GlycoBIST: A System for Automatic Glycan Profiling of a Target Protein Using Milli-Bead Array in a Tip.

Lectin is a biomolecule that recognizes a specific part of glycans and, thus, has been used widely as a probe for glycoprotein analysis. Owing to the wide repertoire in nature combined with the recent two decades of advances in microarray technology, the multiplexed use of lectins has been widely used for glycan profiling of endogenous proteins. Because protein glycosylation is recognized as being biologically important and is expected to be a reliable disease marker, lectin microarray analysis with highly sensitive detection has been used to discover disease-relevant glycosylation alterations. However, the conventional system is limited to research purposes; thus, its implementation in clinical settings is warranted. Here, we provide an automatic glycan profiling method using GlycoBIST. A unique array format is used for 10-plexed lectin-glycoprotein interaction analysis on 1-mm-sized beads, which are arranged vertically in a capillary-shaped plastic tip. Using a one-boxed autopipetting machine, the whole process (including interaction, washing, and detection) is performed automatically and serially, resulting in reproducible measurements. In this article, a typical method for glycan profiling of a purified glycoprotein and the fabrication of GlycoBIST tips is explained. © 2020 by John Wiley & Sons, Inc. Basic Protocol 1: Fabrication of a GlycoBIST tip Basic Protocol 2: Automatic profiling of a target glycoprotein using GlycoBIST.

Male-specific cardiac pathologies in mice lacking either the A or B subunit of factor XIII.

Factor XIII (FXIII) is a proenzyme of plasma transglutaminase consisting of enzymatic A subunits (FXIII-A) and non-catalytic B subunits (FXIII-B), and acts in haemostasis and wound healing. We generated mice lacking either FXIII-A or FXIII-B to investigate the physiological functions of FXIII in vivo. A longitudinal study was carried out using the gene-targeted mice to explore the possible effects of FXIII deficiency on aging. Survival rates of FXIII-A(-/-) males decreased to approximately 50% at 10 months after birth, although most FXIII-A(-/-) females and both genders of wild-type mice survived. Four FXIII-A(-/-) males died of severe intra-thoracic haemorrhage, and a large haematoma was found in their hearts. Haemorrhage, haemosiderin deposition and/or fibrosis were observed in the hearts of other dead FXIII-A(-/-) males. Fibrosis together with haemosiderin deposition was also found in the hearts of FXIII-A(-/-) males sacrificed. The in-vivo cardiac function was normal in FXIII-A(-/-) mice when compared with wild-type mice despite the presence of significant cardiac fibrosis. Although survival rates for both genders of the FXIII-B(-/-) and wild-type mice did not differ, mild fibrosis together with haemosiderin deposits were only found in the hearts of the sacrificed FXIII-B(-/-) males. Carditis and fibrosis in FXIII-deficient mice might be caused by a faulty or delayed reparative process that was initiated by abnormal haemorrhagic events within heart tissue. It is important therefore to examine possible cardiac involvement in human patients with congenital FXIII deficiency.

Administration of factor XIII B subunit increased plasma factor XIII A subunit levels in factor XIII B subunit knock-out mice.

Factor XIII (FXIII) is a proenzyme of plasma transglutaminase consisting of enzymatic A (FXIII-A) and noncatalytic B subunits (FXIII-B), and acts in hemostasis and wound healing. We freshly generated mice lacking either FXIII-A or FXIII-B to investigate the physiological functions of FXIII in vivo. Mice carrying the disrupted allele were born at the expected Mendelian ratios, and the homozygous mice were viable and fertile under specific pathogen-free conditions. Although all homozygous and heterozygous mice showed no marked difference from the wild-type animals in general appearance, homozygous mice of either FXIII-A- or FXIII-B-deficiency did have prolonged bleeding times. It was confirmed that thrombin-dependent amine incorporation and fibrin-crosslinking in plasma were undetectable in the FXIII-A-deficient mice and markedly reduced in the FXIII-B-deficient mice; however, the gene expression of each subunit was regulated independently. Recombinant human FXIII-B (rFXIII-B) was expressed in a baculovirus expression system. When rFXIII-B was injected into FXIII-B-deficient mice, FXIII-A levels, fibrin crosslinking, and amine-incorporation activities increased in their plasma, indicating that FXIII-B assisted the maintenance of FXIII-A levels in the circulation. These mouse strains will be useful in exploring the possible pathophysiological roles of each subunit in vivo.

Development of a lectin microarray based on an evanescent-field fluorescence principle.

To investigate protein-carbohydrate interactions in a comprehensive and high-throughput manner, carbohydrate biosensors including microarrays have recently attracted increased attention. In this context, carbohydrate and lectin microarrays are emerging as techniques to meet such requisites. However, most of these methods adopt a conventional immuno-detection system, which requires repetitive washing steps before detection. Since lectin-carbohydrate interactions are relatively weak compared with those between antigens and antibodies, a more precise analytical method, which does not require any washing step, is desirable. We describe here a novel platform for lectin microarray that enables direct observation of lectin-carbohydrate interactions under equilibrium conditions, on the basis of an evanescent-field fluorescence-assisted detection principle. This method allows the analysis of a panel of glycoproteins (glycopeptides) in an extremely sensitive manner. The system also allows real-time observation of lectin-glycoprotein interactions in an aqueous phase. No washing procedures are required, thus relatively weak interactions are detectable. The described lectin microarray is expected to be useful for various fields of glycomics requiring high-throughput analysis of not only purified glycoproteins but also of crude samples.

Application of lectin microarray to crude samples: differential glycan profiling of lec mutants.

We recently developed a novel system for lectin microarray based on the evanescent-field fluorescence-detection principle, by which even weak lectin-oligosaccharide interactions are detectable without a washing procedure. For its practical application, cell glycan analysis was performed for Chinese hamster ovary (CHO) cells and their glycan profile was compared with those of their glycosylation-defective Lec mutants. Each of the cell surface extracts gave a significantly different profile from that of the parental CHO cells in a manner reflecting denoted biosynthetic features. Hence, the developed lectin microarray system is considered to be fully applicable for differential glycan profiling of crude samples.

Evanescent-field fluorescence-assisted lectin microarray: a new strategy for glycan profiling.

Glycans have important roles in living organisms with their structural diversity. Thus, glycomics, especially aspects involving the assignment of functional glycans in a high-throughput manner, has been an emerging field in the postproteomics era. To date, however, there has been no versatile method for glycan profiling. Here we describe a new microarray procedure based on an evanescent-field fluorescence-detection principle, which allows sensitive, real-time observation of multiple lectin-carbohydrate interactions under equilibrium conditions. The method allows quantitative detection of even weak lectin-carbohydrate interactions (dissociation constant, K(d) > 10(-6) M) as fluorescent signals for 39 immobilized lectins. We derived fully specific signal patterns for various Cy3-labeled glycoproteins, glycopeptides and tetramethylrhodamine (TMR)-labeled oligosaccharides. The obtained results were consistent with the previous reports of glycoprotein and lectin specificities. We investigated the latter aspects in detail by frontal affinity chromatography, another profiling method. Thus, the developed lectin microarray should contribute to creation of a new paradigm for glycomics.

R255h amino acid substitution of protein Z identified in patients with factor V Leiden mutation.

The clinical significance of diminished protein Z in plasma is controversial. Studies in mice demonstrated that deficiency of protein Z dramatically increases the prothrombotic tendency of factor V Leiden mutation. This finding was confirmed by initial results in humans, indicating that thromboembolism in factor V Leiden patients with lowered protein Z level occurs earlier than in patients with normal protein Z levels. Consequently, the aim of our present study was to find out whether genetic alterations of protein Z were demonstrated in patients with factor V Leiden mutation and early onset of thromboembolic disease. DNA-sequencing of the protein Z gene was performed in two patients with factor V Leiden mutation, early onset of thromboembolism, and lowered protein Z levels. In both patients, R255H substitution of the protein Z gene was identified. Subsequently, the R255H substitution was also found in 12 of 132 additional patients. Patients presenting with the R255H substitution in addition to factor V Leiden mutation showed thromboembolic events more frequently than factor V Leiden patients without R255H substitution of the protein Z gene. In conclusion, R255H substitution of the protein Z gene seems to influence clinical symptoms of thromboembolism in factor V Leiden patients.

A naturally occurring E30Q mutation in the Gla domain of protein Z causes its impaired secretion and subsequent deficiency.

Protein Z is a vitamin K-dependent glycoprotein that plays a role in the regulation of coagulation. A nucleotide substitution of G by C in exon II of the protein Z gene, resulting in the replacement of Glu-30 with Gln (E30Q), and a G to A transition at the 79th nucleotide in intron F (IntF79G/A) were heterozygously identified in a patient with a severe thrombotic tendency, whose plasma protein Z level was about 15% of normal. Other vitamin K-dependent coagulation factors were within normal ranges. Glu-30 is one of 13 gamma-carboxylation sites in protein Z and is well conserved among vitamin K-dependent proteins. Expression studies revealed that the E30Q mutant was not released from synthesizing cells, although wild-type protein Z was readily secreted in a vitamin K-dependent fashion. The E30Q mutant was N-glycosylated, gamma-carboxylated, and translocated from the endoplasmic reticulum (ER) to the Golgi in the presence of vitamin K, as was the wild type. Coexpression of E30Q with wild-type protein Z interfered with the secretion of the wild type, while only a minor or no effect was observed on the secretion of factor X and plasminogen. The IntF79A allele has been reported to be also associated with lowered protein Z levels.

Factor XIII A subunit-deficient mice developed severe uterine bleeding events and subsequent spontaneous miscarriages.

To understand the molecular pathology of factor XIII (FXIII) deficiency in vivo, its A subunit (FXIIIA)-knockout (KO) mice were functionally analyzed. Although homozygous FXIIIA female KO mice were capable of becoming pregnant, most of them died due to excessive vaginal bleeding during gestation. Abdominal incisions revealed that the uteri of the dead mice were filled with blood and that some embryos were much smaller than others within a single uterus. A series of histologic examinations of the pregnant animals suggested that massive placental hemorrhage and subsequent necrosis developed in the uteri of the FXIIIA KO mice on day 10 of gestation. This was true regardless of the genotypes of fetuses. These results are reminiscent of spontaneous miscarriage in pregnant humans with FXIII deficiency and indicate that maternal FXIII plays a critical role in uterine hemostasis and maintenance of the placenta during gestation.