摘要:

AbstractWe have investigated the effect of 8‐Br‐cyclic adenosine 3′:5′ monophosphate (cAMP), a pharmacological activator of cAMP‐dependent protein kinase, on the proliferation and the nuclear proto‐oncogene induction in a murine granulocyte macrophage colony‐stimulating factor (GM‐CSF)‐dependent myeloid cell line. Cells were growth arrested by granulocyte macrophage colony‐stimulating factor and serum deprivation and were allowed to proceed in the cell cycle by addition of the lymphokine in the presence or absence of 8‐Br‐cAMP.3H‐thymidine incorporation assays showed that addition of 8‐Br‐cAMP inhibited the entry of cells into S phase and the subsequent proliferation. Northern analysis showed that 8‐Br‐cAMP had opposite effects on c‐fosand c‐mycmRNA induction. 8‐Br‐cAMP induced c‐fosin the absence of any GM‐CSF. In the presence of GM‐CSF, c‐fosmRNA was superinduced (30‐fold induction compared to four‐ to fivefold by each signal alone). On the contrary, 8‐Br‐cAMP was not able to induce c‐mycin the absence of growth factor and hardly interfered with the induction of c‐mycby GM‐CSF. Phorbol myristate acetate (PMA), a pharmacological activator of the lipid and CA++‐dependent protein kinase C, was shown to induce nuclear proto‐oncogene mRNA in the GM‐CSF‐dependent cell line. We investigated the effect of 8‐Br‐cAMP on PMA‐induced c‐fosand c‐mycmRNA levels. When both cAMP dependent and lipid‐dependent kinase systems were co‐stimulated in the absence of GM‐CSF, c‐fosmessage was again superinduced (60‐fold induction). On the contrary, c‐mycmessage induction by PMA was inhibited by 80% by coactivation of cAMP‐dependent protein kinase with 8‐Br‐cAMP. Our data indicate that an antiproliferative signal induces or even superinduces c‐fosmessage and hardly interferes with c‐mycinduction, suggesting that the intracellular pathways resulting in c‐fosand c‐mycinduction may be distinct a

ISSN:0730-2312    

DOI:10.1002/jcb.240380302

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

年代:1988

数据来源: WILEY

摘要:

AbstractTwo clones of monoclonal antibodies against swine alkaline phosphatase (ALPase; orthophosphoric monoester phosphohydrolase, alkaline optimum, EC 3.1.3.1), which were useful in distinguishing human kidney and bone ALPases from liver ALPase, were successfully raised in mice. On the other hand, polyclonal antibody cross‐reacted not only with human kidney ALPase but also with all other human universal type ALPases. The difference in cross‐reactivitiy of monoclonal and polyclonal antibodies may be caused by the specific antigenicity of human enzymes. The monoclonal antibodies were able to recognize minor heterogeneity that could not be distinguished by their enzymatic properties. The present monoclonal antibody preparations will be utilized for clinical as well as basic investigations to detect minor heterogeneity among universal‐type AL

ISSN:0730-2312    

DOI:10.1002/jcb.240380303

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

年代:1988

数据来源: WILEY

摘要:

AbstractLX‐1 human lung carcinoma cells interact with human fibroblasts in culture to cause an increase in hyaluronate production (Knudson et al:Proceedings of the National Academy of Sciences of the United States of America81:6767, 1984). It is shown here that a similar increase in hyaluronate production also occurs when membranes derived from LX‐1 cells, or detergent extracts thereof, are added to cultures of the human fibroblasts. However, no stimulation occurs when membranes or extracts from fibroblasts are added to cultures of the LX‐1 cells. The hyaluronate stimulatory factor present in the detergent extracts is a heat‐ and trypsin‐sensitive protein, requires more than 12 h for its action on fibroblasts, causes an elevation in hyaluronate synthetase activity in membranes derived from the fibroblasts, and can be reconstituted into artificial lipid vesicles. Thus, it is concluded that the stimulatory factor is a membrane‐bound protein present on the surface of the LX‐1 cells and that it interacts with fibroblasts to induce increased hyaluron

ISSN:0730-2312    

DOI:10.1002/jcb.240380304

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe macrophage colony‐stimulating factor, CSF‐1 (M‐CSF), is a homodimeric glycoprotein required for the lineage‐specific growth of cells of the mononuclear phagocyte series. Apart from its role in stimulating the proliferation of bone marrow‐derived precursors of monocytes and macrophages, CSF‐1 acts as a survival factor and primes mature macrophages to carry out differentiated functions. Each of the actions of CSF‐1 are mediated through its binding to a single class of high‐affinity receptors expressed on monocytes, macrophages, and their committed progenitors. The CSF‐1 receptor (CSF‐1R) is encoded by the c‐fmsproto‐oncogene, and is one of a family of growth factor receptors that exhibits an intrinsic tyrosine‐specific protein kinase activity. Transduction of c‐fmssequences as a viral oncogene (v‐fms) in the McDonough (SM) and HZ‐5 strains of feline sarcoma virus has resulted in alterations in receptor coding sequences that affect its activity as a tyrosine kinase and provide persistent signals for cell growth in the absence of its ligand. The genetic alterations in the c‐fmsgene that unmask its latent transforming potential abrogate its lineage‐specific activity and enable v‐fmsto transform a variety of cells that do

ISSN:0730-2312    

DOI:10.1002/jcb.240380305

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

年代:1988

数据来源: WILEY

摘要:

AbstractExpression of cyclin, a non‐histone nuclear protein, during recombinant interleukin 2 (rIL2)‐driven cell‐cycle progression of cloned T lymphocytes has been assessed. We found that expression of cyclin protein, as detected by immunofluorescence, is tightly associated with proliferation, and not merely S‐phase, of L2 cells stimulated with rIL2. Cyclin immunofluorescence was detected in all cell‐cycle phases (G1/S/G2/M, as detected by flow cytometry) of proliferating L2 cells. Accumulation of cyclin mRNA levels was induced as early as 1 h after stimulation, was maximal at 25–49 h, and remained elevated throughout stimulation, as detected by Northern blot analysis. A cDNA‐encoding murine cyclin was cloned from a cDNA library prepared from IL2‐stimulated cloned T cells. The sequence of the 5′ end of the murine cyclin cDNA was determined and found to be 88% and 82% similar to the sequences of cDNA clones encoding rat and human cyclin, respectively. The present studies demonstrate that cyclin protein and mRNA accumulation are highly regulated during IL2‐induced proliferation of a cloned T cell. These data provide a framework for addressing the molecular mechanisms regulating cyclin gene expression during cel

ISSN:0730-2312    

DOI:10.1002/jcb.240380306

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

年代:1988

数据来源: WILEY

摘要:

AbstractMammary‐derived growth inhibitor (MDGI), a polypeptide growth inhibitor isolated from lactating bovine mammary tissue, previously shown to have extensive sequence homology with fatty acid‐binding proteins, was demonstrated to meet the criteria of a fatty acid‐binding protein. The protein was found to bind [3H]palmitic acid in a saturable manner and to be complexed with endogeneous free fatty acids. [3H]palmitic acid, when bound to the protein, was more rapidly taken up by the target cells (human mammary carcinoma cells [MaTu]) than was free [3H]palmitic acid, suggesting a lipid carrier function for the inhibitor. It is suggested that the fatty acid‐binding properties of MDGI may relate to its ability to inhibit cell growth in vitro and to regulate other cellular fu

ISSN:0730-2312    

DOI:10.1002/jcb.240380307

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe potential mechanisms of interferon (IFN)‐gamma and tumor necrosis factor (TNF)‐alpha action on tumor cells have been investigated in a model of mouse fibroblasts transformed by distinct retroviral vectors carrying the v‐mos, c‐myc, and v‐Ha‐ras oncogene, respectively. Treatment with both cytokines not only caused growth inhibition of v‐mos‐ and c‐myc‐transformants, but also a reversion of transformation‐induced suppression of major histocompatibility complex (MHC) class I antigen expression in all transformed cell lines. The phenotypical reversion of transformants was preceded by a selective modulation of LTR‐controlled oncogene expression. TNF‐alpha primarily affected stability of oncogene‐specific RNAs without influencing the activity of retroviral promoters. In contrast, IFN‐gamma was effective at the transcriptional level, apparently due to inhibition of LTR activity as revealed from reduced CAT activity in IFN‐gamma‐treated LTR‐CAT transformants. This IFN‐gamma‐mediated down‐regulation of retroviral promoter activity seemed to be selective for Moloney‐virus‐derived promoters, since the activity of other viral and cellu

ISSN:0730-2312    

DOI:10.1002/jcb.240380308

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe retinoblastoma susceptibility (RB) gene is unique among other cloned cancer genes because its causal role in a human cancer, retinoblastoma, was established by classical genetic methods before its isolation. Earlier hypotheses and experimental data suggested that inactivation of a gene in chromosome band 13q14 resulted in retinoblastoma formation. A gene in this region was identified as the RB gene on the basis of mutations found specifically in retinoblastoma tumors; however, its proposed biological activity in suppressing neoplasia has yet to be demonstrated. The RB gene product was identified as a nuclear phosphoprotein of 110 kD associated with DNA binding activity, suggesting that the RB protein may regulate other genes. Probes for the RB gene and gene product will be useful for genetic diagnosis of retinoblastoma susceptibility in affected families; for direct detection of mutant RB alleles; and, potentially, for genetic diagnosis of susceptibility to osteosarcoma and other tumors tentatively linked to RB‐gene dysfunction. Continued study of the RB gene should yield further insight into mechanisms of oncogenesis, development, and gene regulatio

ISSN:0730-2312    

DOI:10.1002/jcb.240380309

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

年代:1988

数据来源: WILEY

ISSN:0730-2312    

DOI:10.1002/jcb.240380301

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

年代:1988

数据来源: WILEY