESULTS

A gene signature comprising 13 GPCR genes (nine upregulated and four downregulated genes in high-grade glioma) was developed. The predictive power of the 13-gene signature was tested in two validation cohorts and a strong positive correlation (Spearman's rank correlation test: ρ = 0.649 for the Validation1 cohort; ρ = 0.693 for the Validation2 cohort) was observed between the glioma grade and 13-gene based severity score in both cohorts. The 13-gene signature was also predictive of glioma prognosis based on Kaplan-Meier survival curve analyses and Cox proportional hazard regression analysis in four cohorts of patients with glioma.

CONCLUSIONS

Knowledge of GPCR gene expression in glioma may help researchers gain a better understanding of the pathogenesis of high-grade glioma. Further studies are needed to validate the association between these GPCR genes and glioma pathogenesis.

The core autophagy protein ATG9A controls dynamics of cell protrusions and directed migration

Chemotactic migration is a fundamental cellular behavior relying on the coordinated flux of lipids and cargo proteins toward the leading edge. We found here that the core autophagy protein ATG9A plays a critical role in the chemotactic migration of several human cell lines, including highly invasive glioma cells. Depletion of ATG9A protein altered the formation of large and persistent filamentous actin (F-actin)-rich lamellipodia that normally drive directional migration. Using live-cell TIRF microscopy, we demonstrated that ATG9A-positive vesicles are targeted toward the migration front of polarized cells, where their exocytosis correlates with protrusive activity. Finally, we found that ATG9A was critical for efficient delivery of β1 integrin to the leading edge and normal adhesion dynamics. Collectively, our data uncover a new function for ATG9A protein and indicate that ATG9A-positive vesicles are mobilized during chemotactic stimulation to facilitate expansion of the lamellipodium and its anchorage to the extracellular matrix.

Gα12 and Gα13: Versatility in Physiology and Pathology

G protein-coupled receptors (GPCRs), as the largest family of receptors in the human body, are involved in the pathological mechanisms of many diseases. Heterotrimeric G proteins represent the main molecular switch and receive cell surface signals from activated GPCRs. Growing evidence suggests that Gα₁₂ subfamily (Gα_12/13)-mediated signaling plays a crucial role in cellular function and various pathological processes. The current research on the physiological and pathological function of Gα_12/13 is constantly expanding, Changes in the expression levels of Gα_12/13 have been found in a wide range of human diseases. However, the mechanistic research on Gα_12/13 is scattered. This review briefly describes the structural sequences of the Gα_12/13 isoforms and introduces the coupling of GPCRs and non-GPCRs to Gα_12/13. The effects of Gα_12/13 on RhoA and other signaling pathways and their roles in cell proliferation, migration, and immune cell function, are discussed. Finally, we focus on the pathological impacts of Gα_12/13 in cancer, inflammation, metabolic diseases, fibrotic diseases, and circulatory disorders are brought to focus.

Hyaluronic acid-based hydrogels loaded with chemoattractant and anticancer drug - new formulation for attracting and tackling glioma cells

Over the last few years, significant interest has emerged in the development of localised therapeutic strategies for the treatment of glioblastoma (GBM). The concept of attracting and trapping residual tumour cells within a confined area to facilitate their eradication has developed progressively. Herein, we propose a new design of hyaluronic acid-based hydrogel which can be utilized as a matrix containing a soluble chemoattractant to attract residual glioma cells and chemotherapeutic agents to eradicate them in a less invasive and more efficient way compared to the currently available methods. Hydrogels were prepared at different crosslinking densities, e.g. low and high density, by crosslinking hyaluronic acid with various concentrations of adipic acid dihydrazide and U87MG GBM cell morphology, survival and CD44 expression were evaluated. As a proof-of-concept, hydrogels were loaded with a small peptide chemokine, human urotensin II (hUII), and the migration and survival of U87MG GBM cells were studied. Chemoattractant-containing hydrogels were also loaded with chemotherapeutic drugs to promote cell death in culture. The results showed that U87MG cells were able to invade the hydrogel network and to migrate in response to the chemoattractant hUII. In addition, in static condition, hydrogels loaded with doxorubicin demonstrated significant cytotoxicity leading to less than 80% U87MG cell viability after 48 hours when compared to the control sample. In addition, in in vitro invasive assays, it was originally shown that the chemoattractant effect of hUII can be effective before the cytotoxic action of doxorubicin on the U87MG cells trapped in the hydrogel. Our results provide new insights into a promising approach which can be readily translated in vivo for the treatment of one of the most devastating brain tumours.

Urantide Improves Cardiac Function, Modulates Systemic Cytokine Response, and Increases Survival in A Murine Model of Endotoxic Shock

INTRODUCTION

Urotensin II is a potent vasoactive peptide activating the the G protein-coupled urotensin II receptor UT, and is involved in systemic inflammation and cardiovascular functions. The aim of our work was to study the impact of the UT antagonist urantide on survival, systemic inflammation, and cardiac function during endotoxic shock.

METHODS

C57Bl/6 mice were intraperitoneally injected with lipopolysaccharide (LPS) and then randomized to be injected either by urantide or NaCl 0.9% 3, 6, and 9 h (H3, H6, H9) after LPS. The effect of urantide on the survival rate, the levels of cytokines in plasma at H6, H9, H12, the expression level of nuclear factor-kappa B (NF-κB-p65) in liver and kidney (at H12), and the cardiac function by trans-thoracic echocardiography from H0 to H9 was evaluated.

RESULTS

Urantide treatment improved survival (88.9% vs. 30% on day 6, P < 0.05). This was associated with changes in cytokine expression: a decrease in IL-6 (2,485 [2,280-2,751] pg/mL vs. 3,330 [3,119-3,680] pg/mL, P < 0.01) at H6, in IL-3 (1.0 [0.40-2.0] pg/mL vs. 5.8 [3.0-7.7] pg/mL, P < 0.01), and IL-1β (651 [491-1,135] pg/mL vs. 1,601 [906-3,010] pg/mL, P < 0.05) at H12 after LPS administration. Urantide decreased the proportion of cytosolic NF-κB-p65 in liver (1.3 [0.9-1.9] vs. 3.2 [2.3-4], P < 0.01) and kidney (0.3 [0.3-0.4] vs. 0.6 [0.5-1.1], P < 0.01). Urantide improved cardiac function (left ventricular fractional shortening: 24.8 [21.5-38.9] vs. 12.0 [8.7-17.6] %, P < 0.01 and cardiac output: 30.3 [25.9-39.8] vs. 15.1 [13.0-16.9] mL/min, P < 0.0001).

CONCLUSION

These results show a beneficial curative role of UT antagonism on cytokine response (especially IL-3), cardiac dysfunction, and survival during endotoxic shock in mice, highlighting a potential new therapeutic target for septic patients.

Neuronal-driven glioma growth requires Gαi1 and Gαi3

Neuroligin-3 (NLGN3) is necessary and sufficient to promote glioma cell growth. The recruitment of Gαi1/3 to the ligand-activated receptor tyrosine kinases (RTKs) is essential for mediating oncogenic signaling.

Methods: Various genetic strategies were utilized to examine the requirement of Gαi1/3 in NLGN3-driven glioma cell growth.

Results: NLGN3-induced Akt-mTORC1 and Erk activation was inhibited by decreasing Gαi1/3 expression. In contrast ectopic Gαi1/3 overexpression enhanced NLGN3-induced signaling. In glioma cells, NLGN3-induced cell growth, proliferation and migration were attenuated by Gαi1/3 depletion with shRNA, but facilitated with Gαi1/3 overexpression. Significantly, Gαi1/3 silencing inhibited orthotopic growth of patient-derived glioma xenografts in mouse brain, whereas forced Gαi1/3-overexpression in primary glioma xenografts significantly enhanced growth. The growth of brain-metastatic human lung cancer cells in mouse brain was largely inhibited with Gαi1/3 silencing. It was however expedited with ectopic Gαi1/3 overexpression. In human glioma Gαi3 upregulation was detected, correlating with poor prognosis.

Conclusion: Gαi1/3 mediation of NLGN3-induced signaling is essential for neuronal-driven glioma growth.

Targeting the Urotensin II/UT G Protein-Coupled Receptor to Counteract Angiogenesis and Mesenchymal Hypoxia/Necrosis in Glioblastoma

Glioblastomas (GBMs) are the most common primary brain tumors characterized by strong invasiveness and angiogenesis. GBM cells and microenvironment secrete angiogenic factors and also express chemoattractant G protein-coupled receptors (GPCRs) to their advantage. We investigated the role of the vasoactive peptide urotensin II (UII) and its receptor UT on GBM angiogenesis and tested potential ligand/therapeutic options based on this system. On glioma patient samples, the expression of UII and UT increased with the grade with marked expression in the vascular and peri-necrotic mesenchymal hypoxic areas being correlated with vascular density. In vitro human UII stimulated human endothelial HUV-EC-C and hCMEC/D3 cell motility and tubulogenesis. In mouse-transplanted Matrigel sponges, mouse (mUII) and human UII markedly stimulated invasion by macrophages, endothelial, and smooth muscle cells. In U87 GBM xenografts expressing UII and UT in the glial and vascular compartments, UII accelerated tumor development, favored hypoxia and necrosis associated with increased proliferation (Ki67), and induced metalloproteinase (MMP)-2 and -9 expression in Nude mice. UII also promoted a “tortuous” vascular collagen-IV expressing network and integrin expression mainly in the vascular compartment. GBM angiogenesis and integrin αvβ3 were confirmed by in vivo^99mTc-RGD tracer imaging and tumoral capture in the non-necrotic area of U87 xenografts in Nude mice. Peptide analogs of UII and UT antagonist were also tested as potential tumor repressor. Urotensin II-related peptide URP inhibited angiogenesis in vitro and failed to attract vascular and inflammatory components in Matrigel in vivo. Interestingly, the UT antagonist/biased ligand urantide and the non-peptide UT antagonist palosuran prevented UII-induced tubulogenesis in vitro and significantly delayed tumor growth in vivo. Urantide drastically prevented endogenous and UII-induced GBM angiogenesis, MMP, and integrin activations, associated with GBM tumoral growth. These findings show that UII induces GBM aggressiveness with necrosis and angiogenesis through integrin activation, a mesenchymal behavior that can be targeted by UT biased ligands/antagonists.

Development of Novel 111-In-Labelled DOTA Urotensin II Analogues for Targeting the UT Receptor Overexpressed in Solid Tumours

Overexpression of G protein-coupled receptors (GPCRs) in tumours is widely used to develop GPCR-targeting radioligands for solid tumour imaging in the context of diagnosis and even treatment. The human vasoactive neuropeptide urotensin II (hUII), which shares structural analogies with somatostatin, interacts with a single high affinity GPCR named UT. High expression of UT has been reported in several types of human solid tumours from lung, gut, prostate, or breast, suggesting that UT is a valuable novel target to design radiolabelled hUII analogues for cancer diagnosis. In this study, two original urotensinergic analogues were first conjugated to a DOTA chelator via an aminohexanoic acid (Ahx) hydrocarbon linker and then -hUII and DOTA-urantide, complexed to the radioactive metal indium isotope to successfully lead to radiolabelled DOTA-Ahx-hUII and DOTA-Ahx-urantide. The 111In-DOTA-hUII in human plasma revealed that only 30% of the radioligand was degraded after a 3-h period. DOTA-hUII and DOTA-urantide exhibited similar binding affinities as native peptides and relayed calcium mobilization in HEK293 cells expressing recombinant human UT. DOTA-hUII, not DOTA-urantide, was able to promote UT internalization in UT-expressing HEK293 cells, thus indicating that radiolabelled 111In-DOTA-hUII would allow sufficient retention of radioactivity within tumour cells or radiolabelled DOTA-urantide may lead to a persistent binding on UT at the plasma membrane. The potential of these radioligands as candidates to target UT was investigated in adenocarcinoma. We showed that hUII stimulated the migration and proliferation of both human lung A549 and colorectal DLD-1 adenocarcinoma cell lines endogenously expressing UT. In vivo intravenous injection of 111In-DOTA-hUII in C57BL/6 mice revealed modest organ signals, with important retention in kidney. 111In-DOTA-hUII or 111In-DOTA-urantide were also injected in nude mice bearing heterotopic xenografts of lung A549 cells or colorectal DLD-1 cells both expressing UT. The observed significant renal uptake and low tumour/muscle ratio (around 2.5) suggest fast tracer clearance from the organism. Together, DOTA-hUII and DOTA-urantide were successfully radiolabelled with 111Indium, the first one functioning as a UT agonist and the second one as a UT-biased ligand/antagonist. To allow tumour-specific targeting and prolong body distribution in preclinical models bearing some solid tumours, these radiolabelled urotensinergic analogues should be optimized for being used as potential molecular tools for diagnosis imaging or even treatment tools.

Association between vasoactive peptide urotensin II in plasma and cerebral vasospasm after aneurysmal subarachnoid hemorrhage: a potential therapeutic target

OBJECTIVE

Cerebral vasospasm (VS) is a severe complication of aneurysmal subarachnoid hemorrhage (SAH). Urotensin II (UII) is a potent vasoactive peptide activating the urotensin (UT) receptor, potentially involved in brain vascular pathologies. The authors hypothesized that UII/UT system antagonism with the UT receptor antagonist/biased ligand urantide may be associated with post-SAH VS. The objectives of this study were 2-fold: 1) to leverage an experimental mouse model of SAH with VS in order to study the effect of urotensinergic system antagonism on neurological outcome, and 2) to investigate the association between plasma UII level and symptomatic VS after SAH in human patients.

METHODS

A mouse model of SAH was used to study the impacts of UII and the UT receptor antagonist/biased ligand urantide on VS and neurological outcome. Then a clinical study was conducted in the setting of a neurosurgical intensive care unit. Plasma UII levels were measured in SAH patients daily for 9 days, starting on the 1st day of hospitalization, and were compared with plasma UII levels in healthy volunteers.

RESULTS

In the mouse model, urantide prevented VS as well as SAH-related fine motor coordination impairment. Seventeen patients with SAH and external ventricular drainage were included in the clinical study. The median plasma UII level was 43 pg/ml (IQR 14-80 pg/ml). There was no significant variation in the daily median plasma UII level (median value for the 17 patients) from day 0 to day 8. The median level of plasma UII during the 9 first days post-SAH was higher in patients with symptomatic VS than in patients without VS (77 pg/ml [IQR 33.5-111.5 pg/ml] vs 37 pg/ml [IQR 21-46 pg/ml], p < 0.05). Concerning daily measures of plasma UII levels in VS, non-VS patients, and healthy volunteers, we found a significant difference between SAH patients with VS (median 66 pg/ml [IQR 30-110 pg/ml]) and SAH patients without VS (27 pg/ml [IQR 15-46 pg/ml], p < 0.001) but no significant difference between VS patients and healthy volunteers (44 pg/ml [IQR 27-51 pg/ml]) or between non-VS patients and healthy volunteers.

CONCLUSIONS

The results of this study suggest that UT receptor antagonism with urantide prevents VS and improves neurological outcome after SAH in mice and that an increase in plasma UII is associated with cerebral VS subsequent to SAH in humans. The causality link between circulating UII and VS after SAH remains to be established, but according to our data the UT receptor is a potential therapeutic target in SAH.

The Autophagy Machinery: A New Player in Chemotactic Cell Migration

Autophagy is a highly conserved self-degradative process that plays a key role in diverse cellular processes such as stress response or differentiation. A growing body of work highlights the direct involvement of autophagy in cell migration and cancer metastasis. Specifically, autophagy has been shown to be involved in modulating cell adhesion dynamics as well as epithelial-to-mesenchymal transition. After providing a general overview of the mechanisms controlling autophagosome biogenesis and cell migration, we discuss how chemotactic G protein-coupled receptors, through the repression of autophagy, may orchestrate membrane trafficking and compartmentation of specific proteins at the cell front in order to support the critical steps of directional migration.

The effects of urotensin II on migration and invasion are mediated by NADPH oxidase-derived reactive oxygen species through the c-Jun N-terminal kinase pathway in human hepatoma cells

AIMS

Urotensin II (UII) is a vasoactive neuropeptide involved in migration and invasion in various cell types. However, the effects of UII on human hepatoma cells still remain unclear. The aim of this study was to investigate the role and mechanism of UII on migration and invasion in human hepatoma cells.

METHODS

Migration was measured by wound healing assays and a Transwell^® methodology, and invasion was analyzed using Matrigel^® invasion chambers. Reactive oxygen species (ROS) levels were detected using a 2', 7'-dichlorofluorescein diacetate probe, and flow cytometry, and protein expression levels were evaluated by western blotting. Cell proliferation and actin polymerization were examined using cell proliferation reagent WST-1 and F-actin immunohistochemistry staining.

RESULTS

Exposure to UII promoted migration and invasion in hepatoma cells compared with that in cells without UII. UII also increased matrix metalloproteinase-2 (MMP2) expression in a time-independent manner. Furthermore, UII markedly enhanced ROS generation and NADPH oxidase subunit expression, and consequently facilitated the phosphorylation of c-Jun N-terminal kinase (JNK). The UT antagonist urantide or the antioxidant/NADPH oxidase inhibitor apocynin decreased UII-induced ROS production. JNK phosphorylation, migration, invasion, and MMP9/2 expression were also reversed by pretreatment with apocynin. Urantide and JNK inhibitor SP600125 abrogated migration, invasion, or MMP9/2 expression in response to UII. UII induced actin polymerization and fascin protein expression, and could be reversed by apocynin and SP600125.

CONCLUSIONS

Exogenous UII induced migration and invasion in hepatoma cells that mainly involved NADPH oxidase-derived ROS through JNK activation. UT played an additional role in regulating hepatoma cells migration and invasion. Thus, our data suggested an important effect of UII in hepatocellular carcinoma metastasis.

The G Protein-Coupled Receptor UT of the Neuropeptide Urotensin II Displays Structural and Functional Chemokine Features

The urotensinergic system was previously considered as being linked to numerous physiopathological states, including atherosclerosis, heart failure, hypertension, pre-eclampsia, diabetes, renal disease, as well as brain vascular lesions. Thus, it turns out that the actions of the urotensin II (UII)/G protein-coupled receptor UT system in animal models are currently not predictive enough in regard to their effects in human clinical trials and that UII analogs, established to target UT, were not as beneficial as expected in pathological situations. Thus, many questions remain regarding the overall signaling profiles of UT leading to complex involvement in cardiovascular and inflammatory responses as well as cancer. We address the potential UT chemotactic structural and functional definition under an evolutionary angle, by the existence of a common conserved structural feature among chemokine receptorsopioïdergic receptors and UT, i.e., a specific proline position in the transmembrane domain-2 TM2 (P2.58) likely responsible for a kink helical structure that would play a key role in chemokine functions. Even if the last decade was devoted to the elucidation of the cardiovascular control by the urotensinergic system, we also attempt here to discuss the role of UII on inflammation and migration, likely providing a peptide chemokine status for UII. Indeed, our recent work established that activation of UT by a gradient concentration of UII recruits Gαi/o and Gα13 couplings in a spatiotemporal way, controlling key signaling events leading to chemotaxis. We think that this new vision of the urotensinergic system should help considering UT as a chemotactic therapeutic target in pathological situations involving cell chemoattraction.

Age-Related Reduction of Contractile Responses to Urotensin II Is Seen in Aortas from Wistar Rats but Not from Type 2 Diabetic Goto-Kakizaki Rats

Vascular dysfunction is a common finding in type 2 diabetes, although the response to urotensin II (UII), a potent vasoconstrictor peptide, remains unclear. We investigated whether a UII-induced contraction was increased in the aortas from type 2 diabetic Goto-Kakizaki (GK) rats at the chronic stage. At 36 or 37 weeks of age (older group), a UII-induced contraction was seen in GK rats and was reduced by a Rho kinase inhibitor or urotensin receptor (UT) antagonist, whereas UII failed to induce a contraction in aortas from age-matched Wistar rats. In UII-stimulated aortas, the expression of Rho kinases, Rho A, and phosphorylated myosin phosphatase target subunit 1 did not change between the two groups; however, phosphorylation of extracellular-regulated kinase 1/2 and p38 mitogen-activated protein kinase (MAPK) was greater in GK than in Wistar rats. Compared to intact aortas, UII-induced contractions were slightly, but not significantly, increased by endothelial denudation of the aortas of Wistar rats at 24 weeks of age. At 6 weeks of age (young group), the UII-induced contractions were seen in GK and Wistar groups. The total expression and the membrane-to-cytosol ratio of the UT protein slightly decreased in Wistar aortas with aging but not in GK aortas. These results demonstrate that the UII-induced contraction gradually decreased with aging in Wistar rats and was preserved in type 2 diabetes. Although alterations of UII-induced contractions during aging and type 2 diabetes may be associated with kinase activities (MAPKs or Rho kinase) or receptor profiles, further investigations are necessary to clarify the mechanisms.

Chemotactic G protein-coupled receptors control cell migration by repressing autophagosome biogenesis

Chemotactic migration is a fundamental behavior of cells and its regulation is particularly relevant in physiological processes such as organogenesis and angiogenesis, as well as in pathological processes such as tumor metastasis. The majority of chemotactic stimuli activate cell surface receptors that belong to the G protein-coupled receptor (GPCR) superfamily. Although the autophagy machinery has been shown to play a role in cell migration, its mode of regulation by chemotactic GPCRs remains largely unexplored. We found that ligand-induced activation of 2 chemotactic GPCRs, the chemokine receptor CXCR4 and the urotensin 2 receptor UTS2R, triggers a marked reduction in the biogenesis of autophagosomes, in both HEK-293 and U87 glioblastoma cells. Chemotactic GPCRs exert their anti-autophagic effects through the activation of CAPNs, which prevent the formation of pre-autophagosomal vesicles from the plasma membrane. We further demonstrated that CXCR4- or UTS2R-induced inhibition of autophagy favors the formation of adhesion complexes to the extracellular matrix and is required for chemotactic migration. Altogether, our data reveal a new link between GPCR signaling and the autophagy machinery, and may help to envisage therapeutic strategies in pathological processes such as cancer cell invasion.