FH1FH2mDia2 stabilizes MTs against dilution-induced disassembly and the activity maps to the FH2 domain. (A) Immunostaining of MTs that survived dilution induced depolymerization upon incubation with the following indicated proteins (all proteins were His-tagged except BSA): GSK3β, glycogen synthase kinase 3β; WT, wild-type FH1FH2mDia2; I704A, K853A, and W630A, mutant FH1FH2mDia2; FH1FH2ΔC, FH2ΔN, and FH2C, fragments of FH1FH2mDia2 (see B). (B) Diagram of fragments of FH1FH2mDia2 used for MT stability tests in A. (C) Immunostaining of Glu and Tyr MTs and actin in wounded starved NIH3T3 fibroblasts expressing EGFP-FH1FH2ΔC or EGFP-FH2CmDia2. (D) Quantification of cells expressing the indicated constructs that exhibited stable Glu MTs. Data are mean ± SD from three independent experiments (n > 70 cells). Asterisk indicates P < 0.001, calculated by χ2 test (one degree of freedom). Bars, 10 μm.
