Human LC3B Reporter THP-1 Cells

Monitoring autophagy activity 

THP1-Difluo™ hLC3 reporter cells are designed to monitor the autophagic flux by means of a fluorescent-labeled LC3B protein.

These cells, derived from the THP-1 human monocytic cell line, express the RFP::GFP::LC3 fusion protein in which the human LC3B (microtubule-associated protein 1 light chain 3 beta) is fused to two fluorescent reporter proteins: RFP (acid-stable) and GFP (acid-sensitive). The LC3B protein is a good marker to assess the autophagic flux since it is recruited from the cytosol to be associated to all the autophagic structures: the nascent autophagosome (called the isolation membrane), the complete autophagosome and the autolysosome. Upon autophagy induction, diffuse cytoplasmic fluorescence shifts to autophagosomes and autolysosomes as fluorescent puncta.

Monitoring of autophagy activity relies on microscopy visualization of fluorescent puncta, progressive degradation of the GFP, and concurrent increase of RFP signal in autolysosomes. The number of fluorescent punctate structures per cell, the percentages of RFP-GFP positive and RFP positive cells can be used to assess autophagic flux as described previously [1,2].

Read our review on Autophagy and innate immunity.

References

1. Loos B. et al. 2014. Defining and measuring autophagosome flux- concept and reality. Autophagy. 2014;10(11):2087-96. 
2. Kimura S. et al., 2007. Dissection of the autophagosome maturation process by a novel reporter protein, tandem fluorescent- tagged LC3. Autophagy. 3(5):452-60.