Development of in vivo biosensors using genetic engineering

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1. Monitoring of inflammation Using an inflammation-responsive regulatory element as a molecular sensor, we established a cell-based biosensor for continuous, non-invasive monitoring of local microscopic inflammation in vivo. Glomerulonephritis was used as a model of local inflammation. Mesangial cells were stably transfected with a marker gene encoding secreted alkaline phosphatase (SEAP) under the control of the KB enhancer elements. The established sensor cells were transferred selectively into rat glomeruli via the renal circulation. After induction of acute glomerulonephritis (anti-Thy 1.1 nephritis), the serum level of SEAP was increased transiently in cell-transferred nephritic rats. The kinetics of serum SEAP was closely correlated with the natural course of the inflammation. These results suggested that, without invasive procedures like tissue biopsies, continuous, real-time monitoring of microscopic inflammation is feasible in vivo via locally created, cell-based biosensors.2 … More . Monitoring of endoplasmic reticulum (ER) stress We found that activity of ER stress-responsive alkaline phosphatase (ES-TRAP) produced by transfected cells is rapidly downregulated by ER stress independent of transcriptional regulation. This phenomenon was observed in a wide range of cell types triggered by various ER stress inducers, and the magnitude of the decrease in ES-TRAP was proportional to the extent of ER stress. In transgenic mice constitutively producing ES-TRAP, systemic induction of ER stress by thapsigargin led to reduction in serum ES-TRAP activity. In these mice, administration with lipopolysaccharide and cadmium also caused rapid, transient decrease in serum ES-TRAP activity, and it was correlated with up-regulation of endogenous ER stress markers in several organs. These results elucidated for the first time a possible involvement of ER stress in endotoxemia and toxicity of heavy metal and provided evidence for usefulness of ES-TRAP for continuous, real-time monitoring of ER stress in vivo. Less