title: Glucocorticoid receptor is required for foetal heart maturation.
abstract: Glucocorticoids are vital for the structural and functional maturation of foetal organs, yet excessive foetal exposure is detrimental to adult cardiovascular health. To elucidate the role of glucocorticoid signalling in late-gestation cardiovascular maturation, we have generated mice with conditional disruption of glucocorticoid receptor (GR) in cardiomyocytes and vascular smooth muscle cells using smooth muscle protein 22-driven Cre recombinase (SMGRKO mice) and compared them with mice with global deficiency in GR (GR(-/-)). Echocardiography shows impaired heart function in both SMGRKO and GR(-/-) mice at embryonic day (E)17.5, associated with generalized oedema. Cardiac ultrastructure is markedly disrupted in both SMGRKO and GR(-/-) mice at E17.5, with short, disorganized myofibrils and cardiomyocytes that fail to align in the compact myocardium. Failure to induce critical genes involved in contractile function, calcium handling and energy metabolism underpins this common phenotype. However, although hearts of GR(-/-) mice are smaller, with 22% reduced ventricular volume at E17.5, SMGRKO hearts are normally sized. Moreover, while levels of mRNA encoding atrial natriuretic peptide are reduced in E17.5 GR(-/-) hearts, they are normal in foetal SMGRKO hearts. These data demonstrate that structural, functional and biochemical maturation of the foetal heart is dependent on glucocorticoid signalling within cardiomyocytes and vascular smooth muscle, though some aspects of heart maturation (size, ANP expression) are independent of GR at these key sites.
authors.affiliation: Centre for Cardiovascular Science, University of Edinburgh, Queen’s Medical Research Institute, Edinburgh EH16 4TJ, UK.
authors.forename: Eva A
authors.initials: EA
authors.lastname: Rog-Zielinska
authors.forename: Adrian
authors.initials: A
authors.lastname: Thomson
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kenyon
authors.forename: David G
authors.initials: DG
authors.lastname: Brownstein
authors.forename: Carmel M
authors.initials: CM
authors.lastname: Moran
authors.forename: Dorota
authors.initials: D
authors.lastname: Szumska
authors.forename: Zoi
authors.initials: Z
authors.lastname: Michailidou
authors.forename: Jennifer
authors.initials: J
authors.lastname: Richardson
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Owen
authors.forename: Alistair
authors.initials: A
authors.lastname: Watt
authors.forename: Harris
authors.initials: H
authors.lastname: Morrison
authors.forename: Lesley M
authors.initials: LM
authors.lastname: Forrester
authors.forename: Shoumo
authors.initials: S
authors.lastname: Bhattacharya
authors.forename: Megan C
authors.initials: MC
authors.lastname: Holmes
authors.forename: Karen E
authors.initials: KE
authors.lastname: Chapman
mesh_terms: D000818:Animals; D003345:Corticosterone / Q000097:blood / Q000502:physiology; D005318:Fetal Heart / Q000254:growth & development* / Q000502:physiology; D005938:Glucocorticoids / Q000378:metabolism*; D006321:Heart / Q000196:embryology / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D009131:Muscle, Smooth, Vascular / Q000196:embryology / Q000378:metabolism; D009200:Myocardial Contraction; D009206:Myocardium / Q000648:ultrastructure; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism; D009210:Myofibrils / Q000648:ultrastructure; D011965:Receptors, Glucocorticoid / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D005938:Glucocorticoids; C575863:NR3C1 protein, mouse; D011965:Receptors, Glucocorticoid; D003345:Corticosterone