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T Hla

Publications and source records attributed to T Hla.

At least 55 records · Page 3Linked to original sources
PubMed1997

The mouse gene for the inducible G-protein-coupled receptor edg-1.

Edg-1, an immediate-early gene induced during the in vitro differentiation of human endothelial cells, encodes a G-protein-coupled receptor (GPR) that signals via the G(i)/mitogen-activated protein kinase (MAP kinase) pathway (Lee, M.-J., Evans, M., and Hla, T. (1996) J. Biol. Chem. 271, 11272-11279). It is a prototypical member of the subfamily of "orphan" receptors that are expressed in the cardiovascular and nervous systems. In this report, the mouse edg-1 gene was cloned and sequenced, and its expression patterns were defined. The edg-1 transcript was expressed in a wide variety of adult tissues including the brain, lung, liver, heart, and spleen. However, during embryogenesis, the edg-1 mRNA was induced late in development (after Embryonic Day 15.5) at centers of ossification. As a first step toward understanding the molecular basis of tissue-specific and inducible expression, the mouse edg-1 gene and its promoter were characterized. The mouse edg-1 gene is composed of two exons and is 4.9 kb in length. The second exon is large and contains the entire coding region and the 3'-untranslated region. The edg-1 promoter is TATA-less and contains GC-rich elements, and transcription initiation occurs from a single start site. The 5'-flanking region of the promoter contains several enhancer elements. However, the activity of the 5'-flanking region was suppressed by the repressor activity within the first intron. These data provide the basis for the further characterization of the regulation of the orphan GPR edg-1.

Amino Acid Sequence↗
PubMed1997

Involvement of nuclear factor kappa B in the regulation of cyclooxygenase-2 expression by interleukin-1 in rheumatoid synoviocytes.

OBJECTIVE: To evaluate involvement of the transcription factor nuclear factor kappa B (NF-kappa B) in the increased expression of cyclooxygenase-2 (COX-2) stimulated by interleukin-1 beta (IL-1 beta) in primary rheumatoid synoviocytes. METHODS: We treated early-passage rheumatoid synoviocytes with IL-1 beta and examined the time course of NF-kappa B translocation to the nucleus by Western blot analysis, as well as NF-kappa B binding to the COX-2 promoter/enhancer by electrophoretic mobility shift assay. We correlated the time course of NF-kappa B binding with expression of COX-2 messenger RNA (mRNA) and protein. Synoviocytes were then treated with either sense or antisense phosphorothioate-modified oligonucleotides derived from the transcription start site of the human NF-kappa B p65 RNA. We analyzed NF-kappa B binding to the COX-2 promoter and COX-2 protein levels after these treatments. RESULTS: IL-1 beta rapidly stimulated the translocation of the p65, p50, and c-rel NF-kappa B subunits from the cytoplasm to the nucleus. Electrophoretic mobility shift assay demonstrated binding to 2 NF-kappa B sites within the COX-2 promoter/enhancer, with a time course identical to that of nuclear localization of NF-kappa B. Supershift analysis revealed that binding activity was due primarily to the p65-p50 heterodimer and the p50 homodimer. With appropriate lag time after NF-kappa B binding, COX-2 mRNA and protein were increased. Pretreatment of RA synoviocytes with NF-kappa B p65 antisense oligonucleotides resulted in decreased binding to the COX-2 promoter and decreased COX-2 protein expression. CONCLUSION: These data demonstrate that signaling via the NF-kappa B pathway is involved in regulation of COX-2 expression induced by IL-1 beta in RA synoviocytes.

Arthritis, Rheumatoid↗
PubMed1996

Down-regulation of cytokine-induced cyclo-oxygenase-2 transcript isoforms by dexamethasone: evidence for post-transcriptional regulation.

The immediate-early cyclo-oxygenase-2 (Cox-2) gene encodes an inducible prostaglandin synthase enzyme that has been implicated in inflammatory and proliferative diseases. We have shown that the inflammatory cytokine interleukin-1 (IL-1) induces the Cox-2 gene in a sustained manner and that post-transcriptional mRNA stabilization is an important even [Ristimäki, Garfinkel, Wessendorf, Maciag and Hla (1994) J. Biol. Chem. 269, 11769-11775]. The anti-inflammatory glucocorticoid dexamethasone potently down-regulates IL-1-induced Cox-2 mRNA expression. Kinetic studies suggest that antagonism of IL-1-induced mRNA stabilization is, at least in part, responsible for the suppression of Cox-2 mRNA. The Cox-2 gene produces two major transcript isoforms, namely Cox-2(4.6) (4.6 kb) and Cox-2(2.8) (2.8 kb), which are derived by alternative polyadenylation in the 3'-untranslated region (UTR). In response to dexamethasone, the short Cox-2(2.8) transcript isoform, which lacks a highly conserved AU-rich region, decays with a longer half-life than the Cox-2(4.6) isoform. Furthermore, heterologous expression of the hybrid Cox-1 open reading frame and the Cox-2 3'-UTR results in the accumulation of high levels of the short isoform and lower levels of the long isoform. These data suggest that multiple elements in the 3'-UTR of the Cox-2 gene are involved in the determination of the differential mRNA stabilities of Cox-2 transcript isoforms. Because dexamethasone destabilizes the Cox-2 transcript, and because the decay of Cox-2 transcript isoforms induced by dexamethasone occurs with different half-lives, post-transcriptional mRNA destabilization may be an important mechanism in the action of anti-inflammatory glucocorticoids.

Base Sequence↗
PubMed1996

The inducible G protein-coupled receptor edg-1 signals via the G(i)/mitogen-activated protein kinase pathway.

The edg-1 gene encodes an inducible G protein-coupled receptor (GPR) homologue that is induced during the in vitro differentiation of human endothelial cells. The aim of this study was to investigate the G protein-coupling and -signaling properties of the edg-1 polypeptide. The third cytosolic loop (i3) of edg-1 associates with G(i) alpha and G(o) alpha polypeptides in a guanosine 5'-O-(thiotriphosphate)-sensitive manner. Immunoprecipitation of the edg-1 polypeptide in transfected cells results in the co-precipitation of G(i) alpha 1 and G(i) alpha 3 polypeptides. These data strongly suggest that edg-1 is capable of coupling to the Gi pathway. Overexpression of the edg-1 GPR in human embryonic kidney 293 cells results in the sustained activation of the MAP kinase activity that is blocked by pertussis toxin treatment. Moreover, NIH3T3 cells permanently transfected with edg-1 exhibit enhanced MAP kinase and phospholipase A2 activities. These data suggest that the G(i)/mitogen-activated protein kinase pathway is a major signaling pathway regulated by the orphan receptor edg-1.

3T3 Cells↗
PubMed1996

Molecular characterization of the 5.2 KB isoform of the human cyclooxygenase-1 transcript.

Several cDNA clones from human endothelial cells were isolated by expression cloning with the polyclonal antisera against the Ram seminal vesicle cyclooxygenase enzyme (Cox-1). One such clone produced a fusion protein that reacted with two other Cox-1 antiserum (Hla, T., Farrell, M.P., Kumar, A. and Bailey, J.M. (1986) Prostaglandins 32 (6) 829-845). The 2.5 kb cDNA insert was sequenced and contained 60 bp encoding the C-terminal end of the human Cox-1 polypeptide, followed by 2.3 kb of untranslated region. Northern blot analysis of human endothelial cells using the 2.5 kb cDNA insert detected the 2.8 and 5.2 kb Cox-1 transcripts. These data indicated that the isolated clone represented the 5.2 kb isoform of the human Cox-1 mRNA. The presence of the canonical polyadenylation site AAUAAA at 740 bp downstream from the translation termination codon suggests that alternative polyadenylation of the Cox-1 gene gives rise to 5.2 and 2.8 kb isoforms. The sequence of the 3'-UTR of the Cox-1 transcripts is highly divergent from that of the human Cox-2 transcript isoforms, suggesting a distinct function in the regulation of expression at the post-transcriptional and/or translational levels.

Amino Acid Sequence↗
PubMed1995

Induction of vascular endothelial growth factor expression in synovial fibroblasts by prostaglandin E and interleukin-1: a potential mechanism for inflammatory angiogenesis.

Inflammatory mediators such as prostaglandin E2 (PGE2) and interleukin-1 (IL-1) induce angiogenesis by yet undefined mechanisms. We demonstrate that PGE2 and IL-1 induces the expression of vascular endothelial growth factor (VEGF), a selective angiogenic factor by rheumatoid synovial fibroblast cells. Transcripts for the EP1 and EP2 subtypes of PGE receptors are expressed in synovial fibroblasts. Activators of protein kinase A pathway stimulated the expression of VEGF whereas down-regulation of protein kinase C did not influence the PGE effect, suggesting that signalling from the EP2 receptor via the protein kinase A pathway is important. The induction of VEGF expression by PGE2 and interleukin-1 alpha may be an important mechanism in inflammatory angiogenesis.

Arthritis, Rheumatoid↗
PubMed1995

Expression of cyclooxygenase-1 and -2 in human colorectal cancer.

Several studies indicate that nonsteroidal anti-inflammatory drugs including indomethacin, aspirin, sulindac, and piroxicam reduce the risk of colon cancer. Furthermore, nonsteroidal anti-inflammatory drugs that inhibit the cyclooxygenase (COX) enzyme were shown to inhibit the development of colon cancer in animal models of carcinogenesis. Non-steroidal anti-inflammatory drugs inhibit the enzymatic activity of both the constitutive (COX-1) and inducible (COX-2) isoforms of COX enzyme. We have investigated the expression of COX-1 and COX-2 polypeptides in human colon cancer tissues using immunohistochemistry. Enhanced COX-2 expression was observed in colon cancer tissues from 15 subjects with clinically diagnosed colorectal cancer. Marked COX-2 expression was observed in cancer cells, inflammatory cells, vascular endothelium, and fibroblasts of the lesional tissues compared with the nonlesional and normal colon tissues. The extent and intensity of the immunoreactive COX-2 in cancer cells was much greater than that of the other cell types. In contrast, the expression of COX-1 polypeptide was weak in both normal and cancerous specimens. These data suggest that the enhanced expression of the COX-2 gene in colon cancer tissues may contribute to the enhanced synthesis of prostaglandin E2 by the colon cancer tissues. Enhanced expression of COX-2 may play a role in the pathogenesis of colon cancer. Furthermore, selective inhibition of COX-2 may prove to be more efficacious in the retardation of colon cancer development.

Adenocarcinoma↗
PubMed1995

Characterization of edg-2, a human homologue of the Xenopus maternal transcript G10 from endothelial cells.

We have isolated by polymerase chain reaction-amplified subtractive hybridization technique, several cDNA clones that are induced by phorbol myristic acetate in human umbilical vein endothelial cells (HUVEC). One such clone, termed edg-2, was sequenced and was found to encode a human homologue of a Xenopus maternal transcript G10. The deduced amino acid sequence of edg-2 contains a putative nuclear translocation sequence, an N-terminal acidic domain and a cysteine-rich C-terminal domain containing a putative Zinc-finger structure. The structure of edg-2 polypeptide suggests that it may be a nuclear regulator of transcription. The edg-2 mRNA was expressed ubiquitously in cell lines of epithelial and mesenchymal lineages. In addition, the edg-2 polypeptide sequence is highly conserved in evolution and is expressed by lower organisms such as yeast and C. elegans, suggesting that it may be an important regulator of general nuclear function.

Amino Acid Sequence↗
PubMed1994

Structure of the human cyclo-oxygenase-2 gene.

Cyclo-oxygenase (Cox), a rate-limiting enzyme in the synthesis of prostanoids, is encoded by two genes, Cox-1 and Cox-2, which are differentially expressed and regulated. Human Cox-1 and -2 polypeptides share 61% primary sequence identity. While the expression of Cox-1 is maximal in quiescent cells. Cox-2 expression is induced by growth factors and cytokines. We have screened a human genomic library with a probe from the 5'-untranslated region (UTR) of the human Cox-2 (hCox-2) cDNA and isolated two overlapping genomic clones. We have determined the DNA sequence of 0.8 kb upstream of the transcription start site, 6 kb of protein coding region, which includes 10 exons and 9 introns, as well as 2.5 kb of the 3'-UTR. The structures of the hCox-1 and hCox-2 and the murine TIS10 (Cox-2) genes are highly conserved, with a few exceptions. The 3'-UTRs of the Cox-1 and -2 genes are distinct; for example, the largest exon in the Cox-2 gene encodes the entire 3'-UTR, containing 22 copies of the 'AUUUA' RNA instability element. Sequence analysis of the 5'-flanking region has shown several potential transcription regulatory sequences, including a TATA box, a C/EBP motif, two AP-2 sites, three SP1 sites, two NF-kappa B sites, a CRE motif and an Ets-1 site. These efforts serve as a basis for future studies on transcriptional and post-transcriptional mechanisms of Cox-2 gene regulation.

Amino Acid Sequence↗
PubMed1994

Induction of cyclooxygenase-2 by interleukin-1 alpha. Evidence for post-transcriptional regulation.

Prostanoids, produced by diverse cell types, modulate a variety of pathophysiological processes. The rate of prostanoid synthesis is determined, in part, by the levels of prostanoid-synthetic enzymes, such as cyclooxygenase (Cox), a rate-limiting enzyme in the conversion of arachidonic acid to prostanoids. While two Cox genes have been identified, Cox-2 is unique because it is highly induced in response to cell activation processes including inflammation. We have studied the effect of interleukin-1 alpha (IL-1 alpha), a proinflammatory cytokine that facilitates its actions in part by inducing the synthesis of prostanoids, on the expression of Cox-2 in a human cell line (ECV304) and demonstrated that IL-1 alpha induces a sustained increase in the expression of the Cox-2 mRNA as well as the functional enzyme. Three mechanistically distinct inhibitors of translation stimulated the expression of the Cox-2 mRNA and potentiated the effect of IL-1 alpha. Furthermore, IL-1 alpha induced rapid but transient activation of Cox-2 transcription and, in the absence of transcription, prolonged the half-life of the Cox-2 mRNA. Together, these data suggest that post-transcriptional mechanisms are important in the sustained induction of the Cox-2 mRNA and that IL-1 alpha may increase the stability of the Cox-2 transcript.

Base Sequence↗
PubMed1994

Cyclooxygenase-1 and -2 expression in rheumatoid synovial tissues. Effects of interleukin-1 beta, phorbol ester, and corticosteroids.

High levels of immunoreactive cyclooxygenase (Cox; prostaglandin H synthase) are present in synovia from patients with rheumatoid arthritis (RA). We now show that the recently identified inducible isoform of Cox, Cox-2, is expressed in synovia from patients with RA. To further explore modulation of the Cox isoforms in RA synovial tissues, we examined the expression and modulation of Cox-1 and -2 in rheumatoid synovial explant cultures and cultured rheumatoid synovial fibroblast-like cells (synoviocytes). Immunoprecipitation of in vitro labeled proteins and Western blot analysis demonstrated the presence of both Cox-1 and -2 under basal conditions in freshly explanted rheumatoid synovial tissues. De novo synthesis of Cox-2 polypeptide was enhanced by IL-1 beta or PMA, and dramatically suppressed by dexamethasone (dex). Cox-1 expression, under the same conditions, showed only minor variation. Since mRNA for Cox-2 is highly unstable, we examined the regulation of Cox-2 transcripts in cultured rheumatoid synoviocytes. Under basal conditions both Cox-1 and -2 mRNAs were present at low levels, but Cox-2 mRNA was markedly increased by treatment with IL-1 beta or PMA. dex markedly suppressed the induction of Cox-2 mRNA. In sharp contrast, Cox-1 transcripts were not modulated by IL-1 beta or dex. These data suggest that modulation of Cox-2 expression by IL-1 beta and corticosteroids may be an important component of the inflammatory process in synovial tissues from patients with RA.

Adrenal Cortex Hormones↗
PubMed1994

Differential inhibition of human prostaglandin endoperoxide H synthases-1 and -2 by nonsteroidal anti-inflammatory drugs.

We developed an in vitro expression system for accurate kinetic analyses of the inhibition of the human prostaglandin H synthase isozymes (hPGHS-1 and -2) by nonsteroidal anti-inflammatory drugs (NSAIDs). Assays of instantaneous inhibition in which enzyme, 10 microM arachidonate, and an NSAID were mixed simultaneously were used to determine apparent affinities of 14 common NSAIDs for hPGHS-1 and hPGHS-2. All NSAIDs except salicylate had appreciable apparent affinities (IC50 < or = 100 microM) for hPGHS-1. Most NSAIDs also exhibited appreciable affinities toward hPGHS-2, but three prominent exceptions were indomethacin, piroxicam and phenylbutazone. We subsequently performed measurements of time-dependent inhibition in which either (a) enzyme and an NSAID were preincubated before substrate was added to initiate the reactions or (b) recovery of activity after time-dependent inhibition was measured using intact cells preincubated with various NSAIDs. Indomethacin, flurbiprofen, meclofenamate and diclofenac, but not ibuprofen, piroxicam or phenylbutazone, caused time-dependent inhibition of both hPGHS-1 and -2 in vitro. For cells pretreated with flurbiprofen or meclofenamate, hPGHS-2 activities, but not hPGHS-1 activities, were recovered relatively rapidly; with indomethacin, recoveries of hPGHS-1 and hPGHS-2 activities were both slow. hPGHS-2 is thought to be the target of NSAIDs acting as anti-inflammatory agents. However, our results indicate that neither measurements of affinities of NSAIDs for hPGHS-2 conducted in vitro with 10 microM arachidonate nor measurements of time-dependent inhibition of hPGHS-2 always predict whether a compound (e.g., piroxicam or phenylbutazone) has anti-inflammatory activity in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

Coexpression of phosphotyrosine-containing proteins, platelet-derived growth factor-B, and fibroblast growth factor-1 in situ in synovial tissues of patients with rheumatoid arthritis and Lewis rats with adjuvant or streptococcal cell wall arthritis.

Fibroblast growth factor (FGF)-1 and PDGF-B-like factors have been implicated in the pathobiology of RA and animal models of this disease. Since the receptors for FGF-1 and PDGF are tyrosine kinases, we examined the expression of tyrosine phosphorylated proteins (phosphotyrosine, P-Tyr) in synovial tissues from patients with RA and osteoarthritis (OA), and rats with streptococcal cell wall (SCW) and adjuvant arthritis (AA). Synovia from patients with RA and LEW/N rats with SCW and AA arthritis, in contrast to controls, stained intensely with anti-P-Tyr antibody. The staining colocalized with PDGF-B and FGF-1 staining. Comparative immunoblot analysis showed markedly enhanced expression of a 45-kD P-Tyr protein in the inflamed synovia. Treatment with physiological concentrations of dexamethasone suppressed both arthritis and P-Tyr expression in AA. P-Tyr was only transiently expressed in athymic nude Lewis rats and was not detected in relatively arthritis-resistant F344/N rats. These data suggest that (a) FGF-1 and PDGF-B-like factors are upregulated and may induce tyrosine phosphorylation of proteins in vivo in inflammatory joint diseases, (b) persistent high level P-Tyr expression is T lymphocyte dependent, correlates with disease severity, and is strain dependent in rats, (c) corticosteroids, in physiological concentrations, downregulate P-Tyr expression in these lesions.

Animals↗
PubMed1992

Human cyclooxygenase-2 cDNA.

Cyclooxygenase (Cox), also known as prostaglandin (PG) H synthase (EC 1.14.99.1), catalyzes the rate-limiting step in the formation of inflammatory PGs. A major regulatory step in PG biosynthesis is at the level of Cox: growth factors, cytokines, and tumor promoters induce Cox activity. We have cloned the second form of the Cox gene (Cox-2) from human umbilical vein endothelial cells (HUVEC). The cDNA encodes a polypeptide of 604 amino acids that is 61% identical to the previously isolated human Cox-1 polypeptide. In vitro translation of the human (h)Cox-2 transcript in rabbit reticulocyte lysates resulted in the synthesis of a 70-kDa protein that is immunoprecipitated by antiserum to ovine Cox. Expression of the hCox-2 open reading frame in Cos-7 monkey kidney cells results in the elaboration of cyclooxygenase activity. hCox-2 cDNA hybridizes to a 4.5-kilobase mRNA species in HUVEC, whereas the hCox-1 cDNA hybridizes to 3- and 5.3-kilobase species. Both Cox-1 and Cox-2 mRNAs are expressed in HUVEC, vascular smooth muscle cells, monocytes, and fibroblasts. Cox-2 mRNA was preferentially induced by phorbol 12-myristate 13-acetate and lipopolysaccharide in human endothelial cells and monocytes. Together, these data demonstrate that the Cox enzyme is encoded by at least two genes that are expressed and differentially regulated in a variety of cell types. High-level induction of the hCox-2 transcript in mesenchymal-derived inflammatory cells suggests a role in inflammatory conditions.

Amino Acid Sequence↗
PubMed1992

In vivo cyclooxygenase expression in synovial tissues of patients with rheumatoid arthritis and osteoarthritis and rats with adjuvant and streptococcal cell wall arthritis.

Cyclooxygenase (COX), or prostaglandin (PG) H synthase, plays a role in inflammatory diseases, but very limited data exist on the regulation of COX in vivo. We, therefore, studied the in vivo expression of COX in synovia from patients with rheumatoid arthritis (RA) and osteoarthritis (OA), as well as joints of rats with streptococcal cell wall (SCW) and adjuvant arthritis. Extensive and intense intracellular COX immunostaining, which correlated with the extent and intensity of mononuclear cell infiltration, was observed in cells throughout RA synovia. Significantly less or equivocal staining was noted in OA and normal human synovia. Similarly, COX immunostaining was equivocal in the joints of normal and arthritis-resistant F344/N rats. In contrast, high level expression developed rapidly in euthymic female Lewis (LEW/N) rats throughout the hindlimb joints and overlying tissues including skin, preceding or paralleling clinically apparent experimental arthritis. COX was expressed in the joints of athymic LEW.rnu/rnu rats 2-4 d after injection of SCW or adjuvant but was not sustained. Physiological doses of antiinflammatory glucocorticoids, but not progesterone, suppressed both arthritis and COX expression in LEW/N rats. These observations suggest that, in vivo, (a) COX expression is upregulated in inflammatory joint diseases, (b) the level of expression is genetically controlled and is a biochemical correlate of disease severity, (c) sustained high level up-regulation is T cell dependent, and (d) expression is down-regulated by antiinflammatory glucocorticoids.

Animals↗
PubMed1991

Cyclooxygenase gene expression is down-regulated by heparin-binding (acidic fibroblast) growth factor-1 in human endothelial cells.

The expression of cyclooxygenase (EC 1.14.99.1, Cox), a rate-limiting enzyme in the biosynthesis of inflammatory prostanoids, is regulated by growth factors and cytokines. We have shown previously that the cytokine interleukin-1, an inhibitor of endothelial growth in vitro and stimulator of prostacyclin production, induces the expression of the 3-kilobase Cox transcript in cultured human umbilical vein endothelial cells (HUVEC). In contrast, the endothelial cell mitogen, heparin-binding (acidic fibroblast) growth factor-1 (HBGF-1) inhibits the synthesis of prostacyclin in HUVEC. In this report, we describe the effect of HBGF-1 on Cox mRNA expression in HUVEC. Cells cultured in the presence of HBGF-1 express diminished Cox mRNA levels whereas quiescent cells maintained in serum expressed a 7-fold higher level of the transcript for Cox. Concomitantly, the level of the Cox translation product and prostacyclin synthesis are also reduced by HBGF-1. Further, HBGF-1, in the presence of heparin, down-regulates the levels of the Cox transcript in a dose- and time-dependent manner. The onset of action of HBGF-1 is slow, requiring up to 24 h to depress the level of Cox mRNA. Lastly, the effective dose of HBGF-1 to depress Cox mRNA levels is similar to that required for mitogenesis, suggesting that cell proliferation may be required for the reduction of Cox expression in vitro. Thus, Cox may belong to a class of genes that are reversibly down-regulated during periods of endothelial cell proliferation.

Base Sequence↗
PubMed1991

Cytotoxic activity of chimeric proteins composed of acidic fibroblast growth factor and Pseudomonas exotoxin on a variety of cell types.

Chimeric proteins composed of acidic fibroblast growth factor (acidic FGF) and several forms of Pseudomonas exotoxin (PE) that cannot bind to the PE receptor have been produced in Escherichia coli by expressing chimeric genes in which DNA encoding acidic FGF is fused to various mutant forms of PE. These acidic FGF-PE fusion proteins were found to be cytotoxic to a variety of tumor cell lines including hepatocellular (PLC/PRF/5 and HEPG2), prostatic (LNCaP), colon (HT29), and breast (MCF-7) carcinomas at concentrations of 1-70 ng/ml. The cytotoxic effects of acidic FGF-PE were FGF-receptor specific as demonstrated by competition with excess acidic FGF and by showing that acidic FGF-PE bound to the FGF receptor with the same affinity as acidic FGF. Furthermore, the cell-killing activity of acidic FGF-PE was toxin-mediated, as an acidic FGF-PE mutant, which does not possess ADP-ribosylation activity, failed to kill cells. These findings demonstrate that acidic FGF-PE is a potent cytotoxic molecule that can be targeted to FGF receptor-bearing cells. Because acidic FGF is a potent angiogenic molecule, cytotoxic acidic FGF-PE chimeras may have utility as anti-angiogenic agents. These molecules could be helpful in determining the functional role of FGF receptors in cellular processes.

ADP Ribose Transferases↗