Expression Of Α1-antitrypsin Research Articles

Sentinel supervised lung-on-a-chip: A new environmental toxicology platform for nanoplastic-induced lung injury

Nanoplastics are prevalent in the air and can be easily inhaled, posing a threat to respiratory health. However, there have been few studies investigating the impact of nanoplastics on lung injury, especially chronic obstructive pulmonary disease (COPD). Furthermore, cell and animal models cannot deeply understand the pollutant-induced COPD. Existing lung-on-a-chip models also lack interactions among immune cells, which are crucial in monitoring complex responses. In the study, we built the lung-on-a-chip to accurately recapitulate the structural features and key functions of the alveolar-blood barrier while integrating multiple immune cells. The stability and reliability of the lung-on-a-chip model were demonstrated by toxicological application of various environmental pollutants. We Further focused on exploring the association between COPD and polystyrene nanoplastics (PS-NPs). As a result, the cell viability significantly decreased as the concentration of PS-NPs increased, while TEER levels decreased and permeability increased. Additionally, PS-NPs could induce oxidative stress and inflammatory responses at the organ level, and crossed the alveolar-blood barrier to enter the bloodstream. The expression of α1-antitrypsin (AAT) was significantly reduced, which could be served as early COPD checkpoint on the lung-chips. Overall, the lung-on-a-chip provides a new platform for investigating the pulmonary toxicity of nanoplastics, demonstrating that PS-NPs can harm the alveolar-blood barrier, cause oxidative damage and inflammation, and increase the risk of COPD.

Secretoglobin 3A2 protects lung from developing cigarette smoke-induced pulmonary emphysema.

Secretoglobin (SCGB) 3A2 is a bioactive molecule exhibiting various functions such as improving allergic airway inflammation and pulmonary fibrosis and promoting bronchial branching and proliferation during lung development. To determine if and how SCGB3A2 is involved in chronic obstructive pulmonary disease (COPD), a multifactorial disease with both airway and emphysematous lesions, a COPD mouse model was created by exposing Scgb3a2-deficient (KO), Scgb3a2-lung-specific overexpressing (TG), and wild type (WT) mice to cigarette smoke (CS) for 6 months. The KO mice showed loss of lung structure under control condition, and CS exposure resulted in more expansion of airspace and destruction of alveolar wall than WT mouse lungs. In contrast, TG mouse lungs showed no significant changes after CS exposure. SCGB3A2 increased the expression and phosphorylation of signal transducers and activators of transcription (STAT)1 and STAT3, and the expression of α1-antitrypsin (A1AT) in mouse lung fibroblast-derived MLg cells and mouse lung epithelial-derived MLE-15 cells. In MLg cells, A1AT expression was decreased in Stat3-knockdown cells, and increased upon Stat3 overexpression. STAT3 formed a homodimer when cells were stimulated with SCGB3A2. Chromatin immunoprecipitation and reporter assays demonstrated that STAT3 binds to specific binding sites on the Serpina1a gene encoding A1AT and upregulates its transcription in lung tissues of mice. Furthermore, nuclear localization of phosphorylated STAT3 upon SCGB3A2 stimulation was detected by immunocytochemistry. These findings demonstrate that SCGB3A2 protects the lungs from the development of CS-induced emphysema by regulating A1AT expression through STAT3 signaling.

Environmental concentration of spray paint particulate matters causes pulmonary dysfunction in human normal bronchial epithelial BEAS-2B cell

In addition to airborne particulate matter (PM), exposure to spray paint PMs (SPPMs) may also be associated with pulmonary dysfunction. In this study, we employed human normal bronchial epithelial BEAS-2B cells to elucidate the association between pulmonary toxicity and different sizes of SPPMs (SPPM10-3.2, SPPM3.2-1 and SPPM1) under realistic environmental concentrations in a spray paint factory. Results indicated that all SPPMs (20–100μg/cm2) induced significant decreases in cell viability (> 70% compared to the control), except for low-dose SPPM10-3.2 (20 and 50μg/cm2). Almost all SPPMs (20μg/cm2 and 100μg/cm2) induced oxidative stress (2–4 times that of the control), which increased the production of proinflammatory cytokines (1.5–4.5 times that of the control) as well as increased α1-antitrypsin expression (3–4.5 times that of the control). Moreover, we found that almost all SPPMs induced pulmonary epithelial barrier dysfunction (0.77–0.11 times that of the control) through the depletion of zonula occludens proteins (0.8–0.65 times that of the control). In conclusion, smaller SPPMs induced more severe adverse pulmonary adverse effects. Exposure to SPPM1 was a potential major risk factor for pulmonary epithelial barrier dysfunction. Our evidence demonstrates that exposure to SPPMs, especially SPPM1, may increase the risk of pulmonary dysfunction.

Correction to: Genetically engineered cell lines for α1-antitrypsin expression.

In the original publication of the article, the Acknowledgement section was published incompletely. The complete Acknowledgement is given in this Correction.

Genetically engineered cell lines for α1-antitrypsin expression.

To establish genetically modified cell lines that can produce functional α1-antitrypsin (AAT), by CRISPR/Cas9-assisted homologous recombination. α1-Antitrypsin deficiency (AATD) is a monogenic heritable disease that often results in lungs and liver damage. Current augmentation therapy is expensive and in short of supply. To develop a safer and more effective therapeutic strategy for AATD, we integrated the AAT gene (SERPINA1, NG_008290.1) into the AAVS1 locus of human cell line HEK293T and assessed the safety and efficacy of CRISPR/Cas9 on producing potential therapeutic cell lines. Cell clones obtained had the AAT gene integrated at the AAVS1 locus and secreted approx. 0.04 g/l recombinant AAT into the medium. Moreover, the secreted AAT showed an inhibitory activity that is comparable to plasma AAT. CRISPR/Cas9-mediated engineering of human cells is a promising alternative for generating isogenic cell lines with consistent AAT production. This work sheds new light on the generation of therapeutic liver stem cells for AATD.

Polycyclic aromatic hydrocarbons are associated with increased risk of chronic obstructive pulmonary disease during haze events in China

Although exposure to particulate matter with a diameter of <2.5μm (PM2.5) is associated with chronic obstructive pulmonary disease (COPD), the major components of PM2.5 in COPD pathogenesis are controversial. Here we employed the human lung epithelial cell line BEAS-2B to elucidate the association between COPD and the organic and water-soluble components of PM2.5. We found that the PM2.5 organic extract was a potential major risk factor for pulmonary epithelial barrier dysfunction through the depletion of proteins from the zonula occludens. This extract induced severe oxidative stress that increased DNA damage and the production of proinflammatory cytokines by BEAS-2B cells as well as decreased α1-antitrypsin expression, suggesting a mechanism that increases the risk of COPD. These effects were mainly mediated by polycyclic aromatic hydrocarbons (PAHs) through the aryl hydrocarbon receptor pathway. PAHs with high benzo(a)pyrene (BaP)-equivalent concentrations, but not major PAH components, have an increased risk of causing COPD, suggesting that BaP-equivalent concentrations represent a PM2.5-induced COPD risk metric, which may contribute to provide a rationale for the remediation of air pollution.

EGCG reverses human neutrophil elastase-induced migration in A549 cells by directly binding to HNE and by regulating α1-AT.

Lung carcinogenesis is a complex process that occurs in unregulated inflammatory environment. EGCG has been extensively investigated as a multi-targeting anti-tumor and anti-inflammatory compound. In this study, we demonstrated a novel mechanism by which EGCG reverses the neutrophil elastase-induced migration of A549 cells. We found that neutrophil elastase directly triggered human adenocarcinoma A549 cell migration and that EGCG suppressed the elevation of tumor cell migration induced by neutrophil elastase. We observed that EGCG directly binds to neutrophil elastase and inhibits its enzymatic activity based on the CDOCKER algorithm, MD stimulation by GROMACS, SPR assay and elastase enzymatic activity assay. As the natural inhibitor of neutrophil elastase, α1-antitrypsin is synthesized in tumor cells. We further demonstrated that the expression of α1-antitrypsin was up-regulated after EGCG treatment in neutrophil elastase-treated A549 cells. We preliminarily discovered that the EGCG-mediated induction of α1-antitrypsin expression might be correlated with the regulatory effect of EGCG on the PI3K/Akt pathway. Overall, our results suggest that EGCG ameliorates the neutrophil elastase-induced migration of A549 cells. The mechanism underlying this effect may include two processes: EGCG directly binds to neutrophil elastase and inhibits its enzymatic activity; EGCG enhances the expression of α1-antitrypsin by regulating the PI3K/AKT pathway.

Function of monocytes and monocyte-derived macrophages in α1-antitrypsin deficiency.

α1-antitrypsin deficiency is the most widely recognised genetic disorder causing chronic obstructive pulmonary disease (COPD). Mutant Z α1-antitrypsin expression has previously been linked to intracellular accumulation and polymerisation of this proteinase inhibitor. Subsequently, this has been described to underlie an exaggerated endoplasmic reticulum stress response and enhanced nuclear factor-κB signalling. However, whether monocyte-derived macrophages display the same features remains unknown. Monocytes from homozygous PiZZ α1-antitrypsin deficiency patients and PiMM controls were cultured for 6 days in the presence of granulocyte-macrophage or macrophage colony-stimulating factor to obtain pro- and anti-inflammatory macrophages (mφ-1 and mφ-2, respectively). We first showed that, in contrast to monocytes, pre-stressed mφ-1 and mφ-2 from healthy blood donors display an enhanced endoplasmic reticulum stress response upon a lipopolysaccharide trigger (XBP1 splicing, CHOP, GADD34 and GRP78 mRNA). However, this endoplasmic reticulum stress response did not differ between monocyte-derived macrophages and monocytes from ZZ patients compared to MM controls. Furthermore, these ZZ cells do not secrete higher cytokine levels, and α1-antitrypsin polymers were not detectable by ELISA. These data suggest that monocyte-derived macrophages are not the local source of Z α1-antitrypsin polymers found in the lung and that endoplasmic reticulum stress and pro-inflammatory cytokine release is not altered.

Human thyroxine binding globulin (TBG) promoter directs efficient and sustaining transgene expression in liver-specific pattern

The liver performs a vital role in metabolic process, which makes it an attractive target organ for gene therapy. To improve the effects of gene therapy in disorders caused by metabolic disturbance, we quantitatively evaluated six promoters, CMV, EF1α, PGK, apoE, thyroxine binding globulin (TBG), and cytochrome P450 2E1 (CYP2E1) by measuring the expression of α1-antitrypsin, which is controlled by these promoters and introduced via a lentivirus-mediated delivery system in the liver. The results showed that the TBG promoter presents as highly active though in general it is slightly lower than the ubiquitous CMV and EF1α. The expression of exogenous genes driven by the TBG promoter demonstrates to be much higher than by PGK, apoE, and CYP2E1 promoters, and the fragment of −435bp to −26bp from transcription start site (TSS) in the TBG promoter region is identified as the optimum region to direct transgene expression at a higher level. In addition, we further confirmed that the TBG promoter confers transgene persistent and specific expression within the liver up to several months after integration. The data suggests that the TBG promoter is a valuable tool and will greatly facilitate the optimization of vector design in hepatic gene therapy.

Curcumin inhibits tumor proliferation induced by neutrophil elastase through the upregulation of α1-antitrypsin in lung cancer

Lung carcinogenesis is a complex process in an unregulated inflammatory environment. Curcumin has been extensively investigated as a multi-target anti-tumor and anti-inflammation compound. In this paper, we demonstrate a novel inflammation-related mechanism for curcumin-induced inhibition of lung tumor growth. We found that neutrophil elastase, an important regulator of inflammatory processes, directly triggered tumor cell proliferation in human lung adenocarcinoma A549 cells, and curcumin could completely suppress the excess tumor proliferation induced by neutrophil elastase. α1-antitrypsin is synthesized by tumor cells and is the natural inhibitor of neutrophil elastase. We found that curcumin counteracted the decrease of α1-antitrypsin induced by neutrophil elastase by inducing the promoter activity of α1-antitrypsin and promoting its expression in A549 cells. The inhibition of neutrophil elastase-induced proliferation by curcumin was dependent on the PI3K/Akt pathway. Knockdown of α1-antitrypsin by siRNA further enhanced the tumor cell proliferation induced by neutrophil elastase and significantly blocked the anti-proliferation effect of curcumin against neutrophil elastase. Curcumin remarkably inhibited the primary tumor growth of Lewis lung carcinoma (LLC) in C57BL/6 mice. We further showed that curcumin upregulated the level of α1-antitrypsin in primary tumor tissue by promoting its local expression, and the protein level of neutrophil elastase in tumor tissue was obviously decreased in mice treated with curcumin. Overall, our results suggest that neutrophil elastase and α1-antitrypsin play important roles in modulating lung tumor proliferation in inflammatory microenvironment and curcumin inhibits neutrophil elastase-induced tumor proliferation via upregulating α1-antitrypsin expression in vitro and in vivo.

Long-term Physiologically Regulated Expression of the Low-density Lipoprotein Receptor In Vivo Using Genomic DNA Mini-gene Constructs

Familial hypercholesterolemia (FH) is a condition caused by mutations in the low-density lipoprotein receptor (LDLR) gene. Expression of LDLR is highly regulated and excess receptor expression is cytotoxic. To incorporate essential gene regulation into a gene therapy vector for FH, we generated vectors in which the expression of therapeutic human LDLR gene, or luciferase reporter gene, is driven by 10 kb of human LDLR genomic DNA encompassing the promoter region including elements essential for physiologically regulated expression. Using luciferase expression and specific LDL binding and internalization assays, we have shown in vitro that the genomic promoter element confers long-term, physiologically regulated gene expression and complementation of receptor deficiency in culture for 240 cell-generations. This was demonstrated in the presence of sterols or statins, modifiers of LDLR promoter activity. In vivo, we demonstrate efficient liver-specific delivery and expression of luciferase following hydrodynamic tail-vein injection and confirm that expression from the LDLR promoter element is sensitive to statin administration. We also demonstrate long-term LDLR expression from the 10-kb promoter element up to 9 months following delivery. The vector system that we describe provides the efficient delivery, long-term expression, and physiological regulation required for a successful gene therapy intervention for FH.

Sexually Dimorphic Patterns of Episomal rAAV Genome Persistence in the Adult Mouse Liver and Correlation With Hepatocellular Proliferation

Recombinant adeno-associated virus vectors (rAAVs) show exceptional promise for liver-targeted gene therapy, with phenotype correction in small and large animal disease models being reported with increasing frequency. Success in humans, however, remains a considerable challenge that demands greater understanding of host-vector interactions, notably those governing the efficiency of initial gene transfer and subsequent long-term persistence of gene expression. In this study, we examined long-term enhanced green fluorescent protein (eGFP) expression and vector genome persistence in the mouse liver after rAAV2/8-mediated gene transfer in early adulthood. Two intriguing findings emerged of considerable scientific and clinical interest. First, adult female and male mice showed distinctly different patterns of persistence of eGFP expression across the hepatic lobule after exhibiting similar patterns initially. Female mice retained a predominantly perivenous pattern of expression, whereas male mice underwent inversion of this pattern with preferential loss of perivenous expression and relative retention of periportal expression. Second, these changing patterns of expression correlated with sexually dimorphic patterns of genome persistence that appear linked both spatially and temporally to underlying hepatocellular proliferation. Observation of the equivalent phenomenon in man could have significant implications for the long-term therapeutic efficacy of rAAV-mediated gene transfer, particularly in the context of correction of liver functions showing metabolic zonation.

Use of Bioluminescent Imaging to Assay the Transplantation of Immortalized Human Fetal Hepatocytes into Mice

Noninvasive serial monitoring of the fate of transplanted cells would be invaluable to evaluate the potential therapeutic use of human hepatocyte transplantation. Therefore, we assessed the feasibility of bioluminescent imaging using double or triple fusion lentiviral vectors in a NOD-SCID mouse model transplanted with immortalized human fetal hepatocytes. Lentiviral vectors driven by the CMV promoter were constructed carrying reporter genes: firefly luciferase and green fluorescence protein with or without herpes simplex virus type 1 thymidine kinase. Human fetal hepatocytes immortalized by telomerase reconstitution (FH-hTERT) were successfully transduced with either of these fusion vectors. Two million stably transduced cells selected by fluorescence-activated cell sorting were injected into the spleens of NOD-SCID mice pretreated with methylcholanthrene and monocrotaline. The transplanted mice were serially imaged with a bioluminescence charged-coupled device camera after D-luciferin injection. Bioluminescence signal intensity was highest on day 3 (6.10 +/- 2.02 x 10(5) p/s/cm2/sr, mean +/- SEM), but decreased to 2.26 +/- 1.54 x 10(5) and 7.47 +/- 3.09 x 10(4) p/s/cm2/sr on day 7 and 10, respectively (p = 0.001). ELISA for human albumin in mice sera showed that levels were similar to those of control mice on day 2 (3.25 +/- 0.92 vs. 2.84 +/- 0.59 ng/ml, mean +/- SEM), peaked at 18.04 +/- 3.11 ng/ml on day 7, and decreased to 8.93 +/- 1.40 and 3.54 +/- 0.87 ng/ml on day 14 and 21, respectively (p = 0.02). Real-time quantitative RT-PCR showed gene expression levels of human albumin, alpha1-antitrypsin, and transferrin in mouse liver were 60.7 +/- 6.5%, 26.0 +/- 1.4%, and 156.8 +/- 62.4% of those of primary human adult hepatocytes, respectively, and immunohistochemistry revealed cells with human albumin and alpha1-antitrypsin expression in the mouse liver. In conclusion, our study demonstrated that bioluminescent imaging appears to be a sensitive, noninvasive modality for serial monitoring of transplanted hepatic stem cells.

Alpha-1 anti-trypsin and CD30 expression occur in parallel in activated T cells.

We have performed an immunohistochemical study of immunoblastic T cell lymphoma and enteropathy-associated T cell lymphoma for alpha-1 anti-trypsin and CD30. Cytoplasmic staining for alpha 1 anti-trypsin is present in the malignant cells in both types of T cell neoplasm which also express CD30, a marker of lymphoid activation. Peripheral blood T lymphocytes on stimulation with mitogen also show granular cytoplasmic expression of alpha 1 anti-trypsin. Time course studies show that this parallels the expression of CD30. Alpha 1 anti-trypsin expression appears therefore to be associated with activation in T cells. Further studies of sub-fractionated T lymphocytes in vitro suggest that the expression of alpha 1 anti-trypsin on activation is not restricted to an individual lymphocyte subset.

High Levels of Persistent Expression of α1-Antitrypsin Mediated by the Nonhuman Primate Serotype rh.10 Adeno-associated Virus Despite Preexisting Immunity to Common Human Adeno-associated Viruses

α1-Antitrypsin (α1AT) deficiency is a genetic disorder causing emphysema if serum α1AT levels are <570 μg/ml. We have shown that intrapleural administration of an AAV5α1AT vector yielded persistent therapeutic α1AT serum levels. Since anti-AAV2 and -AAV5 antibodies prevalent in humans may limit the use of these common serotypes in gene therapy, we screened 25 AAV vectors derived from humans and nonhuman primates for α1AT expression following intrapleural administration to mice. The rhesus AAVrh.10 serotype yielded the highest levels and was chosen for further study. Following intrapleural administration, 77% of total body transgene expression was in the chest wall, diaphragm, lung, and heart. Intrapleural administration of AAVrh.10α1AT provided long-term, therapeutic α1AT expression in mice, although higher doses were required to achieve therapeutic levels in female mice than in male mice. Intrapleural administration of AAVrh.10α1AT produced the same levels in AAV2/AAV5-preimmune and naive mice. In mice administered with AAV5α1AT and subsequently “boosted” with the AAVrh.10α1AT vector, serum levels were increased by 300%. These data indicate that AAVrh.10 is the most effective known AAV vector for intrapleural gene delivery and has the advantage of circumventing human immunity to AAV.

Conditional expression of α1-antitrypsin delivered by recombinant SV40 vectors protects lymphocytes against HIV

Constitutive expression of alpha(1)-antitrypsin (alpha(1)AT), a serine protease inhibitor, by a recombinant simian virus-40-based vector blocks both HIV gp160 and p55 processing, and so is a powerful inhibitor of HIV replication. To apply these findings more effectively in devising HIV therapies, we tested HIV LTR conditional promoter, to drive the expression of alpha(1)AT. SV[LTR](AT) was designed so that synthesis of human alpha(1)AT would be trans-activated by HIV infection. Cell lines and primary human lymphocytes were transduced with SV[LTR](AT) without selection and detectable toxicity. Responsiveness of alpha(1)AT expression to HIV Tat or HIV challenge was confirmed by Northern blotting, RT-PCR, cytofluorimetry and immunostaining. SV[LTR](AT)-transduced cells were protected from HIV-1(NL4-3) at a challenge dose of 0.04 MOI (T-cell lines) or 0.2 MOI (peripheral blood lymphocytes). Conditional expression of alpha(1)AT consistently protected T cells from HIV challenge as effectively as did constitutive expression. Combining the efficiency of rSV40 vectors with HIV-responsive expression of a highly effective anti-HIV therapeutic may be an effective approach to gene therapy of HIV replication.

Epstein-Barr virus/human vector provides high-level, long-term expression of alpha1-antitrypsin in mice.

We have constructed plasmid DNA vectors that contain Epstein-Barr virus (EBV) sequences and the human gene (SERPINA1) encoding alpha1-Antitrypsin (AAT). We demonstrate that a plasmid carrying the full SERPINA1 on a 19-kb genomic fragment and the EBV gene EBNA1 and its family of repeats binding sites undergoes efficient extrachromosomal replication in dividing mammalian tissue culture cells. Therefore, use of a whole genomic therapeutic gene to provide both replication and gene expression may be an effective gene therapy vector design, if the target cells are dividing. The efficacy of this same vector for expression of AAT in vivo in the nondividing cells of mouse liver was determined by hydrodynamic injection of naked plasmid DNA by means of the tail vein. A single injection of an EBV/genomic SERPINA1 vector provided >300 microg/ml of AAT, which approached normal plasma levels and persisted for the >9-month duration of the experiment. These data exceed most previously reported values, probably due to sequences in the genomic DNA that resist silencing of gene expression, possibly in combination with favorable effects on expression provided by the EBV sequences. These results demonstrate that plasmid DNA with the correct cis-acting sequences can provide in vivo long-term expression of protein at high levels that are therapeutically relevant for gene therapy.

Gene Expression of Proteases and Protease Inhibitors in the Human Ciliary Epithelium and ODM-2 Cells

Complementary DNAs (cDNAs), corresponding to the human proteinases cathepsins D and O and proteinase inhibitors α2-macroglobulin and PP5/TFPI-2, have recently been isolated and identified from a subtractive human ciliary body library. In the present study we determined: (i) their pattern of expression in the human eye; (ii) the ability of the ciliary body and/or ciliary epithelial cells to synthesize and secrete cathepsin D and α1-antitrypsin in vitro; and (iii) whether α1-antitrypsin expression in cultured ciliary epithelial cells is modulated by protein kinase C activation. Northern analysis demonstrated that the ciliary body expresses high levels of cathepsins D and O, α2-macroglobulin, α1-antitrypsin and PP5/TFPI-2 transcripts. Western blot analysis and immunoprecipitation experiments with cathepsin D and α1-antitrypsin antibodies indicated that metabolically labeled ciliary body explants and/or ciliary epithelial cells in vitro with35S-methionine, synthesize and secrete these proteins. Cultured nonpigmented ciliary epithelial ODM-2 cells, in response to phorbol-12-myristate 13-acetate (PMA), but not to the non-protein kinase C binding phorbol ester 4 α-phorbol didecanoate (PDBu), elicited up-regulation (up to 5-fold) of transcription, synthesis and secretion of α1-antitrypsin. These results provide in vitro evidence that the ciliary epithelium synthesizes and secretes a selective group of proteinases and proteinase inhibitors detected also in aqueous humor. The expression of at least of one of the proteinase inhibitors, α1-antitrypsin, can be modulated in response to phorbol ester.

Regulation of the alpha 1-antitrypsin gene and a disease-associated mutation in a related enhancer sequence.

Ten years ago a search was initiated for DNA variation in the alpha-1-antitrypsin gene (alpha 1-AT) to determine whether there were mutations more commonly associated with patients who had chronic obstructive airways disease (COAD) than with healthy individuals. Using the conventional approach of Southern blotting and searching for restriction fragment length polymorphisms, we identified a potentially useful polymorphism that resulted in the loss of a recognition site for the restriction enzyme, Taq I. The polymorphism occurred in about 17% of patients with COAD and about 5% of the general population (p = 0.0016). The normal sequence in the 3' flanking region of the alpha 1-antitrypsin gene had to be characterized, as it was not known. On the basis of homology, a number of closely clustered sequence motifs demonstrating the characteristics of an enhancer were identified that would potentially increase the transcription and expression of alpha 1-antitrypsin. The normal Taq I sequence occurred in a motif that demonstrated homology to a DNA sequence for octamer transcription factors. The mutation was characterized by in vitro amplification of the region and direct sequencing as a G to A transition (Taq I site TCGA < TCAA). Specific binding of nuclear proteins by gel-shift analysis and DNase I footprinting and increased in vivo transcriptional activity were demonstrated by transfection of mammalian cells containing DNA fragments corresponding to the region of interest. In contrast, the mutant sequence demonstrated loss of binding to nuclear proteins and reduced transcriptional activity. The latter finding was not confined to tissues known to express alpha 1-antitrypsin.(ABSTRACT TRUNCATED AT 250 WORDS)