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B F Tack

Publications and source records attributed to B F Tack.

At least 19 recordsLinked to original sources
PubMed1992

Regulation of C4b-binding protein gene expression by the acute-phase mediators tumor necrosis factor-alpha, interleukin-6, and interleukin-1.

C4b-binding protein (C4BP) is involved in the fluid-phase regulation of the classical pathway of complement. During an acute-phase response, we have shown that hepatic levels of murine C4BP mRNA are elevated 2.5-fold while rat liver C4BP gene expression exhibits a 4-fold induction. Furthermore, a survey of different mouse tissues showed that during acute inflammation C4BP gene expression was confined to the liver. To gain a better understanding of the acute-phase regulation of C4BP gene expression we utilized the rat hepatoma cell line FAO in which tumor necrosis factor-alpha (TNF-alpha) produced a 2.7-fold induction of C4BP mRNA levels. In the absence of TNF-alpha, interleukin-1 alpha (IL-1 alpha) and interleukin-6 (IL-6) had little effect on C4BP gene expression but when all three cytokines were used together a synergistic 4-fold induction of C4BP mRNA levels was observed. In contrast the synthetic glucocorticoid dexamethasone inhibited TNF-alpha-induced C4BP gene expression. Cycloheximide-mediated inhibition of inducible C4BP gene expression demonstrated the requirement for ongoing protein synthesis. Rapid induction of C4BP mRNA levels by TNF-alpha and IL-6 (within 1 h) and the observation that stimulation was inhibited by actinomycin D provided evidence that regulation of C4BP gene expression during the acute-phase response is regulated at the transcriptional level. Isolation of a genomic clone extending into the 5' regulatory region of the rat C4BP gene enabled us to identify the major transcriptional start site and putative response elements through which TNF-alpha, IL-6, IL-1 alpha, and dexamethasone may exert their effects on C4BP gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute-Phase Reaction↗
PubMed1992

Complete structure of the murine C4b-binding protein gene and regulation of its expression by dexamethasone.

C4b-binding protein (C4BP) is involved in the fluid-phase regulation of the classical pathway of complement. A murine genomic library was screened, and five clones were selected that covered the remaining four exons in the 5'-region of the C4BP gene. Together with previous work (Barnum, S. R., Kristensen, T., Chaplin, D. D., Seldin, M. F., and Tack, B. F. (1989) Biochemistry 28, 8312-8317), the entire C4BP gene has now been shown to be 23 kilobases (kb) long and comprised of 10 exons ranging in size from 86 to 442 base pairs (bp). Primer extension analysis revealed the major transcription start site to be 46 bp upstream of the published cDNA start site. Northern blot analysis of RNA isolated from several mouse tissues demonstrated that the C4BP gene is expressed in a liver-specific manner. Several regions homologous to known response elements were identified upstream of the C4BP gene including a strong hepatocyte nuclear factor 1 binding site and four putative glucocorticoid response elements. Furthermore, dexamethasone increased C4BP mRNA and protein levels in the mouse liver cell line, NMuLi. The stimulation of C4BP gene expression was rapid and independent of protein synthesis. These results suggest dexamethasone induction of the C4BP gene is a primary response and therefore a transcriptional effect. Inhibition of the dexamethasone effect on C4BP by actinomycin D supports this theory. These studies also provide evidence that, for optimal induction of the C4BP gene, the glucocorticoid receptor complex may cooperatively interact with accessory transcription factors. It is likely that stimulation of C4BP gene expression by dexamethasone may allude to a mechanism by which glucocorticoids exert their anti-inflammatory effects.

Animals↗
PubMed1991

Structural aspects of the human C5 gene. Intron/exon organization, 5'-flanking region features, and characterization of two truncated cDNA clones.

Human C5 cDNA fragments were used to identify five overlapping cosmid clones that spanned the entire C5 gene. Partial sequencing and Southern analysis of the clones were performed to identify intron/exon boundaries and to map intron size. The human C5 gene is 79 kilobases in length and is comprised of 41 exons. Comparison of C5 with the homologous family members C3 and C4 revealed striking similarities in exon size and number. Less, although significant similarities were also observed with the family member alpha 2-macroglobulin. The transcriptional start site for the C5 gene was observed as a doublet at positions 29 and 28 nucleotides upstream of the ATG start codon. The 5'-flanking region of the gene contains sequences homologous with several known responsive elements, including interferon, interleukin-6, glucocorticoid, estrogen, NF-kappa B, and HNF-1. Two previously identified truncated cDNAs, pHC5A and pHC5B, contain 21 and 16 exons, respectively. The last exon in pHC5A, designated exon 21a, is a product of alternative splicing and is not present in the major full-length transcript. Truncation of pHC5A is the result of an alternative polyadenylation signal located in exon 21a. In pHC5B, exon 16 is extended on the 3' end by additional flanking genomic sequence that also contains an alternative polyadenylation signal.

Animals↗
PubMed1991

Structural features of the human C3 gene: intron/exon organization, transcriptional start site, and promoter region sequence.

The third component of human complement (C3) is a key molecule in the activation of the complement cascade. C3 cDNA fragments were used to identify seven cosmid clones that covered all but 1 kilobase pair (kb) of the C3 gene. The remainder of the gene was cloned by using the polymerase chain reaction. These clones were used to identify the intron/exon boundaries and to map the gene. The C3 gene is 42 kb in length and comprises 41 exons ranging in size from 52 to 213 base pairs (bp). The transcription start site was identified by primer extension, and approximately 1 kb of DNA upstream of this site was sequenced. Putative TATA and CAAT boxes were identified along with a number of regions that shared homology with known regulatory sequences. These include responsive elements for interferon-gamma, interleukin-6, nuclear factor kappa B, estrogen, glucocorticoids and thyroid hormone. Several of these agents have been shown to affect C3 synthesis and mRNA levels. The sizes of the exons in C3 were compared to those of C4 and alpha 2-macroglobulin (alpha 2M). Thirty-nine of 41 exons in C4 were found to be of similar size to the analogous ones in C3, and two-thirds of those in alpha 2M were also similarly sized, supporting the hypothesis that these genes arose from a common ancestor.

Amino Acid Sequence↗
PubMed1990

Mapping of a retinoic acid-responsive element in the promoter region of the complement factor H gene.

Retinoic acid receptors are members of the steroid/thyroid hormone receptor superfamily. Pursuant to the discovery that dexamethasone increases complement factor H expression, we examined the effects of retinoic acid on this gene. Both H mRNA and protein levels are increased by retinoic acid in L cells. Using the luciferase reporter gene system we have identified a region of the H promoter required for the retinoic acid response. This region contains an imperfect palindrome of the TGACC motif, present in thyroid hormone and estrogen-responsive elements. We demonstrate specific binding of the retinoic acid receptor beta to this sequence of the H gene by DNA-protein gel retardation assay. Therefore, these studies extend the sphere of influence of the retinoids to complement, an intrinsic component of the humoral immune system.

Animals↗
PubMed1990

Identification and sequence analysis of four complement factor H-related transcripts in mouse liver.

Mouse liver RNA analyzed by Northern blotting with a full-length complement factor H cDNA probe demonstrates the 4.4-kilobase (kb) H mRNA as well as three additional hybridizing species of 3.5, 2.8, and 1.8 kb, respectively. Further characterization of these alternative transcripts was pursued by isolation of additional cDNAs from a liver library using a full-length H probe. Twelve clones homologous to but distinct from H were isolated, analyzed by restriction mapping, and divided into four classes, A, B, C, and D, based on their sequences. Clones from classes A, B, and C all contained nearly identical 5'-untranslated regions and leader sequences that differed from H at more than 50% of their nucleotide positions. The 5'-untranslated and leader sequences of the class D clone were unrelated to the corresponding regions of H or the class A, B, or C clones. The remaining portions of the H-related cDNAs were made up of short consensus repeats, 7 in class A, 4 in class B, 13 in class C, and 5 in class D. To determine the relationship between the H-related transcripts and the cDNA clones, Northern blots of liver RNA were analyzed by hybridization with two probes, one specific for the class D cDNA and the other reacting specifically with the class A, B, and C cDNAs. The class A/B/C probe detected transcripts of 3.5, 2.8, and 1.8 kb in liver RNA, and the class D probe hybridized to a distinct 1.8-kb message. Additionally, a cosmid genomic library was screened with H cDNA, and nine H-related clones were isolated. They spanned a region of approximately 120 kb, defining at least two discrete H-related gene loci. These results identify new members of the super-family of C3b/C4b binding protein genes.

Amino Acid Sequence↗
PubMed1990

Structure and chromosome assignment of the murine p36 (calpactin I heavy chain) gene.

p36 is a major substrate of both viral and growth factor receptor associated protein kinases. This protein has recently been named calpactin I heavy chain since it is the large subunit of a Ca2(+)-dependent phospholipid and actin binding heterotetramer. The primary structure of p36 has been determined from analysis of cloned cDNA. The protein contains 338 amino acids, has an approximate molecular weight of 39,000, and is comprised of several distinct domains, including four 75 amino acid repeats. From two overlapping cosmid clones isolated from different mouse genomic liver libraries, the complete intron/exon structure of the p36 gene was determined and the 5' and 3' noncoding regions of the gene were analyzed. The coding and 3' untranslated region of the p36 gene contains 12 exons which range in size from 48 to 322 base pairs (bp) with an average size of 107 bp. The repeat structures found at the protein level are not delineated by single exons, but the N-terminal p11-binding domain is encoded by a single exon. Structural mapping of the gene demonstrated that the lengths of the first two introns in the coding region are together approximately 6 kilobases (kb), while the other introns range in size from 600 to 3600 bp with an average size of 1650 bp. The p36 gene is at least 22 kb in length and has a coding sequence of approximately 1 kb, representing only 4.5% of the gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

Factor H.

While the mouse and human H proteins are structurally and functionally similar, they differ in their genetics. Whereas there is no evidence in humans for more than one gene; in mice the H locus is complex. Based on cDNA sequence and hybridization analysis of genomic cosmid clones, there are at least three distinct genes, all highly related to one another. The consensus repeating unit that comprises this molecule has obviously been duplicated numerous times, since it is present in many other molecules. Thus, it is not surprising to discover that there are several genes related to H in the mouse. A similar case has been described for two other members of this family. In humans, CR1 cDNA hybridizes to two distinct genomic clusters in the CR1 locus (Wong et al. 1989), and in mice, mCRY hybridizes to two regions in the genome, one on chromosome 1 and another on chromosome 8 (Aegerter-Shaw et al. 1987). It will be of interest to see if any other members of this family display as complex a genetic locus as murine H.

Animals↗
PubMed1989

Analysis of complement factor H mRNA expression: dexamethasone and IFN-gamma increase the level of H in L cells.

Murine complement protein H is encoded by a 100-kb gene on chromosome 1. A 3.2-kb fragment of the 5' flanking region of the H gene was sequenced, and two transcription start sites for this gene were identified by RNase protection and S1 nuclease analyses, each of which had upstream TATA and CAAT boxes. This region shares sequence homology with known regulatory elements, including the SV40 enhancer consensus, the Sp1 binding site, and two glucocorticoid-responsive core elements (GRE). Tissue and cell-line specificity has been examined by Northern analysis, and the 4.4-kb full-length H messenger RNA was identified in liver, kidney, spleen, thymus, liver cell line 1469, and L cells. IFN-gamma did not induce H mRNA expression in the macrophage cell line P388D.1 but had a positive effect on both the mRNA and protein levels of H in L cells. PMA, LPS, and vitamin D did not increase H mRNA levels in L cells. Pursuant to the discovery of two GRE in the 5' regulatory region of the H gene, we examined the effects of glucocorticoids on H mRNA expression. Dexamethasone (10(-7) M) was found to increase markedly the levels of H mRNA and protein after 24 h of incubation, and the effect on the mRNA was detectable by 30 min. The fact that H is a down-regulator of complement activation is consistent with the known immunosuppressive role of glucocorticoids. To our knowledge, this is the first time that dexamethasone has been shown to increase the levels of a complement protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Molecular analysis of the murine C4b-binding protein gene. Chromosome assignment and partial gene organization.

Murine C4b-binding protein (C4BP) is a regulatory molecule in the classical pathway of complement. C4BP is composed predominantly of short consensus repeats (SCRs) approximately 60 amino acids in length, which contain a framework of conserved residues. The SCRs are found in many complement molecules and a growing number of noncomplement molecules as well and are a major structural feature of some of these molecules. To characterize the structure of the murine C4BP gene, a cosmid library constructed from Balb/c liver DNA was screened. Several nearly identical, overlapping clones were identified; however, none of the clones, alone or in combination, covered the entire C4BP gene. One clone (D26) was chosen for detailed analysis and found to contain all but the leader region, the first SCR, and the first half of the second SCR. The SCRs three through six were each encoded by single exons. Only the latter half of the second SCR was present on the clone, and it was encoded by a single exon, demonstrating that murine C4BP has a split SCR at the genomic level. Structural mapping of this portion of the gene demonstrates that the region extending from the second half of the second SCR through the nonrepeat and untranslated region spans approximately 12 kb; however, genomic Southern blot analysis suggests that the gene is between 20 and 30 kb in length. Analysis of the 3' genomic sequence demonstrates that this region of the gene has homology with SV-40 late (class II) RNA sequences. These sequences may play a role in 3' cleavage of the precursor RNA prior to polyadenylation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1989

Complete intron/exon organization of DNA encoding the alpha' chain of human C3.

The third component of human complement (C3), a central molecule in both the classical and alternative pathways of complement, is comprised of two polypeptides, termed the alpha and beta chains. Activation of C3 cleaves the alpha chain into two fragments, C3a, an inflammatory peptide, and the alpha' chain which remains covalently linked to the beta chain. Proteolytic fragments derived from the alpha' chain during activation and regulation of complement play a significant role in host defense and regulation of the immune response. Two cosmid clones covering the alpha' chain region were used to characterize the structure of this portion of the C3 gene. The alpha' chain is encoded by 24 exons, which range in size from 52 to 213 base pairs (bp) with an average size of 115 bp. The splice donor sequence at the beginning of intron 12 has a rare sequence variant of GC instead of the usual GT sequence. Ten introns have been completely sequenced and were surprisingly short, ranging in size from 85 to 242 bp with an average of 140 bp. Other introns range in size from 250 bp to over 4 kilobases in length. The gene size for this portion of C3 is estimated to be 23-24 kilobases. Comparison of exon structure with protein domains and with peptide mapping studies demonstrates that several binding sites on C3 are encoded by single exons. These data support the hypothesis that individual exons can code for functional protein domains.

Base Sequence↗
PubMed1989

Genetic organization of complement receptor-related genes in the mouse.

Using an interspecific cross, gene linkage relationships among members of the murine complement receptor-related genes, C4bp, Cfh, Mcry, and Mcr2, were analyzed by segregation of RFLP in 200 mice. The human homologues of these genes are tightly linked, composing the RCA locus, which maps to human chromosome (Chr.)1q32, within a large linkage group conserved between human Chr.1q21-32 and mouse Chr.1. RFLP associated with C4bp and Cfh map within this conserved linkage group; Cfh is located 9 cM telomeric to C4bp, which is consistent with linkage data for their human homologues. Mcry and Mcr2, while tightly linked, are located outside the conserved group, 40 cM telomeric to C4bp. These data suggest that a translocation or inversion occurred within the RCA family during the evolution of the mouse, defining a breakpoint of this large conserved linkage group.

Animals↗
PubMed1988

Structure of the murine complement factor H gene.

Factor H is a regulatory protein of the alternative pathway of complement activation comprised of 20 tandem repeating units of 60 amino acids each. A factor H cDNA clone was used to identify 17 genomic clones from a cosmid library. Four clones were selected for analysis of intron/exon junctions and 5' and 3' regions of the gene and for mapping of the exons. The factor H gene was found to be comprised of 22 exons. Each repeating unit is encoded by one exon, except the second repeat, which is coded by two exons; the leader sequence is encoded by a separate exon. The exons range in size from 77 to 210 base pairs (bp) and average 178 bp. They span a region of approximately 100 kilobases (kb) on chromosome 1. The leader sequence exon is 26 kb upstream of the first repeat exon, representing the largest intron. The other introns range in size from 86 bp to 12.9 kb, and the average intron size is 4.7 kb. Analysis of the genomic organization of the factor H gene has provided insight into the protein structure and will enable the construction of deletion mutants for functional studies.

Animals↗
PubMed1987

cDNA sequence and tissue distribution of the mRNA for bovine and murine p11, the S100-related light chain of the protein-tyrosine kinase substrate p36 (calpactin I).

We have isolated and sequenced cDNA clones of bovine and murine p11 mRNAs. The nonpolyadenylated mRNAs are predicted to be 614 and 600 nucleotides, respectively. The p11 mRNAs both contain a 291 nucleotide open reading frame, preceded by a 5'-untranslated region of 73 nucleotides in bovine p11 mRNA and of 68 nucleotides in murine p11 mRNA. The deduced bovine p11 amino acid sequence is identical to the previously published partial bovine and complete porcine p11 protein sequence except for an additional COOH-terminal lysine residue. The bovine and murine p11 proteins are 92% homologous, whereas at the nucleotide level the conservation is 89% in the coding region and 75% in the 3'-untranslated region. Southern analysis of murine genomic DNA detected a single p11 gene, less than 10 kilobase pairs in size, containing as many as three introns. The p11 gene has been assigned to mouse chromosome 3 by analysis of interspecific hybrid cell panels and recombinant inbred mouse strains. The p11 gene is closely linked to the Xmmv-65 endogenous leukemia virus env gene and the guanylate binding protein-1 gene. Northern analyses of RNAs from mouse tissues and cell lines indicated that p11 mRNA levels vary widely. They are very low in liver, heart, and testes, moderate in brain, spleen, and thymus, and high in kidney, intestine, and lung. Analysis of the same RNA samples for p36 mRNA levels showed that expression of p11 and p36 mRNAs is not always coordinated. Brain and the mouse embryonal carcinoma cell line F9 contain moderate to high levels of p11 mRNA with very low levels of p36 mRNA. Sequence homology between p11 and the S100 proteins, and the serum-induced 2A9 gene product, as well as possible functions of p11 are discussed.

Amino Acid Sequence↗
PubMed1987

The superfamily of C3b/C4b-binding proteins.

The determination of primary structures by amino acid and nucleotide sequencing for the C3b-and/or C4b-binding proteins H, C4BP, CR1, B, and C2 has revealed the presence of a common structural element. This element is approximately 60 amino acids long and is repeated in a tandem fashion, commencing at the amino-terminal end of each molecule. Two other complement components, C1r and C1s, have two of these repeating units in the carboxy-terminal region of their noncatalytic A chains. Three noncomplement proteins, beta 2-glycoprotein I (beta 2I), the interleukin 2 receptor (IL 2 receptor), and the b chain of factor XIII, have 4, 2 and 10 of these repeating units, respectively. These proteins obviously belong to the above family, although there is no evidence that they interact with C3b and/or C4b. Human haptoglobin and rat leukocyte common antigen also contain two and three repeating units, respectively, which have more limited homology with the repetitive regions in this family. All available data indicate that multiple gene duplications and exon shuffling have been important features in the divergence of this family of proteins with the 60-amino-acid repeat.

Amino Acid Sequence↗
PubMed1987

Primary structure of the fifth component of murine complement.

A cDNA library was constructed by the method of Okayama and Berg, [Okayama, H., & Berg, P. (1983) Mol. Cell. Biol. 3, 280-289] employing size-selected (greater than 28 S) poly(A+) liver RNA from the mouse strain B10.WR. A total of 150,000 recombinants were screened with a partial human C5 cDNA probe; 16 C5-positive clones were identified, 1 of which contained an insert greater than 5.2 kilobase pairs in length. This cDNA insert was fully sequenced by the dideoxy method. The DNA sequence of this insert had an open reading frame of 4920 base pairs specifying a sequence of 1640 amino acid residues. The region corresponding to positions 372-812 exhibited high homology with the previously determined partial structure for human C5 of 438 amino acid residues. A four-residue basic sequence (Arg-Ser-Lys-Arg) was identified upstream of the amino-terminal Asn of C5a, thereby specifying a beta alpha-chain orientation for the promolecule form of murine C5. The 3' end of this clone contained 351 base pairs of untranslated sequence. The presumed polyadenylation recognition site CATAAA was located 17 base pairs upstream of the poly(A) tail. Comparison of the derived murine C5 sequence with previously determined structures for murine C3 and C4 revealed regions of high sequence similarity, including the thiol ester region present in C3 and C4. The cysteine and proximal glutamine which give rise to the intramolecular thiol ester bond in C3 and C4 were absent in C5, having been replaced by serine and alanine, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1987

Molecular cloning of the cDNA encoding the Epstein-Barr virus/C3d receptor (complement receptor type 2) of human B lymphocytes.

Complementary DNA clones for complement receptor type 2 (CR2), the B-lymphocyte membrane protein that serves as the receptor for Epstein-Barr virus and the C3d complement fragment, were obtained by screening a lambda gt11 library generated from Raji B lymphoblastoid cell mRNA. A 4.2-kilobase (kb) clone, representing the entire coding sequence of the protein plus untranslated 5' and 3' nucleotide sequences was obtained and sequenced. The 4.2-kb clone, which contains all but about 500 base pairs (bp) of the 5' untranslated region of the full-length CR2 mRNA, consists of 63 bp of 5' untranslated nucleotide sequence followed successively by a start codon, a 20-amino acid hydrophobic signal peptide, 1005 amino acids having a repeating motif, a 28-amino acid probable transmembrane domain, and a 34-amino acid cytoplasmic tail. The deduced amino acid sequence of the protein indicates that the extracellular domain consists entirely of 16 tandemly arranged repeating elements, each 60-75 amino acids in length, which are identified by multiple conserved residues. This repeating motif also occurs in the C3b/C4b receptor, several complement proteins, and a number of noncomplement proteins. In CR2, the 16 repeats occur in four clusters of four repeats each. Approximately 10% of the deduced amino acid sequence, including the amino and carboxyl termini, was confirmed by amino acid sequencing of tryptic peptides derived from purified CR2. The nucleotide and derived amino acid sequence of CR2 and related studies are presented here.

Amino Acid Sequence↗