Xin Gu
Cell biologist who discovered SAMTOR, the sensor that lets mTORC1 read the methyl donor SAM, as a PhD student at MIT, and who now leads a lab at Dana-Farber and Harvard Medical School studying ubiquitin-independent protein destruction by the midnolin-proteasome pathway
Assistant Professor of Cancer Biology, Dana-Farber Cancer Institute, and of Cell Biology, Harvard Medical School (since 2024) · postdoc, Michael Greenberg lab, Department of Neurobiology, Harvard Medical School (2021–2024) · PhD in Biology, MIT (David Sabatini lab, Whitehead Institute) · BS in Biology, Peking University
Portrait: Dana-Farber Cancer Institute (Xin Gu Lab)
mTORC1, the growth-control complex, only switches on when a cell has enough nutrients. By 2017 the Sabatini lab had found sensors for the amino acids leucine and arginine. Xin Gu, first author of the 2017 Science paper on SAMTOR (GU2017), found that mTORC1 also reads a metabolite. SAMTOR binds S-adenosylmethionine (SAM), the molecule cells use to hand out methyl groups, which is made from the amino acid methionine. When methionine runs low, SAM falls, SAMTOR is freed to bind GATOR1, a complex that turns mTORC1 off, and mTORC1 signalling drops. The work was done in human cells. This is relevant to why restricting methionine in the diet affects ageing.
Gu is also a co-author on three other Atlas papers from the same lab: KICSTOR, a complex that holds GATOR1 on the lysosome so nutrients can control mTORC1 (WOL2017); the cryo-EM structure that shows how raptor docks on the Rag-Ragulator complex at the lysosome (ROG2019); and the cryo-EM structure of GATOR2, a large cage-shaped complex that sits upstream of mTORC1 (VAL2022).
According to the lab's official page, Gu studied biology at Peking University and earned a PhD in Biology at MIT, then did postdoctoral work in the Department of Neurobiology at Harvard Medical School; the Greenberg lab lists Gu as a postdoctoral fellow from 2021 to 2024. There Gu was first author of a 2023 Science paper showing that a protein called midnolin delivers many nuclear proteins, including transcription factors made from immediate-early genes, to the proteasome for destruction without the usual ubiquitin tag. Since 2024 Gu has been Assistant Professor of Cancer Biology at Dana-Farber and of Cell Biology at Harvard Medical School. The lab studies how cells keep their protein content stable, starting with the midnolin-proteasome pathway; a 2025 Molecular Cell paper from the lab solved structures of the midnolin-proteasome complex and linked low midnolin to the survival of myeloma cells.
Milestones in the Atlas
A selection, not a full bibliography: only papers that meet the Atlas inclusion criteria.
| Year | Evidence | Study |
|---|---|---|
| 2017 | M | KICSTOR recruits GATOR1 to the lysosome and is necessary for nutrients to regulate mTORC1 WOL2017 Co-author on the discovery of KICSTOR, which tethers GATOR1 to the lysosome and is needed for nutrient control of mTORC1. |
| 2017 | M | SAMTOR is an S-adenosylmethionine sensor for the mTORC1 pathway GU2017 First author: identified SAMTOR as the SAM sensor that links methionine supply to mTORC1 through GATOR1. |
| 2019 | M | Structural basis for the docking of mTORC1 on the lysosomal surface ROG2019 Co-author on the cryo-EM structure showing how raptor reads the nucleotide state of the Rag GTPases before mTORC1 docks on the lysosome. |
| 2022 | M | Structure of the nutrient-sensing hub GATOR2 VAL2022 Co-author on the cryo-EM structure of the nutrient-sensing hub GATOR2. |
Co-authors in the Atlas 18
People with a profile here who share at least one study with Xin Gu.
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- David M. Sabatini 4 shared studies Identified mTOR (as RAFT1) in 1994. His lab then mapped much of the machinery around it: raptor and rictor at the core of mTORC1 and mTORC2, the Rag–Ragulator system that docks mTORC1 on the lysosome, and the sensors that detect leucine, arginine and SAM
- Edward J. Brignole 2 shared studies Research scientist who directs the cryo-electron microscopy facility at MIT.nano and whose cryo-EM work helped solve the structures of GATOR1, GATOR2 and Raptor docked on the Rag GTPases for the Sabatini lab
- Jose M. Orozco 2 shared studies Researcher trained in David Sabatini's laboratory at the Whitehead Institute and MIT who showed that mTORC1 senses glucose through the glycolysis metabolite DHAP
- Kacper B. Rogala 2 shared studies Solved the near-atomic cryo-EM structure that shows how mTORC1 physically docks at the lysosome by reading the Rag GTPases
- Kendall J. Condon 2 shared studies Ran genome-wide CRISPR screens revealing how mitochondrial stress signals to mTORC1
- Lynne Chantranupong 2 shared studies Showed as a Sabatini-lab graduate student that the Sestrins act through GATOR2 to regulate amino-acid signalling to mTORC1. She then discovered the CASTOR proteins, the cell's arginine sensors for the pathway
- Monther Abu-Remaileh 2 shared studies Worked out how to isolate lysosomes fast enough to measure what is inside them, and found that mTOR controls what gets out
- Robert A. Saxton 2 shared studies Solved, as a Sabatini-lab graduate student, the structures of the leucine sensor Sestrin2 and the arginine sensor CASTOR1, showing how each one grips its amino acid. He also co-wrote a widely cited 2017 review of mTOR signalling with David Sabatini
- Sonia M. Scaria 2 shared studies Contributed, as an MIT undergraduate in the Sabatini lab, to the discovery of CASTOR1 as the arginine sensor and SAMTOR as the SAM sensor of the mTORC1 pathway
- Grace Y. Liu Wrote with David Sabatini a major 2020 review of mTOR in nutrition, growth and ageing, and in the Sabatini lab studied how mTORC1 senses nutrients such as serine
- Gregory A. Wyant Showed that the lysosomal protein SLC38A9 exports leucine and other essential amino acids out of the lysosome, letting cells grow on proteins they have taken up and broken down there
- J. Wade Harper Co-discovered the F-box motif that links substrates to SCF ubiquitin ligases, and co-leads with Steven Gygi the BioPlex protein-interaction map, which contributed to the discoveries of the CASTOR and SAMTOR nutrient sensors
- Kuang Shen Solved, as a Sabatini-lab postdoc, cryo-EM structures of GATOR1 and of the FLCN–FNIP2–Rag–Ragulator complex, two switches that set mTORC1 activity. His UMass Chan lab studies the structural basis of nutrient sensing
- Max L. Valenstein First author of the cryo-EM structures of GATOR2, the hub that tells mTORC1 whether amino acids are present, alone and bound to the sensors Sestrin2 and CASTOR1
- Nouf N. Laqtom Cell biologist who helped develop methods to purify intact lysosomes and used them to find what the Batten disease gene CLN3 does, and who now runs a lab at KAUST on lysosome and endoplasmic reticulum defects in rare brain and metabolic diseases
- Pranav V. Lalgudi Co-author of the cryo-EM structures of GATOR2, the nutrient-sensing hub of mTORC1, in 2022 and of GATOR2 bound to Sestrin2 and CASTOR1 in 2025
- Rachel L. Wolfson Identified Sestrin2 as the direct leucine sensor of the mTORC1 pathway as a Sabatini-lab MD-PhD student. She also co-discovered KICSTOR, the complex that recruits GATOR1 to the lysosome
- Steven P. Gygi Mass-spectrometry scientist whose Harvard lab builds large-scale proteomics methods, including the BioPlex human protein-interaction map, and contributed proteomics to the discoveries of the CASTOR and SAMTOR nutrient sensors
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