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Biomedical subjects

B Frangione

Publications and source records attributed to B Frangione.

At least 145 records · Page 8Linked to original sources
PubMed1992

Production of the Alzheimer amyloid beta protein by normal proteolytic processing.

The 4-kilodalton (39 to 43 amino acids) amyloid beta protein (beta AP), which is deposited as amyloid in the brains of patients with Alzheimer's diseases, is derived from a large protein, the amyloid beta protein precursor (beta APP). Human mononuclear leukemic (K562) cells expressing a beta AP-bearing, carboxyl-terminal beta APP derivative released significant amounts of a soluble 4-kilodalton beta APP derivative essentially identical to the beta AP deposited in Alzheimer's disease. Human neuroblastoma (M17) cells transfected with constructs expressing full-length beta APP and M17 cells expressing only endogenous beta APP also released soluble 4-kilodalton beta AP, and a similar, if not identical, fragment was readily detected in cerebrospinal fluid from individuals with Alzheimer's disease and normal individuals. Thus cells normally produce and release soluble 4-kilodalton beta AP that is essentially identical to the 4-kilodalton beta AP deposited as insoluble amyloid fibrils in Alzheimer's disease.

Alzheimer Disease↗
PubMed1992

Prion protein preamyloid and amyloid deposits in Gerstmann-Sträussler-Scheinker disease, Indiana kindred.

Gerstmann-Sträussler-Scheinker disease (GSS) is a familial neurological disorder pathologically characterized by amyloid deposition in the cerebrum and cerebellum. In GSS, the amyloid is immunoreactive to antisera raised against the prion protein (PrP) 27-30, a proteinase K-resistant peptide of 27-30 kDa that is derived by limited proteolysis from an abnormal isoform of a neuronal sialoglycoprotein of 33-35 kDa designated PrPSc. Polyclonal antibodies raised against synthetic peptides homologous to residues 15-40 (P2), 90-102 (P1), and 220-232 (P3) of the amino acid sequence deduced from hamster PrP cDNA were used to investigate immunohistochemically the distribution of PrP and PrP fragments in the brains of two patients from the Indiana kindred of GSS. Two types of anti-PrP-immunoreactive deposits were found: (i) amyloid deposits, which were exclusively labeled by anti-P1 antiserum to residues 90-102 of PrP, and (ii) preamyloid deposits, which were labeled by all anti-PrP antisera but did not exhibit the tinctorial and optical properties of amyloid. The latter appeared as diffuse immunostaining of the neuropil that targeted to areas in which amyloid deposits were most abundant. They were partially resistant to proteinase K digestion and consisted ultrastructurally of amorphous, flaky, electron-dense material. These findings substantiate our previous observation that the major amyloid component in the GSS Indiana kindred is an internal fragment of PrP and indicate that full-length abnormal isoforms of PrP and/or large PrP fragments accumulate in brain regions most affected by amyloid deposition. These findings support the view that in the GSS Indiana kindred a stepwise degradation of PrP occurs in situ in the process of amyloid fibril formation.

Aged↗
PubMed1992

A soluble form of prion protein in human cerebrospinal fluid: implications for prion-related encephalopathies.

The cellular prion protein (PrPc) is a 33-35 kDa sialoglycoprotein anchored to the external surface of neural and non-neural cells by a glycosyl phosphatidylinositol moiety. In addition, a secretory form of PrPc has been found in cell-free translation systems and in cell cultures. On this basis, we investigated human cerebrospinal fluid for the presence of soluble PrP and identified a protein whose molecular weight, antigenic determinants, N-terminal amino acid sequence and sensitivity to protease digestion corresponded to those of PrPc. In prion-related encephalopathies of humans and animals, the secretory form of PrPc might be converted into the abnormal isoform PrPSc and play a role in the dissemination of the disease process and amyloid formation.

Adolescent↗
PubMed1992

H chain V region sequences of three human monoclonal IgM with anti-myelin-associated glycoprotein activity.

The amino acid sequence corresponding to the V region H chain gene used by three monoclonal IgM directed to the myelin-associated glycoprotein (MAG) is presented. They all belonged to the VHIII variability subgroup, but each may well represent a new member of this family inasmuch as their homology with previously sequenced VHIII genes was less than 80%. Strikingly, there was no greater homology between the H chain V regions of the anti-MAG IgM. Partial amino acid sequence data indicated that these V regions were joined to as yet unidentified DH segments; however, two H chains used very similar DH, possibly indicating that this sequence was involved in the fine specificity of the IgM for MAG. All H chains included a JHIV region. These data, together with results obtained from the sequence of the three kappa L chains of the same IgM molecules (Mihaesco, E., H. Ayadi, N. Congy, M. C. Gendron, J. P. Roy, H. Heyermann, B. Frangione, and J. C. Brouet. 1989. J. Biol. Chem. 264:21481), indicate that the repertoire of VL and VH gene segments used by anti-MAG IgM is quite diverse, in contrast to previous structural data obtained for other human monoclonal IgM autoantibodies. Possibly, these differences reflect distinct pathogenesis.

Amino Acid Sequence↗
PubMed1992

Characterization of Alzheimer amyloid precursor protein transcripts in platelets and megakarocytes.

Immunoblot analyses indicate that the platelet is a reservoir of several Alzheimer amyloid precursor protein (APP) isoforms, including C-terminal reactive species which could potentially serve as the precursor of the amyloid beta protein (AB*) in Alzheimer's disease (AD). Since platelets are known to sequester several plasma proteins from the blood, we employed the polymerase chain reaction (PCR) to amplify reverse transcribed mRNA and detect the 3 major APP transcripts (APP695,751,770) in platelets and the Dami megakaryocyte cell line. PCR amplification of glycoprotein IIb and HLA-DR mRNA was used to demonstrate that APP transcripts were derived from cells of megakaryocytic lineage, and the results were compared with those obtained from peripheral blood mononuclear cells, human umbilical vein endothelial cells, B lymphocyte and astrocytoma cell lines. The identity of PCR products was confirmed by hybridization with APP specific oligonucleotide probes, and sequencing of amplified segments.

Amyloid beta-Protein Precursor↗
PubMed1992

Epitope map of two polyclonal antibodies that recognize amyloid lesions in patients with Alzheimer's disease.

Two synthetic peptides with sequences identical with those of fragments of the extracellular domain of the Alzheimer's-disease amyloid precursor protein (APP) were used to raise antibodies. SP28 comprises positions 597-624 of the APP695 isoform, whereas SP41 extends towards the N-terminus (amino acids 584-624) and contains the entire SP28 peptide. Using e.l.i.s.a. and inhibition experiments we identified the two beta-turn-containing segments 602-607 and 617-624 as the epitopes recognized by anti-SP41 and anti-SP28 respectively. Both antibodies immunolabelled amyloid lesions in brains from Alzheimer's-disease patients and patients with related disorders, whereas they were unreactive in control brains. However, when probed on immunoblots, anti-SP28 failed to detect full-length APP from baculovirus-infected Sf9 cells, and anti-SP41 reacted weakly compared with other anti-APP antisera. The data suggest that these antibodies are directed to conformational epitopes not existent in the native molecules but present after alternative APP processing.

Alzheimer Disease↗
PubMed1992

Apolipoprotein E: a pathological chaperone protein in patients with cerebral and systemic amyloid.

Many biochemically diverse proteins can give rise to amyloid fibrils; however, they are all accompanied by P component and glucosaminoglycans. With antibodies specific to apolipoprotein E (apo E) we used immunohistochemical techniques to test for the presence of this protein in both cerebral and systemic amyloid. We found apo E immunoreactivity in all tested types of cerebral and systemic amyloid. In amyloid deposits apo E P, component and glucosaminoglycans may be acting as 'pathological molecular chaperones'. The latter we define as a group of unrelated proteins that induce beta-pleated conformation in amyloidogenic polypeptides.

Amyloid↗
PubMed1992

Gelsolin gene mutation--at codon 187--in familial amyloidosis, Finnish: DNA-diagnostic assay.

Familial amyloidosis, Finnish (FAF), is an autosomal dominant form of systemic amyloidosis with lattice corneal dystrophy and progressive cranial neuropathy as principal clinical manifestations. We have shown that the novel amyloid fibril protein found in these patients is an internal degradation fragment of gelsolin, an actin-binding protein, and that it contains an amino acid substitution, asparagine for aspartic acid at position 15, that is due to a guanine-to-adenine transversion corresponding to codon 187 of human plasma gelsolin cDNA. To test that this mutation cosegregates with the disease high-molecular-weight genomic DNA was isolated from autopsied tissues or lymphocytes of 23 patients, 6 healthy relatives and 20 unrelated healthy control persons. Specific fragments were amplified with the polymerase chain reaction for oligonucleotide hybridization analysis using the slot-blot technique. The guanine-to-adenine transversion was found in all FAF patients tested, but in none of the control subjects. Our results show that the mutation (G to A) cosegregates with the disease phenotype, and that the slot-blot analysis can be used as a diagnostic assay, including prenatal evaluation.

Amyloidosis↗
PubMed1992

Franklin's disease: Ig gamma 2 H chain mutant BUR.

The complete sequence of a gamma 2-H chain disease protein BUR is presented. This mutant, a dimer of a 348-residue chain, linked by four disulfide bridges, is composed of a complete V region, hinge, CH2, and CH3 domains. There is one deletion, the CH1 domain, which includes the cysteine residue bridging the H to L chain. Although the V region is encoded by the VHI and JHIII genes, it has several distinctions: methionine at position 11, two unique cysteine residues in the second complementarity determining region (CDR2), and three glycosylation sites, two of which are located in the CDR2 and CDR3 regions. These distinctive characteristics of BUR VH within the framework of a normal VHI may be affected by extensive somatic mutation or by a rare and previously unanalyzed VH gene.

Amino Acid Sequence↗
PubMed1992

Localization of the cleavage sites on fibronectin following digestion by urokinase.

Urokinase (u-PA) proteolytically cleaves both human plasma (pFn) and cellular (cFn) dimeric fibronectin (M(r) 440,000) into four major polypeptides of approximately M(r) 210,000, 200,000, 25,000, and 6,000. Amino acid sequence analysis of the polypeptide fragments indicated that the enzymatic cleavage of Fn occurs at two sites: 1) between an arginine/alanine peptide bond located C-terminal to residue 259; this cleavage liberates the N-terminal M(r) 25,000 fragment and the M(r) 210,000 and M(r) 200,000 polypeptides derived from the A and B chains of Fn, respectively; and 2) between an arginine/threonine peptide bond located C-terminal to residue 2,299, thereby yielding an M(r) 6,000 dimeric fragment containing the C-terminal interchain disulfide bonds. Predigestion of Fn with u-PA increased the molecule's vulnerability to further attack by the enzymes plasmin and cathepsin D. These data provide further biochemical evidence for the proteolytic cleavage of fibronectin by plasminogen activators and substantiate that u-PA digestion of Fn may be an initial event in the local degradation of the extracellular matrix by malignant cells, possessing elevated levels of these enzymes.

Amino Acid Sequence↗
PubMed1992

Molecular biology of Alzheimer's amyloid--Dutch variant.

Hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D) (or familial cerebral amyloid angiopathy) and familial Alzheimer's disease (FAD) share several properties. Both are autosomal dominant forms of cerebral amyloidosis characterized by beta-amyloid (A beta) deposition. In HCHWA-D the A beta is predominantly found in blood vessels and in early parenchymal plaques, whereas in AD parenchymal A beta deposits in the form of senile plaques and neurofibrillary tangles are a more prominent finding. Point mutations in the amyloid precursor protein (APP) have recently been described, in both conditions. A G to C transversion at codon 618 (extracellular portion of APP695), producing a single amino acid substitution of glutamine instead of glutamine acid, occurs in HCHWA-D; whereas mutations at codon 642 in the intramembrane region of APP695 (phenylalanine, isoleucine, or glycine instead of valine) are associated with early onset FAD. This suggests that the site of particular mutations in the APP gene and the type of amino acid substitution in the APP holoprotein are more important in determining clinicopathological phenotype and age at which A beta is deposited. Thus FAD and HCHWA-D can be regarded as two sides of the same coin.

Alzheimer Disease↗
PubMed1992

The heterogeneity of bovine IgG2--V. Differences in the primary structure of bovine IgG2 allotypes.

The partial amino acid sequences of the gamma chains of the bovine IgG2a(A1) and IgG2a(A2) allotypes were determined. Sequence differences were found in the CH1 domain, the hinge region, and the CH3 domain. The hinge regions displayed only 71.4% similarity and all of the differences were of a radical nature. The A2 hinge has isoleucine instead of serine at 229, histidine for asparagine at 235, proline for histidine at 238, and cysteine instead of proline in position 234; the latter has the potential for forming an additional interheavy chain disulphide bridge. The occurrence of such a bridge could explain the presence of a pepsin fragment consisting of the hinge region and the Fc. A corresponding fragment is not obtained with the A1 allotype. Both allotypes have a shortened hinge region and a truncated CH2 domain. This feature is characteristic of all reported sequences of IgG2 proteins but not IgG1 in cattle and the goat. This structural feature may be important in subclass-specific recognition by Fc gamma receptors in ruminants. A surprising discovery was the occurrence of five substitutions in the CH3 domain of the IgG2a(A2) in comparison with the A1, which are shared with the CH3 of IgG1. These permit the occurrence of isoallotypic determinants and can explain the difficulty encountered in preparing A2-specific antisera during which adsorption with IgG1 is a routine procedure. The primary sequence data we report confirm the presence of major structural differences between the A allotypes of cattle that was suggested by previous work. The sequence of the A1 allotype most closely agrees with the two IgG2 sequences deduced from their nucleotide sequences whereas the sequence differences in the hinge and C-terminal CH3 make IgG2a(A2) unique. The structural differences between allotypes could have major consequences for such biological activities as phagocytosis, transepithelial transport, lymphocyte and complement activation.

Amino Acid Sequence↗
PubMed1992

Amyloidoma of the CNS. II. Immunohistochemical and biochemical study.

We present the immunohistochemical and biochemical identification of an amyloidoma localized to the cerebral white matter in a patient who shows no evidence of systemic or extracranial localized amyloid deposits. Immunohistologic and immunochemical studies, using antibodies against biochemically different amyloid fibrils and amyloid-associated proteins, showed reactivity with antibodies only to lambda light chain and serum amyloid P-component. Amino acid sequence analysis of the purified amyloid fibrils extracted from the brain tumor indicates that the amyloid protein is an unusual immunoglobulin lambda light chain, starting at residue five of the variable domain. These fibrils consist of lambda chain fragments of different lengths (10 to 30 kd) very likely arising by polymerization of the amyloid subunit or sequential proteolytic cleavage of the light chain, or both. After exposure to denaturing agents, the 10-kd subunit retains the characteristics of native amyloid fibrils by electron microscopy.

Adult↗
PubMed1992

Beta protein precursor expression in human platelets and a megakaryocyte cell line. Possible implications for the origin of cerebral amyloidosis in Alzheimer's disease.

BACKGROUND: The origin of the amyloid beta protein (A beta) that is the main constituent of amyloid fibrils occurring in the senile plaques and cerebrovasculature of individuals afflicted with Alzheimer's Disease, Down's Syndrome, Hereditary Cerebral Hemorrhage with Amyloidosis--Dutch Type, and Sporadic Cerebral Amyloid Angiopathy, is central to the pathogenesis of these disorders. Evidence exists to support a neuronal and/or a vascular origin. We have reported that platelets may serve as one possible source of the A beta sequence via an intact, membrane-associated Beta Protein Precursor (beta PP) which is encoded by a platelet transcript (BBRC 173:1292-1298, 1990). EXPERIMENTAL DESIGN: Immunoaffinity chromatography and western blotting of extracted cellular proteins, polymerase chain reaction amplification of beta PP mRNA, fluorescence activated flow cytometric analysis, and confocal scanning laser microscopy have been employed to characterize the presence and distribution of thrombocytic beta PP. RESULTS: Immunoblot analysis with antibodies specific for the carboxyl-terminal end of beta PP indicates that platelets and the Dami megakaryocyte cell line express membrane-associated species of intact beta PP ranging in molecular weight from 110 to 140 kilodaltons (kd), as well as carboxyl-terminal reactive forms ranging from 16 to 22 kd. Thrombin stimulation of platelets induces the release of five soluble beta PP species, which possess apparent isofocusing points in the range of 4.1-5.5. By contrast, extracts of peripheral blood mononuclear cells enriched by ficoll centrifugation, endothelial cells and a B cell line were not immunoreactive by western blot, even though beta PP transcripts could be amplified by polymerase chain reaction. The distribution of platelet beta PP was localized by flow cytometric analysis and scanning laser microscopy, using fluorescein-labeled antibodies. Study of the subcellular distribution of platelet beta PP indicates that these translation products are accumulated in discrete foci throughout the thrombocyte, possibly corresponding to secretory granules. CONCLUSIONS: The size of the carboxyl-terminal forms of beta PP indicate that the A beta sequence is present as a membrane associated constituent in unstimulated platelets, and may represent alternative pathways of beta PP processing. Cleavage or other abnormal processing of platelet-associated beta PP in Alzheimer's disease provides one mechanism whereby cerebral amyloid might derive from the circulation.

Alzheimer Disease↗
PubMed1991

Isolation and amino terminal sequence of beta-trace, a novel protein from human cerebrospinal fluid.

beta-Trace, a 23.5 kDa glycoprotein of unknown biological functions, is present in all body fluids tested. It is found in higher concentration in human seminal fluid and cerebrospinal fluid (CSF) than in serum. A one-step procedure for the isolation of beta-trace from pooled CSF is described, by affinity chromatography using a specific antibody made against beta-trace. Amino terminal sequence analysis yields the sequence A P E A Q V S V Q P N F Q Q D K F L G with no homology to known proteins, indicating that beta-trace is a novel CSF protein.

Amino Acid Sequence↗