title: Dynein light chain 1 (LC8) association enhances microtubule stability and promotes microtubule bundling.
abstract: BACKGROUND
  Dynein Light Chain 1 (LC8) has been shown to pull down tubulin subunits, suggesting that it interacts with microtubules.
  
  
  RESULTS
  LC8 decorates microtubules in vitro and in Drosophila embryos, promotes microtubule assembly, and stabilizes microtubules both in vitro and in tissue-cultured cells.
  
  
  CONCLUSIONS
  LC8 stabilizes microtubules.
  
  
  CONCLUSIONS
  Data provide the first evidence of a novel MAP-like function of LC8. Dynein light chain 1 (LC8), a highly conserved protein, is known to bind to a variety of different polypeptides. It functions as a dimer, which is inactivated through phosphorylation at the Ser-88 residue. A loss of LC8 function causes apoptosis in Drosophila embryos, and its overexpression induces malignant transformation of breast cancer cells. Here we show that LC8 binds to tubulin, promotes microtubule assembly, and induces the bundling of reconstituted microtubules in vitro. Furthermore, LC8 decorates microtubules both in Drosophila embryos and in HeLa cells, increases the microtubule stability, and promotes microtubule bundling in these cells. Microtubule stability influences a number of different cellular functions including mitosis and cell differentiation. The LC8 overexpression reduces the susceptibility of microtubules to cold and nocodazole-induced depolymerization in tissue-cultured cells and increases microtubule acetylation, suggesting that LC8 stabilizes microtubules. We also show that LC8 knockdown or transfection with inhibitory peptides destabilizes microtubules and inhibits bipolar spindle assembly in HeLa cells. In addition, LC8 knockdown leads to the mitotic block in HeLa cells. Furthermore, molecular docking analysis using the crystal structures of tubulin and LC8 dimer indicated that the latter may bind at α-β tubulin junction in a protofilament at sites distinct from the kinesin and dynein binding sites. Together, we provide the first evidence of a novel microtubule-associated protein-like function of LC8 that could explain its reported roles in cellular metastasis and differentiation.
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India.
authors.forename: Jayant
authors.initials: J
authors.lastname: Asthana
authors.forename: Anuradha
authors.initials: A
authors.lastname: Kuchibhatla
authors.forename: Swadhin Chandra
authors.initials: SC
authors.lastname: Jana
authors.forename: Krishanu
authors.initials: K
authors.lastname: Ray
authors.forename: Dulal
authors.initials: D
authors.lastname: Panda
mesh_terms: D000818:Animals; D004330:Drosophila / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004398:Dyneins / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008870:Microtubules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D029721:Drosophila Proteins; C542608:ctp protein, Drosophila; D004398:Dyneins