Exosomes versus microexosomes: Shared components but distinct functions.
In multicellular organisms, cellular components are constantly translocated within cells and are also transported exclusively between limited cells, regardless of their physical distance. Exosomes function as one of the key mediators of intercellular transportation. External vesicles were identified 50 years ago in plants and now reconsidered to be exosome-like vesicles. Meanwhile, a well-known exosomal component, tetraspanin CD9, regulates sperm-egg fusion in mammals. A number of Arabidopsis tetraspanins are also expressed in reproductive tissues at fertilization, and are localized at the plasma membrane of protoplasts. Moreover, CD9-containing structures (or 'microexosomes') are released from mouse eggs during their maturation and promote the sperm-egg fusion. This phenomenon implies that two types of shared-component intercellular carriers might be released from multiple types of plant and animal cells, which widely regulate biological phenomena. We herein highlight their discrete structures, formation processes, and functions.
Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan. miyado-k@ncchd.go.jp.
Kenji
K
Miyado
Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.|Department of Perinatal Medicine and Maternal Care, National Center for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
Woojin
W
Kang
Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan.
Kenji
K
Yamatoya
Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa, 214-8571, Japan.
Maito
M
Hanai
Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.|Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa, 214-8571, Japan.
Akihiro
A
Nakamura
Department of Tropical Medicine and Parasitology, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Toshiyuki
T
Mori
Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
Mami
M
Miyado
Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan. nkawano@meiji.ac.jp.|Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa, 214-8571, Japan. nkawano@meiji.ac.jp.
Natsuko
N
Kawano
D000818:Animals; D017360:Arabidopsis / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology; D055354:Exosomes / Q000378:metabolism* / Q000502:physiology*; D005306:Fertilization / Q000502:physiology*; D008297:Male; D008561:Membrane Fusion / Q000502:physiology; D051379:Mice; D009865:Oocytes / Q000502:physiology; D018521:Plant Physiological Phenomena; D010944:Plants; D022142:Secretory Vesicles; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology; D060245:Tetraspanin 29 / Q000378:metabolism; D059470:Tetraspanins / Q000378:metabolism* / Q000502:physiology*
D060245:Tetraspanin 29; D059470:Tetraspanins
CD9; Exosome; Intercellular transportation; Membrane fusion; Microexosome; Tetraspanin