Third-Generation Covalent TMP-Tag for Fast Labeling and Multiplexed Imaging of Cellular Proteins.

Self-labeling protein tags can introduce advanced molecular motifs to specific cellular proteins. Here we introduce the third-generation covalent TMP-tag (TMP-tag3) and showcase its comparison with HaloTag and SNAP-tag. TMP-tag3 is based on a proximity-induced covalent Michael addition between an engineered Cys of E. coli dihydrofolate reductase (eDHFR) and optimized trimethoprim (TMP)-acrylamide conjugates with minimal linkers. Compared to previous versions, the TMP-tag3 features an enhanced permeability when conjugated to fluorogenic spirocyclic rhodamines. As a small protein, the 18-kD eDHFR is advantageous in tagging selected mitochondrial proteins which are less compatible with bulkier HaloTag fusions. The proximal N-C termini of eDHFR also enable facile insertion into various protein loops. TMP-tag3, HaloTag, and SNAP-tag are orthogonal to each other, collectively forming a toolbox for multiplexed live-cell imaging of cellular proteins under fluorescence nanoscopy.

[Effects of Sialidase Inhibitor on Proliferation and Apoptosis of Endometrial Cancer Cells].

OBJECTIVES: To explore the effects of sialidase inhibitor on the proliferation and apoptosis of endometrial cancer Ishikawa cells. METHODS: Ishikawa cells were cultured and divided into 2 groups: control group and sialidase inhibitor N-Acetyl-2, 3-dehydro-2-deoxyneuraminic acid (DANA) treated group. After the sialidase activity was compared between the two groups, the expression level of matrix metalloproteinases (MMPs), proliferating cell nuclear antigen (PCNA), apoptosis rate and proliferation ability were detected by immunofluorescence staining, flow cytometry or MTT assay. RESULTS: With the treatment of DANA, the activity of sialidase in the cell culture supernatant was suppressed while MMPs expression levels and apoptosis rate of Ishikawa cells were decreased. The expression level of PCNA and cell proliferation showed no statistical differences in two groups. CONCLUSIONS: Sialidase could affect the invasive ability and apoptosis rate of Ishikawa cells, but it seems no effect on cell proliferation.