Biomedical subjects

J E Kudlow

Publications and source records attributed to J E Kudlow.

At least 37 records · Page 2Linked to original sources

PubMed1997

Transcription factor AP-2 controls transcription of the human transforming growth factor-alpha gene.

The epidermal growth factor receptor is vital for normal development and plays a role in oncogenesis. The level of activation of this receptor by transforming growth factor-alpha (TGF-alpha) is controlled, in part, by the rate of transcription of the TGF-alpha gene. In the characterization of the proximal TGF-alpha promoter by DNase I footprinting, a 43-base pair element (-88 to -130 relative to the transcription start site), designated TalphaRE I, was found that was specifically protected by nuclear proteins from human mammary carcinoma MDA468 cells. TalphaRE I was essential for the maximal expression of the TGF-alpha gene as indicated by deletion and mutagenesis analyses. TalphaRE I consists of two cis-acting elements, a proximal regulatory element (PRE, -89 to -103) and a distal regulatory element (DRE, -121 to -128). Both elements were able to form specific complexes with protein from MDA468 cell nuclear extracts and are necessary for the full activity of the entire 1.1-kilobase pair TGF-alpha promoter. Competition and antibody studies determined that the DRE contains a binding site for the transcription factor AP-2, while the protein that binds to the PRE has yet to be identified. When linked upstream to the heterologous herpes simplex thymidine kinase promoter, the TalphaRE I enhanced transcription up to 11-fold in MDA468 cells. Cotransfection of an AP-2 expression vector was able to activate transcription from the TalphaREI-TK construct in a DRE-dependent manner. These results further our understanding of how TGF-alpha transcription is regulated.

Base Sequence↗

PubMed1997

Cloning and partial characterization of the mouse glutamine:fructose-6-phosphate amidotransferase (GFAT) gene promoter.

Glutamine:fructose-6-phosphate amidotransferase (GFAT) is the enzyme that is rate limiting in the synthesis of glucosamine and hexosamines. Glucosamine has been proposed to contribute to the glucotoxicity of diabetes. Evidence that the gene encoding GFAT is transcriptionally regulated prompted us to clone and characterize its promoter. The position of the mouse GFAT promoter relative to the translational start site was located by primer extension and found to be 149 bp upstream of the translational start site. A 1.9 kb SacI fragment of the GFAT gene was found to contain the promoter and 88 bp of sequence downstream of the transcriptional start site. This promoter segment could drive expression of a luciferase reporter gene, could confer correct transcriptional initiation to the reporter and could confer the EGF-responsiveness previously observed in the native gene. The mouse GFAT promoter lacks a canonical TATA box and has several GC boxes within a highly GC-rich region. Deletional analysis of the promoter indicated that a proximal element extending to -120 relative to the transcriptional start site could confer reporter expression at a level of 57% of the 1.9 kb construct. Detailed analysis of this proximal region by DNase I footprinting, electrophoretic mobility shift assays and site-directed mutagenesis indicated that Sp1 binds to three elements in this proximal promoter segment and plays a vital role in regulation of transcription from this gene.

3T3 Cells↗

PubMed1997

O glycosylation of an Sp1-derived peptide blocks known Sp1 protein interactions.

The O-linked N-acetylglucosamine (O-GlcNAc) modification of proteins is dynamic and abundant in the nucleus and cytosol. Several transcription factors, including Sp1, have been shown to contain this modification; however, the functional role of O-GlcNAc in these proteins has not been determined. In this paper we describe the use of the previously characterized glutamine-rich transactivation domain of Sp1 (B-c) as a model to investigate the role of O-GlcNAc in Sp1's transcriptionally relevant protein-to-protein interactions with the TATA-binding-protein-associated factor (TAF110) and holo-Sp1. When the model Sp1 peptide was overexpressed in primate cells, this 97-amino-acid domain of Sp1 was found to contain a dominant O-GlcNAc residue at high stoichiometry, which allowed the mapping and mutagenesis of this glycosylation site. In vitro interaction studies between this segment of Sp1 and Drosophila TAF110 or holo-Sp1 indicate that the O-GlcNAc modification functions to inhibit the largely hydrophobic interactions between these proteins. In HeLa cells, the mutation at the mapped glycosylation site was permissive for transcriptional activation. We propose the hypothesis that the removal of O-GlcNAc from an interaction domain can be a signal for protein association. O-GlcNAc may thereby prevent untimely and ectopic interactions.

Amino Acid Sequence↗

PubMed1997

Reduced O glycosylation of Sp1 is associated with increased proteasome susceptibility.

Sp1 is a ubiquitously expressed transcription factor that is particularly important for the regulation of TATA-less genes that encode housekeeping proteins. Most growth factors and receptors are also encoded by such genes. Sp1 is multiply O glycosylated by covalent linkage of the monosaccharide N-acetylglucosamine (O-GlcNAc) to serine and threonine residues. Based on an earlier observation that growth factor gene transcription can be regulated by glucose and glucosamine in vascular smooth muscle cells, we determined whether Sp1 glycosylation could be regulated and if this modification altered Sp1 function. We found that Sp1 becomes hyperglycosylated when cells are exposed to 5 mM glucosamine, whereas under glucose starvation, stimulation with cyclic AMP (cAMP) results in nearly complete deglycosylation of this protein. Correlating with this hypoglycosylated state, Sp1 is rapidly proteolytically degraded by an enzyme(s) that can be inhibited by specific proteasome inhibitors, lactacystin and LLnL. Treatment of cells with glucose or glucosamine protects Sp1 from cAMP-mediated degradation, whereas blockade of glucosamine synthesis abrogates glucose but not glucosamine protection. This effect on Sp1 is specific, in that the Stat-3 and E2F transcription factors did not undergo degradation under these conditions. The O-GlcNAc modification of Sp1 may play a role as a nutritional checkpoint. In the absence of adequate nutrition, Sp1 becomes hypoglycosylated and thereby subject to proteasome degradation. This process could potentially result in reduced general transcription, thereby conserving nutrients.

Animals↗

PubMed1997

Targeted expression of a dominant negative epidermal growth factor receptor in the mammary gland of transgenic mice inhibits pubertal mammary duct development.

The epidermal growth factor (EGF) system has been thought to play an important role in normal mammary development and carcinogenesis. To study the role of the EGF receptor (EGFR) in mammary development, we developed a transgenic mouse model in which a C-terminal truncated mouse EGFR (EGFR-TR) was expressed in the mouse mammary epithelium under the control of the mouse mammary tumor virus long terminal repeat. The EGFR-TR lacks most of the cytoplasmic domain of the receptor, including the entire protein tyrosine kinase domain. In cultured cells, we show that it acts in a dominant negative manner in EGF-signaled EGFR autophosphorylation. Several lines of mice were characterized and shown to express the transgene at the mRNA and protein levels not only in the mammary gland but also in the salivary glands, epididymis, and prostate. In postpubertal virgin female mice, the expression of the EGFR-TR in the mammary glands was greater than the expression of the endogenous wild type EGFR. In these virgin mice, inhibition in mammary ductal development and a decrease of mammary epithelial DNA synthesis were observed beginning at 5-6 weeks. The inhibition of duct development was most apparent by 15-16 weeks, resulting in a significant defect in ductal branching and outgrowth and an apparent overall decrease in the size of the mammary glands. However, during pregnancy, expression of the endogenous wild type EGFR was markedly increased relative to the EGFR-TR and, at this stage, normal presecretory alveoli developed from the hypoplastic duct tree. Postpartum, normal lactation occurred. Despite EGFR-TR expression in other tissues, no morphological abnormalities were observed. This model demonstrates that the EGFR-TR behaves as a dominant negative regulator of the EGFR system in vivo and that the EGFR system plays an important role in mammary ductal development.

Aging↗

PubMed1996

Glucose metabolism to glucosamine is necessary for glucose stimulation of transforming growth factor-alpha gene transcription.

Transforming growth factor-alpha (TGFalpha) gene transcription can be increased when arterial smooth muscle cells are exposed to supraphysiological concentrations of glucose, and this effect of glucose can be mimicked by glucosamine. To determine whether the metabolism of glucose to glucosamine is required for this glucose effect, the rate-limiting step in glucose metabolism to glucosamine through the enzyme glutamine:fructose-6-phosphate amidotransferase (GFAT) was blocked using pharmacological and antisense strategies. We found that blockage of GFAT activity or expression significantly blunted the glucose-induced increase of TGFalpha expression. Blockage of GFAT also resulted in a decreased RL2 signal on intracellular proteins as detected by Western blotting and indirect immunofluorescence. The RL2 monoclonal antibody recognizes an epitope on proteins that contain N-acetylglucosamine and thus is a measure of protein glycosylation. Conversely, treatment of the cells with glucose and glucosamine resulted in an increase in the RL2 epitope on intracellular proteins. These results indicate that the metabolism of glucose to glucosamine is necessary for the transcriptional stimulation of TGFalpha expression in vascular smooth muscle cells by glucose. Furthermore, the level of glycosylation of some intracellular proteins can be modulated in response to physiological changes in the extracellular glucose concentration and the net activity of GFAT.

Animals↗

PubMed1996

The role of the transcription factor Sp1 in regulating the expression of the WAF1/CIP1 gene in U937 leukemic cells.

The Waf1/Cip1 protein induces cell cycle arrest through inhibition of the activity of cyclin-dependent kinases and proliferating cell nuclear antigen. Expression of the WAF1/CIP1 gene is induced in a p53-dependent manner in response to DNA damage but can also be induced in the absence of p53 by agents such as growth factors, phorbol esters, and okadaic acid. WAF1/CIP1 expression in U937 human leukemic cells is induced by both phorbol ester, a protein kinase C activator, and by okaidaic acid, an inhibitor of phosphatases 1 and 2A. Both of these agents induce the differentiation of these leukemic cells toward macrophages. We demonstrate that phorbol esters and okadaic acid stimulate transcription from the WAF1/CIP1 promoter in U937 cells. This transcription is mediated by a region of the promoter between -154 and +16, which contains two binding sites for the transcription factor Sp1. Deletion or mutation of these Sp1 sites reduces WAF1/CIP1 promoter response to phorbol ester and okadaic acid, while a reporter gene under the control of a promoter containing only multiple Sp1 binding sites and a TATA box is induced by phorbol ester and okadaic acid. The WAF1/CIP1 promoter is also highly induced by exogenous Sp1 in the Sp1-deficient Drosophila Schnieder SL 2 cell line. These results suggest that phorbol ester and okadaic acid activate transcription of the WAF1/CIP1 promoter through a complex of proteins that includes Sp1 and basal transcription factors.

Base Sequence↗

PubMed1996

Role of glucosamine synthesis in the stimulation of TGF-alpha gene transcription by glucose and EGF.

Transforming growth factor-alpha (TGF-alpha) gene transcription is regulated by both epidermal growth factor (EGF) and glucose. Previous studies have suggested that the metabolism of glucose to glucosamine through the enzyme L-glutamine: D-fructose-6-phosphate amidotransferase (GFAT) plays a critical role in the glucose signaling. In this paper, we compared the role of GFAT in the glucose and EGF signals. We found that, although EGF stimulates GFAT mRNA accumulation in MDA-MB-468 cells, this effect of EGF occurred several hours after TGF-alpha transcription increased. MDA-MB-468 cells also exhibited a TGF-alpha transcriptional response to low concentrations of glucose. The TGF-alpha response to glucose but not EGF could be inhibited by a blocker of GFAT activity. Blockade of GFAT was confirmed by using Western blotting with the RL2 antibody, which recognizes an epitope on proteins containing N-acetylglucosamine. Exposure of cells to glucose increased the RL2 signal on several polypeptides, but this change could be blocked by inhibition of GFAT. These results support the notion that glucose stimulation of TGF-alpha expression requires GFAT, but EGF stimulation does not.

Animals↗

PubMed1995

Sequence of the functional human keratin K14 promoter.

The K14 keratin is an intermediate filament produced in squamous epithelia. This tissue-specific expression is directed by the promoter (pK14) of the K14 gene which has been used extensively to direct the expression of transgenes to the skin. Human K14 was cloned and the upstream sequence is presented. In transient transfections, pK14 directs expression of a luciferase reporter in keratinocytes much more potently than in breast cancer cells.

Base Sequence↗

PubMed1995

p53 stimulates transcription from the human transforming growth factor alpha promoter: a potential growth-stimulatory role for p53.

Physical and chemical agents can damage the genome. Part of the protective response to this damage is the increased expression of p53. p53, a transcription factor, controls the expression of genes, leading to cell cycle arrest and apoptosis. Another protective mechanism is the proliferative response required to replace the damaged cells. This proliferation is likely to be signaled by growth factors. In this communication, we show that the transforming growth factor alpha (TGF-alpha) gene is a direct target for p53-mediated transcriptional activation. In a stable cell line containing an inducible p53 construct, p53 induction leads to a threefold accumulation of the native TGF-alpha mRNA. IN cotransfection assays using a TGF-alpha promoter reporter construct, we show that expression of wild-type but not mutant p53 increases transcriptional activity of the TGF-alpha promoter by approximately 2.5-fold. In vitro, wild-type p53 binds to a consensus binding site found in the proximal portion of the promoter, and this sequence is necessary for the p53 transcriptional response. Furthermore, this element confers p53 induction to the otherwise nonresponsive adenovirus major late promoter. In addition to these results, we found that the TGF-alpha promoter contains a nonconsensus but functional TATA box-binding protein-binding site approximately 30 bp upstream of the transcription start site. Although p53 can repress transcription from promoters containing a TATA box, the nonconsensus TGF-alpha TATA motif is resistant to this effect. On the basis of these results, we propose that p53 may play a dual role, which includes both the elimination of irreparably genetically damage cells and the proliferative response necessary for their replacement, in the response to physical-chemical damage.

Adenoviridae↗

PubMed1995

Targeting of transforming growth factor-alpha expression to pituitary lactotrophs in transgenic mice results in selective lactotroph proliferation and adenomas.

The PRL-secreting cells of the pituitary gland normally express transforming growth factor-alpha (TGF alpha). To determine the effect of increasing TGF alpha expression in the pituitary, a transgenic mouse model was created in which overexpression of human TGF alpha was directed to the pituitary lactotrophs using the rat PRL promoter. Of the four gene-positive mouse lines, two expressed the messenger RNA corresponding to the transgenic in the pituitary glands. However, in both these lines, expression could only be detected in the female animals. Expression of the transgenic could be detected as early as 1 month of age, but no pathology or developmental abnormalities were detected until the animals reached 6 months, at which time, hyperplasia of the lactotrophs. By the age of 12 months, all of the homozygous transgenic females had developed pituitary adenomas that were immunopositive for PRL. The other hormone-producing cells of the pituitary showed no obvious pathology. The male transgenics developed neither hyperplasia nor adenomas, nor did the gene-positive transgenic lines that did not express the transgene. In no case was an aggressive pituitary tumor seen. This transgenic mouse model indicates that TGF alpha overexpression by lactotrophs stimulates the growth of these pituitary cells. Furthermore, TGF alpha has a highly localized action in the pituitary gland, resulting only in lactotroph hyperplasia and prolactinomas. These observations suggest that TGF alpha might play a role in the development of prolactinomas.

Animals↗

PubMed1995

Regulation of glutamine:fructose-6-phosphate amidotransferase gene transcription by epidermal growth factor and glucose.

In preparation for the cellular proliferation stimulated by growth factors, the rate of macromolecular synthesis must be increased to allow for the enlargement of the cell that proceeds mitosis. The increased glycoprotein synthesis that follows growth factor stimulation would consume the hexosamines required for protein modification. Glutamine:fructose-6-phosphate amidotransferase (GFAT) is the rate-limiting enzyme controlling the synthesis of the hexosamines used in these biosynthetic pathways. We tested the idea that growth factors might activate the transcription of the GFAT gene to increase the cellular content of this rate-limiting enzyme in hexosamine synthesis. We employed a human breast cancer cell line, MDA468 cells, which express high numbers of epidermal growth factor (EGF) receptors, to determine whether EGF could stimulate transcription of the GFAT gene. Our experiments showed that EGF stimulated the accumulation of GFAT messenger RNA (mRNA) to a level 4-fold higher than that in unstimulated cells. This accumulation could be largely accounted for by an increase in transcription, as assessed by nuclear run-on experiments. Furthermore, the GFAT mRNA was highly stable and not further stabilized by EGF. This effect of EGF on GFAT gene transcription required stimulation for 12-16 h with EGF. Interestingly, when cells were exposed to 25 mM glucose instead of 5 mM glucose, this effect of EGF was blocked. Glucose had no effect on the stability of the GFAT mRNA, implying that the effect of glucose was to antagonize the transcriptional effect of EGF on the GFAT gene. Glucosamine had an effect opposite that of glucose, in that it stimulated GFAT mRNA accumulation and had an additive effect with EGF on the accumulation of this mRNA. These results demonstrate that the GFAT gene undergoes a late transcriptional response to EGF and that the provision of high glucose concentrations to the cells blocks this EGF activation. This effect of glucose does not appear to result from its metabolism through GFAT to glucosamine.

Animals↗

PubMed1994

The murine glutamine:fructose-6-phosphate amidotransferase-encoding cDNA sequence.

Glutamine:fructose-6-phosphate amidotransferase (GFAT) is the rate-limiting enzyme in hexosamine synthesis and has been implicated in the control of growth factor gene expression. We cloned a mouse cDNA which is 91% homologous to the human sequence. The deduced amino-acid sequence shows 98.6% identity to human GFAT. The cDNA is derived from a 7-kb mRNA in the mouse, while there are multiple-sized human mRNAs.

Amino Acid Sequence↗

PubMed1994

Identification and characterization of the human transforming growth factor-alpha initiator.

Eukaryotic transcription requires promoter proximal elements. For class II promoters, two such elements are the TATA box and the initiator. The promoter for the human transforming growth factor-alpha (TGF alpha) gene has been shown to lack a TATA box, yet initiate transcription at a unique site. We have identified an approximately 13-basepair sequence between -5 and +8 as a new promoter element. We call this element the TGF alpha initiator based on the following observations: 1) it is located at the transcription initiation site; 2) the promoter activity is largely reduced by either deletion or mutation of the element; and 3) mutations result in initiation upstream of the authentic start site; the TGF alpha initiator directs site-specific initiation. An electrophoretic mobility shift assay demonstrated that a protein(s) in nuclear extracts forms complexes with the TGF alpha initiator. This interaction is sequence specific and depends on nucleotides that are critical for the promoter activity in vivo. Two polypeptides, 105 and 95 kilodaltons, were detected by Southwestern blot analysis on the basis that they specifically interact with the TGF alpha initiator. The larger polypeptide, TIBP-1, was subsequently purified by a matrix-immobilized TGF alpha initiator sequence and was shown to possess the TGF alpha initiator-specific mobility shift activity and an ability to interact with the initiator when immobilized on a membrane. In summary, we identified and characterized the TGF alpha initiator, a proximal element that is important for the accurate transcription of the TGF alpha gene, and the 105-kilodalton protein that interacts with this element.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

PubMed1994

Human immunodeficiency virus 1 Tat stimulates transcription of the transforming growth factor alpha gene in an epidermal growth factor-dependent manner.

The human immunodeficiency virus 1 (HIV-1) tat gene encodes a protein of critical importance for viral transcription. In addition, Tat has been shown capable of entering cells, stimulating cell proliferation, and altering host cell gene expression. We examined the effect of Tat on the expression of the transforming growth factor alpha (TGF-alpha) gene in MDA468 human breast carcinoma cells. We showed that these cells were capable of supporting the activation of the HIV-1 long terminal repeat by Tat. Then, in cotransfection assays, in which the TGF-alpha promoter was linked to a luciferase reporter gene and the tat gene was expressed under the control of the SV40 early promoter, we showed that tat gene expression increased TGF-alpha-luciferase reporter function but only in cells stimulated with epidermal growth factor (EGF). The effects of tat and EGF were dose dependent. To confirm these cotransfection data, Tat was expressed in Escherichia coli as a fusion protein with glutathione-S-transferase (GST) and purified on glutathione-agarose. GST-Tat was introduced into the MDA468 cells either in the presence of chloroquine or by scrape loading. The biological activity of GST-Tat was tested on cells that had been stablely transfected with the HIV-1 long terminal repeat linked to luciferase as a reporter. GST-Tat was then introduced into the cells, and the level of TGF-alpha mRNA was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermal Growth Factor↗

PubMed1993

Glucose regulation of transforming growth factor-alpha expression is mediated by products of the hexosamine biosynthesis pathway.

We have recently shown that glucose and glucosamine regulate the transcription of transforming growth factor-alpha (TGF alpha) in rat aortic smooth muscle (RASM) cells. Based on the increased potency of glucosamine compared to glucose, we hypothesized that stimulation of TGF alpha transcription by glucose is mediated through the hexosamine biosynthesis pathway. The yeast cDNA for the rate-limiting enzyme of this pathway, glutamine:fructose-6-phosphate amidotransferase (GFA), was therefore expressed in RASM cells. GFA-transfected cells showed an increase in GFA activity, exhibiting a 2.2-fold increase in the synthesis of glucosamine-6-phosphate, the first product of the hexosamine biosynthetic pathway. To test the effect of GFA overexpression on TGF alpha transcriptional activity, cells were transiently cotransfected with GFA along with a reporter plasmid containing the firefly luciferase gene under control of the TGF alpha promoter. GFA-transfected cells exhibited a glucose-dependent 2-fold increase in TGF alpha activity compared to control cells. Maximal stimulation of TGF alpha-luciferase activity by glucosamine, however, was equivalent in GFA-and control-transfected cells, confirming that the stimulation observed by both agents operated through the same pathway. This increase in TGF alpha activity was inhibited (85% at 0.5 mM glucose and 69% at 30 mM glucose) by the glutamine analog and inhibitor of GFA, 6-diazo-5-oxonorleucine (10 microM). Control studies confirmed that the increased TGF alpha-luciferase activity in the GFA-expressing cells was not an artifact of altered growth, survival, or transfection efficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1993

Expression of transforming growth factor-alpha, epidermal growth factor and the epidermal growth factor receptor in adenocarcinoma of the prostate and benign prostatic hyperplasia.

The present immunohistochemical study examines the expression of TGF alpha, EGF, and the EGF receptor in prostatic tissues obtained from patients with either benign prostatic hyperplasia (BPH) or adenocarcinoma of the prostate. Frozen sections were cut at 5 microns and were incubated with monoclonal antibodies directed against TGF alpha, EGF, or the EGF receptor. The remainder of the staining procedure was performed with an avidin-biotin-complex peroxidase procedure. Strong TGF alpha expression was not detected in any of the 15 BPH specimens examined or in the normal/hyperplastic tissue intermixed within the adenocarcinomas. In contrast, malignant cells in 9 of 11 adenocarcinomas strongly expressed TGF alpha. EGF reactivity was observed in both hyperplastic and malignant epithelial tissues. EGF receptor expression was strongest along the basal aspects of cells of normal or hyperplastic glands. Although most malignant cells also were positive for the EGF receptor the level of staining was less than that observed in cells forming normal or hyperplastic glands. These results suggest that EGF and the EGF receptor may be components of an autocrine/paracrine regulatory pathway involved in hyperplastic and/or malignant disease of the prostate. The finding that TGF alpha is expressed only in malignant cells suggests that TGF alpha may represent a locally active autocrine regulator of malignant prostate cells.

Adenocarcinoma↗

PubMed1992

Glucose and glucosamine regulate growth factor gene expression in vascular smooth muscle cells.

We have investigated the regulation of the expression of two growth factors found in vascular smooth muscle, transforming growth factor alpha (TGF alpha) and basic fibroblast growth factor (bFGF). Cells cultured in medium containing 30 mM glucose exhibited a 2-fold increase in TGF alpha mRNA and a 3-fold increase in bFGF mRNA compared with cells grown in normal (5.5 mM) glucose. Glucosamine was more potent than glucose, leading to a 6-fold increase in TGF alpha mRNA. TGF alpha protein levels were also increased by glucosamine treatment, and the predominant species present was the membrane-bound precursor form of TGF alpha. To examine further the regulation of growth factors by sugars, cultured rat aortic smooth muscle cells were transfected with a plasmid construct consisting of a 1.2-kilobase-pair fragment of the TGF alpha promoter linked to a luciferase reporter gene. Increasing the concentration of glucose in the culture medium from 5.5 mM to 30 mM led to a rapid, 1.7-fold increase in the activity of the TGF alpha promoter. Glucosamine was much more potent than glucose in this stimulation, with 2 mM glucosamine causing a 12-fold increase in TGF alpha promoter activity. Insulin had no effect on luciferase activity in either the presence or the absence of added sugars. The glucose response element of the TGF alpha gene maps to a 130-base-pair segment that includes three potential binding sites for the transcription factor Sp1. We conclude that high glucose concentrations such as are reached in diabetes mellitus can stimulate the transcription of the genes for growth factors in vascular smooth muscle cells. This signaling pathway apparently involves the metabolism of glucose to glucosamine. This effect could be representative of nutritional regulation of a family of genes and could contribute to the toxicity of hyperglycemia and the vascular complications of diabetes.

Animals↗