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1. |
Cell Density Regulates Differential Production of bFGF Transcripts |
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Growth Factors,
Volume 9,
Issue 3,
1993,
Page 195-203
BostLaurie M.,
HjelmelandLeonard M.,
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摘要:
AbstractIn vitrocultures of human retinal pigment epithelial (RPE) cells were used to study the regulation of basic fibroblast growth factor (bFGF) gene expression. Four transcripts of 7.0, 3.7, 2.2, and 1.2kB are produced from the bFGF gene. Increasing cell density has a profound effect on the expression of the 7.0 kB transcript relative to the 3.7 kB transcript. Here, evidence is presented suggesting that posttranscriptional processing events are responsible for differential expression of the 7.0 and 3.7kB bFGF transcripts as a function of cell density. Primer extension analysis demonstrates that these two transcripts originate from a single transcription initiation site. Determination of the half-lives of the 7.0 and 3.7kB transcripts at confluent cell density did not explain the relative expression of these mRNAs. These differences may arise from the use of alternative polyadenylation sites in the 3' untranslated region (UTR) as a function of cell density. Polysomal analysis indicates no selective translation of any of the four bFGF transcripts in RPE cells.
ISSN:0897-7194
DOI:10.3109/08977199309010832
出版商:Taylor&Francis
年代:1993
数据来源: Taylor
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2. |
Multiple Transcription Start Sites in the Rat Insulin-Like Growth Factor-I Gene Give Rise to IGF-I mRNAs that Encode Different IGF-I Precursors and are Processed DifferentlyIn Vitvo |
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Growth Factors,
Volume 9,
Issue 3,
1993,
Page 205-221
SimmonsJames G.,
van WykJudson J.,
HoytEileen C.,
LundP. Kay,
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摘要:
AbstractTwo distinct class 1 and class 2 rat liver IGF-I mRNAs contain different 5' leader exons, 1 and 2. RNase protection, primer extension, RACE PCR and ribonuclease H mapping established the complete structure of the 5' end of class 1 and class 2 IGF-I mRNAs. Two major transcription start sites in exon 1 yield class 1 IGF-I mRNAs, including 345 or 245 bases of exon 1. Multiple, clustered transcription start sites in exon 2 yield class 2 IGF-I mRNAs with 84–50 bases of exon 2. Cell-free translation ofin vitrotranscribed IGF-I mRNAs suggests that class 1 and class 2 mRNAs preferentially initiate translation at distinct AUG codons to result in IGF-I precursors with either 48 residue class 1 pre-peptides or 32 residue class 2 pre-peptides. Some translation initiation also occurs at a downstream AUG common to class 1 and 2 mRNAs to yield IGF-I precursors with a 22 residue pre-peptide. Inclusion of microsomal membranes in translations suggests that the three different pre-peptides each function as co-translationally cleaved signal peptides. However, treatment of processed precursors with endoglycosidase H indicates that co-translational processing of precursors with 22 and 32 residue pre-peptides leads to glycosylation of downstream IGF-I precursor sequences whereas co-translational processing of precursors with 48 residue pre-peptide is not associated with glycosylation.
ISSN:0897-7194
DOI:10.3109/08977199309010833
出版商:Taylor&Francis
年代:1993
数据来源: Taylor
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3. |
Secretion of Epidermal Growth Factor-Like Molecular Species by Lung Parenchymal Macrophages: Induction by Interferon-γ |
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Growth Factors,
Volume 9,
Issue 3,
1993,
Page 223-230
KumarRakesh K.,
O'gradyRoslynn,
LiWei,
RajkovicIvan,
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摘要:
AbstractA population of cells enriched for pulmonary interstitial macrophages was obtained by differential adherence of lung parenchymal cells released by dissociation with trypsin. These cells secreted a molecule or molecules that bound to epidermal growth factor (EGF) receptors expressed on pulmonary fibroblasts. Secretion was reprodudbly stimulated by exposure of the macrophages to interferon-y. Binding to EGF receptors could be blocked by a polyclonal antibody to EGF. It could also be partially blocked by incubation with heparin, suggesting that at least a component of the activity might be due to a member of the heparin-binding subgroup of the EGF family of growth factors. Because pulmonary fibrosis is consistently associated with inflammatory accumulation of activated T-lymphocytes, induction by interferon-y of growth factor secretion by macrophages could have pathoge-netic importance. We speculate that similar cellular interactions may play a role in the progression of other chronic inflammatory lesions to fibrosis.
ISSN:0897-7194
DOI:10.3109/08977199309010834
出版商:Taylor&Francis
年代:1993
数据来源: Taylor
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4. |
Constitutive and Inducible Expression of PDGF in the Human Basophilic Cell Line, KU 812 |
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Growth Factors,
Volume 9,
Issue 3,
1993,
Page 231-241
ForsbergK.,
NilssonG.,
RenZ. P.,
HellmanL.,
WestermarkB.,
NistérM.,
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摘要:
AbstractThe human basophilic cell line KU 812, that also has some mast cell characteristics, was found to express the PDGF-A gene and secrete PDGF-A like activity. After treatment with IL-6+TNF-α, the PDGF-A mFNA expression increased as did cytoplasmic immunostaining with anti-PDGF antibodies. Secretion of PDGF-A was visualized by immunoprecipitation. An augmentation of non-secreted PDGF-like activity after IL-6+TNF-αtreatment was not accompanied by induction of the long splice variant of the PDGF-A-chain mRNA. Treatment with TPA caused an increase in PDGF-A expression and in addition, an induction of PDGF-B transcripts were seen. Staining of cytospin preparations with anti-PDGF antibodies visualized a substantial increase in immunostaining of the TPA treated cells and both intracellular and secreted PDGF-AA-like activity was substantially increased as compared to untreated control cultures. There was a concomitant induction of exon 6 specific mRNA, corresponding to a cellular retention signal after TPA treatment. Our results show that PDGF can be produced by a cell line of the basophilic/mast cell lineage, i.e. cells involved in allergic disorders and inflammation.
ISSN:0897-7194
DOI:10.3109/08977199309010835
出版商:Taylor&Francis
年代:1993
数据来源: Taylor
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5. |
Phosphotyrosine-Containing Proteins are Concentrated in Differentiating Cells During Chicken Embryonic Development |
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Growth Factors,
Volume 9,
Issue 3,
1993,
Page 243-252
PatstoneGail,
MaherPamela A.,
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摘要:
AbstractProtein tyrosine phosphorylation may be an important indicator of both the proliferative status and differentiation status of cells during embryonic development. To determine how each of these factors contributes to the level of phosphotyrosine-containing proteins detectable in embryonic tissues we have used immunohistochemistry with anti-phosphotyrosine antibodies on sections of developing chicken embryos. In contrast to an earlier study (Takata and Singer, 1988) we found proteins phosphorylated on tyrosine residues to be present in many dfferent cells of the developing chicken embryo. The successful detection of phosphotyrosine-containing proteins in many cell types required the presence of sodium orthovanadate, a phosphotyrosine phosphatase inhibitor, during fixation. Despite the fact that the majority of tyrosine kinases identified to date are growth factor receptors, the highest levels of phosphotyrosine-containing proteins in many tissues were localized to populations of cells which were differentiating or migrating rather than dividing.
ISSN:0897-7194
DOI:10.3109/08977199309010836
出版商:Taylor&Francis
年代:1993
数据来源: Taylor
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