In the early 19th century, building on observations of microscopists now ancient, Schleiden and Schwann formulated the doctrine that cells are building blocks for plant and animal tissues (1). By the mid-19th century, Raspail, Remak, and Virchow expanded this hypothesis by suggesting that all cells come from preexisting cells — the so-called cell theory. Although referring to cell division, this now classic notion is prescient of another contemporary twist in the biology of cell maturation: beyond lineage development and normal differentiation, mature epithelial cells under new environmental pressures exhibit a local plasticity that allows them to morph into other mature phenotypes with or without proliferation (2, 3). Growing interest in the biology of these cellular transitions helped both establish epithelial cell plasticity as a field of study in the late 20th century and fashion much of the current thinking regarding morphogenesis in early embryonic development, tissue repair, and cancer metastasis (4–6). The details of some of these processes are not discussed here, as they are outlined in other articles in this Review Series on epithelial-mesenchymal transition (EMT) (7, 8). Instead, we offer a personal view gathered from our own experience and the literature regarding an approach documenting EMT events in culture or tissue. We hope this serves to stimulate other points of view as new data emerge.

/pdf/biomarkers-for-epithelial-mesenchymal-transitions-4rugbye0ja.pdf

Biomarkers for epithelial-mesenchymal transitions

Ultrasound assisted extraction of food and natural products. Mechanisms, techniques, combinations, protocols and applications. A review.

Microbubbles in ultrasound-triggered drug and gene delivery

Epithelial-mesenchymal transition (EMT) is a crucial, evolutionarily conserved process that occurs during development and is essential for shaping embryos. Also implicated in cancer, this morphological transition is executed through multiple mechanisms in different contexts, and studies suggest that the molecular programs governing EMT, albeit still enigmatic, are embedded within developmental programs that regulate specification and differentiation. As we review here, knowledge garnered from studies of EMT during gastrulation, neural crest delamination and heart formation have furthered our understanding of tumor progression and metastasis.

/pdf/epithelial-mesenchymal-transitions-insights-from-development-2t8yhx88au.pdf

Epithelial-mesenchymal transitions: insights from development

Physical methods for gene transfer: Improving the kinetics of gene delivery into cells

In the gastrula stage embryo, the epiblast migrates toward the primitive
streak and ingresses through the primitive groove. Subsequently, the
ingressing epiblast cells undergo epithelial-mesenchymal transition (EMT) and
differentiate into the definitive endoderm and mesoderm during gastrulation.
However, the developmental mechanisms at the end of gastrulation have not yet
been elucidated. Histological and genetic analyses of the ventral ectodermal
ridge (VER), a derivative of the primitive streak, were performed using chick
and mouse embryos. The analyses showed a continued cell movement resembling
gastrulation associated with EMT during the early tailbud stage of both
embryos. Such gastrulation-like cell movement was gradually attenuated by the
absence of EMT during tail development. The kinetics of the expression pattern
of noggin ( Nog ) and basal membrane degradation adjacent to the chick
and the mouse VER indicated a correlation between the temporal and/or spatial
expression of Nog and the presence of EMT in the VER. Furthermore,
 Nog overexpression suppressed EMT and arrested ingressive cell
movement in the chick VER. Mice mutant in noggin displayed dysregulation of
EMT with continued ingressive cell movement. These indicate that the
inhibition of Bmp signaling by temporal and/or spatial Nog expression
suppresses EMT and leads to the cessation of the ingressive cell movement from
the VER at the end of gastrulation.

/pdf/cessation-of-gastrulation-is-mediated-by-suppression-of-hfgk5o2y9y.pdf

Cessation of gastrulation is mediated by suppression of epithelial-mesenchymal transition at the ventral ectodermal ridge

Summary: The gene transduction technique is a useful method to study gene functions that underlie vertebrate embryogenesis. In this study, a new gene transduction technique is reported using microbubble-enhanced sonoporation (hereafter referred to as sonoporation) to achieve ectopic and transient gene expression for several embryonic organs including embryonic chick limb bud mesenchymes. The technique proposed in this study has the advantages of 1) relatively simple gene transduction procedures, and 2) efficient exogenous gene transduction and expression with lower damages to embryos. Green fluorescent protein (GFP) or LacZ was misexpressed in limb bud mesenchymes by sonoporation, with the introduced expression transiently detected in the injected sites. Most of the transduced chick embryos survived without showing significant embryonic abnormalities or cell death after sonoporation. To demonstrate its efficacy for assessing the effect of transient gene transduction, the Shh (sonic hedgehog) was transduced into the developing chick limb bud. The transduced limb bud displayed limb malformations including partial digit duplication. Advantages and possible future applications in relation to this method are discussed. genesis 37:91–101, 2003. © 2003 Wiley-Liss, Inc.

Microbubble-enhanced sonoporation: Efficient gene transduction technique for chick embryos

Gene transduction technologies are essential tools for understanding of gene functions or gene cascades underlying embryogenesis. In this review, we introduce a gene transduction method using microbubble and ultrasound (hereafter referred to as sonoporation). Sonoporation is carried out with relatively simple procedures and easily transduces genes into mesenchymal cells without significant damage to target tissues. Therefore, sonoporation is effective for gene transduction to study the molecular mechanisms of morphogenesis.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1440-169X.2008.01026.x

Gene transduction by sonoporation

The inner ear consists of two otocyst-derived, structurally and functionally distinct components: the dorsal vestibular and ventral auditory compartments. BMP signaling is required to form the vestibular compartment, but how it complements other required signaling molecules and acts intracellularly is unknown. Using spatially and temporally controlled delivery of signaling pathway regulators to developing chick otocysts, we show that BMP signaling regulates the expression of Dlx5 and Hmx3, both of which encode transcription factors essential for vestibular formation. However, although BMP regulates Dlx5 through the canonical SMAD pathway, surprisingly, it regulates Hmx3 through a non-canonical pathway involving both an increase in cAMP-dependent protein kinase A activity and the GLI3R to GLI3A ratio. Thus, both canonical and non-canonical BMP signaling establish the precise spatiotemporal expression of Dlx5 and Hmx3 during dorsal vestibular development. The identification of the non-canonical pathway suggests an intersection point between BMP and SHH signaling, which is required for ventral auditory development.

/pdf/bmp-regulates-regional-gene-expression-in-the-dorsal-otocyst-46vwta0dyl.pdf

Sho Ohta

Papers

Cessation of gastrulation is mediated by suppression of epithelial-mesenchymal transition at the ventral ectodermal ridge

Microbubble-enhanced sonoporation: Efficient gene transduction technique for chick embryos

Gene transduction by sonoporation

BMP regulates regional gene expression in the dorsal otocyst through canonical and non-canonical intracellular pathways

BMP/SMAD signaling regulates the cell behaviors that drive the initial dorsal-specific regional morphogenesis of the otocyst.