Prokaryotic expression and purification of soluble maize Ac transposase

Preparation of an anti-NEK2 monoclonal antibody and its application in liver cancer

Background

Never in mitosis gene-A (NIMA)-related expressed kinase 2 (NEK2) is a serine/threonine protein kinase regulated by the cell cycle. The purpose of this study was to obtain NEK2 protein to prepare an anti-NEK2 monoclonal antibody (mAb) and explore the application of the anti-NEK2 mAb of therapeutic and diagnostic in hepatocellular carcinoma (HCC).

Results

The NEK2 gene sequence was cloned from the normal liver cell line HL7702, and the full-length NEK2 gene sequence was cloned into the prokaryotic expression vector pET30a and transformed into Escherichia coli BL21 (DE3) cells. The recombinant fusion protein was obtained under optimized conditions and injected in BALB/c mice to prepare an anti-NEK2 mAb. By screening, we obtained a stable hybridoma cell line named 3A3 that could stably secrete anti-NEK2 mAb. Anti-NEK2 3A3 mAb was purified from ascites fluid. The isotype was IgG1, and the affinity constant (K_aff) was 6.0 × 10⁸ L/mol. Western blot, indirect enzyme-linked immunosorbent assay (iELISA), immunofluorescence and immunocytochemical analyses showed that the mAb could specifically recognize the NEK2 protein. MTT assays showed that the mAb 3A3 could inhibit the proliferation of HCC cells. KEGG pathway analysis showed that NEK2 might affected pathways of the cell cycle. Moreover, NEK2-related genes were mainly enriched in the S and G2 phases and might act as tumor-promoting genes by regulating the S/G2 phase transition of HCC cells.

Conclusions

An anti-NEK2 mAb with high potency, high affinity and high specificity was prepared by prokaryotic expression system in this study and may be used in the establishment of ELISA detection kits and targeted treatment of liver cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12896-021-00717-3.

Preparation of a novel monoclonal antibody against caprine interleukin-17A and its applications in immunofluorescence and immunohistochemistry assays

BACKGROUND

Interleukin-17 (IL-17), the characteristic cytokine secreted by T helper 17 lymphocytes (Th17 cells), plays a pivotal role in host defense and many inflammatory or autoimmune diseases. The aim of this study was to obtain purified protein caprine IL-17A (cIL-17A) as an antigen for preparing an IL-17A-specific monoclonal antibody (mAb).

RESULTS

The coding sequence (CDS) region of cIL-17A was cloned from the peripheral blood mononuclear cells (PBMCs) of dairy goats and then inserted into the expression vector PET 32a and transformed into competent TransB (DE3) cells. Recombinant fusion protein obtained under optimized conditions was used to immunize BALB/c mice for preparing monoclonal antibodies. Finally, the supernatants of two hybridoma cell lines showing positive reaction with the recombinant fusion protein and negative reaction with fusion tags of PET 32a were collected for western blot, immunofluorescence (IF) and immunohistochemistry (IHC) analysis. Our results showed that the maximum amount of soluble protein could be obtained directly in the supernatant when the recombinant expression cells were induced by isopropyl-β-d-thiogalactoside (IPTG) at a concentration of 0.3 mmol/L at 16 °C for 42 h. Western blot analysis showed that the mAb H8 could recognize the eukaryotically expressed cIL-17A in the supernatant of transfected HEK293T cells. Immunofluorescence and immunohistochemistry assays showed that mAb H8 could strongly recognize both the eukaryotically expressed and natural cIL-17A.

CONCLUSIONS

The monoclonal antibody mAb H8 prepared in this study may be a potential tool for the detection of cIL-17A and beneficial for investigating the pathogenesis of various IL-17-associated diseases.

Redox-dependent interaction between thaumatin-like protein and β-glucan influences malting quality of barley

Barley is the cornerstone of the malting and brewing industry. It is known that 250 quantitative trait loci (QTLs) of the grain are associated with 19 malting-quality phenotypes. However, only a few of the contributing genetic components have been identified. One of these, on chromosome 4H, contains a major malting QTL, QTL2, located near the telomeric region that accounts, respectively, for 28.9% and 37.6% of the variation in the β-glucan and extract fractions of malt. In the current study, we dissected the QTL2 region using an expression- and microsynteny-based approach. From a set of 22 expressed sequence tags expressed in seeds at the malting stage, we identified a candidate gene, TLP8 (thaumatin-like protein 8), which was differentially expressed and influenced malting quality. Transcript abundance and protein profiles of TLP8 were studied in different malt and feed varieties using quantitative PCR, immunoblotting, and enzyme-linked immunosorbent assay (ELISA). The experiments demonstrated that TLP8 binds to insoluble (1, 3, 1, 4)-β-D glucan in grain extracts, thereby facilitating the removal of this undesirable polysaccharide during malting. Further, the binding of TLP8 to β-glucan was dependent on redox. These findings represent a stride forward in our understanding of the malting process and provide a foundation for future improvements in the final beer-making process.

Prokaryotic expression and purification of soluble goldfish Tgf2 transposase with transposition activity

Goldfish Tgf2 transposon of Hobo/Activator/Tam3 (hAT) family can mediate gene insertion in a variety of aquacultural fish species by transposition; however, the protein structure of Tgf2 transposase (TPase) is still poorly understood. To express the goldfish Tgf2 TPase in Escherichia coli, the 2061-bp coding region was cloned into pET-28a(+) expression vector containing an N-terminal (His)6-tag. The pET-28a(+)-Tgf2 TPase expression cassette was transformed into Rosetta 1 (DE3) E. coli lines. A high yield of soluble proteins with molecular weight of ~80 kDa was obtained by optimized cultures including low-temperature (22 °C) incubation and early log phase (OD600 = 0.3-0.4) induction. Mass spectrometry analysis following trypsin digestion of the recombinant proteins confirmed a Tgf2 TPase component in the eluate of Ni(2+)-affinity chromatography. When co-injected into 1-2 cell embryos with a donor plasmid harboring a Tgf2 cis-element, the prokaryotic expressed Tgf2 TPase can mediate high rates (45 %) of transposition in blunt snout bream (Megalobrama amblycephala). Transposition was proved by the presence of 8-bp random direct repeats at the target sites, which is the signature of hAT family transposons. Production of the Tgf2 Tpase protein in a soluble and active form not only allows further investigation of its structure, but provides an alternative tool for fish transgenesis and insertional mutagenesis.

Polymorphic homoeolog of key gene of RdDM pathway, ARGONAUTE4_9 class is associated with pre-harvest sprouting in wheat (Triticum aestivum L.)

Resistance to pre-harvest sprouting (PHS) is an important objective for the genetic improvement of many cereal crops, including wheat. Resistance, or susceptibility, to PHS is mainly influenced by seed dormancy, a complex trait. Reduced seed dormancy is the most important aspect of seed germination on a spike prior to harvesting, but it is influenced by various environmental factors including light, temperature and abiotic stresses. The basic genetic framework of seed dormancy depends on the antagonistic action of abscisic acid (ABA) and gibberellic acid (GA) to promote dormancy and germination. Recent studies have revealed a role for epigenetic changes, predominantly histone modifications, in controlling seed dormancy. To investigate the role of DNA methylation in seed dormancy, we explored the role of ARGONAUTE4_9 class genes in seed development and dormancy in wheat. Our results indicate that the two wheat AGO4_9 class genes i.e. AGO802 and AGO804 map to chromosomes 3S and 1S are preferentially expressed in the embryos of developing seeds. Differential expressions of AGO802-B in the embryos of PHS resistant and susceptible varieties also relates with DNA polymorphism in various wheat varieties due to an insertion of a SINE-like element into this gene. DNA methylation patterns of the embryonic tissue from six PHS resistant and susceptible varieties demonstrate a correlation with this polymorphism. These results suggest a possible role for AGO802-B in seed dormancy and PHS resistance through the modulation of DNA methylation.

A root-specific wall-associated kinase gene, HvWAK1, regulates root growth and is highly divergent in barley and other cereals

Wall-associated receptor-like kinases (WAKs) are important candidates for directly linking the extracellular matrix with intracellular compartments and are involved in developmental processes and stress response. WAK gene family has been identified in plants such as Arabidopsis and rice. Here, we present a detailed analysis of the WAK1 gene from barley cv. Golden Promise, mapped to chromosome 5H. Three BAC clones corresponding to the WAK fragment were sequenced and the full-length WAK1 gene was characterized. The gene has three exons and two short introns with a coding region of 2,178 bp encoding a protein of 725 amino acids. A regulatory region was analyzed in -1,000 bp sequence upstream to start codon. Using conserved domains database and SMART, various conserved domains such as GUB WAK Bind, epidermal growth factor CA, and protein kinase C as well as other regions like signal peptides, active sites, and transmembrane domains were identified. The gene organization of HvWAK1 was compared with wheat (TaWAK1) and Arabidopsis (AtWAK1), suggesting that the WAK1 gene organization has remained highly conserved. Nonetheless, WAK1 was found to be highly divergent when compared with sequences available from barley cv. Haruna Nijo (50 %), rice (46 %), wheat (21 %), Arabidopsis (25 %), and maize (19 %). This divergence may have facilitated a better adaptation to surrounding environments due to its role in communication between the extracellular matrix, cell, and outer environment. Semiquantitative RT-PCR-based expression analysis indicates HvWAK1 expression is specific to roots. Significant differences in root growth between GP wild type and GP-Ds mutant seedlings were observed under control and salt stress conditions.