Secondary palate fusion requires adhesion and epithelial-to-mesenchymal transition (EMT) of the epithelial layers on opposing palatal shelves. This EMT requires transforming growth factor b3 (TGFb3), and its failure results in cleft palate. Ephrins, and their receptors, the Ephs, are responsible for migration, adhesion, and midline closure events throughout development. Ephrins can also act as signal-transducing receptors in these processes, with the Ephs serving as ligands (termed ''reverse'' signaling). We found that activation of ephrin reverse signaling in chicken palates induced fusion in the absence of TGFb3, and that PI3K inhibition abrogated this effect. Further, blockage of reverse signaling inhibited TGFb3-induced fusion in the chicken and natural fusion in the mouse. Thus, ephrin reverse signaling is necessary and sufficient to induce palate fusion independent of TGFb3. These data describe both a novel role for ephrins in palate morphogenesis, and a previously unknown mechanism of ephrin signaling. Developmental Dynamics 240:357-364,

Objective-To discover genes differentially expressed in the perichondrium of the mandibular condylar cartilage (MCC) that might enhance regenerative medicine or orthopedic therapies directed at the tissues of the temporomandibular joint Design-We used targeted gene arrays (osteogenesis, stem cell) to identify genes preferentially expressed in the perichondrium (PC) and the cartilaginous (C) portions of the MCC in 2 day-old mice

The development of the head involves the interaction of several cell populations and coordination of cell signalling pathways, which when disrupted can cause defects such as facial clefts. This review concentrates on genetic contributions to facial clefts with and without cleft palate (CP). An overview of early palatal development with emphasis on muscle and bone development is blended with the effects of environmental insults and known genetic mutations that impact human palatal development. An extensive table of known genes in syndromic and non-syndromic CP, with or without cleft lip (CL), is provided. We have also included some genes that have been identified in environmental risk factors for CP/L. We include primary and review references on this topic.

The mammalian secondary palate forms from shelves of epithelia-covered mesenchyme that meet at midline and fuse. The midline epithelial seam (MES) is thought to degrade by apoptosis, epithelial-to-mesenchymal transition (EMT), or both. Failure to degrade the MES blocks fusion and causes cleft palate. It was previously thought that transforming growth factor ß3 (Tgfß3) is required to initiate fusion. Members of the Eph tyrosine kinase receptor family and their membrane-bound ephrin ligands are expressed on the MES. We demonstrated that treatment of mouse palates with recombinant EphB2/Fc to activate ephrin reverse signaling (where the ephrin acts as a receptor and transduces signals from its cytodomain) was sufficient to cause mouse palatal fusion when Tgfß3 signaling was blocked by an antibody against Tgfß3 or by an inhibitor of the TgfßrI serine/threonine receptor kinase. Cultured palatal epithelial cells traded their expression of epithelial cell markers for that of mesenchymal cells and became motile after treatment with EphB2/Fc. They concurrently increased their expression of the EMT-associated transcription factors Snail, Sip1, and Twist1. EphB2/Fc did not cause apoptosis in these cells. These data reveal that ephrin reverse signaling directs palatal fusion in mammals through a mechanism that involves EMT but not apoptosis and activates a gene expression program not previously associated with ephrin reverse signaling.