New Light-Controlled Tool ASAP Lets Scientists Switch Cellular Recycling On and Off to Map Its Targets

For decades, scientists who wanted to know what a cell's recycling system actually removes have lacked a good way to ask. On November 12, 2026, a team at the Salk Institute published a study in Nature Cell Biology describing a tool built to answer that question: ASAP, short for Autophagic SNARE for Abrupt Photomanipulation. It uses light to turn autophagy off and on again, quickly, precisely and reversibly.

Autophagy is the process by which cells break down worn-out parts into building blocks that can be reused. Christina Towers, an assistant professor at Salk who holds the Richard Heyman and Anne Daigle Endowed Developmental Chair, leads the lab behind the work. She notes that the word means, roughly, self-eating, and that the process is conserved from plants to humans. Faulty autophagy has been tied to many diseases, and she argues that targeting it will require first understanding its basic biology. The difficulty has been that autophagy responds fast to changes inside a cell, clearing damaged parts while sparing healthy ones. According to Towers, there has been very little consensus on what it targets, largely because the tools were not good enough.

ASAP is an optogenetic tool, meaning cells are engineered so light can control them. The technique transformed neuroscience and was just awarded the 2026 Nobel Prize in Physiology or Medicine. The Salk team took it beyond nerve cells. They designed a protein that, after a small dose of light, relocates inside a cell and blocks autophagy. Because the switch is light, the block can be tuned, applied rapidly and reversed.

The researchers then used ASAP on human cells in petri dishes. The logic was straightforward: when autophagy is blocked, the proteins and cell parts that pile up first are the ones it regulates most tightly and quickly. Working with David Gonzalez at UC San Diego, the team screened the cells' protein content from five minutes after the block up to 60 minutes.

Many of the proteins that accumulated were already known autophagy targets, which first author Payel Mondal, a former postdoctoral researcher in Towers' lab, said confirmed that ASAP was working. But there were surprises, including proteins never before linked to autophagy.

The first involved nuclear pore complexes, the gatekeepers that control what moves in and out of the nucleus, where the instructions for a cell's development and function are transcribed. Together with the lab of Maximiliano D'Angelo at the neighboring Sanford Burnham Prebys Medical Discovery Institute, the team used ASAP to work out how autophagy handles these structures. They identified the exact signal on the pores that autophagy recognizes, and found that it targets only partially built nuclear pore complexes, leaving healthy ones alone.

The second surprise was protein condensates, which act as hubs for regulating protein translation. Within minutes of blocking autophagy, certain types of condensates built up. The researchers traced that buildup to nuclear pore complex proteins accumulating without autophagy to clear them. The result is the first study to link protein translation, the making of proteins, with autophagy, their breakdown. Others have tried, but Towers' lab is the first to point to the connection more specifically.

Next, Towers' group wants to apply ASAP to cancer cells. Her lab has previously shown that cancer cells can rewire their metabolism when autophagy is blocked, and ASAP could reveal how fast that happens. Researchers elsewhere are already seeking collaborations, with particular interest in neurons. Future work may uncover disease-relevant targets in neurodegeneration, cancer, aging and infection.

Other authors came from Salk, UC San Diego and Sanford Burnham Prebys. Funding came from the National Institutes of Health, Pew Charitable Trust, the Chan Zuckerberg Initiative, Howard Hughes Medical Institute, the Waitt Foundation and several Salk funds, among others.