Novel FRET-based biosensors for monitoring Presenilin/gamma-secretase activity in live cells

Presenilin (PS)/γ‐secretase is responsible for the proteolytic processing of wide variety of membrane associated proteins that include APP and Notch. Therefore, a change in PS/γ‐secretase activity is linked to essential biological events as well as to the progression of many diseases. However, not much is known about how PS/γ‐secretase activity is spatiotemporally regulated in live cells, mainly because shortcomings of the existing assays prevent monitoring dynamic changes in the activity of PS/γ‐secretase in its normal physiological environment. Here we present successful development and validation of the Förster resonance energy transfer (FRET)‐based biosensors, so called the APP C99 Y‐T and the Notch1 N100 Y‐T biosensors, that enable quantitative monitoring of endogenous PS/γ‐secretase activity in live cells longitudinally on a cell‐by‐cell basis. Using these novel FRET biosensors, we uncovered dynamic spatiotemporal pattern of PS/γ‐secretase activity that is heterogeneously regulated among live neurons. Support or Funding Information NIH: AG 44486 (OB), AG 15379 (OB) and BrightFocus Foundation: A2019056F (MM)