Interaction of a common factor with ATF, Sp1, or TATAA promoter elements is required for these sequences to mediate transactivation by the adenoviral oncogene E1a

The adenovirus protein E1a stimulates transcription of both viral and cellular genes. Unlike most other transcription factors, it induces transactivation through several different promoter elements. The mechanism by which elements of diverse sequence mediate the effect of E1a is the focus of this study. Three E1a-responsive elements (an ATF site, an Sp1 site, and a TATA box containing the sequence TATAA) were studied to determine whether their interaction with a common factor is necessary for transactivation. In transfection assays, each element was used as a competitor against promoter constructs containing the other elements. The elements as competitors had no effect on basal transcription, but each competitor completely inhibited transactivation by E1a. Competitors that were not E1a responsive failed to inhibit transactivation. Therefore, either E1a itself or an E1a-inducible factor interacts with each of the elements to cause transactivation, most likely though an association with each element's specific binding protein.

Identification of a protein that interacts with the nuclear factor-1 (NF-1) binding site in cells that do not express NF-1: comparison to NF-1, cellular distribution, and effect on transcription

We examined expression of nuclear factor-1 (NF-1) in different cell lines. Expression was low or undetectable in T and B lymphocyte cell lines, whereas fibroblasts and other adherent cell lines generally had a relatively high level of NF-1 mRNA. In cell lines that did not express NF-1, gel retardation assays, nevertheless, indicated complexes between a protein or proteins and the NF-1 site. These complexes were less abundant than those formed with NF-1, they migrated more slowly, and they appeared as single species instead of the multiple species observed with NF-1. NF-1 site-binding proteins were compared in the fibrosarcoma cell line HT-1080 (expressed the highest level of NF-1 in our study) and the B cell line Raji (does not express NF-1). UV-crosslinking studies indicated that the NF-1 site-binding proteins in both cell lines were similar in size. Proteolytic clipping band shift assays suggested that the Raji protein and NF-1 share structural similarity in their DNA binding domains, but are distinct proteins. The NF-1 site mediated transcriptional stimulation in cell lines where NF-1 is expressed; however, this element did not affect transcription in cell lines that do not express NF-1, suggesting that the NF-1 site-binding protein in these cells is functionally distinct from NF-1.

The alpha 5 beta 1 fibronectin receptor. Characterization of the alpha 5 gene promoter

A genomic clone containing the gene for the alpha 5 subunit of the human alpha 5 beta 1 integrin complex was isolated by screening a human genomic library with the previously described alpha 5 cDNA (Argraves, W. S., Suzuki, S., Arai, H., Thompson, K., Pierschbacher, M. D., and Ruoslahti, E. (1987) J. Cell Biol 105, 1183-1190). The alpha 5 gene 5'-flanking region lacks both TATA and CCAAT boxes, and it is located in a CpG island. This region was an active promoter in transfection assays using the HT-1080 cell line (fibrosarcoma), which expresses alpha 5, but was inactive in the Raji cell line (B cell), which does not express alpha 5. These results indicate that the alpha 5 gene 5'-flanking region acts as a promoter that exhibits the expected cell-type specificity. Deletion of alpha 5 promoter sequences from position -657 to -178 caused transcription stimulation, suggesting that a silencer is located between these sites. Successive 5' deletions from position -178 decreased promoter activity until activity was essentially eliminated on deletion to position -27. Isolation of a functional promoter for the alpha 5 gene is a first step in understanding how expression of this gene is controlled at the molecular level.

Glycoprotein synthesis and secretion. Expression of fibronectin and its cell surface receptors

Fibronectin (FN) is an extracellular matrix protein that acts as a substrate for cell migration and adhesion during development. Cells adhere to FN through integral membrane proteins that are members of the integrin family of adhesion molecules. The interaction between cells and FN is important in a number of biologic processes, including gastrulation, hematopoietic differentiation, neural crest cell migration, cardiac development, branching morphogenesis in lung, wound healing, tumorigenesis, and metastasis. Expression of FN and its receptors is controlled by a number of hormones and growth factors as well as by tissue-specific factors. Here, the molecular aspects of how expression of these genes is controlled are reviewed, with particular emphasis on promoter regulator elements that modulate expression.

Characterization of the alpha 4 integrin gene promoter

A cDNA for the alpha 4 chain of the alpha 4 beta 1 integrin was described previously [Takada, Y., Elices, M. J., Crouse, C. & Hemler, M. E. (1989) EMBO J. 8, 1361-1368]. Primer extension analysis indicated that alpha 4 mRNA extended well beyond the 5' end of this cDNA. To clone this 5' sequence, a primer extension cDNA library was constructed, and a cDNA extending an additional 660 base pairs was isolated. This cDNA hybridized to multiple mRNAs in both T and B lymphocytes, but no alpha 4 mRNA was found in different tissues or in adherent cell lines. A single alpha 4 gene was detected in a genomic Southern blot when hybridization was done at high stringency; however, additional bands were observed at lower stringency, indicating the presence of alpha 4-related genes. Some of the different mRNAs that hybridize to the alpha 4 cDNA may then be the products of these related genes. Analysis of the alpha 4 genomic sequence revealed a large first exon of 958 base pairs. Interestingly, translation of alpha 4 initiates from the second ATG in this exon (nucleotide + 744). The first ATG (nucleotide +21) is followed by a termination codon 21 amino acids downstream. Such upstream ATG codons have been implicated in translational control of protooncogenes. One major transcriptional start site was identified by using S1 nuclease and primer extension mapping. Consensus sequences for DNA regulatory elements were found upstream of the gene and in exon 1 and intron 1. The alpha 4 gene 5' flanking region acted as a promoter in transfection assays. Detailed characterization of the promoter should provide insight into molecular events regulating expression and tissue specificity of alpha 4.

Characterization of three different elements in the 5'-flanking region of the fibronectin gene which mediate a transcriptional response to cAMP

A cAMP regulatory element (CRE) at nucleotide position -170 of the fibronectin gene was characterized previously (Dean, D. C., Blakeley, M. S., Newby, R. F., Ghazal, P., Hennighausen, L., and Bourgeois, S. (1989) Mol. Cell. Biol. 9, 1498-1506). Here we identify two additional low affinity CREs at nucleotide positions -260 and -415 which differ in sequence by 1 base pair. Interestingly, these CREs did not compete for binding of nuclear proteins in gel retardation assays and partial tryptic digestion of protein-DNA complexes produced a different pattern with each CRE, indicating that they bind different proteins. CRE (-170) competed for binding of proteins to both CREs, suggesting that it may represent a composite of the two elements. CRE (-415) competed effectively for binding of nuclear proteins to the somatostatin gene CRE, suggesting that, like the somatostatin CRE, it binds the nuclear protein CREB. On the other hand, CRE (-260) appears to bind the nuclear protein PEA-2, which also binds a site in the polyoma virus enhancer. In summary, disruption of dyad symmetry in the 3' region of the CRE, as occurs with CRE (-260) and CRE (-415), results in a lower affinity site and may also change the specificity for different nuclear proteins.

Synthesis, chemistry, and antineoplastic activity of alpha-halopyridinium salts: potential pyridone prodrugs of acylated vinylogous carbinolamine tumor inhibitors

A series of 4- and 5-[2,3-dihydro-6,7-bis[[(N-alkylcarbamoyl)oxy]methyl]-1H-pyrrol izin-5- yl]-2-halopyridinium iodides were synthesized. The rates of hydrolysis of the alpha-halopyridinium salts to the corresponding pyridones, and the reactivities of the carbamate moieties were studied as a function of pH, buffer composition, and ionic strength. The 4- and 5-pyrrolizinyl-2-halopyridinium iodides and the corresponding pyridones were evaluated against P388 lymphocytic leukemia in vivo. The alpha-fluoropyridinium compounds were active but the alpha-chloro compounds were not. This activity was correlated with the rates of hydrolysis of the alpha-halopyridinium compounds to the active pyridone. Compounds that were active in the P388 screen were evaluated in L1210 leukemia, M5076 carcinoma, and MX-1 mammary xenograft assays in mice.

Serum stimulation of fibronectin gene expression appears to result from rapid serum-induced binding of nuclear proteins to a cAMP response element

Fibronectin (FN) mRNA levels increased when quiescent cells (serum starved) were stimulated to undergo the G0/G1 transition by the addition of 20% given fetal calf serum to the media. The 5'-flanking region of the FN gene (position +69 to -510 base pairs (bp] was fused to the coding region of the chloramphenicol acetyltransferase (CAT), and the fusion gene was used in transfection assays. Expression of FNCAT increased on serum treatment indicating that the region of the FN gene between positions +69 and -510 bp mediated serum responsiveness. Deletion of FN gene 5'-flanking sequences from position -510 to -122 bp eliminated serum responsiveness suggesting that an element between these positions was mediating the effect. Sequences between positions -122 and -510 bp of the FN gene were able to confer serum responsiveness on a herpes virus thymidine kinase promoter-CAT fusion gene (TKCAT) when the FN gene sequences were cloned upstream of TKCAT. The ability to confer serum responsiveness on TKCAT was retained with a smaller 100-bp sequence (position -122 to -222 bp). Both a cAMP response element (position -170 bp) and a nuclear factor-1 binding site (position -155 bp) have been identified within this sequence (Dean, D. C., Blakeley, M. S., Newby, R. F., Ghazal, P., Hennighausen, L., and Bourgeois, S. (1989) Mol. Cell. Biol. 9, 1498-1506). The cAMP response element was serum-responsive when cloned upstream of TKCAT or a minimal FN promoter (deleted to position -56 bp) while the nuclear factor-1 binding site was unresponsive. Therefore, the cAMP regulatory element (CRE) is the serum-responsive element between position -122 and -222 bp. Serum-induced binding of proteins to the CRE was detected in gel retardation assays with extracts from cell lines where FN expression was serum-responsive. However, no serum-induced binding was detected with extracts from the JEG-3 cell line where FN expression was not serum-responsive. Serum-induced binding occurred rapidly, within 15 min, and did not require protein synthesis. The decay of serum-induced binding was relatively slow as increased binding was still detectable 24 h after removal of serum. The CRE also mediates transcriptional stimulation by cAMP, but unlike serum stimulation increased CRE binding activity was not detectable in extracts from cAMP-treated cells (Dean, D. C., Blakeley, M. S., Newby, R. F., Ghazal, P., Hennighausen, L., and Bourgeois, S. (1989) Mol. Cell. Biol. 9, 1498-1506).(ABSTRACT TRUNCATED AT 400 WORDS)

Expression of the fibronectin gene

Fibronectin (FN) is an extracellular matrix protein that acts as a substrate for cell migration and adhesion during development. FN adheres to cells through a dimeric membrane protein, the FN receptor. Antibodies to FN and synthetic peptides that inhibit FN-receptor interaction inhibit gastrulation, block neural crest cell migration, arrest cardiac development, and block the fusion of myoblasts to form myotubes. FN and its receptor also appear to be important for lung development, where their expression coincides with the onset of branching morphogenesis, but drops to barely detectable levels in adult lung, indicating developmental specificity. FN expression is generally low in most adult tissues. However, synthesis is drastically increased during injury and wound healing, a process that in many ways mimics development. FN synthesis is also drastically increased in fibroproliferative lung lesions associated with major architectural changes in the lung. Expression of FN is regulated by a variety of growth factors and hormones. Several of these inducers (cAMP, transforming growth factor-beta, epidermal growth factor, platelet-derived growth factor, glucocorticoids, and vitamin D3) have themselves been implicated in developmental processes, and both cAMP and transforming growth factor-beta are known to stimulate expression of other matrix genes. One role of these hormones and growth factors in development may be to control expression of matrix genes, thereby controlling cell migration and adhesion. In the following report, the effect of hormones and growth factors on expression of the FN gene is reviewed.

Forskolin inducibility and tissue-specific expression of the fibronectin promoter

The mechanism of cyclic AMP (cAMP) induction of fibronectin (FN) in HT-1080 and JEG-3 cells differs (D. C. Dean, R. F. Newby, and S. Bourgeois, J. Cell Biol. 106:2159-2170, 1988). In the fibrosarcoma cell line HT-1080, induction requires both protein synthesis and a lag period of 12 to 24 h. In the choriocarcinoma cell line JEG-3, protein synthesis is not required and induction peaks before 24 h, declining thereafter. We show that the FN promoter is transcribed in vitro and that the transcripts initiate at the proper site. Based on transfection experiments with these cells and FN promoter constructions, a cAMP-responsive element (CRE) was identified between -157 and -188 base pairs upstream of the human FN gene. This sequence also conferred cAMP inducibility in both cell lines on the herpesvirus thymidine kinase promoter when it was placed upstream of a thymidine kinase-chloramphenicol acetyltransferase fusion gene. DNase I protection analysis and gel retardation experiments revealed that the CRE was bound by a protein(s) that was present in both HT-1080 and JEG-3 cells as well as in NIH 3T3 cells. Multiple protein-CRE complexes were resolved by gel retardation with extracts of both cell lines. Forskolin treatment of these cells did not alter qualitatively or quantitatively the pattern of CRE-binding proteins that was observed. The FN promoter was at least 10 times more active in HT-1080 than in JEG-3 cells, even though in JEG-3 cells both the rate of FN biosynthesis and the level of accumulated FN mRNA were greater than those in HT-1080 cells. The difference in promoter activity in HT-1080 and JEG-3 cell was mediated by sequences that were located between positions -510 and -56. Deletion of the FN promoter from positions -510 to -56 resulted in an ~30-fold decrease in promoter activity when this construction was transfected into HT-1080 cells, and similar results were observed in NIH 3T3 cells; however, less than a 2-fold effect was observed in JEG-3 cells. Results of these studies suggest that there is some degree of tissue specificity of FN gene expression and reveal that cAMP induction is mediated, in part, by the same element (CRE) in both HT-1080 and JEG-3 cells.

Regulation of fibronectin biosynthesis by dexamethasone, transforming growth factor beta, and cAMP in human cell lines

The regulation of fibronectin (FN) biosynthesis by dexamethasone (a synthetic glucocorticoid), forskolin (an activator of adenylate cyclase), and transforming growth factor beta (TGF-beta) was examined in six human cell lines. Dexamethasone treatment produced the largest increase in FN biosynthesis in the fibrosarcoma cell line, HT-1080 (approximately 45-fold). This seems to result from a dexamethasone-mediated increase in FN mRNA stability which increases the message half-life from approximately 11 to 26 h. The relative instability of FN mRNA in the fibrosarcoma (t1/2 11 h) compared to normal fibroblasts (70 h) appears to result from the particular transformed phenotype of the HT-1080 cells. Forskolin and TGF-beta increase the rate of FN gene transcription in most of the cell lines. These effects (four- to six-fold) occur rapidly and do not require protein synthesis in the responsive cell lines which include normal fibroblasts. However, in the fibrosarcoma (HT-1080), a surprisingly large induction (20-30-fold) is observed and this induction is different from that in the normal fibroblasts and the other cell lines in that both protein synthesis and a lag period are required. Synergism is seen with dexamethasone and either forskolin or TGF-beta in HT-1080 cells increasing the rate of FN biosynthesis approximately 200-fold to a level similar to normal fibroblasts. This seems to result from a combination of FN mRNA stabilization (dexamethasone) and increased transcription (forskolin and TGF-beta).

Cloning and analysis of the promotor region of the human fibronectin gene

Human fibronectin (FN) genomic clones were isolated by screening a human genomic library with a 75-base oligonucleotide. The sequence of the oligonucleotide corresponds to a region near the 5' end of the human FN cDNA clone pFH6 that contains the amino-terminal coding sequences but does not extend to the 5' end of the mRNA [Kornblihtt, A. R., Umezawa, K., Vibe-Pedersen, K. & Baralle, F. E. (1985) EMBO J. 4, 1755-1759]. The 5' end of the FN gene is found on a 3.7-kilobase-pair EcoRI fragment that contains about 2.7 kilobase pairs of flanking sequence. The first exon is 414 base pairs long, with a 5' untranslated region of 267 base pairs. As deduced on the basis of the position of the initiation codon, FN is synthesized with a 31-residue amino acid extension on the amino terminus that is not present in the mature polypeptide. This amino-terminal extension appears to contain both a signal peptide and a propeptide. The first 200 base pairs of 5'-flanking sequence is very G + C rich. Upstream of this the sequence becomes relatively A + T rich. The sequence ATATAA is found at -25 and the sequence CAAT is present at -150. The sequence GGGGCGGGGC at -102 exhibits homology to the binding site for the transcription factor SP1, and the sequence TGACGTCA at -173 exhibits homology to 5'-flanking sequences important for induction by cAMP.

Intestinal basement membrane of Ascaris suum. Molecular organization and properties of the collagen molecules

The collagenous components of Ascaris suum intestinal basement membrane were isolated by extraction with 0.1 M Tris-HC1, 0.5 M NaC1, 0.5% 2-mercaptoethanol, pH 8.3, and Sephacryl S-300 gel filtration. Rotary-shadowing electron microscopy showed that the collagenous components occur as monomers and dimers with mean contour lengths of 469 +/- 21 and 918 +/- 24 nm, respectively. The molecules each contain a globular domain, with that of the dimer being slightly larger than that of the monomer. Electrophoresis in sodium dodecyl sulfate-polyacrylamide gels under reducing conditions revealed two polypeptides of Mr = 185,000 and 179,000. A similarity to type IV collagen was indicated by a glycine content of less than 33 mol % and the presence of fucose, mannose, and glucosamine residues. Treatment of the collagen with pepsin resulted in loss of the globular domains but retention of 90% of the length of fibrous collagen segments. Collagenase, however, removed the fibrous regions but left the globular moieties intact. These results extend the previously proposed model (Hung, C.-H., Noelken, M. E., and Hudson, B. G. (1981) J. Biol. Chem. 256, 3822-3826) in which the collagenous domain consists of two monomer-sized triple-helical subunits joined end-to-end by disulfide bonds, with the constituent chains of each subunit being cross-linked by disulfide bonds.

A similar 5'-flanking region is required for estrogen and progesterone induction of ovalbumin gene expression

We have previously transferred an ovalbumin-beta-globin fusion gene (ovalglobin) into primary cultures of chick oviduct cells and demonstrated that an ovalbumin gene 5'-flanking sequence between -221 and -95 is necessary for progesterone-mediated transcriptional induction (Dean, D. C., Knoll, B. J., Riser, M. E., and O'Malley, B. W. (1983) Nature (Lond.) 305, 551-554). Here we compare 5'-flanking sequences required for induction of the ovalglobin gene by 17 beta-estradiol and progesterone. The early gene of simian virus 40 was inserted into the same plasmid as the ovalbumin fusion gene to serve as an internal control. Since transcription of the viral early gene was unaffected by the presence of steroid hormone or deletions in the ovalbumin gene 5'-flanking region, the level of its transcripts could be monitored as a reference standard for ovalglobin transcription. Ovalglobin transcripts initiated principally from the ovalbumin cap site in the presence or absence of progesterone and 17 beta-estradiol. Deletion of 5'-flanking sequences to -197 had little effect on the induction with either hormone, while successive deletions to -180, -161, and -143 resulted in a gradual decrease in the level of induction. Deletion to -95 eliminated the induction. The results of this study indicate that DNA control elements for regulation of the ovalbumin gene by estrogen and progesterone either overlap directly or are clustered in close proximity in the 5'-flanking region near the ovalbumin gene promoter.

Effect of left ventricular aneurysmectomy on exercise performance

We performed pre- and post-operative exercise testing on 12 patients with coronary artery bypass surgery and ventricular aneurysmectomy and 2 patients with ventricular aneurysmectomy alone. Most patients showed better exercise performance, higher double product, better work capacity and were able to exercise longer. Two patients who had ventricular aneurysmectomy alone showed similar changes. Most patients showed improved New York Heart Association functional classification and exercise performance after surgery.

Definition of the ovalbumin gene promoter by transfer of an ovalglobin fusion gene into cultured cells

In order to study the initiation of transcription from the ovalbumin gene promoter, we constructed a hybrid gene (ovalglobin) in which 753 bps of ovalbumin gene 5'-flanking sequence were joined to the chicken adult beta-globin gene. When transfected into HeLa S3 cells, ovalglobin gene transcription initiated at the ovalbumin gene cap site, as measured by S1 nuclease and primer extension analysis. Deletion of 5'-flanking sequences to position -95 had little effect on transcription; deletion to -77 reduced transcription to about 20% of the wild type level and deletion to -48 reduced the level to about 2%. A deletion to -24, removing the sequence TATATAT, abolished transcription entirely. Hormonal regulation of the ovalglobin gene was observed when primary oviduct cells were used as recipients for DNA transfection. Under these conditions, addition of progesterone increased the level of ovalglobin transcripts to more than 10 times the uninduced level.

A 5'-flanking sequence essential for progesterone regulation of an ovalbumin fusion gene

Ovalbumin gene transcripts are not detectable in unstimulated chick oviducts but comprise about half of oviduct cell transcripts after steroid hormone induction. This seems to result mostly from an increased level of transcription. When steroid hormones enter the cytoplasm of target cells they bind to specific receptors and the steroid-receptor complex accumulates in the nucleus. Presumably this complex then binds in a sequence- or conformation-specific way near the regulated gene and enhances transcription. Several recent studies have shown that steroid hormone receptors bind preferentially to the 5'-flanking region of steroid-responsive genes in vitro. Transcription of cloned genes for alpha 2u globulin, growth hormone, mouse mammary tumour virus and lysozyme can be induced in vivo by steroid hormones after transfer to cells containing steroid hormone receptors. In some of these studies, 5'-flanking regions were shown to be important for steroid regulation. We have now constructed a hybrid gene containing the ovalbumin gene promoter fused to the chicken adult beta-globin gene and transferred it into primary cultures of chicken oviduct cells. We show that progesterone-mediated induction of transcription in untransformed oviduct cells depends on an ovalbumin gene flanking sequence between positions -95 and -222.

Improved exercise performance following single daily dose of atenolol in stable angina

We administered atenolol to 10 patients with effort limiting angina pectoris. Doses of 50 mg, 100 mg and 200 mg provided significant improvement (P less than 0.05) in exercise tolerance tested 24 hours after the drug was given. Twenty-five milligrams was not significantly better than placebo in increasing work tolerance. Side effects were minimal, and treatment could be continued throughout the study. The beta-blocker atenolol is an effective drug in the treatment of exercise-induced angina.

Immunohistochemistry of types I and II collagen in undecalcified skeletal tissues

Types I and II collagen were demonstrated in semithin sections of undecalcified human endochondral growth plate, articular cartilage, and subchondral bone. The effects of several different methods for fixation, embedding, exposing of antigenic determinants, and immunoperoxidase staining were examined. Fixation in buffered formalin and paraformaldehyde-lysine-periodate solution gave more intense staining for collagens than fixation in paraformaldehyde-gluaraldehyde or Bouin's solution. Specimens embedded in Spurr epoxy resin yielded intense and uniform staining of areas known to contain the particular collagens after the resin had been removed by sodium ethoxide. The staining was enchanced following enzymatic digestion, especially with protease V (Sigma). Staining sensitivity and specificity were comparable with the indirect conjugate and double peroxidase-antiperoxidase (PAP) techniques; the PAP method was less sensitive. Embedment in methacrylate resins proved unsatisfactory because of exaggerated immunostaining of mineralized sites in comparison to unmineralized areas of the same tissues. In the growth plate specimens, type I collagen was identified in the matrices of bone, periosteum, perichondrium, and in the cytoplasm of hypertrophic and degenerative chondrocytes. Type II collagen was found uniformly throughout the cartilage matrix and in spicules of unresorbed cartilage matrix located in subchondral bone. A similar staining pattern was observed for the articular cartilage, except that type I collagen was not detected in chondrocytes.

Isolation of type IV procollagen-like polypeptides from glomerular basement membrane. Characterization of pro-alpha 1(IV)

Type IV procollagen-like constituents of glomerular basement membrane were solubilized by reduction and alkylation of disulfide bonds under denaturing conditions. Four polypeptides were observed with apparent Mr = 185,000, 175,000, 164,000, and 152,000. The two largest chains correspond to pro-alpha 1(IV) and pro-alpha 2(IV), described in model systems which secrete a basement membrane-like matrix, while the smaller chains appear to be shortened forms of these polypeptides. Fractionation of the four polypeptides into two groups was achieved by ion exchange chromatography. Pro-alpha 1(IV) and 164,000 polypeptide are relatively acidic with respect to pro-alpha 2(IV) and 152,000 polypeptide, which is due in part to a relatively high content of arginine in the latter. Based on amino acid analysis of the collagenase-sensitive regions of these polypeptides, pro-alpha 1(IV) is the parent molecule from which alpha 1(IV) is derived on pepsin digestion of basement membranes and pro-alpha 2(IV) is the parent molecule of alpha 2(IV). Pro-alpha 1(IV) was isolated by gel filtration and ion exchange chromatography and characterized. It has a molecular weight of 194,000 as determined by sedimentation equilibrium. The polypeptide contains 14% carbohydrate in the form of both disaccharide, glucosylgalactosylhydroxylysine, and heteropolysaccharide units. The polypeptide backbone mass is calculated to be 167,000 daltons. Digestion of pro-alpha 1(IV) with bacterial collagenase resulted in two resistant segments of mass = 31,000 and 33,000 dalton, which make up approximately 30% of the polypeptide.

Mitral regurgitation in coronary artery disease

Over a period of 5.25 years, 1,530 patients with coronary artery disease (CAD) underwent catheterization; 104 had associated mitral regurgitation (MR), and 60 had no complications. Twelve patients underwent coronary artery bypass graft surgery (CABG), with both pre- and postoperative angiograms. Nine of the 12 patients (75 percent) were in functional class 3 or 4. Left ventricular ejection fraction ranged from 34 to 75. The MR was considered severe (3+) in three, moderate (2+) in six, and trivial (1+) in three patients. Following CABG, all except two patients were in class 1. Of the 43 patients medically treated, 31 patients (72 percent) were in functional class 3 or 4. Angiographic results showed that five patients had 3+ MR, 14 had 2+ MR, and 24 had 1+ MR. The EF was less than 30 in 23 patients and greater than or equal to 30 in 20 patients, and left ventricular filling pressure was elevated. Twenty patients died, with a mean follow-up period of 11 months. Our study demonstrates that the surgically treated patients showed angiographic improvement in MR, improved functional status, and relief of symptoms compared with medically treated patients. We believe that a subset of patients with MR and CAD would benefit with CABG.

Bovine glomerular basement membrane. Characterization of an alpha-size collagenous polypeptide

The collagenase domain of bovine glomerular basement membrane was isolated in soluble form after limited digestion with pepsin. Gel filtration chromatography of the domain under denaturing conditions revealed that most of the polypeptide constituents exhibit apparent molecular weights greater than the type I collagen beta-chain, while approximately 15% are similar in size to that of alpha-chain. Carboxymethyl cellulose chromatography of the alpha-size region revealed that 70% of the protein was polypeptide XIV, as previously designated (West, T. W., Fox, J. W., Jodlowski, M., Freytag, J. W., and Hudson, B. G. (1980) J. Biol. Chem. 255, 10451-10459). This polypeptide exhibits an apparent molecular weight of 102,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. An absolute molecular weight value of 86,000 was determined by sedimentation equilibrium ultracentrifugation in 6 M guanidine hydrochloride. About 15% of the mass is carbohydrate which exists in the form of glucosylgalactosylhydroxylysine. Thus, the polypeptide backbone has a molecular weight of 73,000, a value which is considerably smaller than the alpha-chains of classical collagen. The amino acid and carbohydrate composition and cyanogen bromide patterns indicate that polypeptide XIV has a structure similar to that of C-chain or alpha 1 (IV) collagen which has been identified in other tissues. In addition, the cyanogen bromide pattern of the entire collagenous domain is similar to that of polypeptide XIV, suggesting that the latter is a structural segment of many of the higher molecular weight components.