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Vulnerability of the developing heart to oxygen deprivation as a cause of congenital heart defects.

Kenchegowda D, Liu H, Thompson K, Luo L, Martin SS, Fisher SA - J Am Heart Assoc (2014)

Bottom Line: The heart develops under reduced and varying oxygen concentrations, yet there is little understanding of oxygen metabolism in the normal and mal-development of the heart.ODD-Luc activity decreased in 2 stages, the first corresponding with the formation of a functional cardiovascular system for oxygen delivery at E15.5, and the second after birth consistent with complete oxygenation of the blood and tissues.Low oxygen concentrations and lack of oxygen reserve during a critical phase of heart organogenesis may provide a basis for vulnerability to the development of common septation and conotruncal heart defects.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, MD (D.K., S.A.F.).

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Related in: MedlinePlus

ODD‐Luc activity declines during normal development and is robustly induced by maternal O2 deprivation. Luciferase activity was measured in tissue lysates from (A) E9.5 whole embryo (B) heart and (C) liver from E10.5 to 17.5 and in the adult mouse (8 weeks). Pregnant ODD‐Luc mice from the same stages were exposed to hypoxia (8% O2 for 4 hours) and luciferase activity measured. These mice were homozygous for ODD‐Luc in the Rosa26 locus. D, Luciferase activity was measured in E13.5 and adult heart lysates from mice heterozygous for the wild‐type (WT) Luciferase in the Rosa26 locus. Luciferase activity was normalized to total protein and is expressed as mean±SEM LU/mg protein ×103. Number of samples in each group is indicated within the bar graph (n). Student t test was used for comparison of hypoxia (Hx) vs normoxia (Nx) samples. *P<0.05; **P<0.01; ***P<0.001. In the developmental series (B and C) basal luciferase activity (Nx) was analyzed by 1‐way ANOVA with Bonferroni correction for multiple comparisons; groups sharing the same symbol are not significantly different (P>0.05). For E13.5 vs E15.5 heart, P=0.06. Test for interaction between developmental stage and hypoxic induction of ODD‐Luc was performed using 2‐way ANOVA (P<0.001). LU indicates luminescence units; ODD‐Luc, oxygen degradation domain‐luciferase.
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fig01: ODD‐Luc activity declines during normal development and is robustly induced by maternal O2 deprivation. Luciferase activity was measured in tissue lysates from (A) E9.5 whole embryo (B) heart and (C) liver from E10.5 to 17.5 and in the adult mouse (8 weeks). Pregnant ODD‐Luc mice from the same stages were exposed to hypoxia (8% O2 for 4 hours) and luciferase activity measured. These mice were homozygous for ODD‐Luc in the Rosa26 locus. D, Luciferase activity was measured in E13.5 and adult heart lysates from mice heterozygous for the wild‐type (WT) Luciferase in the Rosa26 locus. Luciferase activity was normalized to total protein and is expressed as mean±SEM LU/mg protein ×103. Number of samples in each group is indicated within the bar graph (n). Student t test was used for comparison of hypoxia (Hx) vs normoxia (Nx) samples. *P<0.05; **P<0.01; ***P<0.001. In the developmental series (B and C) basal luciferase activity (Nx) was analyzed by 1‐way ANOVA with Bonferroni correction for multiple comparisons; groups sharing the same symbol are not significantly different (P>0.05). For E13.5 vs E15.5 heart, P=0.06. Test for interaction between developmental stage and hypoxic induction of ODD‐Luc was performed using 2‐way ANOVA (P<0.001). LU indicates luminescence units; ODD‐Luc, oxygen degradation domain‐luciferase.

Mentions: Luciferase activity was measured in ODD‐Luc mouse tissue homogenates throughout development as a reporter for O2‐dependent PHD activity. Activity normalized to total protein was highest in the E9.5 embryo (Figure 1A). Dissection of individual organs was not feasible at this stage due to their small size. In the embryonic heart, activity was highest at E10.5 and declined 3.5‐fold to E15.5 (P<0.001) and further decreased by 4.6‐fold between E17.5 and maturity (P<0.001; Figure 1B). The liver showed a similar pattern (Figure 1C); the activity was 2.2‐fold higher in E10.5 liver versus heart (P<0.001). The decline in activity in the liver occurred between E10.5 and 13.5. The developmental decline in luciferase activity was specific for the ODD of the modified Luciferase protein as there was no difference between E13.5 and adult heart (P=0.66) when wild type luciferase (WT‐Luc) was expressed from the Rosa26 locus (Figure 1D). Comparisons of WT‐Luc and ODD‐Luc activity suggest that ≈40% of the ODD‐Luc is degraded in E13.5 tissues versus 90% in adult tissues.


Vulnerability of the developing heart to oxygen deprivation as a cause of congenital heart defects.

Kenchegowda D, Liu H, Thompson K, Luo L, Martin SS, Fisher SA - J Am Heart Assoc (2014)

ODD‐Luc activity declines during normal development and is robustly induced by maternal O2 deprivation. Luciferase activity was measured in tissue lysates from (A) E9.5 whole embryo (B) heart and (C) liver from E10.5 to 17.5 and in the adult mouse (8 weeks). Pregnant ODD‐Luc mice from the same stages were exposed to hypoxia (8% O2 for 4 hours) and luciferase activity measured. These mice were homozygous for ODD‐Luc in the Rosa26 locus. D, Luciferase activity was measured in E13.5 and adult heart lysates from mice heterozygous for the wild‐type (WT) Luciferase in the Rosa26 locus. Luciferase activity was normalized to total protein and is expressed as mean±SEM LU/mg protein ×103. Number of samples in each group is indicated within the bar graph (n). Student t test was used for comparison of hypoxia (Hx) vs normoxia (Nx) samples. *P<0.05; **P<0.01; ***P<0.001. In the developmental series (B and C) basal luciferase activity (Nx) was analyzed by 1‐way ANOVA with Bonferroni correction for multiple comparisons; groups sharing the same symbol are not significantly different (P>0.05). For E13.5 vs E15.5 heart, P=0.06. Test for interaction between developmental stage and hypoxic induction of ODD‐Luc was performed using 2‐way ANOVA (P<0.001). LU indicates luminescence units; ODD‐Luc, oxygen degradation domain‐luciferase.
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fig01: ODD‐Luc activity declines during normal development and is robustly induced by maternal O2 deprivation. Luciferase activity was measured in tissue lysates from (A) E9.5 whole embryo (B) heart and (C) liver from E10.5 to 17.5 and in the adult mouse (8 weeks). Pregnant ODD‐Luc mice from the same stages were exposed to hypoxia (8% O2 for 4 hours) and luciferase activity measured. These mice were homozygous for ODD‐Luc in the Rosa26 locus. D, Luciferase activity was measured in E13.5 and adult heart lysates from mice heterozygous for the wild‐type (WT) Luciferase in the Rosa26 locus. Luciferase activity was normalized to total protein and is expressed as mean±SEM LU/mg protein ×103. Number of samples in each group is indicated within the bar graph (n). Student t test was used for comparison of hypoxia (Hx) vs normoxia (Nx) samples. *P<0.05; **P<0.01; ***P<0.001. In the developmental series (B and C) basal luciferase activity (Nx) was analyzed by 1‐way ANOVA with Bonferroni correction for multiple comparisons; groups sharing the same symbol are not significantly different (P>0.05). For E13.5 vs E15.5 heart, P=0.06. Test for interaction between developmental stage and hypoxic induction of ODD‐Luc was performed using 2‐way ANOVA (P<0.001). LU indicates luminescence units; ODD‐Luc, oxygen degradation domain‐luciferase.
Mentions: Luciferase activity was measured in ODD‐Luc mouse tissue homogenates throughout development as a reporter for O2‐dependent PHD activity. Activity normalized to total protein was highest in the E9.5 embryo (Figure 1A). Dissection of individual organs was not feasible at this stage due to their small size. In the embryonic heart, activity was highest at E10.5 and declined 3.5‐fold to E15.5 (P<0.001) and further decreased by 4.6‐fold between E17.5 and maturity (P<0.001; Figure 1B). The liver showed a similar pattern (Figure 1C); the activity was 2.2‐fold higher in E10.5 liver versus heart (P<0.001). The decline in activity in the liver occurred between E10.5 and 13.5. The developmental decline in luciferase activity was specific for the ODD of the modified Luciferase protein as there was no difference between E13.5 and adult heart (P=0.66) when wild type luciferase (WT‐Luc) was expressed from the Rosa26 locus (Figure 1D). Comparisons of WT‐Luc and ODD‐Luc activity suggest that ≈40% of the ODD‐Luc is degraded in E13.5 tissues versus 90% in adult tissues.

Bottom Line: The heart develops under reduced and varying oxygen concentrations, yet there is little understanding of oxygen metabolism in the normal and mal-development of the heart.ODD-Luc activity decreased in 2 stages, the first corresponding with the formation of a functional cardiovascular system for oxygen delivery at E15.5, and the second after birth consistent with complete oxygenation of the blood and tissues.Low oxygen concentrations and lack of oxygen reserve during a critical phase of heart organogenesis may provide a basis for vulnerability to the development of common septation and conotruncal heart defects.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Medicine, University of Maryland School of Medicine, Baltimore, MD (D.K., S.A.F.).

Show MeSH
Related in: MedlinePlus