title: Kissing and nanotunneling mediate intermitochondrial communication in the heart.
abstract: Mitochondria in many types of cells are dynamically interconnected through constant fusion and fission, allowing for exchange of mitochondrial contents and repair of damaged mitochondria. However, constrained by the myofibril lattice, the ∼6,000 mitochondria in the adult mammalian cardiomyocyte display little motility, and it is unclear how, if at all, they communicate with each other. By means of target-expressing photoactivatable green fluorescent protein (PAGFP) in the mitochondrial matrix or on the outer mitochondrial membrane, we demonstrated that the local PAGFP signal propagated over the entire population of mitochondria in cardiomyocytes on a time scale of ∼10 h. Two elemental steps of intermitochondrial communications were manifested as either a sudden PAGFP transfer between a pair of adjacent mitochondria (i.e., "kissing") or a dynamic nanotubular tunnel (i.e., "nanotunneling") between nonadjacent mitochondria. The average content transfer index (fractional exchange) was around 0.5; the rate of kissing was 1‰ s(-1) per mitochondrial pair, and that of nanotunneling was about 14 times smaller. Electron microscopy revealed extensive intimate contacts between adjacent mitochondria and elongated nanotubular protrusions, providing a structural basis for the kissing and nanotunneling, respectively. We propose that, through kissing and nanotunneling, the otherwise static mitochondria in a cardiomyocyte form one dynamically continuous network to share content and transfer signals.
authors: State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, and College of Engineering,  Peking University, Beijing 100871,  China.
authors: Xiaohu
authors: X
authors: Huang
authors: Lei
authors: L
authors: Sun
authors: Shuangxi
authors: S
authors: Ji
authors: Ting
authors: T
authors: Zhao
authors: Wanrui
authors: W
authors: Zhang
authors: Jiejia
authors: J
authors: Xu
authors: Jue
authors: J
authors: Zhang
authors: Yanru
authors: Y
authors: Wang
authors: Xianhua
authors: X
authors: Wang
authors: Clara
authors: C
authors: Franzini-Armstrong
authors: Ming
authors: M
authors: Zheng
authors: Heping
authors: H
authors: Cheng
mesh_terms: D000818:Animals; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008929:Mitochondria, Heart / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats
chemical_list: D049452:Green Fluorescent Proteins
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