Differential expression of carbonic anhydrase isoenzymes in various types of anemia

MALDI-TOF-MS for Rapid Screening and Typing of β-Globin Variant and β-Thalassemia through Direct Measurements of Intact Globin Chains

BACKGROUND

Traditional phenotype-based screening for β-globin variant and β-thalassemia using hematological parameters is time-consuming with low-resolution detection. Development of a MALDI-TOF-MS assay using alternative markers is needed.

METHODS

We constructed a MALDI-TOF-MS-based approach for identifying various β-globin disorders and classifying thalassemia major (TM) and thalassemia intermedia (TI) patients using 901 training samples with known HBB/HBA genotypes. We then validated the accuracy of population screening and clinical classification in 2 separate cohorts consisting of 16 172 participants and 201 β-thalassemia patients. Traditional methods were used as controls. Genetic tests were considered the gold standard for testing positive specimens.

RESULTS

We established a prediction model for identifying different forms of β-globin disorders in a single MALDI-TOF-MS test based on δ- to β-globin, γ- to α-globin, γ- to β-globin ratios, and/or the abnormal globin-chain patterns. Our validation study yielded comparable results of clinical specificity (99.89% vs 99.71%), and accuracy (99.78% vs 99.16%) between the new assay and traditional methods but higher clinical sensitivity for the new method (97.52% vs 88.01%). The new assay identified 22 additional abnormal hemoglobins in 69 individuals including 9 novel ones, and accurately screened for 9 carriers of deletional hereditary persistence of fetal hemoglobin or δβ-thalassemia. TM and TI were well classified in 178 samples out of 201 β-thalassemia patients.

CONCLUSIONS

MALDI-TOF-MS is a highly accurate, predictive tool that could be suitable for large-scale screening and clinical classification of β-globin disorders.

Experimental Approaches to Identify Selective Picomolar Inhibitors for Carbonic Anhydrase IX

BACKGROUND

Carbonic anhydrases (CAs) regulate pH homeostasis via the reversible hydration of CO₂, thereby emerging as essential enzymes for many vital functions. Among 12 catalytically active CA isoforms in humans, CA IX has become a relevant therapeutic target because of its role in cancer progression. Only two CA IX inhibitors have entered clinical trials, mostly due to low affinity and selectivity properties.

OBJECTIVE

The current review presents the design, development, and identification of the selective nano- to picomolar CA IX inhibitors VD11-4-2, VR16-09, and VD12-09.

METHODS AND RESULTS

Compounds were selected from our database, composed of over 400 benzensulfonamides, synthesized at our laboratory, and tested for their binding to 12 human CAs. Here we discuss the CA CO₂ hydratase activity/inhibition assay and several biophysical techniques, such as fluorescent thermal shift assay and isothermal titration calorimetry, highlighting their contribution to the analysis of compound affinity and structure- activity relationships. To obtain sufficient amounts of recombinant CAs for inhibitor screening, several gene cloning and protein purification strategies are presented, including site-directed CA mutants, heterologous CAs from Xenopus oocytes, and native endogenous CAs. The cancer cell-based methods, such as clonogenicity, extracellular acidification, and mass spectrometric gas-analysis are reviewed, confirming nanomolar activities of lead inhibitors in intact cancer cells.

CONCLUSIONS

Novel CA IX inhibitors are promising derivatives for in vivo explorations. Furthermore, the simultaneous targeting of several proteins involved in proton flux upon tumor acidosis and the disruption of transport metabolons might improve cancer management.

Carbonic Anhydrase in Pacific Abalone Haliotis discus hannai: Characterization, Expression, and Role in Biomineralization

Carbonic anhydrases (CAs) are universal zinc ion containing metalloenzymes that play a pivotal role in various physiological processes. In this study, a CA I (designated as Hdh CA I) was isolated and characterized from the mantle tissue of Pacific abalone, Haliotis discus hannai. The full-length cDNA sequence of Hdh CA I was 1,417-bp in length, encoding a protein of 337 amino acids with molecular weight of 37.58 kDa. Hdh CA I sequence possessed a putative signal peptide of 22 amino acids and a CA catalytic function domain. The predicted protein shared 94 and 78% sequence identities with Haliotis gigantea and Haliotis tuberculata CA I, respectively. Results of phylogenetic analysis indicated that Hdh CA I was evolutionarily close to CA I of H. gigantea and H. tuberculata with high bootstrap values. Significantly higher levels of Hdh CA I mRNA transcript were found in mantle than other examined tissues. In situ hybridization results showed strong hybridization signals in epithelial cells of the dorsal mantle pallial, an area known to synthesize and secrete proteins responsible for the nacreous layer formation of shell. This is the first study on Hdh CA I in H. discus hannai and the results may contribute to further study its physiological functions in shell biomineralization of abalone.

Identification and Validation of Carbonic Anhydrase II as the First Target of the Anti-Inflammatory Drug Actarit

Background and purpose: Identifying the macromolecular targets of drug molecules is a fundamental aspect of drug discovery and pharmacology. Several drugs remain without known targets (orphan) despite large-scale in silico and in vitro target prediction efforts. Ligand-centric chemical-similarity-based methods for in silico target prediction have been found to be particularly powerful, but the question remains of whether they are able to discover targets for target-orphan drugs. Experimental Approach: We used one of these in silico methods to carry out a target prediction analysis for two orphan drugs: actarit and malotilate. The top target predicted for each drug was carbonic anhydrase II (CAII). Each drug was therefore quantitatively evaluated for CAII inhibition to validate these two prospective predictions. Key Results: Actarit showed in vitro concentration-dependent inhibition of CAII activity with submicromolar potency (IC₅₀ = 422 nM) whilst no consistent inhibition was observed for malotilate. Among the other 25 targets predicted for actarit, RORγ (RAR-related orphan receptor-gamma) is promising in that it is strongly related to actarit’s indication, rheumatoid arthritis (RA). Conclusion and Implications: This study is a proof-of-concept of the utility of MolTarPred for the fast and cost-effective identification of targets of orphan drugs. Furthermore, the mechanism of action of actarit as an anti-RA agent can now be re-examined from a CAII-inhibitor perspective, given existing relationships between this target and RA. Moreover, the confirmed CAII-actarit association supports investigating the repositioning of actarit on other CAII-linked indications (e.g., hypertension, epilepsy, migraine, anemia and bone, eye and cardiac disorders).

Carbonic Anhydrase Sensitivity to Pesticides: Perspectives for Biomarker Development

Carbonic anhydrase (CA) is a widespread metalloenzyme playing a pivotal role in several physiological processes. Many studies have demonstrated the in vitro and in vivo sensitivity of CA to the exposure to several classes of pesticides in both humans and wildlife. This review aims to analyze and to discuss the literature available in this field, providing a comprehensive view useful to foresee perspectives for the development of novel CA-based pesticide biomarkers. The analysis of the available data highlighted the ability of several pesticide molecules to interact directly with the enzyme in humans and wildlife and to inhibit CA activity in vitro and in vivo, with possible alterations of key physiological functions. The analysis disclosed key areas of further research and, at the same time, identified some perspectives for the development of novel CA-based sensitive biomarkers to pesticide exposure, suitable to be used in several fields from human biomonitoring in occupational and environmental medicine to environmental monitoring on non-target species.

The Presence of Serum TgAb Suggests Lower Risks for Glucose and Lipid Metabolic Disorders in Euthyroid General Population From a National Survey

Purpose: The expressions of antibodies against thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) are very common in the sera of patients with autoimmune thyroid diseases (AITD). The relationship between thyroid autoantibodies and the occurrence of glucose and lipid metabolic disorders remains unclear. This study was performed to investigate the correlation between the presence of serum TPOAb/TgAb and those metabolic disorders in euthyroid general population. Methods: The data of this study were derived from the Thyroid Disease, Iodine status, and Diabetes National epidemiological (TIDE) survey from all 31 provinces of mainland China. A total of 17,964 euthyroid subjects including 5,802 males (4,000 with TPOAb^-TgAb^- and 1,802 with TPOAb⁺/TgAb⁺) and 12,162 females (8,000 with TPOAb^-TgAb^- and 4,162 with TPOAb⁺/TgAb⁺) were enrolled in this study. The blood glucose and lipid levels were compared between individuals with TPOAb^-TgAb^- and those with TPOAb⁺TgAb^-, TPOAb^-TgAb⁺, TPOAb⁺TgAb⁺. Results: Both fasting blood glucose (FBG) concentration and the proportion of individuals with impaired FBG (IFG) showed the decreased trends in TPOAb^-TgAb⁺ males as compared with TPOAb^-TgAb^- men. There were significantly lower FBG and higher HDL-C levels as well as tendencies toward decreased incidences of IGT and hypertriglyceridemia in TPOAb^-TgAb⁺ females when compared with TPOAb^-TgAb^- women. Binary logistic regression analysis further showed that serum TgAb single positivity in males was an independent protective factor for IFG with an OR of 0.691 (95% CI, 0.503-0.949). For females, serum TgAb single positivity was an independent protective factor for hypertriglyceridemia with an OR of 0.859 (95% CI, 0.748-0.987). Trend test showed that with the increase of serum TgAb level, there were significant decreases in the prevalence of IFG among the men with TSH ≤ 2.5 mIU/L and that of hypertriglyceridemia in the women, especially among non-obese females. Conclusion: Serum TgAb single positivity may imply a reduced risk of IFG in euthyroid men and that of hypertriglyceridemia in euthyroid women. The mechanisms for the independent protective roles of TgAb await further investigation.

A network pharmacology approach to investigate the blood enriching mechanism of Danggui buxue Decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Danggui buxue Decoction (DBD) has been frequently used to treat with blood deficiency, which consisted of Danggui (DG) and Huangqi (HQ) at a ratio of 1:5. Accumulating evidence showed that blood deficiency in traditional Chinese medicine (TCM) was similar to anemia in modern medicine.

AIM OF THE STUDY

The purpose of this study was to explore its therapeutic mechanism of with network pharmacology approach.

MATERIALS AND METHODS

We explored the chemical compounds of DBD and used compound ADME screening to identify the potential compounds. Targets for the therapeutic actions of DBD were obtained from the PharmMapper, Swiss, SEA and STITCH. GO analysis and pathway enrichment analysis was performed using the DAVID webserver. Cytoscape was used to visualize the compound-target-pathway network for DBD. The pharmacodynamics and crucial targets were also validated.

RESULTS

Thirty-six potential active components in DBD and 49 targets which the active components acted on were identified. 47 KEGG pathways which DBD acted on were also come to light. And then, according to KEGG pathway annotation analysis, only 16 pathways seemed to be related to the blood nourishing effect of DBD, such as PI3K-AKT pathway, and so on. Only 32 targets participated in these 16 pathways and they were acted on by 29 of the 36 active compounds. Whole pharmacodynamic experiments showed that DBD had significant effects to blood loss rats. Furthermore, DBD could promote the up-regulation of hematopoietic and immune related targets and the down-regulation of inflammatory related targets. Significantly, with the results of effective rate, molecular docking and experimental validation, we predicted astragaloside IV in HQ, senkyunolide A and senkyunolide K in DG might be the major contributing compounds to DBD's blood enriching effect.

CONCLUSION

In this study, a systematical network pharmacology approach was built. Our results provided a basis for the future study of senkyunolide A and senkyunolide K as the blood enriching compounds in DBD. Furthermore, combined network pharmacology with validation experimental results, the nourishing blood effect of DBD might be manifested by the dual mechanism of enhancing immunity and promoting hematopoiesis.

Transcriptome Profiling Analysis Reveals the Potential Mechanisms of Three Bioactive Ingredients of Fufang E'jiao Jiang During Chemotherapy-Induced Myelosuppression in Mice

Although multiple bioactive components have been identified in Fufang E’jiao Jiang (FEJ), their hematopoietic effects and molecular mode of action in vivo are still not fully understood. In the current study, we analyzed the effects of martynoside, R-notoginsenoside R2 (R2), and 20S-ginsenoside Rg2 (Rg2) in a 5-fluorouracil-induced myelosuppression mouse model. Bone marrow nucleated cells (BMNCs) counts, hematopoietic progenitor cell colony-forming unit (CFU) assay, as well as flow cytometry analysis of Lin^-/c-kit⁺/Sca-1⁺ hematopoietic stem cell (HSC) population were conducted, and bone marrow cells were subjected to RNA sequencing. The transcriptome data were processed based on the differentially expressed genes. The results of the analysis show that each of the three compounds stimulates BMNCs and HSC growth, as well as burst-forming unit-erythroid and colony-forming unit granulocyte-monocyte colony expansion. The most relevant transcriptional changes appeared to be involved in regulation of hematopoietic cell lineage, NF-κB and TNF-α signaling, inhibition of inflammation, and acceleration of hematopoietic cell recovery. Notably, the individual compounds shared similar but specified transcriptome profiles. Taken together, the hematopoietic effects for the three tested compounds of FEJ are confirmed in this myelosuppression mouse model. The transcriptome maps of these effects provide valuable information concerning their underlying mechanisms and provide a framework for the continued study of the complex mode of action of FEJ.

Carbonic Anhydrases: Role in pH Control and Cancer

The pH of the tumor microenvironment drives the metastatic phenotype and chemotherapeutic resistance of tumors. Understanding the mechanisms underlying this pH-dependent phenomenon will lead to improved drug delivery and allow the identification of new therapeutic targets. This includes an understanding of the role pH plays in primary tumor cells, and the regulatory factors that permit cancer cells to thrive. Over the last decade, carbonic anhydrases (CAs) have been shown to be important mediators of tumor cell pH by modulating the bicarbonate and proton concentrations for cell survival and proliferation. This has prompted an effort to inhibit specific CA isoforms, as an anti-cancer therapeutic strategy. Of the 12 active CA isoforms, two, CA IX and XII, have been considered anti-cancer targets. However, other CA isoforms also show similar activity and tissue distribution in cancers and have not been considered as therapeutic targets for cancer treatment. In this review, we consider all the CA isoforms and their possible role in tumors and their potential as targets for cancer therapy.

Serum Carbonic Anhydrase 1 is a Biomarker for Diagnosis of Human Schistosoma mansoni Infection

AbstractSchistosoma mansoni is a major public health threat in many parts of the world. The current diagnostic tests for schistosomiasis are suboptimal, particularly early in infection, when the parasite burden is low and with reinfection after treatment. We sought to identify novel biomarkers of active infection by studying serum proteins in a mouse model of schistosomiasis followed by confirmation in chronically infected patients. Acute (6 weeks) and chronic (12 weeks) sera from S. mansoni-infected C57Bl/6 mice as well as sera from chronically infected patients were assessed using two proteomic platforms: surface-enhanced, laser desorption and ionization, time-of-flight mass spectrometry and Velos Orbitrap mass spectrometry. Several candidate biomarkers were further evaluated by Western blot and/or enzyme-linked immunosorbent assay (ELISA). Among the most promising was carbonic anhydrase 1 (CA1), a host protein found primarily in red blood cells and enterocytes that proved to be a negative biomarker for schistosomiasis in both mouse and human samples. Reduced serum CA-1 levels were confirmed by both Western blot (murine and human: both P < 0.001) and ELISA (human: P < 0.01). Western blots of serial mouse sera revealed a progressive reduction in serum CA1 levels over the 12-week infection period. CA1 is a promising negative serum biomarker for the diagnosis of S. mansoni infection.

Proteochemometric Modeling of the Interaction Space of Carbonic Anhydrase and its Inhibitors: An Assessment of Structure-based and Sequence-based Descriptors

Due to its physiological and clinical roles, carbonic anhydrase (CA) is one of the most interesting case studies. There are different classes of CAinhibitors including sulfonamides, polyamines, coumarins and dithiocarbamates (DTCs). However, many of them hardly act as a selective inhibitor against a specific isoform. Therefore, finding highly selective inhibitors for different isoforms of CA is still an ongoing project. Proteochemometrics modeling (PCM) is able to model the bioactivity of multiple compounds against different isoforms of a protein. Therefore, it would be extremely applicable when investigating the selectivity of different ligands towards different receptors. Given the facts, we applied PCM to investigate the interaction space and structural properties that lead to the selective inhibition of CA isoforms by some dithiocarbamates. Our models have provided interesting structural information that can be considered to design compounds capable of inhibiting different isoforms of CA in an improved selective manner. Validity and predictivity of the models were confirmed by both internal and external validation methods; while Y-scrambling approach was applied to assess the robustness of the models. To prove the reliability and the applicability of our findings, we showed how ligands-receptors selectivity can be affected by removing any of these critical findings from the modeling process.

Biological Systems of Vitamin K: A Plasma Nutriproteomics Study of Subclinical Vitamin K Deficiency in 500 Nepalese Children

Vitamin K (VK) is a fat-soluble vitamin whose deficiency disrupts coagulation and may disturb bone and cardiovascular health. However, the scale and systems affected by VK deficiency in pediatric populations remains unclear. We conducted a study of the plasma proteome of 500 Nepalese children 6–8 years of age (male/female ratio = 0.99) to identify proteins associated with VK status. We measured the concentrations of plasma lipids and protein induced by VK absence-II (PIVKA-II) and correlated relative abundance of proteins quantified by mass spectrometry with PIVKA-II. VK deficiency (PIVKA-II >2 μg/L) was associated with a higher abundance of low-density lipoproteins, total cholesterol, and triglyceride concentrations (p < 0.01). Among 978 proteins observed in >10% of the children, five proteins were associated with PIVKA-II and seven proteins were differentially abundant between VK deficient versus sufficient children, including coagulation factor-II, hemoglobin, and vascular endothelial cadherin, passing a false discovery rate (FDR) threshold of 10% (q < 0.10). Among 27 proteins associated with PIVKA-II or VK deficiency at a less stringent FDR (q < 0.20), a network comprised of hemoglobin subunits and erythrocyte anti-oxidative enzymes were highly and positively correlated each other (all r > 0.7). Untargeted proteomics offers a novel systems approach to elucidating biological processes of coagulation, vascularization, and erythrocyte oxidative stress related to VK status. The results may help elucidate subclinical metabolic disturbances related to VK deficiency in populations.

Characterization of carbonic anhydrase XIII in the erythrocytes of the Burmese python, Python molurus bivittatus

Carbonic anhydrase (CA) is one of the most abundant proteins found in vertebrate erythrocytes with the majority of species expressing a low activity CA I and high activity CA II. However, several phylogenetic gaps remain in our understanding of the expansion of cytoplasmic CA in vertebrate erythrocytes. In particular, very little is known about isoforms from reptiles. The current study sought to characterize the erythrocyte isoforms from two squamate species, Python molurus and Nerodia rhombifer, which was combined with information from recent genome projects to address this important phylogenetic gap. Obtained sequences grouped closely with CA XIII in phylogenetic analyses. CA II mRNA transcripts were also found in erythrocytes, but found at less than half the levels of CA XIII. Structural analysis suggested similar biochemical activity as the respective mammalian isoforms, with CA XIII being a low activity isoform. Biochemical characterization verified that the majority of CA activity in the erythrocytes was due to a high activity CA II-like isoform; however, titration with copper supported the presence of two CA pools. The CA II-like pool accounted for 90 % of the total activity. To assess potential disparate roles of these isoforms a feeding stress was used to up-regulate CO2 excretion pathways. Significant up-regulation of CA II and the anion exchanger was observed; CA XIII was strongly down-regulated. While these results do not provide insight into the role of CA XIII in the erythrocytes, they do suggest that the presence of two isoforms is not simply a case of physiological redundancy.

Advances in Anti-Cancer Drug Development Targeting Carbonic Anhydrase IX and XII

The microenvironment within a solid tumor is heterogeneous with regions being both acidic and hypoxic. As a result of this, cancer cells upregulate genes that allow survival in such environments. Some of these genes are pH regulatory factors, including carbonic anhydrase IX (CA IX) and in some cases XII (CA XII). CA IX helps to maintain normal cytoplasmic pH (pHi) while simultaneously contributing to the extracellular pH (pHe). CA XII is also thought to be responsible for stabilizing pHe at physiological conditions. Extracellular acidification of the tumor microenvironment promotes local invasion and metastasis while decreasing the effectiveness of adjuvant therapies, thus contributing to poor cancer clinical outcomes. In this review, we describe the properties of CA IX and CA XII that substantiate their potential use as anticancer targets. We also discuss the current status of CA isoform-selective inhibitor development and patents of CA IX/XII targeted inhibitors that show potential for treating aggressive tumors. Some of the recently published patents discussed include sulfonamide-based small molecule inhibitors including derivatives of boron cluster compounds; metal complexes of poly(carboxyl)amine-containing ligands; nitroi-midazole-, ureidosulfonamide-, and coumarin-based compounds; as well as G250 and A610 monoclonal antibodies for cancer treatment.

Physiological functions of the alpha class of carbonic anhydrases

Carbonic anhydrases are ubiquitous enzymes that catalyze the reversible hydration of carbon dioxide. These enzymes are of ancient origin as they are found in the deepest of branches of the evolutionary tree. Of the five different classes of carbonic anhydrases, the alpha class has perhaps received the most attention because of its role in human pathology. This review focuses on the physiological function of this class of carbonic anhydrases organized by their cellular location.

Reduction of CAII Expression in Gastric Cancer: Correlation with Invasion and Metastasis

OBJECTIVE

Human carbonic anhydrases II (CAII) gene plays an important role in different cancer. However, its relevance to gastric cancer (GC) remains unclear. In the present study, we aimed to investigate the expression of CAII in GC and explore its correlation with some clinicopathologic characteristics of GC.

METHODS

The expression of CAII in 20 specimens of normal gastric mucosa, 38 specimens of intraepithelial neoplasia and 112 specimens of gastric carcinoma were detected by immunohistochemical techniques. Survival in GC with CAII expression was studied.

RESULTS

The positive rate of CAII protein in normal gastric mucosa was significantly higher than that in intraepithelial neoplasia and gastric carcinoma (100% vs. 63.16% and 28.57%, P<0.001). The positive rate of CAII protein was significantly higher in gastric carcinoma at early stages than that at advanced stages (70.0% vs. 19.57%, P<0.001). The positive rate of CAII protein was significantly lower in gastric carcinoma with lymph node metastases than that without lymph node metastases (10.81% vs. 37.33%, P<0.05). Furthermore, the positive rate of CAII protein was significantly lower in poorly-differentiated gastric carcinoma than in moderately- or well-differentiated gastric carcinoma (15.94% vs. 31.03% or 60.00%, P<0.05). Moreover, CAII expression was not related with sex, age and tumor size. The patients with CAII-positive tumors showed a better survival rate than those with CAII-negative tumors (P=0.024, log-rank test).

CONCLUSION

CAII expression was related with stages and lymph node metastases in gastric carcinoma. The reduction of CAII expression in GC might promote tumor cell motility and contribute to tumor growth and metastasis.

Down regulation of CAII is associated with tumor differentiation and poor prognosis in patients with pancreatic cancer

BACKGROUND AND OBJECTIVES

Altered expression of carbonic anhydrase (CA)I and II associated with human carcinogenesis. But there was no definite study investigating their expression for clinical significance in pancreatic cancer and effect of the CA inhibitor acetazolamide (AZ) on regulation biological behavior of pancreatic cancer cells.

METHODS

Immunohistochemistry, immunofluorescence, immunoblot, and qRT-PCR were used to detect CAI, II, and p53 expression. Tumor cell viability, apoptosis, and invasion assays were used to investigate the effect of AZ on pancreatic cancer cells.

RESULTS

Expression of CAI and p53 was increased in pancreatic cancer than that in paired non-cancerous tissues (P = 0.021; P = 0.007), whereas CAII was down-regulated in pancreatic cancer (P = 0.001). CAI overexpression was associated with tumor differentiation and negatively with vascular invasion (P = 0.015 and P = 0.018, respectively), while overexpression of CAII was associated with tumor differentiation (P = 0.017) and a better prognosis of pancreatic cancer patients (P = 0.017), and was an independent prognostic indicator (P = 0.011). p53 overexpression was related with lymph node metastasis (P = 0.032) and TNM stage (P = 0.016). Treatment with AZ inhibited tumor cell validity, invasion, and induced apoptosis in some of six pancreatic cancer cells.

CONCLUSION

This study suggests the clinical significance of CAI, CAII and p53 expression in pancreatic cancer and provides evidence for AZ as a potential target for controlling pancreatic cancer.

Heterogeneity of F cells in β-thalassemia

BACKGROUND

Fetal hemoglobin (HbF), which is largely replaced after birth by the adult Hb, is concentrated in a few "F cells." Their number significantly increases in certain physiologic and clinical situations, including in β-thalassemia (β-thal). Their quantification is used to detect fetal-maternal hemorrhage (FMH), where fetal cells enter the maternal circulation. We were confronted with a pregnant woman with β-thal who was suspected to have FMH. To establish the usefulness of a flow cytometric procedure to differentiate between fetal cells and the maternal F cells, we screened adult β-thal patients.

STUDY DESIGN AND METHODS

Blood samples were simultaneously stained with fluorescent antibodies to HbF and to carbonic anhydrase (CA) isotype II, which is specific to adult red blood cells (RBCs).

RESULTS

A heterogeneous distribution of RBCs with respect to HbF and CA expression was observed: adult non-F cells (CA+HbF-) and F cells (CA+HbF+/HbF++) as well as F cells with characteristics of fetal cells (CA-HbF++).

CONCLUSIONS

The presence of CA-HbF++ RBCs in nonpregnant women, and even men, with thal indicates that the CA/HbF method is inappropriate for detection of FMH. The coexistence of F cells carrying fetal or adult markers suggests that they originate from two types of stem cell, adult and fetal, lineages. Normally, the fetal lineage is insignificant, but in β-thal, as HbF-containing RBCs have a selective advantage, the "fetal" lineage gains significance.

Structure, function and applications of carbonic anhydrase isozymes

The carbonic anhydrases enzymes (CAs, EC 4.2.1.1) are zinc containing metalloproteins, which efficiently catalyse the reversible conversion of carbon dioxide to bicarbonate and release proton. These enzymes are essentially important for biological system and play several important physiological and patho-physiological functions. There are 16 different alpha-carbonic anhydrase isoforms studied, differing widely in their cellular localization and biophysical properties. The catalytic domains of all CAs possess a conserved tertiary structure fold, with predominately β-strands. We performed an extensive analysis of all 16 mammalian CAs for its structure and function in order to establish a structure-function relationship. CAs have been a potential therapeutic target for many diseases. Sulfonamides are considered as a strong and specific inhibitor of CA, and are being used as diuretics, anti-glaucoma, anti-epileptic, anti-ulcer agents. Currently CA inhibitors are widely used as a drug for the treatment of neurological disorders, anti-glaucoma drugs, anti-cancer, or anti-obesity agents. Here we tried to emphasize how CAs can be used for drug discovery, design and screening. Furthermore, we discussed the role of CA in carbon capture, carbon sensor and metabolon. We hope this review provide many useful information on structure, function, mechanism, and applications of CAs in various discipline.

Enhanced sensitivity to hydrogen peroxide-induced apoptosis in Evi1 transformed Rat1 fibroblasts due to repression of carbonic anhydrase III

EVI1 is a nuclear zinc finger protein essential to normal development, which participates in acute myeloid leukaemia progression and transforms Rat1 fibroblasts. In this study we show that enforced expression of Evi1 in Rat1 fibroblasts protects from paclitaxel-induced apoptosis, consistent with previously published studies. Surprisingly, however, these cells show increased sensitivity to hydrogen peroxide (H(2)O(2))-induced apoptosis, demonstrated by elevated caspase 3 catalytic activity. This effect is caused by a reduction in carbonic anhydrase III (caIII) production. caIII transcripts are repressed by 92-97% by Evi1 expression, accompanied by a similar reduction in caIII protein. Reporter assays with the rat caIII gene promoter show repressed activity, demonstrating that Evi1 either directly or indirectly modulates transcription of this gene in Rat1 cells. Targeted knockdown of caIII alone, with Dicer-substrate short inhibitory RNAs, also increases the sensitivity of Rat1 fibroblasts to H(2)O(2), which occurs in the absence of any other changes mediated by Evi1 expression. Enforced expression of caIII in Evi1-expressing Rat1 cells reverts the phenotype, restoring H(2)O(2) resistance. Together these data show that Evi1 represses transcription of caIII gene expression, leading to increased sensitivity to H(2)O(2)-induced apoptosis in Rat1 cells and might suggest the basis for the development of a novel therapeutic strategy for the treatment of leukaemias and solid tumours where EVI1 is overexpressed.

HPLC-CHIP coupled to a triple quadrupole mass spectrometer for carbonic anhydrase II quantification in human serum

A method for carbonic anhydrase II (CA II) absolute quantification in human serum is presented. This method is based on high-performance liquid chromatography (HPLC)-Chip microfluidic device incorporating a nanoelectrospray source interfaced to a triple quadrupole mass spectrometer. The fraction containing CA II was isolated by preparative reversed-phase HPLC, and peptides obtained from the tryptic digest of the protein mixture were separated by the HPLC-Chip system. The multiple-reaction monitoring acquisition mode of a selected suitable CA II peptide and peptide internal standard allowed the selective and sensitive determination of a CA II. Absolute recovery of the method was 52 +/- 12%, while analytical recovery was 81 +/- 10%. For the eight samples analyzed, the matrix effect was found to be only -14 +/- 6%. A comparison among three regression lines type which were obtained by external calibration, matrix-matched calibration, and standard addition method, respectively, demonstrated that the first one is adequate in obtaining good accuracy and precision. Method quantification limit for CA II in serum was estimated to be 2 fmol/mL. CA II mean concentration in sera from eight healthy subjects was found to be 56 pmol/mL (relative standard deviation 24%).

Differential expression of glutathione-S-transferase isoenzymes in various types of anemia in Taiwan

BACKGROUND

Published reports concerning the expression of GST in various anemias including aplastic, hemolytic, iron deficiency and thalassemia anemia has been insufficient. We improved the conventional GST assay by incorporating a chloroform treatment to remove the interference of hemoglobin and evaluated the altered expression of GSTs in various anemias in Taiwan.

METHODS

We incorporated a chloroform treatment to eliminate the interference of hemoglobin. Erythrocyte total GST and isoenzymes activities from 35 control subjects and 125 subjects of various anemias, including aplastic, hemolytic, iron deficiency and thalassemia anemias were measured spectrophotometrically.

RESULTS

Chloroform treatment did not significantly affect GST activities in erythrocytes of control subjects while the activities of erythrocyte total GST and alpha-GST were significantly increased in all anemic patients (P<0.001). The expression of mu-GST was significantly decreased, although at a less extent, in cases of aplastic, iron deficiency and thalassemia anemia (P<0.05), but pi-GST was not physiologically different in various types of anemia.

CONCLUSION

The determination of changes in erythrocyte GST activity is a promising indicator of oxidative stress conditions that occur in various types of anemia. Measurement of GST activity might be useful for the evaluation of prophylactic treatment in trials of antioxidant strategies.