Myocardial specificity for initiating endothelial-mesenchymal cell transition in embryonic chick heart correlates with a particulate distribution of fibronectin

Mjaatvedt, Corey H.; Lepera, R.; Markwald, Roger R.

doi:10.1016/0012-1606(87)90206-5

Cited by 149 publications

(89 citation statements)

References 15 publications

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“…The most likely explanation for this is local secretion from the underlying specialized myocardial layer into the cushions. The myocardial layer has been shown to be the source of EC matrix components (Krug et al, 1985;Mjaatvedt et al, 1987). Following the transformation and expansion of the cushions around day 13.5, apoJ expression appears in a new population of non-myocytes situated directly beneath the endocardium.…”

Section: Discussionmentioning

confidence: 99%

“…We favor the latter possibility. An extracellular matrix complex has been shown to be required for mesenchymal transformation (Markwald et al, 1975(Markwald et al, , 1977Mjaatvedt et al, 1987;Mjaatvedt and Markwald, 1989;Sinning et al, 1992) and a p d protein has a demonstrated ability to bind to the extracellular matrix components fibronectin and heparin (Han et al, 1991;Millis et al, 1985). Identification of a p d as a developmentally regulated gene product associated with the formation of valvular structures should aid in ultimately understanding how this process occurs.…”

Section: Discussionmentioning

confidence: 99%

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Temporally and spatially restricted expression of apolipoprotein J in the developing heart defines discrete stages of valve morphogenesis

Witte

Aronow

Dry

et al. 1994

Developmental Dynamics

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During cardiac valve morphogenesis, a series of interactions between the mesodermal-derived myocardium and the overlying endothelium lead to condensed leaflet structure formation. At the atrioventricular (AV) canal, endocardial cells are transformed by specialized underlying myocardial cells into endocardial cushions, and then remodeled into mitral and tricuspid valves. Aortic and pulmonary valves develop by a similar mechanism in the primitive outflow tract. Few genes exhibit restricted spatiotemporal expression in these critical embryonic structures, thus limiting the clues to the sequence of molecular events necessary for valvulogenesis. Apolipoprotein J (ApoJ), a secreted glycoprotein expressed in a variety of cell types at tissue interfaces, exhibits a highly restricted and dynamic expression pattern in the developing heart. ApoJ transcripts were detected in mice at day 9.0 of gestation in the wall of the developing truncus arteriosus. By day 10, intense signal occurred in a thin layer of myocardial cells adjacent to developing endocardial cushions of both atrioventricular canal and truncus arteriosus. No apoJ mRNA was present in the overlying endocardial cushions until day 13.5 when prevalvular condensation begins. Intense expression occurred in the stromal connective tissue throughout leaflet formation. The highly restricted spatiotemporal expression pattern of apo J in the developing heart implicates its role in the morphogenesis of the AV canal and outflow tract into cardiac valves. 0 1994 Wiley-Liss, Inc.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Temporally and spatially restricted expression of apolipoprotein J in the developing heart defines discrete stages of valve morphogenesis

Witte

Aronow

Dry

et al. 1994

Developmental Dynamics

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“…In the interval between stages 15 and 17, a complex inductive stimulus is produced by the myocardium and secreted into the extracellular matrix of the cardiac cushions (Krug et al, 1985(Krug et al, , 1987Mjaatvedt et al, 1987). At stage 17, endothelial cells of the AVC are activated in response to this stimulus and are observed to hypertrophy, separate, and extend filopodia into the underlying ECM (Markwald et al, 1978;Kinsella and Fitzharris, 1980;Mjaatvedt and Markwald, 1989).…”

Section: Rhoa Is Expressed In the Atrioventricular Canal Of The Chickmentioning

confidence: 99%

TGFβ-mediated RhoA expression is necessary for epithelial-mesenchymal transition in the embryonic chick heart

et al. 2006

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Endothelia in the atrioventricular canal (AVC) of the embryonic heart undergo an epithelial-mesenchymal transition (EMT) and migrate into the underlying extracellular matrix. We explore here whether RhoA mediates this EMT. RhoA was detected in all cells of the chick heart during the stages studied. Expression was elevated when EMT was actively occurring. Explants treated with C3 exoenzyme in collagen gel cultures showed a significant decrease in mesenchymal cell numbers. siRNA was used to inhibit RhoA mRNA, and both activated endothelial and mesenchymal cells decreased significantly with treatment. Loss of RhoA produced a reduction of RhoB, cyclin-b2, and ␤-catenin messages showing that these genes are regulated downstream of RhoA. In contrast, runx-2 was not reduced. Inhibition of TGF␤3 or TGF␤2 activity caused a large reduction of RhoA message. These data place RhoA in TGF␤ regulated pathways for both endothelial activation and mesenchymal invasion and demonstrate a functional requirement during EMT. Developmental Dynamics 235:1589 -1598, 2006.

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“…Furthermore, fibronectin has been implied in the migration of endocardial cushion tissue cells (Mjaatvedt et al, 1987;ffrench-Constant and Hynes, 1988;Icardo et al, 19921, and molecules such as fibrillin, emilin (Hurle et al, 1994) and other, yet uncharacterized, extracellular matrix components (Mjaatvedt et al, 1991) could also be involved.…”

Section: A6a In the Developing Heartmentioning

confidence: 99%

Expression patterns of laminin receptor splice variants α6Aβ1 and α6Bβ1 suggest different roles in mouse development

Þorsteinsdóttir

Roelen

Freund

et al. 1995

Developmental Dynamics

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The a6pl integrin is a receptor for laminins and is present from early stages of mouse embryogenesis. In the present study we determined the temporal and spatial expression of the two cytoplasmic splice variants of the a6 integrin subunit, a6A and a6B, in the early-and midgestation mouse postimplantation embryo using RT-PCR, in situ hybridization, and immunofluorescence. Our results show that a6B is present in the embryo at all stages studied and is expressed before a6A. a6A expression begins in 8.5 day p.c. embryos and is initially exclusively localized to the developing heart. In 8.5 (and 9.5) day p.c. embryos a6A mRNA and protein are present in a gradient in the myocardium of the heart tube from strongest expression in the sinus venosus and in the common atrial chamber to a weakening expression along the ventricle and bulbus cordis. In 10.5 day p.c. embryos this gradient is less evident and in 12.5 day p.c. embryos a6A mRNA and protein are present in comparable amounts between atria and ventricles. Neither a6A nor a6B is present in endocardial cushion tissue. By day 12.5 p.c. (w6A expression is also present in the developing epidermis, dental primordia, lens, gonads, and in a few epithelia such as those of the digestive tract. a6B expression is always much more widespread than a6A expression. For example, only a6B is present in the myotome of the somites of 9.5 day p.c, embryos, in the developing central and peripheral nervous systems, and in the nephrogenic system at all stages studied, except after the differentiation of the gonads when a6A is also present. Furthermore, a6B is the only splice variant present on endothelial cells. We also examined the distribution of the f34 integrin subunit to determine whether the a6P4 integrin was present during these stages of development. p4 protein was absent in early postimplantation stages but was present in the epidermis and digestive tract of 12.5 day p.c. embryos. These results show a differential distribution of a6A and a6B during mouse development and thus strongly suggest a different function of these splice variants during embryogenesis. Our results point to a possible role for the 0 1995 WILEY-LISS, INC. a6Apl integrin in the development of the myocardium of the developing heart, but not in the migration of endocardial cushion cells, while a6Bp1 could be important in the developing nephrogenic and nervous systems. o l W 5 Wiley-Liss, Inc.

show abstract

Myocardial specificity for initiating endothelial-mesenchymal cell transition in embryonic chick heart correlates with a particulate distribution of fibronectin

Cited by 149 publications

References 15 publications

Temporally and spatially restricted expression of apolipoprotein J in the developing heart defines discrete stages of valve morphogenesis

Temporally and spatially restricted expression of apolipoprotein J in the developing heart defines discrete stages of valve morphogenesis

TGFβ-mediated RhoA expression is necessary for epithelial-mesenchymal transition in the embryonic chick heart

Expression patterns of laminin receptor splice variants α6Aβ1 and α6Bβ1 suggest different roles in mouse development

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