The effects of lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) on T cell expression of heparin-binding epidermal growth factor-like growth factor (HB-EGF), the diphtheria toxin (DT) receptor, were investigated in the Tsup-1 cultured line of human CD4+ 8+ 3low T lymphoblastoma cells. Tsup-1 cells bear endothelial differentiation gene (edg)-2 and -4-encoded G protein-coupled receptors (GPCRs) for LPA and Edg-3 and -5 GPCRs for S1P. Suppression by DT of Tsup-1 cell protein synthesis was enhanced by LPA and S1P, with lipid structural specificity similar to that required for their recognition by Edg receptors. LPA and S1P increased the Tsup-1 cell level of immunoreactive HB-EGF, and neutralizing antibodies to HB-EGF inhibited LPA and S1P enhancement of Tsup-1 cell susceptibility to DT. Stabilized transfection of Tsup-1 cells with a combination of plasmids encoding Edg-2 plus -4 antisense mRNA suppressed the levels of Edg-2 and -4, but not Edg-3 and -5, in Western blots and reduced in parallel the increments in HB-EGF and susceptibility to DT evoked by LPA but not S1P. Similar transfection with Edg-3 plus -5 antisense plasmids suppressed Tsup-1 cell levels of immunoreactive Edg-3 and -5, but not Edg-2 or -4, and concurrently reduced S1P-, but not LPA-, induced Tsup-1 cell increases in both HB-EGF and susceptibility to DT. Edg GPCR-mediated LPA and S1P enhancement of T cell sensitivity to DT, thus, may be attributable to increased expression of the DT receptor HB-EGF.

Cell Line↗

PubMedDate not supplied

Protective effects of acetazolamide and hyperbaric oxygenation on experimentally induced syncope.

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Acetazolamide↗

PubMedDate not supplied

Study on RNA synthesis in the retina and retinal pigment epithelium of mice by light microscopic radioautography.

With the aim of determining the distribution of the incorporation of 3H-uridine in both retina and retinal pigment epithelium (RPE), the mouse eyes at embryonic day 9.5 (E 9.5), E 12.5, E 14.5, E 16.5, E 18.5 of gestational ages, and postnatal day 1 (P 1), P 3, P 7, P 14 were analyzed by light microscopic radioautography. Small pieces of the ocular tissues were labelled with 3H-uridine in vitro and light microscopic radioautographs were prepared. The average grain numbers per cell of the respective regions of tissues were calculated. In the retina, the grain numbers increased gradually from E 9.5 to P 1 and reached the maximal value at P 1, and then decreased until P 14. However, the grain numbers were more in the vitreal portion than those in the scleral portion at E 16.5 and then became more in the scleral portion from E 18.5 to P 14. It is considered that the ganglion and bipolar cells finish the RNA synthesis earlier, while the photoreceptor cells do it later during the fetal and postnatal development. In the RPE, the grain numbers gradually increased from E 12.5 to P 7 and then decreased until P 14. Considering the same ages, the grain numbers increased in the following order, anterior, equatorial and posterior regions during embryonic stages, but decreased in the same order after birth. Therefore, it is suggested that the activity of RNA synthesis in PE cells is higher in the posterior region than in the anterior region during embryonic stages. But the activity ascends generally and becomes relatively higher in the anterior region, after birth. Comparing the retina and RPE, it was noted that the grain numbers in the RPE were more important than in the retina and that the maximal value was at P 1 in the retina, while it was at P 7 in the RPE. From these results, it can be concluded that the RNA synthesis ceases earlier in the retina than in the RPE.

Aging↗