Susumu Tonegawa (利根川 進,Tonegawa Susumu; born September 5, 1939) is a Japanese scientist who was the sole recipient of theNobel Prize for Physiology or Medicine in 1987 for his discovery ofV(D)J recombination, thegenetic mechanism which producesantibody diversity.[1] Although he won the Nobel Prize for his work inimmunology, Tonegawa is amolecular biologist by training and he again changed fields following his Nobel Prize win; he now studiesneuroscience, examining the molecular, cellular and neuronal basis of memory formation and retrieval.
Tonegawa was born inNagoya, Japan and attendedHibiya High School in Tokyo.[2] While a student atKyoto University, Tonegawa became fascinated withoperon theory after reading papers byFrançois Jacob andJacques Monod, whom he credits in part for inspiring his interest in molecular biology.[2] Tonegawa graduated from Kyoto University in 1963 and, due to limited options for molecular biology study in Japan at the time, moved to theUniversity of California, San Diego to do his doctorate study under Dr. Masaki Hayashi. He received his Ph.D. in 1968.
Tonegawa conducted post-doctoral work at theSalk Institute inSan Diego in the laboratory ofRenato Dulbecco. With encouragement from Dr. Dulbecco, Tonegawa moved to theBasel Institute for Immunology in Basel, Switzerland in 1971, where he transitioned from molecular biology into immunology studies and carried out his landmark immunology studies.
In 1981, Tonegawa became a professor at the Massachusetts Institute of Technology. In 1994, he was appointed as the first Director of the MIT Center for Learning and Memory, which developed under his guidance into ThePicower Institute for Learning and Memory. Tonegawa resigned his directorship in 2006 and currently serves as a Picower Professor of Neuroscience and Biology and aHoward Hughes Medical Institute Investigator.
Tonegawa's Nobel Prize work elucidated the genetic mechanism of the adaptiveimmune system, which had been the central question of immunology for over 100 years. Prior to Tonegawa's discovery, one early idea to explain the adaptive immune system suggested that each gene produces one protein; however, there are under 19,000 genes in the human body which nonetheless can produce millions of antibodies. In experiments beginning in 1976, Tonegawa showed that genetic material rearranges itself to form millions of antibodies. Comparing theDNA ofB cells (a type ofwhite blood cell) in embryonic and adultmice, he observed that genes in the mature B cells of the adult mice are moved around, recombined, and deleted to form the diversity of the variable region of antibodies.[3] This process is known asV(D)J recombination.
In 1983, Tonegawa also discovered a transcriptional enhancer element associated with antibody gene complex, the first cellular enhancer element.
Shortly following his Nobel Prize, Tonegawa again changed fields from immunology to neuroscience, where he has focused his research in the ensuing years.
Tonegawa's lab pioneered introductory transgenic and gene-knockout technologies in mammalian systems. He was involved in early work demonstrating the importance of CaMKII- (1992) and the NMDA receptor-dependent synaptic plasticity (1996) in memory formation.
Tonegawa's lab discovered that dendritic neuronal spines in the temporal cortex are a likely target for treatment of Fragile X Syndrome. With one dosage of the inhibitor drug FRAX586, Tonegawa showed a marked reduction of FXS symptoms in the mouse model.[4]
Tonegawa was an early adopter ofoptogenetics andbiotechnology in neuroscience research, leading to his groundbreaking work identifying and manipulatingmemory engram cells. In 2012, his lab demonstrated that the activation of a specific sub-population of mouse hippocampal neurons, labelled during a fear conditioning paradigm, is sufficient to evoke a behavioral response correlated with a precise memory trace. This demonstrated for the first time that memory information is stored in specific cellular ensembles in thehippocampus, now frequently called memory engram cells.[5]
More recently, his lab continues to employ optogenetic technology and virus injection techniques to expand their findings on the engram cell ensemble. Notably, Tonegawa has uncovered the role of memory engram cell ensembles in memory valence,[6] social memory, as well as their role in brain disorders such as depression,[7] amnesia,[8] and Alzheimer's disease. These works provide proofs of concept for future medical treatments in humans through the manipulation of memory engram ensembles.
Tonegawa currently resides in the Boston area with his wife, Mayumi Yoshinari Tonegawa, who worked as anNHK (Japan Broadcasting Corporation) director/interviewer and is now a freelance science writer. The Tonegawas have three children, Hidde Tonegawa, Hanna Tonegawa, and Satto Tonegawa (deceased).
Tonegawa is a fan of the Boston Red Sox, and threw out an opening pitch during their 2004 World Series championship season.
Gillies, S. D., Morrison, S. L., Oi, V. T., & Tonegawa, S. (1983). A tissue-specific transcription enhancer element is located in the major intron of a rearranged immunoglobulin heavy chain gene.Cell, 33(3), 717-728.
Mombaerts, P., Iacomini, J., Johnson, R. S., Herrup, K., Tonegawa, S., & Papaioannou, V. E. (1992). RAG-1-deficient mice have no mature B and T lymphocytes.Cell, 68(5), 869-877.
Silva, A. J., Stevens, C. F., Tonegawa, S., & Wang, Y. (1992). Deficient hippocampal long-term potentiation in alpha-calcium-calmodulin kinase II mutant mice.Science, 257(5067), 201-206.
Shen, J., Bronson, R. T., Chen, D. F., Xia, W., Selkoe, D. J., & Tonegawa, S. (1997). Skeletal and CNS defects in Presenilin-1-deficient mice.Cell, 89(4), 629-639.
Nakazawa, K., Quirk, M. C., Chitwood, R. A., Watanabe, M., Yeckel, M. F., Sun, L. D., Kato, A., Carr, C.A., Johnston, D., Wilson, M.A., & Tonegawa, S. (2002). Requirement for hippocampal CA3 NMDA receptors in associative memory recall.Science, 297(5579), 211-218.
Liu, X., Ramirez, S., Pang, P. T., Puryear, C. B., Govindarajan, A., Deisseroth, K., & Tonegawa, S. (2012). Optogenetic stimulation of a hippocampal engram activates fear memory recall.Nature, 484(7394), 381-385.
Ramirez, S., Liu, X., Lin, P. A., Suh, J., Pignatelli, M., Redondo, R. L., Ryan, T.J., & Tonegawa, S. (2013). Creating a false memory in the hippocampus.Science, 341(6144), 387-391.
