scholarly journals Transforming growth factor-beta-induced growth inhibition and cellular hypertrophy in cultured vascular smooth muscle cells.

1988 ◽  
Vol 107 (2) ◽  
pp. 771-780 ◽  
Author(s):  
G K Owens ◽  
A A Geisterfer ◽  
Y W Yang ◽  
A Komoriya

We have explored the hypothesis that hypertrophy of vascular smooth muscle cells may be regulated, in part, by growth inhibitory factors that alter the pattern of the growth response to serum mitogens by characterizing the effects of the potent growth inhibitor, transforming growth factor-beta (TGF-beta), on both hyperplastic and hypertrophic growth of cultured rat aortic smooth muscle cells. TGF-beta inhibited serum-induced proliferation of rat aortic smooth muscle cells (ED50 = 2 pM); this is consistent with previously reported observations in bovine aortic smooth muscle cells (Assoian et al. 1982. J. Biol. Chem. 258:7155-7160). Growth inhibition was due in part to a greater than twofold increase in the cell cycle transit time in cells that continued to proliferate in the presence of TGF-beta. TGF-beta concurrently induced cellular hypertrophy as assessed by flow cytometric analysis of cellular protein content (47% increase) and forward angle light scatter (32-50% increase), an index of cell size. In addition to being time and concentration dependent, this hypertrophy was reversible. Simultaneous flow cytometric evaluation of forward angle light scatter and cellular DNA content demonstrated that TGF-beta-induced hypertrophy was not dependent on withdrawal of cells from the cell cycle nor was it dependent on growth arrest of cells at a particular point in the cell cycle in that both cycling cells in the G2 phase of the cell cycle and those in G1 were hypertrophied with respect to the corresponding cells in vehicle-treated controls. Chronic treatment with TGF-beta (100 pM, 9 d) was associated with accumulation of cells in the G2 phase of the cell cycle in the virtual absence of cells in S phase, whereas subsequent removal of TGF-beta from these cultures was associated with the appearance of a significant fraction of cycling cells with greater than 4c DNA content, consistent with development of tetraploidy. Results of these studies support a role for TGF-beta in the control of smooth muscle cell growth and suggest that at least one mechanism whereby hypertrophy and hyperploidy may occur in this, as well as other cell types, is by alterations in the response to serum mitogens by potent growth inhibitors such as TGF-beta.

1993 ◽  
Vol 106 (4) ◽  
pp. 1301-1311 ◽  
Author(s):  
H.F. McMurray ◽  
D. Proudfoot ◽  
J.B. Davis ◽  
D.P. Parrott ◽  
D.E. Bowyer

Murine peritoneal macrophages and the macrophage-like cell line, P388D1, were found to release both mitogenic and inhibitory modulators of growth of cells in culture. These growth factors were effective against both murine Swiss 3T3 fibroblasts and porcine aortic smooth muscle cells as assessed by [3H]thymidine incorporation into DNA and by measurement of cell number. Partial characterisation of the inhibitory activity demonstrated it to be lost on dialysis using a membrane with a 10 kDa cut-off, trypsin sensitive, heat stable, and slightly sensitive to freeze-thawing. The inhibitory activity not only affected cell growth but was found to change the morphology of porcine aortic smooth muscle cells. Gel permeation studies showed an estimated molecular mass in the range 2.5 to 6.5 kDa. The inhibitory activity could be partially purified using ion-exchange chromatography. Experiments with a neutralising antibody against transforming growth factor beta (TGF-beta) showed that TGF-beta is not responsible for the activity observed. Indomethacin had no effect on the production of inhibitor suggesting that it is not an inhibitory prostanoid. The inhibitory activity was not due to a non-specific toxic mechanism as confirmed by a [3H]adenine release assay. Incubation of P388D1 cells with cycloheximide prevented the release of inhibitory activity.


1986 ◽  
Vol 102 (4) ◽  
pp. 1217-1223 ◽  
Author(s):  
R K Assoian ◽  
M B Sporn

A specific radioimmunoassay for type beta transforming growth factor (TGF-beta) was developed and used to show that human platelets treated with thrombin release TGF-beta as a consequence of degranulation. The thrombin concentrations required to induce release of TGF-beta parallel those concentrations that release the alpha-granule marker, beta-thromboglobulin. Related studies showed that TGF-beta acts on early passage, explant cultures of bovine aortic smooth muscle cells by inhibiting the effect of mitogens on proliferation of subconfluent cell monolayers yet synergizing with mitogens to stimulate growth of the same cells when cultured in soft agar. The results show that primary cultures of bovine aortic smooth muscle cells and established normal rat kidney cells behave similarly with regard to TGF-beta action. Moreover, the data suggest that platelet-mediated proliferation of aortic smooth muscle cells in vivo may not result solely from the stimulatory effect of platelet-derived growth factor (PDGF), but rather from an interaction of platelet factors which has the intrinsic ability to limit as well as stimulate mitosis.


1993 ◽  
Vol 71 (3-4) ◽  
pp. 156-161 ◽  
Author(s):  
Yutaka Oiso ◽  
Jun Kotoyori ◽  
Takashi Murase ◽  
Yoshiaki Ito ◽  
Osamu Kozawa

Pituitary adenylate cyclase activating polypeptide (PACAP) inhibited dose dependently the DNA synthesis stimulated by arginine vasopressin (AVP) in cultured rat aortic smooth muscle cells (SMC). The inhibition was cell cycle dependent and the maximum inhibition was observed when added at the late G1 phase of the cell cycle. Vasoactive intestinal polypeptide (VIP), which shows a considerable homology with PACAP, also inhibited dose dependently the AVP-induced DNA synthesis in a cell cycle dependent manner. The maximum inhibition was also observed at the late G1 phase. The patterns of both the dose-dependent inhibitions were similar, and the inhibition by a combination of PACAP and VIP was not additive. PACAP stimulated dose dependently cAMP accumulation in aortic SMC. VIP also stimulated cAMP accumulation, and the accumulation by a combination of PACAP and VIP was not additive. Both PACAP and VIP had little effect on phosphoinositide hydrolysis in these cells. The suppression of the AVP-induced DNA synthesis by PACAP or VIP was enhanced by 3-isobutyl-1-methylxanthine, an inhibitor for phosphodiesterases. Dibutyryl cAMP, but not 8-bromo-cGMP, inhibited the AVP-induced DNA synthesis, and a combination of PACAP and dibutyryl cAMP was not additive. [Ac-Tyr1, D-Phe2]growth hormone-releasing factor, an antagonist for VIP receptor, reversed the inhibitory effect of PACAP on the AVP-induced DNA synthesis. These results suggest that PACAP has an antiproliferative effect on aortic SMC at the late G1 phase of the cell cycle through cAMP production, and that PACAP and VIP inhibit the AVP-induced DNA synthesis by a common mechanism.Key words: pituitary adenylate cyclase activating polypeptide, vasoactive intestinal polypeptide, arginine vasopressin, DNA synthesis, aortic smooth muscle cells.


1993 ◽  
Vol 120 (4) ◽  
pp. 995-1002 ◽  
Author(s):  
R Flaumenhaft ◽  
M Abe ◽  
Y Sato ◽  
K Miyazono ◽  
J Harpel ◽  
...  

Transforming growth factor beta (TGF-beta) is released from cells in a latent form consisting of the mature growth factor associated with an aminoterminal propeptide and latent TGF-beta binding protein (LTBP). The endogenous activation of latent TGF-beta has been described in co-cultures of endothelial and smooth muscle cells. However, the mechanism of this activation remains unknown. Antibodies to native platelet LTBP and to a peptide fragment of LTBP inhibit in a dose-dependent manner the activation of latent TGF-beta normally observed when endothelial cells are cocultured with smooth muscle cells. Inhibition of latent TGF-beta activation was also observed when cells were co-cultured in the presence of an excess of free LTBP. These data represent the first demonstration of a function for the LTBP in the extracellular regulation of TGF-beta activity and indicate that LTBP participates in the activation of latent TGF-beta, perhaps by concentrating the latent growth factor on the cell surface where activation occurs.


1989 ◽  
Vol 109 (1) ◽  
pp. 309-315 ◽  
Author(s):  
Y Sato ◽  
D B Rifkin

When a confluent monolayer of bovine aortic endothelial (BAE) cells is wounded with a razor blade, endothelial cells (ECs) spontaneously move into the denuded area. If bovine pericytes or smooth muscle cells (SMCs) are plated into the denuded area at low density, they block the movement of the ECs. This effect is dependent upon the number of cells plated into the wound area and contact between ECs and the plated cells. Antibodies to transforming growth factor-beta 1 (TGF-beta 1) abrogate the inhibition of BAE cell movement by pericytes or SMCs. TGF-beta 1, if added to wounded BAE cell monolayers, also inhibits cell movement. When cultured separately, BAE cells, pericytes, and SMCs each produce an inactive TGF-beta 1-like molecule which is activated in BAE cell-pericyte or BAE cell-SMC co-cultures. The activation appears to be mediated by plasmin as the inhibitory effect on cell movement in co-cultures of BAE cells and pericytes is blocked by the inclusion of inhibitors of plasmin in the culture medium.


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