[Expression and purification of FLT3 and FLT3-ITD mutated proteins in HEK293T cells].

Objective To construct the eukaryotic expression vectors of human fms related tyrosine kinase 3 (FLT3) gene and FLT3-internal tandem duplication (FLT3-ITD) mutants and purify the native proteins through immunoprecipitation from HEK293T cell lysates. Methods The cDNA fragments of FLT3wt and FLT3-ITD were amplified from bone marrow cells of healthy individuals and FLT3-ITD-mutated acute myeloid leukemia (AML) patients with specific primers, and the PCR products were cloned in CD530A-T2A-GFP expression vectors. FLT3wt and FLT3-ITD plasmids were transfected in HEK293T cells by Polyjet reagent, and the recombinant proteins were purified by immunoprecipitation and competing elution methods. Results FLT3wt and FLT3-ITD-mutated DNA sequences were successfully cloned in CD530A-T2A-GFP expression vectors. FLT3wt and FLT3-ITD mutated proteins were successfully expressed and purified in HEK293T cells as verified by Western blotting and sliver staining. Conclusion FLT3wt and FLT3-ITD expression vectors were successfully constructed, and purified proteins were successfully obtained from HEK293T cells.

Enzyme-free and sensitive electrochemical determination of the FLT3 gene based on a dual signal amplified strategy: Controlled nanomaterial multilayers and a target-catalyzed hairpin assembly.

An isothermal, enzyme-free and sensitive electrochemical DNA sensor was developed for the detection of the FLT3 gene in acute myeloid leukemia (AML). First, aminated multi-walled carbon nanotubes (AMWNTs) and gold nanoparticles (AuNPs) were alternately self-assembled on a gold electrode using a layer-by-layer strategy. Then, the hairpin DNA probe 1 (H1), with a thiol group at the 3' end and a ferrocenyl moiety (Fc) at the 5' end, was immobilized on the AMWNTs/AuNPs multilayer films through Au-S bonding. When the target DNA (TD) appeared, it hybridized with and opened the hairpin structure of H1, and Fc was forced away from the electrode surface, leading to a significant decrease in the current peak of square wave voltammetry. Subsequently, the hairpin DNA probe 2 (H2) bound to H1, freeing the TD to trigger another reaction cycle. The combination of this target-catalyzed hairpin assembly and the LBL assembly of nanomaterials achieved a detection limit of 0.1 pM with a wide linear range of 0.1-1000 pM. The sensor discriminated between mismatched DNA and the target DNA with high selectivity. This dual signal amplification strategy is relatively simple and inexpensive because it does not need any enzymes or sophisticated equipment and successfully assayed the FLT3 gene from real samples.

Molecular genetic tests for FLT3, NPM1, and CEBPA in acute myeloid leukemia.

Patients with acute myeloid leukemia (AML) and a normal karyotype constitute the single largest cytogenetic group of AML. It is important to identify prognostic markers that predict patients' outcome more precisely. The presence of mutations in FLT3 (FMS-like tyrosine kinase 3), NPM1 (Nucleophosmin), and CEBPA (CCAAT/enhancer-binding protein alpha) genes hold prognostic significance in patients with AML and normal cytogenetics. Therefore, mutation identification may help to optimize therapeutic approaches in this group of patients. Polymerase chain reaction (PCR)-based fragment length analysis for mutations in FLT3 and NPM1 has been shown to be a fast and sensitive method, while nucleotide sequencing represents a gold standard for CEBPA heterogeneous mutational screening. We describe both fragment length assay and sequencing methods for mutational analysis of these three genes.

Online nanoflow multidimensional fractionation for high efficiency phosphopeptide analysis.

Despite intense, continued interest in global analyses of signaling cascades through mass spectrometry-based studies, the large-scale, systematic production of phosphoproteomics data has been hampered in-part by inefficient fractionation strategies subsequent to phosphopeptide enrichment. Here we explore two novel multidimensional fractionation strategies for analysis of phosphopeptides. In the first technique we utilize aliphatic ion pairing agents to improve retention of phosphopeptides at high pH in the first dimension of a two-dimensional RP-RP. The second approach is based on the addition of strong anion exchange as the second dimension in a three-dimensional reversed phase (RP)-strong anion exchange (SAX)-RP configuration. Both techniques provide for automated, online data acquisition, with the 3-D platform providing the highest performance both in terms of separation peak capacity and the number of unique phosphopeptide sequences identified per µg of cell lysate consumed. Our integrated RP-SAX-RP platform provides several analytical figures of merit, including: (1) orthogonal separation mechanisms in each dimension; (2) high separation peak capacity (3) efficient retention of singly- and multiply-phosphorylated peptides; (4) compatibility with automated, online LC-MS analysis. We demonstrate the reproducibility of RP-SAX-RP and apply it to the analysis of phosphopeptides derived from multiple biological contexts, including an in vitro model of acute myeloid leukemia in addition to primary polyclonal CD8(+) T-cells activated in vivo through bacterial infection and then purified from a single mouse.