Split-Luciferase Reassembly Assay to Measure Endoplasmic Reticulum-Mitochondria Contacts in Live Cells

In my lab, we study interorganal communication that takes a form of membrane contact and their roles in maintaining cellular health, as well as in disease pathogenesis. We're particularly interested in membrane contacts between mitochondria and endoplasmic reticulum and trying to understand how they're regulated and how their dysregulation can lead to neurodegeneration. Although we know that ER mitochondria contacts are important for cell health and their dysregulation is associated with many diseases, we do not know much about how their level is regulated.

The first step to address this is to establish a simple, reliable protocol to measure the level of ER mitochondria contacts in cells. Our split luciferase assay offers an easier and faster way to quantify ER mitochondria contacts in live cells compared to most assays. We take advantage of two split halves of renilla luciferase, one half targeted to ER and the other to mitochondria.

They can be reassembled together only where the ER and mitochondria membranes have close contact, which results in reconstituted luciferase with a full enzyme activity. This method is simple, suitable for high throughput screenings, and easily accessible for many labs. We hope that it will advance the neurodegenerative disease field by identifying molecular and genetic modulators of ER mitochondria contacts that can be further developed into therapeutic agents.

Our results have paved the way for important questions such as how do different drugs or drug combinations affect ER mitochondria contacts, and what are the important molecular players behind these contacts. From these questions, we can gain a better understanding of the mechanism of ER mitochondria contacts, and find ways to combat related diseases.