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991.
The effects of the tumor promoter phorbol 12-myristate 13-acetate (PMA) on the proliferation, protein kinase C activity (PKC), and c-fos gene expression were examined in cultures of young and senescent (90-95% lifespan completed) WI-38 human diploid fibroblasts. We observed that, following stimulation with medium containing 10% fetal bovine serum (FBS), the translocation of PKC from the cytosol to the particulate compartment was less efficient in senescent WI-38 cells than in young cells. However, when PMA was added to the medium, the intracellular distribution of PKC activity in old cells became nearly identical to that observed in young cells. The inducibility of c-fos mRNA by serum addition, which is a protein kinase C-dependent event [64], was significantly amplified in the presence of PMA. Moreover, the duration of peak c-fos expression, after stimulation by FBS and PMA, increased in senescent cells as compared to young cells. Our results reveal that the normal signal transduction pathway is altered in senescent, slowly proliferating human fibroblasts and that it can be partially restored in the presence of the tumor promoter PMA. 相似文献
992.
Philip J. Rijken Rolf P. De Groot Nico Van Belzen Siegfried W. De Laat Johannes Boonstra Arie J. Verkleij 《Experimental cell research》1993,204(2)
Epidermal growth factor (EGF)-induced c-fos and c-jun expression is strongly suppressed in microgravity. We investigate here whether this is due to inhibition of processes occurring during the initiation of EGF-induced signal transduction. For this purpose, EGF-induced receptor clustering is used as a marker. The lateral distribution of EGF receptors is directly visualized at an ultrastructural level by the label-fracture method. Quantification of the receptor distributions shows that EGF-induced receptor redistribution is similar under normal and microgravity conditions. This suggests that microgravity influences EGF-induced signal transduction downstream of EGF binding and EGF receptor redistribution, but upstream of early gene expression in human A431 cells. 相似文献
993.
L. Moens J. Vanfleteren I. De Baere A.M. Jellie W. Tate C.N.A. Trotman 《FEBS letters》1993,320(3):284-287
994.
995.
J. Féthière R. Graihle L. Larose K. Babinski H. Ong A. De Léan 《Molecular and cellular biochemistry》1993,124(1):11-16
The differential distribution of natriuretic peptide receptor subtypes and their distinct properties were assessed in mammalian cellular models which were screened for their ability to produce cGMP upon stimulation by different natriuretic peptides. The ANF-R1A receptor subtype was distinguished by its selective activation by atrial natriuretic factor (ANF) while the ANF-R1C was characterized by preferential stimulation by C-type natriuretic peptide (CNP). AT-t20 pituitary cells, bovine adrenal chromaffin cells, and NIH-3T3 fibroblasts mainly express the ANF-R1C receptor subtype. Other cell lines such as PC12, RASM and GH3 express significant but varying amounts of both ANF-R1A and ANF-R1C subtypes. A10 and NIH cells which express high density of ANF-R2 receptor subtype, also demonstrate a higher sensitivity to CNP over ANF suggesting that they express significant amounts of ANF-R1C. Studies of the regulation by ATP of guanylyl cyclase activity indicate that both ANF-R1A and ANF-R1C subtypes are modulated in the same manner. In the presence of Mn2+, ATP inhibits the CNP-stimulated guanylyl cyclase activity while in the presence of Mg2+ adenine nucleotides potentiate the stimulation by CNP. In addition, we show that like the ANF-R1A, the ANF-R1C guanylyl cyclase activity can be regulated by phosphorylation since preincubation with TPA or FKL attenuates the subsequent stimulation by CNP in cultured cells. The results presented demonstrate that specific cell types express distinct natriuretic peptide receptor subtypes and also that the newly characterized ANF-R1C subtype is regulated by ATP and serine/threonine kinases in the same way as the ANF-R1A subtype.Abbreviation ANF
atrial natriuretic factor
- BNP
brain natriuretic peptide
- CNP
C-type natriuretic peptide
- ATP
adenosine-5-triphosphate
- IBMX
3-isobutyl-1-methylxanthine
- TPA
12-O-tetradecanoyl-phorbol-13-acetate
- FKL
forskolin
- PKC
calcium-phospholipid-dependent protein kinase
- PKA
cAMP-dependent protein kinase
- PKG
cGMP-dependent protein kinase
- C-ANF
[Cys116]-ANF-(102-116)-NH2
- CC
chromaffin cells 相似文献
996.
E. Ortega C. Barriga M. De la Fuente 《European journal of applied physiology and occupational physiology》1993,66(1):37-42
All the stages of the phagocytic process of blood neutrophils were compared in sedentary young women (no formal exercise during the previous 24 months) and elite sportswomen (basketball players from the Siglo XXI Spain Selection, in the middle of their competitive season) at rest. The sportswomen had performed no exercise since the day before taking the blood samples. Adherence of neutrophils to nylon fibre, which is similar to endothelium adherence, was not different between the two groups [62 (SD 14) and 58 (SD 18) in control and sport groups respectively]. Chemotaxis (studied in a Boyden chamber using a filter with 3 m pore diameter) was found to be stimulated (P<0.001) in the sportswomen [105 (SD 30)] with respect to the controls [39 (SD 9)]. Attachment, ingestion and killing by neutrophils was measured by incubation of the neutrophils with serum and a suspension ofCandida albicans. While no statistical differences were found in attachment ofC. albicans after 15 min incubation [71 (SD 8) in the control group, and 74 (SD 20) in the sport group], the sportswomen showed a higher (P<0.001) ingestion capacity forC. albicans at both 15 min [53 (SD 13) and 111 (SD 32) in control and sportswomen respectively] and 60 min [control 90 (SD 10), and sport group 224 (SD 21)] incubation. The greater phagocytic capacity in sportswomen was correlated with a higher plasma cortisol concentration (P <0.05) and a lower plasma ACTH concentration (P <0.001) in this group. It is concluded that elite women basketball players have a greater phagocytic capacity than sedentary women, possibly mediated by the higher plasma cortisol concentration in the sportswomen. 相似文献
997.
Nobuko Naito Evelyn Grace De Jesus Yasumitsu Nakai Tetsuya Hirano 《Cell and tissue research》1993,272(3):429-437
Tissue non-specific alkaline phosphatase is a membrane-bound glycoprotein enzyme which is characterized by its phosphohydrolytic, protein phosphatase, and phosphotransferase activities. This enzyme is distributed virtually in all mammalian tissues, particularly during embryonic development. Its expression is stagespecific and can be demonstrated in the developing embryo as early as the 2-cell stage. It has been suggested that tissue non-specific alkaline phosphatase might play a role in tissue formation. In the study reported here, a genetransfer approach was employed to investigate possible roles for this enzyme by inserting the cDNA for rat tissue non-specific alkaline phosphatase into CHO and LLC-PK1 cells. Permanently transfected cell-lines expressing varying levels of alkaline phosphatase were estblished. The data showed that functional enzyme was expressed in the transfected cells. Cell spreading and attachment were enhanced in transfected CHO cells expressing high levels of tissue non-specific alkaline phosphatase but not in the LLC-PK1 cells. Further, in CHO cells, proliferation was shown to be inversely proportional to the level of the tissue non-specific alkaline phosphatase expression. Homotypic cell association was demonstrated in both alkaline phosphatase-positive and alkaline phosphatase-negative cells in both CHO and LLC-PK1 celllines. Taken together, these findings suggest that in addition to a role in mineralization of bone, tissue nonspecific alkaline phosphatase might also play a role in other cell activities, including those related to differentiation, such as cell-cell or cell-substrate interaction and proliferation. 相似文献
998.
J. -P. Timmermans M. Barbiers D. W. Scheuermann W. Stach D. Adriaensen M. H. A. De Groodt-Lasseel 《Cell and tissue research》1993,272(1):49-58
The small intestine of the pig has been investigated for its topographical distribution of enteric neurons projecting to the cranial mesenteric ganglion, by using Fast Blue or Fluorogold as a retrogradely transported neuronal tracer. Contrary to the situation in small laboratory animals such as rat and guinea-pig, the intestinofugally projecting neurons in the porcine small intestine were not restricted to the myenteric plexus, but were observed in greater numbers in ganglia of the outer submucous plexus. The inner submucous plexus was devoid of labelled neurons. Retrogradely labelled neurons were mostly found, either singly or in small aggregates, in ganglia located within a narrow border on either side of the mesenteric attachment. For both nerve networks, their number increased from duodenum to ileum. All the retrogradely labelled neurons exhibited a multidendritic uniaxonal appearance. Some of them displayed type-III morphology and stained for serotonin. This study indicates that, in the pig, not only the myenteric plexus but also one submucous nerve network is involved in the afferent component of intestino-sympathico-intestinal reflex pathways. The finding that some of the morphologically defined type-III neurons participate in these reflexes is in accord with the earlier proposal that type-III neurons are supposed to fulfill an interneuronal role, whether intra- or extramurally. 相似文献
999.
1000.