One-Step Construction of Lentiviral Reporter Using Red-Mediated Recombination

Hsa-miR-301a-3p inhibited the killing effect of natural killer cells on non-small cell lung cancer cells by regulating RUNX3

BACKGROUND

Non-small cell lung cancer (NSCLC) is the most commonly diagnosed solid tumor. Natural killer (NK) cell-based immunotherapy is a promising anti-tumor strategy in various cancers including NSCLC.

OBJECTIVE

We aimed to investigate the specific mechanisms that regulate the killing effect of NK cells to NSCLC cells.

METHODS

Reverse transcription-quantitative PCR (RT-qPCR) assay was applied to measure the levels of hsa-microRNA (miR)-301a-3p and Runt-related transcription factor 3 (RUNX3). Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of IFN-γ and TNF-α. Lactate dehydrogenase assay was applied to detect the killing effect of NK cells. Dualluciferase reporter assay and RNA immunoprecipitation (RIP) assay were carried out to confirm the regulatory relationship between hsa-miR-301a-3p and RUNX3.

RESULTS

A low expression of hsa-miR-301a-3p was observed in NK cells stimulated by IL-2. The levels of IFN-γ and TNF-α were increased in NK cells of the IL-2 group. Overexpression of hsa-miR-301a-3p reduced the levels of IFN-γ and TNF-α as well as the killing effect of NK cells. Furthermore, RUNX3 was identified to be a target of hsamiR-301a-3p. hsa-miR-301a-3p suppressed the cytotoxicity of NK cells to NSCLC cells by inhibiting the expression of RUNX3. We found hsa-miR-301a-3p promoted tumor growth by suppressing the killing effect of NK cells against NSCLC cells in vivo.

CONCLUSIONS

Hsa-miR-301a-3p suppressed the killing effect of NK cells on NSCLC cells by targeting RUNX3, which may provide promising strategies for NK cell-based antitumor therapies.

Characterization of isoform expression and subcellular distribution of MYPT1 in intestinal epithelial cells

The regulation of intestinal epithelial permeability requires phosphorylation of myosin regulatory light chain (MLC). The phosphorylation status of MLC is regulated by myosin light chain phosphatase (MLCP) activities. The activity of the catalytic subunit of MLCP (PP1cδ) toward MLC depends on its regulatory subunit (MYPT1). In this study, we revealed the presence of two MYPT1 isoforms, full length and variant 2 in human intestinal (Caco-2) epithelial cells and isolated intestinal epithelial cells (IECs) from mice. In confluent Caco-2 cells, MYPT1 was distributed at cell-cell contacts and colocalized with F-actin. These results suggest that MYPT1 isoforms are expressed in intestinal epithelial cells and MYPT1 may be involved in the regulation of intestinal epithelial barrier function.

An easy and versatile 2-step protocol for targeted modification and subcloning of DNA from bacterial artificial chromosomes using non-commercial plasmids

Background

Promoter-specific expression of foreign DNA in transgenic organisms often relies on bacterial artificial chromosomes (BACs). This approach requires modification and subcloning of BAC-DNA by recombineering technologies in Escherichia coli. Most current protocols rely on commercial kits or isolation of BACs, their transfer between different host strains, and their restriction.

Findings

In this report we present a 2-step protocol for efficient modification and subcloning of DNA from bacterial artificial chromosomes using the non-commercial plasmids pKM208 and pTP223, distributed from addgene.com. A targeting cassette was successfully integrated into a BAC and 42 kb of this construct were subcloned. Both a plasmid-derived substrate with longer homology arms and a PCR-generated substrate with short homology arms (50 bp) were used for recombination. pKM208 and pTP223 contain all required genes for recombineering, but differ in their antibiotic resistance genes. This makes the system independent of the selection markers on the DNA molecules targeted for recombination.

Conclusions

The time and cost saving protocol presented here compares favorably to currently used systems. Using non-commercial plasmids, it allows targeted modification and cloning of large DNA (> 40 kb) fragments in vivo without restriction and ligation. Furthermore, both steps are performed in the same host eliminating the need to isolate BAC DNA and to use different bacterial strains.