Research Report - Nikolaus-Fiebiger-Zentrum für Molekulare Medizin

organisation of the microtubule cytoskeleton. Of note, EB1 interacts with APC to
stabilise microtubules. Amer2 binds to EB1 via specific S/TxIP motifs and recruits it to
the plasma membrane. Coexpression of Amer2 and EB1 generates stabilised
microtubules whereas knockdown of Amer2 leads to destabilisation of microtubules.
Knockdown of Amer2, APC, or EB1 reduces cell migration, and morpholino-mediated
downregulation of Xenopus Amer2 blocks convergent extension cell movements
suggesting that the Amer2/EB1/APC complex regulates cell migration by altering
microtubule stability (Pfister et al., JBC in revision). The Amer2 knock-out in mice has
recently been generated in our lab but shows no obvious phenotypes, possibly due to
compensation by Amer2. We are currently generating double-knockout animals of
Amer1 and Amer2 for further characterization.
Fig. 2 Scheme of Amer2 interactions with APC and EB1 in microtubule stabilization.
Amer3
Amer3 does not interact with the plasma membrane and is mainly located in the
cytoplasm and occasionally in the cell nucleus. Moreover, in contrast to Amer1 and
Amer2 this protein acts as an activator rather than inhibitor of Wnt signalling.
Ongoing work aims at identifying the precise function of Amer3 and its interplay with
the other Amers in the Wnt pathway.
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