Amino acid transport in mouse blastocyst compartments

Properties of uptake and exchange of L-methionine associated with the compartments of the blastocyst were examined in the mouse embryo. The inner cell mass (ICM) was derived from the 102 h blastocyst by immunosurgical procedures and studied in isolation. The ICM possessed strong exchange and efflux transport character. The Vmax of transport was about one-fifth that of the intact blastocyst, but the Km (660 µM) was about 30 times as high as that of the intact blastocyst. Consequently, at a concentration of about 1OO µM-methionine, the velocity of uptake into the ICM is about one-thirtieth of that into the intact blastocyst. Uptake of amino acid into the intact blastocyst was resolved into cellular and cavity components by mechanically collapsing the blastocyst following uptake of radiolabelled methionine. By this method, it was found that about 70% of the label accumulated by the blastocyst was in the cavity.

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Amino Acid Transport and Metabolism Regulate Early Embryo Development: Species Differences, Clinical Significance, and Evolutionary Implications

Cells ◽

10.3390/cells10113154 ◽

2021 ◽

Vol 10 (11) ◽

pp. 3154

Author(s):

Lon J. Van Van Winkle

Keyword(s):

Amino Acid ◽

Health Outcomes ◽

Embryo Development ◽

Amino Acid Transport ◽

Inner Cell Mass ◽

Cell Mass ◽

Subsequent Development ◽

Transport Systems ◽

Acid Transport ◽

Leucine Uptake

In this review we discuss the beneficial effects of amino acid transport and metabolism on pre- and peri-implantation embryo development, and we consider how disturbances in these processes lead to undesirable health outcomes in adults. Proline, glutamine, glycine, and methionine transport each foster cleavage-stage development, whereas leucine uptake by blastocysts via transport system B0,+ promotes the development of trophoblast motility and the penetration of the uterine epithelium in mammalian species exhibiting invasive implantation. (Amino acid transport systems and transporters, such as B0,+, are often oddly named. The reader is urged to focus on the transporters’ functions, not their names.) B0,+ also accumulates leucine and other amino acids in oocytes of species with noninvasive implantation, thus helping them to produce proteins to support later development. This difference in the timing of the expression of system B0,+ is termed heterochrony—a process employed in evolution. Disturbances in leucine uptake via system B0,+ in blastocysts appear to alter the subsequent development of embryos, fetuses, and placentae, with undesirable consequences for offspring. These consequences may include greater adiposity, cardiovascular dysfunction, hypertension, neural abnormalities, and altered bone growth in adults. Similarly, alterations in amino acid transport and metabolism in pluripotent cells in the blastocyst inner cell mass likely lead to epigenetic DNA and histone modifications that produce unwanted transgenerational health outcomes. Such outcomes might be avoided if we learn more about the mechanisms of these effects.

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Use of F9 teratocarcinoma STEM cells to study cell-matrix interactions in the early mouse embryo

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123416 ◽

1992 ◽

Vol 50 (1) ◽

pp. 602-603

Author(s):

Marc Lenburg ◽

Rulang Jiang ◽

Lengya Cheng ◽

Laura Grabel

Keyword(s):

Mouse Embryo ◽

Inner Cell Mass ◽

Cell Mass ◽

Cell Types ◽

Embryoid Bodies ◽

F9 Cells ◽

Cell Matrix ◽

Matrix Interactions ◽

Cell Matrix Interactions ◽

F9 Teratocarcinoma

We are interested in defining the cell-cell and cell-matrix interactions that help direct the differentiation of extraembryonic endoderm in the peri-implantation mouse embryo. At the blastocyst stage the mouse embryo consists of an outer layer of trophectoderm surrounding the fluid-filled blastocoel cavity and an eccentrically located inner cell mass. On the free surface of the inner cell mass, facing the blastocoel cavity, a layer of primitive endoderm forms. Primitive endoderm then generates two distinct cell types; parietal endoderm (PE) which migrates along the inner surface of the trophectoderm and secretes large amounts of basement membrane components as well as tissue-type plasminogen activator (tPA), and visceral endoderm (VE), a columnar epithelial layer characterized by tight junctions, microvilli, and the synthesis and secretion of α-fetoprotein. As these events occur after implantation, we have turned to the F9 teratocarcinoma system as an in vitro model for examining the differentiation of these cell types. When F9 cells are treated in monolayer with retinoic acid plus cyclic-AMP, they differentiate into PE. In contrast, when F9 cells are treated in suspension with retinoic acid, they form embryoid bodies (EBs) which consist of an outer layer of VE and an inner core of undifferentiated stem cells. In addition, we have established that when VE containing embryoid bodies are plated on a fibronectin coated substrate, PE migrates onto the matrix and this interaction is inhibited by RGDS as well as antibodies directed against the β1 integrin subunit. This transition is accompanied by a significant increase in the level of tPA in the PE cells. Thus, the outgrowth system provides a spatially appropriate model for studying the differentiation and migration of PE from a VE precursor.

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