Letter | Published:

Identification of Tim4 as a phosphatidylserine receptor

Nature volume 450, pages 435439 (15 November 2007) | Download Citation


In programmed cell death, a large number of cells undergo apoptosis, and are engulfed by macrophages to avoid the release of noxious materials from the dying cells1,2. In definitive erythropoiesis, nuclei are expelled from erythroid precursor cells and are engulfed by macrophages. Phosphatidylserine is exposed on the surface of apoptotic cells3 and on the nuclei expelled from erythroid precursor cells4; it works as an ‘eat me’ signal for phagocytes5,6. Phosphatidylserine is also expressed on the surface of exosomes involved in intercellular signalling7. Here we established a library of hamster monoclonal antibodies against mouse peritoneal macrophages, and found an antibody that strongly inhibited the phosphatidylserine-dependent engulfment of apoptotic cells. The antigen recognized by the antibody was identified by expression cloning as a type I transmembrane protein called Tim4 (T-cell immunoglobulin- and mucin-domain-containing molecule; also known as Timd4)8. Tim4 was expressed in Mac1+ cells in various mouse tissues, including spleen, lymph nodes and fetal liver. Tim4 bound apoptotic cells by recognizing phosphatidylserine via its immunoglobulin domain. The expression of Tim4 in fibroblasts enhanced their ability to engulf apoptotic cells. When the anti-Tim4 monoclonal antibody was administered into mice, the engulfment of apoptotic cells by thymic macrophages was significantly blocked, and the mice developed autoantibodies. Among the other Tim family members, Tim1, but neither Tim2 nor Tim3, specifically bound phosphatidylserine. Tim1- or Tim4-expressing Ba/F3 B cells were bound by exosomes via phosphatidylserine, and exosomes stimulated the interaction between Tim1 and Tim4. These results indicate that Tim4 and Tim1 are phosphatidylserine receptors for the engulfment of apoptotic cells, and may also be involved in intercellular signalling in which exosomes are involved.

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We thank R. Hanayama for advice in the initial stage of this project, and M. Fujii and M. Harayama for secretarial assistance. This work was supported in part by Grants-in-Aid from the Ministry of Education, Science, Sports, and Culture in Japan.

Author information

Author notes

    • Kazutoshi Tada

    Present address: Mitsubishi UFJ Research and Consulting, Corporate Strategy Consulting Department I, 2-5-8 Emabashi, Chou-ku, Osaka 541-8512, Japan


  1. Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan

    • Masanori Miyanishi
    •  & Shigekazu Nagata
  2. Department of Genetics,

    • Masanori Miyanishi
    • , Kazutoshi Tada
    •  & Shigekazu Nagata
  3. Department of Cell Biology and Neuroscience, Osaka University Medical School, Osaka 565-0871, Japan

    • Masato Koike
    •  & Yasuo Uchiyama
  4. Division of Cellular Therapy, The Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan

    • Toshio Kitamura
  5. Solution Oriented Research for Science and Technology, Japan Science and Technology Corporation, Kyoto 606-8501, Japan

    • Shigekazu Nagata


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The authors declare no competing financial interests.

Corresponding author

Correspondence to Shigekazu Nagata.

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