Respective roles of protein tyrosine kinases and protein kinases C in the upregulation of β‐catenin distribution, and compaction in mouse preimplantation embryos: a pharmacological approach

Abstract

The cellular distribution of beta-catenin was determined by western blotting and laser confocal scanning microscopy in both control and pharmacologically-manipulated mouse preimplantation embryos. Most of the stored maternal beta-catenin is Triton X-100-extractable and distributed throughout the cytoplasm. In 2-cell stage embryos, the remaining molecules are concentrated in regions of cell contact and, to a lesser extent, at non apposed surfaces. Association of beta-catenin with the cortex of non apposed membranes decreases as cleavage proceeds, and is lost at compaction. In contrast to the rapid cross-linking of cell surfaces induced by wheat germ agglutinin, the diacylglyceride-induced compaction-like adhesion of 2- and 4-cell embryos correlates with complete restriction of beta-catenin to the apposing membranes. On the contrary, tyrphostin B46, a specific protein tyrosine kinase inhibitor, fails to induce both premature beta-catenin relocalisation and compaction. In addition, we show that orthovanadate induces a dramatic increase in the level of phosphotyrosine labelling of cell-cell junctions in compacted 8-cell stage embryos without inducing their decompaction. However, most of these orthovanadate tyrosine-phosphorylated proteins are detergent-soluble, while beta-catenin restricted to the apposing membranes is not. In conclusion, our results confirm that diacylglycerol-dependent kinases upregulate both beta-catenin redistribution and compaction, and indicate that neither tyrosine kinases, nor tyrosine phosphatases are critical for the proper onset of compaction which seems, in addition, not causally linked to tyrosine dephosphorylation of beta-catenin.

African Swine Fever Virus Protein p54 Interacts with the Microtubular Motor Complex through Direct Binding to Light-Chain Dynein

“…In the present study, virus yields were also greatly affected at early infection steps by sodium orthovanadate (Na 3 OV 4 ), an inhibitor drug previously reported to inhibit dynein-dependent movement (18). Na 3 OV 4 is an inhibitor of tyrosine phosphatase activity and function (21), and it has been shown to inhibit minus-end-directed movement (54). Tyrosine phosphorylation regulates the structure and function of some cytoskeletal proteins (21,60).…”

“…Na 3 OV 4 is an inhibitor of tyrosine phosphatase activity and function (21), and it has been shown to inhibit minus-end-directed movement (54). Tyrosine phosphorylation regulates the structure and function of some cytoskeletal proteins (21,60). When Na 3 OV 4 was added prior to infection, virus production was strongly inhibited and there was no intracytoplasmic staining by immunofluorescence.…”

“…Sodium orthovanadate (Na 3 VO 4 ), a tyrosine phosphatase inhibitor (21,60), was used at 100 M or 10 M in Dulbecco's modified Eagle's medium. Controls were simultaneously treated with solvents.…”

Inhibition of the Beta-Catenin Signaling Pathway in Blastocyst and Uterus During the Window of Implantation in Mice1

“…It has been shown previously that the bulk of beta-catenin accumulation occurs in the cytoplasm from 2-cell embryos to the morula stage, but no evidence of nuclear beta- catenin staining has been observed [20], indicating that the beta-catenin signaling pathway may not be activated during this period. Consistent with these earlier observations, in the present study active beta-catenin was not detected in either the cytoplasm or the nucleus from 2-to 16-cell embryos (Fig.…”

Morphogenesis of the mammalian blastocyst

“…β-catenin, which is phosphorylated on ser/thr residues at the time of compaction, is likely to be a target of this signaling cascade. (Goval et al, 2000;Pauken and Capco, 1999). The cytoskeleton protein ezrin is another good candidate (Louvet-Vallée et al, 2001).…”