Desmosome biogenesis in the mouse preimplantation embryo

Development ◽  
1991 ◽  
Vol 112 (2) ◽  
pp. 527-539 ◽  
Author(s):  
T.P. Fleming ◽  
D.R. Garrod ◽  
A.J. Elsmore
Keyword(s):  
Preimplantation Embryo ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Contact ◽  
Cell Stage ◽  
Linear Pattern ◽  
Cell Clusters ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact

The molecular processes underlying the formation of the first desmosomes in the mouse early embryo have been examined by immunocytochemical and biochemical techniques using antibody probes recognising desmosomal proteins 1 and 2 (dp1 + 2, desmoplakins), dp3 (plakoglobin), desmosomal glycoprotein 1 (dg1, desmoglein) and dg2 + 3 (desmocollins). Immunofluorescence labelling of staged intact embryos and synchronised cell clusters indicates that dp1 + 2, dg1 and dg2 + 3 are first detectable on the lateral membrane contact sites between trophectoderm cells in early cavitating blastocysts, coincident with the onset of desmosome formation as seen in ultrastructural preparations. Membrane localisation of these antigens is predominantly punctate in appearance, occurs after division to the 32-cell stage and appears to be coincident with blastocoele formation since non-cavitated embryos/cell clusters of equivalent age/cell cycle are usually unlabelled. In contrast, dp3 is first detectable at the 32-cell stage at all internal membrane contact sites (including those with inner cell mass cells) in a continuous linear pattern, and appears in both cavitated and non-cavitated specimens. Subsequently during blastocyst expansion, dp3 localisation becomes punctate and restricted to trophectodermal membranes. Immunoprecipitation of desmosomal antigens following metabolic labelling indicates that synthesis of dp3 is underway from at least compaction in the 8-cell embryo, while dp1 + 2 synthesis is first evident in 16-cell morulae. Synthesis of dg1 and dg2 + 3 is not detectable until the early blastocyst stage. These results suggest that desmosome biogenesis in the preimplantation embryo might be regulated by transcription or translation of desmosomal glycoproteins and by maturational changes in the trophectoderm layer associated with blastocoele formation. The earlier expression and wider distribution of dp3 at cell contact areas may reflect non-desmosomal sites (eg, adherens junctions) for this protein and a possible role for dp3 in the development of intercellular junctions.

scholarly journals Tissue-specific control of expression of the tight junction polypeptide ZO-1 in the mouse early embryo

Development ◽  
1991 ◽  
Vol 113 (1) ◽  
pp. 295-304 ◽  
Author(s):  
T.P. Fleming ◽  
M.J. Hay
Keyword(s):  
Tight Junction ◽  
Contact Area ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Subsequent Development ◽  
Early Embryo ◽  
Cell Contact ◽  
Down Regulation ◽  
Cell Stage ◽  
Daughter Cells

The processes governing differential protein expression in preimplantation lineages were investigated using a monoclonal antibody recognising the tight junction polypeptide, ZO-1. ZO-1 localises to the maturing tight junction membrane domain in the polarised trophectoderm lineage from compaction (8-cell stage) onwards, ultimately forming a zonular belt around each trophectoderm cell of the blastocyst (32- to 64-cell stage). The protein is usually undetectable within the inner cell mass (ICM) although, in a minority of embryos, punctate ZO-1 sites are present on the surface of one or more ICM cells. Since ICM cells derive from the differentiative division of polarised 8- and 16-cell blastomeres, the distribution of ZO-1 following differentiative division in isolated, synchronised cell clusters of varying size, was examined. In contrast to the apical cytocortical pole, ZO-1 was found to be inherited by nonpolar (prospective ICM) as well as polar (prospective trophectoderm) daughter cells. Following division, polar cells adhere to and gradually envelop nonpolar cells. Prior to envelopment, ZO-1 localises to the boundary between the contact area and free membrane of daughter cells, irrespective of their phenotype. After envelopment, polar cells retain these ZO-1 contact sites whilst nonpolar cells lose them, in which case ZO-1 transiently appears as randomly-distributed punctate sites on the membrane before disappearing. Thus, symmetrical cell contact appears to initiate ZO-1 down-regulation in the ICM lineage. The biosynthetic level at which ZO-1 down-regulation occurs was investigated in immunosurgically isolated ICMs undergoing trophectoderm regeneration. By 6 h in culture, isolated ICMs generated a zonular network of ZO-1 at the contact area between outer cells, thereby demonstrating the reversibility of down-regulation. This assembly process was unaffected by alpha-amanitin treatment but was inhibited by cycloheximide. These results indicate that the ICM inherits and stabilises ZO-1 transcripts which can be utilised for rapid synthesis and assembly of the protein, a capacity that may have significance both in maintaining lineage integrity within the blastocyst and in the subsequent development of the ICM.

scholarly journals Changes in the distribution of a spectrin-like protein during development of the preimplantation mouse embryo.

1985 ◽  
Vol 100 (1) ◽  
pp. 333-336 ◽  
Author(s):  
J S Sobel ◽  
M A Alliegro
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Contact ◽  
Apical Region ◽  
Cell Stage ◽  
Preimplantation Mouse Embryo ◽  
Preimplantation Mouse ◽  
Alpha Spectrin ◽  
Avian Erythrocyte ◽  
Cell Cell

The mouse blastocyst expresses a 240,000-mol-wt polypeptide that cross-reacts with antibody to avian erythrocyte alpha-spectrin. Immunofluorescence localization showed striking changes in the distribution of the putative embryonic spectrin during preimplantation and early postimplantation development. There was no detectable spectrin in either the unfertilized or fertilized egg. The first positive reaction was observed in the early 2-cell stage when a bright band of fluorescence delimited the region of cell-cell contact. The blastomeres subsequently developed continuous cortical layers of spectrin and this distribution was maintained throughout the cleavage stages. A significant reduction in fluorescence intensity occurred before implantation in the apical region of the mural trophoblast and the trophoblast outgrowths developed linear arrays of spectrin spots that were oriented in the direction of spreading. In contrast to the alterations that take place in the periphery of the embryo, spectrin was consistently present in the cortical cytoplasm underlying regions of contact between the blastomeres and between cells of the inner cell mass. The results suggest a possible role for spectrin in cell-cell interactions during early development.

scholarly journals Gene expression in the mouse preimplantation embryo

Reproduction ◽  
2003 ◽  
pp. 457-468 ◽  
Author(s):  
JA Stanton ◽  
AB Macgregor ◽  
DP Green
Keyword(s):  
Gene Expression ◽  
Preimplantation Embryo ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Preimplantation Development ◽  
National Institutes Of Health ◽  
Cell Stage ◽  
Cdna Sequences ◽  
Starting Point ◽  
Mouse Preimplantation Embryo

Mouse preimplantation development represents a tightly controlled programme of gene expression and cell division, which starts with the fertilized egg and ends with implantation of the blastocyst approximately 4.5 days later. Spatial and temporal differences in gene expression underpin establishment of axes at the two-cell stage and development of the trophectoderm and inner cell mass after embryo compaction at the eight-cell stage. Approximately 15 700 mouse genes expressed during preimplantation development have been identified from cDNA sequences deposited in the UniGene database of the National Institutes of Health. This inventory of preimplantation genes is the starting point for identifying signalling modules that function in preimplantation development.

scholarly journals Totipotency of mouse zygotes extends to single blastomeres of embryos at the four-cell stage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marino Maemura ◽  
Hiroaki Taketsuru ◽  
Yuki Nakajima ◽  
Ruiqi Shao ◽  
Ayaka Kakihara ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Mouse Embryos ◽  
Primitive Endoderm ◽  
Cell Stage ◽  
Supportive Environment ◽  
Mouse Zygotes ◽  
Single Blastomeres ◽  
Multicellular Organisms

AbstractIn multicellular organisms, oocytes and sperm undergo fusion during fertilization and the resulting zygote gives rise to a new individual. The ability of zygotes to produce a fully formed individual from a single cell when placed in a supportive environment is known as totipotency. Given that totipotent cells are the source of all multicellular organisms, a better understanding of totipotency may have a wide-ranging impact on biology. The precise delineation of totipotent cells in mammals has remained elusive, however, although zygotes and single blastomeres of embryos at the two-cell stage have been thought to be the only totipotent cells in mice. We now show that a single blastomere of two- or four-cell mouse embryos can give rise to a fertile adult when placed in a uterus, even though blastomere isolation disturbs the transcriptome of derived embryos. Single blastomeres isolated from embryos at the eight-cell or morula stages and cultured in vitro manifested pronounced defects in the formation of epiblast and primitive endoderm by the inner cell mass and in the development of blastocysts, respectively. Our results thus indicate that totipotency of mouse zygotes extends to single blastomeres of embryos at the four-cell stage.

scholarly journals Caenorhabditis elegans Junctophilin has tissue-specific functions and regulates neurotransmission with extended-synaptotagmin

Genetics ◽  
2021 ◽  
Author(s):  
Christopher A Piggott ◽  
Zilu Wu ◽  
Stephen Nurrish ◽  
Suhong Xu ◽  
Joshua M Kaplan ◽  
...  
Keyword(s):  
Calcium Channels ◽  
Calcium Channel ◽  
Tissue Specific ◽  
Voltage Gated ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Pharyngeal Muscles ◽  
Membrane Contact ◽  
Null Mutants

Abstract The junctophilin family of proteins tether together plasma membrane (PM) and endoplasmic reticulum (ER) membranes, and couple PM- and ER-localized calcium channels. Understanding in vivo functions of junctophilins is of great interest for dissecting the physiological roles of ER-PM contact sites. Here, we show that the sole C. elegans junctophilin JPH-1 localizes to discrete membrane contact sites in neurons and muscles and has important tissue-specific functions. jph-1 null mutants display slow growth and development due to weaker contraction of pharyngeal muscles, leading to reduced feeding. In the body wall muscle, JPH-1 co-localizes with the PM-localized EGL-19 voltage-gated calcium channel and ER-localized UNC-68/RyR calcium channel, and is required for animal movement. In neurons, JPH-1 co-localizes with the membrane contact site protein Extended-SYnaptoTagmin 2 (ESYT-2) in soma, and is present near presynaptic release sites. Interestingly, jph-1 and esyt-2 null mutants display mutual suppression in their response to aldicarb, suggesting that JPH-1 and ESYT-2 have antagonistic roles in neuromuscular synaptic transmission. Additionally, we find an unexpected cell non-autonomous effect of jph-1 in axon regrowth after injury. Genetic double mutant analysis suggests that jph-1 functions in overlapping pathways with two PM-localized voltage-gated calcium channels, egl-19 and unc-2, and unc-68/RyR for animal health and development. Finally, we show that jph-1 regulates the colocalization of EGL-19 and UNC-68 and that unc-68/RyR is required for JPH-1 localization to ER-PM puncta. Our data demonstrate important roles for junctophilin in cellular physiology, and also provide insights into how junctophilin functions together with other calcium channels in vivo.

scholarly journals Remodelling of Nucleus-Vacuole Junctions During Metabolic and Proteostatic Stress

Contact ◽  
2021 ◽  
Vol 4 ◽  
pp. 251525642110166
Author(s):  
Verena Kohler ◽  
Sabrina Büttner
Keyword(s):  
Nuclear Envelope ◽  
Internal Stress ◽  
Molecular Architecture ◽  
Adaptation To Stress ◽  
Semipermeable Membranes ◽  
Cellular Adaptation ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Intracellular Compartments ◽  
Membrane Contact

Cellular adaptation to stress and metabolic cues requires a coordinated response of different intracellular compartments, separated by semipermeable membranes. One way to facilitate interorganellar communication is via membrane contact sites, physical bridges between opposing organellar membranes formed by an array of tethering machineries. These contact sites are highly dynamic and establish an interconnected organellar network able to quickly respond to external and internal stress by changing size, abundance and molecular architecture. Here, we discuss recent work on nucleus-vacuole junctions, connecting yeast vacuoles with the nucleus. Appearing as small, single foci in mitotic cells, these contacts expand into one enlarged patch upon nutrient exhaustion and entry into quiescence or can be shaped into multiple large foci essential to sustain viability upon proteostatic stress at the nuclear envelope. We highlight the remarkable plasticity and rapid remodelling of these contact sites upon metabolic or proteostatic stress and their emerging importance for cellular fitness.

scholarly journals Synaptotagmins at the endoplasmic reticulum–plasma membrane contact sites maintain diacylglycerol homeostasis during abiotic stress

2021 ◽  
Author(s):  
Noemi Ruiz-Lopez ◽  
Jessica Pérez-Sancho ◽  
Alicia Esteban del Valle ◽  
Richard P Haslam ◽  
Steffen Vanneste ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Abiotic Stress ◽  
Fluorescent Protein ◽  
Mechanical Damage ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact ◽  
Green Fluorescent

Abstract Endoplasmic reticulum-plasma membrane contact sites (ER-PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis thaliana mutants lacking the ER-PM protein tether synaptotagmin1 (SYT1) exhibit decreased plasma membrane (PM) integrity under multiple abiotic stresses such as freezing, high salt, osmotic stress and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER-PM tether that also functions in maintaining PM integrity. The ER-PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to wild type while the levels of most glycerolipid species remain unchanged. Additionally, the SYT1-green fluorescent protein (GFP) fusion preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work uncovers a SYT-dependent mechanism of stress adaptation counteracting the detrimental accumulation of diacylglycerol at the PM produced during episodes of abiotic stress.

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