The role of ACKR3 in breast, lung, and brain cancer

Recent reports regarding the significance of chemokine receptors in disease have put a spotlight on atypical chemokine receptor 3 (ACKR3). This atypical chemokine receptor is overexpressed in numerous cancer types and has been involved in the modulation of tumor cell proliferation and migration, tumor angiogenesis, or resistance to drugs, thus contributing to cancer progression and metastasis occurrence. Here, we focus on the clinical significance and potential mechanisms underlying the pathologic role of ACKR3 in breast, lung, and brain cancer and discuss its possible relevance as a prognostic factor and potential therapeutic target in these contexts.European Union H2020-MSCA Program [Grant Agreement 64183], ONCORNET to P.M., M.J.S., and F.M.; Ministerio de Economía, Industria y Competitividad of Spain [Grant SAF2017-84125-R] to F.M.; CIBERCV-Instituto de Salud Carlos III, Spain [Grant CB16/11/00278] to F.M.; cofunded with European FEDER contribution, Comunidad de Madrid [B2017/BMD-3671-INFLAMUNE] to F.M.; Fundación Ramón Areces to F.M.; Portuguese Foundation for Science and Technology [Grant SFRH/BD/136574/2018] to M.N.; Netherlands Organization for Scientific Research NWO: Vici [Grant 016.140.657] to M.J.S.; and grants from CNRS, INSERM, Université de Montpellier and Fondation pour la Recherche Médical

Calpains mediate isoproterenol-induced hypertrophy through modulation of GRK2

Inhibition of the Ca -dependent proteases calpains attenuates post-infarction remodeling and heart failure. Recent data suggest that calpain activity is elevated in non-ischemic cardiomyopathies and that upregulation of the key cardiac G-protein-coupled receptor kinase 2 (GRK2) signaling hub promotes cardiac hypertrophy. However, the functional interactions between calpains and GRK2 in this context have not been explored. We hypothesized that calpain modulates GRK2 levels in myocardial hypertrophy of non-ischemic cause, and analyzed the mechanisms involved and the potential therapeutic benefit of inhibiting calpain activity in this situation. The oral calpain inhibitor SNJ-1945 was administered daily to male Sprague–Dawley rats or wild-type and hemizygous GRK2 mice treated with 5 mg/Kg/day isoproterenol intraperitoneally for 1 week. In isoproterenol-treated animals, calpains 1 and 2 were overexpressed in myocardium and correlated with increased calpain activity and ventricular hypertrophy. Oral co-administration of SNJ-1945 attenuated calpain activation and reduced heart hypertrophy as assessed using morphological and biochemical markers. Calpain activation induced by isoproterenol increased GRK2 protein levels, while genetic downregulation of GRK2 expression prevented isoproterenol-mediated hypertrophy independently of calpain inhibition. GRK2 upregulation was associated to calpain-dependent degradation of the GRK2 ubiquitin ligase MDM2 and to enhanced NF-κB-dependent GRK2 gene expression in correlation with calpain-mediated IĸB proteolysis. These results demonstrate that calpain mediates isoproterenol-induced myocardial hypertrophy by modulating GRK2 protein content through mechanisms involving the control of GRK2 stability and expression. Sustained calpain inhibition attenuates isoproterenol-induced myocardial hypertrophy and could be an effective therapeutic strategy to limit ventricular remodeling of non-ischemic origin.Instituto de Salud Carlos III, Spain [PI-16/00232; RETICS-RIC-RD12/0042/0021 to D.G.D., cofunded with European Regional Development Fund-FEDER contribution], by Ministerio de Economía; Industria y Competitividad (MINECO) of Spain [SAF2017-84125-R to F.M.]; by CIBERCVInstituto de Salud Carlos III, Spain [CB16/11/00479 to D.G.D. and CB16/11/00278 to F.M, co-funded with European Regional Development Fund-FEDER contribution], and Programa de Actividades en Biomedicina de la Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE to F.M. We also acknowledge institutional support to the CBMSO from Fundación Ramón Arece

CXCR4/AckR3 phosphorylation and recruitment of interacting proteins: Key mechanisms regulating their functional status

The C-X-C motif chemokine receptor type 4 (CXCR4) and the atypical chemokine receptor 3 (ACKR3/CXCR7) are class A G protein-coupled receptors (GPCRs). Accumulating evidence indicates that GPCR subcellular localization, trafficking, transduction properties, and ultimately their pathophysiological functions are regulated by both interacting proteins and post-translational modifications. This has encouraged the development of novel techniques to characterize the GPCR interactome and to identify residues subjected to post-translational modifications, with a special focus on phosphorylation. This review first describes state-of-the-art methods for the identification of GPCR-interacting proteins and GPCR phosphorylated sites. In addition, we provide an overview of the current knowledge of CXCR4 and ACKR3 post-translational modifications and an exhaustive list of previously identified CXCR4- or ACKR3-interacting proteins. We then describe studies highlighting the importance of the reciprocal influence of CXCR4/ACKR3 interactomes and phosphorylation states. We also discuss their impact on the functional status of each receptor. These studies suggest that deeper knowledge of the CXCR4/ACKR3 interactomes along with their phosphorylation and ubiquitination status would shed new light on their regulation and pathophysiological functions.European Union’s Horizon2020 MSCA European Union’s Horizon2020 MSCA Program [Grant agreement 641833 (ONCORNET)]; A.F. and P.M. are also supported by CNRS, INSERM, Université de Montpellier and Fondation pour la Recherche Médicale (FRM); F.M. laboratory is also supported by grants from Ministerio de Economía; Industria y Competitividad (MINECO) of Spain [Grant SAF2017-84125-R]; CIBERCV-Instituto de Salud Carlos III, Spain [Grant CB16/11/00278] to F.M., cofunded with European FEDER contribution); Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE; and Fundación Ramón Areces. Program [Grant agreement 641833 (ONCORNET)]; A.F. and P.M. are also supported by CNRS, INSERM, Université de Montpellier and Fondation pour la Recherche Médicale (FRM); F.M. laboratory is also supported by grants from Ministerio de Economía; Industria y Competitividad (MINECO) of Spain [Grant SAF2017-84125-R]; CIBERCV-Instituto de Salud Carlos III, Spain [Grant CB16/11/00278] to F.M., cofunded with European FEDER contribution); Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE; and Fundación Ramón Areces

Autophagy mediates hepatic GRK2 degradation to facilitate glucagon-induced metabolic adaptation to fasting

The liver plays a key role during fasting to maintain energy homeostasis and euglycemia via metabolic processes mainly orchestrated by the insulin/glucagon ratio. We report here that fasting or calorie restriction protocols in C57BL6 mice promote a marked decrease in the hepatic protein levels of G protein-coupled receptor kinase 2 (GRK2), an important negative modulator of both G protein-coupled receptors (GPCRs) and insulin signaling. Such downregulation of GRK2 levels is liver-specific and can be rapidly reversed by refeeding. We find that autophagy, and not the proteasome, represents the main mechanism implicated in fasting-induced GRK2 degradation in the liver in vivo. Reducing GRK2 levels in murine primary hepatocytes facilitates glucagon-induced glucose production and enhances the expression of the key gluconeogenic enzyme Pck1. Conversely, preventing full downregulation of hepatic GRK2 during fasting using adenovirus-driven overexpression of this kinase in the liver leads to glycogen accumulation, decreased glycemia, and hampered glucagon-induced gluconeogenesis, thus preventing a proper and complete adaptation to nutrient deprivation. Overall, our data indicate that physiological fasting-induced downregulation of GRK2 in the liver is key for allowing complete glucagon-mediated responses and efficient metabolic adaptation to fasting in vivo.Ministerio de Economia y Competitividad (MINECO/FEDER), Spain (grant SAF2017-84125-R to F.M. and C. M.); CIBER de Enfermedades Cardiovasculares (CIBERCV). Instituto de Salud Carlos III, Spain (grant CB16/11/00278 to FM, co-funded with European FEDER contribution); European Foundation for the Study of Diabetes (EFSD) Novo Nordisk Partnership for Diabetes Research in Europe Grant (to FM); NIH R01 DK089883 grant to P.P. and Programa de Actividades en Biomedicina de la Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE to F.M and CBMSO from Fundacion Ramon Areces and Fundacion Banco de Santande

Myeloid GRK2 Regulates Obesity-Induced Endothelial Dysfunction by Modulating Inflammatory Responses in Perivascular Adipose Tissue

Perivascular adipose tissue (PVAT) is increasingly being regarded as an important endocrine organ that directly impacts vessel function, structure, and contractility in obesity-associated diseases. We uncover here a role for myeloid G protein-coupled receptor kinase 2 (GRK2) in the modulation of PVAT-dependent vasodilation responses. GRK2 expression positively correlates with myeloid- (CD68) and lymphoid-specific (CD3, CD4, and CD8) markers and with leptin in PVAT from patients with abdominal aortic aneurysms. Using mice hemizygous for GRK2 in the myeloid lineage (LysM-GRK2+/), we found that GRK2 deficiency in myeloid cells allows animals to preserve the endothelium-dependent acetylcholine or insulin-induced relaxation, which is otherwise impaired by PVAT, in arteries of animals fed a high fat diet (HFD). Downregulation of GRK2 in myeloid cells attenuates HFD-dependent infiltration of macrophages and T lymphocytes in PVAT, as well as the induction of tumor necrosis factor- (TNF) and NADPH oxidase (Nox)1 expression, whereas blocking TNF or Nox pathways by pharmacological means can rescue the impaired vasodilator responses to insulin in arteries with PVAT from HFD-fed animals. Our results suggest that myeloid GRK2 could be a potential therapeutic target in the development of endothelial dysfunction induced by PVAT in the context of obesityMinisterio de Economía y Competitividad (MINECO/FEDER), Spain (grant SAF2017-84125-R to F.M.J. and C.M.; SAF2016-80305P to M.S. and A.M.B.); CIBER de Enfermedades Cardiovasculares (CIBERCV); Instituto de Salud Carlos III, Spain (grant CB16/11/00278 to F.M.J. and CB16/11/00286 to M.S.); European Foundation for the Study of Diabetes (EFSD) Novo Nordisk Partnership for Diabetes Research in Europe Grant (to F.M.J.); and Programa de Actividades en Biomedicina de la Comunidad de Madrid—FEDER-a way to build Europe B2017/BMD-3671-INFLAMUNE to F.M.J. and B2017/BMD-3676-AORTASANA to M.S. M.G.-A. was supported by a FPI-UAM fellowship, R.R.-D. by a Juan de la Cierva contract (IJCI-2017-31399). We appreciate the help of the CBMSO Facilities, in particular Animal Care. We also acknowledge the institutional support to the CBMSO.from Funcación Ramón Arece