PubMed Health⌕ Search

Biomedical subjects

J B Cowland

Publications and source records attributed to J B Cowland.

12 recordsLinked to original sources
PubMed1998

Expression, purification, crystallization and crystallographic characterization of dimeric and monomeric human neutrophil gelatinase associated lipocalin (NGAL).

Crystals of the monomeric and dimeric forms of human neutrophil gelatinase associated lipocalin have been grown in hanging-drop vapor-diffusion trials using PEG as a precipitating agent with recombinant protein expressed in a baculovirus-based system. Crystals of monomeric NGAL belong to the cubic space group P432 with lattice constants a = b = c = 126.6 A; crystals of dimeric NGAL belong to the tetragonal space group P41212 (or its enantiomorph P43212) with lattice constants a = b = 54.14 and c = 121.56 A. Isomorphous crystals of the NGAL dimer can be grown in the presence of ligand: the tripeptide N-formyl-Met-Leu-Phe.

Acute-Phase Proteins↗
PubMed1997

Molecular characterization and pattern of tissue expression of the gene for neutrophil gelatinase-associated lipocalin from humans.

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa lipocalin first identified as a protein stored in specific granules of the human neutrophil. The protein is believed to bind small lipophilic substances such as bacterial derived formylpeptides and lipopolysaccharides (LPS) and might function as a modulator of inflammation. To characterize the regulation of NGAL further, we have cloned and sequenced a 5869-bp region of the NGAL gene including 1695 bp of the 5' nontranscribed region and a 3696-bp coding region encompassing seven exons and six introns. The transcriptional start sites were identified by an RNase protection assay. The NGAL gene is highly homologous to the mouse gene 24p3. NGAL was expressed in bone marrow and in tissues that are prone to exposure to microorganisms. Potential cis-acting elements were identified in the promoter region of the NGAL gene by computer analysis and include binding sites for CTF/CBP, the hematopoietic transcription factors GATA-1 and PU.1, and the LPS-inducible factor NF-kappa B.

Acute-Phase Proteins↗
PubMed1997

The human antibacterial cathelicidin, hCAP-18, is synthesized in myelocytes and metamyelocytes and localized to specific granules in neutrophils.

hCAP-18 is the only human member of the antibacterial and endotoxin-binding family of proteins known as cathelicidins. The antibacterial and endotoxin binding domains reside in the C-terminal 37 amino acids of the protein (LL-37) and this is believed to be unleashed from the neutralizing N-terminus by proteases from peroxidase positive granules. In human neutrophils, peroxidase positive and peroxidase negative granules can be subdivided into granule subsets that differ in protein content and ability to be exocytosed. To determine the localization of hCAP-18, we performed high-resolution immuno-electron microscopy and subcellular fractionation on Percoll density gradients. Biosynthesis of hCAP-18 was investigated in isolated human bone marrow cells. hCAP-18 was found to colocalize and comobilize with lactoferrin, but not with gelatinase in subcellular fractions. This was confirmed by electron microscopy. hCAP-18 is synthesized at the same stage of myeloid cell maturation as lactoferrin, and is efficiently targeted to granules. Like the peroxidase negative granule's matrix metalloproteinases, collagenase and gelatinase, hCAP-18 is also stored in unprocessed form. hCAP-18 is a major protein of specific granules where it is present in equimolar ratio with lactoferrin.

Antimicrobial Cationic Peptides↗
PubMed1997

An ELISA for hCAP-18, the cathelicidin present in human neutrophils and plasma.

hCAP-18 is a newly described protein of human neutrophilic granulocytes which belongs to the cathelicidin family of antimicrobial proteins. Members of this protein family share a common N-terminal sequence followed by a highly diverse antimicrobial, cationic C-terminus. The present work describes the production of recombinant hCAP-18, the generation of antibodies to the protein and the development of an accurate, sensitive and specific ELISA for the detection of hCAP-18 in cells, plasma and urine with a detection limit of 0.084 ng/ml. The amount of hCAP-18 in neutrophils is 0.627 microgram protein per 10(6) cells. The plasma level is 1.18 micrograms/ml which is several fold higher than for other neutrophil specific granule proteins. hCAP-18 is present in plasma as high molecular weight complexes. In accordance with this, hCAP-18 is barely excreted in the urine. The bone marrow appears to be the major source of plasma hCAP-18. The high level of hCAP-18 in plasma may provide an important defense against microorganisms and endotoxins.

Animals↗
PubMed1996

Targeting of proteins to granule subsets is determined by timing and not by sorting: The specific granule protein NGAL is localized to azurophil granules when expressed in HL-60 cells.

The mechanism of protein targeting to individual granules in cells that contain different subsets of storage granules is poorly understood. The neutrophil contains two highly distinct major types of granules, the peroxidase positive (azurophil) granules and the peroxidase negative (specific and gelatinase) granules. We hypothesized that targeting of proteins to individual granule subsets may be determined by the stage of maturation of the cell, at which the granule proteins are synthesized, rather than by individual sorting information present in the proteins. This was tested by transfecting the cDNA of the specific granule protein, NGAL, which is normally synthesized in metamyelocytes, into the promyelocytic cell line HL-60, which is developmentally arrested at the stage of formation of azurophil granules, and thus does not contain specific and gelatinase granules. Controlled by a cytomegalovirus promoter, NGAL was constitutively expressed in transfected HL-60 cells. This resulted in the targeting of NGAL to azurophil granules as demonstrated by colocalization of NGAL with myeloperoxidase, visualized by immunoelectron microscopy. This shows that targeting of proteins into distinct granule subsets may be determined solely by the time of their biosynthesis and does not depend on individual sorting information present in the proteins.

Acute-Phase Proteins↗
PubMed1996

SGP28, a novel matrix glycoprotein in specific granules of human neutrophils with similarity to a human testis-specific gene product and a rodent sperm-coating glycoprotein.

A novel 28 kDa glycoprotein was purified from exocytosed material from human neutrophils and its primary structure partially determined. Degenerate oligonucleotide primers were used to amplify cDNA clones from a human bone marrow cDNA library. The deduced 245 amino acid sequence of the 2124 bp full-length cDNA showed high degrees of similarity to the deduced sequences of human gene TPX-1 and of sperm-coating glycoprotein from rat and mouse. Subcellular fractionation of human neutrophils indicated that the protein is localized in specific granules. The protein was named SGP28 (specific granule protein of 28 kDa).

Amino Acid Sequence↗
PubMed1996

An efficient cellular system for mutational analysis of prohormone processing.

A novel system for heterologous expression of prohormones based on transient transfection of the HIT beta-cell line was established using human progastrin as a model. Progastrin was expressed at high levels compared to other gene transfer systems in endocrine cells, and the processing pattern was similar to that of normal antral gastrin cells. Thus, gastrin was partially tyrosine O-sulfated and carboxyamidated. Cell extracts contained mainly gastrin-17 and gastrin-34 and the corresponding glycine-extended forms. In contrast, the media contained more incompletely processed gastrin forms. This suggests that gastrin was directed to the regulated secretory pathway but that some progastrin products were constitutively secreted. Glucose increased both the level of gastrin gene expression and maturation to carboxyamidated peptides, indicating that glucose influences the activity of the amidation enzyme complex, peptidylglycine alpha-amidating mono-oxygenase (PAM), in insulin cells. Mutational analysis of tyrosine sulfation of gastrin demonstrated that substitution of the uncharged residue carboxy-terminal to the tyrosine with an acidic residue does not increase sulfation in contrast to previous results, where the amino-terminal residue was replaced with an acidic residue. The mutant peptides displayed sulfation-dependent processing, supporting our recent suggestion that tyrosine sulfation increases the proteolytic processing of prohormones.

Amino Acid Sequence↗
PubMed1995

hCAP-18, a cathelin/pro-bactenecin-like protein of human neutrophil specific granules.

A 19 kDa protein was identified in specific granules of human neutrophils. A full-length cDNA clone was isolated from a human CML cDNA library, based on amino-acid sequences of isolated tryptic fragments. This clone includes the recently identified cDNA for FALL-39/CAP-18. Aminoacid sequences of proteolytic fragments derived both from the conserved N-terminal cathelin-like region and the highly variable C-terminal region characteristic of this family of bactericidal, LPS binding proteins, were in complete agreement with the sequence deduced from the cDNA. Thus, the 19 kDa protein is hCAP-18, stored as a 'pro-peptide' in specific granules.

Amino Acid Sequence↗
PubMed1995

HLA-DQA1 typing in Danes by two polymerase chain reaction (PCR) based methods.

A total of 280 persons were HLA-DQA1 typed by two different polymerase chain reaction (PCR) based methods; (i) a reverse dot-blot (RDB) method, which can differentiate between six alleles, and (ii) a combined PCR-restriction fragment length polymorphism (PCR-RFLP) and allele-specific amplification (ASA) method, which together recognise eight alleles. In 146 unrelated Danish individuals, the HLA-DQA1 alleles were in Hardy-Weinberg equilibrium. For identity testing, the power of discrimination (PD) of HLA-DQA1 was 0.932 with the RDB method and 0.942 with the PCR-RFLP/ASA method. For paternity testing, the theoretical chance of exclusion in HLA-DQA1 of non-fathers was 0.634 with the RDB method and 0.660 with the PCR-RFLP/ASA method.

Alleles↗
PubMed1994

DNA polymorphism of HLA class II genes in systemic lupus erythematosus.

We investigated the DNA restriction fragment length polymorphism (RFLP) of the major histocompatibility complex (MHC) genes: HLA-DRB, -DQA, -DQB, -DPB in 24 Danish patients with systemic lupus erythematosus (SLE) and in 102 healthy Danes. A highly significant increase of the frequency of the DR3- and DRw6-associated 7.00 kb DRB TaqI DNA fragment was found in SLE patients compared to normal controls (83.3% vs 35.5%; RR = 9.1, p < 10(-4). The frequencies of the DQA1*0501-associated 4.56 kb DQA TaqI fragment and the DRB3*01/03-associated 9.79 kb TaqI fragment were also found to be significantly increased in SLE patients (70.8% vs 29.7%; RR = 5.8, p < 10(-2) for the DQA fragment and 70.8% vs 36.1%; RR = 4.3, p < 0.05 for the DRB3 fragment). Less extensive and insignificant increases of the frequencies of the DR3-associated DQB and DPB fragments were observed. The frequencies of the DR2-associated DRB, DQA, and DQB fragments were comparable to those found in normal controls.

DNA↗
PubMed1988

Human ubiquitin genes: one member of the UbB gene subfamily is a tetrameric non-processed pseudogene.

The human ubiquitin gene family consists of three subfamilies. One of these, the UbB subfamily, includes a functional gene coding for a polyubiquitin protein that contains three ubiquitin copies tandemly repeated, as well as three pseudogenes of the processed type. We have now isolated a fifth human UbB type gene, different from any of the previously identified ones. This newly isolated gene is a tetrameric pseudogene which has presumably arisen by unequal crossing-over of two ancestral trimeric alleles. Southern blotting data indicate that all members of the human UbB gene subfamily are now accounted for.

Adult↗