Platelets do not express the oxidized or reduced forms of tissue factor

BACKGROUND

Expression of tissue factor (TF) antigen and activity in platelets is controversial and dependent upon the laboratory and reagents used. Two forms of TF were described: an oxidized functional form and a reduced nonfunctional form that is converted to the active form through the formation of an allosteric disulfide. This study tests the hypothesis that the discrepancies regarding platelet TF expression are due to differential expression of the two forms.

METHODS

Specific reagents that recognize both oxidized and reduced TF were used in flow cytometry of unactivated and activated platelets and western blotting of whole platelet lysates. TF-dependent activity measurements were used to confirm the results.

RESULTS

Western blotting analyses of placental TF demonstrated that, in contrast to anti-TF#5, which is directed against the oxidized form of TF, a sheep anti-human TF polyclonal antibody recognizes both the reduced and oxidized forms. Flow cytometric analyses demonstrated that the sheep antibody did not react with the surface of unactivated platelets or platelets activated with thrombin receptor agonist peptide, PAR-1. This observation was confirmed using biotinylated active site-blocked factor (F)VIIa: no binding was observed. Likewise, neither form of TF was detected by western blotting of whole platelet lysates with sheep anti-hTF. Consistent with these observations, no FXa or FIXa generation by FVIIa was detected at the surface of these platelets. Similarly, no TF-related activity was observed in whole blood using thromboelastography.

CONCLUSION AND SIGNIFICANCE

Platelets from healthy donors do not express either oxidized (functional) or reduced (nonfunctional) forms of TF.

N-terminus regulation of VMAT2 mediates methamphetamine-stimulated efflux

The 20 amino acid (AA) N-terminus of the vesicular monoamine transporter 2 (VMAT2) was examined as a regulator of VMAT2 function. Removal of the first 16 or 19 AAs of the N-terminus resulted in a molecule with reduced ability to sequester [(3)H]-5HT. A glutathione-S-transferase-construct of the N-terminus underwent phosphorylation in the presence of PKC at serines 15 and 18. These putative phosphorylation sites were examined for effects on function. Phospho-mimetic substitution of serines 15 and 18 with aspartate in the full-length VMAT2 resulted in reduced [(3)H]-5HT sequestration and reduced methamphetamine (METH)-stimulated efflux of preloaded [(3)H]-5HT. In contrast, mutation of serines 15 and 18 to alanines maintained intact net substrate sequestration but eliminated METH-stimulated efflux of pre-accumulated [(3)H]-5HT. In summary, these data suggest a model in which the VMAT2 N-terminus regulates monoamine sequestration.

Three novel homozygous mutations in the GNPTG gene that cause mucolipidosis type III gamma

BACKGROUND

Mucolipidosis type III gamma (MLIII gamma) is an autosomal recessive disease caused by a mutation in the GNPTG gene, which encodes the γ subunit of the N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase). This protein plays a key role in the transport of lysosomal hydrolases to the lysosome.

METHODS

Three Chinese children with typical skeletal abnormalities of MLIII were identified, who were from unrelated consanguineous families. After obtaining informed consent, genomic DNA was isolated from the patients and their parents. Direct sequencing of the GNPTG and GNPTAB genes was performed using standard PCR reactions.

RESULTS

The three probands showed clinical features typical of MLIII gamma, such as joint stiffness and vertebral scoliosis without coarsened facial features. Mutation analysis of the GNPTG gene showed that three novel mutations were identified, two in exon seven [c.425G>A (p.Cys142Val)] and [c.515dupC (p.His172Profs27X)], and one in exon eight [c.609+1G>C]. Their parents were determined to be heterozygous carriers when compared to the reference sequence in GenBank on NCBI.

CONCLUSIONS

Mutation of the GNPTG gene is the cause of MLIII gamma in our patients. Our findings expand the mutation spectrum of the GNPTG gene and extend the knowledge of the phenotype-genotype correlation of the disease.

ALG1-CDG: a new case with early fatal outcome

Congenital disorders of glycosylation (CDG) are a growing group of inherited metabolic disorders where enzymatic defects in the formation or processing of glycolipids and/or glycoproteins lead to variety of different diseases. The deficiency of GDP-Man:GlcNAc2-PP-dolichol mannosyltransferase, encoded by the human ortholog of ALG1 from yeast, is known as ALG1-CDG (CDG-Ik). The phenotypical, molecular and biochemical analysis of a severely affected ALG1-CDG patient is the focus of this paper. The patient's main symptoms were feeding problems and diarrhea, profound hypoproteinemia with massive ascites, muscular hypertonia, seizures refractory to treatment, recurrent episodes of apnoea, cardiac and hepatic involvement and coagulation anomalies. Compound heterozygosity for the mutations c.1145T>C (M382T) and c.1312C>T (R438W) was detected in the patient's ALG1-coding sequence. In contrast to a previously reported speculation on R438W we confirmed both mutations as disease-causing in ALG1-CDG.

A Txnrd1-dependent metabolic switch alters hepatic lipogenesis, glycogen storage, and detoxification

Besides helping to maintain a reducing intracellular environment, the thioredoxin (Trx) system impacts bioenergetics and drug metabolism. We show that hepatocyte-specific disruption of Txnrd1, encoding Trx reductase-1 (TrxR1), causes a metabolic switch in which lipogenic genes are repressed and periportal hepatocytes become engorged with glycogen. These livers also overexpress machinery for biosynthesis of glutathione and conversion of glycogen into UDP-glucuronate; they stockpile glutathione-S-transferases and UDP-glucuronyl-transferases; and they overexpress xenobiotic exporters. This realigned metabolic profile suggested that the mutant hepatocytes might be preconditioned to more effectively detoxify certain xenobiotic challenges. Hepatocytes convert the pro-toxin acetaminophen (APAP, paracetamol) into cytotoxic N-acetyl-p-benzoquinone imine (NAPQI). APAP defenses include glucuronidation of APAP or glutathionylation of NAPQI, allowing removal by xenobiotic exporters. We found that NAPQI directly inactivates TrxR1, yet Txnrd1-null livers were resistant to APAP-induced hepatotoxicity. Txnrd1-null livers did not have more effective gene expression responses to APAP challenge; however, their constitutive metabolic state supported more robust GSH biosynthesis, glutathionylation, and glucuronidation systems. Following APAP challenge, this effectively sustained the GSH system and attenuated damage.

Nuclear-encoded chloroplast RNA polymerase sigma factor SIG2 activates chloroplast-encoded phycobilisome genes in a red alga, Cyanidioschyzon merolae

The phycobilisome (PBS) is a photosynthetic light-harvesting complex in red algae, whose structural genes are separately encoded by both the nuclear and chloroplast genomes. While the expression of PBS genes in both genomes is responsive to environmental changes to modulate light-harvesting efficiency, little is known about how gene expression of the two genomes is coordinated. In this study, we focused on the four nuclear-encoded chloroplast sigma factors to understand aspects of this coordination, and found that SIG2 directs the expression of chloroplast PBS genes in the red alga Cyanidioschyzon merolae.

Characterization of two pathogenic mutations in cystathionine beta-synthase: different intracellular locations for wild-type and mutant proteins

Cystathionine β-synthase (CBS) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that catalyzes the condensation of homocysteine with serine to generate cystathionine. Homocystinuria is an autosomal recessive disorder commonly caused by a deficiency of CBS activity. Here, we characterized a novel CBS mutation (c.260C>A (p.T87N)) and a previously reported variant (c.700G>A (p.D234N)) found in Venezuelan homocystinuric patients, one nonresponsive and one responsive to vitamin B6. Both mutant proteins were expressed in vitro in prokaryotic and eukaryotic cells, finding lower soluble expression in HEK-293 cells (19% T87N and 23% D234N) compared to wild-type CBS. Residual activities obtained for the mutant proteins were 3.5% T87N and 43% D234N. Gel exclusion chromatography demonstrated a tendency of the T87N mutant to aggregate while the distribution of the D234N mutant was similar to wild-type enzyme. Using immunofluorescence microscopy, an unexpected difference in intracellular localization was observed between the wild-type and mutant proteins. While the T87N mutant exhibited a punctate appearance, the wild-type protein was homogeneously distributed inside the cell. Interestingly, the D234N protein showed both distributions. This study demonstrates that the pathogenic CBS mutations generate unstable proteins that are unable (T87N) or partially unable (D234N) to assemble into a functional enzyme, implying that these mutations might be responsible for the homocystinuria phenotype.

The identification and characterisation of a new deltamethrin resistance-associated gene, UBL40, in the diamondback moth, Plutella xylostella (L.)

Differential expression of ubiquitin was previously reported between Plutella xylostella strains that are resistant or susceptible to the pesticide deltamethrin (DM). This finding hinted at the potential involvement of ubiquitin in deltamethrin resistance, a theory that demanded further testing. Real-time PCR analyses revealed that one of the ubiquitin genes, UBL40, was overexpressed in the deltamethrin-resistant strain during the fourth instar. To investigate the functional relationship between this gene and deltamethrin resistance, RNA interference (RNAi) and cell transfection were utilised. UBL40 knockdown was observed to significantly reduce the level of resistance in RNAi-treated larvae after 48 h. Conversely, overexpression of UBL40 in Drosophila Kc cells conferred a degree of protection against deltamethrin. These results represent the first evidence that UBL40 plays a role in the regulation of deltamethrin resistance in P. xylostella.

Expression of budding yeast FKBP12 confers rapamycin susceptibility to the unicellular red alga Cyanidioschyzon merolae

The target of rapamycin (TOR) is serine/threonine protein kinase that is highly conserved among eukaryotes and can be inactivated by the antibiotic rapamycin through the formation of a ternary complex composed of rapamycin and two proteins, TOR and FKBP12. Differing from fungi and animals, plant FKBP12 proteins are unable to form the ternary complex, and thus plant TORs are insensitive to rapamycin. This has led to a poor understanding of TOR functions in plants. As a first step toward the understanding of TOR function in a rapamycin-insensitive unicellular red alga, Cyanidioschyzon merolae, we constructed a rapamycin-susceptible strain in which the Saccharomyces cerevisiae FKBP12 protein (ScFKBP12) was expressed. Treatment with rapamycin resulted in growth inhibition and decreased polysome formation in this strain. Binding of ScFKBP12 with C. merolae TOR in the presence of rapamycin was demonstrated in vivo and in vitro by pull-down experiments. Moreover, in vitro kinase assay showed that inhibition of C. merolae TOR kinase activity was dependent on ScFKBP12 and rapamycin.

Association of the + 45T>G adiponectin gene polymorphism with insulin resistance in non-diabetic Saudi women

BACKGROUND

The human adiponectin gene variations are associated with obesity, insulin resistance, and diabetes. However, these associations have not been fully examined in a non-diabetic population in Saudi Arabia. We aimed to investigate the association of 45T>G single nucleotide polymorphism (SNP) in the adiponectin gene with total adiponectin levels, insulin resistance (IR), fasting blood glucose (FBG) and other markers of obesity in non-diabetic Saudi females.

METHODS

One hundred non diabetic Saudi females were enrolled in this study. They were further divided according to their body mass index (BMI) into two groups. Group I, 46 non diabetic subjects with normal body weight and group II, 54 overweight and obese females. Adiponectin 45T/G polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Serum adiponectin was measured by ELISA.

RESULTS

Obese women exhibited a higher distribution of TG/GG genotype compared with non-obese women. SNP +45T>G genotypes were associated with higher FBG, insulin levels and HOMA-IR with lower total adiponectin levels in obese Saudi women. Otherwise the all estimated variables revealed non-significant differences among the non-obese genotypes. The observed differences in insulin resistance markers were very significant among women with a higher body weight but not among normal body weight women, thus suggesting that SNP +45T>G effects on insulin sensitivity may depend upon body weight and body fat status.

CONCLUSION

SNP +45T>G of adiponectin gene has a significant role in the development of insulin resistance in Saudi women possibly through an interaction with increase body weight and hypoadiponectinemia.

Kinesin-5: cross-bridging mechanism to targeted clinical therapy

Kinesin motor proteins comprise an ATPase superfamily that works hand in hand with microtubules in every eukaryote. The mitotic kinesins, by virtue of their potential therapeutic role in cancerous cells, have been a major focus of research for the past 28 years since the discovery of the canonical Kinesin-1 heavy chain. Perhaps the simplest player in mitotic spindle assembly, Kinesin-5 (also known as Kif11, Eg5, or kinesin spindle protein, KSP) is a plus-end-directed motor localized to interpolar spindle microtubules and to the spindle poles. Comprised of a homotetramer complex, its function primarily is to slide anti-parallel microtubules apart from one another. Based on multi-faceted analyses of this motor from numerous laboratories over the years, we have learned a great deal about the function of this motor at the atomic level for catalysis and as an integrated element of the cytoskeleton. These data have, in turn, informed the function of motile kinesins on the whole, as well as spearheaded integrative models of the mitotic apparatus in particular and regulation of the microtubule cytoskeleton in general. We review what is known about how this nanomotor works, its place inside the cytoskeleton of cells, and its small-molecule inhibitors that provide a toolbox for understanding motor function and for anticancer treatment in the clinic.

Molecular characterization and expression analysis of PPP1R3C in hypoxia-tolerant Indian catfish, Clarias batrachus (Linnaeus, 1758) under hypoxia

Hypoxia is an important environmental stressor that leads to rapid adaptive changes in metabolic organization. However, the molecular mechanisms of hypoxia tolerance in fish remain largely unknown. The present work was focused on understanding the molecular mechanisms and signaling pathways that may lead to tolerance of Clarias batrachus to hypoxic stress. Protein phosphatase 1 regulatory subunit 3C (PPP1R3C) is a new hypoxia-inducible factor (HIF) targeted gene and is regulated by HIF-1 under hypoxic conditions. Overexpression of PPP1R3C increases glycogen accumulation through activation of several enzymes and processes. In this study, for the first time, full length cDNA of PPP1R3C from C. batrachus was characterized and its expression pattern in the brain, liver, muscle and spleen under short (progressive hypoxia; PH, 1h, 6h and 12h) and long-term (natural) hypoxic conditions was investigated. The complete cDNA of PPP1R3C was of 1499 bp, encoding 285 amino acid residues. The identified protein had a protein phosphatase 1 binding motif and a carbohydrate binding domain, thought to be involved in the regulation of glycogen metabolism. Short-term hypoxia exposure caused significant increase in PPP1R3C transcripts in the liver (6h; 6.96 fold and 12h; 3.91 fold) and muscle (progressive hypoxia; 3.46 fold), while, after long-term hypoxia exposure, significant up-regulation in the liver (7.77 fold) and spleen (6.59 fold) tissues was observed. No significant differences were observed in the brain for any time periods. Thus PPP1R3C may play an important role in the tolerance of C. batrachus to hypoxia.

Are endosomal trafficking parameters better targets for improving mAb pharmacokinetics than FcRn binding affinity?

F.W.R. Brambell deduced the existence of a protective receptor for IgG, the neonatal Fc receptor (FcRn), long before its discovery in the early to mid-1990s. With the coincident, explosive development of IgG-based drugs, FcRn became a popular target for tuning the pharmacokinetics of monoclonal antibodies (mAbs). One aspect of Brambell's initial observation, however, that is seldom discussed since the discovery of the receptor, is the compliance in the mechanism that Brambell observed (saturating at 10s-100s of μM concentration), vs. the comparative stiffness of the receptor kinetics (saturating in the nM range for most species). Although some studies reported that increasing the already very high Fc-FcRn affinity at pH 6.0 further improved mAb half-life, in fact the results were mixed, with later studies increasingly implicating non-FcRn-dependent mechanisms as determinants of mAb pharmacokinetics. Mathematical modelling of the FcRn system has also indicated that the processes determining the pharmacokinetics of mAbs have more nuances than had at first been hypothesised. We propose, in keeping with the latest modelling and experimental evidence reviewed here, that the dynamics of endosomal sorting and trafficking have important roles in the compliant salvage mechanism that Brambell first observed nearly 50 years ago, and therefore also in the pharmacokinetics of mAbs. These ideas lead to many open questions regarding the endosomal trafficking of both FcRn and mAbs and also to what properties of a mAb can be altered to achieve an improvement in pharmacokinetics.

Emulsion PCR-coupled target enrichment: an effective fishing method for high-throughput sequencing of poorly preserved ancient DNA

Due to the difficulties in deep sequencing, high-throughput sequencing of ancient DNA has been limited to exceptionally well-preserved ancient materials. The primary factor is microbial attack popularly observed in the buried materials, and it causes drastic increase in relative ratio of microbial DNA in the extracted DNA. We present a unified strategy in which emulsion PCR is coupled with target enrichment followed by next-generation sequencing. The method made it possible to obtain efficiently non-duplicated reads mapped to target sequences of interest, and this can achieve deep and reliable sequencing of ancient DNA from typical materials, even though poorly preserved.

Ovarian cancer ascites-derived vitronectin and fibronectin: combined purification, molecular features and effects on cell response

BACKGROUND

Intra-abdominal ascites is a complication of ovarian cancers and constitutes a permissive microenvironment for metastasis. Since fibronectin and vitronectin are key actors in ovarian cancer progression, we investigated their occurrence and molecular characteristics in various ascites fluids and the influence of these ascites-derived proteins on cell behavior.

METHODS

Fibronectin and vitronectin were investigated by immunoblotting within various ascites fluids. A combined affinity-based protocol was developed to purify both proteins from the same sample. Each purified protein was characterized with regard to its molecular features (molecular mass of isoforms, tryptophan intramolecular environment, hydrodynamic radii), and its influence on cell adhesion.

RESULTS

Fibronectin and vitronectin were found in all tested ascites. Several milligrams of purified proteins were obtained from ascites of varying initial volumes. Molecular mass isoforms and conformational lability of proteins differed according to the ascites of origin. When incorporated into the cancer cell environment, ascites-derived fibronectin and vitronectin supported cell adhesion and migration with various degrees of efficiency, and induced the recruitment of integrins into focal contacts.

CONCLUSIONS

To our knowledge, this is the first combined purification of two extracellular matrix proteins from a single pathological sample containing a great variety of bioactive molecules. This study highlights that ascites-derived fibronectin and vitronectin exhibit different properties depending on the ascites.

GENERAL SIGNIFICANCE

Investigating the relationships between the molecular properties of ascites components and ovarian cancer cell phenotype according to the ascites may be critical for a better understanding of the recurrence of this lethal disease and for further biomarker identification.

Novel polymorphisms in UTR and coding region of inducible heat shock protein 70.1 gene in tropically adapted Indian zebu cattle (Bos indicus) and riverine buffalo (Bubalus bubalis)

Due to evolutionary divergence, cattle (taurine, and indicine) and buffalo are speculated to have different responses to heat stress condition. Variation in candidate genes associated with a heat-shock response may provide an insight into the dissimilarity and suggest targets for intervention. The present work was undertaken to characterize one of the inducible heat shock protein genes promoter and coding regions in diverse breeds of Indian zebu cattle and buffaloes. The genomic DNA from a panel of 117 unrelated animals representing 14 diversified native cattle breeds and 6 buffalo breeds were utilized to determine the complete sequence and gene diversity of HSP70.1 gene. The coding region of HSP70.1 gene in Indian zebu cattle, Bos taurus and buffalo was similar in length (1,926 bp) encoding a HSP70 protein of 641 amino acids with a calculated molecular weight (Mw) of 70.26 kDa. However buffalo had a longer 5' and 3' untranslated region (UTR) of 204 and 293 nucleotides respectively, in comparison to Indian zebu cattle and Bos taurus wherein length of 5' and 3'-UTR was 172 and 286 nucleotides, respectively. The increased length of buffalo HSP70.1 gene compared to indicine and taurine gene was due to two insertions each in 5' and 3'-UTR. Comparative sequence analysis of cattle (taurine and indicine) and buffalo HSP70.1 gene revealed a total of 54 gene variations (50 SNPs and 4 INDELs) among the three species in the HSP70.1 gene. The minor allele frequencies of these nucleotide variations varied from 0.03 to 0.5 with an average of 0.26. Among the 14 B. indicus cattle breeds studied, a total of 19 polymorphic sites were identified: 4 in the 5'-UTR and 15 in the coding region (of these 2 were non-synonymous). Analysis among buffalo breeds revealed 15 SNPs throughout the gene: 6 at the 5' flanking region and 9 in the coding region. In bubaline 5'-UTR, 2 additional putative transcription factor binding sites (Elk-1 and C-Re1) were identified, other than three common sites (CP2, HSE and Pax-4) observed across all the analyzed animals. No polymorphism was found within the 3'-UTR of Indian cattle or buffalo as it was found to be monomorphic. The promoter sequences generated in 117 individuals showed a rich array of sequence elements known to be involved in transcription regulation. A total of 11 nucleotide changes were observed in the promoter sequence across the analyzed species, 3 of these changes were located within the potential transcription factor binding domains. We also identified 4 microsatellite markers within the buffalo HSP70.1 gene and 3 microsatellites within bovine HSP70.1. The present study identified several distinct changes across indicine, taurine and bubaline HSP70.1 genes that could further be evaluated as molecular markers for thermotolerance.

Molecular cloning and characterization of TNFSF14 (LIGHT) and its receptor TNFRSF14 (HVEM) in guinea pig (Cavia porcellus)

LIGHT (lymphotoxin-related inducible ligand that competes with herpes simplex virus (HSV) glycoprotein D for herpesvirus entry mediator on T cells) is a member of the tumor necrosis factor (TNF) ligand superfamily, which plays important roles in inflammatory and immune responses. In the present study, the cDNAs of guinea pig (Cavia porcellus) LIGHT (designated as gpLIGHT) and its receptor herpes virus entry mediator (designated as gpHVEM) were amplified from spleen by reverse transcription polymerase chain reaction (RT-PCR). The ORFs of gpLIGHT and gpHVEM cover 726 and 861 bp, encoding predicted proteins with 241 and 286 aas, respectively. The three-dimensional (3D) structure, phylogenetic relationships, and characterization of both genes were also analyzed. We also generated a 3D model to verify interaction between the two proteins. Real-time quantitative PCR (qPCR) analysis revealed that both LIGHT and HVEM are constitutively expressed in guinea pig various tissues. A fusion protein SUMO (Small Ubiquitin-like Modifier)-gpsLIGHT (the soluble mature part of gpLIGHT) was efficiently expressed in Escherichia coli BL21 (DE3) and purified using metal chelate affinity chromatography (Ni-NTA). Laser scanning confocal microscopy (LSCM) showed that gpsLIGHT can bind its receptors on T cells. The LIGHT-HVEM signaling pathway plays an important role in the immune system, and our results might provide a platform for further research into the effects of LIGHT and HVEM.