scholarly journals Biased distribution of recombination sites within S regions upon immunoglobulin class switch recombination induced by transforming growth factor beta and lipopolysaccharide.

1992 ◽  
Vol 175 (6) ◽  
pp. 1539-1546 ◽  
Author(s):  
T Iwasato ◽  
H Arakawa ◽  
A Shimizu ◽  
T Honjo ◽  
H Yamagishi

We have characterized extrachromosomal circular DNAs from adult mouse spleen cells that were induced to switch to immunoglobulin A (IgA) with bacterial lipopolysaccharide (LPS) and transforming growth factor beta (TGF-beta), and identified breakpoints of S mu/S gamma 3, S mu/S gamma 2, S mu/S alpha, S gamma 3/S alpha, and S gamma 2/S alpha recombinants. The S mu recombination donor sites clustered in the 3' half of the S mu region, while the S alpha recombination acceptor sites clustered in the 5' half of the S alpha region. In addition, donor and acceptor sites of S gamma regions also clustered in the 3' and 5' parts, respectively. These site preferences are in sharp contrast to the dispersed distribution of S mu/S gamma 1 breakpoints within both S mu and S gamma 1 regions upon IgG1 switch induced by LPS and interleukin 4. Our results support the hypotheses that TGF-beta increases the frequency of switch recombination events to IgA and that the switch recombination to IgA often proceeds by successive recombination of S mu/S gamma and S gamma/S alpha.

Blood ◽  
1995 ◽  
Vol 86 (3) ◽  
pp. 949-957 ◽  
Author(s):  
I Dybedal ◽  
SE Jacobsen

Abstract Transforming growth factor beta (TGF-beta) is a bifunctional regulator of the growth of myeloid progenitors and is here demonstrated to directly inhibit the growth of primitive erythroid progenitors by 95% to 100% regardless of the cytokines stimulating growth. Autocrine TGF- beta production of primitive hematopoietic progenitors has previously been reported. In the present study, a neutralizing TGF-beta antibody (anti-TGF-beta) added to serum-containing cultures, resulted in a 3-, 4- , and 25-fold increase in burst-forming unit erythroid (BFU-E) colony formation in response to interleukin-4 (IL-4) plus erythropoietin (Epo), SCF plus Epo, and IL-11 plus Epo, respectively. The growth of BFU-E progenitors has been suggested to require a burst-promoting activity in addition to Epo. Accordingly, we observed no BFU-E colony formation in serum-containing cultures in response to Epo alone. In contrast, 50 BFU-E colonies were formed when anti-TGF-beta was included in the culture. In serum-free cultures, Epo also stimulated BFU-E colony formation in the absence of other cytokines, whereas anti-TGF- beta had no effect on the number of colonies formed. Quantitation of TGF-beta 1 in serum by an enzyme-linked immunosorbent assay method showed predominantly the presence of precursor (latent) TGF-beta 1, but also showed active TGF-beta 1 at a concentration sufficient to potently inhibit erythroid colony formation. Thus, neutralization of active TGF- beta 1 in serum shows that Epo alone is sufficient to stimulate the growth of murine BFU-E progenitors.


Blood ◽  
1995 ◽  
Vol 86 (3) ◽  
pp. 949-957 ◽  
Author(s):  
I Dybedal ◽  
SE Jacobsen

Transforming growth factor beta (TGF-beta) is a bifunctional regulator of the growth of myeloid progenitors and is here demonstrated to directly inhibit the growth of primitive erythroid progenitors by 95% to 100% regardless of the cytokines stimulating growth. Autocrine TGF- beta production of primitive hematopoietic progenitors has previously been reported. In the present study, a neutralizing TGF-beta antibody (anti-TGF-beta) added to serum-containing cultures, resulted in a 3-, 4- , and 25-fold increase in burst-forming unit erythroid (BFU-E) colony formation in response to interleukin-4 (IL-4) plus erythropoietin (Epo), SCF plus Epo, and IL-11 plus Epo, respectively. The growth of BFU-E progenitors has been suggested to require a burst-promoting activity in addition to Epo. Accordingly, we observed no BFU-E colony formation in serum-containing cultures in response to Epo alone. In contrast, 50 BFU-E colonies were formed when anti-TGF-beta was included in the culture. In serum-free cultures, Epo also stimulated BFU-E colony formation in the absence of other cytokines, whereas anti-TGF- beta had no effect on the number of colonies formed. Quantitation of TGF-beta 1 in serum by an enzyme-linked immunosorbent assay method showed predominantly the presence of precursor (latent) TGF-beta 1, but also showed active TGF-beta 1 at a concentration sufficient to potently inhibit erythroid colony formation. Thus, neutralization of active TGF- beta 1 in serum shows that Epo alone is sufficient to stimulate the growth of murine BFU-E progenitors.


1990 ◽  
Vol 265 (2) ◽  
pp. 1089-1093 ◽  
Author(s):  
P Kondaiah ◽  
M J Sands ◽  
J M Smith ◽  
A Fields ◽  
A B Roberts ◽  
...  

1988 ◽  
Vol 8 (5) ◽  
pp. 2229-2232 ◽  
Author(s):  
A M Brunner ◽  
L E Gentry ◽  
J A Cooper ◽  
A F Purchio

Analyses of cDNA clones coding for simian type 1 transforming growth factor beta (TGF-beta 1) suggest that there are three potential sites for N-linked glycosylation located in the amino terminus of the precursor region. Analysis of [3H]glucosamine-labeled serum-free supernatants from a line of Chinese hamster ovary cells which secrete high levels of recombinant TGF-beta 1 indicate that the TGF-beta 1 precursor, but not the mature form, is glycosylated. Digestion with neuraminidase resulted in a shift in migration of the two TGF-beta 1 precursor bands, which suggests that they contain sialic acid residues. Endoglycosidase H had no noticeable effect. Treatment with N-glycanase produced two faster-migrating sharp bands, the largest of which had a molecular weight of 39 kilodaltons. TGF-beta 1-specific transcripts produced by SP6 polymerase programmed the synthesis of a 42-kilodalton polypeptide which, we suggest, is the unmodified protein backbone of the precursor. Labeling with 32Pi showed that the TGF-beta 1 precursor was phosphorylated in the amino portion of the molecule.


1991 ◽  
Vol 173 (3) ◽  
pp. 589-597 ◽  
Author(s):  
G Poli ◽  
A L Kinter ◽  
J S Justement ◽  
P Bressler ◽  
J H Kehrl ◽  
...  

The pleiotropic immunoregulatory cytokine transforming growth factor beta (TGF-beta) potently suppresses production of the human immunodeficiency virus (HIV), the causative agent of the acquired immunodeficiency syndrome, in the chronically infected promonocytic cell line U1. TGF-beta significantly (50-90%) inhibited HIV reverse transcriptase production and synthesis of viral proteins in U1 cells stimulated with phorbol myristate acetate (PMA) or interleukin 6 (IL-6). Furthermore, TGF-beta suppressed PMA induction of HIV transcription in U1 cells. In contrast, TGF-beta did not significantly affect the expression of HIV induced by tumor necrosis factor alpha (TNF-alpha). These suppressive effects were not mediated via the induction of interferon alpha (IFN-alpha). TGF-beta also suppressed HIV replication in primary monocyte-derived macrophages infected in vitro, both in the absence of exogenous cytokines and in IL-6-stimulated cultures. In contrast, no significant effects of TGF-beta were observed in either a chronically infected T cell line (ACH-2) or in primary T cell blasts infected in vitro. Therefore, TGF-beta may play a potentially important role as a negative regulator of HIV expression in infected monocytes or tissue macrophages in infected individuals.


1991 ◽  
Vol 11 (10) ◽  
pp. 4952-4958
Author(s):  
A Zentella ◽  
F M Weis ◽  
D A Ralph ◽  
M Laiho ◽  
J Massagué

The growth-suppressive function of the retinoblastoma susceptibility gene product, RB, has been implicated in the mediation of growth inhibition and negative regulation of certain proliferation related genes by transforming growth factor-beta 1 (TGF-beta 1). Early gene responses to TGF-beta 1 were examined in order to determine their dependence on the cell cycle and on the growth-suppressive function of RB. TGF-beta 1, which rapidly elevates the steady-state level of junB and PAI-1 mRNAs and decreases that of c-myc mRNA, induces these responses in S-phase populations of Mv1Lu lung epithelial cells containing RB in a phosphorylated state. Since in this state RB is presumed to lack growth-suppressive activity, the response to TGF-beta 1 was also examined in DU145 human prostate carcinoma cells whose mutant RB product lacks growth-suppressive function. In these cells, TGF-beta 1 also decreases c-myc expression at the transcription initiation level. These results suggests that the c-myc, junB, and PAI-1 responses to TGF-beta 1 are not restricted to the G1 phase of the cell cycle and that down-regulation of c-myc expression by TGF-beta 1 can occur through a mechanism independent from the growth-suppressive function of RB.


1988 ◽  
Vol 91 (2) ◽  
pp. 313-318
Author(s):  
T. Lombardi ◽  
R. Montesano ◽  
M.B. Furie ◽  
S.C. Silverstein ◽  
L. Orci

Cultured endothelial cells isolated from fenestrated capillaries express many properties characteristic of their in vivo differentiated phenotype, including the formation of a limited number of fenestrae. In this study, we have investigated whether physiological factors that control cell differentiation might regulate the surface density of fenestrae in capillary endothelial cells. We have found that treatment of the cultures with retinoic acid (10 microM) induces a more than threefold increase in the surface density of endothelial fenestrae, whereas transforming growth factor beta (TGF beta) (2 ng ml-1) causes a sevenfold decrease in the surface density of these structures. These results show that the expression of endothelial fenestrae is susceptible to bidirectional modulation by physiological signals, and suggest that retinoids and TGF beta may participate in the regulation of fenestral density of capillary endothelium in vivo.


1991 ◽  
Vol 11 (10) ◽  
pp. 5338-5345
Author(s):  
B Kallin ◽  
R de Martin ◽  
T Etzold ◽  
V Sorrentino ◽  
L Philipson

By cDNA cloning and differential screening, five genes that are regulated by transforming growth factor beta (TGF beta) in mink lung epithelial cells were identified. A novel membrane protein gene, TI 1, was identified which was downregulated by TGF beta and serum in quiescent cells. In actively growing cells, the TI 1 gene is rapidly and transiently induced by TGF beta, and it is overexpressed in the presence of protein synthesis inhibitors. It appears to be related to a family of transmembrane glycoproteins that are expressed on lymphocytes and tumor cells. The four other genes were all induced by TGF beta and correspond to the genes of collagen alpha type I, fibronectin, plasminogen activator inhibitor 1, and the monocyte chemotactic cell-activating factor (JE gene) previously shown to be TGF beta regulated.


1991 ◽  
Vol 173 (5) ◽  
pp. 1121-1132 ◽  
Author(s):  
R A Fava ◽  
N J Olsen ◽  
A E Postlethwaite ◽  
K N Broadley ◽  
J M Davidson ◽  
...  

We have studied the consequences of introducing human recombinant transforming growth factor beta 1 (hrTGF-beta 1) into synovial tissue of the rat, to begin to better understand the significance of the fact that biologically active TGF-beta is found in human arthritic synovial effusions. Within 4-6 h after the intra-articular injection of 1 microgram of hrTGF-beta 1 into rat knee joints, extensive recruitment of polymorphonuclear leukocytes (PMNs) was observed. Cytochemistry and high resolution histological techniques were used to quantitate the influx of PMNs, which peaked 6 h post-injection. In a Boyden chamber assay, hrTGF-beta 1 at 1-10 fg/ml elicited a chemotactic response from PMNs greater in magnitude than that evoked by FMLP, establishing that TGF-beta 1 is an effective chemotactic agent for PMNs in vitro as well as in vivo. That PMNs may represent an important source of TGF-beta in inflammatory infiltrates was strongly suggested by a demonstration that stored TGF-beta 1 was secreted during phorbol myristate acetate-stimulated degranulation in vitro. Acid/ethanol extracts of human PMNs assayed by ELISA contained an average of 355 ng of TGF/beta 1 per 10(9) cells potentially available for secretion during degranulation of PMNs. [3H]Thymidine incorporation in vivo and autoradiography of tissue sections revealed that widespread cell proliferation was triggered by TGF-beta 1 injection. Synovial lining cells and cells located deep within the subsynovial connective tissue were identified as sources of at least some of the new cells that contribute to TGF-beta 1-induced hyperplasia. Our results demonstrate that TGF-beta is capable of exerting pathogenic effects on synovial tissue and that PMNs may represent a significant source of the TGF-beta present in synovial effusions.


Sign in / Sign up

Export Citation Format

Share Document