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Disrupted Slit-Robo signalling results in membranous ventricular septum defects and bicuspid aortic valves.

Mommersteeg MT, Yeh ML, Parnavelas JG, Andrews WD - Cardiovasc. Res. (2015)

Bottom Line: Loss of Robo1 or both Robo1 and Robo2 resulted in membranous ventricular septum defects at birth, a defect also found in Slit3, but not in Slit2 mutants.Expression of Notch- and downstream Hey and Hes genes was down-regulated in Robo1 mutants, suggesting that reduced Notch signalling in mice lacking Robo might underlie the defects.Luciferase assays confirmed regulation of Notch signalling by Robo.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Developmental Biology, University College London, 21 University Street, London WC1E 6DE, UK m.mommersteeg@ucl.ac.uk.

No MeSH data available.


Related in: MedlinePlus

Slit and Robo expression patterns in and surrounding the cardiac cushions. (A–L) immunohistochemistry (Robo1, Robo2, and Slit2-GFP), DAPI, and in situ hybridization (Slit3) staining at E12.5 in the outflow tract and atrioventricular cushion regions. Red arrowheads indicate the expression of Slit2 in the endocardium lining the cushions. (E, F, K, and L) show details of Robo1 and 2 expression in the indicated cushion regions. White arrowheads point to the region where both Robo1 and Robo2 are expressed. (D and J) Green arrowheads point to Slit3 expression in the outflow tract vessels and atrial septum, while Slit3 is not detectable in the cushions. Per stage for all genes analysed, n ≥ 3 embryos. Ao, Aorta; AVC, atrioventricular canal; AVCC, atrioventricular cushion; AVCM, atrioventricular canal myocardium; GFP, green fluorescent protein; Li, liver; OFT, outflow tract; OFTC, outflow tract cushion; MVS, membranous ventricular septum; PT, pulmonary trunk; RA, right atrium; R/LV, right/left ventricle. Scale bars depict 100 µm.
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CVV040F1: Slit and Robo expression patterns in and surrounding the cardiac cushions. (A–L) immunohistochemistry (Robo1, Robo2, and Slit2-GFP), DAPI, and in situ hybridization (Slit3) staining at E12.5 in the outflow tract and atrioventricular cushion regions. Red arrowheads indicate the expression of Slit2 in the endocardium lining the cushions. (E, F, K, and L) show details of Robo1 and 2 expression in the indicated cushion regions. White arrowheads point to the region where both Robo1 and Robo2 are expressed. (D and J) Green arrowheads point to Slit3 expression in the outflow tract vessels and atrial septum, while Slit3 is not detectable in the cushions. Per stage for all genes analysed, n ≥ 3 embryos. Ao, Aorta; AVC, atrioventricular canal; AVCC, atrioventricular cushion; AVCM, atrioventricular canal myocardium; GFP, green fluorescent protein; Li, liver; OFT, outflow tract; OFTC, outflow tract cushion; MVS, membranous ventricular septum; PT, pulmonary trunk; RA, right atrium; R/LV, right/left ventricle. Scale bars depict 100 µm.

Mentions: We have previously reported the overall expression patterns of Robo1, Robo2, Slit2 and Slit3 in the murine heart and migrating cardiac neural crest.16 The presence of these genes in and surrounding the cardiac cushions prompted us to study their expression in these regions in more detail. As we have previously shown that Robo3 is not expressed inside the heart and Robo4 only in the coronary circulation, we excluded these receptors from our study. Robo1 was expressed in the outflow tract and atrioventricular cushions, and subsequently valves, as well as in the atrioventricular canal myocardium throughout embryonic development (Figure 1A, B, E, G, H, and K; see Supplementary material online, Figure S1A–H),16 the only exception being its disappearance from specifically the aortic semilunar valves just before birth (data not shown). Robo2 was never observed in the myocardium but was present in both the outflow tract and atrioventricular cushions, and later valves, all through development (Figure 1C, F, I, and L; see Supplementary material online, Figure S1A–H). In the outflow tract around E12.5, expression of Robo2 was highest in the cushion area contributing to the separation of the aortic and pulmonary outflow within the heart (Figure 1C and F; see Supplementary material online, Figure S1C).Figure 1


Disrupted Slit-Robo signalling results in membranous ventricular septum defects and bicuspid aortic valves.

Mommersteeg MT, Yeh ML, Parnavelas JG, Andrews WD - Cardiovasc. Res. (2015)

Slit and Robo expression patterns in and surrounding the cardiac cushions. (A–L) immunohistochemistry (Robo1, Robo2, and Slit2-GFP), DAPI, and in situ hybridization (Slit3) staining at E12.5 in the outflow tract and atrioventricular cushion regions. Red arrowheads indicate the expression of Slit2 in the endocardium lining the cushions. (E, F, K, and L) show details of Robo1 and 2 expression in the indicated cushion regions. White arrowheads point to the region where both Robo1 and Robo2 are expressed. (D and J) Green arrowheads point to Slit3 expression in the outflow tract vessels and atrial septum, while Slit3 is not detectable in the cushions. Per stage for all genes analysed, n ≥ 3 embryos. Ao, Aorta; AVC, atrioventricular canal; AVCC, atrioventricular cushion; AVCM, atrioventricular canal myocardium; GFP, green fluorescent protein; Li, liver; OFT, outflow tract; OFTC, outflow tract cushion; MVS, membranous ventricular septum; PT, pulmonary trunk; RA, right atrium; R/LV, right/left ventricle. Scale bars depict 100 µm.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4362403&req=5

CVV040F1: Slit and Robo expression patterns in and surrounding the cardiac cushions. (A–L) immunohistochemistry (Robo1, Robo2, and Slit2-GFP), DAPI, and in situ hybridization (Slit3) staining at E12.5 in the outflow tract and atrioventricular cushion regions. Red arrowheads indicate the expression of Slit2 in the endocardium lining the cushions. (E, F, K, and L) show details of Robo1 and 2 expression in the indicated cushion regions. White arrowheads point to the region where both Robo1 and Robo2 are expressed. (D and J) Green arrowheads point to Slit3 expression in the outflow tract vessels and atrial septum, while Slit3 is not detectable in the cushions. Per stage for all genes analysed, n ≥ 3 embryos. Ao, Aorta; AVC, atrioventricular canal; AVCC, atrioventricular cushion; AVCM, atrioventricular canal myocardium; GFP, green fluorescent protein; Li, liver; OFT, outflow tract; OFTC, outflow tract cushion; MVS, membranous ventricular septum; PT, pulmonary trunk; RA, right atrium; R/LV, right/left ventricle. Scale bars depict 100 µm.
Mentions: We have previously reported the overall expression patterns of Robo1, Robo2, Slit2 and Slit3 in the murine heart and migrating cardiac neural crest.16 The presence of these genes in and surrounding the cardiac cushions prompted us to study their expression in these regions in more detail. As we have previously shown that Robo3 is not expressed inside the heart and Robo4 only in the coronary circulation, we excluded these receptors from our study. Robo1 was expressed in the outflow tract and atrioventricular cushions, and subsequently valves, as well as in the atrioventricular canal myocardium throughout embryonic development (Figure 1A, B, E, G, H, and K; see Supplementary material online, Figure S1A–H),16 the only exception being its disappearance from specifically the aortic semilunar valves just before birth (data not shown). Robo2 was never observed in the myocardium but was present in both the outflow tract and atrioventricular cushions, and later valves, all through development (Figure 1C, F, I, and L; see Supplementary material online, Figure S1A–H). In the outflow tract around E12.5, expression of Robo2 was highest in the cushion area contributing to the separation of the aortic and pulmonary outflow within the heart (Figure 1C and F; see Supplementary material online, Figure S1C).Figure 1

Bottom Line: Loss of Robo1 or both Robo1 and Robo2 resulted in membranous ventricular septum defects at birth, a defect also found in Slit3, but not in Slit2 mutants.Expression of Notch- and downstream Hey and Hes genes was down-regulated in Robo1 mutants, suggesting that reduced Notch signalling in mice lacking Robo might underlie the defects.Luciferase assays confirmed regulation of Notch signalling by Robo.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Developmental Biology, University College London, 21 University Street, London WC1E 6DE, UK m.mommersteeg@ucl.ac.uk.

No MeSH data available.


Related in: MedlinePlus