History-dependent catastrophes regulate axonal microtubule behavior.
In Chinese hamster ovary cells, microtubules originate at the microtubule organizing center (MTOC) and grow persistently toward the cell edge, where they undergo catastrophe. In axons, microtubule dynamics must be regulated differently because microtubules grow parallel to the plasma membrane and there is no MTOC. GFP-tagged microtubule plus end tracking proteins (+TIPs) mark the ends of growing neuronal microtubules. Their fluorescent "comet-like" pattern reflects turnover of +TIP binding sites. Using GFP-tagged +TIPs and fluorescence-based segmentation and tracking tools, we show that axonal microtubules grow with a constant average velocity and that they undergo catastrophes at random positions, yet in a programmed fashion. Using protein depletion approaches, we find that the +TIPs CLIP-115 and CLIP-170 affect average microtubule growth rate and growth distance in neurons but not the duration of a microtubule growth event. In N1E-115 neuroblastoma cells, we find that EB1, the core +TIP, regulates microtubule growth rate, growth distance, and duration, consistent with in vitro data. Combined, our data suggest that CLIPs influence the axonal microtubule/tubulin ratio, whereas EB1 stimulates microtubule growth and structural transitions at microtubule ends, thereby regulating microtubule catastrophes and the turnover of +TIP binding sites.
Stepanova
Tatiana
T
Department of Cell Biology and Genetics, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
Smal
Ihor
I
van Haren
Jeffrey
J
Akinci
Umut
U
Liu
Zhe
Z
Miedema
Marja
M
Limpens
Ronald
R
van Ham
Marco
M
van der Reijden
Michael
M
Poot
Raymond
R
Grosveld
Frank
F
Mommaas
Mieke
M
Meijering
Erik
E
Galjart
Niels
N
D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure*; D001665:Binding Sites; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D055785:Gene Knockdown Techniques; D049452:Green Fluorescent Proteins / Q000378:metabolism; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D009474:Neurons / Q000166:cytology; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D008869:Microtubule-Associated Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins