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The epithelial mesenchymal transition (EMT) plays significant roles in the progression of cancer and fibrotic disease. Moreover, this process is reversible, resulting in mesenchymal epithelial transition (MET), which plays an important role in cancer metastasis. There is a lack of methods to trace and target EMT cells using synthetic biology circuits, which makes it difficult to study the cell fate or develop targeted treatments. In this study, we introduced responsive EMT sensing circuits, which sense the EMT using specific promoters that respond to transcription factors typical of EMT activation (EMT-TFs). The transcriptional strength of EMT-sensing promoters decreased more than 13-fold in response to the overexpression of the EMT-TF. Then, the NOT gate circuits were built by placing the tetR transcription repressor under the control of EMT sensing promoters and expressed an output signal using the constitutive CMV promoter modified with tetO sites This circuit is named EMT sensing and responding circuits. When the EMT transcription factors was present, we observed a 5.8-fold signal increase in the system. Then, we successfully distinguished mesenchymal breast cancer cells from epithelial cancer cells and repressed the proliferation of EMT tumor cells using our circuits. The EMT sensing and responding circuits are promising tools for the identification of EMT cells, which is crucial for EMT-related disease therapy and investigating the mechanisms underlying the reversible EMT process. [ABSTRACT FROM AUTHOR]

Drought stress impairs crop growth and development. BEL1-like family transcription factors may be involved in plant response to drought stress, but little is known of the molecular mechanism by which these proteins regulate plant response and defense to drought stress. Here we show that the BEL1-like transcription factor GhBLH5-A05 functions in cotton (Gossypium hirsutum) response and defense to drought stress. Expression of GhBLH5-A05 in cotton was induced by drought stress. Overexpression of GhBLH5-A05 in both Arabidopsis and cotton increased drought tolerance, whereas silencing GhBLH5- A05 in cotton resulted in elevated sensitivity to drought stress. GhBLH5-A05 binds to cis elements in the promoters of GhRD20-A09 and GhDREB2C-D05 to activate the expression of these genes. GhBLH5- A05 interacted with the KNOX transcription factor GhKNAT6-A03. Co-expression of GhBLH5-A05 and GhKNAT6-A03 increased the transcription of GhRD20-A09 and GhDREB2C-D05. We conclude that GhBLH5-A05 acts as a regulatory factor with GhKNAT6-A03 functioning in cotton response to drought stress by activating the expression of the drought-responsive genes GhRD20-A09 and GhDREB2C-D05. [ABSTRACT FROM AUTHOR]