alphaB-Crystallin-coated MAP microtubule resists nocodazole and calcium-induced disassembly

J Cell Sci. 2004 Apr 1;117(Pt 9):1719-26. doi: 10.1242/jcs.01021. Epub 2004 Mar 9.

Abstract

alphaB-Crystallin, one of the small heat-shock proteins, is constitutively expressed in various tissues including the lens of the eye. It has been suggested that alphaB-crystallin provides lens transparency but its function in nonlenticular tissues is unknown. It has been reported that alphaB-crystallin is involved in the stabilization and the regulation of cytoskeleton, such as intermediate filaments and actin. In this study, we investigate the possibility whether alphaB-crystallin interacts with the third cytoskeleton component, microtubules (MTs). First, we precisely observed the cellular localization of alphaB-crystallin and MT networks in L6E9 myoblast cells and found a striking coincidence between them. MTs reconstituted from cell lysate contained alphaB-crystallin. Electron micrographs clearly showed direct interactions of purified alphaB-crystallin with the surface of microtubule-associated proteins (MAPs) attached to MTs. Purified alphaB-crystallin bound to MAP-MTs in a concentration-dependent manner. However, alphaB-crystallin did not bind MTs reconstituted from purified tubulin. Finally, we observed that alphaB-crystallin increased the resistance of MTs to depolymerization in cells and in vitro. Taken together, these results suggest that one of the functions of alphaB-crystallin is to bind MTs via MAP(s) and to give the MTs resistance to disassembly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / pharmacology*
  • Cattle
  • Cell Line
  • Cell Line, Tumor
  • Microscopy, Fluorescence
  • Microtubule-Associated Proteins / metabolism*
  • Microtubule-Associated Proteins / ultrastructure
  • Microtubules / drug effects*
  • Microtubules / metabolism*
  • Microtubules / ultrastructure
  • Nocodazole / pharmacology*
  • Oligonucleotides, Antisense
  • Podophyllotoxin / pharmacology
  • Protein Binding
  • Rats
  • alpha-Crystallin B Chain / genetics
  • alpha-Crystallin B Chain / metabolism*
  • alpha-Crystallin B Chain / ultrastructure

Substances

  • Microtubule-Associated Proteins
  • Oligonucleotides, Antisense
  • alpha-Crystallin B Chain
  • Podophyllotoxin
  • Nocodazole
  • Calcium