摘要:

AbstractThe murine macrophage‐derived cell line P388D1secretes the lymphokine inter‐leukin 1 (IL‐1) when stimulated by a variety of agents. When stimulated by bacterial lipopolysaccharide (LPS) the cells release IL‐1 in both high and low molecular weight (m.w.) forms. The proportion of high m.w. IL‐1 is reduced when IL‐1‐containing supernatants are concentrated by ammonium sulfate precipitation subsequent to hollow‐fiber filtration. The high m.w. form can be converted to the low m.w. form by proteolysis, reduction and alkylation, or chromatography in a dissociating solvent. The low m.w. form remains as such, even when reconcentrated in fetal calf serum‐containing medium. The high m.w. form thus likely consists of a complex between low m.w. IL‐1 and another protein secreted by

ISSN:0730-2312    

DOI:10.1002/jcb.240260202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractIn order to better understand the mechanism by which changes in the fatty acid composition of cellular lipids occur in leukemia cell lines induced to differentiate, the activity of the first enzyme of fatty acid biosynthesis, acetyl‐CoA carboxylase (EC 6.4.1.2) was measured in HL‐60 promyclocytic leukemia cells before, during and after treatment with compounds that induce these cells to mature to neutro‐phillike cells. After 24 h of exposure to dimethylsulfoxide, retinoic acid, or butyric acid, no morphological or biochemical (nitroblue tetrazolium reduction) evidence of differentiation occurred, but acetyl‐CoA carboxylase activity decreased 44, 44.5, and 49% respectively, compared to untreated cells. After 7 days of culture in the presence of these agents, 79, 83, and 72% of cells acquired the ability to reduce nitroblue tetrazolium (versus 15% of control cells) and enzyme activity decreased 92.7, 99.7, and 98%, compared to control cultures, with the three compounds respectively. Thus, some of the reported changes in fatty acid composition of leukemia cells with differentiation may arise, in part, from the depression of the de novo fatty acid biosynthetic pathway and the loss of acetyl‐CoA carboxylase activity may be a useful marker for neutrophilic differentiation in HL

ISSN:0730-2312    

DOI:10.1002/jcb.240260203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractCellular oncogenes and their activated and retrovirus‐coded counterparts play an important role in cellular regulation. Here the relationship between such oncogenes and the genes coding for the transforming proteins of the papovaviruses, polyoma viruses, and simian virus 40 (SV40) is discussed. It is concluded that polyoma virus may transform established cells by a mechanism involving activation of a cellular oncogene product, whereas SV40 may transform by a mechanism involving a previously little studied cytoplasmic form of the transforming protei

ISSN:0730-2312    

DOI:10.1002/jcb.240260204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe transforming protein of Rous sarcoma virus (RSV) typically appears as a single phosphorylated polypeptide designated pp60v‐src, pp60v‐srcpossesses a protein kinase activity specific for tyrosine residues on select protein substrates. Treatment of RSV‐transformed cells with vanadium ions resulted in the appearance of an electrophoretic variant of pp60v‐srcand was paralleled by a significant increase in the src kinase specific activity in purified enzyme preparations. Both the normal (standard) src kinase and the src kinase preparations obtained from vanadium‐treated cells exhibited similar optimal activity profiles for MgCl2, KCl, and pH. Furthermore, their site specificities of phosphorylation of the substrates casein and vinculin were the same. The reaction kinetic profile of the standard src kinase showed a nonlinear pattern, while the vanadium enzyme exhibited conventional linear Michaelis‐Menten kinetics. These results are discussed with respect to the possible functional regulation of pp60v‐srcactivity by a vanadium‐sensitive protein phosp

ISSN:0730-2312    

DOI:10.1002/jcb.240260205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240260206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractOne of the major problems in developmental biology concerns how differential gene activity is regionally controlled. One approach to this problem is the use of mesenchyme specification of epithelial‐specific gene expression, such as, during tooth morphogenesis or lung morphogenesis. In the example of tooth morphogenesis, dental papilla ectomcsenchyme induces de novo gene expression as assayed by detection of amelogenin transcripts, or immunodetection of amelogenin poly‐peptidcs within ameloblast cells. This process does not require serum supplementation or exogenous factors during epithelial‐mesenchymal interactions in vitro. In contrast, lung morphogenesis requires hormones to mediate mesenchyme‐derived influences upon type II epithelial cell differentiation and the production of pulmonary surfactant (eg, neutral and phospholipids, surfactant proteins). Glucocorticoids are required to stimulate the release of fetal pneumonocyte factor (FPF) from fibroblasts which, in turn, enhance the production of pulmonary surfactant. Thy‐roxin appears to regulate the relative responsiveness of progenitor type II cells to steroid‐stimulated release of FPF. This review will highlight key concepts associated with these developing organ systems and emphasize the problem of regional controls which regulate epithelial cell‐specific

ISSN:0730-2312    

DOI:10.1002/jcb.240260207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effect of neonatal deafferentation on the expression of a neuronal cell surface heparan sulfate proteoglycan (HeS‐PG) was investigated in the developing rat superior cervical ganglion. Two monoclonal antibodies, one directed against the core protein of HeS‐PG, and one to a determinant associated with a heparan sulfate side‐chain, were used to monitor postnatal increases of HeS‐PG by ra‐dioiminunoassay. Following neonatal deafferentation by section of the cervical sympathetic trunk, total protein per ganglion was slightly reduced at survival times of 7, 14, and 30 days. Expression of the core protein determinant on HeS‐PG was not altered in deafferented ganglia. In contrast, levels of side‐chain determinant were significantly reduced at 14 and 30 days. These results suggest that processing of HeS‐PG side‐chains by principal ganglionic neurons is partially regulated by transsynaptic influences during development. Transsynaptic regulation of neuronal development may be a more general process than was believed previously, with effects not limited to molecules associated with syn

ISSN:0730-2312    

DOI:10.1002/jcb.240260208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240260201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY