Takeshi Kusuda
Rheumatologist and researcher at the University of Tokyo who studies how B cells go wrong in lupus, and first author of the 2026 study tying the arginine sensor CASTOR1 to mTORC1 in antibody-making cells
Department of Allergy and Rheumatology, Graduate School of Medicine, The University of Tokyo (group of senior author Fujio, 2026) · Department of Medicine and Rheumatology, Tokyo Metropolitan Geriatric Hospital (2023) · Department of Rheumatology, Tokyo Medical and Dental University (2016)
Cells check whether they have enough of each amino acid before they grow. CASTOR1 is a sensor for the amino acid arginine: when arginine is low, CASTOR1 holds mTORC1, the growth-control complex, in check. In the Atlas study KUS2026, Kusuda and colleagues in the University of Tokyo group of senior author Fujio gave CASTOR1 a clear job in the body. In mice without CASTOR1, mTORC1 was overactive in B cells, the immune cells that make antibodies. The mice made more plasma cells (antibody factories), more antibodies including ones against their own DNA, and developed kidney inflammation like that seen in lupus.
Systemic lupus erythematosus is an autoimmune disease in which the immune system attacks the body's own tissues. In blood from people with lupus, plasmablasts with less CASTOR1 went with more active disease. That human result is a correlation; the cause-and-effect evidence comes from mice. The study is one of few that link a specific nutrient sensor upstream of mTORC1 to a human autoimmune disease.
PubMed shows Kusuda as a clinician as well as a researcher: a 2016 case report from the Department of Rheumatology at Tokyo Medical and Dental University, and a 2023 letter on COVID-19 vaccination and rheumatoid arthritis in older patients from the Tokyo Metropolitan Geriatric Hospital, with a joint affiliation at the University of Tokyo. Rank and training details could not be confirmed.
Milestones in the Atlas
A selection, not a full bibliography: only papers that meet the Atlas inclusion criteria.
| Year | Evidence | Study |
|---|---|---|
| 2026 | M | CASTOR1 regulates humoral immune responses and contributes to the pathogenesis of systemic lupus erythematosus KUS2026 First author: showed in mice that losing the arginine sensor CASTOR1 overactivates mTORC1 in B cells and leads to lupus-like autoantibodies and kidney disease, with a matching correlation in patients. |
Co-authors in the Atlas 1
People with a profile here who share at least one study with Takeshi Kusuda.
ShowHide
- Keishi Fujio Rheumatologist and immunologist who studies how self-tolerance breaks down in autoimmune disease, including lupus, and how nutrient sensing by CASTOR1 shapes B-cell responses.
Every researcher with a profile →
Thank you. That helps us know which pages have been read by someone who knows the work.
Thank you. We will check it and correct the page.
Thank you. Your answer was counted anonymously.