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Cai L, Fan G, Wang F, Liu S, Li T, Cong X, Chun J, Chen X. Protective Role for LPA 3 in Cardiac Hypertrophy Induced by Myocardial Infarction but Not by Isoproterenol. Front Physiol 2017; 8:356. [PMID: 28611684 PMCID: PMC5447740 DOI: 10.3389/fphys.2017.00356] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 05/15/2017] [Indexed: 01/04/2023] Open
Abstract
Background: We previously reported that lysophosphatidic acid (LPA) promoted cardiomyocyte hypertrophy in vitro via one of its G protein-coupled receptor subtypes, LPA3. In this study, we examined the role of LPA3 in cardiac hypertrophy induced by isoproterenol (ISO) and myocardial infarction. Methods:In vitro, neonatal rat cardiomyocytes (NRCMs) were subjected to LPA3 knocked-down, or pretreated with a β-adrenergic receptor (β-AR) antagonist (propranolol) before LPA/ISO treatment. Cardiomyocyte size and hypertrophic gene (ANP, BNP) mRNA levels were determined. In vivo, [Formula: see text] and wild-type mice were implanted subcutaneously with an osmotic mini-pump containing ISO or vehicle for 2 weeks; echocardiography was performed to determine the heart weight/body weight ratio, cardiomyocyte cross-sectional area, and level of ANP mRNA expression. [Formula: see text] and wild-type mice were subjected to permanent coronary artery ligation or sham surgery for 4 weeks; cardiac function, including the degree of hypertrophy and infarction size, was determined. Results:In vitro, we found that knocked-down LPA3 in NRCMs did not attenuate ISO-induced hypertrophy, and propranolol was unable to abolish LPA-induced hypertrophy. In vivo, chronic ISO infusion caused cardiac hypertrophy in wild-type mice, while hypertrophic responses to ISO infusion were not attenuated in [Formula: see text] mice. However, in a myocardial infarction (MI) model, [Formula: see text] mice exhibited reduced cardiac hypertrophy compared to wild-type mice at 4 weeks post-MI, which was associated with reduced cardiac function and increased infarct size. Conclusions: Our data show that LPA3 appears to play a protective role in myocardial hypertrophy post-MI, but does not appear to be involved in the hypertrophy that occurs in response to β-AR stimulation in vivo and in vitro. These results implicate LPA-LPA3 lipid signaling in cardiac hypertrophy occurring after pathological insults like MI, which presents a new variable in β-AR-independent hypertrophy. Thus, modulation of LPA3 signaling might represent a new strategy for preventing the stressed myocardium from ischemia injury.
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Gaire BP, Lee CH, Sapkota A, Lee SY, Chun J, Cho HJ, Nam TG, Choi JW. Identification of Sphingosine 1-Phosphate Receptor Subtype 1 (S1P 1) as a Pathogenic Factor in Transient Focal Cerebral Ischemia. Mol Neurobiol 2017; 55:2320-2332. [PMID: 28343295 DOI: 10.1007/s12035-017-0468-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 02/23/2017] [Indexed: 01/06/2023]
Abstract
Medically relevant roles of receptor-mediated sphingosine 1-phosphate (S1P) signaling have become a successful or promising target for multiple sclerosis or cerebral ischemia. Animal-based proof-of-concept validation for the latter is particularly through the neuroprotective efficacy of FTY720, a non-selective S1P receptor modulator, presumably via activation of S1P1. In spite of a clear link between S1P signaling and cerebral ischemia, it remains unknown whether the role of S1P1 is pathogenic or neuroprotective. Here, we investigated the involvement of S1P1 along with its role in cerebral ischemia using a transient middle cerebral artery occlusion ("tMCAO") model. Brain damage following tMCAO, as assessed by brain infarction, neurological deficit score, and neural cell death, was reduced by oral administration of AUY954, a selective S1P1 modulator as a functional antagonist, in a therapeutic paradigm, indicating that S1P1 is a pathogenic mediator rather than a neuroprotective mediator. This pathogenic role of S1P1 in cerebral ischemia was reaffirmed because tMCAO-induced brain damage was reduced by genetic knockdown with an intracerebroventricular microinjection of S1P1 shRNA lentivirus into the brain. Genetic knockdown of S1P1 or AUY954 exposure reduced microglial activation, as assessed by reduction in the number of activated microglia and reversed morphology from amoeboid to ramified, and microglial proliferation in ischemic brain. Its role in microglial activation was recapitulated in lipopolysaccharide-stimulated primary mouse microglia, in which the mRNA expression level of TNF-α and IL-1β, well-known markers for microglial activation, was reduced in microglia transfected with S1P1 siRNA. These data suggest that the pathogenic role of S1P1 is associated with microglial activation in ischemic brain. Additionally, the pathogenic role of S1P1 in cerebral ischemia appears to be associated with the blood-brain barrier disruption and brain-derived neurotrophic factor (BDNF) downregulation. Overall, findings from the current study clearly identify S1P1 signaling as a pathogenic factor in transient focal cerebral ischemia, further implicating S1P1 antagonists including functional antagonists as plausible therapeutic agents for human stroke.
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Schnabel F, Schwartz S, Hochman T, Chun J, Goldberg J. Abstract P5-16-26: National trends in neoadjuvant therapy for breast cancer. Cancer Res 2017. [DOI: 10.1158/1538-7445.sabcs16-p5-16-26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Purpose:Neoadjuvant therapy has been widely integrated in the treatment of locally advanced breast cancer. Over time, this strategy has been extended to include patients with earlier stage disease to allow for assessment of in vivo response to treatment. The aim of this study was to describe the national trends in neoadjuvant therapy for all invasive breast cancers with a particular focus on triple negative disease and HER2 status.
Methods: The National Cancer Database (NCDB), an oncology outcomes database that collects data from more than 1500 Commission on Cancer (CoC) accredited cancer programs, was queried for all women diagnosed with invasive breast cancer from 2006-2013. Patients with unknown systemic therapy sequence were excluded. Women were classified by whether or not they received neoadjuvant systemic, chemo and/or endocrine, therapy.
Results: We identified 1,221,976 cases that were eligible for this analysis. Of these, 29.7% were HER2 negative, 18.4% were classified as triple negative, and 8.9% received neoadjuvant systemic therapy. The percentage of patients receiving neoadjuvant therapy increased from 7.5% in 2006 to 9.8% in 2012 with a slight decrease to 9.5% in 2013. This increase in the use of neoadjuvant therapy over the time period was statistically significant (p<0.0001). There was a small increase in the percent of patients with HER2 positive status who received neoadjuvant therapy, from 5.7% in 2006 to 6.5% in 2013. During this time period, there was a 9% increase in the percent of triple negative patients who received neoadjuvant therapy (13.1% in 2016 to 22.1% in 2013).
Number and percent of patients who received/did not receive neoadjuvant therapy by year2006 (N=136117)2007 (N=143033)2008 (N=148888)2009 (N=154713)2010 (N=154040)2011 (N=162333)2012 (N=163395)2013 (N=159457)No Neoadjuvant Therapy | 125908 (92.5)131559 (91.98)136593 (91.74)141364 (91.37)139459 (90.53)146500 (90.25)147401 (90.21)144306 (90.5)Neoadjuvant Therapy | 10209 (7.5)11474 (8.02)12295 (8.26)13349 (8.63)14581 (9.47)15833 (9.75)15994 (9.79)15151 (9.5)
Conclusions: Over the time period from 2006-2013, there has been an apparent increase in the percentage of patients who received neoadjuvant therapy. This trend is accompanied by increases in the percentage of TNBC patients and in Her2 positive patients who received neoadjuvant therapy. Other factors and the joint effects of these factors on the observed increase in the use of neoadjuvant therapy are under evaluation to elucidate the basis for this observation in the NCDB data.
Citation Format: Schnabel F, Schwartz S, Hochman T, Chun J, Goldberg J. National trends in neoadjuvant therapy for breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-26.
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Dancs PT, Ruisanchez É, Balogh A, Panta CR, Miklós Z, Nüsing RM, Aoki J, Chun J, Offermanns S, Tigyi G, Benyó Z. LPA 1 receptor-mediated thromboxane A 2 release is responsible for lysophosphatidic acid-induced vascular smooth muscle contraction. FASEB J 2017; 31:1547-1555. [PMID: 28069828 DOI: 10.1096/fj.201600735r] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 12/19/2016] [Indexed: 02/05/2023]
Abstract
Lysophosphatidic acid (LPA) has been recognized recently as an endothelium-dependent vasodilator, but several lines of evidence indicate that it may also stimulate vascular smooth muscle cells (VSMCs), thereby contributing to vasoregulation and remodeling. In the present study, mRNA expression of all 6 LPA receptor genes was detected in murine aortic VSMCs, with the highest levels of LPA1, LPA2, LPA4, and LPA6 In endothelium-denuded thoracic aorta (TA) and abdominal aorta (AA) segments, 1-oleoyl-LPA and the LPA1-3 agonist VPC31143 induced dose-dependent vasoconstriction. VPC31143-induced AA contraction was sensitive to pertussis toxin (PTX), the LPA1&3 antagonist Ki16425, and genetic deletion of LPA1 but not that of LPA2 or inhibition of LPA3, by diacylglycerol pyrophosphate. Surprisingly, vasoconstriction was also diminished in vessels lacking cyclooxygenase-1 [COX1 knockout (KO)] or the thromboxane prostanoid (TP) receptor (TP KO). VPC31143 increased thromboxane A2 (TXA2) release from TA of wild-type, TP-KO, and LPA2-KO mice but not from LPA1-KO or COX1-KO mice, and PTX blocked this effect. Our findings indicate that LPA causes vasoconstriction in VSMCs, mediated by LPA1-, Gi-, and COX1-dependent autocrine/paracrine TXA2 release and consequent TP activation. We propose that this new-found interaction between the LPA/LPA1 and TXA2/TP pathways plays significant roles in vasoregulation, hemostasis, thrombosis, and vascular remodeling.-Dancs, P. T., Ruisanchez, E., Balogh, A., Panta, C. R., Miklós, Z., Nüsing, R. M., Aoki, J., Chun, J., Offermanns, S., Tigyi, G., Benyó, Z. LPA1 receptor-mediated thromboxane A2 release is responsible for lysophosphatidic acid-induced vascular smooth muscle contraction.
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Yung BS, Brand CS, Xiang SY, Gray CBB, Means CK, Rosen H, Chun J, Purcell NH, Brown JH, Miyamoto S. Selective coupling of the S1P 3 receptor subtype to S1P-mediated RhoA activation and cardioprotection. J Mol Cell Cardiol 2016; 103:1-10. [PMID: 28017639 PMCID: PMC5410967 DOI: 10.1016/j.yjmcc.2016.12.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 12/16/2016] [Accepted: 12/19/2016] [Indexed: 01/17/2023]
Abstract
Sphingosine-1-phosphate (S1P), a bioactive lysophospholipid, is generated and released at sites of tissue injury in the heart and can act on S1P1, S1P2, and S1P3 receptor subtypes to affect cardiovascular responses. We established that S1P causes little phosphoinositide hydrolysis and does not induce hypertrophy indicating that it does not cause receptor coupling to Gq. We previously demonstrated that S1P confers cardioprotection against ischemia/reperfusion by activating RhoA and its downstream effector PKD. The S1P receptor subtypes and G proteins that regulate RhoA activation and downstream responses in the heart have not been determined. Using siRNA or pertussis toxin to inhibit different G proteins in NRVMs we established that S1P regulates RhoA activation through Gα13 but not Gα12, Gαq, or Gαi. Knockdown of the three major S1P receptors using siRNA demonstrated a requirement for S1P3 in RhoA activation and subsequent phosphorylation of PKD, and this was confirmed in studies using isolated hearts from S1P3 knockout (KO) mice. S1P treatment reduced infarct size induced by ischemia/reperfusion in Langendorff perfused wild-type (WT) hearts and this protection was abolished in the S1P3 KO mouse heart. CYM-51736, an S1P3-specific agonist, also decreased infarct size after ischemia/reperfusion to a degree similar to that achieved by S1P. The finding that S1P3 receptor- and Gα13-mediated RhoA activation is responsible for protection against ischemia/reperfusion suggests that selective targeting of S1P3 receptors could provide therapeutic benefits in ischemic heart disease.
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Sakai N, Chun J, Duffield JS, Lagares D, Wada T, Luster AD, Tager AM. Lysophosphatidic acid signaling through its receptor initiates profibrotic epithelial cell fibroblast communication mediated by epithelial cell derived connective tissue growth factor. Kidney Int 2016; 91:628-641. [PMID: 27927603 DOI: 10.1016/j.kint.2016.09.030] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 08/22/2016] [Accepted: 09/15/2016] [Indexed: 02/06/2023]
Abstract
The expansion of the fibroblast pool is a critical step in organ fibrosis, but the mechanisms driving expansion remain to be fully clarified. We previously showed that lysophosphatidic acid (LPA) signaling through its receptor LPA1 expressed on fibroblasts directly induces the recruitment of these cells. Here we tested whether LPA-LPA1 signaling drives fibroblast proliferation and activation during the development of renal fibrosis. LPA1-deficient (LPA1-/-) or -sufficient (LPA1+/+) mice were crossed to mice with green fluorescent protein expression (GFP) driven by the type I procollagen promoter (Col-GFP) to identify fibroblasts. Unilateral ureteral obstruction-induced increases in renal collagen were significantly, though not completely, attenuated in LPA1-/-Col-GFP mice, as were the accumulations of both fibroblasts and myofibroblasts. Connective tissue growth factor was detected mainly in tubular epithelial cells, and its levels were suppressed in LPA1-/-Col-GFP mice. LPA-LPA1 signaling directly induced connective tissue growth factor expression in primary proximal tubular epithelial cells, through a myocardin-related transcription factor-serum response factor pathway. Proximal tubular epithelial cell-derived connective tissue growth factor mediated renal fibroblast proliferation and myofibroblast differentiation. Administration of an inhibitor of myocardin-related transcription factor/serum response factor suppressed obstruction-induced renal fibrosis. Thus, targeting LPA-LPA1 signaling and/or myocardin-related transcription factor/serum response factor-induced transcription could be promising therapeutic strategies for renal fibrosis.
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Gazit SL, Mariko B, Thérond P, Decouture B, Xiong Y, Couty L, Bonnin P, Baudrie V, Le Gall SM, Dizier B, Zoghdani N, Ransinan J, Hamilton JR, Gaussem P, Tharaux PL, Chun J, Coughlin SR, Bachelot-Loza C, Hla T, Ho-Tin-Noé B, Camerer E. Platelet and Erythrocyte Sources of S1P Are Redundant for Vascular Development and Homeostasis, but Both Rendered Essential After Plasma S1P Depletion in Anaphylactic Shock. Circ Res 2016; 119:e110-26. [PMID: 27582371 DOI: 10.1161/circresaha.116.308929] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 08/30/2016] [Indexed: 11/16/2022]
Abstract
RATIONALE Sphingosine-1-phosphate (S1P) signaling is essential for vascular development and postnatal vascular homeostasis. The relative importance of S1P sources sustaining these processes remains unclear. OBJECTIVE To address the level of redundancy in bioactive S1P provision to the developing and mature vasculature. METHODS AND RESULTS S1P production was selectively impaired in mouse platelets, erythrocytes, endothelium, or smooth muscle cells by targeted deletion of genes encoding sphingosine kinases -1 and -2. S1P deficiency impaired aggregation and spreading of washed platelets and profoundly reduced their capacity to promote endothelial barrier function ex vivo. However, and in contrast to recent reports, neither platelets nor any other source of S1P was essential for vascular development, vascular integrity, or hemostasis/thrombosis. Yet rapid and profound depletion of plasma S1P during systemic anaphylaxis rendered both platelet- and erythrocyte-derived S1P essential for survival, with a contribution from blood endothelium observed only in the absence of circulating sources. Recovery was sensitive to aspirin in mice with but not without platelet S1P, suggesting that platelet activation and stimulus-response coupling is needed. S1P deficiency aggravated vasoplegia in this model, arguing a vital role for S1P in maintaining vascular resistance during recovery from circulatory shock. Accordingly, the S1P2 receptor mediated most of the survival benefit of S1P, whereas the endothelial S1P1 receptor was dispensable for survival despite its importance for maintaining vascular integrity. CONCLUSIONS Although source redundancy normally secures essential S1P signaling in developing and mature blood vessels, profound depletion of plasma S1P renders both erythrocyte and platelet S1P pools necessary for recovery and high basal plasma S1P levels protective during anaphylactic shock.
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Lake BB, Ai R, Kaeser GE, Salathia NS, Yung YC, Liu R, Wildberg A, Gao D, Fung HL, Chen S, Vijayaraghavan R, Wong J, Chen A, Sheng X, Kaper F, Shen R, Ronaghi M, Fan JB, Wang W, Chun J, Zhang K. Neuronal subtypes and diversity revealed by single-nucleus RNA sequencing of the human brain. Science 2016; 352:1586-90. [PMID: 27339989 DOI: 10.1126/science.aaf1204] [Citation(s) in RCA: 590] [Impact Index Per Article: 73.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 05/19/2016] [Indexed: 12/19/2022]
Abstract
The human brain has enormously complex cellular diversity and connectivities fundamental to our neural functions, yet difficulties in interrogating individual neurons has impeded understanding of the underlying transcriptional landscape. We developed a scalable approach to sequence and quantify RNA molecules in isolated neuronal nuclei from a postmortem brain, generating 3227 sets of single-neuron data from six distinct regions of the cerebral cortex. Using an iterative clustering and classification approach, we identified 16 neuronal subtypes that were further annotated on the basis of known markers and cortical cytoarchitecture. These data demonstrate a robust and scalable method for identifying and categorizing single nuclear transcriptomes, revealing shared genes sufficient to distinguish previously unknown and orthologous neuronal subtypes as well as regional identity and transcriptomic heterogeneity within the human brain.
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Lai MKP, Chew WS, Torta F, Rao A, Harris GL, Chun J, Herr DR. Biological Effects of Naturally Occurring Sphingolipids, Uncommon Variants, and Their Analogs. Neuromolecular Med 2016; 18:396-414. [DOI: 10.1007/s12017-016-8424-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 06/30/2016] [Indexed: 01/09/2023]
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Keul P, van Borren MMGJ, Ghanem A, Müller FU, Baartscheer A, Verkerk AO, Stümpel F, Schulte JS, Hamdani N, Linke WA, van Loenen P, Matus M, Schmitz W, Stypmann J, Tiemann K, Ravesloot JH, Alewijnse AE, Hermann S, Spijkers LJA, Hiller KH, Herr D, Heusch G, Schäfers M, Peters SLM, Chun J, Levkau B. Sphingosine-1-Phosphate Receptor 1 Regulates Cardiac Function by Modulating Ca2+ Sensitivity and Na+/H+ Exchange and Mediates Protection by Ischemic Preconditioning. J Am Heart Assoc 2016; 5:JAHA.116.003393. [PMID: 27207969 PMCID: PMC4889204 DOI: 10.1161/jaha.116.003393] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Background Sphingosine‐1‐phosphate plays vital roles in cardiomyocyte physiology, myocardial ischemia–reperfusion injury, and ischemic preconditioning. The function of the cardiomyocyte sphingosine‐1‐phosphate receptor 1 (S1P1) in vivo is unknown. Methods and Results Cardiomyocyte‐restricted deletion of S1P1 in mice (S1P1αMHCCre) resulted in progressive cardiomyopathy, compromised response to dobutamine, and premature death. Isolated cardiomyocytes from S1P1αMHCCre mice revealed reduced diastolic and systolic Ca2+ concentrations that were secondary to reduced intracellular Na+ and caused by suppressed activity of the sarcolemmal Na+/H+ exchanger NHE‐1 in the absence of S1P1. This scenario was successfully reproduced in wild‐type cardiomyocytes by pharmacological inhibition of S1P1 or sphingosine kinases. Furthermore, Sarcomere shortening of S1P1αMHCCre cardiomyocytes was intact, but sarcomere relaxation was attenuated and Ca2+ sensitivity increased, respectively. This went along with reduced phosphorylation of regulatory myofilament proteins such as myosin light chain 2, myosin‐binding protein C, and troponin I. In addition, S1P1 mediated the inhibitory effect of exogenous sphingosine‐1‐phosphate on β‐adrenergic–induced cardiomyocyte contractility by inhibiting the adenylate cyclase. Furthermore, ischemic precondtioning was abolished in S1P1αMHCCre mice and was accompanied by defective Akt activation during preconditioning. Conclusions Tonic S1P1 signaling by endogenous sphingosine‐1‐phosphate contributes to intracellular Ca2+ homeostasis by maintaining basal NHE‐1 activity and controls simultaneously myofibril Ca2+ sensitivity through its inhibitory effect on adenylate cyclase. Cardioprotection by ischemic precondtioning depends on intact S1P1 signaling. These key findings on S1P1 functions in cardiac physiology may offer novel therapeutic approaches to cardiac diseases.
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Kitada Y, Kajita K, Taguchi K, Mori I, Yamauchi M, Ikeda T, Kawashima M, Asano M, Kajita T, Ishizuka T, Banno Y, Kojima I, Chun J, Kamata S, Ishii I, Morita H. Blockade of Sphingosine 1-Phosphate Receptor 2 Signaling Attenuates High-Fat Diet-Induced Adipocyte Hypertrophy and Systemic Glucose Intolerance in Mice. Endocrinology 2016; 157:1839-51. [PMID: 26943364 PMCID: PMC4870879 DOI: 10.1210/en.2015-1768] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Sphingosine 1-phosphate (S1P) is known to regulate insulin resistance in hepatocytes, skeletal muscle cells, and pancreatic β-cells. Among its 5 cognate receptors (S1pr1-S1pr5), S1P seems to counteract insulin signaling and confer insulin resistance via S1pr2 in these cells. S1P may also regulate insulin resistance in adipocytes, but the S1pr subtype(s) involved remains unknown. Here, we investigated systemic glucose/insulin tolerance and phenotypes of epididymal adipocytes in high-fat diet (HFD)-fed wild-type and S1pr2-deficient (S1pr2(-/-)) mice. Adult S1pr2(-/-) mice displayed smaller body/epididymal fat tissue weights, but the differences became negligible after 4 weeks with HFD. However, HFD-fed S1pr2(-/-) mice displayed better scores in glucose/insulin tolerance tests and had smaller epididymal adipocytes that expressed higher levels of proliferating cell nuclear antigen than wild-type mice. Next, proliferation/differentiation of 3T3-L1 and 3T3-F442A preadipocytes were examined in the presence of various S1pr antagonists: JTE-013 (S1pr2 antagonist), VPC-23019 (S1pr1/S1pr3 antagonist), and CYM-50358 (S1pr4 antagonist). S1P or JTE-013 treatment of 3T3-L1 preadipocytes potently activated their proliferation and Erk phosphorylation, whereas VPC-23019 inhibited both of these processes, and CYM-50358 had no effects. In contrast, S1P or JTE-013 treatment inhibited adipogenic differentiation of 3T3-F442A preadipocytes, whereas VPC-23019 activated it. The small interfering RNA knockdown of S1pr2 promoted proliferation and inhibited differentiation of 3T3-F442A preadipocytes, whereas that of S1pr1 acted oppositely. Moreover, oral JTE-013 administration improved glucose tolerance/insulin sensitivity in ob/ob mice. Taken together, S1pr2 blockade induced proliferation but suppressed differentiation of (pre)adipocytes both in vivo and in vitro, highlighting a novel therapeutic approach for obesity/type 2 diabetes.
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Herr DR, Reolo MJY, Peh YX, Wang W, Lee CW, Rivera R, Paterson IC, Chun J. Sphingosine 1-phosphate receptor 2 (S1P2) attenuates reactive oxygen species formation and inhibits cell death: implications for otoprotective therapy. Sci Rep 2016; 6:24541. [PMID: 27080739 PMCID: PMC4832229 DOI: 10.1038/srep24541] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 03/31/2016] [Indexed: 01/01/2023] Open
Abstract
Ototoxic drugs, such as platinum-based chemotherapeutics, often lead to permanent hearing loss through apoptosis of neuroepithelial hair cells and afferent neurons of the cochlea. There is no approved therapy for preventing or reversing this process. Our previous studies identified a G protein-coupled receptor (GPCR), S1P2, as a potential mediator of otoprotection. We therefore sought to identify a pharmacological approach to prevent cochlear degeneration via activation of S1P2. The cochleae of S1pr2−/− knockout mice were evaluated for accumulation of reactive oxygen species (ROS) with a nitro blue tetrazolium (NBT) assay. This showed that loss of S1P2 results in accumulation of ROS that precedes progressive cochlear degeneration as previously reported. These findings were supported by in vitro cell-based assays to evaluate cell viability, induction of apoptosis, and accumulation of ROS following activation of S1P2 in the presence of cisplatin. We show for the first time, that activation of S1P2 with a selective receptor agonist increases cell viability and reduces cisplatin-mediated cell death by reducing ROS. Cumulatively, these results suggest that S1P2 may serve as a therapeutic target for attenuating cisplatin-mediated ototoxicity.
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Nishioka T, Arima N, Kano K, Hama K, Itai E, Yukiura H, Kise R, Inoue A, Kim SH, Solnica-Krezel L, Moolenaar WH, Chun J, Aoki J. ATX-LPA1 axis contributes to proliferation of chondrocytes by regulating fibronectin assembly leading to proper cartilage formation. Sci Rep 2016; 6:23433. [PMID: 27005960 PMCID: PMC4804234 DOI: 10.1038/srep23433] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 03/07/2016] [Indexed: 12/20/2022] Open
Abstract
The lipid mediator lysophosphatidic acid (LPA) signals via six distinct G protein-coupled receptors to mediate both unique and overlapping biological effects, including cell migration, proliferation and survival. LPA is produced extracellularly by autotaxin (ATX), a secreted lysophospholipase D, from lysophosphatidylcholine. ATX-LPA receptor signaling is essential for normal development and implicated in various (patho)physiological processes, but underlying mechanisms remain incompletely understood. Through gene targeting approaches in zebrafish and mice, we show here that loss of ATX-LPA1 signaling leads to disorganization of chondrocytes, causing severe defects in cartilage formation. Mechanistically, ATX-LPA1 signaling acts by promoting S-phase entry and cell proliferation of chondrocytes both in vitro and in vivo, at least in part through β1-integrin translocation leading to fibronectin assembly and further extracellular matrix deposition; this in turn promotes chondrocyte-matrix adhesion and cell proliferation. Thus, the ATX-LPA1 axis is a key regulator of cartilage formation.
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Chung H, Vilaysane A, Lau A, Stahl M, Morampudi V, Bondzi-Simpson A, Platnich JM, Bracey NA, French MC, Beck PL, Chun J, Vallance BA, Muruve DA. NLRP3 regulates a non-canonical platform for caspase-8 activation during epithelial cell apoptosis. Cell Death Differ 2016; 23:1331-46. [PMID: 26891693 DOI: 10.1038/cdd.2016.14] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 12/30/2015] [Accepted: 01/20/2016] [Indexed: 12/31/2022] Open
Abstract
Nod-like receptor, pyrin containing 3 (NLRP3) is characterized primarily as a canonical caspase-1 activating inflammasome in macrophages. NLRP3 is also expressed in the epithelium of the kidney and gut; however, its function remains largely undefined. Primary mouse tubular epithelial cells (TEC) lacking Nlrp3 displayed reduced apoptosis downstream of the tumor necrosis factor (TNF) receptor and CD95. TECs were identified as type II apoptotic cells that activated caspase-8, tBid and mitochondrial apoptosis via caspase-9, responses that were reduced in Nlrp3-/- cells. The activation of caspase-8 during extrinsic apoptosis induced by TNFα/cycloheximide (TNFα/CHX) was dependent on adaptor protein apoptosis-associated speck-like protein containing a CARD (ASC) and completely independent of caspase-1 or caspase-11. TECs and primary human proximal tubular epithelial cells (HPTC) did not activate a canonical inflammasome, caspase-1, or IL-1β secretion in response to TNFα/CHX or NLRP3-dependent triggers, such as ATP or nigericin. In cell fractionation studies and by confocal microscopy, NLRP3 colocalized with ASC and caspase-8 in speck-like complexes at the mitochondria during apoptosis. The formation of NLRP3/ASC/caspase-8 specks in response to TNFα/CHX was downstream of TNFR signaling and dependent on potassium efflux. Epithelial ASC specks were present in enteroids undergoing apoptosis and in the injured tubules of wild-type but not Nlrp3-/- or ASC-/- mice following ureteric unilateral obstruction in vivo. These data show that NLRP3 and ASC form a conserved non-canonical platform for caspase-8 activation, independent of the inflammasome that regulates apoptosis within epithelial cells.
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Wood M, Schnabel F, Chun J, Schwartz S, Rounds T, Cuke M. Abstract P6-09-13: Multi-institutional evaluation of women at high-risk for developing breast cancer. Cancer Res 2016. [DOI: 10.1158/1538-7445.sabcs15-p6-09-13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background
Well-established risk factors for breast cancer (BC) include family history, BRCA mutations and biopsies with atypical hyperplasia (AH) or lobular carcinoma in situ (LCIS). Several institutions have registries of these high-risk women but outcomes from these registries require large numbers and long follow-up. We sought to compare characteristics between high-risk populations and evaluate early outcomes.
Methods
Women enrolled in IRB-approved high risk registries at NYU Langone Medical Center (NYU) and University of Vermont (UVM) were evaluated for risk category, uptake of prevention and development of breast cancer. Descriptive statistics were used to summarize the data and Pearson's Chi-Square and Fisher's Exact Tests were performed to compare the variables of interest among the two high risk registries.
Results
Between 2003-14, 1035 women enrolled in these high risk registries. There were significant differences in age and risk characteristics but we found a 99% concordance of variables collected between both high risk registries. Among all risk groups there was a low uptake of prevention opportunities, with 8% taking chemoprevention and 7% undergoing risk-reducing surgeries. Women with AH/LCIS accounted for 66% of those choosing chemoprevention while women with BRCA mutations accounted for 76% of those undergoing risk-reducing surgeries. To date, 43 women (4%) have been diagnosed with breast cancer. 86% were diagnosed with stage 0-1 disease and 70% had moderate or poorly differentiated cancers. There was no significant difference in background risk characteristics when comparing those with breast cancer to those who have not yet developed breast cancer.
Table 1. Clinicopathologic Characteristics between UVM and NYUVARIABLESUVM (N=496, 48%)%NYU (N=539, 52%)%P-valueMEDIAN AGE (years)46 (20-75)50 (20-87)p<0.001RISK FACTORSOne or more 1° relative with BC4428928653p<0.001BRCA positive2559217p<0.001AH631324545p<0.001LCIS22411221p<0.001UPTAKE OF BC PREVENTION METHODSChemoprevention2755410p<0.01Prophylactic bilateral mastectomy10.2458p<0.001Bilateral salpingo-oophorectomy10.2428p<0.001DEVELOPED BC316122p<0.01STAGE OF BC000542p<0.01I2684650 IIA, IIB2618 IIIA, IIIB, IIIC31000
Conclusions
Despite the low uptake of chemoprevention and risk reducing surgery, only 4% of patients went on to develop breast cancer in the study period. The majority of cancers involved moderate or high-grade lesions and were early stage, suggesting a benefit to participation in surveillance programs. We have demonstrated a high degree of concordance between high risk registries, suggesting no barriers to multi-institutional collaboration. High risk registries represent an important resource for studies into methods to prevent breast cancer and improve outcomes from this disease.
Citation Format: Wood M, Schnabel F, Chun J, Schwartz S, Rounds T, Cuke M. Multi-institutional evaluation of women at high-risk for developing breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-09-13.
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Schnabel F, Guth A, Axelrod D, Chun J, Schwartz S, Shapiro R. Abstract P2-12-12: MarginProbe device use and re-excision rates for breast conservation surgeries. Cancer Res 2016. [DOI: 10.1158/1538-7445.sabcs15-p2-12-12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: Current methods of intraoperative assessment of lumpectomy margins are limited. Previous studies have found a lower rate of re-excisions with the adjunctive use of the MarginProbe device (Dune Medical Devices Ltd, Israel). The purpose of this study was to compare the tumor characteristics and re-excision rates before and after the use of MarginProbe for patients who had breast conservation surgery (BCS) at our institution.
Methods: The Breast Cancer Database of our medical center was queried for patients who underwent BCS from 1/2010-3/2015 by three breast surgeons. 2 surgeons used the MarginProbe to direct excision of additional margins at the time of primary lumpectomy surgery and 1 surgeon performed routine 6-surface cavity shavings. We compared our historical data (1/2010-12/2014) to MarginProbe data (1/2015-4/2015). The following variables were included: age, mammographic breast density, tumor characteristics, and re-excision rates. Statistical analyses were performed using Pearson's Chi-Square and Fisher's Exact Tests.
Results: We had a total of 1201 women who had BCS among the 3 breast surgeons. The median age was 61 years. The median invasive size was 1.2 cm. Majority of cancers were early stage (stage 0, I), invasive ductal carcinoma (61%), ER-positive (86%), PR-positive (74%), and Her2Neu-negative (88%). These tumor characteristics were not statistically different in the pre- and post-MarginProbe groups. The majority of patients had dense breasts (51%) and density did not differ among the pre- and post-MarginProbe groups (p=0.86). For the surgeons who used the MarginProbe for margin assessment at the time of surgery, the re-excision rate fell from 17% to 0% and 35% to 20% during the 4-month period. In contrast, the surgeon who routinely performed 6-surface shavings had a re-excision rate that fell from 13% to 12% in the same time period. 88% of MarginProbe readings were false positive. There was one false negative reading.
Table 1. Tumor CharacteristicsVARIABLESTotal N=1201%No MarginProbe (N=1144, 95%)%MarginProbe (N=57, 5%)%P-valueTUMOR STAGE0292242782414240.95I64454614543053 IIA, IIB22319211191221 IIIA, IIIB, IIIC39338312 IV30.330.300 HISTOLOGYDuctal carcinoma in situ305252892516280.75Invasive ductal carcinoma73061695613561 Invasive lobular carcinoma1129107959 Invasive other54553512 ESTROGEN RECEPTOR STATUSNegative16314157146110.46Positive101486963865189 PROGESTERONE RECEPTOR STATUSNegative307262942613230.56Positive86774823744477 HER2-NEU STATUSNegative788887538835810.22Positive92108610614 Equivocal19217225
Conclusions: Routine use of the MarginProbe device was associated with lower re-excision rates compared to historical data and concurrent 6-cavity shaving approach. Better intraoperative margin assessment and lower re-excision rates will decrease the burden of breast cancer on patients and the health care system and support the practice of breast conserving surgery.
Citation Format: Schnabel F, Guth A, Axelrod D, Chun J, Schwartz S, Shapiro R. MarginProbe device use and re-excision rates for breast conservation surgeries. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-12-12.
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Fan J, Salathia N, Liu R, Kaeser GE, Yung YC, Herman JL, Kaper F, Fan JB, Zhang K, Chun J, Kharchenko PV. Characterizing transcriptional heterogeneity through pathway and gene set overdispersion analysis. Nat Methods 2016; 13:241-4. [PMID: 26780092 PMCID: PMC4772672 DOI: 10.1038/nmeth.3734] [Citation(s) in RCA: 309] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 12/16/2015] [Indexed: 12/23/2022]
Abstract
The transcriptional state of a cell reflects a variety of biological factors, from persistent cell-type specific features to transient processes such as cell cycle. Depending on biological context, all such aspects of transcriptional heterogeneity may be of interest, but detecting them from noisy single-cell RNA-seq data remains challenging. We developed PAGODA to resolve multiple, potentially overlapping aspects of transcriptional heterogeneity by testing gene sets for coordinated variability amongst measured cells.
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Manschreck TC, Chun J, Merrill AM, Maher BA, Boshes RA, Glatt SJ, Faraone SV, Tsuang MT, Seidman LJ. Impaired motor performance in adolescents at familial high-risk for schizophrenia. Schizophr Res 2015; 168:44-9. [PMID: 26165939 DOI: 10.1016/j.schres.2015.06.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 06/13/2015] [Accepted: 06/15/2015] [Indexed: 11/30/2022]
Abstract
BACKGROUND The Harvard Adolescent Family High Risk (FHR) Study examined multiple domains of function in young relatives of individuals diagnosed with schizophrenia to identify precursors of the illness. One such area is motor performance, which is deviant in people with schizophrenia and in children at risk for schizophrenia, usually offspring. The present study assessed accuracy of motor performance and degree of lateralization in FHR adolescents and young adults. METHODS Subjects were 33 non-psychotic, first-degree relatives of individuals diagnosed with schizophrenia, and 30 non-psychotic comparison subjects (NpC), ranging in age from 13 to 25 who were compared using a line-drawing task. RESULTS FHR individuals exhibited less precise and coordinated line drawing but greater degree of lateralization than controls. Performance on the linedrawing task was correlated with degree of genetic loading, a possible predictor of higher risk for schizophrenia in the pedigree. CONCLUSIONS The observation of increased motor deviance and increased lateralization in FHR can be utilized in identification and initiation of the treatment in those at high risk in order to prevent or delay the full manifestation of this devastating condition. The use of a rigorously quantified measure is likely to add to the sensitivity of measuring motor performance, especially when impairments may be subtle.
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Kihara Y, Groves A, Rivera RR, Chun J. Dimethyl fumarate inhibits integrin α4 expression in multiple sclerosis models. Ann Clin Transl Neurol 2015; 2:978-83. [PMID: 26478898 PMCID: PMC4603381 DOI: 10.1002/acn3.251] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 08/14/2015] [Accepted: 08/21/2015] [Indexed: 12/25/2022] Open
Abstract
Dimethyl fumarate is an orally bioavailable compound for the treatment of multiple sclerosis and psoriasis. A mechanism involving nuclear factor erythroid 2-like 2 activation has been proposed to account for its efficacy in multiple sclerosis. Here, we report that dimethyl fumarate inhibits expression of integrin α4 on circulating lymphocytes in experimental autoimmune encephalomyelitis mice and also on activated human Jurkat T cells in a manner distinct from nuclear factor erythroid 2-like 2 activation. Our results offer an alternative mechanism for the efficacy of dimethyl fumarate in multiple sclerosis.
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120
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Yung BS, Xiang SY, Purcell N, Rosen H, Chun J, Heller Brown J, Miyamoto S. Abstract 424: Activation of the S1P3 Receptors is Responsible for S1P-mediated RhoA Activation and Cardioprotection. Circ Res 2015. [DOI: 10.1161/res.117.suppl_1.424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sphingosine-1-phoshpate (S1P) is a bioactive lysophospholipid, generated and released at sites of tissue injury. S1P signals through a variety of G-protein coupled receptor subtypes and there are three major sub-types, S1P
1
, S1P
2
, and S1P
3
, to mediate cardiovascular responses. S1P
2
and S1P
3
receptors couple to Gα
i
, Gα
12
, Gα
13
and Gα
q
and we first examined the contribution of S1P
2
and S1P
3
to cardiac hypertrophy using S1P
2
and S1P
3
knockout (KO) mice and found that there is no difference in hypertrophy induced by pressure-overload. We previously showed that S1P provides cardioprotection against oxidative stress such as ischemia/reperfusion in which RhoA activation and its downstream effector PKD1 play an important role. It has not, however, been determined which S1P receptor subtype is responsible for S1P mediated cardioprotection. We knocked down the three major S1P receptors using siRNA in neonatal rat ventricular myocytes (NRVMs) and assessed RhoA and PKD1 activation induced by S1P. Knockdown of S1P
3
abolished RhoA activation and largely attenuated phosphorylation of PKD1 while knockdown of S1P
1
and S1P
2
did not. Using siRNA or pertussis toxin to inhibit different G-proteins, we further established that S1P
regulates RhoA activation through Gα
13
, but not Gα
12
, Gα
q
,
or Gα
i
. To investigate the role of S1P
3
receptors in the adult heart, hearts were isolated from wild-type or S1P
3
KO adult mice, perfused in the Langendorff mode and subjected to ex vivo ischemia/reperfusion. As previously reported, S1P perfusion significantly reduced infarct size induced by ischemia/reperfusion in WT hearts (by 50%), but this protection was abolished in the S1P
3
KO mouse heart. To further confirm the role of S1P
3
in cardioprotection we perfused WT mouse hearts with an S1P
3
-specific agonist CYM-51736. We observed that CYM-51736 attenuated the infarct size to a similar degree as that observed with S1P. Our findings reveal that activation of the S1P
3
receptor coupling to Gα
13
and subsequent RhoA activation is responsible for cardioprotection against ischemia/reperfusion. Accordingly specific drug targeting of S1P
3
receptors could provide therapeutic benefits in ischemic heart disease without the undesirable effects of global activation of other cardiac S1P receptors.
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Abstract
Lysophosphatidic acid (LPA) is a bioactive phospholipid that is present in all tissues examined to date. LPA signals extracellularly via cognate G protein-coupled receptors to mediate cellular processes such as survival, proliferation, differentiation, migration, adhesion and morphology. These LPA-influenced processes impact many aspects of organismal development. In particular, LPA signalling has been shown to affect fertility and reproduction, formation of the nervous system, and development of the vasculature. Here and in the accompanying poster, we review the developmentally related features of LPA signalling.
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Xu K, Ma L, Li Y, Wang F, Zheng GY, Sun Z, Jiang F, Chen Y, Liu H, Dang A, Chen X, Chun J, Tian XL. Genetic and Functional Evidence Supports LPAR1 as a Susceptibility Gene for Hypertension. Hypertension 2015; 66:641-6. [PMID: 26123684 DOI: 10.1161/hypertensionaha.115.05515] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/08/2015] [Indexed: 01/11/2023]
Abstract
Essential hypertension is a complex disease affected by genetic and environmental factors and serves as a major risk factor for cardiovascular diseases. Serum lysophosphatidic acid correlates with an elevated blood pressure in rats, and lysophosphatidic acid interacts with 6 subtypes of receptors. In this study, we assessed the genetic association of lysophosphatidic acid receptors with essential hypertension by genotyping 28 single-nucleotide polymorphisms from genes encoding for lysophosphatidic acid receptors, LPAR1, LPAR2, LPAR3, LPAR4, LPAR5, and LPAR6 and their flanking sequences, in 3 Han Chinese cohorts consisting of 2630 patients and 3171 controls in total. We identified a single-nucleotide polymorphism, rs531003 in the 3'-flanking genomic region of LPAR1, associated with hypertension (the Bonferroni corrected P=1.09×10(-5), odds ratio [95% confidence interval]=1.23 [1.13-1.33]). The risk allele C of rs531003 is associated with the increased expression of LPAR1 and the susceptibility of hypertension, particularly in those with a shortage of sleep (P=4.73×10(-5), odds ratio [95% confidence interval]=1.75 [1.34-2.28]). We further demonstrated that blood pressure elevation caused by sleep deprivation and phenylephrine-induced vasoconstriction was both diminished in LPAR1-deficient mice. Together, we show that LPAR1 is a novel susceptibility gene for human essential hypertension and that stress, such as shortage of sleep, increases the susceptibility of patients with risk allele to essential hypertension.
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Chrencik JE, Roth CB, Terakado M, Kurata H, Omi R, Kihara Y, Warshaviak D, Nakade S, Asmar-Rovira G, Mileni M, Mizuno H, Griffith MT, Rodgers C, Han GW, Velasquez J, Chun J, Stevens RC, Hanson MA. Crystal Structure of Antagonist Bound Human Lysophosphatidic Acid Receptor 1. Cell 2015; 161:1633-43. [PMID: 26091040 PMCID: PMC4476059 DOI: 10.1016/j.cell.2015.06.002] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/17/2015] [Accepted: 05/27/2015] [Indexed: 12/23/2022]
Abstract
Lipid biology continues to emerge as an area of significant therapeutic interest, particularly as the result of an enhanced understanding of the wealth of signaling molecules with diverse physiological properties. This growth in knowledge is epitomized by lysophosphatidic acid (LPA), which functions through interactions with at least six cognate G protein-coupled receptors. Herein, we present three crystal structures of LPA1 in complex with antagonist tool compounds selected and designed through structural and stability analyses. Structural analysis combined with molecular dynamics identified a basis for ligand access to the LPA1 binding pocket from the extracellular space contrasting with the proposed access for the sphingosine 1-phosphate receptor. Characteristics of the LPA1 binding pocket raise the possibility of promiscuous ligand recognition of phosphorylated endocannabinoids. Cell-based assays confirmed this hypothesis, linking the distinct receptor systems through metabolically related ligands with potential functional and therapeutic implications for treatment of disease.
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González de San Román E, Manuel I, Giralt MT, Chun J, Estivill-Torrús G, Rodríguez de Fonseca F, Santín LJ, Ferrer I, Rodríguez-Puertas R. Anatomical location of LPA1 activation and LPA phospholipid precursors in rodent and human brain. J Neurochem 2015; 134:471-85. [PMID: 25857358 DOI: 10.1111/jnc.13112] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/02/2015] [Accepted: 03/31/2015] [Indexed: 12/29/2022]
Abstract
Lysophosphatidic acid (LPA) is a signaling molecule that binds to six known G protein-coupled receptors: LPA1 -LPA6 . LPA evokes several responses in the CNS, including cortical development and folding, growth of the axonal cone and its retraction process. Those cell processes involve survival, migration, adhesion proliferation, differentiation, and myelination. The anatomical localization of LPA1 is incompletely understood, particularly with regard to LPA binding. Therefore, we have used functional [(35) S]GTPγS autoradiography to verify the anatomical distribution of LPA1 binding sites in adult rodent and human brain. The greatest activity was observed in myelinated areas of the white matter such as corpus callosum, internal capsule and cerebellum. MaLPA1 -null mice (a variant of LPA1 -null) lack [(35) S]GTPγS basal binding in white matter areas, where the LPA1 receptor is expressed at high levels, suggesting a relevant role of the activity of this receptor in the most myelinated brain areas. In addition, phospholipid precursors of LPA were localized by MALDI-IMS in both rodent and human brain slices identifying numerous species of phosphatides and phosphatidylcholines. Both phosphatides and phosphatidylcholines species represent potential LPA precursors. The anatomical distribution of these precursors in rodent and human brain may indicate a metabolic relationship between LPA and LPA1 receptors. Lysophosphatidic acid (LPA) is a signaling molecule that binds to six known G protein-coupled receptors (GPCR), LPA1 to LPA6 . LPA evokes several responses in the central nervous system (CNS), including cortical development and folding, growth of the axonal cone and its retraction process. We used functional [(35) S]GTPγS autoradiography to verify the anatomical distribution of LPA1 -binding sites in adult rodent and human brain. The distribution of LPA1 receptors in rat, mouse and human brains show the highest activity in white matter myelinated areas. The basal and LPA-evoked activities are abolished in MaLPA1 -null mice. The phospholipid precursors of LPA are localized by MALDI-IMS. The anatomical distribution of LPA precursors in rodent and human brain suggests a relationship with functional LPA1 receptors.
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Park OJ, Yi H, Jeon J, Kang SS, Koo KT, Kum KY, Chun J, Yun CH, Han S. Pyrosequencing Analysis of Subgingival Microbiota in Distinct Periodontal Conditions. J Dent Res 2015; 94:921-7. [DOI: 10.1177/0022034515583531] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Subgingival microorganisms are potentially associated with periodontal diseases. However, changes in the subgingival microbiota during the progress of periodontal diseases are poorly understood. In this study, we analyzed bacterial communities in the subgingival paper point samples from 32 Korean individuals with no sign of disease, gingivitis, or periodontitis using 454 FLX Titanium pyrosequencing. A total of 256,113 reads representing 26 phyla, 433 genera, and 1,016 species were detected. Bacteroidetes, Fusobacteria, Synergistetes, and Spirochaetes were the abundant phyla in periodontitis subjects, whereas Firmicutes and Proteobacteria were identified as the dominant phyla in the gingivitis and healthy subjects, respectively. Although high levels of Porphyromonas, Fusobacterium, Fretibacterium, Rothia, Filifactor, and Treponema genera were observed in the periodontitis subjects, Streptococcus, Capnocytophaga, Leptotrichia, and Haemophilus genera were found at high frequency in the gingivitis subjects. Species including Porphyromonas gingivalis, Fusobacterium nucleatum, and Fretibacterium fastidiosum were significantly increased in periodontitis subjects. On the other hand, Streptococcus pseudopneumoniae, Haemophilus parainfluenzae, and Leptotrichia hongkongensis were preferentially observed in the gingivitis subjects. Intriguingly, the halophile Halomonas hamiltonii was revealed as a predominant species in the healthy subjects. Based on Fast UniFrac analysis, distinctive bacterial clusters were classified for the healthy, gingivitis, and periodontitis state. The current findings might be useful for understanding the pathogenesis, diagnosis, and treatment of periodontal diseases.
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