Epigenetic modifications in the GH-dependent Prlr, Hnf6, Cyp7b1, Adh1 and Cyp2a4 genes

in Journal of Molecular Endocrinology
View More View Less
  • 1 Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina

Correspondence should be addressed to D Becu-Villalobos: dbecu@dna.uba.ar
Restricted access

Many sex differences in liver gene expression originate in the brain, depend on GH secretion and may underlie sex disparities in hepatic disease. Because epigenetic mechanisms may contribute, we studied promoter methylation and microRNA abundance in the liver, associated with expression of sexual dimorphic genes in mice with selective disruption of the dopamine D2 receptor in neurons (neuroDrd2KO), which decreases hypothalamic Ghrh, pituitary GH, and serum IGFI and in neonatally androgenized female mice which have increased pituitary GH content and serum IGFI. We evaluated mRNA levels of the female predominant genes prolactin receptor (Prlr), alcohol dehydrogenase 1 (Adh1), Cyp2a4, and hepatocyte nuclear transcription factor 6 (Hnf6) and the male predominant gene, Cyp7b1. Female predominant genes had higher mRNA levels compared to males, but lower methylation was only detected in the Prlr and Cyp2a4 female promoters. In neuroDrd2KO mice, sexual dimorphism was lost for all genes; the upregulation (feminization) of Prlr and Cyp2a4 in males correlated with decreased methylation of their promoters, and the downregulation (masculinization) of Hnf-6 mRNA in females correlated inversely with its promoter methylation. Neonatal androgenization of females evoked a loss of sexual dimorphism only for the female predominant Hnf6 and Adh1 genes, but no differences in promoter methylation were found. Finally, mmu-miR-155-5p, predicted to target Cyp7b1 expression, was lower in males in association with higher Cyp7b1 mRNA levels compared to females and was not modified in neuroDrd2KO or TP mice. Our results suggest specific regulation of gene sexually dimorphic expression in the liver by methylation or miRNAs.

 

      Society for Endocrinology

Sept 2018 onwards Past Year Past 30 Days
Abstract Views 1138 1138 82
Full Text Views 24 24 0
PDF Downloads 19 19 0
  • Bello EP, Mateo Y, Gelman DM, Noain D, Shin JH, Low MJ, Alvarez VA, Lovinger DM & Rubinstein M 2011 Cocaine supersensitivity and enhanced motivation for reward in mice lacking dopamine D2 autoreceptors. Nature Neuroscience 14 10331038. (https://doi.org/10.1038/nn.2862)

    • Search Google Scholar
    • Export Citation
  • Bolotin E, Chellappa K, Hwang-Verslues W, Schnabl JM, Yang C & Sladek FM 2011 Nuclear receptor HNF4alpha binding sequences are widespread in Alu repeats. BMC Genomics 12 560. (https://doi.org/10.1186/1471-2164-12-560)

    • Search Google Scholar
    • Export Citation
  • Brie B, Ramirez MC, De Winne C, Lopez Vicchi F, Villarruel L, Sorianello E, Catalano P, Ornstein AM & Becu-Villalobos D 2019 Brain control of sexually dimorphic liver function and disease: the endocrine connection. Cellular and Molecular Neurobiology 39 169180. (https://doi.org/10.1007/s10571-019-00652-0)

    • Search Google Scholar
    • Export Citation
  • Buzzetti E, Parikh PM, Gerussi A & Tsochatzis E 2017 Gender differences in liver disease and the drug-dose gender gap. Pharmacological Research 120 97108. (https://doi.org/10.1016/j.phrs.2017.03.014)

    • Search Google Scholar
    • Export Citation
  • Cheung OK & Cheng AS 2016 Gender differences in adipocyte metabolism and liver cancer progression. Frontiers in Genetics 7 168. (https://doi.org/10.3389/fgene.2016.00168)

    • Search Google Scholar
    • Export Citation
  • Clodfelter KH, Miles GD, Wauthier V, Holloway MG, Zhang X, Hodor P, Ray WJ & Waxman DJ 2007 Role of STAT5a in regulation of sex-specific gene expression in female but not male mouse liver revealed by microarray analysis. Physiological Genomics 31 6374. (https://doi.org/10.1152/physiolgenomics.00055.2007)

    • Search Google Scholar
    • Export Citation
  • Connerney J, Lau-Corona D, Rampersaud A & Waxman DJ 2017 Activation of male liver chromatin accessibility and STAT5-dependent gene transcription by plasma growth hormone pulses. Endocrinology 158 13861405. (https://doi.org/10.1210/en.2017-00060)

    • Search Google Scholar
    • Export Citation
  • Drakaki A, Hatziapostolou M & Iliopoulos D 2013 Therapeutically targeting microRNAs in liver cancer. Current Pharmaceutical Design 19 11801191. (https://doi.org/10.2174/138161213804805658)

    • Search Google Scholar
    • Export Citation
  • Dreval K, Tryndyak V, de Conti A, Beland FA & Pogribny IP 2019 Gene expression and DNA methylation alterations during non-alcoholic steatohepatitis-associated liver carcinogenesis. Frontiers in Genetics 10 486. (https://doi.org/10.3389/fgene.2019.00486)

    • Search Google Scholar
    • Export Citation
  • Durazzo M, Belci P, Collo A, Prandi V, Pistone E, Martorana M, Gambino R & Bo S 2014 Gender specific medicine in liver diseases: a point of view. World Journal of Gastroenterology 20 21272135. (https://doi.org/10.3748/wjg.v20.i9.2127)

    • Search Google Scholar
    • Export Citation
  • Ellefson WM, Lakner AM, Hamilton A, McKillop IH, Bonkovsky HL, Steuerwald NM, Huet YM & Schrum LW 2011 Neonatal androgenization exacerbates alcohol-induced liver injury in adult rats, an effect abrogated by estrogen. PLoS ONE 6 e29463. (https://doi.org/10.1371/journal.pone.0029463)

    • Search Google Scholar
    • Export Citation
  • Forsander OA & Sinclair JD 1992 Alcohol elimination and the regulation of alcohol consumption in AA and ANA rats. Alcohol and Alcoholism 27 411416. (https://doi.org/10.1093/oxfordjournals.alcalc.a045266)

    • Search Google Scholar
    • Export Citation
  • García-Calzón S, Perfilyev A, de Mello VD, Pihlajamäki J & Ling C 2018 Sex differences in the methylome and transcriptome of the human liver and circulating HDL-cholesterol levels. Journal of Clinical Endocrinology and Metabolism 103 43954408. (https://doi.org/10.1210/jc.2018-00423)

    • Search Google Scholar
    • Export Citation
  • Garcia-Carpizo V, Ruiz-Llorente L, Fraga M & Aranda A 2011 The growing role of gene methylation on endocrine function. Journal of Molecular Endocrinology 47 R75R89. (https://doi.org/10.1530/JME-11-0059)

    • Search Google Scholar
    • Export Citation
  • Garzon R, Marcucci G & Croce CM 2010 Targeting microRNAs in cancer: rationale, strategies and challenges. Nature Reviews: Drug Discovery 9 775789. (https://doi.org/10.1038/nrd3179)

    • Search Google Scholar
    • Export Citation
  • Goffin V, Binart N, Touraine P & Kelly PA 2002 Prolactin: the new biology of an old hormone. Annual Review of Physiology 64 4767. (https://doi.org/10.1146/annurev.physiol.64.081501.131049)

    • Search Google Scholar
    • Export Citation
  • Goldhar AS, Duan R, Ginsburg E & Vonderhaar BK 2011 Progesterone induces expression of the prolactin receptor gene through cooperative action of Sp1 and C/EBP. Molecular and Cellular Endocrinology 335 148157. (https://doi.org/10.1016/j.mce.2011.01.004)

    • Search Google Scholar
    • Export Citation
  • Guy J & Peters MG 2013 Liver disease in women: the influence of gender on epidemiology, natural history, and patient outcomes. Gastroenterology and Hepatology 9 633639.

    • Search Google Scholar
    • Export Citation
  • Hao P & Waxman DJ 2018 Functional roles of sex-biased, growth hormone-regulated microRNAs miR-1948 and miR-802 in young adult mouse liver. Endocrinology 159 13771392. (https://doi.org/10.1210/en.2017-03109)

    • Search Google Scholar
    • Export Citation
  • Hartwell HJ, Petrosky KY, Fox JG, Horseman ND & Rogers AB 2014 Prolactin prevents hepatocellular carcinoma by restricting innate immune activation of c-Myc in mice. PNAS 111 1145511460. (https://doi.org/10.1073/pnas.1404267111)

    • Search Google Scholar
    • Export Citation
  • Holloway MG, Laz EV & Waxman DJ 2006 Codependence of Growth Hormone-Responsive, Sexually Dimorphic Hepatic Gene Expression on Signal Transducer and Activator of Transcription 5b and Hepatic Nuclear Factor 4α. Molecular Endocrinology 20 647660. (https://doi.org/10.1210/me.2005-0328)

    • Search Google Scholar
    • Export Citation
  • Issa JP 2007 DNA methylation as a therapeutic target in cancer. Clinical Cancer Research 13 16341637. (https://doi.org/10.1158/1078-0432.CCR-06-2076)

    • Search Google Scholar
    • Export Citation
  • Jansson JO & Frohman LA 1987 Differential effects of neonatal and adult androgen exposure on the growth hormone secretory pattern in male rats. Endocrinology 120 15511557. (https://doi.org/10.1210/endo-120-4-1551)

    • Search Google Scholar
    • Export Citation
  • Lahuna O, Rastegar M, Maiter D, Thissen JP, Lemaigre FP & Rousseau GG 2000 Involvement of STAT5 (signal transducer and activator of transcription 5) and HNF-4 (hepatocyte nuclear factor 4) in the transcriptional control of the hnf6 gene by growth hormone. Molecular Endocrinology 14 285294. (https://doi.org/10.1210/mend.14.2.0423)

    • Search Google Scholar
    • Export Citation
  • Lau-Corona D, Suvorov A & Waxman DJ 2017 Feminization of male mouse liver by persistent growth hormone stimulation: activation of sex-biased transcriptional networks and dynamic changes in chromatin states. Molecular and Cellular Biology 37 0030100317. (https://doi.org/10.1128/MCB.00301-17)

    • Search Google Scholar
    • Export Citation
  • Lavery DJ, Lopez-Molina L, Margueron R, Fleury-Olela F, Conquet F, Schibler U & Bonfils C 1999 Circadian expression of the steroid 15 alpha-hydroxylase (Cyp2a4) and coumarin 7-hydroxylase (Cyp2a5) genes in mouse liver is regulated by the PAR leucine zipper transcription factor DBP. Molecular and Cellular Biology 19 64886499. (https://doi.org/10.1128/mcb.19.10.6488)

    • Search Google Scholar
    • Export Citation
  • Lenz KM, Nugent BM & McCarthy MM 2012 Sexual differentiation of the rodent brain: dogma and beyond. Frontiers in Neuroscience 6 26. (https://doi.org/10.3389/fnins.2012.00026)

    • Search Google Scholar
    • Export Citation
  • Liao D, Porsch-Hallstrom I, Gustafsson JA & Blanck A 1993 Sex differences at the initiation stage of rat liver carcinogenesis–influence of growth hormone. Carcinogenesis 14 20452049. (https://doi.org/10.1093/carcin/14.10.2045)

    • Search Google Scholar
    • Export Citation
  • Ling G, Sugathan A, Mazor T, Fraenkel E & Waxman DJ 2010 Unbiased, genome-wide in vivo mapping of transcriptional regulatory elements reveals sex differences in chromatin structure associated with sex-specific liver gene expression. Molecular and Cellular Biology 30 55315544. (https://doi.org/10.1128/MCB.00601-10)

    • Search Google Scholar
    • Export Citation
  • Liu W, Xie Y, Ma J, Luo X, Nie P, Zuo Z, Lahrmann U, Zhao Q, Zheng Y, Zhao Y, et al. 2015 IBS: an illustrator for the presentation and visualization of biological sequences. Bioinformatics 31 33593361. (https://doi.org/10.1093/bioinformatics/btv362)

    • Search Google Scholar
    • Export Citation
  • Livne I, Silverman AJ & Gibson MJ 1992 Reversal of reproductive deficiency in the hpg male mouse by neonatal androgenization. Biology of Reproduction 47 561567. (https://doi.org/10.1095/biolreprod47.4.561)

    • Search Google Scholar
    • Export Citation
  • Lopez-Vicchi F & Becu-Villalobos D 2017 Prolactin: the bright and the dark side. Endocrinology 158 15561559. (https://doi.org/10.1210/en.2017-00184)

    • Search Google Scholar
    • Export Citation
  • Lu TP, Lee CY, Tsai MH, Chiu YC, Hsiao CK, Lai LC & Chuang EY 2012 miRSystem: an integrated system for characterizing enriched functions and pathways of microRNA targets. PLoS ONE 7 e42390. (https://doi.org/10.1371/journal.pone.0042390)

    • Search Google Scholar
    • Export Citation
  • Lv D, Liu J, Zhao C, Sun Q, Zhou Q, Xu J & Xiao J 2015 Targeting microRNAs in pathological hypertrophy and cardiac failure. Mini Reviews in Medicinal Chemistry 15 475478. (https://doi.org/10.2174/1389557515666150324124751)

    • Search Google Scholar
    • Export Citation
  • Marin V, Rosso N, Dal Ben M, Raseni A, Boschelle M, Degrassi C, Nemeckova I, Nachtigal P, Avellini C, Tiribelli C, 2016 An animal model for the juvenile non-alcoholic fatty liver disease and non-alcoholic steatohepatitis. PLoS ONE 11 e0158817. (https://doi.org/10.1371/journal.pone.0158817)

    • Search Google Scholar
    • Export Citation
  • Messeguer X, Escudero R, Farre D, Nunez O, Martinez J & Alba MM 2002 PROMO: detection of known transcription regulatory elements using species-tailored searches. Bioinformatics 18 333334. (https://doi.org/10.1093/bioinformatics/18.2.333)

    • Search Google Scholar
    • Export Citation
  • Miura N & Tanaka K 1993 Analysis of the rat hepatocyte nuclear factor (HNF) 1 gene promoter: synergistic activation by HNF4 and HNF1 proteins. Nucleic Acids Research 21 37313736. (https://doi.org/10.1093/nar/21.16.3731)

    • Search Google Scholar
    • Export Citation
  • Moreno-Carranza B, Goya-Arce M, Vega C, Adan N, Triebel J, Lopez-Barrera F, Quintanar-Stephano A, Binart N, Martínez de la Escalera G & Clapp C 2013 Prolactin promotes normal liver growth, survival, and regeneration in rodents: effects on hepatic IL-6, suppressor of cytokine signaling-3, and angiogenesis. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology 305 R720R726. (https://doi.org/10.1152/ajpregu.00282.2013)

    • Search Google Scholar
    • Export Citation
  • Mueller CR, Maire P & Schibler U 1990 DBP, a liver-enriched transcriptional activator, is expressed late in ontogeny and its tissue specificity is determined posttranscriptionally. Cell 61 279291. (https://doi.org/10.1016/0092-8674(90)90808-r)

    • Search Google Scholar
    • Export Citation
  • Negri-Cesi P, Colciago A, Pravettoni A, Casati L, Conti L & Celotti F 2008 Sexual differentiation of the rodent hypothalamus: hormonal and environmental influences. Journal of Steroid Biochemistry and Molecular Biology 109 294299. (https://doi.org/10.1016/j.jsbmb.2008.03.003)

    • Search Google Scholar
    • Export Citation
  • Noain D, Perez-Millan MI, Bello EP, Luque GM, Casas Cordero R, Gelman DM, Peper M, Tornadu IG, Low MJ, Becu-Villalobos D, et al. 2013 Central dopamine D2 receptors regulate growth-hormone-dependent body growth and pheromone signaling to conspecific males. Journal of Neuroscience 33 58345842. (https://doi.org/10.1523/JNEUROSCI.5673-12.2013)

    • Search Google Scholar
    • Export Citation
  • Nugent BM & McCarthy MM 2011 Epigenetic underpinnings of developmental sex differences in the brain. Neuroendocrinology 93 150158. (https://doi.org/10.1159/000325264)

    • Search Google Scholar
    • Export Citation
  • Potter JJ & Mezey E 2001 Effect of STAT5b on rat liver alcohol dehydrogenase. Archives of Biochemistry and Biophysics 391 4148. (https://doi.org/10.1006/abbi.2001.2393)

    • Search Google Scholar
    • Export Citation
  • Poynard T, Bedossa P & Opolon P 1997 Natural history of liver fibrosis progression in patients with chronic hepatitis C. The OBSVIRC, METAVIR, CLINIVIR, and DOSVIRC groups. Lancet 349 825832. (https://doi.org/10.1016/s0140-6736(96)07642-8)

    • Search Google Scholar
    • Export Citation
  • Quintanilla ME, Tampier L, Sapag A, Gerdtzen Z & Israel Y 2007 Sex differences, alcohol dehydrogenase, acetaldehyde burst, and aversion to ethanol in the rat: a systems perspective. American Journal of Physiology: Endocrinology and Metabolism 293 E531E537. (https://doi.org/10.1152/ajpendo.00187.2007)

    • Search Google Scholar
    • Export Citation
  • Ramirez MC, Luque GM, Ornstein AM & Becu-Villalobos D 2010 Differential neonatal testosterone imprinting of GH-dependent liver proteins and genes in female mice. Journal of Endocrinology 207 301308. (https://doi.org/10.1677/JOE-10-0276)

    • Search Google Scholar
    • Export Citation
  • Ramirez MC, Bourguignon NS, Bonaventura MM, Lux-Lantos V, Libertun C & Becu-Villalobos D 2012 Neonatal xenoestrogen exposure alters growth hormone-dependent liver proteins and genes in adult female rats. Toxicology Letters 213 325331. (https://doi.org/10.1016/j.toxlet.2012.07.015)

    • Search Google Scholar
    • Export Citation
  • Ramirez MC, Ornstein AM, Luque GM, Perez-Millan MI, Garcia-Tornadu I, Rubinstein M & Becu-Villalobos D 2015 Pituitary and brain dopamine D2 receptors regulate liver gene sexual dimorphism. Endocrinology 156 10401051. (https://doi.org/10.1210/en.2014-1714)

    • Search Google Scholar
    • Export Citation
  • Reizel Y, Spiro A, Sabag O, Skversky Y, Hecht M, Keshet I, Berman BP & Cedar H 2015 Gender-specific postnatal demethylation and establishment of epigenetic memory. Genes and Development 29 923933. (https://doi.org/10.1101/gad.259309.115)

    • Search Google Scholar
    • Export Citation
  • Rogers AB, Theve EJ, Feng Y, Fry RC, Taghizadeh K, Clapp KM, Boussahmain C, Cormier KS & Fox JG 2007 Hepatocellular carcinoma associated with liver-gender disruption in male mice. Cancer Research 67 1153611546. (https://doi.org/10.1158/0008-5472.CAN-07-1479)

    • Search Google Scholar
    • Export Citation
  • Ruberti F, Barbato C & Cogoni C 2012 Targeting microRNAs in neurons: tools and perspectives. Experimental Neurology 235 419426. (https://doi.org/10.1016/j.expneurol.2011.10.031)

    • Search Google Scholar
    • Export Citation
  • Shao S, Yao Z, Lu J, Song Y, He Z, Yu C, Zhou X, Zhao L, Zhao J & Gao L 2018 Ablation of prolactin receptor increases hepatic triglyceride accumulation. Biochemical and Biophysical Research Communications 498 693699. (https://doi.org/10.1016/j.bbrc.2018.03.048)

    • Search Google Scholar
    • Export Citation
  • Simon FR, Fortune J, Iwahashi M & Sutherland E 2002 Sexual dimorphic expression of ADH in rat liver: importance of the hypothalamic-pituitary-liver axis. American Journal of Physiology: Gastrointestinal and Liver Physiology 283 G646G655. (https://doi.org/10.1152/ajpgi.00438.2001)

    • Search Google Scholar
    • Export Citation
  • Stiles AR, McDonald JG, Bauman DR & Russell DW 2009 CYP7B1: one cytochrome P450, two human genetic diseases, and multiple physiological functions. Journal of Biological Chemistry 284 2848528489. (https://doi.org/10.1074/jbc.R109.042168)

    • Search Google Scholar
    • Export Citation
  • Sueyoshi T, Yokomori N, Korach KS & Negishi M 1999 Developmental action of estrogen receptor-alpha feminizes the growth hormone-Stat5b pathway and expression of Cyp2a4 and Cyp2d9 genes in mouse liver. Molecular Pharmacology 56 473477. (https://doi.org/10.1124/mol.56.3.473)

    • Search Google Scholar
    • Export Citation
  • Sugathan A & Waxman DJ 2013 Genome-wide analysis of chromatin states reveals distinct mechanisms of sex-dependent gene regulation in male and female mouse liver. Molecular and Cellular Biology 33 35943610. (https://doi.org/10.1128/MCB.00280-13)

    • Search Google Scholar
    • Export Citation
  • Tracy TS, Venkataramanan R, Glover DD, Caritis SN & National Institute for Child Health and Human Development Network of Maternal-Fetal-Medicine Units 2005 Temporal changes in drug metabolism (CYP1A2, CYP2D6 and CYP3A Activity) during pregnancy. American Journal of Obstetrics and Gynecology 192 633639. (https://doi.org/10.1016/j.ajog.2004.08.030)

    • Search Google Scholar
    • Export Citation
  • Wang K & Holterman AX 2012 Pathophysiologic role of hepatocyte nuclear factor 6. Cellular Signalling 24 916. (https://doi.org/10.1016/j.cellsig.2011.08.009)

    • Search Google Scholar
    • Export Citation
  • Wauthier V, Sugathan A, Meyer RD, Dombkowski AA & Waxman DJ 2010 Intrinsic sex differences in the early growth hormone responsiveness of sex-specific genes in mouse liver. Molecular Endocrinology 24 667678. (https://doi.org/10.1210/me.2009-0454)

    • Search Google Scholar
    • Export Citation
  • Waxman DJ & Holloway MG 2009 Sex differences in the expression of hepatic drug metabolizing enzymes. Molecular Pharmacology 76 215228. (https://doi.org/10.1124/mol.109.056705)

    • Search Google Scholar
    • Export Citation
  • Wiwi CA, Gupte M & Waxman DJ 2004 Sexually dimorphic P450 gene expression in liver-specific hepatocyte nuclear factor 4alpha-deficient mice. Molecular Endocrinology 18 19751987. (https://doi.org/10.1210/me.2004-0129)

    • Search Google Scholar
    • Export Citation
  • Wong JH, Dukes J, Levy RE, Sos B, Mason SE, Fong TS & Weiss EJ 2008 Sex differences in thrombosis in mice are mediated by sex-specific growth hormone secretion patterns. Journal of Clinical Investigation 118 29692978. (https://doi.org/10.1172/JCI34957)

    • Search Google Scholar
    • Export Citation
  • Yokomori N, Kobayashi R, Moore R, Sueyoshi T & Negishi M 1995 A DNA methylation site in the male-specific P450 (Cyp 2d-9) promoter and binding of the heteromeric transcription factor GABP. Molecular and Cellular Biology 15 53555362. (https://doi.org/10.1128/mcb.15.10.5355)

    • Search Google Scholar
    • Export Citation
  • Yoshida Y, Hughes DE, Rausa FM III, Kim IM, Tan Y, Darlington GJ & Costa RH 2006 C/EBPalpha and HNF6 protein complex formation stimulates HNF6-dependent transcription by CBP coactivator recruitment in HepG2 cells. Hepatology 43 276286. (https://doi.org/10.1002/hep.21044)

    • Search Google Scholar
    • Export Citation
  • Zhang Y, Klein K, Sugathan A, Nassery N, Dombkowski A, Zanger UM & Waxman DJ 2011 Transcriptional profiling of human liver identifies sex-biased genes associated with polygenic dyslipidemia and coronary artery disease. PLoS ONE 6 e23506. (https://doi.org/10.1371/journal.pone.0023506)

    • Search Google Scholar
    • Export Citation
  • Zhang Y, Laz EV & Waxman DJ 2012 Dynamic, sex-differential STAT5 and BCL6 binding to sex-biased, growth hormone-regulated genes in adult mouse liver. Molecular and Cellular Biology 32 880896. (https://doi.org/10.1128/MCB.06312-11)

    • Search Google Scholar
    • Export Citation
  • Zhang P, Ge Z, Wang H, Feng W, Sun X, Chu X, Jiang C, Wang Y, Zhu D & Bi Y 2018 Prolactin improves hepatic steatosis via CD36 pathway. Journal of Hepatology 68 12471255. (https://doi.org/10.1016/j.jhep.2018.01.035)

    • Search Google Scholar
    • Export Citation