PubMed · 2458311
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
E Herman, E Elfont, T Boenisch. 1988. Prostate-specific antigen.. https://doi.org/10.1111/j.1365-2559.1988.tb01997.x
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Normal human breast epithelial (HBE) cells grown at logarithmic phase and those at the plateau phase were starved of EGF for 3 days then stimulated with EGF. HBE cells which were growth arrested at low density responded to EGF to initiate DNA synthesis 20 h later, whereas cells growth arrested at saturated density lost their responsiveness to EGF. Although the responsiveness to EGF between the two cultures at different densities was distinct, neither the number nor the affinity of EGF receptor (EGFR) in the two cultures significantly differed. In addition, the EGFR mRNA level was not affected by an increase in the cell density. A significant difference between the two cultures was the responsiveness of EGFR to EGF. The intrinsic tyrosine kinase activity and dimerization of the EGFR in cells at low density were induced by EGF, whereas those in cells at saturated density were not. Immunostaining revealed that the EGFR was localized only in the boundary region where adjacent cells are in close contact at low density but in the entire surrounding region of each cell at saturated density. The distribution of EGFR overlapped the region where the cell-cell adhesion protein, E-cadherin, is distributed. The E-cadherin mRNA levels in the two cultures were comparable; however, nearly fivefold more E-cadherin protein accumulated in cells at saturated than at low density. Incubation of cells at saturated density with an antibody to E-cadherin followed by adding EGF resulted in the stimulation of DNA synthesis, which was preceded by autophosphorylation but not dimerization of the EGFR. The results suggested that density-dependent inhibition of growth is achieved through prevention of the EGFR activation by extensive cell-cell adhesion that is mediated by excess E-cadherin.
The subcellular localization of protein kinase C (PKC)-delta was determined in HL60 cells differentiated toward monocytes/macrophages by treatment with TPA. PKC-delta was detected in the nucleus and cytoplasm of differentiated HL60 cells and, more specifically, associated with structures resembling intermediate filaments. Indirect immunostaining revealed that PKC-delta colocalized with vimentin in the cytosol and perinuclear region of these cells. Immunoprecipitation studies showed that PKC-delta was in an active (autophosphorylated) state in differentiated HL60 cells and that vimentin immunoprecipitated from these cells was also phosphorylated. Treatment of HL60 cells with the PKC-specific inhibitor chelerythrine decreased the phosphorylation of vimentin. These data suggest that vimentin is a substrate for PKC-delta and that this PKC isoenzyme may play a specific role in the regulation of shape change and cell adhesion during HL60 differentiation.
The human endothelial membrane antigens HECMA 112 and VE-cadherin were immunochemically compared. The antibodies 1.3.1 against HECMA 112 and 7B4 against VE-cadherin recognized the same protein in extracts of tissue as well as of cells. The antigen HECMA 112 was immunoprecipitated by anti-VE-Cadherin antibody 7B4.