Three new rare variants of alpha 1-antitrypsin

Toxicological response of the model fungus Saccharomyces cerevisiae to different concentrations of commercial graphene nanoplatelets

Graphene nanomaterials have attracted a great interest during the last years for different applications, but their possible impact on different biological systems remains unclear. Here, an assessment to understand the toxicity of commercial polycarboxylate functionalized graphene nanoplatelets (GN) on the unicellular fungal model Saccharomyces cerevisiae was performed. While cell proliferation was not negatively affected even in the presence of 800 mg L-1 of the nanomaterial for 24 hours, oxidative stress was induced at a lower concentration (160 mg L-1), after short exposure periods (2 and 4 hours). No DNA damage was observed under a comet assay analysis under the studied conditions. In addition, to pinpoint the molecular mechanisms behind the early oxidative damage induced by GN and to identify possible toxicity pathways, the transcriptome of S. cerevisiae exposed to 160 and 800 mg L-1 of GN was studied. Both GN concentrations induced expression changes in a common group of genes (337), many of them related to the fungal response to reduce the nanoparticles toxicity and to maintain cell homeostasis. Also, a high number of genes were only differentially expressed in the GN800 condition (3254), indicating that high GN concentrations can induce severe changes in the physiological state of the yeast.

Convenient high-resolution isoelectric focusing (IEF) method for the separation of alpha1-proteinase inhibitor (A1PI) isoforms in A1PI concentrates

Currently, high-resolution separation of A1PI is done in highly specialized laboratories using gels made in-house. This paper presents a high-resolution method for the separation of A1PI concentrates and human plasma using commercially available gels. Hybrid IEF was performed with carrier ampholytes and the gels were stained with Coomassie Brilliant Blue G-250. In addition, a sensitive immunoblotting procedure is described. The IEF method allowed the reproducible and convenient determination of the IEF pattern of A1PI in concentrates including resolution of glycan-dependent isoforms and isoproteins with secondary modifications such a C-terminal Lys-truncation. Furthermore, a shift in the IEF pattern of A1PI occurring upon reduction could be detected. Finally, in combination with a sample pretreatment step, the method proved able to monitor complex A1PI isoform patterns in samples with low A1PI concentrations as present for example in bronchoalveolar lavage solutions.

Function of a rare variant of alpha-1-antitrypsin, phenotype P(i) EFranklin S, a poor inhibitor of human neutrophil elastase

A 31-year-old woman with the rare alpha-1-antitrypsin (A1AT) phenotype P(i) EFranklin S presented to this laboratory. Since little is known about the EFranklin protein, a study was established to investigate the biochemical properties of this glycoprotein, notably its inhibitory activity against human neutrophil elastase (HNE), compared with that of the more common A1AT variants M and Z. The serum A1AT level of 1.8 g/l (reference range 0.8-2.2 g/l) and anti-neutrophil elastase capacity (ANEC) value of 28 microM (reference range 15-42 microM) of this variant were normal. However, the association rate constant (AC) of the isolated and purified EFranklin protein 2.7 (0.4) x 10(6) M-1 s-1 at 25 degrees C was significantly lower compared with that in the normal M variant 9.1 (0.9) x 10(6) M-1 s-1. This implies that this form of A1AT is expressed at normal levels in serum but is functionally impaired as an inhibitor of HNE. The in vivo serum inhibition time of HNE was estimated to be 66 ms for the purified EFranklin protein compared with 20 ms for the M protein. While this protein is not an efficient inhibitor of HNE, there are sufficient molecules in the serum to achieve 100% inhibition of HNE and to protect the lung against proteinase attack. In conclusion, individuals who inherit the rare EFranklin variant in conjunction with the M or S A1AT molecules do not appear to have a high risk for the development of emphysema.

Genetic diversity from a limited repertoire of mutations on different common allelic backgrounds: alpha 1-antitrypsin deficiency variant Pduarte

alpha 1-Antitrypsin (alpha 1AT) is one of the most polymorphic gene loci in the human genome. alpha 1AT variants are typically identified by their migration position in an isoelectric focusing gel at pH 4-5. Heterogeneity of the isoelectric point of alpha 1AT variants, hence variant migration, most often results from amino acid substitutions which alter the net charge of the molecule. We identified an individual heterozygous for an alpha 1AT variant migrating in the "P" variant region which differs from other known "P" variants. Using isoelectric focusing on an immobilized pH gradient at pH 4.50-4.85 the novel P allele, Pduarte, migrates between Pst. albans and Plowell. Densitometric analysis of normal "M" type alpha 1AT and the deficiency variant Plowell major bands separated by isoelectric focusing demonstrates that Pduarte contributes approximately 41% as much alpha 1AT to the total serum alpha 1AT concentration as the normal "M" alpha 1AT, similar to Plowell. Direct DNA sequencing of the proband's genomic DNA demonstrates that the Pduarte allele differs from the normal M1 (V213) allele by two amino acid substitutions, R101 (CGT)-->H(CAT) and D256 (GAT)-->V(GTT). Individually, these amino acid substitutions characterize the normal M4 allele (R101-->H) and the deficient Plowell allele (D256-->V). Thus the Pduarte allele differs from the Plowell allele only by the normal allelic background in which the V256 mutation occurs. Comparison of amino acid sequences among several alpha 1AT variants demonstrates that Pduarte is an example of a more general observation regarding diversity within the PI (protease inhibitor) system.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-1-antitrypsin phenotypes in Saudi Arabia: A study in the central province

This study was conducted on 204 plasma samples obtained from Saudis living in the central province of Saudi Arabia, to determine the prevalence of alpha-1-antitrypsin (alpha1AT) phenotypes. The alpha1AT phenotypes were separated by isoelectric focusing on ampholine gels (pH 4-5). The prevalences of PiMM, MS, MZ, SZ, and ZZ were 0.8676, 0.0931, 0.0245, 0.0098, and 0.0049, respectively. The gene frequencies of the alpha1AT variants, i.e.., PiM, PiS, and PiZ, were 0.9265, 0.0515, 0.022, respectively. We describe and compare our results in a Saudi population with those reported for other populations.

Molecular basis of alpha-1-antitrypsin deficiency

Alpha-1-antitrypsin (A1AT) deficiency is an autosomal hereditary disorder associated with a major reduction in serum A1AT levels. Clinically, A1AT deficiency is associated with emphysema in adults and, less commonly, liver disease in neonates. A1AT is a 52-kDa, 394-amino acid, single-chain glycoprotein normally present in serum at 150 to 350 mg/dl. The A1AT gene, composed of seven exons dispersed over 12 kb of chromosomal segment 14q31-32.3, is expressed in hepatocytes and mononuclear phagocytes. The A1AT protein, a member of the class of protease inhibitor proteins known as serpins (serine protease inhibitors), is a globular molecule composed of nine alpha-helices and three beta-pleated sheets. The major function of A1AT is to inhibit neutrophil elastase; A1AT does so through an active site centered around Met358 contained within an external stressed loop on the surface of the molecule. A1AT is a highly pleomorphic protein with greater than 75 variants determined at the protein and/or gene level. These variants can be categorized into four groups according to their serum A1AT level and function: normal, deficient, dysfunctional, and absent. There are two important salt bridges within the A1AT molecule (Glu342-Lys290; Glu263-Lys387); a mutation in the A1AT gene causing disruption of either salt bridge causes distinct molecular pathology resulting in reduced serum A1AT levels. Clinically relevant variants can be distinguished by a combination of isoelectric focusing of serum, restriction fragment length analysis of genomic DNA, oligonucleotide probes, and direct sequencing of the variant A1AT genes.

Diffuse hepatocellular dysplasia and carcinoma associated with the Mmalton variant of alpha 1-antitrypsin

The cirrhosis and hepatocellular carcinoma associated with alpha 1-antitrypsin deficiency has been exclusively reported with the PI Z allele. We present a 63-yr-old white man with emphysema, cirrhosis, and hepatocellular carcinoma. The latter occurred on a background of diffusely distributed hepatocellular dysplasia. Serum protein electrophoresis suggested a deficiency of alpha 1-antitrypsin quantitated at 13% of normal. PI phenotyping showed that he had only the rare PI Mmalton allele, previously associated only with severe lung disease. Family studies demonstrated the distribution of this rare allele. The liver at autopsy displayed well-differentiated hepatocellular carcinoma in addition to alpha 1-antitrypsin deposits in normal, dysplastic, and malignant cells.

Alpha-1-antitrypsin types in five Chinese national minorities

The frequencies of alpha-1-antitrypsin alleles were determined for five Chinese national minorities: Uigur, Korean, Mongolian, Chuang, and Li. PI S and PI Z alleles are not found in the five populations studied. PI ETOK allele is present in Korean, Mongolian, and Chuang populations, and Etokyo is a very common alpha-1-antitrypsin variant in Chinese. Other alleles which occur in more than one of the minorities are PI X (Mongolian and Chuang) and PI M4 (Korean and Uigur). The high frequency of PI M4 in the Uigur population suggests a probably Occidental origin of this nationality.

A new alpha 1-antitrypsin allele PI Poki: isoelectric focusing with immobilized pH gradients as a tool for identification for PI variants

A new rare genetic variant PI Poki in the protease inhibitor system found in two Japanese subjects, was compared with some PI P variants using several electrophoresis systems. Although this variant was slightly anodal to P by separator isoelectric focusing, it could be readily distinguished by isoelectric focusing with immobilized pH gradients: the mobility of Poki became cathodal to P. This method proved to be a powerful tool for identification of PI variants.

PI*LBEI and PI*JHOU: two new alpha-1-antitrypsin alleles

Two new variants of alpha-1-antitrypsin were found in a Chinese population by isoelectric focusing in polyacrylamide gel. They have been named Lbeijing (PI*LBEI) and Jhouyao (PI*JHOU) respectively. With the samples reduced and alkylated, both the variants were anodal to M1 and cathodal to L. Omitting the alkylation step, however, the relative mobilities of L and Jhouyao were altered. Under this condition, a characteristic of Jhouyao was revealed by isoelectric focusing in immobilized pH gradient 4.4-4.9, i.e., while its band 6 became anodal to L, band 4 was still cathodal to L.

PI(alpha 1-antitrypsin) polymorphism in the Japanese: confirmation of PI*M4 and description of new PI variants

PI phenotyping by separator isoelectric focusing (SIEF) was performed on a total of 1000 unrelated Japanese individuals from two different areas of Western Japan. The PI M1M4 subtype was observed together with the six common PI M subtypes. PI*M4 was confirmed to be present but rare in the Japanese. Several new PI variants were identified by comparison runs of each variant with previously reported genetic variants. The significance of treatment of serum with dithiothreitol (DTT) followed by iodacetic acid (IAC) in determination of PI variants is also described.