An alternative approach to synthesize cDNA bypassing traditional reverse transcription

An alternative strategy to generate coding sequence of macrophage migration inhibitory factor-2 of Wuchereria bancrofti

Background & objectives:

Different developmental stages of Wuchereria bancrofti, the major causal organism of lymphatic filariasis (LF), are difficult to obtain. Beside this limitation, to obtain complete coding sequence (CDS) of a gene one has to isolate mRNA and perform subsequent cDNA synthesis which is laborious and not successful at times. In this study, an alternative strategy employing polymerase chain reaction (PCR) was optimized and validated, to generate CDS of Macrophage migration Inhibitory Factor-2 (wbMIF-2), a gene expressed in the transition stage between L3 to L4.

Methods:

The genomic DNA of W. bancrofti microfilariae was extracted and used to amplify the full length wbMIF-2 gene (4.275 kb). This amplified product was used as a template for amplifying the exons separately, using the overlapping primers, which were then assembled through another round of PCR.

Results:

A simple strategy was developed based on PCR, which is used routinely in molecular biology laboratories. The amplified CDS of 363 bp of wbMIF-2 generated using genomic DNA splicing technique was devoid of any intronic sequence.

Interpretation & conclusions:

The cDNA of wbMIF-2 gene was successfully amplified from genomic DNA of microfilarial stage of W. bancrofti thus circumventing the use of inaccessible L3-L4 transitional stage of this parasite. This strategy is useful for generating CDS of genes from parasites that have restricted availability.

Comparative insight into expression of recombinant human VEGF111b, a newly identified anti-angiogenic isoform, in eukaryotic cell lines

VEGF-A is a critical growth factor in tumor growth and progression. Two families of VEGF-A isoforms are produced through alternative splicing including VEGFxxx pro-angiogenic and VEGFxxxb anti-angiogenic isoforms. VEGF111b is a new member of the VEGFxxxb family that is induced by mitomycin C and doesn't express in normal conditions. The potent anti-angiogenic properties of VEGF-111b and its remarkable resistance to proteolysis make it an interesting alternative candidate for therapeutic use in all types of cancers. Here, the recombinant VEGF-111b cDNA with insertion of intronic sequence was constructed by using a class IIs restriction enzyme-based method. The recombinant pBud-VEGF111b was transfected into CHO dhfr(-) and HEK 293 cell lines which are currently the standard hosts for the production of candidate therapeutic proteins. Then, the VEGF-111b expression was evaluated in two cell lines using the Real-time PCR. The production of VEGF-111b protein was also investigated here by dot blotting. The VEGF expression was increased about 109 and 185-folds in transfected CHO-dhfr(-) and HEK 293 cells, respectively, in comparison with the un-transfected cells. Dot blotting approach confirmed that both cell lines have successfully produced the VEGF-111b protein.