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Leptin affects endocardial cushion formation by modulating EMT and migration via Akt signaling cascades.

Nath AK, Brown RM, Michaud M, Sierra-Honigmann MR, Snyder M, Madri JA - J. Cell Biol. (2008)

Bottom Line: Blood circulation is dependent on heart valves to direct blood flow through the heart and great vessels.Abnormal EMT and remodeling contribute to the etiology of several congenital heart defects.Our data suggest that an Akt signaling pathway underlies the observed phenotype.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, School of Medicine, Yale University, New Haven, CT 06510, USA.

ABSTRACT
Blood circulation is dependent on heart valves to direct blood flow through the heart and great vessels. Valve development relies on epithelial to mesenchymal transition (EMT), a central feature of embryonic development and metastatic cancer. Abnormal EMT and remodeling contribute to the etiology of several congenital heart defects. Leptin and its receptor were detected in the mouse embryonic heart. Using an ex vivo model of cardiac EMT, the inhibition of leptin results in a signal transducer and activator of transcription 3 and Snail/vascular endothelial cadherin-independent decrease in EMT and migration. Our data suggest that an Akt signaling pathway underlies the observed phenotype. Furthermore, loss of leptin phenocopied the functional inhibition of alphavbeta3 integrin receptor and resulted in decreased alphavbeta3 integrin and matrix metalloprotease 2, suggesting that the leptin signaling pathway is involved in adhesion and migration processes. This study adds leptin to the repertoire of factors that mediate EMT and, for the first time, demonstrates a role for the interleukin 6 family in embryonic EMT.

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Related in: MedlinePlus

Effects of leptin, STAT3, and Akt inhibition on EMT in the endocardial cushions. Quantification of endocardial (black bars) and mesenchymal cell numbers (gray bars) after AVCs were cultured with 5 μg/ml IgG or α-leptin antibody (A), vehicle or 1 mM PpYLKTK (D), and DMSO or 5 μM Akt inhibitor XI (G). Cellular morphology was evaluated by F-actin staining (red): IgG (B), α-leptin antibody (C), vehicle (E), PpYLKTK (F), DMSO (H), and Akt inhibitor XI (I). Vimentin staining after treatment with IgG (J), α-leptin antibody (K), DMSO (L), and Akt inhibitor XI (M). DAPI, blue. Error bars represent SD. *, P < 0.05.
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fig3: Effects of leptin, STAT3, and Akt inhibition on EMT in the endocardial cushions. Quantification of endocardial (black bars) and mesenchymal cell numbers (gray bars) after AVCs were cultured with 5 μg/ml IgG or α-leptin antibody (A), vehicle or 1 mM PpYLKTK (D), and DMSO or 5 μM Akt inhibitor XI (G). Cellular morphology was evaluated by F-actin staining (red): IgG (B), α-leptin antibody (C), vehicle (E), PpYLKTK (F), DMSO (H), and Akt inhibitor XI (I). Vimentin staining after treatment with IgG (J), α-leptin antibody (K), DMSO (L), and Akt inhibitor XI (M). DAPI, blue. Error bars represent SD. *, P < 0.05.

Mentions: The effects of leptin neutralization on EMT were evaluated by the addition of 5–20 μg/ml leptin antibody or isotype control IgG to the media bathing the explants. Leptin sequestration resulted in a significant decrease (∼60%) in the total number of cells on and in the collagen gel compared with IgG control (136.0 ± 18.2 vs. 320.4 ± 53.6; P = 0.001; Fig. 3 A), suggesting a defect in the commitment to undergo EMT. These cells display phenotypic activation (loss of cell–cell junctions and separation between cells). However, the percentage of total cells that undergo EMT decreased to 23% with leptin antibody treatment compared with 67% of IgG control (number of mesenchymal cells = 32.6 ± 8.6 vs. 214.0 ± 30.9; P = 0.0002; Fig. 3 A, gray bars).


Leptin affects endocardial cushion formation by modulating EMT and migration via Akt signaling cascades.

Nath AK, Brown RM, Michaud M, Sierra-Honigmann MR, Snyder M, Madri JA - J. Cell Biol. (2008)

Effects of leptin, STAT3, and Akt inhibition on EMT in the endocardial cushions. Quantification of endocardial (black bars) and mesenchymal cell numbers (gray bars) after AVCs were cultured with 5 μg/ml IgG or α-leptin antibody (A), vehicle or 1 mM PpYLKTK (D), and DMSO or 5 μM Akt inhibitor XI (G). Cellular morphology was evaluated by F-actin staining (red): IgG (B), α-leptin antibody (C), vehicle (E), PpYLKTK (F), DMSO (H), and Akt inhibitor XI (I). Vimentin staining after treatment with IgG (J), α-leptin antibody (K), DMSO (L), and Akt inhibitor XI (M). DAPI, blue. Error bars represent SD. *, P < 0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2315681&req=5

fig3: Effects of leptin, STAT3, and Akt inhibition on EMT in the endocardial cushions. Quantification of endocardial (black bars) and mesenchymal cell numbers (gray bars) after AVCs were cultured with 5 μg/ml IgG or α-leptin antibody (A), vehicle or 1 mM PpYLKTK (D), and DMSO or 5 μM Akt inhibitor XI (G). Cellular morphology was evaluated by F-actin staining (red): IgG (B), α-leptin antibody (C), vehicle (E), PpYLKTK (F), DMSO (H), and Akt inhibitor XI (I). Vimentin staining after treatment with IgG (J), α-leptin antibody (K), DMSO (L), and Akt inhibitor XI (M). DAPI, blue. Error bars represent SD. *, P < 0.05.
Mentions: The effects of leptin neutralization on EMT were evaluated by the addition of 5–20 μg/ml leptin antibody or isotype control IgG to the media bathing the explants. Leptin sequestration resulted in a significant decrease (∼60%) in the total number of cells on and in the collagen gel compared with IgG control (136.0 ± 18.2 vs. 320.4 ± 53.6; P = 0.001; Fig. 3 A), suggesting a defect in the commitment to undergo EMT. These cells display phenotypic activation (loss of cell–cell junctions and separation between cells). However, the percentage of total cells that undergo EMT decreased to 23% with leptin antibody treatment compared with 67% of IgG control (number of mesenchymal cells = 32.6 ± 8.6 vs. 214.0 ± 30.9; P = 0.0002; Fig. 3 A, gray bars).

Bottom Line: Blood circulation is dependent on heart valves to direct blood flow through the heart and great vessels.Abnormal EMT and remodeling contribute to the etiology of several congenital heart defects.Our data suggest that an Akt signaling pathway underlies the observed phenotype.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, School of Medicine, Yale University, New Haven, CT 06510, USA.

ABSTRACT
Blood circulation is dependent on heart valves to direct blood flow through the heart and great vessels. Valve development relies on epithelial to mesenchymal transition (EMT), a central feature of embryonic development and metastatic cancer. Abnormal EMT and remodeling contribute to the etiology of several congenital heart defects. Leptin and its receptor were detected in the mouse embryonic heart. Using an ex vivo model of cardiac EMT, the inhibition of leptin results in a signal transducer and activator of transcription 3 and Snail/vascular endothelial cadherin-independent decrease in EMT and migration. Our data suggest that an Akt signaling pathway underlies the observed phenotype. Furthermore, loss of leptin phenocopied the functional inhibition of alphavbeta3 integrin receptor and resulted in decreased alphavbeta3 integrin and matrix metalloprotease 2, suggesting that the leptin signaling pathway is involved in adhesion and migration processes. This study adds leptin to the repertoire of factors that mediate EMT and, for the first time, demonstrates a role for the interleukin 6 family in embryonic EMT.

Show MeSH
Related in: MedlinePlus