Cell-to-cell communication is a fundamental process in every multicellular organism. In addition to membrane-bound and released factors, the sharing of cytosolic components represents a new, poorly explored signaling route. An extraordinary example of this communication channel is the direct transport of mitochondria between cells. In this review, we discuss how intercellular mitochondrial transfer can be used by cancer cells to sustain their high metabolic requirements and promote drug resistance and describe relevant molecular players in the context of current and future cancer therapy.
- Publication type
- Journal Article MeSH
- Review MeSH
Current dogma holds that genes are the property of individual mammalian cells and partition between daughter cells during cell division. However, and rather unexpectedly, recent research has demonstrated horizontal cell-to-cell transfer of mitochondria and mitochondrial DNA in several mammalian cell culture systems. Furthermore, unequivocal evidence that mitochondrial DNA transfer occurs in vivo has now been published. While these studies show horizontal transfer of mitochondrial DNA in pathological settings, it is also possible that intercellular mitochondrial transfer is a fundamental physiological process with a role in development and tissue homeostasis.
- MeSH
- Cell Division genetics MeSH
- Humans MeSH
- Cell Communication genetics MeSH
- DNA, Mitochondrial genetics MeSH
- Mitochondria genetics MeSH
- Gene Transfer, Horizontal genetics MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
The appearance of alpha-synuclein-positive inclusion bodies (Lewy bodies) and the loss of catecholaminergic neurons are the primary pathological hallmarks of Parkinson's disease (PD). However, the dysfunction of mitochondria has long been recognized as a key component in the progression of the disease. Dysfunctional mitochondria can in turn lead to dysregulation of calcium homeostasis and, especially in dopaminergic neurons, raised mean intracellular calcium concentration. As calcium binding to alpha-synuclein is one of the important triggers of alpha-synuclein aggregation, mitochondrial dysfunction will promote inclusion body formation and disease progression. Increased reactive oxygen species (ROS) resulting from inefficiencies in the electron transport chain also contribute to the formation of alpha-synuclein aggregates and neuronal loss. Recent studies have also highlighted defects in mitochondrial clearance that lead to the accumulation of depolarized mitochondria. Transaxonal and intracytoplasmic translocation of mitochondria along the microtubule cytoskeleton may also be affected in diseased neurons. Furthermore, nanotube-mediated intercellular transfer of mitochondria has recently been reported between different cell types and may have relevance to the spread of PD pathology between adjacent brain regions. In the current review, the contributions of both intracellular and intercellular mitochondrial dynamics to the etiology of PD will be discussed.
- Publication type
- Journal Article MeSH
- Review MeSH
The view that genes are constrained within somatic cells is challenged by in vitro evidence, and more recently by in vivo studies which demonstrate that mitochondria with their mitochondrial DNA (mtDNA) payload not only can, but do move between cells in tumour models and in mouse models of tissue damage. Using mouse tumour cell models without mtDNA to reflect mtDNA damage, we have shown that these cells grow tumours only after acquiring mtDNA from cells in the local microenvironment resulting in respiration recovery, tumorigenesis and metastasis. Mitochondrial transfer between cells has also been demonstrated following ischaemia-induced injury in the heart and brain and in lung epithelium, and following lung inflammation. In vitro investigations suggest that stem cells may be mitochondrial donors. The ability of mitochondria to move between cells appears to be an evolutionarily-conserved phenomenon, relevant to diseases with compromised mitochondrial function including neurodegenerative, neuromuscular and cardiovascular diseases as well as cancer and ageing.
- MeSH
- Organelle Biogenesis MeSH
- Humans MeSH
- DNA, Mitochondrial genetics metabolism MeSH
- Mitochondria genetics metabolism pathology MeSH
- Tumor Microenvironment MeSH
- Neoplasms genetics metabolism pathology MeSH
- Cell Movement * MeSH
- DNA Damage MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Gap junctional intercellular communication (GJIC) is a vital cellular process required for maintenance of tissue homeostasis. In vitro assessment of GJIC represents valuable phenotypic endpoint that could be effectively utilized as an integral component in modern toxicity testing, drug screening or biomedical in vitro research. However, currently available methods for quantifying GJIC with higher-throughputs typically require specialized equipment, proprietary software and/or genetically engineered cell models. To overcome these limitations, we present here an innovative adaptation of traditional, fluorescence microscopy-based scrape loading-dye transfer (SL-DT) assay, which has been optimized to simultaneously evaluate GJIC, cell density and viability. This multiparametric method was demonstrated to be suitable for various multiwell microplate formats, which facilitates an automatized image acquisition. The assay workflow is further assisted by an open source-based software tools for batch image processing, analysis and evaluation of GJIC, cell density and viability. Our results suggest that this approach provides a simple, fast, versatile and cost effective way for in vitro high-throughput assessment of GJIC and other related phenotypic cellular events, which could be included into in vitro screening and assessment of pharmacologically and toxicologically relevant compounds.
- MeSH
- Microscopy, Fluorescence methods MeSH
- Rats MeSH
- Cells, Cultured MeSH
- Gap Junctions * MeSH
- Cell Communication * MeSH
- Molecular Imaging methods MeSH
- Cell Count * MeSH
- Image Processing, Computer-Assisted methods MeSH
- Cell Survival * MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Mitochondria are organelles essential for tumor cell proliferation and metastasis. Although their main cellular function, generation of energy in the form of ATP is dispensable for cancer cells, their capability to drive their adaptation to stress originating from tumor microenvironment makes them a plausible therapeutic target. Recent research has revealed that cancer cells with damaged oxidative phosphorylation import healthy (functional) mitochondria from surrounding stromal cells to drive pyrimidine synthesis and cell proliferation. Furthermore, it has been shown that energetically competent mitochondria are fundamental for tumor cell migration, invasion and metastasis. The spatial positioning and transport of mitochondria involves Miro proteins from a subfamily of small GTPases, localized in outer mitochondrial membrane. Miro proteins are involved in the structure of the MICOS complex, connecting outer and inner-mitochondrial membrane; in mitochondria-ER communication; Ca2+ metabolism; and in the recycling of damaged organelles via mitophagy. The most important role of Miro is regulation of mitochondrial movement and distribution within (and between) cells, acting as an adaptor linking organelles to cytoskeleton-associated motor proteins. In this review, we discuss the function of Miro proteins in various modes of intercellular mitochondrial transfer, emphasizing the structure and dynamics of tunneling nanotubes, the most common transfer modality. We summarize the evidence for and propose possible roles of Miro proteins in nanotube-mediated transfer as well as in cancer cell migration and metastasis, both processes being tightly connected to cytoskeleton-driven mitochondrial movement and positioning.
- Publication type
- Journal Article MeSH
- Review MeSH
The increased interest in assisted reproduction through in vitro fertilization (IVF) leads to an urgent need to identify biomarkers that reliably highly predict the success of pregnancy. Despite advances in diagnostics, treatment, and IVF approaches, the 30% success rate of IVF seems insurmountable. Idiopathic infertility does not have any explanation for IVF failure especially when a patient is treated with a healthy competitive embryo capable of implantation and development. Since appropriate intercellular communication is essential after embryo implantation, the emergence of the investigation of embryonic secretome including short non-coding RNA (sncRNA) molecules is crucial. That's why biomarker identification, sncRNAs secreted during the IVF process into the blastocyst's cultivation medium, by the implementation of artificial intelligence opens the door to a better understanding of the bidirectional communication between embryonic cells and the endometrium and so the success of the IVF. This study presents a set of promising new sncRNAs which are revealed to predictively distinguish a high-quality embryo, suitable for an embryo transfer in the IVF process, from a low-quality embryo with 86% accuracy. The identified exact combination of miRNAs/piRNAs as a non-invasively obtained biomarker for quality embryo determination, increasing the likelihood of implantation and the success of pregnancy after an embryo transfer.
The scrape loading/dye transfer (SL/DT) technique is a simple functional assay for the simultaneous assessment of gap junctional intercellular communication (GJIC) in a large population of cells. The equipment needs are minimal and are typically met in standard cell biology labs, and SL/DT is the simplest and quickest of all the assays that measure GJIC. This assay has also been adapted for in vivo studies. The SL/DT assay is also conducive to a high-throughput setup with automated fluorescence microscopy imaging and analysis to elucidate more samples in shorter time, and hence can serve a broad range of in vitro pharmacological and toxicological needs.
- MeSH
- Dextrans metabolism MeSH
- Fluorescent Dyes metabolism MeSH
- Microscopy, Fluorescence methods MeSH
- Isoquinolines metabolism MeSH
- Cells, Cultured MeSH
- Gap Junctions metabolism ultrastructure MeSH
- Cell Communication * MeSH
- Mice MeSH
- Rhodamines metabolism MeSH
- Sertoli Cells MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
Mitochondria are organelles present in most eukaryotic cells, where they play major and multifaceted roles. The classical notion of the main mitochondrial function as the powerhouse of the cell per se has been complemented by recent discoveries pointing to mitochondria as organelles affecting a number of other auxiliary processes. They go beyond the classical energy provision via acting as a relay point of many catabolic and anabolic processes, to signaling pathways critically affecting cell growth by their implication in de novo pyrimidine synthesis. These additional roles further underscore the importance of mitochondrial homeostasis in various tissues, where its deregulation promotes a number of pathologies. While it has long been known that mitochondria can move within a cell to sites where they are needed, recent research has uncovered that mitochondria can also move between cells. While this intriguing field of research is only emerging, it is clear that mobilization of mitochondria requires a complex apparatus that critically involves mitochondrial proteins of the Miro family, whose role goes beyond the mitochondrial transfer, as will be covered in this review.
- MeSH
- Biological Transport, Active physiology MeSH
- Humans MeSH
- Mitochondrial Proteins genetics metabolism MeSH
- Mitochondria genetics metabolism MeSH
- Pyrimidines biosynthesis MeSH
- rho GTP-Binding Proteins genetics metabolism MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Video-Audio Media MeSH
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
