Filopod


Filopodia (also microspikes) are slender cytoplasmic projections that extend beyond the leading edge of lamellipodia in migrating cells.[1] They contain actin filaments cross-linked into bundles by actin-binding proteins, e.g. fascin and fimbrin.[2] Filopodia form focal adhesions with the substratum, linking it to the cell surface.[3] Many types of migrating cells display filopodia, which are thought to be involved in both sensation of chemotropic cues, and resulting changes in directed locomotion.

Activation of the Rho family of small Ras-related GTPases, particularly cdc42 and their downstream intermediates results in the polymerization of actin fibers by Ena/Vasp homology proteins.[4] Growth factors bind to receptor tyrosine kinases resulting in the polymerization of actin filaments, which, when cross-linked, make up the supporting cytoskeletal elements of filopodia. Rho activity also results in the activation of the phosphorylation of the ezrin-moesin-radixin group promoting the binding of actin filaments to the filopodia membrane.[4]

Filopodia have roles in sensing, migration and cell-cell interactions.[1] To close a wound in vertebrates, growth factors stimulate the formation of filopodia in fibroblasts to direct fibroblast migration and wound closure.[5] In developing neurons, filopodia extend from the growth cone at the leading edge. In neurons deprived of filopodia by partial inhibition of actin filaments polymerization, growth cone extension continues as normal but direction of growth is disrupted and highly irregular.[5] Filopodia-like projections have also been linked to dendrite creation when new synapses are formed in the brain. [6] [7] In macrophages, filopodia act as phagocytic tentacles and pull bound objects towards the cell for phagocytosis.[8]

Filopodia are also used for movement of bacteria between cells, so as to evade the host immune system. The intracellular bacteria Ehrlichia are transported between cells through the host cell filopodia induced by the pathogen during initial stages of infection.[9] Viruses were shown to be transported along filopodia toward the cell body, leading to cell infection.[10] Directed transport of receptor-bound epidermal growth factor (EGF) along filopodia has also been described, supporting the proposed sensing function of filopodia.[11]

References

External links

  • MBInfo - Filopodia
  • [1]de:Filopodium
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.