Authors
Ludington, William B.Wemmer, Kimberly A.
Lechtreck, Karl-Ferdinand
Witman, George B.
Marshall, Wallace F.
UMass Chan Affiliations
Department of Cell and Developmental BiologyDocument Type
Journal ArticlePublication Date
2013-03-05Keywords
CiliaFlagella
Carrier Proteins
Molecular Motor Proteins
Cell and Developmental Biology
Cell Biology
Metadata
Show full item recordAbstract
Cilia and flagella are microtubule-based organelles that protrude from the cell body. Ciliary assembly requires intraflagellar transport (IFT), a motile system that delivers cargo from the cell body to the flagellar tip for assembly. The process controlling injections of IFT proteins into the flagellar compartment is, therefore, crucial to ciliogenesis. Extensive biochemical and genetic analyses have determined the molecular machinery of IFT, but these studies do not explain what regulates IFT injection rate. Here, we provide evidence that IFT injections result from avalanche-like releases of accumulated IFT material at the flagellar base and that the key regulated feature of length control is the recruitment of IFT material to the flagellar base. We used total internal reflection fluorescence microscopy of IFT proteins in live cells to quantify the size and frequency of injections over time. The injection dynamics reveal a power-law tailed distribution of injection event sizes and a negative correlation between injection size and frequency, as well as rich behaviors such as quasiperiodicity, bursting, and long-memory effects tied to the size of the localized load of IFT material awaiting injection at the flagellar base, collectively indicating that IFT injection dynamics result from avalanche-like behavior. Computational models based on avalanching recapitulate observed IFT dynamics, and we further show that the flagellar Ras-related nuclear protein (Ran) guanosine 5'-triphosphate (GTP) gradient can in theory act as a flagellar length sensor to regulate this localized accumulation of IFT. These results demonstrate that a self-organizing, physical mechanism can control a biochemically complex intracellular transport pathway.Source
Proc Natl Acad Sci U S A. 2013 Mar 5;110(10):3925-30. doi: 10.1073/pnas.1217354110 Link to article on publisher's site
DOI
10.1073/pnas.1217354110Permanent Link to this Item
http://hdl.handle.net/20.500.14038/26442PubMed ID
23431147Related Resources
Rights
Freely available online through the PNAS open access option. Publisher PDF posted as allowed by the publisher's author rights policy at http://www.pnas.org/site/aboutpnas/authorfaq.xhtml.
ae974a485f413a2113503eed53cd6c53
10.1073/pnas.1217354110