Expression of recombinant platelet-derived growth factor A- and B-chain homodimers in rat-1 cells and human fibroblasts reveals differences in protein processing and autocrine effects

1988 ◽  
Vol 8 (7) ◽  
pp. 2753-2762
Author(s):  
M Bywater ◽  
F Rorsman ◽  
E Bongcam-Rudloff ◽  
G Mark ◽  
A Hammacher ◽  
...  
Keyword(s):  
Growth Factor ◽  
Human Fibroblasts ◽  
Soft Agar ◽  
Biological Properties ◽  
Platelet Derived Growth Factor ◽  
Cdna Clones ◽  
Metabolic Labeling ◽  
High Saturation ◽  
Dimeric Protein ◽  
A Chain

The autocrine effects of platelet-derived growth factor (PDGF) A- and B-chain homodimers (PDGF-AA and PDGF-BB) on rat-1 cells and human fibroblasts have been investigated by using human PDGF A- and B-chain cDNA clones expressed in a retroviral vector. Infection with replication-defective virus carrying the B-chain cDNA resulted in a phenotypical transformation resembling that induced by simian sarcoma virus. The resulting cells were focus forming in monolayer cultures, grew to high saturation densities, and formed large colonies in soft agar. The PDGF A-chain transfectants showed no transformed morphology and lacked focus-forming activity but grew to high saturation density in monolayer culture and formed small colonies in soft agar. A similar but weaker effect was obtained with an A-chain cDNA variant containing a 69-base-pair insertion in the 3' end of the protein-coding domain. A- and B-chain transfectants released PDGF receptor-competing activity into the medium, but only the medium conditioned by the B-chain transfectants possessed potent mitogenic activity on human fibroblasts. Both types of transfectants had downregulated levels of PDGF receptors; however, the B-chain transfectants were downregulated to significantly lower levels. Metabolic labeling and immunoprecipitations with PDGF antiserum showed that the PDGF B-chain protein was processed to a 24-kilodalton cell-associated and a 30-kilodalton secreted dimeric protein. The A-chain protein was rapidly secreted as a 31-kilodalton dimeric protein. The present study shows a marked difference in the autocrine effects of PDGF-AA and -BB expressed under the control of a retroviral promoter and suggests that different biological properties may be assigned to these two PDGF isoforms.

scholarly journals Expression of recombinant platelet-derived growth factor A- and B-chain homodimers in rat-1 cells and human fibroblasts reveals differences in protein processing and autocrine effects.

1988 ◽  
Vol 8 (7) ◽  
pp. 2753-2762 ◽  
Author(s):  
M Bywater ◽  
F Rorsman ◽  
E Bongcam-Rudloff ◽  
G Mark ◽  
A Hammacher ◽  
...  
Keyword(s):  
Growth Factor ◽  
Human Fibroblasts ◽  
Soft Agar ◽  
Biological Properties ◽  
Platelet Derived Growth Factor ◽  
Cdna Clones ◽  
Metabolic Labeling ◽  
High Saturation ◽  
Dimeric Protein ◽  
A Chain

The autocrine effects of platelet-derived growth factor (PDGF) A- and B-chain homodimers (PDGF-AA and PDGF-BB) on rat-1 cells and human fibroblasts have been investigated by using human PDGF A- and B-chain cDNA clones expressed in a retroviral vector. Infection with replication-defective virus carrying the B-chain cDNA resulted in a phenotypical transformation resembling that induced by simian sarcoma virus. The resulting cells were focus forming in monolayer cultures, grew to high saturation densities, and formed large colonies in soft agar. The PDGF A-chain transfectants showed no transformed morphology and lacked focus-forming activity but grew to high saturation density in monolayer culture and formed small colonies in soft agar. A similar but weaker effect was obtained with an A-chain cDNA variant containing a 69-base-pair insertion in the 3' end of the protein-coding domain. A- and B-chain transfectants released PDGF receptor-competing activity into the medium, but only the medium conditioned by the B-chain transfectants possessed potent mitogenic activity on human fibroblasts. Both types of transfectants had downregulated levels of PDGF receptors; however, the B-chain transfectants were downregulated to significantly lower levels. Metabolic labeling and immunoprecipitations with PDGF antiserum showed that the PDGF B-chain protein was processed to a 24-kilodalton cell-associated and a 30-kilodalton secreted dimeric protein. The A-chain protein was rapidly secreted as a 31-kilodalton dimeric protein. The present study shows a marked difference in the autocrine effects of PDGF-AA and -BB expressed under the control of a retroviral promoter and suggests that different biological properties may be assigned to these two PDGF isoforms.

scholarly journals Reversion of autocrine transformation by a dominant negative platelet-derived growth factor mutant.

1993 ◽  
Vol 13 (7) ◽  
pp. 4066-4076 ◽  
Author(s):  
F S Vassbotn ◽  
M Andersson ◽  
B Westermark ◽  
C H Heldin ◽  
A Ostman
Keyword(s):  
Growth Factor ◽  
Receptor Binding ◽  
Soft Agar ◽  
Cell Number ◽  
Dominant Negative ◽  
Platelet Derived Growth Factor ◽  
Wild Type ◽  
3T3 Cells ◽  
Specific Expression ◽  
A Chain

A non-receptor-binding mutant of the platelet-derived growth factor (PDGF) A chain, PDGF-0, was generated by exchanging 7 amino acids in the sequence. The mutant chains formed dimers that were similar to wild-type PDGF-AA with regard to stability and rate of processing to the mature 30-kDa secreted forms. Moreover, the mutant chains formed disulfide-bonded heterodimers with the PDGF B chain in NIH 3T3 cells heterodimer underwent the same processing and secretion as PDGF-AB. Transfection of c-sis-expressing 3T3 cells with PDGF-0 significantly inhibited the transformed phenotype of these cells, as determined by the following criteria. (i) Compared with PDGF-0-negative clones, PDGF-0-producing clones showed a reverted morphology. (ii) Clones producing PDGF-0 grew more slowly than PDGF-0-negative clones, with a fivefold difference in cell number after 14 days in culture. (iii) The expression of PDGF-0 completely inhibited the ability of the c-sis-expressing 3T3 cells to form colonies in soft agar; this inhibition was overcome by the addition of recombinant PDGF-BB to the culture medium, showing that the lack of colony formation of these cells was not due to a general unresponsiveness to PDGF. The specific expression of a PDGF-0/PDGF wild-type heterodimer in COS cells revealed that the affinity of the mutant heterodimer for the PDGF alpha receptor was decreased by approximately 50-fold compared with that of PDGF-AA. Thus, we show that a non-receptor-binding PDGF A-chain mutant neutralizes in a trans-dominant manner the autocrine transforming potential of the c-sis/PDGF B chain by forming low-affinity heterodimers with wild-type PDGF chains. This method of specifically antagonizing the effect of PDGF may be useful in investigations of the role of PDGF in normal and pathological conditions.

Reversion of autocrine transformation by a dominant negative platelet-derived growth factor mutant

1993 ◽  
Vol 13 (7) ◽  
pp. 4066-4076
Author(s):  
F S Vassbotn ◽  
M Andersson ◽  
B Westermark ◽  
C H Heldin ◽  
A Ostman
Keyword(s):  
Growth Factor ◽  
Receptor Binding ◽  
Soft Agar ◽  
Cell Number ◽  
Dominant Negative ◽  
Platelet Derived Growth Factor ◽  
Wild Type ◽  
3T3 Cells ◽  
Specific Expression ◽  
A Chain

A non-receptor-binding mutant of the platelet-derived growth factor (PDGF) A chain, PDGF-0, was generated by exchanging 7 amino acids in the sequence. The mutant chains formed dimers that were similar to wild-type PDGF-AA with regard to stability and rate of processing to the mature 30-kDa secreted forms. Moreover, the mutant chains formed disulfide-bonded heterodimers with the PDGF B chain in NIH 3T3 cells heterodimer underwent the same processing and secretion as PDGF-AB. Transfection of c-sis-expressing 3T3 cells with PDGF-0 significantly inhibited the transformed phenotype of these cells, as determined by the following criteria. (i) Compared with PDGF-0-negative clones, PDGF-0-producing clones showed a reverted morphology. (ii) Clones producing PDGF-0 grew more slowly than PDGF-0-negative clones, with a fivefold difference in cell number after 14 days in culture. (iii) The expression of PDGF-0 completely inhibited the ability of the c-sis-expressing 3T3 cells to form colonies in soft agar; this inhibition was overcome by the addition of recombinant PDGF-BB to the culture medium, showing that the lack of colony formation of these cells was not due to a general unresponsiveness to PDGF. The specific expression of a PDGF-0/PDGF wild-type heterodimer in COS cells revealed that the affinity of the mutant heterodimer for the PDGF alpha receptor was decreased by approximately 50-fold compared with that of PDGF-AA. Thus, we show that a non-receptor-binding PDGF A-chain mutant neutralizes in a trans-dominant manner the autocrine transforming potential of the c-sis/PDGF B chain by forming low-affinity heterodimers with wild-type PDGF chains. This method of specifically antagonizing the effect of PDGF may be useful in investigations of the role of PDGF in normal and pathological conditions.

Isolation and sequencing of a cDNA clone homologous to the v-sis oncogene from human endothelial cells

1986 ◽  
Vol 6 (8) ◽  
pp. 3018-3022
Author(s):  
B D Tong ◽  
S E Levine ◽  
M Jaye ◽  
G Ricca ◽  
W Drohan ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Growth Factor ◽  
Cdna Library ◽  
Cdna Clone ◽  
Umbilical Vein ◽  
Platelet Derived Growth Factor ◽  
Human Endothelial Cells ◽  
A Chain ◽  
Umbilical Vein Endothelial Cells ◽  
Reading Frames

A clone containing the 3' end of the mRNA for the human c-sis gene (homologous to the B chain of platelet-derived growth factor) was isolated from a cDNA library derived from human umbilical vein endothelial cells and then sequenced. The analysis of possible translation products in all three reading frames indicated that the A chain of platelet-derived growth factor was not coded for within the 3' end of the c-sis mRNA. The 3' end of the mRNA for c-sis is contained in or adjacent to exon 6.

Platelet-derived growth factor and growth-related genes in rat lung. II. Effect of exposure to 85% O2

1992 ◽  
Vol 262 (2) ◽  
pp. L140-L146 ◽  
Author(s):  
R. N. Han ◽  
S. Buch ◽  
B. A. Freeman ◽  
M. Post ◽  
A. K. Tanswell
Keyword(s):  
Gene Expression ◽  
Cell Division ◽  
Growth Factor ◽  
Receptor Gene ◽  
Platelet Derived Growth Factor ◽  
Chain Gene ◽  
Transcription Analysis ◽  
A Chain ◽  
Type Receptor ◽  
Receptor Gene Expression

The expression of platelet-derived growth factor (PDGF), its receptor, and related genes was studied in the lung tissue of rats exposed to air or 85% O2. PDGF-B chain mRNA was increased by 6 days and PDGF B-type receptor mRNA was increased by 4 and 6 days of exposure to 85% O2. Despite a continued increase of cell division, both PDGF-B chain and B-type receptor mRNAs had returned to control values by 14 days of exposure to 85% O2. PDGF-A chain mRNA was unaffected by exposure to 85% O2. Nuclear runoff transcription analysis confirmed increased transcription of PDGF-B chain mRNA, whereas Western blot analysis of lung homogenates suggested consequent increased translation of PDGF-B chain mRNA to PDGF-BB at 7 days of exposure to 85% O2. Combined immunocytochemistry and autoradiography localized PDGF-BB to the major site of cell division, the pulmonary interstitium. We speculate that the early pulmonary fibroblast hyperplasia observed following exposure to 85% O2 is mediated by increased PDGF-B chain gene expression and may also be mediated by changes in PDGF B-type receptor gene expression.

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