BMP-2 Induces Versican and Hyaluronan That Contribute to Post-EMT AV Cushion Cell Migration

Kei Inai,Jessica L Burnside,Stanley Hoffman,Yukiko Sugi,Bryan P Toole,Thomas Brand

doi:10.1371/journal.pone.0077593

Kei Inai, Jessica L Burnside + Show 4 more

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https://doi.org/10.1371/journal.pone.0077593

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Journal: PloS one	Publication Date: Oct 11, 2013
Citations: 73	License type: CC BY 4.0

Affiliation: Medical University of South Carolina

Abstract

Distal outgrowth and maturation of mesenchymalized endocardial cushions are critical morphogenetic events during post-EMT atrioventricular (AV) valvuloseptal morphogenesis. We explored the role of BMP-2 in the regulation of valvulogenic extracellular matrix (ECM) components, versican and hyaluronan (HA), and cell migration during post-EMT AV cushion distal outgrowth/expansion. We observed intense staining of versican and HA in AV cushion mesenchyme from the early cushion expansion stage, Hamburger and Hamilton (HH) stage-17 to the cushion maturation stage, HH stage-29 in the chick. Based on this expression pattern we examined the role of BMP-2 in regulating versican and HA using 3D AV cushion mesenchymal cell (CMC) aggregate cultures on hydrated collagen gels. BMP-2 induced versican expression and HA deposition as well as mRNA expression of versican and Has2 by CMCs in a dose dependent manner. Noggin, an antagonist of BMP, abolished BMP-2-induced versican and HA as well as mRNA expression of versican and Has2. We further examined whether BMP-2-promoted cell migration was associated with expression of versican and HA. BMP-2- promoted cell migration was significantly impaired by treatments with versican siRNA and HA oligomer. In conclusion, we provide evidence that BMP-2 induces expression of versican and HA by AV CMCs and that these ECM components contribute to BMP-2-induced CMC migration, indicating critical roles for BMP-2 in distal outgrowth/expansion of mesenchymalized AV cushions.

Highlights

Cardiac valvuloseptal morphogenesis is a key morphogenetic event during formation of the four-chambered heart
HA and versican were localized in the AV cardiac jelly, whereas aggrecan expression was restricted to cartilage in the developing vertebra but not in the myocardium
Studies with Nkx2.5-cre/Bone morphogenetic protein (BMP)-2 conditional knockout (cKO) mice showed that myocardially-derived BMP-2 was essential for AV cushion formation [7,8]

Summary

Introduction

Cardiac valvuloseptal morphogenesis is a key morphogenetic event during formation of the four-chambered heart. During this process, two segments of endocardium — atrioventricular (AV) and outflow tract (OT) endocardium — transform into cushion mesenchyme through an epithelialmesenchymal transformation (EMT). After the initial formation of AV endocardial cushions at Hamburger and Hamilton (HH) stage-15 in the chick and embryonic day (ED) 9.5 in the mouse, BMP-2 ligand and Type I BMP receptors (BMPRs) are abundantly expressed in the expanding and maturing AV cushion mesenchyme [5,12,13,14]. Early lethality of the BMP-2 myocardial cKO and BMPR1A (Alk3) endocardial cKO mice at the EMT stage [7,8,9,10] prevents investigation of the roles of BMP signaling in post-EMT AV valvuloseptal morphogenesis

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