Membrane nanotube
Encyclopedia
Membrane nanotubes, membrane nanotubules or cytonemes are long and thin tubes formed from the plasma membrane that connect different animal cells over long distances. Two types of nanotubes have been observed. The first type are less than 0.7 micrometre
s in diameter, contain actin
and carry portions of plasma membrane between cells in both directions. The second type are larger (>0.7 μm), contain both actin and microtubule
s and can carry components of the cytoplasm
between cells, such as vesicles
and organelle
s.
These structures may be involved in cell-to-cell communication, transfer of nucleic acids between cells in a tissue, and the spread of pathogens or toxins such as HIV
and prion
s. Membrane nanotubes were first described in a 1999 Cell
article examining the development of Drosophila melanogaster
wing imaginal disc
s. More recently, a Science
article published in 2004 described structures that connected various types of immune cell together, as well as connections between cells in tissue culture
.
Similar structures, called plasmodesmata
, interconnect plant cells and stromule
s interconnect plastids.
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
s in diameter, contain actin
Actin
Actin is a globular, roughly 42-kDa moonlighting protein found in all eukaryotic cells where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans...
and carry portions of plasma membrane between cells in both directions. The second type are larger (>0.7 μm), contain both actin and microtubule
Microtubule
Microtubules are a component of the cytoskeleton. These rope-like polymers of tubulin can grow as long as 25 micrometers and are highly dynamic. The outer diameter of microtubule is about 25 nm. Microtubules are important for maintaining cell structure, providing platforms for intracellular...
s and can carry components of the cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
between cells, such as vesicles
Vesicle (biology)
A vesicle is a bubble of liquid within another liquid, a supramolecular assembly made up of many different molecules. More technically, a vesicle is a small membrane-enclosed sack that can store or transport substances. Vesicles can form naturally because of the properties of lipid membranes , or...
and organelle
Organelle
In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer....
s.
These structures may be involved in cell-to-cell communication, transfer of nucleic acids between cells in a tissue, and the spread of pathogens or toxins such as HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
and prion
Prion
A prion is an infectious agent composed of protein in a misfolded form. This is in contrast to all other known infectious agents which must contain nucleic acids . The word prion, coined in 1982 by Stanley B. Prusiner, is a portmanteau derived from the words protein and infection...
s. Membrane nanotubes were first described in a 1999 Cell
Cell (journal)
Cell is a peer-reviewed scientific journal publishing research papers across a broad range of disciplines within the life sciences. Areas covered include molecular biology, cell biology, systems biology, stem cells, developmental biology, genetics and genomics, proteomics, cancer research,...
article examining the development of Drosophila melanogaster
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...
wing imaginal disc
Imaginal disc
An imaginal disc is one of the parts of a holometabolous insect larva that will become a portion of the outside of the adult insect during the pupal transformation. Contained within the body of the larva, there are pairs of discs that will form, for instance, the wings or legs or antennae or other...
s. More recently, a Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
article published in 2004 described structures that connected various types of immune cell together, as well as connections between cells in tissue culture
Tissue culture
Tissue culture is the growth of tissues or cells separate from the organism. This is typically facilitated via use of a liquid, semi-solid, or solid growth medium, such as broth or agar...
.
Similar structures, called plasmodesmata
Plasmodesmata
Plasmodesmata are microscopic channels which traverse the cell walls of plant cells and some algal cells, enabling transport and communication between them. Species that have plasmodesmata include members of the Charophyceae, Charales and Coleochaetales , as well as all embryophytes, better known...
, interconnect plant cells and stromule
Stromule
Stromules are microscopic structures found in plant cells. Stromules are highly dynamic structures extending from the surface of all plastid types, including proplastids, chloroplasts, etioplasts, leucoplasts, amyloplasts, and chromoplasts...
s interconnect plastids.
External links
- Hans-Hermann Gerdes Research Group - The laboratory that first observed membrane nanotubes